bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Design of Underwater Shells With Active Stiffeners
Authors: Akl W. , Ruzzene M. , Baz A.
Published: November 2020

The optimal design parameters of fluid-loaded shells, provided with actively controlled stiffeners, are determined using a rational multi-criteria optimization approach. The adopted approach aims at simultaneously minimizing the shell vibration, associated sound radiation, weight of the stiffening rings, the control energy, and the cost of the shell/stiffeners assembly while maximizing the controllability and observability indices.

A finite element model is presented to predict the vibration and noise radiation from cylindrical shells, with active stiffeners, into the surrounding fluid domain. The production cost as well as the life cycle and maintenance costs of the stiffened shells are computed using the Parametric Review of Information for Costing and Evaluation (PRICE) model. A Pareto/min-max multi-criteria optimization approach is then utilized to select the optimal locations and dimensions of the active stiffeners. Numerical examples are presented to compare the vibration and noise radiation characteristics of me optimally designed/controlled stiffened shells with the corresponding characteristics of plain un-stiffened and uncontrolled shells. The obtained results emphasize me importance of the adopted multi-criteria optimization approach in the design of quiet, low weight and low cost underwater shells which are suitable for various critical applications.
Analysis of Pump Induced Radiated Noise From Undersea Vehicles
Authors: Hassan Scott E. , Roberts Raymond W.
Published: November 2020

Positive displacement pumps are one of the many potential noise and vibration sources associated with undersea vehicles. This paper presents an approach to predict the tonals radiated from vane-type pumps mounted in undersea vehicles. The approach is based on using a numerical model of a vane pump coupled to an analytical model of the pump inlet hose and a finite element model of the hull and internal structure associated with the fluid-loaded undersea vehicle. An illustrative example is presented that demonstrates the influence of the various propagation paths and pump parameters on the overall radiated power. The basic approach can be readily extended and implemented as part of a simulation based design process for managing vehicle acoustics and vibration.
The Effect of Hertzian, Bending and Shearing Stiffness on Noise and Vibration
Authors: Abdo Jamil , Farhang Kambiz , Mohsen Mousa
Published: November 2020

Since the apparent stiffness due to contact of one surface on another relates directly to the localized resonant frequencies, it is believed that accurate account of this property will lead to the fundamental understanding of causes of friction-induced vibration and noise. The mathematical model of contact is utilized to develop formulae for normal and tangential contact stiffness. The inclusion of a study in which the various modes of elastic deflections of an asperity are also considered, as well as their effects. The bending, shear and Hertz contact modes of elastic deflection are assumed to simultaneously occur for an asperity. Investigation of the combined effect of bending, shear and Hertzian contributions to the contact stiffness is indicating that the equivalent contact stiffness is best represented, among the three types of stiffness, by that due to Hertzian contact.
Simulating and Detecting a Vibration-Induced Failure in an Air-Handling Assembly
Authors: McGee C. Gavin , Adams Douglas E.
Published: November 2020

Excessive vibrations usually cause mechanical parts to fail. This paper describes a vibration-induced failure in an air handling assembly. Cyclic impacts between a valve and a set of powdered metal bushings cause the failure. A variety of signal processing techniques are used to analyze experimental response data from the failing part including standard spectral signature approaches (i.e. Fourier, cepstral) in addition to more advanced time-frequency analysis techniques (i.e. wavelet contour maps). The theory and application of each method is reviewed in the context of the specific failure mode under consideration. The paper demonstrates that where friction or impact related vibrations are present, structural dynamic “health” monitoring schemes can be used to track changes in operating response signatures and schedule condition-based maintenance or re-design.
Stability and Bifurcation for the Equispaced, Periodic Motion of a Horizontal Impact Damper
Authors: Luo Albert C. J.
Published: November 2020

Stability and bifurcation conditions for the asymmetric, periodic motion of a horizontal impact damper under a periodic excitation are developed through four mappings for two switch-planes relative to discontinuities. Period-doubling bifurcation for equispaced motion does not occur, but the asymmetric period-1 motions change to the asymmetric, period-2 ones through a period doubling bifurcation. A numerical prediction for equispaced to chaotic motions is completed. The numerical and analytical predictions of the periodic motion are in very good agreement. The asymmetric, periodic motions are also simulated.
Stability Analysis of a Free-Standing Block With Friction on a Moving Foundation
Authors: Sinopoli Anna , Ageno Alessio
Published: November 2020

The problem analyzed here concerns the dynamic response of a bidimensional polygonal rigid body simply supported on a harmonically moving rigid ground. The immediate scientific purpose of the paper is to obtain and analyze the dynamic response by using a variational formulation, recently proposed by one of the authors [1], where the dynamics is described as a differential inclusion. This formulation allows us to determine the instantaneous accelerations of the system by means of a mechanical model with friction and unilateral constraints, which does not reduce the degrees of freedom or impose an “a priori” choice of the mechanism activated during the motion. By treating the friction coefficient as a stability parameter, it has been possible to obtain different kind of responses, ranging from rocking to sliding-rocking, and compare them with those obtained in the literature. Sliding-rocking motions obtained so far have exhibited not only harmonic but also interesting and more complex behaviors with chaotic features.

The search for theoretical and numerical instruments able to identify and classify these more complex motions was first performed in the case of rocking, characterized by a smaller number of degrees of freedom. A technique was then implemented for calculating Lyapunov’s exponents also during the time intervals of the impacts. The introduction and evaluation of these exponents can also permit us to perform the stability analysis with respect to overturning, by limiting the analysis and evaluation to the first impact that the system undergoes by starting at rest: in fact, large values of Lyapunov’s exponents before the first impact are connected with overturning during the motion which follows. This circumstance can make it easier to carry out the stability analysis with respect to overturning, as a function of the amplitude and frequency of the excitation.
Bending Effects in the Frictional Energy Dissipation in Lap Joints
Authors: Heinstein Martin W. , Segalman Daniel J.
Published: November 2020

Frictional energy dissipation in joints is an issue of longstanding interest in the effort to predict damping of built up structures. Even obtaining a qualitative understanding of how energy dissipation depends on applied loads has not yet been accomplished. Goodman[1] postulated that in harmonic loading, the energy dissipation per cycle would go as the cube of the amplitude of loading. Though experiment does support a power-law relationship, the exponent tends to be lower than Goodman predicted. Recent calculations discussed here suggest that the cause of that deviation has to with reshaping of the contact patch over each loading period.
Moving Force Identification for Multi-Span Bridges by Using Acceleration Measurements
Authors: Au F. T. K. , Jiang R. J. , Cheung Y. K.
Published: November 2020

This paper reports some initial findings in the attempt to develop a robust method to identify more than one moving force on multi-span non-uniform continuous bridges. To keep the number of unknowns in the moving force identification problem to a minimum, the modified beam vibration functions are chosen as the assumed modes of a multi-span bridge. These modified beam vibration functions satisfy the zero deflection conditions at all the intermediate supports as well as the boundary conditions at the two ends of the bridge. The least squares method is used to solve the inverse problem to get the closest approximation to the moving forces. The pseudo-inverse to obtain the solution to the inverse problem is obtained by singular value decomposition. Only acceleration measurements are used for the moving force identification. The results show that this method is applicable and robust.
Analysis of Varying Natural Frequencies and Damping Ratios of a Sample Parallel Manipulator Throughout its Workspace Using Linearized Equations of Motion
Authors: Kozak Kris , Ebert-Uphoff Imme , Singhose William
Published: November 2020

This article investigates the dynamic properties of robotic manipulators of parallel architecture. In particular, the dependency of the dynamic equations on the manipulator’s configuration within the workspace is analyzed. The proposed approach is to linearize the dynamic equations locally throughout the workspace and to plot the corresponding natural frequencies and damping ratios. While the results are only applicable for small velocities of the manipulator, they present a first step towards the classification of the nonlinear dynamics of parallel manipulators.

The method is applied to a sample manipulator with two degrees-of-freedom. The corresponding numerical results demonstrate the extreme variation of its natural frequencies and damping ratios throughout the workspace.
A Structural Health Monitoring System for Laminated Composites
Authors: Díaz Valdés Sergio H. , Soutis Costas
Published: November 2020

This investigation examines the application of low frequency Lamb waves for the detection of delaminations in thick composite laminates. Surface mounted piezoelectric devices were excited with a tone burst of few cycles generating a stress wave that propagates along the structure. Experiments were carried out on composite beam specimens where wave propagation distances over 2 m were achieved and artificially induced delaminations as small as 1 cm2 were successfully identified. The resonance spectrum method, which is based on the study of spectra obtained by forced mechanical resonance of samples using sine-sweep excitation, was used for measuring the A0 Lamb mode phase velocity. Finite element analyses of wave generation and propagation in wide laminated plates are also presented. The feasibility of employing piezoelectric devices for the development of smart structures, where a small and lightweight transducer system design is required, has been demonstrated.
Vibration Testing and Control of Inflatable Structures Using Smart Materials
Authors: Park Gyuhae , Kim Myung-Hyun , Mandin Matthias , Inman Daniel J.
Published: November 2020

An experimental investigation of vibration testing and control of an inflated thin-film torus is presented. Lightweight inflatable structures are a viable alternative in aerospace structure design. These structures, however, pose special problems in testing and in controlling vibrations due to their extremely lightweight, flexible, and high-damping properties.

In this study, we show that smart materials, which can be fully integrated into an inflatable space system, could be used as sensors/actuators in order to find modal parameters and to reduce vibrations. The results indicate the potential smart materials for use in the dynamics and control of inflated structures.
Evaluation of a Distributed Sensor for Structural Health Monitoring
Authors: Sundaresan M. J. , Ghoshal A. , Martin W. N. , Schulz M. J.
Published: November 2020

A distributed in-situ sensor that can simplify structural health monitoring is investigated in this paper. The distributed sensor can detect damage within the coverage area of the sensor by measuring acoustic emissions, but it cannot exactly locate the damage source due to the continuous nature of the sensor. A simulation and experiment showed that acoustic emissions occurring at any location on a composite panel can be detected by a single channel distributed sensor. In contrast, nine individual piezoceramic patch sensors would be needed to detect the acoustic emission.
Spatially Distributed Signals of Nonlinear Paraboloidal Shells With Distributed Neurons
Authors: Tzou H. S. , Ding J. H.
Published: November 2020

Effective health monitoring and distributed control of advanced structures depends on accurate measurements of dynamic responses of elastic structures. Conventional sensors used for structural measurement are usually add-on “discrete” devices. Lightweight distributed thin-film piezoelectric neurons fully integrated (laminated or embedded) with structural components can serve as in-situ sensors monitoring structure’s dynamic state and health status. This study is to investigate modal voltages and detailed signal contributions of linear or nonlinear paraboloidal shells of revolution laminated with piezoelectric neurons. Signal generation of distributed neuron sensors laminated on paraboloidal shells is defined first, based on the open-voltage assumption and Maxwell’s principle. The neuron signal of a linear paraboloidal shell is composed of a linear membrane component and a linear bending component; the signal of a nonlinear paraboloidal shell governed by the von Karman geometric nonlinearity is composed of nonlinear and linear membrane components and a linear bending component. Signal components and distributed modal voltages of linear and nonlinear paraboloidal shells with various curvatures and thickness are investigated.
Analysis of Belt-Drive Mechanics Using a Creep-Rate Dependent Friction Law
Authors: Leamy Michael J. , Wasfy Tamer M.
Published: November 2020

An analysis of the frictional mechanics of a steadily rotating belt-drive is carried out using a physically-appropriate creep-rate dependent friction law. Unlike in belt-drive mechanics analyzed using a Coulomb friction law, the current analysis predicts no adhesion zones in the belt-pulley contact region, although all response quantities (including the belt creep) approach those of the Coulomb law for a steep enough creep-rate law. Depending on the slope of the profile, one or two sliding zones exist on each pulley, which together, span the belt-pulley contact region. Closed-form expressions are obtained for the tension distribution, the sliding-zone are magnitudes, and the frictional and normal forces exerted on the belt. A sample two-pulley belt-drive is analyzed further to determine its pulley angular velocity ratio and belt-span tensions. Results from this analysis are compared to a dynamic finite element solution of the same belt-drive. Excellent agreement in predicted results is found. Due to the presence of arbitrarily large system rotations and a numerically-friendly friction law, the analytical solution presented herein is recommended as a convenient comparison test case for validating friction-enabled dynamic finite element schemes.
Nonlinearly Coupled in-Plane and Transverse Vibrations of a Spinning Disk
Authors: Baddour Natalie , Zu Jean W.
Published: November 2020

Previous nonlinear spinning disk models neglected the in-plane inertia of the disk since this permits the use of a stress function. This paper aims to consider the effect of including the in-plane inertia of the disk on the resulting nonlinear dynamics. The inclusion of the in-plane inertia results in coupling between the in-plane and transverse vibrations of the spinning disk. The full nonlinear equations are simplified to a simpler nonlinear two degrees-of-freedom model via the method of Galerkin. This 2 DOF model is analyzed with a canonical perturbation approach and with numerical simulations. Through the use of these analytical and numerical tools, it becomes apparent that the inclusion of in-plane inertia gives rise to new phenomena in the dynamics of the system that are not predicted if the in-plane inertia is ignored.
An Investigation of Torsional Wave Control in a Multiple Stepped Turbogenerator Shaft System
Authors: Hao Zhiyong , Ye Min , Fu Luhua
Published: November 2020

In the paper, a new analysis method is presented for calculating the torsional wave in a multi-stepped shaft system according to the elastic wave theory, and it is used to simulate the torsional vibration of a turbo-generator shaft system (TSS). Based on the continuous mass model, an active control strategy for minimizing the total energy of torsional vibration in a TSS is deduced against the excitation due to short circuits in the generator or ground faults in the electric network. The responses of torsional vibration and their control process are simulated under the different operate condition. It is shown that active control can not only achieve good vibration attenuation and a fast response to the faults, but also adapt the change of exciting load and work effectively in all of the operating range of the machine.
An Experimental Study of Torsional Vibration Absorbers
Authors: Haddow Alan G. , Shaw Steven W.
Published: November 2020

This paper presents results from tests completed on a rotor system fitted with pendulum-type torsional vibration absorbers. A review of the associated theoretical background is also given and the experimental and theoretical results are compared and contrasted. An overview of the test apparatus is provided and its unique features are discussed. To the best knowledge of the authors, this is the first time that a systematic study of the dynamic behavior of torsional vibration absorbers has been undertaken in a controlled environment.
Phase Shift Near Natural Frequencies of Non Linear Rods
Authors: Georgiou Ioannis T.
Published: November 2020

We study the transient and steady state dynamics of a special class of motions of forced planar rods with exact geometric nonlinearity. The attractors of these motions are separated by a finite jump at a critical forcing frequency in an attractor diagram of the undistorted configuration generated by a quasi-static frequency sweep at fixed forcing amplitude. As the frequency of the forcing passes through this critical or jump frequency, the motion (trajectory) of the undistorted configuration changes basin of attraction. For forcing frequency slightly greater than the jump frequency, the response trajectories of the undistorted configuration pass near an unstable periodic attractor and undergo continuous phase shift while approaching a stable attractor. For forcing frequency slightly smaller than the jump frequency, the response trajectories of the undistorted configuration pass near the same unstable attractor and undergo no net phase angle when landing on the stable attractor that attracts them. The phase-shifting property reveals that the frequncy at which the jump occurs is indeed a natural frequncy of the nonlinear rod.
Global Behavior of a Nonlinear Quasiperiodic Mathieu Equation
Authors: Zounes Randolph S. , Rand Richard H.
Published: November 2020

We investigate the interaction of subharmonic resonances in the nonlinear quasiperiodic Mathieu equation,(1)x..+[δ+ϵ(cos⁡ω1t+cos⁡ω2t)]x+αx3=0. We assume that ϵ ≪ 1 and that the coefficient of the nonlinear term, α, is positive but not necessarily small.

We utilize Lie transform perturbation theory with elliptic functions — rather than the usual trigonometric functions — to study subharmonic resonances associated with orbits in 2m : 1 resonance with a respective driver. In particular, we derive analytic expressions that place conditions on (δ, ϵ, ω1, ω2) at which subharmonic resonance bands in a Poincaré section of action space begin to overlap. These results are used in combination with Chirikov’s overlap criterion to obtain an overview of the O(ϵ) global behavior of equation (1) as a function of δ and ω2 with ω1, α, and ϵ fixed.
Signatures of Acoustic Emission Signals Generated During High Speed Cutting
Authors: Sitz Andre , Schwarz Udo , Kurths J. , Maus Doris , Wiese Michael , Warnecke G.
Published: November 2020

Acoustic emission signals generated during high speed cutting of steel are investigated. The data are represented in time-folded form. Several methods from linear and nonlinear data analysis based on time- and frequency-domain are applied to the data and reveal signatures of the observed acoustic emission signal. These investigations are first steps for modeling the cutting process by means of differential equations.
Linear and Nonlinear Dynamical Coupling of a Class of Electro-Mechanical Systems
Authors: Vidoli Stefano , Vestroni Fabrizio
Published: November 2020

The linear and nonlinear dynamics of an electro-mechanical system, characterized by a gyroscopic internal coupling, are analyzed. Since the technical importance of this system lies in the possibility of damping and controlling structural vibrations, the interest is focused on the energy exchanges between the mechanical and electric components. In order to maximize these energy transformations, the optimal values of the system parameters and their modifications in the nonlinear case are investigated.
Bifurcations and Chaos in Forced, Coupled Pendula
Authors: Yagasaki Kazuyuki
Published: November 2020

We consider forced, coupled pendula and show that they exhibit very complicated dynamics using the averaging method and Melnikov-type techniques. First, the averaged system for small oscillations of the pendula near the hanging state is analyzed. Codimension-one and -two local bifurcations at which several non-synchronized periodic orbits and quasiperiodic orbits are born in the original system are detected. The validity of the theoretical results is demonstrated by comparison with direct numerical integration results. Moreover, chaotic motions, which result from the Shilnikov type phenomena in the averaged systems, are observed in numerical simulations. Second, the second-order averaging method is applied to small perturbations of rotary orbits with no damping and external forcing. Analyzing the averaged system, we can describe nonlinear behavior in the original system. Finally, using a generalization of Melnikov method, we prove the occurrence of many other homo-clinic phenomena, which also yield chaotic dynamics.
Nonlinear Design-for-Control: Deploying Nonlinearity for Useful Purposes
Authors: Adams Douglas E.
Published: November 2020

Nonlinearity can be beneficial. It can enhance/degrade system performance, strengthen/weaken linear systems, and give rise to extraordinarily constructive/destructive behaviors. In spite of these potential benefits, engineers have historically neglected and/or removed nonlinearity when designing, analyzing, and controlling mechanical systems for good reason. This paper examines the notion of nonlinear mechanical design-for-control in the context of common applications where nonlinearity enhances performance in some way. Examples of how general nonlinear characteristics and specific nonlinear behaviors have been used in engineering applications are given. A framework for carrying out design optimization with reconfigurable nonlinear mechanical feedback loops is also discussed.
An Experimental Study for Collision Stimulus Device Using a Magneto-Spring
Authors: Fujita Etsunori , Nakagawa Noritoshi , Soga Norio , Ogura Yumi , Sugimoto Eiji , Kojima Shigeyuki
Published: November 2020

An experimental device that utilizes a magneto-spring and collision forces for a single-degree-of-freedom stimulus is proposed. By way of an actuator, the experimental device that was created in order to test the response created by a magneto-spring stimulus force arising from an impact force, applies a displacement stimulus to the magnet on one side, changing the distance between the magnets as well as the faced surface area of the magnets. The moving mass that, which supports the loaded mass and the magnet on other side, provides kinetic energy via the actuator and the magneto-spring. When the moving mass impact on impact plate, the impact plate turn over the motion of direction. This collision stimulus device is composed of a mechanisms having low damping, and being vibration device using a magneto-spring, it was verified through analysis and experimental studies to be a highly efficient shaker mechanism. In addition, when the stimulus energy from the shock vibration experiment is low, due to loaded mass move a quasi-zero spring constant or a low magnetic field gradient, it is thought that by generating anti-phase and a large relative displacement from a low frequency, a highly efficient shock stimulus mechanism can be achieved, even by applying the momentary impulse input as a disturbance, the magneto-spring, constant of non-linear characteristics and strong spring constant, elastic energy is used to create a symmetrical triangular shock wave.

On one hand, the relation between the inputs and outputs that use variations in the magnetostatic energy created by changes in the distance between the repulsed magnets and the faced surface area was verified by studying the amount of work created by the magneto-spring stimulus energy of a repulsed magnet system during one vibration cycle of the moving mass attached to a moving magnet and a fixed magnet. It is seen that the input/output energy characteristics of the magneto-spring stimulus force are a highly efficient mechanism due to mageto-spring move in a strong magnetic field gradient. However, it is seen that mechanical amplification mechanism that utilizes a magneto-spring and collision forces are a highly efficient mechanism due to mageto-spring move in a low magnetic field gradient. The collision stimulus device using a quasi-zero spring constant and a elastic energy of magneto-spring changes sinusoidal wave, that vibration device applies, into a symmetrical triangular shock wave found in a large collision force and amplified amplitude, due to external disturbance which acts as a trigger, a elastic energy of magneto-spring and distance between impact plates optimized. However, it was realized that when a force greater than the prescribed amount is applied as resistance. As a results, the vibration energy is diminished, a shock wave change a symmetrical sinusoidal wave due to loaded mass move in a low magnetic field gradient or a quasi-zero spring constant.
A Study on the Characteristics of Rubber Flexible Pipes
Authors: Zhao Yin-Long , He Lin , Qian Wei-Jian , Zhu Shi-Jian
Published: November 2020

This paper studies the static and dynamic properties of the rubber flexible pipes. The theoretical formula for calculating the strength of the rubber flexible pipes is given. A mathematical model for predicting the dynamic characteristics of the viscoelastic pipe wall pipeline is setup. Finally, the model is solved analytically.
Active Stabilization of Centrifugal Compressor Using Adjustable Geometry Impeller
Authors: Eldin K. M. Saad
Published: November 2020

Recent work has shown that variable impeller geometry of the centrifugal compression system can be actively stabilized against the instability known as surge, thereby realizing a significant gain in system mass flow rate. In this context, the paper presents an experimental study about the influence of the impeller blade configuration on the extension of the stabilized characteristic margin beyond the natural surge line and enlarge the usable compressor operating region. This method is estimated from the two major control methods which: surge avoidance control and surge suppression control. The impeller of tandem type with zero overlap is found to be a good sample to satisfy the above concept. The impeller is working as full bladed at stable regime, but it could be transferred into tandem bladed when the mass flow rate decreases below a certain minimum value, just before rotating stall occurs. The operating point moves downwards to another characteristic curve belonging to the new configuration, which has a surge margin less than the original one by 56 percent, at high speed.

Herein the effect of tandem shift angle on extending the stabilized range is studied experimentally and a control criterion is suggested. The pressure ratio at the new characteristic curve is decreased by about 3 percent and maximum efficiency is decreased also by about 28 percent.
Wavelet Based Demodulation of Vibration Signals Generated by Defects in Rolling Element Bearings
Authors: Yiakopoulos Christos T. , Antoniadis Ioannis A.
Published: November 2020

Envelope detection or demodulation methods for bearing vibration response signals have been established as a dominant analysis method for bearing fault diagnosis, since they can separate the useful part of the signal from its redundant contents. A new effective demodulation method is proposed, based on the Discrete Wavelet Transform (DWT). The method fully exploits the underlying physical concepts of the modulation mechanism, present in the vibration response of faulty bearings, using the excellent time-frequency localization properties of the wavelet analysis. Two key elements, resulting to the successful implementation of the method, are its practical independence from the choice of the specific wavelet family to be used and the limited number of the wavelet levels, that are required for its practical application. Experimental results and industrial measurements for three different types of bearing faults, confirm the validity of the overall approach.
Active Control for a 2DOF of Building Including Elastoplastic Soil-Structure Coupling Terms
Authors: Lamarque C.-H. , Kacprzak Grzegorz , Awrejcewicz Jan
Published: November 2020

An active control procedure has been applied to a two degrees-of-freedom mechanical system including the elastoplastic terms. The theoretical consideration resulted in a solution to the classical Riccati equations which holds for both stationary and non-stationary cases. The included numerical example demonstrates an efficiency of the introduced theory and the numerical scheme in order to an active control of building-soil-foundation model.
Efficacy of Integrating Cervical Posture Correction With Lumbar Stabilization Exercises for Mechanical Low Back Pain: A Randomized Blinded Clinical Trial
Authors: Elabd Aliaa M. , Rasslan Salah-Eldin B. , Elhafez Haytham M , Elabd Omar M. , Behiry Mohamed A. , Elerian Ahmed I.
Published: November 2020

Although current lumbar stabilization exercises are beneficial for chronic mechanical low back pain, further research is recommended focusing on global spinal alignment normalization. This randomized, controlled, blinded trial was conducted to determine the effects of adding cervical posture correction to lumber stabilization on chronic mechanical low back pain. Fifty adult patients (24 males) with chronic mechanical low back pain and forward head posture received 12 weeks treatment of either both programs (group A) or lumbar stabilization (group B). The primary outcome was back pain. The secondary outcomes included the craniovertebral angle, Oswestry Disability Index, C7-S1 sagittal vertical axis, and sagittal intervertebral movements. The multivariate analysis of variance indicated a significant group-by-time interaction (P = .001, partial η2 = .609). Pain, disability, C7-S1 sagittal vertical axis, and l2-l3 intervertebral rotation were reduced in group A more than B (P = .008, .001, .025, and .001). Craniovertebral angle was increased in A when compared to B (P = .001). However, there were no significant group-by-time interactions for other intervertebral movements. Within-group comparisons were significant for all outcomes except for craniovertebral angle within patients in the control group. Adding cervical posture correction with lumber stabilization for management of chronic low back pain seemed to have better effects than the application of a stabilization program only.
How Do Profiles of Need-Supportive and Controlling Coaching Relate to Team Athletes’ Motivational Outcomes? A Person-Centered Approach
Authors: Reynders Bart , Van Puyenbroeck Stef , Ceulemans Eva , Vansteenkiste Maarten , Vande Broek Gert
Published: November 2020

Building on recent self-determination theory research differentiating controlling coaching into a demanding and domineering approach, this study examined the role of both approaches in athletes’ motivational outcomes when accompanied by autonomy support or structure. Within team-sport athletes (N = 317; mean age = 17.67), four sets of k-means cluster analyses systematically pointed toward a four-cluster solution (e.g., high–high, high–low, low–high, and low–low), regardless of the pair of coaching dimensions used. One of the identified coaching profiles involved coaches who are perceived to combine need-supportive and controlling behaviors (i.e., high–high). Whereas combining need-supportive and domineering behaviors (i.e., high–high) yields lower autonomous motivation and engagement compared with a high need-support profile (i.e., high–low), this is less the case for the combination of need-supportive and demanding behaviors (i.e., high–high). This person-centered approach provides deeper insights into how coaches combine different styles and how some forms of controlling coaching yield a greater cost than others.
EGF promotes
DKK1
transcription in hepatocellular carcinoma by enhancing the phosphorylation and acetylation of histone H3
Authors: Niu Jie , Li Wei , Liang Chao , Wang Xiao , Yao Xin , Yang Ruo-Han , Zhang Zhan-Sheng , Liu Han-Fang , Liu Fan-Ye , Pei Shu-Hua , Li Wen-Qi , Sun Hua , Fang Dong , Xie Song-Qiang
Published: November 2020

Growth factor–induced parallel pathways stimulate
DKK1
expression and metastasis in liver cancer.
Engineered chemotaxis core signaling units indicate a constrained kinase-off state
Authors: Muok Alise R. , Chua Teck Khiang , Srivastava Madhur , Yang Wen , Maschmann Zach , Borbat Petr P. , Chong Jenna , Zhang Sheng , Freed Jack H. , Briegel Ariane , Crane Brian R.
Published: November 2020

Bacterial chemoreceptors keep the kinase CheA inactive by locking down its catalytic core.
Recovery and Community Succession of theZostera marinaRhizobiome after Transplantation
Authors: Wang Lu , English Mary K. , Tomas Fiona , Mueller Ryan S.
Published: November 2020

Seagrasses are important coastal species that are declining globally, and transplantation can be used to combat these declines. However, the bacterial communities associated with seagrass rhizospheres and roots (the microbiome) are often disturbed or removed completely prior to transplantation.
Draft Genome Sequences of Vibrio cholerae Non-O1, Non-O139 Isolates from Common Tern Chicks (
Sterna hirundo
) following a Mass Mortality Event
Authors: Strauch Eckhard , Jäckel Claudia , Hammerl Jens Andre , Hennig Veit , Roschanski Nicole , Dammann Insa
Published: November 2020

Vibrio cholerae
is an inhabitant of aquatic environments worldwide. Here, we report the draft genome sequences of eight
V. cholera
non-O1, non-O139 isolates that were recovered from the corpses of two seabird chicks (common terns) following a mass mortality event in a German breeding colony in 2019.
Supplemental Material: Tectonic and magmatic evolution of the Aqishan-Yamansu belt: A Paleozoic arc-related basin in the Eastern Tianshan (NW China)
Authors: Zhang Shuanliang , Chen Huayong , al. et
Published: November 2020

Cathodoluminescence images for zircons, geochemical and geochronology results, summary of geochronology and geochemistry data for the magmatism in the studied areas.
Accuracy of the Edinburgh Postnatal Depression Scale (EPDS) for screening to detect major depression among pregnant and postpartum women: systematic review and meta-analysis of individual participant data
Authors: Levis Brooke , Negeri Zelalem , Sun Ying , Benedetti Andrea , Thombs Brett D
Published: November 2020

Objective

To evaluate the Edinburgh Postnatal Depression Scale (EPDS) for screening to detect major depression in pregnant and postpartum women.

Design

Individual participant data meta-analysis.

Data sources

Medline, Medline In-Process and Other Non-Indexed Citations, PsycINFO, and Web of Science (from inception to 3 October 2018).

Eligibility criteria for selecting studies

Eligible datasets included EPDS scores and major depression classification based on validated diagnostic interviews. Bivariate random effects meta-analysis was used to estimate EPDS sensitivity and specificity compared with semi-structured, fully structured (Mini International Neuropsychiatric Interview (MINI) excluded), and MINI diagnostic interviews separately using individual participant data. One stage meta-regression was used to examine accuracy by reference standard categories and participant characteristics.

Results

Individual participant data were obtained from 58 of 83 eligible studies (70%; 15 557 of 22 788 eligible participants (68%), 2069 with major depression). Combined sensitivity and specificity was maximised at a cut-off value of 11 or higher across reference standards. Among studies with a semi-structured interview (36 studies, 9066 participants, 1330 with major depression), sensitivity and specificity were 0.85 (95% confidence interval 0.79 to 0.90) and 0.84 (0.79 to 0.88) for a cut-off value of 10 or higher, 0.81 (0.75 to 0.87) and 0.88 (0.85 to 0.91) for a cut-off value of 11 or higher, and 0.66 (0.58 to 0.74) and 0.95 (0.92 to 0.96) for a cut-off value of 13 or higher, respectively. Accuracy was similar across reference standards and subgroups, including for pregnant and postpartum women.

Conclusions

An EPDS cut-off value of 11 or higher maximised combined sensitivity and specificity; a cut-off value of 13 or higher was less sensitive but more specific. To identify pregnant and postpartum women with higher symptom levels, a cut-off of 13 or higher could be used. Lower cut-off values could be used if the intention is to avoid false negatives and identify most patients who meet diagnostic criteria.

Registration

PROSPERO (CRD42015024785).
Socioeconomic deprivation and development of diabetic retinopathy in patients with type 1 diabetes mellitus
Authors: Alvarez-Ramos Pablo , Jimenez-Carmona Soledad , Alemany-Marquez Pedro , Cordoba-Doña Juan Antonio , Aguilar-Diosdado Manuel
Published: November 2020

Introduction

Very little is known about the influence of socioeconomic status on type 1 diabetes mellitus (T1DM) complications. Our aim was to determine whether socioeconomic level is a risk factor for the development of diabetic retinopathy (DR) in patients with T1DM.

Research design and methods

A cohort of 150 patients with T1DM were studied prospectively over 9 years. Socioeconomic status was assessed using a neighborhood-level measure based on an index of deprivation. The contribution of other variables such as hypertension, dyslipidemia, diabetic nephropathy and smoking habit was evaluated. Cox proportional hazards models were used to quantify the associations.

Results

The incidence of DR was 21.6 cases per 1000 patient-years. Multivariable analyses showed that for each percentage point increase in glycated hemoglobin (HbA1c), the risk of developing DR increased by 58% (HR 1.58, 95% CI 1.19 to 2.10).

Patients with T1DM onset >18 years of age and resident in areas of lower socioeconomic levels presented with almost triple the risk of developing DR (HR 2.95, 95% CI 1.08 to 8.00) compared with those with onset <18 years of age and resident in less deprived areas. We did not find significant relationships with other variables studied such as hypertension, dyslipidemia, diabetic nephropathy and smoking habit.

Conclusions

Low socioeconomic level is a risk factor, independent of glycemic control, in the development of DR in patients with T1DM when the onset of diabetes is in adulthood. This finding indicates that socioeconomic status and age of onset need to be considered in population screening for DR in patients with T1DM.
UK healthcare staff experiences and perceptions of a mass casualty terrorist incident response: a mixed-methods study
Authors: Skryabina Elena , Betts Naomi , Reedy Gabriel , Riley Paul , Amlôt Richard
Published: November 2020

Introduction

System learning from major incidents is a crucial element of improving preparedness for response to any future incidents. Sharing good practice and limitations stimulates further actions to improve preparedness and prevents duplicating mistakes.

Methods

This convergent parallel mixed methods study comprises data from responses to an online survey and individual interviews with healthcare staff who took part in the responses to three terrorist incidents in the UK in 2017 (Westminster Bridge attack, Manchester Arena Bombing and London Bridge attack) to understand limitations in the response and share good practices.

Results

The dedication of NHS staff, staff availability and effective team work were the most frequently mentioned enabling factors in the response. Effective coordination between teams and a functional major incident plan facilitated an effective response. Rapid access to blood products, by positioning the blood bank in the ED, treating children and parents together and sharing resources between trauma centres were recognised as very effective innovative practices. Recent health emergency preparedness exercises (HEPEs) were valued for preparing both Trusts and individual staff for the response. Challenges included communication between ambulance services and hospitals, difficulties with patient identification and tracking and managing the return to ‘normal’ work patterns post event. Lack of immediately available clinical protocols to deal with blast injuries was the most commonly mentioned clinical issue. The need for psychosocial support for responding and supporting staff was identified.

Discussion

Between-agencies communication and information sharing appear as the most common recurring problems in mass casualty incidents (MCIs). Recent HEPEs, which allowed teams, interdisciplinary groups, and different agencies to practice responding to similar simulated incidents, were important and informed actions during the real response. Immediate and delayed psychosocial support should be in place for healthcare staff responding to MCIs.
Endocrine therapy use and cardiovascular risk in postmenopausal breast cancer survivors
Authors: Matthews Anthony A , Peacock Hinton Sharon , Stanway Susannah , Lyon Alexander Richard , Smeeth Liam , Lund Jennifer L , Bhaskaran Krishnan
Published: November 2020

Objective

Examine the effect of tamoxifen and aromatase inhibitors (AIs) on the risk of 12 clinically relevant cardiovascular outcomes in postmenopausal female breast cancer survivors.

Methods

We carried out two prospective cohort studies among postmenopausal women with breast cancer in UK primary care and hospital data (2002–2016) and US Surveillance, Epidemiology and End Results-Medicare data (2008–2013). Using Cox adjusted proportional hazards models, we compared cardiovascular risks between AI and tamoxifen users; and in the USA, between users of both drug classes and women receiving no endocrine therapy.

Results

10 005 (UK) and 22 027 (USA) women with postmenopausal breast cancer were included. In both countries, there were higher coronary artery disease risks in AI compared with tamoxifen users (UK age-standardised incidence rate: 10.17 vs 7.51 per 1000 person-years, HR: 1.29, 95% CI 0.94 to 1.76; US age-standardised incidence rate: 36.82 vs 26.02 per 1000 person-years, HR: 1.29, 95% C I1.06 to 1.55). However, comparisons with those receiving no endocrine therapy (US data) showed no higher risk for either drug class and a lower risk in tamoxifen users (age-standardised incidence rate tamoxifen vs unexposed: 26.02 vs 35.19 per 1000 person-years, HR: 0.74, 95% 0.60 to 0.92; age-standardised incidence rate AI vs unexposed: 36.82 vs 35.19, HR: 0.96, 95% CI 0.83 to 1.10). Similar patterns were seen for other cardiovascular outcomes (arrhythmia, heart failure and valvular heart disease). As expected, there was more venous thromboembolism in tamoxifen compared with both AI users and those unexposed.

Conclusions

Higher risks of several cardiovascular outcomes among AI compared with tamoxifen users appeared to be driven by protective effects of tamoxifen, rather than cardiotoxic effects of AIs.
Long-term survival of patients with stage III colon cancer treated with VRP-CEA(6D), an alphavirus vector that increases the CD8+ effector memory T cell to Treg ratio
Authors: Crosby Erika J , Hobeika Amy C , Niedzwiecki Donna , Rushing Christel , Hsu David , Berglund Peter , Smith Jonathan , Osada Takuya , Gwin III William R , Hartman Zachary C , Morse Michael A , Lyerly Herbert Kim
Published: November 2020

Background

There remains a significant need to eliminate the risk of recurrence of resected cancers. Cancer vaccines are well tolerated and activate tumor-specific immune effectors and lead to long-term survival in some patients. We hypothesized that vaccination with alphaviral replicon particles encoding tumor associated antigens would generate clinically significant antitumor immunity to enable prolonged overall survival (OS) in patients with both metastatic and resected cancer.

Methods

OS was monitored for patients with stage IV cancer treated in a phase I study of virus-like replicon particle (VRP)-carcinoembryonic antigen (CEA), an alphaviral replicon particle encoding a modified CEA. An expansion cohort of patients (n=12) with resected stage III colorectal cancer who had completed their standard postoperative adjuvant chemotherapy was administered VRP-CEA every 3 weeks for a total of 4 immunizations. OS and relapse-free survival (RFS) were determined, as well as preimmunization and postimmunization cellular and humoral immunity.

Results

Among the patients with stage IV cancer, median follow-up was 10.9 years and 5-year survival was 17%, (95% CI 6% to 33%). Among the patients with stage III cancer, the 5-year RFS was 75%, (95%CI 40% to 91%); no deaths were observed. At a median follow-up of 5.8 years (range: 3.9–7.0 years) all patients were still alive. All patients demonstrated CEA-specific humoral immunity. Patients with stage III cancer had an increase in CD8 +TEM(in 10/12) and decrease in FOXP3 +Tregs (in 10/12) following vaccination. Further, CEA-specific, IFNγ-producing CD8+granzyme B+TCMcells were increased.

Conclusions

VRP-CEA induces antigen-specific effector T cells while decreasing Tregs, suggesting favorable immune modulation. Long-term survivors were identified in both cohorts, suggesting the OS may be prolonged.