bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the Suitability of Utilizing Permutation Entropy to Characterize Gait Dynamics
Authors: Leverick Graham , Szturm Tony , Wu Christine
Published: March 2014

Permutation entropy (PE) is a natural measure of the complexity of a dynamic system which boasts robustness to noise and computational efficiency. Since its introduction in 2002, PE has served as a valuable tool for assessing nonlinear systems such as speech signals and EEG signals. In this paper, the suitability of utilizing PE as a new method for characterizing walking gait dynamics is explored. Results obtained by analyzing the medial-lateral center of pressure migration of participants during treadmill walking demonstrate that PE shows good preliminary repeatability. PE shows sensitivity to a change in walking conditions; walk alone vs. addition of a concurrent cognitive task. A highly significant age effect in PE (p<0.001) during dual task walking was observed. Analysis revealed no significant age effect on PE for the walk alone condition.
Design of Automotive Control Systems Robust to Hardware Imprecision
Authors: Edelberg Kyle , Pan Selina , Hedrick J. Karl
Published: March 2014

The hardware used for software implementation on a physical system introduces uncertainty into the controller. If neglected during design, this uncertainty can lead to poor controller performance, resulting in significant design and verification iterations. In this work, the effect of sampling time, quantization, and fixed-point computation are directly accounted for in the control design. Sampling time is compensated for by a discrete-time controller. A generic methodology is developed for modeling the worst-case scenario effect of quantization and fixed-point computation on the control commands. The cold-start emission control problem is used as a case study, and a discrete-time sliding surface controller is developed. Verification is performed to ensure the estimated worst-case scenario uncertainty bounds are accurate. The bounds are incorporated into a modified version of the control laws. During simulation the modified controller demonstrates significant reduction in tracking error in the presence of hardware imprecisions.
Sliding Mode Coordination Control Design for Multiagent Systems
Authors: Ghasemi Masood , Nersesov Sergey G.
Published: March 2014

In this paper, we develop a coordination control technique for a group of agents described by a general class of underactuated dynamics. The objective is for the agents to reach and maintain a desired formation characterized by steady-state distances between the neighboring agents. We use graph theoretic notions to characterize communication topology in the network determined by the information flow directions and captured by the graph Laplacian matrix. Furthermore, using sliding mode control approach, we design decentralized controllers for individual agents that use only data from the neighboring agents which directly communicate their state information to the current agent in order to drive the current agent to the desired steady state. Finally, we show the efficacy of our theoretical results on the example of a system of wheeled mobile robots that reach and maintain the desired formation.
Defect Growth Prediction in Rolling Bearings Based on Approximate Entropy
Authors: Wang Peng , Gao Robert X. , Wang Huaqing , Yuan Hongfang
Published: March 2014

By quantifying the regularity vibration signals measured on rolling bearings, Approximate Entropy (ApEn) provides an effective measure for characterizing the structural degradation of bearings, and the severity of the defect. This paper investigates the relationship between ApEn and different failure modes of bearings. It is shown that. ApEn values decrease with the degradation of bearing defects. After introducing the theoretical background, experimental analysis are presented to quantify variation of ApEn values as a measure for defect mode and severity. A life cycle experiment is introduced to evaluate a defect growth precondition model based on regression analysis and Genetic Algorithm. Results show that ApEn is effective for bearing defect diagnosis and remaining service life prognosis.
Robot Guided Sheaths (RoGS) for Percutaneous Access to the Pediatric Kidney: Patient-Specific Design and Preliminary Results
Authors: Morimoto Tania K. , Hsieh Michael H. , Okamura Allison M.
Published: March 2014

Robot-guided sheaths consisting of pre-curved tubes and steerable needles are proposed to provide surgical access to locations deep within the body. In comparison to current minimally invasive surgical robotic instruments, these sheaths are thinner, can move along more highly curved paths, and are potentially less expensive. This paper presents the patient-specific design of the pre-curved tube portion of a robot-guided sheath for access to a kidney stone; such a device could be used for delivery of an endoscope to fragment and remove the stone in a pediatric patient. First, feasible two-dimensional paths were determined considering workspace limitations, including avoidance of the ribs and lung, and minimizing collateral damage to surrounding tissue by leveraging the curvatures of the sheaths. Second, building on prior work in concentric-tube robot mechanics, the mechanical interaction of a two-element sheath was modeled and the resulting kinematics was demonstrated to achieve a feasible path in simulation. In addition, as a first step toward three-dimensional planning, patient-specific CT data was used to reconstruct a three-dimensional model of the area of interest.
Hybrid Powertrain Optimization With Real-Time Traffic Information
Authors: Mohd Zulkefli Mohd Azrin , Zheng Jianfeng , Sun Zongxuan , Liu Henry
Published: March 2014

Combining hybrid powertrain optimization with traffic information has been researched before, but tradeoffs between optimality, driving-cycle sensitivity and speed of calculation have not been cohesively addressed. Optimizing hybrid powertrain with traffic can be done through iterative methods such as Dynamic Programming (DP), Stochastic-DP and Model Predictive Control, but high computation load limits their online implementation. Equivalent Consumption Minimization Strategy (ECMS) and Adaptive-ECMS were proposed to minimize computation time, but unable to ensure real-time charge-sustaining-operation (CS) in transient traffic environment. Others show relationship between Pontryagin’s Minimum Principles (PMP) and ECMS, but iteratively solve the CS-operation problem offline. This paper proposes combining PMP’s necessary conditions for optimality, with sum-of State-Of-Charge-derivative for CS-operation. A lookup table is generated offline to interpolate linear mass-fuel-rate vs net-power-to-battery slopes to calculate the equivalence ratio for real-time implementation with predicted traffic data. Maximum fuel economy improvements of 7.2% over Rule-Based is achieved within a simulated traffic network.
Estimating the Concentration Imbalance of a Vanadium Redox Flow Battery With Crossover Using a Constrained Extended Kalman Filter
Authors: Yu Victor , Chen Dongmei
Published: March 2014

One of the main issues with vanadium redox flow batteries is that vanadium ions travels across the membrane during operation which leads to a concentration imbalance and capacity loss after long-term cycling. Precise state of charge (SOC) monitoring allows the operator to effectively schedule electrolyte rebalancing and devise a control strategy to keep the battery running under optimal conditions. However, current SOC monitoring methods are too expensive and impractical to implement on commercial VRFB systems. Furthermore, physical models alone are neither reliable nor accurate enough to predict long-term capacity loss. In this paper, we present an application of using an extended Kalman filter (EKF) to estimate the total vanadium concentration in each half-cell by combining three voltage measurements and a state prediction model without crossover effects. Simulation results show that the EKF can accurately predict capacity loss for different crossover patterns over a few hundred cycles.
Development of a Master-Slave Robotic System for MRI-Guided Intracardiac Interventions
Authors: Salimi Amirhossein , Ramezanifar Amin , Mohammadpour Javad , Grogoriadis Karolos M.
Published: March 2014

Restricted space inside the magnetic resonance imaging (MRI) scanner bore prevents surgeons to directly interact with the patient during MRI-guided procedures. This motivates the development of a robotic system that can act as an interface during those interventions. In this paper, we present a master-slave robotic system as a solution to the aforedescribed issue. The proposed system consists of a commercial PHANTOM device (product of The Sensable Technologies) as the master robot and an MRI-compatible patient-mounted parallel platform (that we name ROBOCATH) designed to serve as the slave mechanism inside the scanner bore. We present in this paper the design principles for the platform, as well as the PID control design for the system. We use our experimental setup to evaluate the performance of the system by examining the effectiveness of the slave platform in tracking the reference trajectories generated by the master robot.
Investigation on the Energy Management Strategy for Hydraulic Hybrid Wheel Loaders
Authors: Wang Feng , Mohd Zulkefli Mohd Azrin , Sun Zongxuan , Stelson Kim A.
Published: March 2014

Energy management strategies for a hydraulic hybrid wheel loader are studied in this paper. The architecture of the hydraulic hybrid wheel loader is first presented and the differences of the powertrain and the energy management system between on-road vehicles and wheel loaders are identified. Unlike the on-road vehicles where the engine only powers the drivetrain, the engine in a wheel loader powers both the drivetrain and the working hydraulic system. In a non-hybrid wheel loader, the two sub-systems interfere with each other since they share the same engine shaft. By using a power split drivetrain, it not only allows for optimal engine operation and regenerative braking, but also eliminates interferences between driving and working functions, which improve the productivity, fuel efficiency and operability of the wheel loader. An energy management strategy (EMS) based on dynamic programming (DP) is designed to optimize the operation of both the power split drivetrain and the working hydraulic system. A short loading cycle is selected as the duty cycle. The EMS based on DP is compared with a rule-based strategy through simulation.
A Comparison of the Simulated Dynamics of Various Models Used to Predict Undeformed Chip Thickness in High-Speed Low-Radial-Immersion Milling Processes
Authors: Bryan Josiah A. , Fales Roger C.
Published: March 2014

Various models have been proposed to estimate the undeformed thickness of chips produced by a CNC milling tool, in order to calculate the forces acting on the tool. The choice of model significantly affects the simulated dynamics of the tool, thereby affecting the dynamic stability of the simulated process and whether or not chatter occurs in a given cutting scenario. Simulations of the dynamics of the milling process can be used to determine the conditions at which chatter occurs, which can lead to poor surface finish and tool damage. The dynamics of a traditional model and a more detailed numerical model are simulated here with particular emphasis on the differences in their chatter bifurcation points. High-speed, low-radial-immersion milling processes are simulated because of their application in industrial high-precision machining.
A Lumped-Parameter Model for Dynamic MR Damper Control
Authors: Case David , Taheri Behzad , Richer Edmond
Published: March 2014

The dynamic behavior of a small-scale magnetorheological damper intended for use in a tremor-suppression orthosis is characterized through experimental analysis and finite element simulation. The combined frequency response of both the electromagnetic coil and the fluid particles is modeled by a second-order transfer function. The output of this function is an effective current that, combined with piston velocity, is empirically related to resistance force of the damper. The derived model demonstrates high-fidelity to experimental testing of the damper under variable piston velocity and applied current within the expected frequency range of pathological tremor. The model is thus deemed suitable for use in a control algorithm for the mechanical suppression of tremor.
Backstepping-Based Hybrid Target Tracking Control for a Carangiform Robotic Fish
Authors: Chen Songlin , Wang Jianxun , Tan Xiaobo
Published: March 2014

In this paper we apply backstepping technique to develop a novel hybrid target-tracking control scheme for a carangiform robotic fish, based on a dynamic model that combines rigid-body dynamics with Lighthill’s large-amplitude elongated-body theory. This hybrid controller consists of an open-loop turning controller and a closed-loop approaching controller. A hysteretic switching strategy based on the orientation error is designed. Using Lyapunov analysis, we show that the trajectory of the robotic fish will converge to the target point. The effectiveness of the proposed control strategy is demonstrated through both simulations and experiments.
Enhanced Proportional-Derivative Control of a Micro Quadcopter
Authors: Johnson Norman L. , Leang Kam K.
Published: March 2014

This paper studies the design of an enhanced proportional-derivative (PD) controller to improve the transient response of a micro quadrotor helicopter (quadcopter). In particular, the controller minimizes the effect of disturbances by considering the orientation and rotation of the platform. A dynamics model is developed for an experimental micro quadcopter platform, and simulation results are presented that compare the proposed enhanced PD controller to a standard PD controller. Results show a 50% reduction in the peak response and a 45% reduction in the settling time, demonstrating the effectiveness of the controller.
Decentralized Control of Print Registration in Roll-to-Roll Printing Presses
Authors: Seshadri Aravind , Pagilla Prabhakar R.
Published: March 2014

Roll-to-roll (R2R) manufacturing is a type of continuous manufacturing process extensively used to produce a wide variety of consumer products, such as plastics, paper, films, non-wovens, textile, etc. Recent advances in nanotechnology and material science have enabled the possibility of manufacturing electronics on a flexible substrate using R2R printing techniques. Even though the feasibility of printing electronics on flexible substrates has been extensively studied, continuous printing on a moving substrate using R2R techniques has not been adequately investigated. To facilitate progress towards high precision R2R printing, a systematic investigation of the various aspects that affect print quality and ways in which those can be influenced by different control configurations facilitated by choice and location of various components of the print section is necessary.

In this paper we investigate two common control configurations for R2R printing based on the structure of the R2R print section and various components available for control. For these two configurations we develop a state-space model that contains both state and input delays. We propose a decentralized, memoryless, state feedback control law for both control configurations and show the stability of the closed loop systems using frequency domain delay-dependent stability conditions. These control configurations are evaluated and compared using model simulations and discussions on the effectiveness of each strategy are provided.
Control of a Nonlinear Pressure-Regulating Engine Bleed Valve in Aircraft Air Management Systems
Authors: Cooper John R. , Cao Chengyu , Tang Jiong
Published: March 2014

This paper presents an adaptive control algorithm, based on the ℒ 1 adaptive control method, for controlling the pressure of engine bleed air in a commercial aircraft. The pressure is affected by a control valve that is part of a larger air management system which includes control valves for temperature and flow rate as well as a heat exchanger or precooler. A system model is presented including valve hysteresis due to backlash and dry friction. Simulations are conducted for a control valve subject to unmeasured disturbance, and the adaptive control results are compared to those of a traditional proportional-integral controller.
Active Vibration Control Based on Self-Sensing for Unknown Target Structures by Direct Velocity Feedback With Adaptive Feed-Forward Cancellation
Authors: Yabui Shota , Kajiwara Itsuro , Okita Ryohei
Published: March 2014

This paper presents active vibration control based on self-sensing for unknown target structures by direct velocity feedback (DVFB) with enhanced adaptive feed-forward cancellation (AFC). AFC is known as an adaptive control method, and the adaptive algorithm can estimate a periodic disturbance. In a previous study, an enhanced AFC was developed to compensate for a non-periodic disturbance. An active vibration control based on self-sensing by DVFB can suppress mechanical resonance by using relative velocity between the voice coil actuator and a target structure. In this study, the enhanced AFC was applied to compensate disturbance for the self-sensing vibration control system. The simulation results showed the vibration control system with DVFB and enhanced AFC could suppress mechanical resonance and compensate disturbances.
Gliding Robotic Fish and its Tail-Enabled Yaw Motion Stabilization Using Sliding Mode Control
Authors: Zhang Feitian , Tan Xiaobo
Published: March 2014

Gliding robotic fish is a new type of underwater robots that combines the energy-efficiency of underwater gliders and the high maneuverability of robotic fish. The tail fin of a gliding robotic fish provides the robot more control authority, especially for the lateral motion, compared with traditional underwater gliders. In this paper, the design and development of a gliding robotic fish prototype is first presented, followed by its dynamic model. We then focus on the problem of tail-enabled yaw stabilization during gliding, where a sliding mode controller is proposed. Both simulation and experimental results are demonstrated to validate the effectiveness of the proposed controller.
Graph Laplacian Design for Fast Consensus of a LTI System With Heterogeneous Agent Couplings and Homogeneous Inter-Agent Delays
Authors: Qiao Wei , Atay Fatihcan M. , Sipahi Rifat
Published: March 2014

A class of LTI consensus network dynamics with heterogeneous agent coupling strengths and homogeneous inter-agent delays is under investigation. An approach to design the graph Laplacian of the system is developed here for achieving fast consensus, departing from the analytical study of the rightmost eigenvalue behavior of this dynamics. Detailed design procedure is presented with a demonstrative example.
Modeling and Control of a Thermoelastic Beam
Authors: Tuzcu Ilhan , Gonzalez-Rocha Javier
Published: March 2014

The objective of this paper is to model a thermoelastic beam and use thermoelectric heat actuators dispersed over the beam to control not only its vibration, but also its temperature. The model is represented by two coupled partial differential equations governing the elastic bending displacement and temperature variation over the length of the beam. The partial differential equations are replaced by a set of ordinary differential equations through discretization. The first-order ordinary differential equations are cast in the compact state-space form to be used in the thermoelastic analysis and control. The Linear Quadratic Gaussian (LQG) is used for control design. An numerical application to a uniform cantilever beam demonstrates the coupling between the temperature and the elastic displacement and feasibility of using thermoelectric actuators in controlling the vibration and temperature simultaneously.
Online Simultaneous State Estimation and Parameter Adaptation for Building Predictive Control
Authors: Maasoumy Mehdi , Moridian Barzin , Razmara Meysam , Shahbakhti Mahdi , Sangiovanni-Vincentelli Alberto
Published: March 2014

Model-based control of building energy offers an attractive way to minimize energy consumption in buildings. Model-based controllers require mathematical models that can accurately predict the behavior of the system. For buildings, specifically, these models are difficult to obtain due to highly time varying, and nonlinear nature of building dynamics. Also, model-based controllers often need information of all states, while not all the states of a building model are measurable. In addition, it is challenging to accurately estimate building model parameters (e.g. convective heat transfer coefficient of varying outside air). In this paper, we propose a modeling framework for “on-line estimation” of states and unknown parameters of buildings, leading to the Parameter-Adaptive Building (PAB) model. Extended Kalman filter (EKF) and unscented Kalman filter (UKF) techniques are used to design the PAB model which simultaneously tunes the parameters of the model and provides an estimate for all states of the model. The proposed PAB model is tested against experimental data collected from Lakeshore Center building at Michigan Tech University. Our results indicate that the new framework can accurately predict states and parameters of the building thermal model.
Beyond User-Specificity for EMG Decoding Using Multiresolution Muscle Synergy Analysis
Authors: Ison Mark R. , Artemiadis Panagiotis
Published: March 2014

Electromyographic (EMG) processing is a vital step towards converting noisy muscle activation signals into robust features that can be decoded and applied to applications such as prosthetics, exoskeletons, and human-machine interfaces. Current state of the art processing methods involve collecting a dense set of features which are sensitive to many of the intra- and inter-subject variability ubiquitous in EMG signals. As a result, state of the art decoding methods have been unable to obtain subject independence. This paper presents a novel multiresolution muscle synergy (MRMS) feature extraction technique which represents a set of EMG signals in a sparse domain robust to the inherent variability of EMG signals. The robust features, which can be extracted in real time, are used to train a neural network and demonstrate a highly accurate and user-independent classifier. Leave-one-out validation testing achieves mean accuracy of 81.9± 3.9% and area under the receiver operating characteristic curve (AUC), a measure of overall classifier performance over all possible thresholds, of 92.4± 8.9%. The results show the ability of sparse MRMS features to achieve subject independence in decoders, providing opportunities for large-scale studies and more robust EMG-driven applications.
Simulation and Prediction of the Motion of a Human in a Vertical Jumping Task
Authors: Hariri Mahdiar , Xiang Yujiang , Chung Hyun-Joon , Bhatt Rajan , Arora Jasbir , Abdel-Malek Karim
Published: March 2014

In this work, we offer an optimization based motion prediction of a vertical jumping task for a human. The human model has 55 degrees of freedom. This is a multi-objective optimization problem where the mechanical energy and discomfort are minimized at the same time and an additional motion capture tracking objective function is used to have a more natural motion, specially for less determinant degrees of freedom in the jumping task. The problem is subject to all the Newtonian motion constraints such as ZMP constraint while on the ground and projectile motion constraints for a dynamic system (6 independent constraints that determine the changes in the net linear and angular momentum of the system) while off the ground. In this simulation the height of jump can either be specified by the user or maximized by the optimization module. This simulation is able to predict both the kinematic and dynamic effects of different inputs on the motion where kinematic effects refer to changes in the motion and dynamic effects refer to changes in forces and torques. Different inputs consist of but are not limited to: changes in the human size, mass, strength properties, changes in the mass and inertia of the equipments attached to the human and changes in the height of jump (for specified height jumps).
Maximum Power Point Tracking of Multi-String Photovoltaic Array via Simultaneous Perturbation Stochastic Approximation
Authors: Xiao Yan , Li Yaoyu , Seem John E. , Rajashekara Kaushik
Published: March 2014

This paper presents a Maximum Power Point Tracking (MPPT) strategy for multi-string photovoltaic (PV) systems using the Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm. The multi-string PV system considered is a decentralized control configuration, controlling the voltage reference to each PV module but based on the feedback of the total power at the DC bus. This requires only one pair of voltage and current measurements. The MPPT control problem for such topology of multi-string PV systems features a high input dimension, which can dramatically slow down the searching process for the real-time optimization process involved. The SPSA algorithm is considered in this study due to its remarkable capability of fast convergence for high dimensional search problems endorsed by various applications recently. Simulation study is performed for an 8-string PV system, and experimental study is performed for a 4-string PV system. Good performances are observed for both simulation and experimental results.
Relation Between End-Effector Impedance and Joint Friction of Statically-Balanced Mechanisms
Authors: Xiu Wenwu , Ma Ou
Published: March 2014

Statically-balanced mechanisms have been widely used for passive compensation of gravity loads in many applications including neurological rehabilitation and micro-/reduced-gravity simulation. For these applications, it is desirable that the used mechanism has minimal impedance the interacting human can feel. Impedance of a statically-balanced mechanism is contributed by many factors including the payload on the end-effector and the joint friction. This paper studies the relation between the end-effector impedance and the load-dependent joint friction for statically-balanced mechanisms. In the study a load dependent joint friction force model was developed. With the model, contribution of the end-effector load or payload on the joint friction can be evaluated, from which the end-effector impedance of the mechanism caused by the joint friction can be computed. The study results are applied to the analysis of a reduced-gravity simulator to evaluate the effect of the joint friction on the end-effector impedance of the mechanism. The findings of the study can help the assessment of the dynamic performance and also help the optimal design of statically-balanced mechanisms.
Control of Highly Organized Nanostructures in Microchannels Using Nanoliter Droplets
Authors: Choi Eunpyo , Kwon Kilsung , Chang Hyung-kwan , Kim Daejoong , Park Jungyul
Published: March 2014

In this study, we introduce a novel method for control of self-organization of nanoparticles in microchannels using the control of nanoliter droplets and show its useful applications. By controlling capillary force and evaporation process, nanoparticles can be assembled at the desired area and they can be used from nanoporous membranes to biosensor itself. As the biosensor applications, biologically inspired humidity sensor and IgG antibody detector were developed. They can recognize the target materials by the change of visual color without using any fluorescent probe and external electrical power source. These highly organized nanoparticles also induce the unique nanoelectrokinetics, which open new application fields such as such as separation, filtering, accumulation, and analysis of biomolecules, energy generation, and optofluidic system. Among them, we introduce two techniques that are diffuse based chemical gradient generation and sea water desalination.
Inductively coupled plasma reactive ion etching of GaAs wafer pieces with enhanced device yield
Authors: Connors Michael K. , Missaggia Leo J. , Spencer William S. , Turner George W.
Published: March 2014

Inductively coupled plasma reactive ion etching (ICP-RIE) is used in the fabrication of GaAs slab-coupled optical waveguide (SCOW) laser and amplifier devices in order to prepare etched-ridge-waveguide surface features. The processing of GaAs wafer pieces (less than full wafers) requires mounting these samples on a ceramic or silicon carrier wafer by means of a thermally conductive mounting paste to improve thermal contact between the GaAs and carrier wafer. However, use of a mounting paste requires additional postetch handling of samples, including mechanical clean-up and multiple solvent cleaning steps. Insufficient paste removal can lead to unwanted surface contamination and film adhesion issues during subsequent sample processing. Massachusetts Institute of Technology Lincoln Laboratory has developed an ICP-RIE process for GaAs wafer pieces that eliminates the use of mounting paste. This process features time-limited thermal management during etching, which is essential to maintain predictable etch rates along with suitable etched surfaces and satisfactory sidewall quality. Utilizing this simplified etch process for SCOW fabrication has resulted in greatly reduced film adhesion failures and a dramatic improvement in device yield.
Inhibition of initial bacterial adhesion on titanium surfaces by lactoferrin coating
Authors: Nagano-Takebe Futami , Miyakawa Hiroshi , Nakazawa Futoshi , Endo Kazuhiko
Published: March 2014

Because dental implant abutments are located at transmucosal sites, their surface should inhibit bacterial accumulation to prevent peri-implantitis. The authors examined the effects of human lactoferrin (LF), an antibacterial protein present in saliva, as an antibacterial coating on the titanium surface and evaluated its effects before and after mucin-containing artificial saliva (AS) incubation. In the control group, titanium disks were soaked in distilled water, whereas in the LF group, titanium disks were soaked in LF solution to coat the disks. In the control-AS and LF-AS groups, half of the control and LF disks were incubated with AS. To confirm LF adsorption, the fluorescence intensity of fluorescein isothiocyanate-labeled LF was measured. The LF and LF-AS groups showed significantly higher intensity than the control and control-AS groups (P < 0.01). There was no significant difference between the LF and LF-AS groups (P > 0.05). The amount of adhered Streptococcus gordonii significantly increased by incubation with AS (P < 0.01) and significantly decreased by adsorption of LF (P < 0.01). There was no interaction between the two factors, LF adsorption and AS incubation (P = 0.561). These results suggest that the adsorbed LF inhibited bacterial adhesion following AS incubation. According to qualitative LIVE/DEAD analysis, viable bacteria appeared to be decreased in the presence of LF and SEM observation indicated that altered morphologies increased in LF and LF-AS groups. These results suggest that the adsorbed LF remained on the titanium surface after incubation with AS, and the remaining LF inhibited bacterial adhesion and exhibited bactericidal effects. Therefore, the adsorption of LF on the abutment material appears to be effective in preventing peri-implantitis.
Accelerations of the Waist and Lower Extremities Over a Range of Gait Velocities to Aid in Activity Monitor Selection for Field-Based Studies
Authors: Morrow Melissa M.B. , Hurd Wendy J. , Fortune Emma , Lugade Vipul , Kaufman Kenton R.
Published: March 2014

This study aimed to define accelerations measured at the waist and lower extremities over a range of gait velocities to provide reference data for choosing the appropriate accelerometer for field-based human activity monitoring studies. Accelerations were measured with a custom activity monitor (± 16g) at the waist, thighs, and ankles in 11 participants over a range of gait velocities from slow walking to running speeds. The cumulative frequencies and peak accelerations were determined. Cumulative acceleration amplitudes for the waist, thighs, and ankles during gait velocities up to 4.8 m/s were within the standard commercial g-range (± 6g) in 99.8%, 99.0%, and 96.5% of the data, respectively. Conversely, peak acceleration amplitudes exceeding the limits of many commercially available activity monitors were observed at the waist, thighs, and ankles, with the highest peaks at the ankles, as expected. At the thighs, and more so at the ankles, nearly 50% of the peak accelerations would not be detected when the gait velocity exceeds a walking velocity. Activity monitor choice is application specific, and investigators should be aware that when measuring high-intensity gait velocity activities with commercial units that impose a ceiling at ± 6g, peak accelerations may not be measured.
The Experience of Competition Ban Following a Positive Doping Sample of Elite Athletes
Authors: Georgiadis Emmanouil , Papazoglou Irini
Published: March 2014

World Anti-Doping Association (WADA) is responsible for doping-free sporting contests and is the only sporting body posing relevant competition sanctions. While doping relates to various controversial attitudes and beliefs proposed in the past, the confirmation of a competition ban following a doping violation has many negative connotations for the lives of the athletes. This can elicit multiple significant and far-reaching implications for them and their close ones. Aiming to better understand these implications in an athlete’s life, 5 Greek male and female athletes having recently received a competition ban after a doping violation were interviewed. Qualitative analysis of the data showed that many important psychological, social, and financial implications follow such a sanction. Most importantly, these consequences may even contribute to indications of poor mental and physical health. Discussion of the results provides suggestions for the alleviation of the negative consequences following an involuntary sporting career pause or termination.
Bordetella pertussis Proteins Dominating the Major Histocompatibility Complex Class II-Presented Epitope Repertoire in Human Monocyte-Derived Dendritic Cells
Authors: Stenger Rachel M. , Meiring Hugo D. , Kuipers Betsy , Poelen Martien , van Gaans-van den Brink Jacqueline A. M. , Boog Claire J. P. , de Jong Ad P. J. M. , van Els Cécile A. C. M.
Published: March 2014

Knowledge of naturally processedBordetella pertussis-specific T cell epitopes may help to increase our understanding of the basis of cell-mediated immune mechanisms to control this reemerging pathogen. Here, we elucidate for the first time the dominant major histocompatibility complex (MHC) class II-presentedB. pertussisCD4+T cell epitopes, expressed on human monocyte-derived dendritic cells (MDDC) after the processing of whole bacterial cells by use of a platform of immunoproteomics technology. Pertussis epitopes identified in the context of HLA-DR molecules were derived from two envelope proteins, i.e., putative periplasmic protein (PPP) and putative peptidoglycan-associated lipoprotein (PAL), and from two cytosolic proteins, i.e., 10-kDa chaperonin groES protein (groES) and adenylosuccinate synthetase (ASS). No epitopes were detectable from known virulence factors. CD4+T cell responsiveness in healthy adults against peptide pools representing epitope regions or full proteins confirmed the immunogenicity of PAL, PPP, groES, and ASS. Elevated lymphoproliferative activity to PPP, groES, and ASS in subjects within a year after the diagnosis of symptomatic pertussis suggested immunogenic exposure to these proteins during clinical infection. The PAL-, PPP-, groES-, and ASS-specific responses were associated with secretion of functional Th1 (tumor necrosis factor alpha [TNF-α] and gamma interferon [IFN-γ]) and Th2 (interleukin 5 [IL-5] and IL-13) cytokines. Relative paucity in the naturalB. pertussisepitope display of MDDC, not dominated by epitopes from known protective antigens, can interfere with the effectiveness of immune recognition ofB. pertussis. A more complete understanding of hallmarks inB. pertussis-specific immunity may advance the design of novel immunological assays and prevention strategies.
Clinical Significance and Characterization of Haemophilus influenzae Type b Genogroup Isolates from Urine Samples in an Adult Male Population
Authors: Dingle Tanis C. , Clarridge Jill E.
Published: March 2014

The occurrence and significance of
Haemophilus
spp. isolated from the genitourinary tract are not well known. Herein, we describe the clinical significance and characteristics of
Haemophilus influenzae
type b genogroup strains isolated from genitourinary tract specimens from an adult male veteran patient population and, in particular, their associations with prostatitis and epididymitis.
Implication of the Bacterial Endosymbiont Rickettsia spp. in Interactions of the Whitefly Bemisia tabaci with Tomato yellow leaf curl virus
Authors: Kliot Adi , Cilia Michelle , Czosnek Henryk , Ghanim Murad
Published: March 2014

Numerous animal and plant viruses are transmitted by arthropod vectors in a persistent, circulative manner.
Tomato yellow leaf curl virus
(TYLCV) is transmitted by the sweet potato whitefly
Bemisia tabaci
. We report here that infection with
Rickettsia
spp., a facultative endosymbiont of whiteflies, altered TYLCV-
B. tabaci
interactions. A
B. tabaci
strain infected with
Rickettsia
acquired more TYLCV from infected plants, retained the virus longer, and exhibited nearly double the transmission efficiency compared to an uninfected
B. tabaci
strain with the same genetic background. Temporal and spatial antagonistic relationships were discovered between
Rickettsia
and TYLCV within the whitefly. In different time course experiments, the levels of virus and
Rickettsia
within the insect were inversely correlated. Fluorescence
in situ
hybridization analysis of
Rickettsia
-infected midguts provided evidence for niche exclusion between
Rickettsia
and TYLCV. In particular, high levels of the bacterium in the midgut resulted in higher virus concentrations in the filter chamber, a favored site for virus translocation along the transmission pathway, whereas low levels of
Rickettsia
in the midgut resulted in an even distribution of the virus. Taken together, these results indicate that
Rickettsia
, by infecting the midgut, increases TYLCV transmission efficacy, adding further insights into the complex association between persistent plant viruses, their insect vectors, and microorganism tenants that reside within these insects.

IMPORTANCE
Interest in bacterial endosymbionts in arthropods and many aspects of their host biology in agricultural and human health systems has been increasing. A recent and relevant studied example is the influence of
Wolbachia
on dengue virus transmission by mosquitoes. In parallel with our recently studied whitefly-
Rickettsia
-TYLCV system, other studies have shown that dengue virus levels in the mosquito vector are inversely correlated with bacterial load. Our work here presents evidence of unifying principles between vectors of plant and animal viruses in a role for endosymbionts in manipulating vector biology and pathogen transmission. Our results demonstrate the influence of an interesting and prominent bacterial endosymbiont in
Bemisia tabaci
in TYLCV transmission, a worldwide disease infecting tomatoes. Besides its agricultural importance, this system provides interesting insights into
Bemisia
interaction with these newly discovered endosymbionts.
The Chicken Adenovirus Gam1 Protein, an Inhibitor of the Sumoylation Pathway, Partially Complements ICP0-Null Mutant Herpes Simplex Virus 1
Authors: Everett Roger D. , Chiocca Susanna , Orr Anne
Published: March 2014

Herpes simplex virus 1 (HSV-1) regulatory protein ICP0 stimulates efficient infection via its E3 ubiquitin ligase activity that causes degradation of several cellular proteins, some of which are sumoylated. Chicken adenovirus Gam1 protein also interferes with the sumoylation pathway, and both proteins disrupt promyelocytic leukemia protein (PML) nuclear bodies (NBs). We report that Gam1 increases the infection efficiency of ICP0-null mutant HSV-1 by approximately 100-fold, thus strengthening the hypothesis that PML NB- and sumoylation-related mechanisms are important factors in the control of HSV-1 infection.
Analysis of Host Gene Expression Changes Reveals Distinct Roles for the Cytoplasmic Domain of the Epstein-Barr Virus Receptor/CD21 in B-Cell Maturation, Activation, and Initiation of Virus Infection
Authors: Arredouani Mohamed S. , Bhasin Manoj K. , Sage David R. , Dunn Laura K. , Gill Michael B. , Agnani Deep , Libermann Towia A. , Fingeroth Joyce D.
Published: March 2014

Epstein-Barr virus (EBV) attachment to human CD21 on the B-cell surface initiates infection. Whether CD21 is a simple tether or conveys vital information to the cell interior for production of host factors that promote infection of primary B cells is controversial, as the cytoplasmic fragment of CD21 is short, though highly conserved. The ubiquity of CD21 on normal B cells, the diversity of this population, and the well-known resistance of primary B cells to gene transfer technologies have all impeded resolution of this question. To uncover the role(s) of the CD21 cytoplasmic domain during infection initiation, the full-length receptor (CD21 = CR), a mutant lacking the entire cytoplasmic tail (CT), and a control vector (NEO) were stably expressed in two pre-B-cell lines that lack endogenous receptor. Genome-wide transcriptional analysis demonstrated that stable CD21 surface expression alone (either CR or CT) produced multiple independent changes in gene expression, though both dramatically decreased class I melanoma-associated antigen (MAGE) family RNAs and upregulated genes associated with B-cell differentiation (e.g., C2TA, HLA-II, IL21R, MIC2, CD48, and PTPRCAP/CD45-associated protein). Temporal analysis spanning 72 h revealed that not only CR- but also CT-expressing lines initiated latency. In spite of this, the number and spectrum of transcripts altered in CR- compared with CT-bearing lines at 1 h after infection further diverged. Differential modulation of immediate early cellular transcripts (e.g., c-Jun and multiple histones), both novel and previously linked to CD21-initiated signaling, as well as distinct results from pathway analyses support a separate role for the cytoplasmic domain in initiation of intracellular signals.

IMPORTANCEMembrane proteins that mediate virus attachment tether virus particles to the cell surface, initiating infection. In addition, upon virus interaction such proteins may transmit signals to the interior of the cell that support subsequent steps in the infection process. Here we show that expression of the Epstein-Barr virus B-cell attachment receptor, CD21, in B cells that lack this receptor results in significant changes in gene expression, both before and rapidly following EBV-CD21 interaction. These changes translate into major signaling pathway alterations that are predicted to support stable infection.
The Crystal Structure of a Cardiovirus RNA-Dependent RNA Polymerase Reveals an Unusual Conformation of the Polymerase Active Site
Authors: Vives-Adrian Laia , Lujan Celia , Oliva Baldo , van der Linden Lonneke , Selisko Barbara , Coutard Bruno , Canard Bruno , van Kuppeveld Frank J. M. , Ferrer-Orta Cristina , Verdaguer Núria
Published: March 2014

Encephalomyocarditis virus (EMCV) is a member of the
Cardiovirus
genus within the large
Picornaviridae
family, which includes a number of important human and animal pathogens. The RNA-dependent RNA polymerase (RdRp) 3D
pol
is a key enzyme for viral genome replication. In this study, we report the X-ray structures of two different crystal forms of the EMCV RdRp determined at 2.8- and 2.15-Å resolution. The
in vitro
elongation and VPg uridylylation activities of the purified enzyme have also been demonstrated. Although the overall structure of EMCV 3D
pol
is shown to be similar to that of the known RdRps of other members of the
Picornaviridae
family, structural comparisons show a large reorganization of the active-site cavity in one of the crystal forms. The rearrangement affects mainly motif A, where the conserved residue Asp240, involved in ribonucleoside triphosphate (rNTP) selection, and its neighbor residue, Phe239, move about 10 Å from their expected positions within the ribose binding pocket toward the entrance of the rNTP tunnel. This altered conformation of motif A is stabilized by a cation-π interaction established between the aromatic ring of Phe239 and the side chain of Lys56 within the finger domain. Other contacts, involving Phe239 and different residues of motif F, are also observed. The movement of motif A is connected with important conformational changes in the finger region flanked by residues 54 to 63, harboring Lys56, and in the polymerase N terminus. The structures determined in this work provide essential information for studies on the cardiovirus RNA replication process and may have important implications for the development of new antivirals targeting the altered conformation of motif A.

IMPORTANCE
The
Picornaviridae
family is one of the largest virus families known, including many important human and animal pathogens. The RNA-dependent RNA polymerase (RdRp) 3D
pol
is a key enzyme for picornavirus genome replication and a validated target for the development of antiviral therapies. Solving the X-ray structure of the first cardiovirus RdRp, EMCV 3D
pol
, we captured an altered conformation of a conserved motif in the polymerase active site (motif A) containing the aspartic acid residue involved in rNTP selection and binding. This altered conformation of motif A, which interferes with the correct positioning of the rNTP substrate in the active site, is stabilized by a number of residues strictly conserved among picornaviruses. The rearrangements observed suggest that this motif A segment is a dynamic element that can be modulated by external effectors, either activating or inhibiting enzyme activity, and this type of modulation appears to be general to all picornaviruses.