bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of a Bi-Harmonic Tapping Mode for Atomic Force Microscopy
Authors: Loganathan Muthukumaran , Bristow Douglas A.
Published: March 2014

The tapping mode (TM) is a popularly used imaging mode in atomic force microscopy (AFM). A feedback loop regulates the amplitude of the tapping cantilever by adjusting the offset between the probe and sample; the image is generated from the control action. This paper explores the role of the trajectory of the tapping cantilever in the accuracy of the acquired image. This paper demonstrates that reshaping the cantilever trajectory alters the amplitude response to changes in surface topography, effectively altering the mechanical sensitivity of the instrument. Trajectory dynamics are analyzed to determine the effect on mechanical sensitivity and analysis of the feedback loop is used to determine the effect on image accuracy. Experimental results validate the analysis, demonstrating better than 30% improvement in mechanical sensitivity using certain trajectories. Images obtained using these trajectories exhibit improved sharpness and surface tracking, especially at high scan speeds.
Broad Frequency Vibration Energy Harvesting Control Approach Based on the Maximum Power Transfer Theorem
Authors: Pedchenko Alexander V. , Barth Eric J.
Published: March 2014

A control law for an electromagnetic vibration energy harvester is derived using the maximum power transfer theorem. Using regenerative electronics, the controller cancels the reactive portion of the harvester’s impedance by eliminating the effect of mechanical inertia and stiffness elements, and the coil’s electrical inductive element. The result is an energy harvester approach that captures more vibrational energy than a passive tuned harvester. It is shown that the controlled system acts like an infinite series of passive harvesters tuned to all frequency components within a certain frequency range. The control approach also avoids the delay and computational overhead of a Fast Fourier Transform as it does not require the explicit calculation of the excitation frequency. An experimental prototype harvester was built and characterized. The prototype’s multi-domain dynamics were modeled using bond-graph techniques, and its behavior as a passive harvester was experimentally validated. The prototype’s behavior under the proposed control method is simulated and compared to the passive case. It is shown that the proposed control method harvests more power for a range of excitation frequencies than the passive harvester.
Design of a Piezoelectric Poly-Actuated Linear Motor
Authors: Tsukahara Shinichiro , Penalver-Aguila Lluis , Torres James , Asada H. Harry
Published: March 2014

Design and analysis for an efficient and force dense piezoelectric poly-actuated linear motor is presented. A linear motor is constructed with multiple piezoelectric actuator units engaging a rod having gear teeth. The multiple piezo-units are placed along the geared rod with a particular phase difference such that a near constant force is generated regardless of the rod position by coordinating the multiple piezo-units. Rolling contact buckling mechanisms within the piezo-units provide large displacement amplification with high energy transmission and low loss properties from the piezo-units to the geared rod. This piezo-based motor has capacitive actuator characteristics which allow it to bear static loads efficiently. Furthermore, the poly-actuator architecture presented provides for scalability through modular design.

First, the basic design principle describing the engagement of buckling amplification mechanisms to a phased array-shaped gear rod is presented, and the resulting force and displacement characteristics are analyzed. Design methods for creating a piezoelectric poly-actuated linear motor are then summarized. A prototype design is presented for which a maximum mean force of 213 N, a maximum velocity of 1.125 m/s, and a force density of 41 N/kg is calculated.
Regenerative Vibration Control of Tall Buildings Using Model Predictive Control
Authors: Liu Yilun , Zuo Lei , Tang Xiudong
Published: March 2014

The regenerative Tuned Mass Damper (TMD) can convert the vibration energy of the tall building into the electricity, by replacing the damping element with electromagnetic harvester. The energy harvesting circuit therein which can regulate the electricity and control the vibration will introduce some constraints when designing vibration controller. This paper designed the vibration controller based on Model Predictive Control (MPC). The control force constraints were taken into consideration before designing the controller. The building model with semi-active constraints due to the regenerative properties of the TMD is converted into a Mixed Logical Dynamical (MLD) system first. Then the optimal controller is designed by solving the Mixed Integer Quadratic Programming (MIQP) problem. The results were evaluated and compared to the ones using “clipped-optimal” controller with the same constraints. It is found that the MPC controller can provide the same or better vibration control Results depending on the predicted horizon. Besides, an explicit MPC is obtained to reduce the online computation effort.
Asymptotic Properties of Zeros of Sampled-Data Systems for Continuous-Time Plants With Nondecouplability
Authors: Ishitobi Mitsuaki , Kunimatsu Sadaaki
Published: March 2014

When a continuous-time linear system is discretized using a hold, stability of poles are preserved. However, the transformations of zeros are much more complicated and the number of the zeros increases in some cases in the discretization process. This paper is concerned with the zeros of a sampled-data model resulting from a continuous-time multivariable system which is not decouplable by static state feedback and has all of the relative degrees one. Two cases of a zero-order hold and a fractional-order hold are treated. An approximate expression of the zeros is given as power series expansions with respect to a sampling period in the zero-order hold case. Further, the limiting zeros are analyzed in the fractional-order hold case. Then, the advantage of the fractional-order hold to the zero-order hold is discussed from the viewpoint of stability of the zeros.
Transient Control of a Hydraulic Free Piston Engine
Authors: Li Ke , Zhang Chen , Sun Zongxuan
Published: March 2014

The free piston engine (FPE) is a type of internal combustion engine (ICE) with no crankshaft, so that its piston motion is no longer constrained by mechanical linkages. The FPE has a high potential in terms of energy saving given its simple structure, high modularity and high efficiency. One of the technical barriers that prevents the wide spread of the FPE technology, is the lack of precise piston motion control. Previously, a robust repetitive controller is designed and implemented to form a virtual crankshaft that would provide a precise and stable engine operation. The experimental data of engine motoring tests with virtual crankshaft demonstrates the effectiveness of the controller. However, the presence of a transient period after a single combustion event prevents the engine from continuous firing. This paper presents a modified control scheme, which utilizes a reference and control signal shifting technique to modify the tracking error and the control signal to reduce the transient period.
A Microscale Piezoresistive Force Sensor for Nanoindentation of Biological Cells and Tissues
Authors: Pandya Hardik J. , Kim Hyun Tae , Desai Jaydev P.
Published: March 2014

We present the design and fabrication of a Micro-Electro-Mechanical Systems based piezoresistive cantilever force sensor as a potential candidate for micro/nano indentation of biological specimens such as cells and tissues. The fabricated force sensor consists of a silicon cantilever beam with a p-type piezoresistor and a cylindrical probing tip made from SU-8 polymer. One of the key features of the sensor is that a standard silicon wafer is used to make silicon-on-insulator (SOI), thereby reducing the cost of fabrication. To make SOI from standard silicon wafer the silicon film was sputtered on an oxidized silicon wafer and annealed at 1050 °C so as to obtain polycrystalline silicon. The sputtered silicon layer was used to fabricate the cantilever beam. The as-deposited and annealed silicon films were experimentally characterized using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). The annealed silicon film was polycrystalline with a low surface roughness of 3.134 nm (RMS value).
Design of a Stirling Thermocompressor for a Pneumatically Actuated Ankle-Foot Orthosis
Authors: Kumar Nithin S. , Hofacker Mark E. , Barth Eric J.
Published: March 2014

This paper presents the design, modeling, and simulated performance of a prototype Stirling thermocompressor. The thermocompressor is intended to be mounted on the back of a user’s lower leg and convert a hydrocarbon fuel source into 50 W of pneumatic power at 650 kPa to power an ankle foot orthosis. Consisting only of a displacer piston, the Stirling thermocompressor’s displacer piston motion is directly controlled by a brushless DC motor so that the frequency of operation can be tuned to output the maximum power. Simulation indicates that this operating frequency is influenced by the intended reservoir pressure and heat transfer properties of the thermocompressor.
Determination of Minimum State Preview Time to Prevent Vehicle Rollover
Authors: Stankiewicz Paul G. , Brown Alex A. , Brennan Sean N.
Published: March 2014

This research focuses on determining the minimum preview time needed to predict and prevent vehicle rollover. Statistics show that although rollover only occurs in 2.2% of total highway crashes, it accounts for 10.7% of total fatalities. There are several dynamic rollover metrics in use that measure a vehicle’s rollover propensity under specified conditions. However, in order to prevent a rollover event from occurring, it is necessary to predict a vehicle’s future rollover propensity. This research uses a novel vehicle rollover metric, called the zero-moment point (ZMP), to predict a vehicle’s rollover propensity. Comparing different amounts of preview, the results show that short-range predictions — as little as 0.75 seconds ahead of the vehicle — are sufficient to prevent nearly all dynamics-induced rollovers in typical shoulders and medians.
Cycle-by-Cycle Based In-Cylinder Temperature Estimation for Diesel Engines
Authors: Chen Song , Yan Fengjun
Published: March 2014

The in-cylinder temperature information is critical in the field of auto-ignition control in advanced combustion modes. However, the in-cylinder temperature is hard to be directly measured at low cost in production engines. In this paper, a cycle-by-cycle estimation method is proposed for the in-cylinder temperature at the crank angle of intake valve closing (IVC), referred to as Tivc. Through investigating the thermodynamics of Tivc, an Extended Kalman Filter (EKF) based method was devised by utilizing the measurable temperature information from the intake and exhaust manifolds. The proposed method was validated through high-fidelity GT-Power engine model simulation.
The Role of Model Fidelity in Model Predictive Control Based Hazard Avoidance in Unmanned Ground Vehicles Using LIDAR Sensors
Authors: Liu Jiechao , Jayakumar Paramsothy , Overholt James L. , Stein Jeffrey L. , Ersal Tulga
Published: March 2014

Unmanned ground vehicles (UGVs) are gaining importance and finding increased utility in both military and commercial applications. Although earlier UGV platforms were typically exclusively small ground robots, recent efforts started targeting passenger vehicle and larger size platforms. Due to their size and speed, these platforms have significantly different dynamics than small robots, and therefore the existing hazard avoidance algorithms, which were developed for small robots, may not deliver the desired performance. The goal of this paper is to present the first steps towards a model predictive control (MPC) based hazard avoidance algorithm for large UGVs that accounts for the vehicle dynamics through high fidelity models and uses only local information about the environment as provided by the onboard sensors. Specifically, the paper presents the MPC formulation for hazard avoidance using a light detection and ranging (LIDAR) sensor and applies it to a case study to investigate the impact of model fidelity on the performance of the algorithm, where performance is measured mainly by the time to reach the target point. Towards this end, the case study compares a 2 degrees-of-freedom (DoF) vehicle dynamics representation to a 14 DoF representation as the model used in MPC. The results show that the 2 DoF model can perform comparable to the 14 DoF model if the safe steering range is established using the 14 DoF model rather than the 2 DoF model itself. The conclusion is that high fidelity models are needed to push autonomous vehicles to their limits to increase their performance, but simulating the high fidelity models online within the MPC may not be as critical as using them to establish the safe control input limits.
A Predictor-Compensator Design to Assist Human Decision-Making Process in an Air-Traffic-Control Simulator
Authors: Sadeghzadeh Keivan , Sipahi Rifat
Published: March 2014

Air traffic control is a demanding task for human operators, as this task requires tracking multiple events, managing the events, and taking actions in the presence of multiple and possibly competing objectives. In such critical tasks, human intelligence is extremely crucial however human decisions also become more prone to errors, which could cause tragic events. One idea to prevent such errors is to design smart machines that can assist human subjects in making decisions whenever human errors become more likely. In this article, we present a simulation model that captures the essence of how a human subject model would interact with a simplified version of an air traffic control simulator, and show how we design a predictor-compensator in order to regulate and possibly improve this interaction, such that overall human-machine interface can be optimized, and human workload is reduced on average.
Simulation Based Control and its Application to a Crane System
Authors: Tagawa Yasutaka , Hashizume Yuki , Shimono Keisuke
Published: March 2014

This paper first describes a basic concept of IDCS (Inverse Dynamics Compensation via ‘Simulation of feedback control’), which is based on feedback simulation. Then, effectiveness of IDCS is demonstrated via inverse dynamics calculation of the non-linear system. In the latter half of the article, IDCS is applied to vibration control problems of a crane system with varying wire length. Several control simulations and experiments are conducted, then the effectiveness of the control system is shown.
Geometric Mechanics Based Modeling of the Attitude Dynamics and Control of Spacecraft With Variable Speed Control Moment Gyroscopes
Authors: Prabhakaran V. Sasi , Sanyal Amit K. , Leve Frederick , McClamroch N. Harris
Published: March 2014

The attitude dynamics of a spacecraft with a variable speed control moment gyroscope (VSCMG), in the presence of external torques and internal inputs, is derived using variational principles. A complete dynamics model, that relaxes some of the assumptions made in prior literature on control moment gyroscopes, is obtained. A non-standard VSCMG model, that has an offset between the center of the gimbal axis and the center of the rotor (flywheel) is considered. The dynamics equations show the complex nonlinear coupling between the internal degrees of freedom associated with the VSCMG and the spacecraft base body’s attitude degrees of freedom. Some of this coupling is induced by the non-zero offset between the gimbal axis and the rotor center. This dynamics model is then generalized to include the effects of multiple control moment gyroscopes placed in the base body with non-parallel gimbal axes. It is shown that the dynamical coupling can improve the control authority on the angular momentum of the base body of the spacecraft using changes in the momentum variables of the VSCMG. Numerical simulations confirm the use of these VSCMGs for attitude control for a given de-tumbling maneuver.
Nonlinear Control of an Unmanned Amphibious Vehicle
Authors: Alvarez Jose , Bertaska Ivan R. , von Ellenrieder Karl
Published: March 2014

The development and implementation of an experimental sliding mode control law for a 2.5 meter long unmanned amphibious vehicle (the DUKW-Ling) when waterborne is presented. A first-order sliding control surface is used for surge tracking error when a P controller is used to minimize the heading error in the system. The state of the vehicle is measured using onboard sensors with the ability to record surge, sway, yaw and position of the vehicle in real-time. Experimental data collected show the ability of the vessel to maintain a desired heading and speed. This article emphasizes the ability of sliding mode controller to respond to the unpredictable and random water and wind currents acting on the vehicle.
Stability of Connected Vehicle Platoons With Delayed Acceleration Feedback
Authors: Ge Jin I. , Avedisov Sergei S. , Orosz Gábor
Published: March 2014

Wireless vehicle-to-vehicle communication technologies such as the dedicated short range communication (DSRC) may be used to assist drivers in sensing and responding to impalpable information such as the precise acceleration of vehicles ahead. In this paper, we investigate the impact of delayed acceleration feedback on traffic flow using a nonlinear car-following model. It is shown that acceleration feedback can improve the stability of uniform traffic flow, though excessive acceleration feedback leads to undesired high frequency oscillations. Additionally, time delays in the communication channel may shrink the stable domain by introducing mid-frequency oscillations. Finally, we show that one may stabilize vehicle platoons using delayed acceleration feedback even in cases when finite driver reaction time would destabilize the system. Our results may lead to more robust cruise control systems with increased driver comfort in connected vehicle environment.
Controller Design for Nonlinear Multi-Input/Multi-Output Systems Using the Contoured Robust Controller Bode Plot
Authors: Taylor J. D. , Messner William
Published: March 2014

In this paper, a novel approach to controller design for non-linear multi–input/multi–output (MIMO) systems is presented based on the Contoured Robust Controller Bode (CRCBode) plot. CRCBode plots show level–sets of a robust metric and identify certain “forbidden regions” on the controller Bode magnitude and phase plots such that intersections of the controller frequency response with these forbidden regions indicate that a robust stability and performance criterion is violated. Nonlinear system dynamics are included as a structured uncertainty set consisting of linearizations about several operating points. To demonstrate this approach, we design a controller for a MIMO high–speed, low–tension magnetic tape drive memory system. A preliminary approximate inverse step is described, followed by several loop–shaping design iterations to eliminate all intersections with the forbidden regions on the CRCBode diagrams. Finally, the CRCBode compensator is compared to one generated using an automated H∞ synthesis algorithm.
A Method of Swing Leg Control for a Minimally Actuated Medical Exoskeleton for Individuals With Paralysis
Authors: Reid Jason I. , McKinley Michael , Tung Wayne , Pillai Minerva , Kazerooni H.
Published: March 2014

This paper discusses the control of a medical exoskeleton swing leg that has a “passive” (unactuated) knee. Previous work in legged locomotion has demonstrated the feasibility of achieving natural, energy efficient walking with minimally actuated robotic systems. This work will present early results for a medical exoskeleton that only has actuation that powers the flexion and extension of the biological hip. In this work, a hybrid model of the state dependent kinematics and dynamics of the swing leg will be developed and parameterized to yield swing hip dynamics as a function of desired knee flexion dynamics. This model is used to design swing hip motions that control the flexion behavior of the passive swing knee in a human-like manner. This concept was tested by a paraplegic user wearing a new minimally actuated exoskeleton. The presented results show that a human-like swing phase can be achieved with an exoskeleton that has fewer actuated degrees of freedom than current medical exoskeletons.
Model Predictive Sliding Mode Control: For Constraint Satisfaction and Robustness
Authors: Wang Yizhou , Chen Wenjie , Tomizuka Masayoshi , Alsuwaidan Badr N.
Published: March 2014

A novel combination of model predictive control (MPC) and sliding mode control (SMC) is presented in this paper. The motivation is to inherit the ability to explicitly deal with state and input constraints from MPC, and the good robustness property from SMC. The design of the finite-time optimal control problem and the conditions for the persistent feasibility and the closed-loop stability are discussed. Simulation results are shown to demonstrate the nominal and robust performance of the proposed control algorithm.
Interaction Control for Rehabilitation Robotics via a Low-Cost Force Sensing Handle
Authors: Erwin Andrew , Sergi Fabrizio , Chawda Vinay , O’Malley Marcia K.
Published: March 2014

This paper investigates the possibility of implementing force-feedback controllers using measurement of interaction force obtained through force-sensing resistors (FSRs), to improve performance of human interacting robots. A custom sensorized handle was developed, with the capability of simultaneously measuring grip force and interaction force during robot-aided rehabilitation therapy. Experiments are performed in order to assess the suitability of FSRs to implement force-feedback interaction controllers. In the force-feedback control condition, the applied force for constant speed motion of a linear 1DOF haptic interface is reduced 6.1 times compared to the uncontrolled condition, thus demonstrating the possibility of improving transparency through force-feedback via FSRs.
A Haptic System for Educational Games: Design and Application-Specific Kinematic Optimization
Authors: Kessler Jeffrey A. , Lovelace R. Curtis , Okamura Allison M.
Published: March 2014

HAPTIC PONG is a force-feedback version of the classic arcade game “Pong”, conceived as an educational game that can teach physics and controls concepts to high school students. Our design incorporates two identical linear one-degree-of-freedom haptic paddles, each with a four-bar linkage transforming motor rotation to linear motion. Virtual environments were designed to incorporate dynamic systems describing the force-displacement relationships of each paddle. At a demonstration with 50 high school students, a prototype of the device was rated as both educational and fun to use. After the initial proof of concept, a design optimization study was conducted to improve the kinematic performance of the linear haptic devices based on the device constraints for the application. Optimization considered both the linearity of the coupler point and Jacobian minimum singular value. While maintaining a satisfactory level of linearity, the optimized linkage lengths produced an estimated 160% improvement in the maximum consistent force output.
Vehicle Stability Control in Anti-Lock Braking System on Split-U Road Surface Considering Driver in the Loop
Authors: Yu Liangyao , You Changxi , Song Jian
Published: March 2014

With the introduction and development of Anti-lock Braking System in modern vehicles, remarkable progress in brake efficiency and brake stability has been achieved. However, it is a significant challenge to deal with the control law in certain critical situations, especially on split-μ road surface. In low vehicle velocity, as some standards and regulations specified, the stability in such situation is comparably easy to be achieved. But with the vehicle velocity increasing, the driver behavior contributes a large impact on the trajectory maintenance and easily causes sympathetic vibration of the vehicle because of the unexpected synchronization between the driver input and control law output, which could be very dangerous. This paper presents the research work in vehicle stability control when Anti-lock Braking System is activated at split-μ road surface. The principal contribution of this work is that the driver behavior is taken into account and the control law is tuned to adapt to this situation, which effectively maintains the stability of the vehicle without compromising the brake efficiency.
On-Line Fault Detection and Isolation (FDI) for the Exhaust Path of a Turbocharged SI Engine
Authors: Salehi Rasoul , Shahbakhti Mahdi , Alasty Aria , Vossoughi Gholamreza
Published: March 2014

Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold’s input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically shown to be robust to the faults in the exhaust manifold. The output flow of the exhaust manifold is detected by a sliding mode observer. The designed fault diagnosis and isolation (FDI) strategy is tested with the experimental data collected from a 1.7-liter turbocharged SI engine. The validation results show that the FDI strategy can detect a leakage fault from a 5mm hole in the exhaust manifold, and can identify the wastegate stuck faults.
Development of a Variable Electromotive-Force Generator With an Active Control System
Authors: Zhu W. D. , Goudarzi N. , Wang X. F. , Kendrick P.
Published: March 2014

A variable electromotive-force generator (VEG), which is a modified generator with an adjustable overlap between the rotor and the stator, is proposed to improve the efficiency and/or expand the operational range of a conventional generator, with particular applications to wind turbines, hybrid vehicles, and so on. A mathematical model of the VEG is developed, and a novel prototype is designed and fabricated. The performance of the VEG with the active control system, which adjusts the overlap ratio based on the desired output power at different input speeds, is theoretically and experimentally studied. The results show that reducing the overlap between the rotor and the stator of the generator at low speeds results in a reduced torque loss of the generator and an increased rotational speed of the generator rotor.
Timoshenko Beam Model for Exploration and Sensing With a Continuum Centipede Inspired Robot
Authors: Fattahi Javad S. , Spinello Davide
Published: March 2014

We present the continuum model of a robot inspired by organisms like centipedes and polychaete worms. The continuum model is obtained as the limit of a rigid body chain with pinned elements, which leads to a Timoshenko beam model that is described by a one dimensional continuum with local Euclideian structure. The local Euclideian structure models the cross sections that are kinematically described by their position and orientation. The leg structures in the biological systems are modeled in the continuum limit as a distribution of compliant elements. Modal properties of the system are investigated. The compliance of the legs can be exploited for sensing purposes with specific application to the reconstruction of the surrounding environment and to the estimation of physical properties. The class of models in this papers applies to the continuum description of several emerging robotic application that range from tools for exploration in hazardous or generally not accessible environments (to humans) to novel healthcare systems as for example endoscopic tools for diagnostic in the gastrointestinal tract.
Evaluation of a 12-Month Coping Intervention Intended to Enhance Future-Oriented Coping in Goal-Oriented Domains
Authors: Devonport Tracey J. , Lane Andrew M.
Published: March 2014

The present study used a mixed methods approach to evaluate the usage and perceived effectiveness of a 12-month coping intervention. Twelve junior national netball players followed an intervention that had two objectives: 1) to encourage the use of future-oriented coping across goal-oriented contexts and 2) to facilitate resource accumulation and maintenance by developing coping related competencies. Mentors and players maintained reflective diaries throughout the intervention and were contacted via telephone or e-mail every 2–3 months. In addition, players completed the Brief COPE measure at 1, 6, and 12 months. Eight players and 8 mentors completed postintervention interviews. Data indicated that following completion of the intervention, players perceived themselves to have a better understanding of when and how to use future-oriented coping. They also perceived enhanced psychosocial resources, and a more flexible approach toward goal pursuits. Recommendations for future research developments and the evaluation of coping interventions are presented.
Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV
Authors: Ivanov Maya I. , Hill Jim , Bliska James B.
Published: March 2014

Plague is an acute infection caused by the Gram-negative bacteriumYersinia pestis. Antibodies that are protective against plague target LcrV, an essential virulence protein and component of a type III secretion system ofY. pestis. Secreted LcrV localizes to the tips of type III needles on the bacterial surface, and its function is necessary for the translocation ofYersiniaouter proteins (Yops) into the cytosol of host cells infected byY. pestis. Translocated Yops counteract macrophage functions, for example, by inhibiting phagocytosis (YopE) or inducing cytotoxicity (YopJ). Although LcrV is the best-characterized protective antigen ofY. pestis, the mechanism of protection by anti-LcrV antibodies is not fully understood. Antibodies bind to LcrV at needle tips, neutralize Yop translocation, and promote opsonophagocytosis ofY. pestisby macrophagesin vitro. However, it is not clear if anti-LcrV antibodies neutralize Yop translocation directly or if they do so indirectly, by promoting opsonophagocytosis. To determine if the protective IgG1 monoclonal antibody (MAb) 7.3 is directly neutralizing, an IgG2a subclass variant, a deglycosylated variant, F(ab′)2, and Fab were tested for the ability to inhibit the translocation of Yops intoY. pestis-infected macrophagesin vitro. Macrophage cytotoxicity and cellular fractionation assays show that the Fc of MAb 7.3 is not required for the neutralization of YopJ or YopE translocation. In addition, the use of Fc receptor-deficient macrophages, and the use of cytochalasin D to inhibit actin polymerization, confirmed that opsonophagocytosis is not required for MAb 7.3 to neutralize translocation. These data indicate that the binding of the variable region of MAb 7.3 to LcrV is sufficient to directly neutralize Yop translocation.
Molecular Method Development and Establishment of a Database for Clinical and Epidemiological Herpes Simplex Virus 1 Strain Comparisons
Authors: Dean Amy B. , St. George Kirsten
Published: March 2014

Previous methods of herpes simplex virus 1 (HSV-1) genotype analysis have lacked sufficient discriminatory power for strain analysis within genotypes. The hypervariable reiterative repeat regions in the US1 and US12 introns, known as ReIV, were targeted for strain comparison. PCR methods for these extremely GC-rich target regions were optimized to give reproducible amplicons that were visualized by capillary electrophoresis relative to size standards. Analysis of the size, shape, and pattern of the resulting signatures enabled strain discrimination. Primary clinical specimens were used to develop the assay and the analysis algorithm. A blinded clinical study of 147 in-state and 51 out-of-state samples, including matched specimen-isolate pairs, was then performed. All primary clinical samples had been collected between 2004 and 2011 for viral diagnosis and previously found to be positive for HSV-1 by real-time PCR. The combined database contained patterns from 264 samples collected from 199 patients with a total of 176 unique signatures, none of which were dominant in the population. Matches between the signatures of the more than 50 specimen-isolate pairs were always seen. Signatures also matched across multiple samples collected from individual patients (six such cases), as well as some additional signature matches where epidemiological links were likely. Results were reproducible on repeat testing of individual specimens, even after months in frozen storage. The protocol has multiple potential clinical and public health uses.
Cardiolipin Synthetase Is Involved in Antagonistic Interaction (Reverse CAMP Phenomenon) of Mycoplasma Species with Staphylococcus aureus Beta-Hemolysis
Authors: Kornspan Jonathan D. , Rottem Shlomo , Nir-Paz Ran
Published: March 2014

Mycoplasma hyorhinishas been implicated in a variety of swine diseases. However, little is known about the hemolytic capabilities ofMycoplasmaspecies in general orM. hyorhinisin particular. In this study, we show thatM. hyorhinispossesses beta-hemolytic activity which may be involved in the invasion process.M. hyorhinisalso possesses antagonistic cooperativity (reverse CAMP phenomenon) withStaphylococcus aureusbeta-hemolysis, resulting in the protection of erythrocytes from the beta-hemolytic activity ofS. aureus(reverse CAMP). The reversed CAMP phenomenon has been attributed to phospholipase D (PLD) activity.In silicoanalysis of theM. hyorhinisgenome revealed the absence of thepldgene but the presence of theclsgene encoding cardiolipin synthetase, which contains two PLD active domains. The transformation ofMycoplasma gallisepticumthat has neither theclsgene nor the reverse CAMP phenomenon with theclsgene fromM. hyorhinisresulted in the reverse CAMP phenomenon, suggesting for the first time that reverse CAMP can be induced by cardiolipin synthetase.
Genotypes of Klebsiella oxytoca Isolates from Patients with Nosocomial Pneumonia Are Distinct from Those of Isolates from Patients with Antibiotic-Associated Hemorrhagic Colitis
Authors: Herzog Kathrin A. T. , Schneditz Georg , Leitner Eva , Feierl Gebhard , Hoffmann Karl Martin , Zollner-Schwetz Ines , Krause Robert , Gorkiewicz Gregor , Zechner Ellen L. , Högenauer Christoph
Published: March 2014

Klebsiella oxytoca
acts as a pathobiont in the dysbiotic human intestinal microbiota, causing antibiotic-associated hemorrhagic colitis (AAHC), but it also infects other organs, resulting in pneumonia and urinary tract and skin infections. The virulence of
K. oxytoca
is still poorly understood. The production of a specific cytotoxin has been linked to AAHC pathogenesis. To investigate the clonal relationships of
K. oxytoca
with regard to clinical origin and virulence attributes, we established a multilocus sequence typing (MLST) method and analyzed 74 clinical
K. oxytoca
isolates from asymptomatic carriers and patients with AAHC, respiratory infections, and other infections. The isolates were phenotypically characterized, typed, and compared phylogenetically based on the sequences of seven housekeeping genes. MLST analysis yielded 60 sequence types, 12 of which were represented by more than one isolate. The phylogenetic tree distinguished clusters of
K. oxytoca
isolates between patients with AAHC and those with respiratory infections. Toxin-positive and -negative strains were observed within one sequence type. Our findings indicate that AAHC isolates share a genetic background. Interestingly,
K. oxytoca
isolates from nosocomial pneumonia showed a different genetic clustering, suggesting that these strains do not originate from the intestines or that they are specialized for respiratory tract colonization. Our results further indicate a polyphyletic origin and possible horizontal transfer of the genes involved in
K. oxytoca
cytotoxin production. This work provides evidence that
K. oxytoca
isolates colonizing the two main clinically relevant habitats (lower gastrointestinal [GI] tract and respiratory tract) of the human host are genetically distinct. Applications of this MLST analysis should help clarify the sources of nosocomial infections.
Highly Specific Salt Bridges Govern Bacteriophage P22 Icosahedral Capsid Assembly: Identification of the Site in Coat Protein Responsible for Interaction with Scaffolding Protein
Authors: Cortines Juliana R. , Motwani Tina , Vyas Aashay A. , Teschke Carolyn M.
Published: March 2014

Icosahedral virus assembly requires a series of concerted and highly specific protein-protein interactions to produce a proper capsid. In bacteriophage P22, only coat protein (gp5) and scaffolding protein (gp8) are needed to assemble a procapsid-like particle, both
in vivo
and
in vitro
. In scaffolding protein's coat binding domain, residue R293 is required for procapsid assembly, while residue K296 is important but not essential. Here, we investigate the interaction of scaffolding protein with acidic residues in the N-arm of coat protein, since this interaction has been shown to be electrostatic. Through site-directed mutagenesis of genes 5 and 8, we show that changing coat protein N-arm residue 14 from aspartic acid to alanine causes a lethal phenotype. Coat protein residue D14 is shown by cross-linking to interact with scaffolding protein residue R293 and, thus, is intimately involved in proper procapsid assembly. To a lesser extent, coat protein N-arm residue E18 is also implicated in the interaction with scaffolding protein and is involved in capsid size determination, since a cysteine mutation at this site generated petite capsids. The final acidic residue in the N-arm that was tested, E15, is shown to only weakly interact with scaffolding protein's coat binding domain. This work supports growing evidence that surface charge density may be the driving force of virus capsid protein interactions.

IMPORTANCE
Bacteriophage P22 infects
Salmonella enterica
serovar Typhimurium and is a model for icosahedral viral capsid assembly. In this system, coat protein interacts with an internal scaffolding protein, triggering the assembly of an intermediate called a procapsid. Previously, we determined that there is a single amino acid in scaffolding protein required for P22 procapsid assembly, although others modulate affinity. Here, we identify partners in coat protein. We show experimentally that relatively weak interactions between coat and scaffolding proteins are capable of driving correctly shaped and sized procapsids and that the lack of these proper protein-protein interfaces leads to aberrant structures. The present work represents an important contribution supporting the hypothesis that virus capsid assembly is governed by seemingly simple interactions. The highly specific nature of the subunit interfaces suggests that these could be good targets for antivirals.
Depletion of the cdk Inhibitor p16
INK4a
Differentially Affects Proliferation of Established Cervical Carcinoma Cells
Authors: Pauck Alexander , Lener Barbara , Hoell Monika , Kaiser Andreas , Kaufmann Andreas M. , Zwerschke Werner , Jansen-Dürr Pidder
Published: March 2014

Infections with high-risk human papillomaviruses (hrHPV) contribute to cervical carcinoma. The cdk inhibitor and tumor suppressor p16
INK4A
is consistently upregulated in cervical carcinoma cells for reasons that are poorly understood. We report here that downregulation of p16
INK4A
gene expression in three different cervical carcinoma cell lines reduced expression of the E7 oncogene, suggesting a positive feedback loop involving E7 and p16
INK4A
. p16
INK4A
depletion induced cellular senescence in HeLa but not CaSki and MS-751 cervical carcinoma cells.

IMPORTANCE
This study demonstrates that the cdk inhibitor p16
INK4A
, frequently used as surrogate marker for transforming infections by human papillomaviruses of the high-risk group, is required for high-level expression of the E7 oncoproteins of HPV-16, HPV-18, and HPV-45 in cervical carcinoma cells. It is also demonstrated that depletion of p16
INK4A
induces senescence in HeLa but not CaSki or MS-751 cervical carcinoma cells.
Mental disorders and the desire for death in patients receiving palliative care for cancer
Authors: Wilson Keith G , Dalgleish Tracy L , Chochinov Harvey Max , Chary Srini , Gagnon Pierre R , Macmillan Karen , De Luca Marina , O'Shea Fiona , Kuhl David , Fainsinger Robin L
Published: March 2014

Objectives

The desire for death in terminally ill patients is associated with depression and anxiety, but not all patients who report it meet criteria for mental disorders. We examined the characteristics of subgroups of palliative cancer patients who expressed a desire for death that occurred either with or without a concurrent depressive or anxiety disorder.

Design

Cross-sectional survey.

Setting

Eight Canadian palliative care programs.

Participants

377 patients with cancer.

Main outcome measures

Desire for Death Rating Scale; Structured Interview of Symptoms and Concerns.

Results

Most participants (69.5%) had no desire for death. Of the remainder, 69 (18.3%) acknowledged occasional transient thoughts, and 46 (12.2%) reported an apparently genuine desire to die. In the latter group, 24 individuals (52.2%) were diagnosed with a mental disorder and 22 (44.8%) were not. Individuals with no serious desire for death and no mental disorder reported the least distress in physical, social, existential, and psychological symptoms and concerns; those with a mental disorder and a significant desire for death reported the most. The subgroup of patients with a serious desire for death but no concurrent mental disorders still reported increased distress due to physical symptoms and social concerns, as well as a higher prevalence of global suffering.

Conclusions

The expression of a desire for death by a terminally ill patient should raise a suspicion about mental health problems, but is not in itself clearly indicative of one. Nevertheless, it may serve as a catalyst to review the individual's physical symptom management and interpersonal concerns, and overall sense of suffering.
Are you prepared? Managing disasters
Authors: Breton Amy
Published: March 2014

Disasters can occur at any time and at any place; they can be unpredictable and have a wide range of variation. Based on her experience in the USA, Amy Breton describes the important role that vets can play in their communities and how they can help during these challenging events.
EVALUATION AND APPLICATION OF A HYBRID BRAIN COMPUTER INTERFACE FOR REAL WHEELCHAIR PARALLEL CONTROL WITH MULTI-DEGREE OF FREEDOM
Authors: LI JIE , JI HONGFEI , CAO LEI , ZANG DI , GU RONG , XIA BIN , WU QIANG
Published: March 2014

There have been many attempts to design brain–computer interfaces (BCIs) for wheelchair control based on steady state visual evoked potential (SSVEP), event-related desynchronization/synchronization (ERD/ERS) during motor imagery (MI) tasks, P300 evoked potential, and some hybrid signals. However, those BCI systems cannot implement the wheelchair navigation flexibly and effectively. In this paper, we propose a hybrid BCI scheme based on two-class MI and four-class SSVEP tasks. It cannot only provide multi-degree control for its user, but also allow the user implement the different types of commands in parallel. In order for the subject to learn the hybrid mental strategies effectively, we design a visual and auditory cues and feedback-based training paradigm. Furthermore, an algorithm based on entropy of classification probabilities is proposed to detect intentional control (IC) state for hybrid tasks, and ensure that multi-degree control commands are accurately and quickly generated. The experiment results attest to the efficiency and flexibility of the hybrid BCI for wheelchair control in the real-world.
Bifurcation and global dynamical behavior of the f(T) theory
Authors: Feng Chao-Jun , Li Xin-Zhou , Liu Li-Yan
Published: March 2014

Usually, in order to investigate the evolution of a theory, one may find the critical points of the system and then perform perturbations around these critical points to see whether they are stable or not. This local method is very useful when the initial values of the dynamical variables are not far away from the critical points. Essentially, the nonlinear effects are totally neglected in such kind of approach. Therefore, one cannot tell whether the dynamical system will evolute to the stable critical points or not when the initial values of the variables do not close enough to these critical points. Furthermore, when there are two or more stable critical points in the system, local analysis cannot provide the information on which the system will finally evolute to. In this paper, we have further developed the nullcline method to study the bifurcation phenomenon and global dynamical behavior of the f(T) theory. We overcome the shortcoming of local analysis. And, it is very clear to see the evolution of the system under any initial conditions.
Role of Information in Decision Making of Social Agents
Authors: Yukalov Vyacheslav I. , Sornette Didier
Published: March 2014

The influence of additional information on the decision making of agents, who are the interacting members of a society, is analyzed within the mathematical framework based on the use of quantum probabilities. The introduction of social interactions, which influence the decisions of individual agents, leads to a generalization of the quantum decision theory (QDT) developed earlier by the authors for separate individuals. The generalized approach is free of the standard paradoxes of classical decision theory. This approach also explains the error-attenuation effects observed for the paradoxes occurring when decision makers, who are members of a society, consult with each other, increasing in this way the available mutual information. A precise correspondence between QDT and classical utility theory is formulated via the introduction of an intermediate probabilistic version of utility theory of a novel form, which obeys the requirement that zero-utility prospects should have zero probability weights.
Evaluation of Heuristics Using Data Envelopment Analysis
Authors: Lu Chung-Cheng Jason , Wu Yen-Chun Jim
Published: March 2014

This paper focuses on identifying relatively efficient configurations of algorithmic operators among a set of configurations in the development of heuristics or meta-heuristics. Each configuration is considered as a decision-making unit with multiple inputs and outputs. Then, data envelopment analysis (DEA) is adopted to evaluate relative and cross-efficiencies of a set of algorithmic configurations. The proposed approach differs from existing methods based on statistical tests in that multiple inputs and outputs are simultaneously considered in an integrated framework for the evaluation of algorithmic efficiency. A case study is presented to demonstrate the application of DEA for determining the efficient configurations of genetic algorithm operators. The evaluation results of two DEA models are also compared. The DEA evaluation results are consistent with those obtained by a commonly used statistical method.