bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible transit routing model considering passengers’ willingness to pay
Authors: Pei Mingyang , Lin Peiqun , Liu Ronghui , Ma Yingying
Published: January 2019

This study proposes an alternative flexible transit model with two levels of bus stops, A level and B level. A‐level bus stops are fixed, while B‐level bus stops are flexible and provide service only when passengers indicate a strong willingness to pay (WTP). This fare structure encourages passengers to choose bus stops with their mobile phones or computers. An optimisation model of 0–1 integer‐programming is formulated based on whether certain B‐level stops can be serviced. With a numerical example, the authors compare the performance of the proposed traversing method and a tabu search algorithm, both of which are adapted to solve the model. Finally, a real case is provided to evaluate the proposed transit system against comparable systems (e.g. a fixed‐route transit system and a taxi service), and the result shows that the flexible transit routing model will help both passengers and bus companies, thus creating a win–win situation.
IPT system for tail‐free household appliances in the smart home system
Authors: Xia Chenyang , Liu Limin , Liu Yuling , Ma Zhixun
Published: January 2019

Inductive power transfer (IPT) is a new power supply technology for household appliances to eliminate the effects of sparks and wires. Besides, the smart home is a popular intelligent system to connect the facilities in the home. To combine the advantages of IPT technology and smart home system perfectly, the transmission of the control signal is as important as the transmission of power for IPT system. This work proposes a method that makes the power and control signal transmission synchronously from the supply side to receiving end to achieve the wireless power supply and the intelligent control for household appliances such as televisions, air conditioners, air purifiers etc. In the proposed method, the fundamental and harmonic components of the inverter output voltage are used as the power carrier and the signal carrier, respectively. One is to supply power to household appliances and the other is to transmit a control signal to them. On the basis of this method, the features of harmonics such as low energy and high frequency are well used, which enable both stable power transmission and high‐speed signal transmission. The effectiveness of the proposed method is verified by an experimental platform of kW level.
GA–PSO approach for optimising space‐vector PWM control sequence
Authors: Ning Yong , Dai Yuxing , Peng Zishun
Published: January 2019

Space‐vector pulse width modulation (SVPWM) provides several degrees of freedom, which can be optimised to improve the harmonic performance of the three‐phase inverter. Genetic algorithm (GA) and immune algorithm (IA) are the two classical probabilistic optimisation algorithms, which are simple in structure and do not need an accurate mathematical model. However, the optimisation accuracy and reliability are low when they optimise the high‐dimensional non‐linear problem, such as SVPWM control sequence of the three‐phase inverter. To cope with these problems, a genetic algorithm–particle swarm optimisation (GA–PSO) is proposed here, which introduces the mutation of GA into discrete PSO. The global and local optimisation ability of the algorithm is greatly improved by the introduction of mutation operation. The results of MATLAB/SIMULINK simulation show that the weighted total harmonic distortion (WTHD) by the optimal SVPWM control sequence based on GA–PSO is 0.199%, which is much better than that of the PSO, IA, and GA. The average generation number of GA–PSO is only 1/500 of IAs. Further experimental data verify that the WTHD by the optimal SVPWM control sequence based on GA–PSO is lower than that of conventional SVPWM and IA.
Method for predicting the remaining life of oil–paper insulation system based on stochastic degradation process
Authors: Zhang Mingze , Liu Ji , Liao Lilin , Chen Qingguo , Qi Pengshuai , Chen Xin
Published: January 2019

The service life of a transformer depends on the ageing degree of the internal oil–paper insulation. In order to reliably predict the remaining service life of oil–paper insulation for a single transformer, this study proposes a method based on monitoring the performance degradation data of oil–paper insulation. In this study, the remaining life prediction model of oil–paper insulation is established according to the Wiener stochastic process. The parameters of the model are iteratively updated by using the Bayesian rule and maximum expectation algorithm. The objective of remaining service life prediction of transformer oil–paper insulation is achieved. In the laboratory, multiple groups of oil–paper insulation samples undergo an ageing test at 130°C. Certain amount of performance degradation data is obtained by continuously monitoring the oil–paper insulation. Along with the prediction method of remaining life, the accuracy of the remaining life prediction of transformer oil–impregnated paper is verified when the model parameters are updated. This is a significant guiding factor for predicting the remaining life through the performance degradation data of the continuously operating transformer.
Effect mechanism of non‐ideal flow field on acoustic field in gas ultrasonic flowmeter
Authors: Zheng Dandan , Lv Sheng‐Hong , Mao Yang
Published: January 2019

Gas ultrasonic flowmeters are widely used in natural gas measurement. In order to achieve high accuracy, it is meaningful to study interaction mechanism between flow field and acoustic field. In this study, effects of non‐ideal flow on ultrasonic propagation are discussed. Firstly, a flow‐acoustic coupling model is established based on COMSOL and its feasibility is verified by experiments. In order to be more in line with actual working condition, flow field is obtained by CFD simulation instead of theoretical formula calculation. Secondly, with this method, two typical non‐ideal flows which often exist in real application are mainly analysed, including vortices near transducers and bend flows. The acoustic trajectory offsets, transit time, sound pressure and measurement errors are compared with results of ideal flow field. It is shown that errors will increase 10% caused by vortices near transducers, and increase 13% caused by bend flows. Besides, when passing through vortices near transducers with negative flow, trajectory offsets are opposite to flow direction. Finally, some suggestions for flowmeter design are proposed to improve measurement performance of gas ultrasonic flowmeter.
The Duistermaat-Heckman formula with application to circle actions and Poincaré q-polynomials in twisted equivariant K-theory
Authors: Bytsenko A. A. , Chaichian M. , Gonçalves A. E.
Published: January 2019

In this paper, we deduce the sketch of proof of the Duistermaat-Heckman formula and investigate how the known Duistermaat-Heckman result could be specialized to the symplectic structure on the orbit space. The theorems of localization in equivariant cohomology not only provide us with beautiful mathematical formulas and stimulate achievements in algorithmic computations but also promote progress in theoretical and mathematical physics. We present the elliptic genera and the characteristic q-series for the circle actions and twisted equivariant K-theory, with the case of the symmetric group of n symbols separately analyzed. We show that the Poincaré q-polynomials admit presentation in terms of the Patterson-Selberg (or the Ruelle-type) spectral functions.
Graph rules for the linked cluster expansion of the Legendre effective action
Authors: Banerjee R. , Niedermaier M.
Published: January 2019

Graph rules for the linked cluster expansion of the Legendre effective action Γ[ϕ] are derived and proven in D ≥ 2 Euclidean dimensions. A key aspect is the weight assigned to articulation vertices which is itself shown to be computable from labeled tree graphs. The hopping interaction is allowed to be long ranged and scale dependent, thereby producing an in principle exact solution of Γ[ϕ]’s functional renormalization group equation.
On a parabolic-parabolic system with gradient dependent chemotactic coefficient and consumption
Authors: Wang Hengling , Li Yuxiang
Published: January 2019

This paper investigates a parabolic-parabolic system with a gradient dependent chemotactic coefficient and consumption of chemoattractant under homogeneous boundary conditions of Neumann type, in a bounded domain Ω⊂Rn (n≥2) with a smooth boundary, 1 < p < 2. It is proved that if initial data satisfy u0∈C0(Ω¯), v0∈W1,q(Ω)∩(W2,n+2n(Ω),Ln+2n(Ω))nn+2,n+2n for some q > n and 0<‖v0‖L∞(Ω)<14K, then the model admits at least one global weak solution for n<8−2(p−1)p−1 and possesses at least one global renormalized solution for n≥8−2(p−1)p−1. Here, K≔supξ≥0ξ(1+ξ)2⁡ln(1+ξ) is positive and finite.
Chlorine evolution reaction electrocatalysis on RuO2(110) and IrO2(110) grown using molecular-beam epitaxy
Authors: Kuo Ding-Yuan , Paik Hanjong , Nelson Jocienne N. , Shen Kyle M. , Schlom Darrell G. , Suntivich Jin
Published: January 2019

We report the electrocatalysis of the chlorine evolution reaction (CER) on well-defined RuO2(110) and IrO2(110) surfaces. RuO2 and IrO2 are known for their capabilities to catalyze the CER. Until now, the CER measurements have only been reported on well-defined RuO2 surfaces and only at high Cl− concentrations. We present the CER measurement and the role of Cl− at lower concentration on single-orientation RuO2(110) and IrO2(110) films. We find that RuO2(110) is two orders of magnitude more active than IrO2(110). Moreover, we observe the correlation between the CER activity and the Oad formation potential on RuO2 and IrO2, supporting the prior suggestion that the Oad is the active site for the CER. We further use the reaction order analysis to support the Volmer-Heyrovsky mechanism of the CER, which was previously suggested from the Tafel slope analysis. Our finding highlights the importance of the surface Oad species on oxides for the CER electrocatalysis and suggests the electrochemical formation of Clad on Oad (for example, Cl− + Oad ↔ OClad + e−) as the crucial step in the CER electrocatalysis.
Visible astro-comb filtered by a passively stabilized Fabry-Perot cavity
Authors: Ma Yuxuan , Meng Fei , Liu Yizhou , Zhao Fei , Zhao Gang , Wang Aimin , Zhang Zhigang
Published: January 2019

We demonstrate a compact 29.3 GHz visible astro-comb covering the spectrum from 560 nm to 700 nm. A 837 MHz Yb:fiber laser frequency comb phase locked to a Rb clock served as the seed comb to ensure the frequency stability and high side mode suppression ratio. After the visible super-continuum generation, a Fabry-Perot cavity based on ultra-low expansion glass was utilized to filter the comb teeth. The mirrors were home-made complementary chirped mirrors pair with zero net-dispersion and high reflection to guarantee no mode skipping. Those filtered comb teeth were clearly resolved in an astronomical spectrograph of 49 000 resolution, exhibiting sharp line shape, zero noise floor, and uniform exposure amplitude.
Effect of surface-bound sulfide on oxygen reduction reaction on Pt: Breaking the scaling relationship and mechanistic insights
Authors: Wang Yan-Yan , Chen De-Jun , Allison Thomas C. , Tong YuYe J.
Published: January 2019

A combined in situ electrochemical attenuated total reflection-surface enhanced IR absorption spectroscopy, microkinetic simulation, and density functional theory calculation study shows that not only can the adsorbed sulfide disproportionally affect the surface binding of OOH* (EOOH*) vs OH* (EOH*), i.e., breaking the original scaling relationship of pure metals (Ir, Pd, Pt, Au), to enhance oxygen reduction reaction (ORR) activity but can also be used as a reaction pathway alternating species to help deepen our mechanistic understanding of ORR.
Exploring the binding mechanism between human profilin (PFN1) and polyproline-10 through binding mode screening
Authors: Zhang Leili , Bell David R. , Luan Binquan , Zhou Ruhong
Published: January 2019

The large magnitude of protein-protein interaction (PPI) pairs within the human interactome necessitates the development of predictive models and screening tools to better understand this fundamental molecular communication. However, despite enormous efforts from various groups to develop predictive techniques in the last decade, PPI complex structures are in general still very challenging to predict due to the large number of degrees of freedom. In this study, we use the binding complex of human profilin (PFN1) and polyproline-10 (P10) as a model system to examine various approaches, with the aim of going beyond normal protein docking for PPI prediction and evaluation. The potential of mean force (PMF) was first obtained from the time-consuming umbrella sampling, which confirmed that the most stable binding structure identified by the maximal PMF difference is indeed the crystallographic binding structure. Moreover, crucial residues previously identified in experimental studies, W3, H133, and S137 of PFN1, were found to form favorable hydrogen bonds with P10, suggesting a zipping process during the binding between PFN1 and P10. We then explored both regular molecular dynamics (MD) and steered molecular dynamics (SMD) simulations, seeking for better criteria of ranking the PPI prediction. Despite valuable information obtained from conventional MD simulations, neither the commonly used interaction energy between the two binding parties nor the long-term root mean square displacement correlates well with the PMF results. On the other hand, with a sizable collection of trajectories, we demonstrated that the average and minimal rupture works calculated from SMD simulations correlate fairly well with the PMFs (R2 = 0.67), making this a promising PPI screening method.
Realization of rhombohedral, mixed, and tetragonal like phases of BiFeO3 and ferroelectric domain engineering using a strain tuning layer on LaAlO3(001) substrate
Authors: Saj Mohan M. M. , Bandyopadhyay Soumya , Jogi Tushar , Bhattacharya Saswata , Ramadurai Ranjith
Published: January 2019

BiFeO3 (BFO), a room temperature multiferroic, undergoes a series of structural transformations under varying strain conditions by utilizing appropriate substrates for a specific strain condition. In this study, epitaxial thin films of BFO were grown on La0.7Sr0.3MnO3±δ (LSMO), a strain tuning layer on LaAlO3[LAO (001)] substrates, using pulsed laser ablation. LSMO layers of varying thicknesses from 2 nm to 20 nm were grown followed by a BFO layer of a fixed thickness (20 nm). A strained layer of ∼2 nm thick LSMO stabilizes the tetragonal like phase of BFO. Increasing the thickness of the LSMO layer to 10 nm results in a mixed phase with rhombohedral (R) and tetragonal (T) domains, and a further increment of the LSMO layer thickness to 20 nm stabilizes the rhombohedral phase of BFO. The tetragonal phase with weak monoclinic distortion possessed 180° domains with dominant out-of-plane polarization components. However, the mixed phase (R + T) possessed various plausible polarization components in both out-of-plane and in-plane directions. Further, a thermodynamically consistent model based on the phase field approach was implemented to investigate the role of strain on the formation of domain patterns with various polarization components and piezoelectric coefficients. The simulated domain structure exhibited a similar transformation on the dominant polarization components as observed in experiments across different phases of BFO. Our simulations show that the elastic constraint along the z-direction enhances the tetragonality of BFO. The piezoelectric (d33) coefficient was found to be ∼46 pm/V for the 20 nm mixed phase BFO, which was nearly a 200% increment compared to the single phase BFO thin films on LAO.
On the permeability of colloidal gels
Authors: Gelb Lev D. , Graham Alan L. , Mertz Alex M. , Koenig Peter H.
Published: January 2019

We reexamine and refine analytical theories for permeability in colloidal networks, with particular focus on constants and identification of approximations. The new theories are compared against numerical simulations of Stokes flow through the networks and reveal nearly quantitative power-law predictions for both pore size and permeability at low volume fractions, with systematic deviations observed only at high volume fractions. Comparison with two previously published experimental data sets yields mixed results: in one case, very good agreement is found, while in the other, only the scaling is correctly predicted. In fractal gel networks, the permeability is commonly modeled as a power-law function of volume fraction, with the fractal dimension of the network determining the power-law exponent. To quantitatively probe the influence of gel structure on permeability, we investigate this relation in structures generated by diffusion-limited cluster aggregation (DLCA) and reaction-limited cluster aggregation (RLCA) and, for contrast, non-overlapping uniform random dispersions of particles. Geometric analyses are used to determine network pore size distributions, fractal dimensions, and percolation characteristics. High-fidelity simulations of the slow viscous flow of Newtonian fluids are used to obtain first-principles-based velocity and fields and hence network permeabilities. Interestingly, the effective pore size that determines permeability is found to be somewhat larger than that measured by a method based on the insertion of spherical probes. Empirical inclusion of a fractal dimension dependence on volume fraction is found to yield quantitative results for permeabilities over the entire volume fraction range studied, in both DLCA and RLCA materials.
Stability analysis of a flexible rotor partially filled with two liquid phases
Authors: Wang Guangding , Yuan Huiqun
Published: January 2019

This paper deals with the dynamic stability of a flexible rotor partially filled with two liquid phases. On the basis of the Navier-Stokes equations for the incompressible flow, a two-dimensional analytical model is developed for fluid motion. The perturbation method is employed to obtain the linearized Navier-Stokes and continuity equations. According to the boundary conditions of fluid motion, the fluid force exerted on the rotor is calculated. Then, combining the structural static equilibrium equation with the equations describing the fluid forces, the whirling frequency equation of the system, which is used to predict the system stability, is obtained. The stability and critical spinning speed of the coupled fluid-structure system are analyzed. To demonstrate the validity of the developed model, the analysis results are compared with the results reported in the previous study. The two analysis results are in good agreement. Finally, the effects of some main parameters on system stability are discussed.
Deactivation of silicon surface states by Al-induced acceptor states from Al–O monolayers in SiO2
Authors: Hiller Daniel , Jordan Paul M. , Ding Kaining , Pomaska Manuel , Mikolajick Thomas , König Dirk
Published: January 2019

Al–O monolayers embedded in ultrathin SiO2 were shown previously to contain Al-induced acceptor states, which capture electrons from adjacent silicon wafers and generate a negative fixed charge that enables efficient Si-surface passivation. Here, we show that this surface passivation is just in part attributed to field-effect passivation, since the electrically active interface trap density Dit itself at the Si/SiO2 interface is reduced by the presence of the acceptor states. For sufficiently thin tunnel-SiO2 films between the Si-surface and the Al–O monolayers, Dit is reduced by more than one order of magnitude. This is attributed to an interface defect deactivation mechanism that involves the discharge of the singly-occupied dangling bonds (Pb0 defects) into the acceptor states, so that Shockley-Read-Hall-recombination is drastically reduced. We demonstrate that the combined electronic and field-effect passivation allows for minority carrier lifetimes in excess of 1 ms on n-type Si and that additional H2-passivation is not able to improve that lifetime significantly.
Potentials with identical scattering properties below a critical energy
Authors: Loran Farhang , Mostafazadeh Ali
Published: January 2019

A pair of scattering potentials are called α-equivalent if they have identical scattering properties for incident plane waves with wavenumber k ≤ α (energy k2 ≤ α2). We use a recently developed multidimensional transfer-matrix formulation of scattering theory to obtain a simple criterion for α-equivalence of complex potentials in two and three dimensions.
Flow separation control over a rounded ramp with spanwise alternating wall actuation
Authors: Ni Weidan , Lu Lipeng , Fang Jian , Moulinec Charles , Emerson David R. , Yao Yufeng
Published: January 2019

An implicit large-eddy simulation is carried out to study turbulent boundary-layer separation from a backward-facing rounded ramp with active wall actuation control. This method, called spanwise alternating distributed strips control, is imposed onto the flat plate surface upstream of a rounded ramp by alternatively applying out-of-phase control and in-phase control to the wall-normal velocity component in the spanwise direction. As a result, the local turbulence intensity is alternatively suppressed and enhanced, leading to the creation of vertical shear-layers, which is responsible for the presence of large-scale streamwise vortices. These vortices exert a predominant influence on the suppression of the flow separation. The interaction between the large-scale vortices and the downstream recirculation zone and free shear-layer is studied by examining flow statistics. It is found that in comparison with the non-controlled case, the flow separation is delayed, the reattachment point is shifted upstream, and the length of the mean recirculation zone is reduced up to 8.49%. The optimal control case is achieved with narrow in-phase control strips. An in-depth analysis shows that the delay of the flow separation is attributed to the activation of the near-wall turbulence by the in-phase control strips and the improvement of the reattachment location is mainly due to the large-scale streamwise vortices, which enhance the momentum transport between the main flow and separated region.
Fuzzy adaptive multi-mode sliding mode control for precision linear stage based on floating stator
Authors: Fang Jiwen , Zhong Wei , Li Chong , Zhao Zhong , Wang Michael Yu
Published: January 2019

This paper outlines a precision motion stage actuated by using a voice coil motor with a floating stator. For getting good performance, a multi-mode sliding mode control (MMSMC) was designed to operate this linear motion stage. MMSMC contains two sliding mode controllers: a sliding-mode control (SMC) and an integral sliding-mode control. The switching of two SMCs will be activated according to the setting error threshold. In order to eliminate the chattering phenomenon, a soft switching control is developed to replace the signum function with a smooth function. To obtain improved performance, a fuzzy controller and an adaptive controller are introduced into the MMSMC to form a fuzzy adaptive multi-mode sliding mode control (FAMMSMC). The fuzzy control is adopted to tune the slope of the sliding mode function, and the gain of the switching control is tuned according to the adaptive law. The results of the experiments are provided to make a comparison with the FAMMSMC, MMSMC, and proportional-integral-derivative control. The experimental results show that good positioning and tracking performance can be provided by using FAMMSMC.
Reducing deposition of encrustation in ureteric stents by changing the stent architecture: A microfluidic-based investigation
Authors: Mosayyebi A. , Lange D. , Yann Yue Q. , Somani B. K. , Zhang X. , Manes C. , Carugo D.
Published: January 2019

Ureteric stents are clinically deployed to retain ureteral patency in the presence of an obstruction of the ureter lumen. Despite the fact that multiple stent designs have been researched in recent years, encrustation and biofilm-associated infections remain significant complications of ureteral stenting, potentially leading to the functional failure of the stent. It has been suggested that “inactive” side-holes of stents may act as anchoring sites for encrusting crystals, as they are associated with low wall shear stress (WSS) levels. Obstruction of side-holes due to encrustation is particularly detrimental to the function of the stent, since holes provide a path for urine to by-pass the occlusion. Therefore, there is an unmet need to develop novel stents to reduce deposition of encrusting particles at side-holes. In this study, we employed a stent-on-chip microfluidic model of the stented and occluded ureter to investigate the effect of stent architecture on WSS distribution and encrustation over its surface. Variations in the stent geometry encompassed (i) the wall thickness and (ii) the shape of side-holes. Stent thickness was varied in the range 0.3-0.7 mm, while streamlined side-holes of triangular shape were evaluated (with a vertex angle in the range 45°-120°). Reducing the thickness of the stent increased WSS and thus reduced the encrustation rate at side-holes. A further improvement in performance was achieved by using side-holes with a triangular shape; notably, a 45° vertex angle showed superior performance compared to other angles investigated, resulting in a significant increase in WSS within “inactive” side-holes. In conclusion, combining the optimal stent thickness (0.3 mm) and hole vertex angle (45°) resulted in a ∼90% reduction in encrustation rate within side-holes, compared to a standard design. If translated to a full-scale ureteric stent, this optimised architecture has the potential for significantly increasing the stent lifetime while reducing clinical complications.
Shooting at the nanoscale: Collection and acceleration of nanowires with an external electric field
Authors: Farain K. , Esfandiar A. , Moshfegh A. Z.
Published: January 2019

We report an approach for collecting, charging, and exceedingly fast motion of silver nanowires (Ag NWs) using an external static electric field. With a proper choice of suspension medium, dispersed Ag NWs can be efficiently driven to align and accumulate vertically on the edges of two parallel gold microelectrodes on a glass substrate surface by dielectrophoresis. Then, at sufficiently high electric fields (>2.0×105 V/m), these NWs break at the electrode contact point while carrying some net charge. Afterwards, they immediately accelerate in the field direction and, despite an extremely low Reynolds number for the motion of NWs in viscous liquids, move with high speeds (>25  mm/s) toward the counter electrode. By solving the appropriate equation of motion, the amount of the net charge on the NWs in the beginning of the motion is estimated as ∼1×10−14 C. The described NW-shooting mechanism can be employed to construct a NW “gun” for piercing soft thin membranes at nanoscale. Furthermore, we show that the interplay of the competing dielectrophoretic and electric field forces leads to interesting dynamics for the NWs.
Quantification of nonlinear absorption in ternary As-Sb-Se chalcogenide glasses
Authors: Pradhan P. , Khan Pritam , Aswin J. R. , Adarsh K. V. , Naik R. , Das N. , Panda A. K.
Published: January 2019

In this article, we studied intensity dependent third order nonlinear optical response in ternary As40Sb7Se53 and As40Sb10Se50 chalcogenide glasses by employing the nanosecond Z-scan technique. At low intensities, we observed saturable absorption in As40Sb7Se53 which makes a remarkable transition to reverse saturable absorption at higher intensities. On the other hand, when the Sb concentration increased in As40Sb10Se50, saturable absorption disappears and the sample exhibits only two-photon absorption. Experimental results further indicate that the strong two-photon absorption in our samples can be exploited to fabricate high performance solid state optical limiting devices for the next generation all-optical network.
Families of reversing and non-reversing Taylor vortex flows between two co-oscillating cylinders with different amplitudes
Authors: Riahi Mehdi , Aniss Saïd , Ouazzani Touhami Mohamed
Published: January 2019

This paper deals with the centrifugal instability of time-modulated Taylor-Couette flow for the case in which the inner and outer cylinders are co-oscillating around zero mean with the angular velocities Ωin = Ω0 cos(ωt) and Ωout = εΩ0 cos(ωt), respectively (Ω0, ω, and ε denote, respectively, the amplitude, the frequency of the modulated rotation, and the amplitudes ratio). The small-gap equations for the stability of this flow with respect to axisymmetric disturbances are derived and solved on the basis of Floquet theory. We recover in the case ε = 0 where the outer cylinder is stationary while the inner is modulated the two well-known reversing and non-reversing Taylor vortex flows. Attention is focused on the evolution of these time-dependent flows when one allows the oscillation of the outer cylinder. It turns out that an increase in the parameter ε leads to the discovery of families of reversing and non-reversing flows and other interesting bifurcation phenomena including codimension-two bifurcation points. In addition, a proper tuning of this parameter ε provides a control of the onset of instability as well as the nature of the primary bifurcation. Moreover, it is shown that when ε > 1, the instability is suppressed in low frequencies and the flow is always stable in good agreement to what is obtained by a quasi-steady approach where transient instability is detected. This latter is attributed to the fluid inertia taking place when the cylinders are reversing their rotation’s direction. However, no effect of the parameter ε is observed in high frequencies where the instability develops in thin boundary Stokes layers near the oscillating cylinders.
Checking the Salpeter enhancement of nuclear reactions at intermediate coupling in asymmetric mixtures
Authors: Clérouin Jean , Arnault Philippe , Desbiens Nicolas , White Alexander J. , Collins Lee A. , Kress Joel D. , Ticknor Christopher
Published: January 2019

We investigate the plasma enhancement of nuclear reactions in the intermediate coupling regime using orbital free molecular dynamics (OFMD) simulations. Mixtures of H-Cu and H-Ag serve as prototypes of simultaneous weak and strong couplings due to the charge asymmetry. Of particular importance is the partial ionization of Cu and Ag and the free electron polarization captured by OFMD simulations. By comparing a series of OFMD simulations at various concentrations and constant pressure to multi-component hyper-netted chain (MCHNC) calculations of effective binary ionic mixtures, we set a general procedure for computing enhancement factors. The MCHNC procedure allows extension to very low concentrations (5% or less) and to very high temperatures (few keV) unreachable by the simulations. Enhancement factors for nuclear reaction rates extracted from the MCHNC approach are compared with the Salpeter theory in the weak and strong coupling regimes, and a new interpolation is proposed.
New normalized Rortex/vortex identification method
Authors: Dong Xiangrui , Gao Yisheng , Liu Chaoqun
Published: January 2019

A new vortex identification criterion, named ΩR, is proposed for the normalization of Rortex, using the idea of the Omega method (Ω). ΩR is a normalized function from 0 to 1, which measures the relative rotation strength on the plane perpendicular to the local rotation axis. The advantages of the proposed ΩR method can be summarized as follows: (1) ΩR is from 0 to 1 and can be further used in statistics and correlation analysis as a physical quantity. (2) ΩR can distinguish the rotational vortices from the shear layers, discontinuity structures, and other non-physical structures. (3) ΩR is quite robust and can be always set as 0.52 to capture vortex structures in different cases and at different time steps.
Enhancement of resistive switching performance by introducing a thin non-stoichiometric CeO2-x switching layer in TiO2-based resistive random access memory
Authors: Ismail Muhammad , Nisa Shafqat-Un , Rana Anwar Manzoor , Akbar Tahira , Lee Jinju , Kim Sungjun
Published: January 2019

By introducing a thin non-stoichiometric CeO2-x switching layer between the high oxygen affinity metal TaN top electrode and the TiO2 layer in a TaN/CeO2-x/TiO2/Pt bilayer (BL) device, it is possible to enhance the endurance characteristics and overcome the reliability issue. Compared with a single layer device, a BL device significantly enhances the number of direct current overswitching cycles to >1.2 × 104, non-destructive retention (>104 s), and switching uniformity. A TaON interface layer is formed which served as a reservoir of oxygen ions (O2−) in the SET-process and acts as an O2− supplier to refill the oxygen vacancies in the RESET-process and so plays a key role in the formation and rupture of conductive filaments. This study demonstrates that simply introducing a thin non-stoichiometric CeO2-x switching layer into TiO2-based devices can facilitate the enhancement of the endurance property for future nonvolatile memory applications.
Seamless global positioning system/inertial navigation system navigation method based on square-root cubature Kalman filter and random forest regression
Authors: Xiong Yufeng , Zhang Yu , Guo Xiaoting , Wang Chenguang , Shen Chong , Li Jie , Tang Jun , Liu Jun
Published: January 2019

In this paper, a seamless navigation dual-model based on Square-Root Cubature Kalman Filter (SRCKF) and Random Forest Regression (RFR) is developed to enhance the performance of the Global Positioning System (GPS)/Inertial Navigation System (INS) integrated navigation system. By using the proposed method, the system can ensure seamless navigation ability even during GPS signal outages. In the proposed dual-model, sub-model 1 that directly relates the specific force of INS to the measurement of filter and sub-model 2 that directly relates the cubature points and innovation of SRCKF to the error caused by filter are established. Combined with SRCKF and RFR algorithms, the dual-model system can predict and estimate the velocity and position of the vehicle seamlessly when GPS signals are blocked. Field test data are collected to evaluate the proposed solution, and the experimental results show that the model proposed has obvious improvement in navigation accuracy by comparison. The prominent advantages of the proposed seamless navigation method include the following: (i) the proposed dual-model can effectively provide corrections to standalone INS during GPS outages, which outperforms traditional widely used single model; (ii) the proposed combination of SRCKF and RFR achieves better performance in the prediction of INS errors than other combination algorithms.
Methanogenic potential of commonly utilised South African subtropical and temperate grass species as influenced by nitrogen fertilisation
Authors: du Toit Cornelius J. L. , van Niekerk Willem A. , Meissner Heinz H. , Erasmus Lourens J. , Morey Liesl
Published: January 2019

The aim of the study was to evaluate the effect of nitrogen (N) fertilisation on certain quality parameters and in vitro total gas and methane production of improved grass species commonly used as fodder species in South Africa. Treatments included seven grass species representing two photosynthetic pathways (C3 and C4) with three levels of N fertilisation (0, 50 and 100kg N ha–1). Plants were grown in a greenhouse and N was applied in a single application after a simulated defoliation. Sample material was harvested by hand after an 8-week regrowth period. Grass species and rate of N fertiliser both had effects (P<0.05) on the nutritive value and in vitro organic matter digestibility of the selected species. Crude protein concentration increased (P<0.05) and neutral detergent fibre concentration tended to decrease as the level of N fertilisation increased for both C3 and C4 species. Generally, no effect was found of N fertilisation on in vitro total gas or methane production; however, increasing the level of N fertiliser increased (P<0.05) the methanogenic potential (in vitro methane/in vitro total gas production) of D. glomerata, F. arundinacea and C. ciliaris after a 24-h incubation period but no significant effects were reported after a 48-h incubation period.
MMseqs2 desktop and local web server app for fast, interactive sequence searches
Authors: Mirdita Milot , Steinegger Martin , Söding Johannes
Published: January 2019

The MMseqs2 desktop and web server app facilitates interactive sequence searches through custom protein sequence and profile databases on personal workstations. By eliminating MMseqs2’s runtime overhead, we reduced response times to a few seconds at sensitivities close to BLAST.

Availability and implementation

The app is easy to install for non-experts. GPLv3-licensed code, pre-built desktop app packages for Windows, MacOS and Linux, Docker images for the web server application and a demo web server are available at https://search.mmseqs.com.

Supplementary information

Supplementary data are available at Bioinformatics online.
Incidence and Correlates of Sexually Transmitted Infections Among Black Men Who Have Sex With Men Participating in the HIV Prevention Trials Network 073 Preexposure Prophylaxis Study
Authors: Hightow-Weidman Lisa B , Magnus Manya , Beauchamp Geetha , Hurt Christopher B , Shoptaw Steve , Emel Lynda , Piwowar-Manning Estelle , Mayer Kenneth H , Nelson LaRon E , Wilton Leo , Watkins Phaedrea , Whitfield Darren , Fields Sheldon D , Wheeler Darrell
Published: January 2019

Background

The HIV Prevention Trials Network (HPTN) Study 073 (HPTN 073) assessed the feasibility, acceptability, and safety of preexposure prophylaxis (PrEP) for black men who have sex with men (BMSM). The purpose of this analysis was to characterize the relationship between PrEP uptake and use and incident sexually transmitted infections (STIs) among participants enrolled in HPTN 073.

Methods

A total of 226 human immunodeficiency virus (HIV)–uninfected BMSM were enrolled in 3 US cities; all participants received client-centered care coordination (C4) and were offered daily oral PrEP. Participants were followed for 12 months with STI testing (rectal and urine nucleic acid amplification test for gonorrhea and chlamydia, rapid plasma reagin for syphilis) conducted at baseline, week 26, and week 52. Logistic regression was used to examine associations between STI incidence and PrEP uptake. Generalized estimating equations were used to evaluate associations between age, PrEP acceptance, sexual behaviors, and incident STIs.

Results

Baseline STI prevalence was 14.2%. Men aged <25 years were more likely to have a baseline STI (25.3% vs 6.7%; odds ratio [OR], 4.39; 95% confidence interval [CI:, 1.91, 10.11). Sixty participants (26.5%) acquired ≥1 STI during follow-up; the incidence rate was 34.2 cases per 100 person-years (95% CI, 27.4, 42.9). In adjusted analyses, baseline STI diagnosis (OR, 4.23; 95% CI, 1.82, 9.87; P < .001) and additional C4 time (OR, 1.03; 95% CI, 1.00, 1.06; P = .027) were associated with having an incident STI. STI incidence was not associated with PrEP acceptance or adherence.

Conclusions

While we found higher rates of STIs in younger BMSM, overall rates of STI were lower than in prior PrEP trials, with no increase over time. BMSM with STIs at PrEP initiation may require additional interventions that target STI acquisition risk.

Clinical Trials Registration

NCT01808352.
Toxin Enzyme Immunoassays Detect Clostridioides difficile Infection With Greater Severity and Higher Recurrence Rates
Authors: Guh Alice Y , Hatfield Kelly M , Winston Lisa G , Martin Brittany , Johnston Helen , Brousseau Geoffrey , Farley Monica M , Wilson Lucy , Perlmutter Rebecca , Phipps Erin C , Dumyati Ghinwa K , Nelson Deborah , Hatwar Trupti , Kainer Marion A , Paulick Ashley L , Karlsson Maria , Gerding Dale N , McDonald L Clifford
Published: January 2019

Background

Few data suggest that Clostridioides difficile infections (CDIs) detected by toxin enzyme immunoassay (EIA) are more severe and have worse outcomes than those detected by nucleic acid amplification tests (NAATs) only. We compared toxin- positive and NAAT-positive-only CDI across geographically diverse sites.

Methods

A case was defined as a positive C. difficile test in a person ≥1 year old with no positive tests in the prior 8 weeks. Cases were detected during 2014–2015 by a testing algorithm (specimens initially tested by glutamate dehydrogenase and toxin EIA; if discordant results, specimens were reflexed to NAAT) and classified as toxin positive or NAAT positive only. Medical charts were reviewed. Multivariable logistic regression models were used to compare CDI-related complications, recurrence, and 30-day mortality between the 2 groups.

Results

Of 4878 cases, 2160 (44.3%) were toxin positive and 2718 (55.7%) were NAAT positive only. More toxin-positive than NAAT-positive-only cases were aged ≥65 years (48.2% vs 38.0%; P < .0001), had ≥3 unformed stools for ≥1 day (43.9% vs 36.6%; P < .0001), and had white blood cell counts ≥15 000 cells/µL (31.4% vs 21.4%; P < .0001). In multivariable analysis, toxin positivity was associated with recurrence (adjusted odds ratio [aOR], 1.89; 95% confidence interval [CI], 1.61–2.23), but not with CDI-related complications (aOR, 0.91; 95% CI, .67–1.23) or 30-day mortality (aOR, 0.95; 95% CI, .73–1.24).

Conclusions

Toxin-positive CDI is more severe, but there were no differences in adjusted CDI-related complication and mortality rates between toxin-positive and NAAT-positive-only CDI that were detected by an algorithm that utilized an initial glutamate dehydrogenase screening test.
What is the best graft to supplement the bilateral internal thoracic artery to the left coronary system? A meta-analysis
Authors: Di Mauro Michele , Lorusso Roberto , Di Franco Antonino , Foschi Massimiliano , Rahouma Mohamed , Soletti Giovanni , Calafiore Antonio M , Gaudino Mario
Published: January 2019

This meta-analysis was designed to assess the effect of the use of arterial conduits (ACs) versus great saphenous vein (GSV) grafts as a third conduit for revascularization of the right coronary artery system, in addition to the bilateral internal mammary artery on the left coronary artery. PubMed and OVID’s version of MEDLINE were searched from January 2000 to September 2017 for relevant publications. The primary end point was the long-term mortality rate. The secondary end point was early mortality, defined as either in-hospital death or death within 30 days after the operation. Meta-regression was used to evaluate the effect of female gender and diabetes on the primary and secondary outcomes. A total of 10 studies (4121 patients) were selected for the systematic review and meta-analysis comparing ACs (1619) versus the GSV (2502), 6 (2548) comparing the GSV (2548) versus the right gastroepiploic artery (1023) and 5 comparing the GSV (2548) versus the radial artery (596). The pooled analysis did not show any difference between ACs and the GSV in terms of long-term mortality rates [hazard ratio (HR) = 0.75, 95% confidence interval (CI) = 0.56–1.01; P = 0.061]. When using the leave-one-out analysis, after the exclusion of 1 study (outlier), ACs were significantly associated with lower long-term mortality rates (HR = 0.67, 95% CI = 0.54–0.83; P < 0.001). When the results were stratified according to the type of study, no differences with regard to long-term results were found between ACs and the GSV, either in the pooled analysis of the 6 propensity score-matched studies (HR = 0.69, 95% CI = 0.43–1.08; P = 0.107) or in the pooled analysis of the 4 non-propensity score-matched studies (HR = 0.88, 95% CI = 0.62–1.23; P = 0.438). Again, when the outlier was excluded, the pooled analysis of the propensity score-matched studies confirmed that ACs were associated with lower long-term mortality rates (HR = 0.58, 95% CI = 0.43–0.80; P < 0.001). Comparisons between the GSV and either the right gastroepiploic artery or the radial artery showed similar results. No publication bias was found. This meta-analysis is the first to compare the GSV to the radial artery and the right gastroepiploic artery for right coronary artery grafting in patients receiving a bilateral internal mammary artery to left coronary artery. The choice of a third AC seems to be preferable in order to achieve better long-term survival.
Eavesdropping on the conversation between immune cells and the skin epithelium
Authors: Bukhari Shoiab , Mertz Aaron F , Naik Shruti
Published: January 2019

The skin epithelium covers our body and serves as a vital interface with the external environment. Here, we review the context-specific interactions between immune cells and the epithelium that underlie barrier fitness and function. We highlight the mechanisms by which these two systems engage each other and how immune–epithelial interactions are tuned by microbial and inflammatory stimuli. Epithelial homeostasis relies on a delicate balance of immune surveillance and tolerance, breakdown of which results in disease. In addition to their canonical immune functions, resident and recruited immune cells also supply the epithelium with instructive signals to promote repair. Decoding the dialogue between immunity and the epithelium therefore has great potential for boosting barrier function or mitigating inflammatory epithelial diseases.
A comparison between childhood and adult onset systemic lupus erythematosus adjusted for ethnicity from the 1000 Canadian Faces of Lupus Cohort
Authors: Kim Hyein , Levy Deborah M , Silverman Earl D , Hitchon Carol , Bernatsky Sasha , Pineau Christian , Smith C Doug , Tucker Lori , Petty Ross , Arbillaga Hector , Zummer Michel , Hudson Marie , Fortin Paul , Huber Adam M , Chedeville Gaelle , Peschken Christine , Pope Janet E
Published: January 2019

Objective

Childhood-onset SLE (cSLE) manifests differently than adult-onset SLE (aSLE). This study determined whether ethnic differences contribute to the differences in clinical presentation between the two groups.

Methods

This cross-sectional study used data from a multi-centred registry from eight adult and four paediatric Canadian centres gathered at study entry. We compared the frequency of clinical manifestations and autoantibodies between aSLE and cSLE. For those with a significant difference, a multivariable logistic regression was performed, adjusting for ethnicity, SLE onset (cSLE vs aSLE), disease duration and centre. Disease activity and damage between aSLE and cSLE were compared after stratifying by disease duration.

Results

Of 552 aSLE subjects, 502 (90.9%) were female and 381 (69.0%) were Caucasian. Mean age at diagnosis was 37.0 ± 13.6 years and disease duration 10.9 ± 9.6 years. Of 276 cSLE subjects, 231 (83.7%) were female and 101 (36.6%) were Caucasian. Mean age at diagnosis was 12.7 ± 3.3 years and disease duration 5.6 ± 8.2 years. In multivariable regression analysis, aSLE was associated with decreased odds of having a neurologic disorder (odds ratio = 0.49) and increased odds of having aCL antibodies (odds ratio = 1.85). Disease activity and damage accrual scores were higher in aSLE than cSLE within the same disease duration strata, although the differences were not clinically significant. Ethnicity was not associated with any differences in clinical manifestations or autoantibody frequency between aSLE and cSLE.

Conclusion

Although a crude comparison of aSLE and cSLE yielded several differences in clinical symptoms and autoantibodies, this difference was not attributable to ethnic differences between aSLE and cSLE.