bluuebunny/crossref_metadata_2025 huggingface dataset:
INNOVATION AND CORRUPTION: DISSECTING CAUSAL LINKAGE USING PATENT APPLICATION INFORMATION FROM INDIA
Authors: PODDAR PRASHANT , SINGH SANJAY KUMAR
Published: July 2020

Using World Bank Enterprise Survey data on bribery and patent applications, we try to study the causal linkage between firm level innovation and corruption in India. Specifically, we try to understand if corruption impacts innovation at the firm level. Since we find that innovation and corruption are jointly determined, we propose instrumental variables regression approach to identify this causal effect. We instrument bribery by exogenously determined external audit parameter and then use a recursive bivariate probit model combined with industry-fixed effects to reach our results. Our findings suggest that bribery has an adverse impact on innovation. The results of our study are much in contrast to the existing literature, which largely supports a positive relationship between innovation and corruption.
HOW URBANIZATION AFFECTS ENERGY-ENVIRONMENT EFFICIENCY: EVIDENCE FROM CHINA
Authors: CHEN YUFENG , ZHU ZHITAO , YU XI
Published: July 2020

Energy consumption and environmental pollution are along with urban sprawling, while the impact of urbanization on energy and environment is quite controversial. The study of urbanization and energy-environmental efficiency provides a new perspective to understand the correlation between urbanization, energy consumption and environment. In this paper, a Directional Distance Function-Data Envelopment Analysis (DDF-DEA) model is employed to investigate provincial energy-environment efficiency in China from 1999 to 2017. Then the mechanism of urbanization substantially affecting the energy-environment efficiency is empirically examined from the perspective of government and market, respectively. The results indicate that China’s energy-environmental efficiency is improving, but regional differences exist and have widened since 2005; the overall impact of urbanization on China’s energy-environment efficiency is negative while the mechanism differs between different regions. Specifically, government-dominated urbanization has promoted energy-environment efficiency in the eastern region, while has a negative impact in the central and western regions; market-led urbanization has a limited positive impact on energy-environment efficiency. These conclusions proved to be robust, and are of great significance for policymakers to take full use of the positive externality of urbanization to promote the energy-environment efficiency and improve the environment.
Rashba-controlled two-electron spin-charge qubits as building blocks of a quantum computer
Authors: Kregar A. , Ramšak A.
Published: July 2020

The spin-sensitive charge oscillation, controlled by an external magnetic field, was recently proposed as a mechanism of transformations of qubits, defined as two-electron spin-charge Wannier molecules in a square quantum dot.1 The paper expands this idea by including the effects of Rashba-type spin-orbit coupling. The problem is studied theoretically by mapping the system to an analytic effective Hamiltonian for 8 low-energy states, comprising singlet and triplet on each dot diagonal. The validity of mapping is confirmed by comparing the energy and spin of full and mapped system, and also by the reproduction of charge-oscillation dynamics in the presence of magnetic flux. The newly introduced Rashba coupling significantly enriches the system dynamics, affecting the magnitude of charge oscillations and allowing the controlled transitions between singlet and triplet states due to the spin rotations, induced by spin-orbit coupling. The results indicate the possibility for use of the studied system for quantum information processing, while possible extensions of the system to serve as a qubit in a universal quantum computer, fulfilling all five Di Vincenzo criteria, is also discussed.
Hadamard parametrix of the Feynman Green’s function of a five-dimensional charged scalar field
Authors: Balakumar Visakan , Winstanley Elizabeth
Published: July 2020

The Hadamard parametrix is a representation of the short-distance singularity structure of the Feynman Green’s function for a quantum field on a curved spacetime background. Subtracting these divergent terms regularizes the Feynman Green’s function and enables the computation of renormalized expectation values of observables. We study the Hadamard parametrix for a charged, massive, complex scalar field in five spacetime dimensions. Even in Minkowski spacetime, it is not possible to write the Feynman Green’s function for a charged scalar field exactly in closed form. We, therefore, present covariant Taylor series expansions for the biscalars arising in the Hadamard parametrix. On a general spacetime background, we explicitly state the expansion coefficients up to the order required for the computation of the renormalized scalar field current. These coefficients become increasingly lengthy as the order of the expansion increases, so we give the higher-order terms required for the calculation of the renormalized stress-energy tensor in Minkowski spacetime only.
A NONLOCAL STRUCTURAL DERIVATIVE MODEL BASED ON THE CAPUTO FRACTIONAL DERIVATIVE FOR SUPERFAST DIFFUSION IN HETEROGENEOUS MEDIA
Authors: XU WEI , LIANG YINGJIE
Published: July 2020

Superfast diffusion exists in various complex anisotropic systems. Its mean square displacement is an exponential function of time proved by several theoretical and experimental investigations. Previous studies have studied the superfast diffusion based on the time-space scaling local structural derivatives without considering the memory of dynamic behavior. This paper proposes a nonlocal time structural derivative model based on the Caputo fractional derivative to describe superfast diffusion in which the structural function is a power law function of time. The obtained concentration of the diffusive particles, i.e. the solution of the structural derivative model is a double-sided exponential distribution. The derived mean square displacement is a Mittag–Leffler function of time, which generalizes the exponential case. To verify the feasibility of the model, the charge and energy transfer at nanoscale interfaces in solar cells and the dynamics of the dripplons between two graphene sheets are employed. Compared with the existing models, the fitting results indicate that the proposed model is more accurate with higher credibility. The properties of the nonlocal structural derivative model with different structural functions are also discussed.
FRACTAL ANALYSIS OF SURFACE ROUGHNESS EFFECTS ON GAS DIFFUSION IN POROUS NANOFIBERS
Authors: ZHENG QIAN , WANG HUILI , JIANG JIAN , XU CHAO
Published: July 2020

Fractal model of gas diffusion in porous nanofibers with rough surfaces is derived, in which the porous structure is assumed to be composed of a bundle of tortuous capillaries whose pore size distribution and surface roughness follow the fractal scaling laws. The analytical expression for gas relative diffusion coefficient is a function of the relative roughness and the other microstructural parameters (porosity, the fractal dimension for pore size distribution and tortuosity, the maximum and minimum pore diameter and the characteristic length). The proposed fractal model is validated by comparison with available experimental data and correlations. At the same time, the effect of microstructural parameters of porous fibrous materials on gas diffusion has been studied in detail. It is believed that the current model may be extended to porous materials other than fibrous materials.
FRACTAL DIMENSION ANALYSIS FOR ASSESSING THE HEALTH CONDITION OF A TRUSS STRUCTURE USING VIBRATION SIGNALS
Authors: MORENO-GOMEZ ALEJANDRO , MACHORRO-LOPEZ JOSE M. , AMEZQUITA-SANCHEZ JUAN P. , PEREZ-RAMIREZ CARLOS A. , VALTIERRA-RODRIGUEZ MARTIN , DOMINGUEZ-GONZALEZ AURELIO
Published: July 2020

During the last years, civil infrastructure has experienced an increasing development to satisfy the society’s demands such as communication, transportation, work and living spaces, among others. In this sense, the development and application of methods to guarantee the structure optimal operation, known as Structural Health Monitoring schemes, are necessary in order to avoid economic and human losses. Modern schemes employ the structure vibration response as any damage will modify the structure physical properties, which will be reflected in the vibration response. Thus, by measuring the waveform changes of the response, the structure condition can be determined. Considering this fact, this paper investigates the effectiveness of Katz fractal dimension, Higuchi fractal dimension, Box fractal dimension, Petrosian fractal dimension, and Sevcik fractal dimension which are nonlinear measurements to extract features of vibration signals in order to determine the health condition of a 3D 9-bay truss-type bridge. The obtained results show that the algorithms corresponding to Higuchi and Petrosian fractal dimension algorithms exceed the other nonlinear measurements in efficiency to discriminate between a healthy structure and a damage produced by corrosion.
ASSOUAD DIMENSION AND SPECTRUM OF HOMOGENEOUS PERFECT SETS
Authors: YANG JIAOJIAO , DU YALI
Published: July 2020

The homogeneous perfect sets introduced by Wen and Wu [Hausdorff dimension of homogeneous perfect sets, Acta. Math. Hungar. 107 (2005) 35–44] is an important class of Moran sets. In this paper, we obtain the Assouad dimension and Assouad spectrum formulas for homogeneous perfect set under suitable condition. In the proof an Assouad spectrum formula for a large class of fractal sets is established.
ANALYSIS OF PERMEABILITY EVOLUTION CHARACTERISTICS BASED ON DUAL FRACTAL COUPLING MODEL FOR COAL SEAM
Authors: LIU GUANNAN , YU BOMING , GAO FENG , YE DAYU , YUE FENGTIAN
Published: July 2020

In study of gas migration process in coal seam, the permeability evolution rule with time has been one of hot topics in the area of coal seam for decades. At present, in view of the time-varying rule of coal seam permeability, the influence of microstructure parameters and adsorption effect are seldom considered simultaneously. In this paper, the fractal seepage model coupled with coal deformation, and the adsorption expansion effect of coal is proposed. A multi-field coupling model is established by considering the influence of matrix and fracture structure. The influence of structural parameters and adsorption constant of main fracture on the time-varying curve of macro permeability are analyzed, including: (1) fractal dimension for fracture lengths; (2) maximum fracture length; (3) Langmuir adsorption strain constant; (4) Langmuir adsorption pressure constant. The results show that, under the influence of in situ stress and adsorption effect, the permeability of coal seam decreases with time. The present results show that the permeability is proportional to the fractal dimension for fracture lengths and the maximum fracture length. The uniformity of permeability distribution is found to be directly proportional to the pressure constant of Langmuir and inversely proportional to the volume constant of Langmuir.
Inspection Order by Importance Measure Under Imperfect Inspection
Authors: Satow Takashi
Published: July 2020

Maintenance decision making, which is based on a result of imperfect inspection, sometimes causes problems with system operation. In order to reduce opportunities of misjudgment by imperfect inspection, inspection threshold is effective. The impact of component’s failure under the system operation is an important issue on maintenance decision making. It is also important to identify the weaknesses in the system. A minimal path-cut method is a concept that can express the system structure from the functional aspect. In this paper, it derives system importance measures under imperfect inspection using minimal path-cuts, and conduct basic research on the planning of inspection execution plans according to the inspection order.
Multi-Biological Laboratory Examination Framework for the Prioritization of Patients with COVID-19 Based on Integrated AHP and Group VIKOR Methods
Authors: Albahri A. S. , Al-Obaidi Jameel R. , Zaidan A. A. , Albahri O. S. , Hamid Rula A. , Zaidan B. B. , Alamoodi A. H. , Hashim M.
Published: July 2020

Coronavirus disease (COVID-19) pandemic has a tremendous effect on people’s lives worldwide, and the number of infected patients increases daily. The healthcare sector is affected by a large number of patients with COVID-19, and a solution is urgently needed to avert the risk of deteriorating patients in terms of prioritizing patients based on their health conditions. Prioritization of patients with COVID-19 is a complex and multi-criteria decision-analysis (MCDA) problem due to (i) multiple biological laboratory examination criteria, (ii) criteria importance and (iii) trade-off amongst the criteria. This study presents a new multi-biological laboratory examination framework for prioritizing patients with COVID-19 on the basis of integrated MCDA methods. The experiment was conducted on the basis of three phases. In the first phase, patient datasets containing eight biological laboratory examination criteria for six patients with COVID-19 were derived and discussed. The outcome of this phase was used to propose a decision matrix on the basis of the intersection between “biological laboratory examination criteria” and “COVID-19 patients list”. In the second phase, the analytic hierarchy process (AHP) method was utilized to set the subjective weights for the biological laboratory examination criteria by respiratory experts. In the last phase, the VIekriterijumsko KOmpromisno Rangiranje (VIKOR) method was adopted to prioritize patients in the context of individual and group decision making (GDM). Results showed that (1) the integration of AHP–VIKOR method based on individual and GDM contexts was effective for solving prioritization problems for patients with COVID-19, and (2) the prioritization results of patients with COVID-19 showed no variation in the internal and external VIKOR GDM contexts. The proposed multi-biological laboratory examination framework can differentiate between the mild and serious or critical condition of patients with COVID-19 by prioritizing them based on integrated AHP–VIKOR methods. In conclusion, medical sectors can use the proposed framework to differentiate the health conditions of infected patients and to assign appropriate care with prompt and effective treatment.
An Improved MABAC Group Decision-Making Method Using Regret Theory and Likelihood in Probability Multi-Valued Neutrosophic Sets
Authors: Liu Peide , Cheng Shufeng
Published: July 2020

Probability multi-valued neutrosophic set (PMVNS) is a preferable tool to capture the preference and hesitancy of decision makers (DMs) and to depict inconsistent and ambiguous information. In this paper, we improve the multi-attributive border approximation area comparison (MABAC) method under the PMVNS environment and establish a three-phase multi-attribute group decision-making (MAGDM) method. Firstly, some concepts of PMVNS, traditional MABAC method and regret theory (RT) are reviewed. Then, the similarity measure for PMVNSs is defined and utilized to derive the important degree of DMs, and the likelihood of preference relations expressed by the probability multi-valued neutrosophic numbers (PMVNNs) is first presented and employed to replace the distance deviation in traditional MABAC method. Furthermore, a novel MAGDM method where the performance of alternatives is expressed by the PMVNN is established by combining the likelihood-based MABAC method and RT which considered given DMs’ behavior psychology. Finally, a case study is implemented to demonstrate the feasibility and applicability of our proposed approach.
Insights into the binding of dorzagliatin with glucokinase: A molecular dynamics simulation
Authors: Liu Wei , Yao Chenhui , Shang Qian , Liu Yuqiang , Liu Changying , Meng Fancui
Published: July 2020

Human glucokinase (GK) is a potentially attractive target for diabetes, playing a prominent role in the control of glucose homeostasis. Dorzagliatin is the first GK activator (GKA) to enter phase III clinical trial. In this study, the possible binding mode of dorzagliatin with GK was investigated via the molecular simulation method. Two other systems in the absence of dorzagliatin and glucose were also studied to disclose the roles of dorzagliatin and glucose. The outcomes revealed that dorzagliatin can create the characteristic hydrogen bonds of GKA with Arg63, and Arg63 can form hydrogen bonds with nearby residues, making a tight binding hydrogen bond network around dorzagliatin. The presence of dorzagliatin can stabilize glucokinase for a period of time, and the binding of glucose may prevent the GK conformational change to a certain extent. Our results may be beneficial to mechanism understanding of GKA, and will be useful in design of novel GKAs for treating metabolic diseases.
Automatic adjoint differentiation for gradient descent and model calibration
Authors: Goloubentsev Dmitri , Lakshtanov Evgeny
Published: July 2020

In this work, we discuss the Automatic Adjoint Differentiation (AAD) for functions of the form [Formula: see text], which often appear in the calibration of stochastic models. We demonstrate that it allows a perfect SIMD a parallelization and provides its relative computational cost. In addition, we demonstrate that this theoretical result is in concordance with numerical experiments.

a Single Input Multiple Data.
Bridge Damage Detection Using Quasi-Static Component of Moving Vehicle-Induced Dynamic Response
Authors: Chen Zhiwei , Zhou Yigui , He Wen-Yu , Liu Mengqi
Published: July 2020

The critical signal component extracted from the bridge response caused by a moving vehicle is normally used to construct damage index for damage detection. The dynamic response of bridges subjected to moving vehicle includes several components, among which the quasi-static component reflects the inherent characteristics of the bridge. In view of this, this paper presents a bridge damage detection method based on quasi-static component of the moving vehicle-induced dynamic response. First, damage-induced changes of the natural-frequency component, moving-frequency component and quasi-static component responses are investigated via a simply-supported beam bridge. The quasi-static component response is proved to be less sensitive to the moving velocity of the load and more suitable for damage detection. Subsequently, a quasi-static component response extraction method is proposed based on analytical mode decomposition (AMD) and moving average filter (MAF). The extracted quasi-static component response is further employed to localize and quantify damages. Finally, numerical simulations are conducted to examine the feasibility, accuracy and advantages of the proposed damage detection method. The results indicated that the proposed method performs well in different damage scenarios and is insensitive to the moving velocity of the load and road roughness.
A Novel Robust Remeshing Finite Element Technique for Fracture Propagation
Authors: Ramalho L. D. C. , Belinha J. , Campilho R. D. S. G.
Published: July 2020

In this work, a novel and robust remeshing algorithm for crack opening problems is proposed, combined with triangular plane stress finite elements. In the proposed algorithm, the crack tip efficiently propagates until a pre-established maximum crack length is achieved and the crack propagation direction is defined considering the maximum tangential stress criterion. The stress state at the crack tip is obtained using a weighted average of the stresses of the integration points adjacent to the crack tip, to smoothen the stress field near the crack tip. In order to achieve accurate stress fields in the vicinity of the singularity, the proposed algorithm establishes that there is always a fixed number of nodes and elements surrounding the crack tip. To verify the accuracy of the algorithm, three benchmark tests were analyzed and the solutions were compared with results available in the literature. It was observed that the proposed technique allows to maintain the meshes regular during the propagation process, significantly reducing the number of distorted elements, which solves one of the main problems when simulating crack propagation with the finite element method (FEM). Additionally, the obtained results allowed to understand that this algorithm generally leads to accurate crack paths.
Multiplicity spin, structure, and charge of iron-verdohemeoxygenase complex: A comparison study by the DFT method
Authors: Tasharofi Hamideh , Asli Maryam Daghighi , Jamaat Parisa Rajabali
Published: July 2020

Recently the three-dimensional structure of verdoheme heme oxygenase complex was revealed. However, many parameters of verdoheme heme oxygenase’s complex structure and their role and function on Heme degradation were unknown. In this work the structure of iron verdoheme in complex with heme oxygenase was compared by the density functional theory (DFT)-based B3LYP method using the 6-31G basis set. Many parameters such as charge of verdoheme and iron as central metal, electron distribution, spin multiplicity of the molecule and proximal substituents effects on verdoheme ring stabilization and their arrangement are discussed and compared for twelve different conformations of the molecules to find the most energetically stable states.
Vibration Control of a Smart Shell Reinforced by Graphene Nanoplatelets
Authors: Al-Furjan M. S. H. , Habibi Mostafa , Safarpour Hamed
Published: July 2020

Smart control and dynamic investigation of a graphene nanoplatelets reinforced composite (GPLRC) cylindrical shell surrounded by a piezoelectric layer as actuator and sensor based on a numerical solution method called generalized differential quadrature method (GDQM) are presented for the first time. The strains and stresses can be determined via the first-order shear deformable theory (FSDT). For accessing to various mass densities, thermal expansion as well as Poisson ratio, the rule of mixture is applied, although a modified Halpin–Tsai theory is used for obtaining the module of elasticity. The external voltage is applied to the sensor layer, while a proportional-derivative (PD) controller has been utilized for controlling the output of sensor. GPLRCs boundary conditions are derived through governing equations of the cylindrical shell using an energy method known as Hamilton’s principle. The outcomes show that the PD controller, viscoelastic foundation, slenderness factor ([Formula: see text]/[Formula: see text], external voltage and graphene nanoplatelets (GPLs) weight fraction have a considerable impact on the amplitude, and vibration behavior of a GPLRC cylindrical shell. As an applicable result in related industries, the parameter and consideration of the PD controller have a positive effect on the static and dynamic behaviors of the structure.
The Architecture of Co-Culture Spheroids Regulates Tumor Invasion within a 3D Extracellular Matrix
Authors: Huang Yu Ling , Shiau Carina , Wu Cindy , Segall Jeffrey E. , Wu Mingming
Published: July 2020

Tumor invasion, the process by which tumor cells break away from their primary tumor and gain access to vascular systems, is an important step in cancer metastasis. Most current 3D tumor invasion assays consisted of a single tumor cell embedded within an extracellular matrix (ECM). These assays taught us much of what we know today on how key biophysical (e.g., ECM stiffness) and biochemical (e.g., cytokine gradients) parameters within the tumor microenvironment guided and regulated tumor invasion. One limitation of the single tumor cell invasion assays was that it did not account for cell–cell adhesion within the tumor. In this paper, we developed a micrometer scale 3D co-culture spheroid invasion assay that recapitulated physiologically realistic tumor microenvironment and was compatible with microscopic imaging. Micrometer scale co-culture spheroids (1:1 ratio of metastatic breast cancer MDA-MB-231 and non-tumorigenic epithelial MCF-10A cells) were made using an array of microwells, and then were embedded within a collagen matrix in a microfluidic platform. Real time imaging of tumor spheroid invasion revealed that the spatial distribution of the two cell types within the tumor spheroid critically regulated tumor invasion. This work linked tumor architecture with tumor invasion and highlighted the importance of the biophysical cues within the bulk of the tumor in tumor invasion.
Mathematical analysis of a time-delayed model on brucellosis transmission with disease testing information
Authors: Hou Qiang , Zhang Lei , Liu Maoxing
Published: July 2020

Testing–culling is one of the important prevention and control measures considered in the study of animal infectious diseases. However, the process of finding infected animals (animal testing) is still not well studied through the kinetic model. In this paper, based on the characteristics of animal testing, a time-delayed model on brucellosis transmission is established. Under the general hypothesis of biological significance, the existence and stability of equilibria are first investigated. The results find that the global stability of equilibria depends on the basic reproduction number [Formula: see text] without the information delay: if [Formula: see text], the disease dies out; if [Formula: see text], the endemic equilibrium exists and the disease persists. Next, the impact of information delay on the dynamics of the model is analyzed and Hopf bifurcation is found in the established model when the information delay is greater than a critical value. Finally, the theoretical results are then further explained through numerical analysis and the significance of these results for the development of risk management measures is elaborated.
Qualitative properties and bifurcations of discrete-time Bazykin–Berezovskaya predator–prey model
Authors: Elsadany A. A. , Din Qamar , Salman S. M.
Published: July 2020

The positive connection between the total individual fitness and population density is called the demographic Allee effect. A demographic Allee effect with a critical population size or density is strong Allee effect. In this paper, discrete counterpart of Bazykin–Berezovskaya predator–prey model is introduced with strong Allee effects. The steady states of the model, the existence and local stability are examined. Moreover, proposed discrete-time Bazykin–Berezovskaya predator–prey is obtained via implementation of piecewise constant method for differential equations. This model is compared with its continuous counterpart by applying higher-order implicit Runge–Kutta method (IRK) with very small step size. The comparison yields that discrete-time model has sensitive dependence on initial conditions. By implementing center manifold theorem and bifurcation theory, we derive the conditions under which the discrete-time model exhibits flip and Niemark–Sacker bifurcations. Moreover, numerical simulations are provided to validate the theoretical results.
Investigating the effect of pyroptosis on the slow CD4+ T cell depletion in HIV-1 infection, by dynamical analysis of its discontinuous mathematical model
Authors: Monfared Z. , Omidi F. , Qaseminezhad Raeini Y.
Published: July 2020

HIV infection is one of the most serious causes of death throughout the world. CD4+ T cells which play an important role in immune protection, are the primary targets for HIV infection. The hallmark of HIV infection is the progressive loss in population of CD4+ T cells. However, the pathway causing this slow T cell decline is poorly understood [16].

This paper studies a discontinuous mathematical model for HIV-1 infection, to investigate the effect of pyroptosis on the disease. For this purpose, we use the theory of discontinuous dynamical systems. In this way, we can better analyze the dynamical behavior of the HIV-1 system. Especially, considering the dynamics of the system on its discontinuity boundary enables us to obtain more comprehensive results rather than the previous researches. A stability region for the system, corresponding to its equilibria on the discontinuity boundary, will be determined. In such a parametric region, the trajectories of the system will be trapped on the discontinuity manifold forever. It is also shown that in the obtained stability region, the disease can lead to a steady state in which the population of uninfected T cells and viruses will preserve at a constant level of cytokines. This means that the pyroptosis will be restricted and the disease cannot progress for a long time. Some numerical simulations based on clinical and experimental data are given which are in good agreement with our theoretical results.
Mathematical models for diseases in wildlife populations with indirect transmission
Authors: Barbera Elvira
Published: July 2020

In this paper, five different models for five different kinds of diseases occurring in wildlife populations are introduced. In all models, a logistic growth term is taken into account and the disease is transmitted to the susceptible population indirectly through an environment reservoir. The time evolution of these diseases is described together with its spatial propagation.

The character of spatial homogeneous equilibria against the uniform and non-uniform perturbations together with the occurrence of Hopf bifurcations are discussed through a linear stability analysis. No Turing instability is observed.

The partial differential field equations are also integrated numerically to validate the stability results herein obtained and to extract additional information on the temporal and spatial behavior of the different diseases.
Spatiotemporal dynamics of immunogenic tumors
Authors: Singh Teekam , Banerjee Sandip
Published: July 2020

A mathematical model, consisting of a system of two coupled reaction-diffusion partial differential equations describing the interaction between solid tumor and immune system (termed as effector cells), is proposed here. The main focus is on the analysis of the spatiotemporal dynamics of tumor cells and immune cells. The resulting system is analyzed and numerical simulations are presented. Different types of spatial patterns with respect to different initial conditions, and time are observed. Their analysis and mechanism of spatiotemporal pattern formation in immunogenic tumor are studied. Spatiotemporal perturbation around non-spatial steady state beyond the linear regime is obtained based on the analysis of higher-order perturbation terms.
Stability and Hopf bifurcation of a delayed virus infection model with latently infected cells and Beddington–DeAngelis incidence
Authors: Yang Junxian , Bi Shoudong
Published: July 2020

In this paper, the dynamical behaviors for a five-dimensional virus infection model with Latently Infected Cells and Beddington–DeAngelis incidence are investigated. In the model, four delays which denote the latently infected delay, the intracellular delay, virus production period and CTL response delay are considered. We define the basic reproductive number and the CTL immune reproductive number. By using Lyapunov functionals, LaSalle’s invariance principle and linearization method, the threshold conditions on the stability of each equilibrium are established. It is proved that when the basic reproductive number is less than or equal to unity, the infection-free equilibrium is globally asymptotically stable; when the CTL immune reproductive number is less than or equal to unity and the basic reproductive number is greater than unity, the immune-free infection equilibrium is globally asymptotically stable; when the CTL immune reproductive number is greater than unity and immune response delay is equal to zero, the immune infection equilibrium is globally asymptotically stable. The results show that immune response delay may destabilize the steady state of infection and lead to Hopf bifurcation. The existence of the Hopf bifurcation is discussed by using immune response delay as a bifurcation parameter. Numerical simulations are carried out to justify the analytical results.
Hopf bifurcation and chaos in a Leslie–Gower prey–predator model with discrete delays
Authors: Singh Anuraj , Preeti  , Malik Pradeep
Published: July 2020

In this work, a Leslie–Gower prey-predator model with two discrete delays has been investigated. The positivity, boundedness and persistence of the delayed system have been discussed. The system exhibits the phenomenon of Hopf bifurcation with respect to both delays. The conditions for occurrence of Hopf bifurcation are obtained for different combinations of delays. It is shown that delay induces the complexity in the system and brings the periodic oscillations, quasi-periodic oscillations and chaos. The properties of periodic solution have been determined using central manifold and normal form theory. Further, the global stability of the system has been established for different cases of discrete delays. The numerical computation has also been performed to verify analytical results.
Bogdanov–Takens Bifurcation in a Neutral Delayed Hopfield Neural Network with Bidirectional Connection
Authors: Achouri Houssem , Aouiti Chaouki , Hamed Bassem Ben
Published: July 2020

In this paper, a neutral Hopfield neural network with bidirectional connection is considered. In the first step, by choosing the connection weights as parameters bifurcation, the critical point at which a zero root of multiplicity two occurs in the characteristic equation associated with the linearized system. In the second step, we studied the zeros of a third degree exponential polynomial in order to make sure that except the double zero root, all the other roots of the characteristic equation have real parts that are negative. Moreover, we find the critical values to guarantee the existence of the Bogdanov–Takens bifurcation. In the third step, the normal form is obtained and its dynamical behaviors are studied after the use of the reduction on the center manifold and the theory of the normal form. Furthermore, for the demonstration of our results, we have given a numerical example.
Controllable synthesis of hollow NiSe2 spheres as an active electrocatalyst for hydrogen evolution reaction
Authors: Gao Caiyan , Peng Zhikun , Wu Xiaoyong
Published: July 2020

The design of electrocatalysts with excellent performance and low cost is of great significance for the electrocatalytic water splitting. NiSe2 has been widely concerned because of its suitable adsorption energy and adjustable electronic structure for hydrogen evolution reaction (HER). Here, a hollow spherical NiSe2 catalyst was designed and prepared by the hydrothermal method. Thanks to the unique three-dimensional (3D) open configuration and favorable active components, it exhibits superior catalytic activity for HER. It delivers an overpotential of 330[Formula: see text]mV at the current density of 10[Formula: see text]mA[Formula: see text]cm[Formula: see text], corresponding to the Tafel slope of 128[Formula: see text]mV[Formula: see text]dec[Formula: see text]. This work demonstrates that the 3D hollow structure with large specific surface and rich internal space can effectively improve the mass transfer efficiency and electron transfer. This work may provide a controllable way for the design of hollow structure catalysts.
Understanding the Earth: the contribution of Marie Tharp
Authors: Higgs Bettie Matheson
Published: July 2020

Marie Tharp worked all her life as a geoscientist, and for the most part for the recognition and benefit of her male colleagues. She was employed to assist researchers at Columbia University. Her male colleagues readily used her ingenuity and insights without giving her recognition. Marie tolerated this at first but eventually began to ask for recognition for her own work. Her most influential work was the production of physiographical maps of the ocean floor. During this work, in the 1950s, Marie was the first scientist to realize that there was a large rift running the length of the Atlantic Ocean, and she eventually demonstrated that this rift linked to the East African Rift Valley. Her male colleagues suppressed this discovery for reasons of their own, and 4 years later presented it as their own research. The work caused some key figures in the history of plate tectonics to change the direction of their research. Marie suffered in her career due to rivalries between her male colleagues. It was not until the 1990s that Marie began to be recognized nationally and internationally, and receive awards for her work.
A novel distal convoluted tubule-specific Cre-recombinase driven by the NaCl cotransporter gene
Authors: Cornelius Ryan J. , Sharma Avika , Su Xiao-Tong , Guo Jin-Jin , McMahon Jill A. , Ellison David H. , McMahon Andrew P. , McCormick James A.
Published: July 2020

Cre-lox technology has revolutionized research in renal physiology by allowing site-specific genetic recombination in individual nephron segments. The distal convoluted tubule (DCT), consisting of distinct early (DCT1) and late (DCT2) segments, plays a central role in Na+ and K+ homeostasis. The only established Cre line targeting the DCT is Pvalb-Cre, which is limited by noninducibility, activity along DCT1 only, and activity in neurons. Here, we report the characterization of the first Cre line specific to the entire DCT. CRISPR/Cas9 targeting was used to introduce a tamoxifen-inducible IRES-Cre-ERT2 cassette downstream of the coding region of the Slc12a3 gene encoding the NaCl cotransporter (NCC). The resulting Slc12a3-Cre-ERT2 mice were crossed with R26R-YFP reporter mice, which revealed minimal leakiness with 6.3% of NCC-positive cells expressing yellow fluorescent protein (YFP) in the absence of tamoxifen. After tamoxifen injection, YFP expression was observed in 91.2% of NCC-positive cells and only in NCC-positive cells, revealing high recombination efficiency and DCT specificity. Crossing to R26R-TdTomato mice revealed higher leakiness (64.5%), suggesting differential sensitivity of the floxed site. Western blot analysis revealed no differences in abundances of total NCC or the active phosphorylated form of NCC in Slc12a3-Cre-ERT2 mice of either sex compared with controls. Plasma K+ and Mg2+ concentrations and thiazide-sensitive Na+ and K+ excretion did not differ in Slc12a3-Cre-ERT2 mice compared with controls when sex matched. These data suggest genetic modification had no obvious effect on NCC function. Slc12a3-Cre-ERT2 mice are the first line generated demonstrating inducible Cre recombinase activity along the entire DCT and will be a useful tool to study DCT function.
Role of SIRT1 in HIV-associated kidney disease
Authors: Wang Xuan , Liu Ruijie , Zhang Weijia , Hyink Deborah P. , Das Gokul C. , Das Bhaskar , Li Zhengzhe , Wang Andrew , Yuan Weijie , Klotman Paul E. , Lee Kyung , He John Cijiang
Published: July 2020

Human immunodeficiency virus (HIV) infection of kidney cells can lead to HIV-associated nephropathy (HIVAN) and aggravate the progression of other chronic kidney diseases. Thus, a better understanding of the mechanisms of HIV-induced kidney cell injury is needed for effective therapy against HIV-induced kidney disease progression. We have previously shown that the acetylation and activation of key inflammatory regulators, NF-κB p65 and STAT3, were increased in HIVAN kidneys. Here, we demonstrate the key role of sirtuin 1 (SIRT1) deacetylase in the regulation of NF-κB and STAT3 activity in HIVAN. We found that SIRT1 expression was reduced in the glomeruli of human and mouse HIVAN kidneys and that HIV-1 gene expression was associated with reduced SIRT1 expression and increased acetylation of NF-κB p65 and STAT3 in cultured podocytes. Interestingly, SIRT1 overexpression, in turn, reduced the expression of negative regulatory factor in podocytes stably expressing HIV-1 proviral genes, which was associated with inactivation of NF-κB p65 and a reduction in HIV-1 long terminal repeat promoter activity. In vivo, the administration of the small-molecule SIRT1 agonist BF175 or inducible overexpression of SIRT1 specifically in podocytes markedly attenuated albuminuria, kidney lesions, and expression of inflammatory markers in Tg26 mice. Finally, we showed that the reduction in SIRT1 expression by HIV-1 is in part mediated through miR-34a expression. Together, our data provide a new mechanism of SIRT1 regulation and its downstream effects in HIV-1-infected kidney cells and indicate that SIRT1/miR-34a are potential drug targets to treat HIV-related kidney disease.
Blood Pressure Variability and Severity of Early Prognosis in Patients with Acute Pontine Infarction
Authors: Han Xinsheng , Zhang Gaocai , Liu Ning , Zhang Hongyang , Xu Jianke , Han Miao , Zhang Yun , Zhang Yan , Chen Li
Published: July 2020

Background. Increased blood pressure (BP) variability may worsen the prognosis of stroke. This study aimed at investigating the association between BP variability and early functional prognosis in patients with pontine infarction. Methods. According to types of pontine infarction, all the 137 patients were divided into two groups: 70 patients with paramedian pontine infarction (PPI) and 67 patients with deep pontine infarction (DPI). Common risk factors, 24-hour continuous blood pressure monitoring data, and the coefficient of variation were collected after admission in the hospital. Functional outcomes were evaluated with modified Rankin scale (mRS) at 3 months after discharge (favorable outcome: mRS scores ≤ 2; poor outcome: mRS scores > 2). Results. The level of Glu, HbA1c, LDL, and NIHSS scores in the PPI group was significantly higher than that in the DPI group, and the concentration of blood uric acid was lower in the PPI group. Diastolic pressure in the PPI group is significantly higher than that in the DPI group, and coefficient of variation (CV) of systolic pressure in PPI is higher when compared with DPI ((88.77 ± 1.71) mmHg vs. (80.74 ± 1.31) mmHg; (11.54 ± 0.35) vs. (10.24 ± 0.25)). In multivariate analyses, the CV of systolic pressure, diastolic pressure, NIHSS scores, and the paramedian pontine infarction was independently associated with 3-month clinical outcome (OR = 1.94, 95% CI = 1.252–2.994, P=0.003; OR = 1.08, 95% CI = 1.002–1.166, P=0.04; OR = 1.58, 95% CI = 1.164–2.159, P=0.003; OR = 9.87, 95% CI = 1.045–32.193, P=0.04). Conclusion. In conclusion, increased 24-hour (BP) variability, NIHSS scores, and paramedian pontine were associated with early poor prognosis in patients with acute pontine infarction.
Secondary Metabolites of Saussurea costus Leaf Extract Induce Apoptosis in Breast, Liver, and Colon Cancer Cells by Caspase‐3‐Dependent Intrinsic Pathway
Authors: Shati Ali A. , Alkahtani Mohammed A. , Alfaifi Mohamed Y. , Elbehairi Serag Eldin I. , Elsaid Fahmy G. , Prasanna Rajagopalan , Mir Mushtaq A.
Published: July 2020

Background. Apoptosis, a major form of programmed cell death, plays a vital role in regulating tissue development and maintenance of homeostasis in eukaryotes. Apoptosis can occur via a death receptor‐dependent extrinsic or a mitochondrial‐dependent intrinsic pathway and can be induced by various chemotherapeutic agents. In this study, the anticancer activity of Saussurea costus and its mode of intervention in human cancer cells of breast, colon, and liver were investigated. Results. In this study, the bioactives of S. costus leaves were extensively extracted in five solvents of different polarity. The cytotoxicity and anticancer effect of the extracted secondary metabolites were investigated against breast (MCF‐7), liver (HepG2), and colon (HCT116) cancer cell lines using a Sulphorhodamine B (SRB) assay. Secondary metabolites extracted using hexane, methanol, ethyl acetate, and chloroform had the highest cytotoxicity and thus the greatest anticancer effect on all the cancer cell lines tested (IC50; ranging from 0.25 to 2.5 μg/ml), while butanol was comparatively less active (IC50; ranging from 23.2 to 25.5 μg/ml). Further investigation using DNA flow cytometry and fluorescent microscopy revealed that the extract arrested the cells in the G1 phase of cell cycle and induced apoptosis. Furthermore, the elevated expression level of proapoptotic proteins and decreased expression level of antiapoptotic proteins confirmed that the intrinsic (mitochondrial) pathway was involved in mediating the apoptosis of cancer cells upon treatment with S. costus extract. These results altogether suggest that S. costus could be a potential anticancer agent. Conclusion. These results suggest that the S. costus extract is the potential source of the secondary metabolites that could be used as anticancer agent to treat diverse cancers of breast, colon, and liver.
Bactericidal Effect and Anti-Inflammatory Activity of Cassia garettiana Heartwood Extract
Authors: Panthong Sumalee , Itharat Arunporn , Naknarin Suchada , Kuropakornpong Pranporn , Ooraikul Buncha , Sakpakdeejaroen Intouch
Published: July 2020

Natural products are used as alternative drugs in traditional medicine to treat infection and inflammation and relieve pain. Heartwood of Cassia garettiana Craib has been investigated as an ingredient in Thai traditional medicine for anti-HIV protease, but there is no report on its antibacterial and anti-inflammatory activities. The objectives of this study were to investigate the anti-inflammatory and antibacterial activities, time-kill profile, and main active constituents of an ethanolic extract of C. garettiana heartwood. The study followed the generally accepted experimental design. All tests were investigated in triplicate. The heartwood of C. garettiana was extracted by maceration with 95% EtOH. The antibacterial activity of the extract and its chemical constituents were determined by their MIC values using resazurin as an indicator. Time-kill profile was determined at 0, 2, 4, 6, 8, 10, 12, and 24 hrs and expressed as log CFU/mL. The anti-inflammatory activity of the extract and its chemical components was investigated by their inhibiting effect on IL-6 and TNF-α production by ELISA. The ethanolic extract was analyzed for its chemical constituents by HPLC technique. The ethanolic extract showed both dose- and time-dependent bactericidal effects against Staphylococcus aureus, methicillin-resistance Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhi, Salmonella Typhimurium, Klebsiella pneumoniae, and Shigella dysenteriae with MIC values of 312.5, 312.5, 312.5, 1,250, 2,500, 625, 625, 2,500, and 625 μg/mL, respectively. It showed an inhibiting effect on IL-6 production at concentrations of 12.5 to 100 μg/mL. The main active chemical constituent of C. garettiana was piceatannol that showed antibacterial activity against all test bacteria except P. aeruginosa. C. garettiana showed a broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacteria. Piceatannol and resveratrol from the plant strongly inhibited IL-6 production. Based on these results, we concluded that the ethanolic extract of C. garettiana showed both an antibacterial activity and inhibition of IL-6. Piceatannol is the active constituent of the extract and showed anti-inflammatory and antibacterial activities against Gram-negative and Gram-positive bacteria.