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Altered heart rate variability and pulse-wave velocity after spinal cord injury

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World Journal of Clinical Cases 2022年第27期10卷 9680-9692页

作者： Hsi-Kai Tsou Kuan-Chung Shih Yueh-Chiang Lin Yi-Ming Li Hsiao-Yu Chen Functional Neurosurgery Division Neurological InstituteTaichung Veterans General HospitalTaichung 404Taiwan Department of Rehabilitation Jen-Teh Junior College of MedicineNursing and ManagementMiaoli County 356Taiwan College of Health National Taichung University of Science and TechnologyTaichung 403Taiwan College of Medicine National Chung Hsing UniversityTaichung 402Taiwan research assistant The Rong Sing Medical FoundationTaichung 404Taiwan research assistant Neurological InstituteTaichung Veterans General HospitalTaichung 404Taiwan research assistant Department of NursingNational Taichung University of Science and TechnologyTaichung 403Taiwan graduate Institute of Applied Science and Technology National Taiwan University of Science and TechnologyTaipei 106Taiwan Department of Nursing National Taichung University of Science and TechnologyTaichung 403Taiwan

BACKGROUND Heart rate variability(HRV) and pulse-wave velocity(PWV),indicators of cardiac function,are altered in patients with spinal cord injury(SCI),suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients.No study has simultaneously investigated HRV and PWV in the same patients.AIM To evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.METHODS In this cross-sectional pilot study,patients with(n = 60) and without SCI(n = 60) were recruited from December 7,2019 to January 21,2020.Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000 P.Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.RESULTS We observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals,square root of the mean sum of squared successive risk ratio interval differences,physical stress index,total power,very-low frequency,low frequency,high frequency,and arterial elasticity.CONCLUSION Patients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without,suggesting that SCI may increase cardiac function loading.

关键词： Acceleration plethysmography Cardiac function Heart rate variability Pulse wave velocity Spinal cord injury

The effect of top managers'years of experience on innovation

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International Journal of Innovation Studies 2023年第3期7卷 226-235页

作者： James Okrah Bridget Irene research Engineer Graduate School of Economics and ManagementUral Federal UniversityYekaterinburgRussia CMI Fellow IHEA Fellow assistant Professor of Entrepreneurship Course Director BA Enterprise and Entrepreneurship Coventry UniversityCoventryCV15DLUK

Managers'characteristics have been identified to have an influence on how they perceive innovation.This study examines the role of top managers'experience and how it influences their propensity to innovate.It employs a logit model to analyze data from the World Bank's Enterprise Surveys,primarily from small-and medium-sized enterprises in Russia.We justify the positive effect of managers'years of experience as an influential factor of enterprises'innovativeness in developing countries.The results show that top managers'years of experience directly affect innovation.

关键词： Russia Innovation Top-level management experience SMEs Firms Bureaucracy Weak institutions

Chinese Yuan after Chinese Exchange Rate System Reform

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China & World Economy 2006年第6期14卷 39-57页

作者： Eiji Ogawa Michiru Sakane graduate Student Graduate School of Commerce and Management Hitotsubashi University Kunitachi Tokyo and Research Assistant of RIETI.

In this paper, the actual exchange rate policy conducted by the Chinese government after the Chinese exchange rate system reform on 21 July 2005 is investigated. Also, the long-run effect is investigated, including the Balassa-Samuelson effect on the Chinese yuan. It was found that the Chinese government generated a statistically significant but small change in exchange rate policy during the sample period until 25 January 2006. It was not identified that the Chinese monetary authority is adopting the currency basket system because the change is too small in the economic sense. It is indicated that the Chinese government should take account of the productivity growth of countries composing the currency basket in order to operate a currency basket regime.

关键词： Chinese exchange rate system reform currency basket system productivity Balassa-Samuelson effect

Characterization of particle size and settling velocity of cohesive sediments affected by a neutral exopolymer

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International Journal of Sediment research 2012年第4期27卷 473-485页

作者： Xiao-ling TAN Guo-ping ZHANG Hang YIN Allen H.REED Yoko FURUKAWA graduate research assistant Department of Civil ＆ Environmental EngineeringLouisiana State University Department of Civil & Environmental Engineering Louisiana State University graduate research assistant Department of Civil & Environmental EngineeringLouisiana State University research Scientist Seafloor Sciences BranchNaval Research LaboratoryStennis Space Center

In natural waters,exopolymers or extracellular polymeric substances(EPS) exuded by microorganisms interact with clay particles,resulting in the flocculation of clays and hence alteration to the properties of suspended cohesive sediments.To investigate and further understand how neutral EPS affect cohesive sediment transport and the final sediment yield,an experimental study was conducted on laboratory-prepared clay and guar gum(used as an analog for neutral EPS) suspensions to characterize EPS-induced flocculation and the settling velocity of resultant floes.Four different clays consisting of kaolinite,illite,Ca-montmorillonite,and Na-montmorillonite were studied to examine the influence of different layer charges on clay flocculation induced by neutral EPS.Floc size was determined by a laser particle size analyzer,and settling velocity estimated by analyzing the time-series floc settling images captured by an optical microscope.Results indicate that neutral EPS promote clay-EPS flocculation for all four clays with the particle/floc size significantly increased from～0.1-60μm to as large as～600μm.Clays' layer charge has a profound influence on the clay-EPS flocculation.With the same floc size,the settling velocity of clay-EPS flocs is typically smaller than that of pure clay flocs,which is attributed to the reduced density of flocs caused by the EPS. However,for flocs of the same composition(e.***.pure clay or hybrid clay-EPS mixture),the settling velocity increases with size.The fractal dimension of these clay-EPS flocs estimated from settling velocity ranges from 1.39 to 1.47,which are smaller than that of pure clay flocs,indicating that these flocs are less compacted than the pure clay flocs.

关键词： Clay Exopolymer Flocculation Fractal dimension Particle size Settling velocity

Efficient Orbit Propagation of Orbital Elements Using Modified Chebyshev Picard Iteration Method

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Computer Modeling in Engineering & Sciences 2016年第1期111卷 65-81页

作者： J.L.Read A.Bani Younes J.L.Junkins graduate research assistant Texas A&M UniversityCollege StationTXUSA. assistant Professor Khalifa UniversityAbu DhabiUAE. Distinguished Professor Texas A&M UniversityCollege StationTXUSA.

This paper focuses on propagating perturbed two-body motion using orbital elements combined with a novel integration technique.While previous studies show that Modified Chebyshev Picard Iteration(MCPI)is a powerful tool used to propagate position and velocity,the present results show that using orbital elements to propagate the state vector reduces the number of MCPI iterations and nodes required,which is especially useful for reducing the computation time when including computationally-intensive calculations such as Spherical Harmonic gravity,and it also converges for>5.5x as many revolutions using a single segment when compared with cartesian propagation.Results for the Classical Orbital Elements and the Modified Equinoctial Orbital Elements(the latter provides singularity-free solutions)show that state propagation using these variables is inherently well-suited to the propagation method chosen.Additional benefits are achieved using a segmentation scheme,while future expansion to the two-point boundary value problem is expected to increase the domain of convergence compared with the cartesian case.MCPI is an iterative numerical method used to solve linear and nonlinear,ordinary differential equations(ODEs).It is a fusion of orthogonal Chebyshev function approximation with Picard iteration that approximates a long-arc trajectory at every iteration.Previous studies have shown that it outperforms the state of the practice numerical integrators of ODEs in a serial computing environment;since MCPI is inherently massively parallelizable,this capability is expected to increase the computational efficiency of the method presented.

关键词： Propagation Integration Orbital Mechanics Classical Elements Modified Equinoctial Chebyshev Picard Iteration MCPI Polynomials Initial Value Problem IVP.

Modeling and Measurement of a Tunable Acoustoelastic System

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Sound & Vibration 2018年第3期52卷 12-17页

作者： Deborah Fowler Garrett Lopp Dhiraj Bansal Ryan Schultz Matthew Brake Micah Shepherd Undergraduate Student University of MassachusettsLowell01854 graduate research assistant University of Central FloridaOrlandoFL32816 graduate Student University of Colorado BoulderBoulderCO 80309 Sandia National Laboratories PO Box 5800-MS0557AlbuquerqueNM87123 assistant Professor William Marsh Rice University6100 Main StMS 321HoustonTX 77005 assistant research Professor The Pennsylvania State UniversityPO Box 30State CollegePA 16804

Acoustoelastic coupling occurs when a hollow structure’s in-vacuo mode aligns with an acoustic mode of the internal cavity.The impact of this coupling on the total dynamic response of the structure can be quite severe depending on the similarity of the modal frequencies and shapes.Typically,acoustoelastic coupling is not a design feature,but rather an unintended result that must be remedied as modal tests of structures are often used to correlate or validate finite element models of the uncoupled structure.Here,however,a test structure is intentionally designed such that multiple structural and acoustic modes are well-aligned,resulting in a coupled system that allows for an experimental investigation.First,coupling in the system is identified using a measure termed the magnification factor.Next,the structural-acoustic interaction is measured.Modifications to the system demonstrate the dependency of the coupling on changes in the mode shape and frequency proximity.This includes an investigation of several practical techniques used to decouple the system by altering the internal acoustic cavity,as well as the structure itself.These results show that acoustic absorption material effectively decoupled the structure while structural modifications,in their current form,proved unsuccessful.Readily available acoustic absorptive material was effective in reducing the coupled effects while presumably adding negligible mass or stiffness to the structure.

关键词： Structural-acoustic interaction coupled modes acoustic absorption acoustic modes modal testing

Disbond detection with piezoelectric wafer active sensors in RC structures strengthened with FRP composite overlays

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Earthquake Engineering and Engineering Vibration 2003年第2期2卷 213-223页

作者： Victor Giurgiutiu Kent Harries Michael Petrou Joel Bost Josh B.Quattlebaum Department of Mechanical Engineering University of South CarolinaUSA Associate Professor Department of Civil and Environmental Engineering University of South CarolinaUSA Assistant Professor Department of Civil and Environmental Engineering University of South CarolinaUSA Associate Professor Department of Mechanical Engineering University of South CarolinaUSA Undergraduate Research Assistant Department of Civil and Environmental Engineering University of South CarolinaUSA Graduate Research Assistant

The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.

关键词： FRP composite overlays composite strengthening and rehabilitation structural health monitoring piezoelectric wafer active sensors E/M impedance aging infrastructure disbond damage PWAS

Active control of highway bridges subject to a variety of earthquake loads

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 253-263页

作者： Ryan Mitchell Young-Jin Cha Yeesock Kim Aniket Anil Mahajan Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USAGraduate Research Assistant Department of Civil Engineering University of Manitoba Winnipeg MB R3L5V6 Canada Assistant Professor Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USA Department of Civil and Environmental Engineering Worcester Polytechnic Institute (WPI) Worcester MA 01609-2280 USA Graduate Research Assistant

In this paper, a wavelet-fi ltered genetic-neuro-fuzzy(WGNF) control system design framework for response control of a highway bridge under various earthquake loads is discussed. The WGNF controller is developed by combining fuzzy logic, discrete wavelet transform, genetic algorithms, and neural networks for use as a control algorithm. To evaluate the performance of the WGNF algorithm, it is tested on a highway bridge equipped with hydraulic actuators. It controls the actuators installed on the abutments of the highway bridge structure. Various earthquakes used as input signals include an artifi cial earthquake, the El-Centro, Kobe, North Palm Springs, Turkey Bolu, Chi-Chi, and Northridge earthquakes. It is proved that the WGNF control system is effective in mitigating the vibration of the highway bridge under a variety of seismic excitation.

关键词： structural control wavelet transform genetic algor

Ductility demands on buckling-restrained braced frames under earthquake loading

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Earthquake Engineering and Engineering Vibration 2003年第2期2卷 255-268页

作者： Larry A.Fahnestock Richard Sause James M.Ricles Le-Wu Lu Department of Civil and Environmental Engineering ATLSS CenterLehigh UniversityBethlehemPennsylvaniaUSA Graduate Research Assistant Department of Civil and Environmental Engineering ATLSS CenterLehigh UniversityBethlehemPennsylvaniaUSA Professor

Accurate estimates of ductility demands on buckling-restrained braced frames(BRBFs)are crucial to performance-based design of BRBFs.An analytical study on the seismic behavior of BRBFs has been conducted at the ATLSS Center,Lehigh University to prepare for an upcoming experimental program.The analysis program DRAIN-2DX was used to model a one-bay,four-story prototype BRBF including material and geometric nonlinearities.The buckling- restrained brace(BRB)model incorporates both isotropic and kinematic hardening.Nonlinear static pushover and time- history analyses were performed on the prototype BRBF.Performance objectives for the BRBs were defined and used to evaluate the time-history analysis results.Particular emphasis was placed on global ductility demands and ductility demands on the BRBs.These demands were compared with anticipated ductility capacities.The analysis results,along with results from similar previous studies,are used to evaluate the BRBF design provisions that have been recommended for codification in the United States.The results show that BRB maximum ductility demands can be as high as 20 to 25.These demands significantly exceed those anticipated by the BRBF recommended provisions.Results from the static pushover and time- history analyses are used to demonstrate why the ductility demands exceed those anticipated by the recommended provisions. The BRB qualification testing protocol contained in the BRBF recommended provisions is shown to be inadequate because it requires only a maximum ductility demand of at most 7.5.Modifications to the testing protocol are recommended.

关键词： buildings buckling-restrained braced frames buckling-restrained braces structural response seismic response ductility demand seismic codes and standards