bluuebunny/crossref_metadata_2025 huggingface dataset:
Langmuir probe, optical, and mass characterization of a DC CO2–H2 plasma
Authors: Martinez H. , Reyes P. G. , Vergara-Sanchez J. , Contreras V. U. L. , Cisneros C. , Yousif F. B.
Published: August 2020

We present a detailed Langmuir probe, optical emission spectroscopy (OES), and quadrupole mass spectrometry (QMS) characterization of a DC CO2–H2 plasma mixture, complemented by calculations of the electron energy distribution functions (EEDFs) and ionization rates of CO2 plasma with varying H2 ratios using Boltzmann equation (BE) solver BOLSIG+, assuming a bi-Maxwellian distribution. Both the measured and calculated EEDFs as a function of the H2 concentration agreed well and showed a bi-Maxwellian distribution. The measured and calculated electron temperatures Te as a function of the increment in the H2 concentration (0–100%) increased in the range of 2.5–3.1 eV. The measured and calculated electron densities (Ne) as a function of H2 concentration exhibited the same increasing behavior (approximately 1010 cm−3), which confirms that the mixture composition directly influences the plasma-related parameters and results in a large fraction of H atoms by reaction e + H2 → H + H. An ascending Te would result in higher ionization rates (explaining the observed increase in electron densities), which agrees with the ionization rate behavior obtained by the BE calculation. Both OES and QMS techniques detected the species H (through the lines Hα, Hβ, and Hγ), CO, CO2, CO2+, O2, OH, O, C2, CO, and CO+. An analysis of the CO/CO2 and O2/CO2 ratios would clarify that OH is formed from O2 + H → OH + O rather than other reactions involving CO species. At a 100% CO2 concentration, CO and O2 formations proceed in accordance with the stoichiometry of 2CO2 → 2CO + O2.
Uncovering transitions in paleoclimate time series and the climate driven demise of an ancient civilization
Authors: Malik Nishant
Published: August 2020

We present a hybrid framework appropriate for identifying distinct dynamical regimes and transitions in a paleoclimate time series. Our framework combines three powerful techniques used independently of each other in time series analysis: a recurrence plot, manifold learning through Laplacian eigenmaps, and Fisher information metric. The resulting hybrid approach achieves a more automated classification and visualization of dynamical regimes and transitions, including in the presence of missing values, observational noise, and short time series. We illustrate the capabilities of the method through several pragmatic numerical examples. Furthermore, to demonstrate the practical usefulness of the method, we apply it to a recently published paleoclimate dataset: a speleothem oxygen isotope record from North India covering the past 5700 years. This record encodes the patterns of monsoon rainfall over the region and covers the critically important period during which the Indus Valley Civilization matured and declined. We identify a transition in monsoon dynamics, indicating a possible connection between climate change and the decline of the Indus Valley Civilization.
Small data materials design with machine learning: When the average model knows best
Authors: Vanpoucke Danny E. P. , van Knippenberg Onno S. J. , Hermans Ko , Bernaerts Katrien V. , Mehrkanoon Siamak
Published: August 2020

Machine learning is quickly becoming an important tool in modern materials design. Where many of its successes are rooted in huge datasets, the most common applications in academic and industrial materials design deal with datasets of at best a few tens of data points. Harnessing the power of machine learning in this context is, therefore, of considerable importance. In this work, we investigate the intricacies introduced by these small datasets. We show that individual data points introduce a significant chance factor in both model training and quality measurement. This chance factor can be mitigated by the introduction of an ensemble-averaged model. This model presents the highest accuracy, while at the same time, it is robust with regard to changing the dataset size. Furthermore, as only a single model instance needs to be stored and evaluated, it provides a highly efficient model for prediction purposes, ideally suited for the practical materials scientist.
Stability of forced–damped response in mechanical systems from a Melnikov analysis
Authors: Cenedese Mattia , Haller George
Published: August 2020

Frequency responses of multi-degree-of-freedom mechanical systems with weak forcing and damping can be studied as perturbations from their conservative limit. Specifically, recent results show how bifurcations near resonances can be predicted analytically from conservative families of periodic orbits (nonlinear normal modes). However, the stability of forced–damped motions is generally determined a posteriori via numerical simulations. In this paper, we present analytic results on the stability of periodic orbits that perturb from conservative nonlinear normal modes. In contrast with prior approaches to the same problem, our method can tackle strongly nonlinear oscillations, high-order resonances, and arbitrary types of non-conservative forces affecting the system, as we show with specific examples.
Computational and theoretical analysis of electron plasma cooling by resonant interaction with a microwave cavity
Authors: Kur E. , Robicheaux F. , Evetts N. , Fajans J. , Guerra A. , Hardy W. N. , Hunter E. D. , Schroeder Z. T. , Wurtele J. S.
Published: August 2020

Recent experiments demonstrated that the cyclotron cooling rate of an electron plasma in a Penning–Malmberg trap can be increased by placing the plasma in a cavity and adjusting the magnetic field to make the cyclotron motion resonant with a cavity mode. Here this physics is studied with a coupled oscillator model and analyzed both analytically and numerically. Plasma cooling performance is evaluated over a wide range of system parameters, including the number of electrons, the coupling to the local electric field, the magnetic field gradient, and the detuning between the cavity and cyclotron frequencies. Scaling the equations shows that the system is well-described by a few key dimensionless quantities.
Many-body reactive force field development for carbon condensation in C/O systems under extreme conditions
Authors: Lindsey Rebecca K. , Goldman Nir , Fried Laurence E. , Bastea Sorin
Published: August 2020

We describe the development of a reactive force field for C/O systems under extreme temperatures and pressures, based on the many-body Chebyshev Interaction Model for Efficient Simulation (ChIMES). The resulting model, which targets carbon condensation under thermodynamic conditions of 6500 K and 2.5 g cm−3, affords a balance between model accuracy, complexity, and training set generation expense. We show that the model recovers much of the accuracy of density functional theory for the prediction of structure, dynamics, and chemistry when applied to dissociative condensed phase systems at 1:1 and 1:2 C:O ratios, as well as molten carbon. Our C/O modeling approach exhibits a 104 increase in efficiency for the same system size (i.e., 128 atoms) and a linear system size scalability over standard quantum molecular dynamics methods, allowing the simulation of significantly larger systems than previously possible. We find that the model captures the condensed-phase reaction-coupled formation of carbon clusters implied by recent experiments, and that this process is susceptible to strong finite size effects. Overall, we find the present ChIMES model to be well suited for studying chemical processes and cluster formation at pressures and temperatures typical of shock waves. We expect that the present C/O modeling paradigm can serve as a template for the development of a broader high pressure–high temperature force-field for condensed phase chemistry in organic materials.
A microvolume shear cell for combined rheology and x-ray scattering experiments
Authors: Narayanan Theyencheri , Dattani Rajeev , Möller Johannes , Kwaśniewski Paweł
Published: August 2020

An experimental setup is presented for x-ray scattering studies of soft matter under shear flow that employs a low-background coaxial capillary cell coupled to a high-resolution commercial rheometer. The rotor of the Searle type cell is attached to the rheometer shaft, which allows the application of either steady or oscillatory shear of controlled stress or rate on the sample confined in the annular space between the stator and the rotor. The shearing device facilitates ultrasmall-angle x-ray scattering and ultrasmall-angle x-ray photon correlation spectroscopy measurements with relatively low scattering backgrounds. This enables the elucidation of weak structural features otherwise submerged in the background and probes the underlying dynamics. The performance of the setup is demonstrated by means of a variety of colloidal systems subjected to different rheological protocols. Examples include shear deformation of a short-range attractive colloidal gel, dynamics of dilute colloids in shear flow, distortion of the structure factor of a dense repulsive colloidal suspension, shear induced ordering of colloidal crystals, and alignment of multilamellar microtubes formed by a surfactant–polysaccharide mixture. Finally, the new possibilities offered by this setup for investigating soft matter subjected to shear flow by x-ray scattering are discussed.
Effect of trace SF6 on negative corona characteristics in SF6/N2 gas mixtures under DC voltages
Authors: He Yanliang , Sun Anbang , Zhang Xing , Xue Jianyi , Zhang Guanjun
Published: August 2020

Corona discharge will affect the performance of insulating gas, threatening the safe and reliable operation of gas-insulated power equipment. In this paper, we investigate the negative corona characteristics in SF6/N2 gas mixtures with trace SF6 [φ(SF6) ≤ 1%] under DC voltages. With decreasing SF6 content, two types of the discharge–stage transition process as a function of mean current are observed. One process is from the Townsend stage, through the pulse stage, to the breakdown stage; the other one presents a normal-glow stage between the pulse stage and the breakdown stage. The threshold of SF6 content which can change the discharge–stage transition process in SF6/N2 gas mixtures is between 0.1% and 0.15%. The lower limit of positive-ion flux in the normal-glow stage is 6–7 orders of magnitude higher than the upper limit of positive-ion flux in the Townsend stage. The variation in pulse characteristic parameters, including pulse–time parameters and pulse amplitude, with increasing SF6 content is investigated. The pulse–time parameters show a trend of decreasing first and then saturation with increasing SF6 content, while the pulse amplitude shows a slightly increasing trend. Moreover, the “return stroke” phenomenon of negative corona in SF6/N2 gas mixtures is observed through discharge light emission images. The “return stroke” phenomenon does not necessarily occur in the normal-glow stage, resulting from competition between the position of the negative-ion cloud and the negative-ion flux.
Unusual internal friction and its size dependence in nanoscale metallic glasses
Authors: Yang Gongji , Wang Risheng , Wang Mingxu , Liu Longfei , Kong Lingti , Li Jinfu
Published: August 2020

The internal friction of Cu50Zr50 metallic glass nano-pillars was investigated by using molecular dynamics simulations. An unusual non-monotonic variation of internal friction is revealed against the size of the specimen, which differs significantly from that of the bulk metallic glass. Meanwhile, by analyzing the rearranged atoms with high mobility, which play a vital role in affecting the internal friction, it is found that the rearrangement of surface atoms is more significant than that of the bulk ones, and their fraction depends on the sample size as well. With reducing the sample size, the fraction of rearranged atoms in the surface region increases, which could be described by an exponential equation. This finding suggests that the size dependence of internal friction originates directly from the different fractions of the rearranged atoms in the surface region of nano-pillars. Furthermore, a phenomenological model was established to describe the internal friction of the nano-pillars against their diameters. The presented results provide a quantitative insight into the size effect on internal friction in nanoscale metallic glasses, also shedding light on the atomistic mechanism of surface relaxation of amorphous solids.
Super-resolution and signal separation in contact Kelvin probe force microscopy of electrochemically active ferroelectric materials
Authors: Ziatdinov Maxim , Kim Dohyung , Neumayer Sabine , Collins Liam , Ahmadi Mahshid , Vasudevan Rama K. , Jesse Stephen , Ann Myung Hyun , Kim Jong H. , Kalinin Sergei V.
Published: August 2020

Imaging mechanisms in contact Kelvin probe force microscopy (cKPFM) are explored via information theory-based methods. Gaussian processes are used to achieve super-resolution in the cKPFM signal, effectively extrapolating across the spatial and parameter space. Tensor factorization is applied to reduce the multidimensional signal to the tensor convolution of the scalar functions that show a clear trending behavior with the imaging parameters. These methods establish a workflow for the analysis of the multidimensional datasets that can then be related to the relevant physical mechanisms. We also provide an interactive Google Colab notebook that goes through all the analyses discussed in the paper.
Giant magnetic field effects in donor–acceptor triads: On the charge separation and recombination dynamics in triarylamine–naphthalenediimide triads with bis-diyprrinato-palladium(II), porphodimethenato-palladium(II), and palladium(II)–porphyrin photosensitizers
Authors: Riese Stefan , Brand Jessica S. , Mims David , Holzapfel Marco , Lukzen Nikita N. , Steiner Ulrich E. , Lambert Christoph
Published: August 2020

A series of triads consisting of a triarylamine donor, a naphthalenediimide acceptor, and a palladium photosensitizer bridge was investigated for the photoinduced electron transfer processes and the spin chemistry involved. In this series, the ligand in the palladium photosensitizer was varied from bis-dipyrrinato to porphodimethenato and to a porphyrin. With the porphyrin photosensitizer, no charge separated state could be reached. This is caused by the direct relaxation of the excited photosensitizer to the ground state by intersystem crossing. The bis-dipyrrinato-palladium photosensitizer gave only a little yield (7%) of the charge separated state, which is due to the population of a metal centered triplet state and a concomitant geometrical rearrangement to a disphenoidal coordination sphere. This state relaxes rapidly to the ground state. In contrast, in the porphodimethenato-palladium triads, a long lived (μs to ms) charge separated state could be generated in high quantum yields (66%–74%) because, here, the population of a triplet metal centered state is inhibited by geometrical constraints. The magnetic field dependent transient absorption measurement of one of the porphodimethenato triads revealed a giant magnetic field effect by a factor of 26 on the signal amplitude of the charge separated state. This is the consequence of a magnetic field dependent triplet–singlet interconversion that inhibits the fast decay of the charge separated triplet state through the singlet recombination channel. A systematic comparative analysis of the spin-dependent kinetics in terms of three classical and one fully quantum theoretical methods is provided, shedding light on the pros and cons of each of them.
Jet formation and deep seal phenomena associated with inclined oil entry of rotating steel spheres
Authors: Tan Benedict C.-W.
Published: August 2020

The jet formation and deep seal phenomena following the inclined oil entry of rotating steel spheres were experimentally investigated. The results were compared with those obtained from vertical and non-rotating oil entry of the same spheres. It had been observed that the jet formation could be classified into two processes. First, a thin primary jet was formed immediately after deep seal. Second, the same jet became significantly thicker following the complete collapse of the air cavity at the oil surface. The inclined oil jet would gradually turn toward the vertical plane, while the angle between the primary jet and the quiescent oil surface was found to decrease when the Reynolds number of the spheres increased. The deep seal time was also independent of both linear and angular sphere velocities, while the vertical deep seal displacement increased with the Froude number.
Electric field induced metallic behavior in thin crystals of ferroelectric
α
-In2Se3
Authors: Rodriguez Justin R. , Murray William , Fujisawa Kazunori , Lee Seng Huat , Kotrick Alexandra L. , Chen Yixuan , Mckee Nathan , Lee Sora , Terrones Mauricio , Trolier-McKinstry Susan , Jackson Thomas N. , Mao Zhiqiang , Liu Zhiwen , Liu Ying
Published: August 2020

Ferroelectric semiconductor field effect transistors (FeSmFETs), which employ ferroelectric semiconducting thin crystals of α-In2Se3 as the channel material as opposed to the gate dielectric in conventional ferroelectric FETs (FeFETs), were prepared and measured from room to liquid-helium temperatures. These FeSmFETs were found to yield evidence for the reorientation of electrical polarization and an electric field-induced metallic state in α-In2Se3. Our findings suggest that FeSmFETs can serve as a platform for the fundamental study of ferroelectric metals as well as the exploration of potential applications of semiconducting ferroelectrics.
Observation of anomalous emissions of nonpolar a-plane MgZnO and ZnO epi-films based on XEOL and time-resolved XEOL in hybrid bunch mode
Authors: Lin Bi-Hsuan , Wu Yu-Hao , Wu Yung-Chi , Liu Wei-Rein , Lee Chien-Yu , Chen Bo-Yi , Yin Gung-Chian , Hsieh Wen-Feng , Tang Mau-Tsu
Published: August 2020

X-ray excited optical luminescence (XEOL) using an x-ray nanobeam operating in the hybrid bunch mode provides not only a sufficiently high peak power density but also high-quality temporal domain measurements for studying the luminescence dynamics of photonic materials and devices. We used these features to investigate the peculiar emission behavior of the as-grown and rapid thermal annealing (RTA)-treated a-plane MgZnO epi-films, from which an anomalous emission was observed at ∼325 nm, along with a rapid increase in near-band edge (NBE) emission with increasing x-ray irradiation time. This peculiar emission behavior was also observed in the cathodoluminescence spectra obtained under electron beam excitation. Increases in the NBE emission intensity of the RTA-treated a-plane MgZnO epi-film were observed in terms of both photoluminescence and small anomalous emissions of XEOL. This can be explained by the effective transfer of Mg atoms from interstitial sites to suitable sites as a result of RTA treatment. Based on comparison with an a-plane ZnO epi-film without Mg, we conclude that the anomalous emission peak is caused by Mg-related energy states created by the high-dose x-ray or electron beam irradiation. Furthermore, the rapid increase in NBE emission and the reduction in the long decay lifetime can be attributed to charge transfer from the Mg clusters, which are thus responsible for the anomalous emissions.
Unraveling liquid polymorphism in silicon driven out-of-equilibrium
Authors: Desgranges Caroline , Delhommelle Jerome
Published: August 2020

Using nonequilibrium molecular dynamics simulations, we study the properties of supercooled liquids of Si under shear at T = 1060 K over a range of densities encompassing the low-density liquid (LDL) and high-density liquid (HDL) forms. This enables us to generate nonequilibrium steady-states of the LDL and HDL polymorphs that remain stabilized in their liquid forms for as long as the shear is applied. This is unlike the LDL and HDL forms at rest, which are metastable under those conditions and, when at rest, rapidly undergo a transition toward the crystal, i.e., the thermodynamically stable equilibrium phase. In particular, through a detailed analysis of the structural and energetic features of the liquids under shear, we identify the range of densities, as well as the range of shear rates, which give rise to the two forms. We also show how the competition between shear and tetrahedral order impacts the two-body entropy in steady-states of Si under shear. These results open the door to new ways of utilizing shear to stabilize forms that are metastable at rest and can exhibit unique properties, since, for instance, experiments on Si have shown that HDL is metallic with no bandgap, while LDL is semimetallic with a pseudogap.
Coherent states of position-dependent mass trapped in an infinite square well
Authors: Amir Naila , Iqbal Shahid
Published: August 2020

We develop generalized coherent states based on the Gazeau–Klauder formalism for a particle with position-dependent mass trapped in an infinite square well. We study the quantum statistical properties of these states by means of the Mandel parameter and the second-order correlation function. Our analysis reveals that the constructed coherent states exhibit sub-Poissonian statistics. Moreover, theoretical investigations of wave packet revivals and fractional revivals for the pertaining system have been performed by means of the autocorrelation function and temporal evolution of probability density.
2D ferromagnetism at finite temperatures under quantum scrutiny
Authors: Vanherck Joren , Bacaksiz Cihan , Sorée Bart , Milošević Milorad V. , Magnus Wim
Published: August 2020

Recent years have seen a tremendous rise of two-dimensional (2D) magnetic materials, several of which were verified experimentally. However, most of the theoretical predictions to date rely on ab initio methods, at zero temperature and fluctuation-free, while one certainly expects detrimental quantum fluctuations at finite temperatures. Here, we present the solution of the quantum Heisenberg model for honeycomb/hexagonal lattices with anisotropic exchange interaction up to third nearest neighbors and in an applied field in arbitrary direction, which answers the question whether long-range magnetization can indeed survive in the ultrathin limit of materials, up to which temperature, and what the characteristic excitation (magnon) frequencies are, all essential to envisaged applications of magnetic 2D materials. We find that long-range magnetic order persists at finite temperature for materials with overall easy-axis anisotropy. We validate the calculations on the examples of monolayers CrI3, CrBr3, and MnSe2. Moreover, we provide an easy-to-use tool to calculate Curie temperatures of new 2D computational materials.
Experimental investigation on the propagation characteristics of internal solitary waves based on a developed piecewise dynamic mode decomposition method
Authors: Zhang Jiu-Ming , Zou Li , Sun Tie-Zhi , Wen Ze-Hua , Yu Zong-Bing
Published: August 2020

The propagation of internal solitary waves (ISWs) flowing over the submerged topography is a strongly nonlinear process. To extract the dynamic characteristics of this process, an improved dynamic mode decomposition method is proposed in this paper, which is named piecewise dynamic mode decomposition (PDMD). The innovation of this method is to split the entire evolution process into several quasi-linear segments before modal analyzing to reduce the requirements on the spatial and temporal resolutions of input measured data. A feasible criterion for linearity is introduced by combining the proper orthogonal decomposition method, which is an important basis of PDMD. The data used in the analysis are provided by the experiments conducted in a stratified wave tank. The experimental conditions are set as ISWs flowing over two typical bottom topographies. The interfacial displacement and flow field information are analyzed as the measured data. Through reconstruction and modal analysis of experimental data, the effectiveness and flexibility of PDMD are verified for the ISW problem. The physical meaning of segmentation points can be explained. Based on the results of model decomposition, the main propagation characteristics of ISWs under different conditions are discussed. The evolution of the waveform or local flow phenomena can be simplified to the superposition of linear modes with frequency information.
The effect of low-angle off-axis GaN substrate orientation on the surface morphology of Mg-doped GaN epilayers
Authors: Su Po-Yi , Liu Hanxiao , Wang Shuo , Wu Zhihao , Liu Rong , Ponce Fernando A.
Published: August 2020

The effect of low-angle off-axis GaN substrate orientation on the surface morphology of Mg-doped GaN epilayers has been studied using atomic force microscopy (AFM) and transmission electron microscopy. Undoped- and magnesium-doped GaN layers were grown on (0001) GaN surfaces tilted by 0.3°, 2°, and 4° toward a ⟨11¯00⟩ direction. AFM images show the presence of pinholes associated with threading screw dislocations originating from the substrate. Mg doping causes enhanced step-flow growth with well-defined periodic steps and a tendency to cover the pinholes. In regions far from defects, atomic-resolution imaging shows the coexistence of surface regions with different atomic step densities, i.e., with slightly different inclination, that depend on the substrate tilt angle. For low tilt (0.3°), the steps involve a single basal plane (with a height = c/2). At higher tilt, the steps involve two basal planes with a tendency toward step bunching. Cathodoluminescence spectroscopic imaging has been used to correlate the electronic properties with the thin film surface morphology, showing that step bunching reduces p-type doping efficiency.
Free energy of hydrophilic and hydrophobic pores in lipid bilayers by free energy perturbation of a restraint
Authors: Dixit Mayank , Lazaridis Themis
Published: August 2020

The free energy of pore formation in lipid bilayers has been previously calculated using a variety of reaction coordinates. Here, we use free energy perturbation of a cylindrical lipid exclusion restraint to compute the free energy profile as a function of pore radius in dimyristoylphosphatidylcholine (DMPC) and dioleoylphosphatidylcholine (DOPC) bilayers. Additionally restraining the headgroups to lie on the membrane surface allows us to also calculate the free energy profile of hydrophobic pores, i.e., cylindrical pores lined by acyl chains. For certain pore radii, the free energy of wetting of hydrophobic pores is calculated using the density bias method. It is found that wetting of hydrophobic pores becomes thermodynamically favorable at 5.0 Å for DMPC and 6.5 Å for DOPC, although significant barriers prevent spontaneous wetting of the latter on a nanosecond time scale. The free energy of transformation of hydrophilic pores to hydrophobic ones is also calculated using free energy perturbation of headgroup restraints along the bilayer normal. This quantity, along with wetting and pore growth free energies, provides complete free energy profiles as a function of radius. Pore line tension values for the hydrophilic pores obtained from the slope of the free energy profiles are 37.6 pN for DMPC and 53.7 pN for DOPC. The free energy profiles for the hydrophobic pores are analyzed in terms of elementary interfacial tensions. It is found that a positive three-phase line tension is required to explain the results. The estimated value for this three-phase line tension (51.2 pN) lies within the expected range.
Numerical simulation of the combined effects of thermophoretic motion and variable thermal conductivity on free convection heat transfer
Authors: Ashraf Muhammad , Abbas Amir , Ali Aamir , Shah Zahir , Alrabaiah Hussam , Bonyah Ebenezer
Published: August 2020

In the current research, the effect of thermophoretic motion combined with temperature-dependent thermal conductivity on natural convection flow around the surface of a sphere at several circumferential locations has been presented. The modeled nonlinear governing partial differential has been transformed into a dimensionless form with the help of appropriate non-dimensional variables. Later, the finite difference method is applied to solve the proposed model. The effect of controlling parameters, such as thermal conductivity variation parameter γ, Prandtl number Pr, Schmidt number Sc, thermophoretic coefficient k, and thermophoresis parameter Nt on the velocity field, temperature distribution, mass concentration, skin friction, rate of heat transfer, and rate of mass transfer has been highlighted. The estimations of the emerging parameters on the physical properties are displayed in graphical and in tabular forms. It has been predicted that the rise in γ, Nt, Sc, Pr, and k increases the velocity distribution, but the reverse behavior has been seen in the temperature field. The enhancement in Nt, Sc, Pr, and k boosts up the curves of mass concentration, and the rise in γ suppresses the concentration function. It has been observed that an increase in γ reduces the skin friction and the rate of mass transfer but opposite behavior of the rate of heat transfer occurs. Furthermore, increasing values of Sc cause the skin friction to lose the dominance in the rate of heat and mass transfer. It has been also noticed that increasing values of Nt strengthen the skin friction and rate of heat transfer, and attenuation occurs in the case of the rate of mass transfer.
Is single-mode lasing possible in an infinite periodic system?
Authors: Benzaouia Mohammed , Cerjan Alexander , Johnson Steven G.
Published: August 2020

In this Letter, we present a rigorous method to study the stability of periodic lasing systems. In a linear model, the presence of a continuum of modes (with arbitrarily close lasing thresholds) gives the impression that stable single-mode lasing cannot be maintained in the limit of an infinite system. However, we show that nonlinear effects of the Maxwell–Bloch equations can lead to stable systems near threshold given a simple stability condition on the sign of the laser detuning compared to the band curvature. We examine band edge (1D) and bound-in-continuum (2D) lasing modes and validate our stability results against time-domain simulations.
Electronic transport and its inelastic effects for a doped phagraphene device
Authors: Sampaio-Silva Alessandre , Maciel Correa Samuel , Silva Carlos Alberto B. , Del Nero Jordan
Published: August 2020

This work is a systematic investigation of electronic transport and inelastic effects of two-terminal devices without gates composed of zigzag and armchair phagraphene nanoribbons doped with boron nitride. It is based on a hybrid density functional theory and the nonequilibrium Green’s function method implemented in the TRANSIESTA code. The doping in the device with a zigzag conformation had a metal–semiconductor transition, symmetric eigenchannels (ECs), high transmission probability, and an evident field-effect transistor (FET) signature with two operating windows. The armchair configuration had a semiconductor–metal transition, asymmetric features in the ECs that decrease the transmission probability considerably, a switch signature for low bias, and FET behavior for bias V>0.2V. These results suggest that the impurities improve the electron transport for both edge conformations. On the other hand, inelastic transport made a smaller contribution to the current and conductance compared to elastic transport. Inelastic electron-tunneling spectroscopy showed that electron tunneling in phagraphene devices is mainly driven by elastic effects, indicating that almost all the energy of the system is conveniently used in the electronic transport and is not lost through network vibrations.
Development of ambient marine standards using long-term data: An example from Abu Dhabi
Authors: Suleiman Wael , Anbiah Rajan , Al Raisi Azza , Al Hosani Shaikha , Barber Mary , Whaley Glenn
Published: August 2020

Abu Dhabi, the capital of the United Arab Emirates, has a coastline that occupies 76% of the country’s Arabian Gulf coastline. The pressures accompanying the economic development that the country is undergoing ultimately affected the marine ecosystem including water and sediment quality. In order to protect the marine ecosystem and public health, the Environment Agency- Abu Dhabi developed ambient marine water and sediment quality standards using the long-term data collected along the coast of Abu Dhabi. Along with the data collected on 39 marine water quality and sediment parameters (hydrography, nutrients, and heavy metals), a review of best practices from jurisdictions whose approach was scientifically based and whose physical conditions were as similar as possible to those found in Abu Dhabi were used for the establishment of marine water and sediment quality limits. These promulgated ambient limits were then used to develop the marine water and sediment regulation that establish two uses of marine waters (protected and general) and an anti-degradation policy. In addition, the ambient water and sediment limits provide a bench mark to both assess trends that may indicate stress to marine flora and fauna and support the work of environmental permitting and enforcement.
Application of the Canadian Council of Ministers of the Environment Water Quality Index to assess and communicate monitoring data from coastal waters in Abu Dhabi, United Arab Emirates
Authors: Woodward Katherine P. , Rajan Anbiah , Barber Mary C. , Sullivan Elizabeth , Richkus Jennifer A.S. , Everett Kibri Hutchison , Whaley M. Glenn
Published: August 2020

The purpose of this research was to (1) identify an existing water quality index methodology that could be used in Abu Dhabi, United Arab Emirates, and (2) apply the water quality index to Abu Dhabi’s waters to communicate water quality conditions and track changes in conditions over time. The available monitoring data were reviewed to establish the types and frequencies of data available to populate an index, and a literature search was performed to identify and review existing water quality ind in use around the world. The Canadian Council of Ministers of the Environment Water Quality Index was selected and customized for use in Abu Dhabi. Using the Canadian Council of Ministers Water Quality Index, two different data aggregation methods were investigated for developing a single Emirate-wide Water Quality Index score. Finally, an alternative method for calculating indices when there are fewer than four parameters was investigated. Three Water Quality Indexs were developed for use in Abu Dhabi: Eutrophication Index, Microbial Index, and Heavy Metals (in sediment) Index. The Canadian Council of Ministers Water Quality Index methodology was found to be relatively easy to use and flexible as a building block for tailored indices, which are used to communicate marine water quality conditions to various stakeholders, including scientists, managers, policymakers, and the public.
Jet quenching parameter from a soft wall AdS/QCD model *
Authors: Zhu Xiangrong , Zhang Zi-qiang
Published: August 2020

We study the effect of chemical potential and nonconformality on the jet quenching parameter in a holographic QCD model with conformal invariance broken by background dilaton. The presence of chemical potential and nonconformality both increase the jet quenching parameter, thus enhancing the energy loss, consistently with the findings of the drag force.
Transverse momentum balance and angular distribution of

dijets in Pb + Pb collisions *
Authors: Dai Wei , Wang Sa , Zhang Shan-Liang , Zhang Ben-Wei , Wang Enke
Published: August 2020

In this study, the production of inclusive b-jet and

dijets in Pb + Pb collisions has been investigated by considering the in-medium evolution of heavy and light quarks simultaneously. The initial hard processes of inclusive b-jet and

dijets production are described using a next-to-leading order (NLO) plus parton shower Monte Carlo (MC) event generator, SHERPA, which can be well matched with the experimental data in p + p collisions. The framework uses the Langevin transport model to describe the evolution of the bottom quark. Furthermore, the collisional energy loss and higher-twist description are considered to determine the radiative energy loss from both the bottom and light quarks. We compare the theoretical simulation of the inclusive jet and b-jet

in the Pb + Pb collisions at

TeV with the experimental data and present the theoretical simulation of the momentum balance of the

dijet in the Pb + Pb collisions at

TeV along with recent CMS data for the first time. A similar trend to that seen in inclusive dijets is observed in

dijets; the distribution of the production shifts to smaller

owing to the jet quenching effect. Finally, we report the prediction of the normalized azimuthal angle distribution of the

dijet in the Pb + Pb collisions at

TeV. The medium-induced energy loss effect of the

dijets will generally suppress its production; however, the same side (

region) suffers more energy loss than the far side (

region), thus leading to suppression on the same side and enhancement on the far side in the normalized azimuthal angle distribution in A + A collisions.
Spatio-temporal dynamics in seismic exposure of Asian megacities: past, present and future
Authors: Mestav Sarica Gizem , Zhu Tinger , Pan Tso-Chien
Published: August 2020

The estimation of urban growth in megacities is a critical and intricate task for researchers and decision-makers owing to the complexity of these urban systems. Currently, the majority of megacities are located in Asia which is one of the most disaster-prone regions in the world. The high concentrations of people, infrastructure and assets in megacities create high loss potentials for natural hazards; therefore, the forecasting of exposure metrics such as built-up area is crucial for disaster risk assessment. This study aims to identify and project the dynamics of built-up area at risk using a spatio-temporal approach considering seismic hazard in three Asian megacities, namely Jakarta, Metro Manila and Istanbul. First, Landsat Thematic Mapper images were processed to obtain the built-up areas of 1995 and 2016 for Metro Manila, and of 1995 and 2018 for Jakarta and Istanbul. The SLEUTH urban growth model, a cellular automaton (CA)-based spatial model that simulates urban growth using historical geospatial data, was then employed to predict the urban growth of these megacities by 2030. Finally, seismic hazard maps obtained for 10% and 2% probabilities of exceedance were overlaid with built-up area maps. For a seismic hazard of 10% probability of exceedance in 50 years, the total urban area subjected to Modified Mercalli intensities (MMI) VIII and IX has increased nearly 65% over 35 years in Metro Manila. For Jakarta and Istanbul, the total urban area at the MMI VIII level has increased nearly 79% and 54% over 35 years, respectively. For a seismic hazard of 2% probability of exceedance in 50 years, the total urban area subjected to MMI IX has increased nearly 75%, 65% and 49% over 35 years in Jakarta, Metro Manila and Istanbul, respectively. The results show that urban growth modelling can be utilized to assess the built-up area exposed to high risk as well as to plan urban growth considering natural hazards in megacities.
Electronic and geometric stability of double titanium-doped silicon clusters
Authors: Zhang Bingwen , Wang Jun , Hu Ziyang , Ning Aifeng
Published: August 2020

We performed the genetic algorithm (GA) incorporated with density functional theory (DFT) calculations to investigate the atomic and electronic properties of a series of Ti2Si
n
(n = 3 = –24) clusters. Comprehensive consideration on the formation energy, the second difference in cluster energy and the addition energy of Si to a Ti2Si
n−1 cluster as well as the HOMO-LUMO gap, our results show that Ti2Si4 cluster is the most stable one in the series of clusters, followed by the Ti2Si13, Ti2Si21,Ti2Si15 and Ti2Si7 clusters, which can be understood by the combination of symmetry and electron shell filling rule. The silicon cage could be obviously enhanced by doping double Ti atoms making them promising nanoscale materials.
VIDHOP, viral host prediction with deep learning
Authors: Mock Florian , Viehweger Adrian , Barth Emanuel , Marz Manja
Published: August 2020

Motivation

Zoonosis, the natural transmission of infections from animals to humans, is a far-reaching global problem. The recent outbreaks of Zikavirus, Ebolavirus and Coronavirus are examples of viral zoonosis, which occur more frequently due to globalization. In case of a virus outbreak, it is helpful to know which host organism was the original carrier of the virus to prevent further spreading of viral infection. Recent approaches aim to predict a viral host based on the viral genome, often in combination with the potential host genome and arbitrarily selected features. These methods are limited in the number of different hosts they can predict or the accuracy of the prediction.

Results

Here, we present a fast and accurate deep learning approach for viral host prediction, which is based on the viral genome sequence only. We tested our deep neural network (DNN) on three different virus species (influenza A virus, rabies lyssavirus and rotavirus A). We achieved for each virus species an AUC between 0.93 and 0.98, allowing highly accurate predictions while using only fractions (100–400 bp) of the viral genome sequences. We show that deep neural networks are suitable to predict the host of a virus, even with a limited amount of sequences and highly unbalanced available data. The trained DNNs are the core of our virus–host prediction tool VIrus Deep learning HOst Prediction (VIDHOP). VIDHOP also allows the user to train and use models for other viruses.

Availability and implementation

VIDHOP is freely available under https://github.com/flomock/vidhop.

Supplementary information

Supplementary data are available at Bioinformatics online.
Conjunctival Scarring, Corneal Pannus, and Herbert’s Pits in Adolescent Children in Trachoma-endemic Populations of the Solomon Islands and Vanuatu
Authors: Butcher Robert , Tagabasoe Junely , Manemaka Joseph , Bong Annie , Garae Mackline , Daniel Lui , Roberts Chrissy , Handley Becca L , Hu Victor H , Harding-Esch Emma M , Bakhtiari Ana , Willis Rebecca , Müller Andreas , Kaldor John , Le Mesurier Richard , Mabey David , Cama Anasaini , Sokana Oliver , Taleo Fasihah , Taylor Hugh R , Solomon Anthony W
Published: August 2020

Background

In the Solomon Islands and Vanuatu, the sign trachomatous inflammation—follicular (TF) is common, but ocular infection with Chlamydia trachomatis is not. It is therefore debatable whether azithromycin mass drug administration (MDA), the recommended antibiotic treatment strategy for trachoma’s elimination as a public health problem, is necessary in this setting. We set out to estimate what proportion of adolescents were at risk of progression of trachomatous scarring.

Methods

A cross-sectional survey was undertaken of all children aged 10–14 years resident in communities identified as high-TF clusters during previous population-based mapping. Graders examined children for clinical evidence of trachomatous scarring, pannus, and Herbert’s pits (HPs) or limbal follicles in both eyes. A dried blood spot was collected from each child and tested for antibodies to C. trachomatis.

Results

A total of 492 children in 24 villages of the Solomon Islands and Vanuatu were examined. In total, 35/492 (7%) of children had limbal signs (pannus and/or HPs) plus any conjunctival scarring. And 9/492 (2%) had limbal signs and moderate or severe conjunctival scarring; 22% of children were anti-Pgp3 seropositive.

Conclusions

Few adolescents here are at risk of future complications from trachoma, supporting the conclusion that further antibiotic MDA is not currently required for trachoma elimination purposes in these settings.
‘Me and Not-Me’: Folk Songs, Narrative Perspectives, and The Gender Imaginary in Angela Carter’s Shadow Dance
Authors: Paulusma Polly
Published: August 2020

It is a little-known fact that Angela Carter was a traditional folk singer during the 1960s, that she played the English concertina, and that she co-founded a folk club in Bristol with her first husband, Paul Carter. A newly unearthed private archive of her folk song notes from the decade, which includes her musical notations and a recording of her singing, allows us to develop new understandings of her folk praxis and, when laid alongside her private journal entries, the folk album sleeve notes she penned, her undergraduate dissertation, and other unpublished papers, a whole host of possible new readings of her literary work emerges. This essay explores just one: gender fluidity in folk song performance and its impact upon Carter’s interpretations of gender identity in her debut novel, Shadow Dance. I will suggest that Carter learned gender ambiguity from her folk singing, and that her experience of singing afforded her freedoms to explore versions of sexual performance and gendered selfhood through male characters. More broadly, I will suggest that she buried musical folk song features into the structures of her writing to present her prose as a form of audial performance.
Is device-based total and domain-specific sedentary behaviour associated with psychological distress in Flemish workers?
Authors: De Cocker Katrien , Ketels Margo , Bennie Jason A , Clays Els
Published: August 2020

Background

There is increasing interest in the association between psychological distress and time spent in sedentary behaviour (e.g. sitting), a highly prevalent behaviour in modern society. The limited evidence is mixed and mainly based on studies using self-reported sedentary time. Few studies have investigated device-based total sedentary time in its association with distress. None, however, have examined device-based domain-specific sedentary time in relation to psychological distress. The aim of this study was to investigate whether device-based total and domain-specific sedentary behaviour were associated with psychological distress.

Methods

Flemish employees (n = 401; 20–64 years; 42.6% male; 83.6% had a ‘physically active occupation’) of seven organizations in service and production sectors participated. Sedentary behaviour (exposure) was assessed by two Axivity AX3 accelerometers (one placed on the thigh and one placed between the shoulders) for two to four consecutive working days. Based on diary completion, domain-specific sedentary behaviour (leisure vs. work) was assessed. The 12-item General Health Questionnaire was used to assess psychological distress (outcome). Adjusted hierarchical multiple regression models were conducted to report on the associations between total and domain-specific sedentary behaviour and psychological distress.

Results

About 35% of the sample had high levels of distress and average total sedentary time was 7.2 h/day. Device-based total sedentary behaviour [B = −0.009, 95% confidence interval (CI), −0.087 to 0.068], leisure-time (B = 0.001, 95% CI, −0.017 to 0.018) and work-related (B = 0.004, 95% CI, −0.006 to 0.015) sedentary behaviour were not significantly associated with psychological distress.

Conclusion

This cross-sectional study examining the association between device-based total and domain-specific sedentary behaviour and psychological distress among employees showed a lack of significant findings.