bluuebunny/crossref_metadata_2025 huggingface dataset:
A Plant-Inversion Based Switched Iterative Learning Control Scheme for a Special Class of Multivariable Systems
Authors: Li He , Bristow Douglas A. , Landers Robert G.
Published: November 2018

This paper presents a plant-inversion based Switched Iterative Learning Control (SILC) scheme for a special class of Multi-Input Multi-Output (MIMO) systems for which only one output channel can be accessed at any given time. While Asymptotic Stability (AS), or zero error convergence, is predominantly considered in Iterative Learning Control (ILC), AS cannot be achieved for this class of systems. A weaker condition, bounded convergence, however, can be obtained. With the SILC scheme proposed in this paper, the measurement channels are accessed one at a time in a specific order. Each time an output channel is accessed, bounded convergence of all of the channel errors is achieved by using an ILC algorithm. As the access is switched from one channel to the next, the previously achieved convergent error is brought to a new value due to the change of measurement information, which may or may not be less than the previous one, depending on the structure of the learning matrix. Using the inverse plant dynamics as a learning matrix and as the switching action continues occurring, the bounded convergence tends to zero convergence. Illustrative examples are provided to demonstrate the effectiveness of the proposed SILC scheme and its robustness to modeling uncertainty.
Modeling and Control of Artificial Swimming Bladder Enabled by IPMC Water Electrolysis
Authors: Keow Alicia , Chen Zheng
Published: November 2018

Underwater robots with buoyancy control capability are highly desirable in deep ocean exploration for underwater environment monitoring and intelligent collection. In this paper, a prototype of buoyancy control device powered by ionic polymer metal composite (IPMC) is developed. An IPMC is used for enhancing the water electrolysis of tap water and separating the gases produced. The produced hydrogen and oxygen gases are stored in two separate chambers. Collection of these gases increase the volume of water displaced by the device, hence, increases its buoyancy. Two solenoid valves are used to control the release of gases to decrease the device’s buoyancy. Using a dynamic model developed in our previous work, the parameters of the model are identified through an open-loop test. A PID controller is then designed for close-loop depth control. The PID controller uses the error in depth to estimate the desired gas generation/releasing rate. It then calculates the duty cycle of the pulse-width modulation (PWM) signal used for driving the solenoid valves. The closed-loop depth control is verified both through simulation and real-time experiment, showing satisfactory results.
Development and Experimental Validation of an Energy Regenerative Prosthetic Knee Controller and Prototype
Authors: Khalaf Poya , Warner Holly , Hardin Elizabeth , Richter Hanz , Simon Dan
Published: November 2018

We present the design, control, and experimental evaluation of an energy regenerative powered transfemoral prosthesis. Our prosthesis prototype is comprised of a passive ankle and a powered knee joint. The knee joint is actuated by an ultracapacitor based regenerative drive mechanism. A novel varying impedance control approach controls the prosthesis in both the stance and swing phase of the gait cycle, while explicitly considering energy regeneration. This control method varies the impedance of the knee joint based on the amount of force exerted on the shank of the prosthesis. Furthermore, the controller promotes energy regeneration by precisely injecting a designated amount of negative damping into the system. Our control approach leads to a few tuning parameters that cover all of the gait phases for walking and all of the tested walking speeds and eliminates the need for tedious target impedance scheduling. Experimental evaluation is done with an amputee test subject walking at different speeds on a treadmill. The results validate the effectiveness of the control method. In addition, net energy regeneration is achieved while walking with near-natural gait across all speeds.
Grasp Force Sensing Using Visual Servoing and Fingernail Imaging
Authors: Fallahinia Navid , Harris Sonoma , Mascaro Stephen
Published: November 2018

This paper discusses the grasp force sensing capabilities of the fingernail imaging method integrated with a visual servoing robotic system. The effectiveness of the fingernail imaging method has been demonstrated on the previous works in the prediction of 3-D fingertip forces. In this study, the fingernail imaging method has been modified to be used in constrained grasping studies. Moreover, the technique can be extended to be applied to the unconstrained grasping study as well. Visual servoing has been utilized in this paper to solve the issue of keeping fingernail images in the field of view of the camera during unconstrained grasping motions. The experimental results show the effectiveness of applying visual servoing for use with the fingernail imaging method to be used in grasping studies. Experimental studies were performed on 2 human subjects and the mean value of RMS errors for predicted normal forces during grasping has been found as 0.57 N. (5.7% for the range of 0–10 N)
Design and Control of a Hexacopter With Soft Grasper for Autonomous Object Detection and Grasping
Authors: Mishra Shatadal , Yang Dangli , Thalman Carly , Polygerinos Panagiotis , Zhang Wenlong
Published: November 2018

In this paper, an image based visual servo (IBVS) scheme is developed for a hexacopter, equipped with a robotic soft grasper to perform autonomous object detection and grasping. The structural design of the hexacopter-soft grasper system is analyzed to study the soft grasper’s influence on the multirotor’s aerodynamics. The object detection, tracking and trajectory planning are implemented on a high-level computer which sends position and velocity setpoints to the flight controller. A soft robotic grasper is mounted on the UAV to enable the collection of various contaminants. The use of soft robotics removes excess weight associated with traditional rigid graspers, as well as simplifies the controls of the grasping mechanics. Collected experimental results demonstrate autonomous object detection, tracking and grasping. This pipeline would enable the system to autonomously collect solid and liquid contaminants in water canal based on GPS and multi-camera system. It can also be used for more complex aerial manipulation including in-flight grasping.
Stiffness Control of Parallel Continuum Robots
Authors: Aloi Vincent , Black Caroline , Rucker Caleb
Published: November 2018

Parallel continuum robots can provide compact, compliant manipulation of tools in robotic surgery and larger-scale human robot interaction. In this paper we address stiffness control of parallel continuum robots using a general nonlinear kinetostatic modeling framework based on Cosserat rods. We use a model formulation that estimates the applied end-effector force and pose using actuator force measurements. An integral control approach then modifies the commanded target position based on the desired stiffness behavior and the estimated force and position. We then use low-level position control of the actuators to achieve the modified target position. Experimental results show that after calibration of a single model parameter, the proposed approach achieves accurate stiffness control in various directions and poses.
Comparison Between Position and Rate Control Using a Foot Interface
Authors: Dougherty Zachary J. , Winck Ryder C.
Published: November 2018

There has been a recent increase in research related to supernumerary robotic arms. A challenge with supernumerary robotic arms is how to operate them effectively. One solution is to use the foot to teleoperate the arm. That frees the person to use their arms for other tasks. However, unlike hand interfaces, it is not known how to create effective foot control for robotic teleoperation. This paper presents an experiment to compare position and rate control methods for foot interfaces. A foot interface is presented that can be used for both position and rate control. A human subject experiment uses 2D positioning tasks to evaluate the effectiveness of each control method. These same tasks are tested with a hand interface to provide a baseline for comparison. Results show that, similar to the hand, position control performs faster than rate control when using the foot.
Inter-Area Oscillation Damping in Large-Scale Power Systems Using Decentralized Control
Authors: Biroon Roghieh A. , Pisu Pierluigi , Schoenwald David
Published: November 2018

Inter-area oscillation is one of the main concerns in power system small signal stability. It involves wide area in power system, therefore identifying the causes and damping these oscillations are challenging. Undamped inter-area oscillations may cause severe problems in power systems including large-scale blackouts. Designing a proper controller for power systems also is a challenging problem due to the complexity of the system. Moreover, for a large-scale system it is impractical to collect all system information in one location to design a centralized controller. Decentralized controller will be more desirable for large scale systems to minimize the inter area oscillations by using local information. In this paper, we consider a large-scale power system consisting of three areas. After decomposing the system into three subsystems, each subsystem is modeled with a lower order system. Finally, a decentralized controller is designed for each subsystem to maintain the large-scale system frequency at the desired level even in the presence of disturbances.
State and Output Estimations for a Class of Nonlinear Dynamic Systems With Highly Cross-Sensitive Output Measurements
Authors: Childress Brandon , Chen Pingen
Published: November 2018

While various industries heavily rely on electrochemical sensors for air and liquid quality monitoring and control, many electrochemical sensors are cross-sensitive to one or more interfering gases in addition to the target component, which may cause incorrect readings and lead to improper control measures. In this study, we proposed a direct algebraic approach-based state estimation and output decomposition algorithm which is suitable for state estimation for a class of nonlinear dynamic systems with output measurements that are highly cross-sensitive to multiple interfering gases. Using the cross-sensitive sensor measurement and its successive time derivatives, the proposed methodology can provide a closed-form solution for the actual system state estimation in a systematic way. The established state estimation algorithm was successfully validated in a numeric example. The proposed state estimation and output decomposition algorithm is applicable to a broad class of nonlinear dynamic systems which use sensors that are cross-sensitive to multiple interfering gases in order to improve the performance of the systems.
Adaptive Robust Control of a 7-DoFs Teleoperation Robot System With Payload Variations and Disturbances
Authors: Hu Jinfei , Chen Zheng , Yuan Mingxing , Yao Bin
Published: November 2018

To perform complicated tasks in the unstructured environment, teleoperation robot systems integrating human operators in the control loop have been investigated by researchers recently. Currently, most of the existing researches on the teleoperation robot systems focus on stability-guaranteed issues in the presence of time delays existing in the communication channel between the master and slave site. However, the high accurate performance-oriented motion tracking in the slave site is still a challenging issue due to the following facts: with the coupling dynamics existing in the joints, the dynamics of the slave robot behaves complexly significantly when the degree of freedoms (DoFs) increase, which makes the model compensation extremely difficult in the controller design. Next, parameters variations such as payload changes and effects of modeling errors exist in the actual dynamics of the slave robot manipulator. In this paper, to achieve a high accurate motion tracking performance in the slave site, a teleoperation robot system is configured in which the slave robot is a Baxter manipulator with 7 DoFs. The complicated dynamic model of the Baxter manipulator with 7 DoFs is first established and then further formulated in a linear parametric form for the purpose of online parameter adaptations. In this way, an adaptive robust control (ARC) strategy is developed to deal with the payload variations and modelling errors effectively. The simulation results on the configured teleoperation robot systems indicate that a higher accurate motion tracking performance can be achieved by the developed ARC controller in the presence of payload variations and modelling uncertainties in the Baxter manipulator with 7 DoFs.
Trust-Based Impedance Control Strategy for Human-Robot Cooperative Manipulation
Authors: Sadrfaridpour Behzad , Mahani Maziar Fooladi , Liao Zhanrui , Wang Yue
Published: November 2018

A trust-based switching impedance control strategy for human-robot cooperative manipulation is proposed. The robot behavior switches between the proactive and reactive modes based on the estimated trust of human in robot. The robot estimates the human desired trajectory. A history-based probabilistic trust model for human-robot cooperative manipulation tasks is proposed. Trust is modeled as a dynamic Bayesian network. In the proactive mode, the robot estimates the human desired trajectory and plans accordingly while in the reactive mode, the robot only reacts to the human input. A simulation of the trust-based switching impedance control strategy is presented.
Modeling and Control of Dynamic Cellular Mechanotransduction: Part I — Actin Cytoskeleton Quantification
Authors: Liu Yi , Ren Juan
Published: November 2018

Living cells respond to external stimuli through the reorganization of the actin cytoskeleton, and the actin cytoskeleton significantly affects the cellular mechanical behavior. However, due to the lack of approaches to actin cytoskeleton quantification, the dynamics of mechanotransduction is still poorly understood. In this study, we propose an image recognition-based quantification (IRQ) approach to actin cytoskeleton quantification. IRQ quantifies the actin cytoskeleton through three parameters: the partial actin-cytoskeletal deviation (PAD), the total actin-cytoskeletal deviation (TAD) and the average actin-cytoskeletal intensity (AAI). First, Canny and Sobel edge detectors are applied to skeletonize the actin cytoskeleton images, then PAD and TAD are quantified using the direction of lines detected by Hough transform, and AAI is calculated through the summational brightness over the detected cell area. For validation, six different actin cytoskeleton meshwork models were generated to verify the quantification accuracy of IRQ. The average error for both the quantified PAD and TAD was less than 1.22°. Then IRQ was implemented to quantify the actin cytoskeleton of NIH/3T3 cells treated with an F-actin inhibitor. The quantification results suggest that the local and total actin-cytoskeletal organization of treated cells were more disordered than untreated cells, and the quantity of the actin cytoskeleton decreased significantly after the F-actin treatment.
Development of Magnetic Adhesion Based Wheel-Driven Climbing Machine for Ferrous Surface Applications
Authors: Bisht Ravindra Singh , Pathak Pushparaj Mani , Panigrahi Saroj Kumar
Published: November 2018

This paper presents an autonomous magnetic wheel-driven climbing robot for automatic inspection of above ground steel storage structures, particularly for large even vertical surfaces of above ground tall steel structures. The design, simulation and experimental investigations on a multi-layer permanent magnetic wheel mechanism are discussed. A Finite element model for magneto-static (FEMM) analysis is proposed for an optimal wheel mechanism design. Laboratory experiments have been performed to measure adhesion force generated by the developed magnetic wheel mechanism and compared with simulation results obtained by proposed finite element model. The effect of rubber grip thickness on magnetic wheel for measuring adhesion force is also studied. The coefficient of friction, which plays a vital role for robot locomotion, has been measured experimentally. It should be enough to provide sufficient traction by providing an extra rubber grip added around to the wheel rim. Analysis of forces due to magnetic wheel adhesion mechanism has been made for avoiding climbing robot slipping and toppling while crawling on vertical/incline wall. The wireless communication and control system for prototype climbing robot has been developed using ATMega microcontroller based Arduino boards, motor driver IC, XBee transceiver. The developed autonomous four-wheel differential drive magnetic climbing robot can be controlled remotely from a ground station up to 90 m outdoor line-of-sight working range. The prototype-climbing robot has demonstrated various maneuverability trials on a vertical ferrous surface, and described in this paper.
Experimental Investigation and Analysis of Auto-Ignition Combustion Dynamics
Authors: Tripathi Abhinav , Zhang Chen , Sun Zongxuan
Published: November 2018

From engine controls’ perspective, understanding autoignition dynamics is a key to enabling new combustion modes for internal combustion engines, especially for renewable fuels. Conventional autoignition investigations of fuels commonly involve a rapid compression of oxidizer-fuel mixture to a desired set of temperature-pressure conditions in a rapid compression machine (RCM), and subsequent measurement of the ignition delay. However, even for relatively close thermal states at the compressed condition, different thermodynamic paths (pressure-temperature histories) may lead to significantly different chemical kinetic states and hence significantly different ignition delay measurements. Currently, there exists no systematic method to study this path dependence of auto-ignition.

In this work we present, for the first time, a systematic framework for investigation of the effect of small perturbations in the thermo-kinetic states, caused by perturbing the thermodynamic path of compression, on the ignition delay of fuels from a dynamical systems perspective. First, we introduce a novel controlled trajectory rapid compression and expansion machine (CT-RCEM) which offers the ability to precisely control the piston trajectory during compression of the fuel-oxidizer mixture, allowing the thermodynamic path to be tailored as desired. We use the CT-RCEM to experimentally investigate the influence of compression trajectory perturbation on the ignition delay of a specific fuel — dimethyl-ether (DME). Next, using a reduced order model of the combustion dynamics in the CT-RCEM that we developed, we investigate the evolution of the perturbation in the thermo-kinetic states resulting from trajectory perturbation to explain the experimental observations. Finally, we show that the sensitivity of auto-ignition to the thermodynamic path perturbation essentially arises from changes in the chemical reaction rates due to different amounts of intermediate species buildup for different thermodynamic paths.
On the Vibration Suppression and Energy Harvesting of Building Structures Using an Electromagnetic-Inerter-Absorber
Authors: Joubaneh Eshagh F. , Barry Oumar R. , Zuo Lei
Published: November 2018

This paper studies the performance of an electromagnetic resonant shunt tuned mass-damper-inerter (ERS-TMDI) in terms of simultaneously suppressing unwanted vibration and harvesting energy in a vibrating building. The ERS-TMDI is attached to a building, which is subjected to an earthquake excitation. An inerter is connected between the TMD and the ground. The electromagnetic transducer and associated circuit, which replaces the viscous damping in the classical tuned mas-damper (TMD), is assumed to be an ideal transducer shunted with a resistor, an inductor, and a capacitor (RLC) circuit. Two RLC circuit configurations are investigated: one in series and another in parallel. The governing equations of motion are presented and H2 optimization technique is employed to derive explicit expressions for the optimal mechanical tuning ratio, electrical damping ratio, electrical tuning ratio, and electromagnetic mechanical coupling coefficient. The validity of the obtained closed-form expressions is examined using Matlab optimization toolbox. Parametric studies are carried out to investigate the effect of the mass and inertance ratios on the obtained optimal parameters. Numerical examples are also conducted to demonstrate the role of key design variables on vibration mitigation and energy harvesting performances. Also, the performance of a parallel RLC circuit configuration is compared to that of a series configuration.
Characterizing Combustion Instability Using Deep Convolutional Neural Network
Authors: Gangopadhyay Tryambak , Locurto Anthony , Boor Paige , Michael James B. , Sarkar Soumik
Published: November 2018

Detecting the transition to an impending instability is important to initiate effective control in a combustion system. As one of the early applications of characterizing thermoacoustic instability using Deep Neural Networks, we train our proposed deep convolutional neural network (CNN) model on sequential image frames extracted from hi-speed flame videos by inducing instability in the system following a particular protocol — varying the acoustic length. We leverage the sound pressure data to define a non-dimensional instability measure used for applying an inexpensive but noisy labeling technique to train our supervised 2D CNN model. We attempt to detect the onset of instability in a transient dataset where instability is induced by a different protocol. With the continuous variation of the control parameter, we can successfully detect the critical transition to a state of high combustion instability demonstrating the robustness of our proposed detection framework, which is independent of the combustion inducing protocol.
Optimal Linear-Quadratic Integral Feedback Controller Design With Disturbance Rejection for Proton Exchange Membrane Fuel Cell
Authors: Milanovic Milos , Radisavljevic-Gajic Verica
Published: November 2018

This paper presents, a novel controller design technique that can be used for the Proton Exchange Membrane Fuel Cell to tackle the impact of the sudden stack current disturbances. The proposed controller design consists of three components: a full-state feedback control loop, an integral of error control loop and a feed-forward control loop. The feed-forward control loop is designed to ease the impact of the piecewise continuous current disturbance on the stack voltage. Linearized system matrices are set up in such a way that a new augmented system is formed. Controller gains are calculated by using a quadratic performance criterion which is minimized along the trajectories of the augmented system. Simulation results are presented and discussed.
Negative Obstacle Detection Using LiDAR Sensors for a Robotic Wheelchair
Authors: Baum Taylor E. , Wolkowicz Kelilah L. , Chobot Joseph P. , Brennan Sean N.
Published: November 2018

The objective of this work is to develop a negative obstacle detection algorithm for a robotic wheelchair. Negative obstacles — depressions in the surrounding terrain including descending stairwells, and curb drop-offs — present highly dangerous navigation scenarios because they exhibit wide characteristic variability, are perceptible only at close distances, and are difficult to detect at normal operating speeds. Negative obstacle detection on robotic wheelchairs could greatly increase the safety of the devices.

The approach presented in this paper uses measurements from a single-scan laser range-finder and a microprocessor to detect negative obstacles. A real-time algorithm was developed that monitors time-varying changes in the measured distances and functions through the assumption that sharp increases in this monitored value represented a detected negative obstacle.

It was found that LiDAR sensors with slight beam divergence and significant error produced impressive obstacle detection accuracy, detecting controlled examples of negative obstacles with 88% accuracy for 6 cm obstacles and above on a robotic development platform and 90% accuracy for 7.5 cm obstacles and above on a robotic wheelchair. The implementation of this algorithm could prevent life-changing injuries to robotic wheelchair users caused by negative obstacles.
Stabilization of Traffic Flow With a Leading Autonomous Vehicle
Authors: Yu Huan , Koga Shumon , Krstic Miroslav
Published: November 2018

This paper develops boundary control law for autonomous vehicles to stabilize the stop-and-go traffic on freeway. The macroscopic traffic dynamics is described by the Aw-Rascle-Zhang (ARZ) model in a time and state dependent domain. The leading autonomous vehicle aims to regulate the traffic behind it to uniform equilibrium and the domain length of the traffic to a setpoint. The traffic density and speed is governed by second-order, nonlinear hyperbolic partial differential equations (PDEs), coupled with a state-dependent ODE for the leading autonomous vehicle. The actuation is the speed of autonomous vehicle at the moving front boundary of the domain. We linearize the system around a uniform velocity and density reference and certain physical properties are discussed for the model validity. The linearized model describes the dynamics of deviations of density and velocity from the reference. By transforming the linearized system in a moving coordinate, we obtain a domain with a fixed boundary at one end and a state-dependent moving boundary at the other end. The well-posedness of the system is proved and the linear instability of open-loop system is shown. We further map the system to Riemann variables and based on it, propose the boundary feedback control law actuated by the leading autonomous vehicle. The exponential stability of state variables in L2 norm and convergence to the setpoint domain length is achieved for the closed-loop system.
Composition analysis of Ta3N5/W18O49 nanocomposite through XPS
Authors: Jones Daniel R. , Warwick Michael E. A. , McGettrick James D. , Dunnill Charles W.
Published: November 2018

A characterization of a nanocomposite material consisting of Ta3N5 nanoparticles and W18O49 nanowires is presented. The material is of interest for photocatalytic applications, with a focus on pollution reduction through the photodegradation of dye waste; under white light illumination, the combination of Ta3N5 and W18O49 yielded an enhanced rate of dye degradation relative to Ta3N5 particles alone. The facile method of synthesis is thought to be a promising route for both upscale and commercial utilization of the material. X-ray photoelectron spectroscopy revealed a core–shell composite structure with W18O49 present as an overlayer on Ta3N5; the analyzed spectra for the C 1s, O 1s, Ta 4f, N 1s, W 4f, and Na 1s regions are reported. It should be noted that due to differential charging of the underlying Ta3N5 component relative to the W18O49 shell, an additional uncompensated voltage shift may exist in the Ta 4f and N 1s spectra.
Entanglement signatures of emergent Dirac fermions: Kagome spin liquid and quantum criticality
Authors: Zhu Wei , Chen Xiao , He Yin-Chen , Witczak-Krempa William
Published: November 2018

Quantum entanglement reveals fingerprints of emergent Dirac fermions in the novel spin liquid state on the kagome lattice.
Introduction of Glyoxylate Bypass Increases Hydrogen Gas Yield from Acetate and
l
-Glutamate in
Rhodobacter sphaeroides
Authors: Shimizu Tetsu , Teramoto Haruhiko , Inui Masayuki
Published: November 2018

As an alternative to fossil fuel, H
2
is a promising renewable energy source. Although photofermentative H
2
production from acetate is key to developing an efficient process of biohydrogen production from biomass-derived sugars, H
2
yields from acetate and
l
-glutamate by
R. sphaeroides
have been reported to be low. In this study, we observed that in addition to the endogenous EMC pathway, heterologous expression of the glyoxylate bypass in
R. sphaeroides
markedly increased H
2
yields from acetate and
l
-glutamate. Therefore, this study provides a novel strategy for improving H
2
yields from acetate in the presence of
l
-glutamate and contributes to a clear understanding of acetate metabolism in
R. sphaeroides
during photofermentative H
2
production.
A Small Regulatory RNA Controls Cell Wall Biosynthesis and Antibiotic Resistance
Authors: Borgmann Jessica , Schäkermann Sina , Bandow Julia Elisabeth , Narberhaus Franz
Published: November 2018

The alphaproteobacterium
Agrobacterium tumefaciens
is able to infect various eudicots causing crown gall tumor formation. Based on its unique ability of interkingdom gene transfer,
Agrobacterium
serves as a crucial biotechnological tool for genetic manipulation of plant cells. The presence of hundreds of putative sRNAs in this organism suggests a considerable impact of riboregulation on
A. tumefaciens
physiology. Here, we characterized the biological function of the sRNA PmaR that controls various processes crucial for growth, motility, and virulence. Among the genes directly targeted by PmaR is
ampC
coding for a beta-lactamase that confers ampicillin resistance, suggesting that the sRNA is crucial for fitness in the competitive microbial composition of the rhizosphere.
Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas
Authors: Campbell Matthew A. , Łukasik Piotr , Meyer Mariah C. , Buckner Mark , Simon Chris , Veloso Claudio , Michalik Anna , McCutcheon John P.
Published: November 2018

Sap-feeding insects critically rely on one or more bacteria or fungi to provide essential nutrients that are not available at sufficient levels in their diets. These microbes are passed between insect generations when the mother places a small packet of microbes into each of her eggs before it is laid. We have previously described an unusual lineage fragmentation process in a nutritional endosymbiotic bacterium of cicadas called
Hodgkinia
. In some cicadas, a single
Hodgkinia
lineage has split into numerous related lineages, each performing a subset of original function and therefore each required for normal host function. Here we test how this splitting process affects symbiont transmission to eggs. We find that cicadas dramatically increase the titer of
Hodgkinia
cells passed to each egg in response to lineage fragmentation, and we hypothesize that this increase in bacterial cell count is one of the major costs associated with endosymbiont fragmentation.
Evaluating the Information Content of Shallow Shotgun Metagenomics
Authors: Hillmann Benjamin , Al-Ghalith Gabriel A. , Shields-Cutler Robin R. , Zhu Qiyun , Gohl Daryl M. , Beckman Kenneth B. , Knight Rob , Knights Dan
Published: November 2018

A common refrain in recent microbiome-related academic meetings is that the field needs to move away from broad taxonomic surveys using 16S sequencing and toward more powerful longitudinal studies using shotgun sequencing. However, performing deep shotgun sequencing in large longitudinal studies remains prohibitively expensive for all but the most well-funded research labs and consortia, which leads many researchers to choose 16S sequencing for large studies, followed by deep shotgun sequencing on a subset of targeted samples. Here, we show that shallow- or moderate-depth shotgun sequencing may be used by researchers to obtain species-level taxonomic and functional data at approximately the same cost as amplicon sequencing. While shallow shotgun sequencing is not intended to replace deep shotgun sequencing for strain-level characterization, we recommend that microbiome scientists consider using shallow shotgun sequencing instead of 16S sequencing for large-scale human microbiome studies.
Reevaluating the Salty Divide: Phylogenetic Specificity of Transitions between Marine and Freshwater Systems
Authors: Paver Sara F. , Muratore Daniel , Newton Ryan J. , Coleman Maureen L.
Published: November 2018

The distribution of microbial diversity across environments yields insight into processes that create and maintain this diversity as well as potential to infer how communities will respond to future environmental changes. We integrated data sets from dozens of freshwater lake and marine samples to compare diversity across open water habitats differing in salinity. Our novel combination of sequence-based approaches revealed lineages that likely experienced a recent transition across habitat types. These taxa are promising targets for studying physiological constraints on salinity tolerance. Our findings contribute to understanding the ecological and evolutionary controls on microbial distributions, and open up new questions regarding the plasticity and adaptability of particular lineages.
Secretory cervical schwannoma: first of its kind
Authors: Singh Anup , Chirom Amit Singh , Mathur Sandeep R , Sharma Suresh Chandra
Published: November 2018

Schwannomas arising from cervical sympathetic chain are rare benign neoplasms which are slow growing, usually asymptomatic, biochemically non-secretory and functionally inactive tumours. We present a case of secretory schwannoma arising from the cervical sympathetic chain, causing hypertension and associated with raised urinary catecholamine degradation by-products. Transcervical excision of the tumour was followed by normalisation of blood pressure and urinary vanillylmandelic acid levels and pathologically the tumour was proved to be a schwannoma.
Bilateral central retinal artery occlusion from catastrophic antiphospholipid syndrome
Authors: Joshi Udit , Afroz Sana , Ranka Sagar , Mba Benjamin
Published: November 2018

A 23-year-old woman with history of systemic lupus erythematous presented with dizziness and headache and was admitted for the stroke workup. During her stay, she had sudden painless loss of vision in her right eye consistent with central retinal artery occlusion (CRAO). Ocular massage and paracentesis were attempted without success to resume the flow. She was started on oral high-dose steroids (1 mg/kg) for lupus flare and therapeutic anticoagulation for antiphospholipid syndrome (positive for anticardiolipin and beta-2 microglobulin antibodies). On day 4, she started having painful bluish discoloration of her left index finger and right fifth toe, and on day 5 she had acute onset of left blurry vision with findings consistent with CRAO. She fulfilled the criteria of catastrophic antiphospholipid syndrome and was started on intravenous pulse steroids, plasmapheresis and higher international normalised ratio goal of 3–3.5 with improvement in her left eye vision from 20/200 to 20/20 on near card test by the end of treatment.
Living with disabling chronic pain: results from a face-to-face cross-sectional population-based study
Authors: Cabrera-León Andrés , Cantero-Braojos Miguel Ángel , Garcia-Fernandez Llenalia , Guerra de Hoyos Juan Antonio
Published: November 2018

Objectives

To estimate the prevalence of disabling chronic pain (DCP) in Spanish adults, to analyse its characteristics, to determine its multimorbidity and to identify its associated factors.

Settings

2011 Andalusian Health Survey, a cross-sectional population survey based on face-to-face home interviews.

Participants

6507 people aged 16 years or older and living in Andalusia, Spain.

Outcomes

The response variable was disabling chronic pain. Multivariate multinomial logistic regression models were used to analyse the association of factors with disabling chronic pain. The sample design was considered throughout the statistical analysis.

Results

The prevalence of disabling chronic pain in the Spanish adult population was 11.36% (95% CI 11.23 to 11.49), while that of non-disabling chronic pain was 5.67% (95% CI 5.57 to 5.77). Disabling chronic pain was associated with high multimorbidity (especially in women (51%) and in the elderly (70%) with three or more additional chronic diseases), as well as with disadvantaged social status (such as female gender (OR=2.12), advanced age (OR10-year increase=1.28), unemployment (OR=1.33), manual work (OR=1.26), low income (OR=1.14) and reduced emotional social support (OR=1.04)). Other influential factors were tobacco consumption (OR=1.42), sleeping ≤7 hours (OR=1.2)], environmental or work conditions (OR=1.16) and quality of life (ORmental=1.21, ORphysical=2.37).

Conclusions

The population with disabling chronic pain was associated with multimorbidity, vulnerable social status and an impaired quality of life. In contrast, the population with non-disabling chronic pain showed almost no differences when compared with the population without chronic pain. The association between DCP and mental disorders highlights the need for psychosocial services in the management of chronic pain.
Quality improvement collaborative aiming for Proactive HEAlthcare of Older People in Care Homes (PEACH): a realist evaluation protocol
Authors: Devi Reena , Meyer Julienne , Banerjee Jay , Goodman Claire , Gladman John Raymond Fletcher , Dening Tom , Chadborn Neil , Hinsliff-Smith Kathryn , Long Annabelle , Usman Adeela , Housley Gemma , Bowman Clive , Martin Finbarr , Logan Phillipa , Lewis Sarah , Gordon Adam Lee
Published: November 2018

Introduction

This protocol describes a study of a quality improvement collaborative (QIC) to support implementation and delivery of comprehensive geriatric assessment (CGA) in UK care homes. The QIC will be formed of health and social care professionals working in and with care homes and will be supported by clinical, quality improvement and research specialists. QIC participants will receive quality improvement training using the Model for Improvement. An appreciative approach to working with care homes will be encouraged through facilitated shared learning events, quality improvement coaching and assistance with project evaluation.

Methods and analysis

The QIC will be delivered across a range of partnering organisations which plan, deliver and evaluate health services for care home residents in four local areas of one geographical region. A realist evaluation framework will be used to develop a programme theory informing how QICs are thought to work, for whom and in what ways when used to implement and deliver CGA in care homes. Data collection will involve participant observations of the QIC over 18 months, and interviews/focus groups with QIC participants to iteratively define, refine, test or refute the programme theory. Two researchers will analyse field notes, and interview/focus group transcripts, coding data using inductive and deductive analysis. The key findings and linked programme theory will be summarised as context-mechanism-outcome configurations describing what needs to be in place to use QICs to implement service improvements in care homes.

Ethics and dissemination

The study protocol was reviewed by the National Health Service Health Research Authority (London Bromley research ethics committee reference: 205840) and the University of Nottingham (reference: LT07092016) ethics committees. Both determined that the Proactive HEAlthcare of Older People in Care Homes study was a service and quality improvement initiative. Findings will be shared nationally and internationally through conference presentations, publication in peer-reviewed journals, a graphical illustration and a dissemination video.
Quality of outpatient parenteral antimicrobial therapy (OPAT) care from the patient’s perspective: a qualitative study
Authors: Berrevoets Marvin A H , Oerlemans Anke J M , Tromp Mirjam , Kullberg Bart Jan , ten Oever Jaap , Schouten Jeroen A , Hulscher Marlies E
Published: November 2018

Objectives

Current outpatient parenteral antimicrobial therapy (OPAT) guidelines recommend delivering patient-centred care. However, little is known about what patients define as good quality of OPAT care and what their needs and preferences are.

The aim of this qualitative study is to explore the patients’ perspective on high-quality care, and to explore what patient-centred care means to adult OPAT patients.

Design and setting

This is an explorative, descriptive study using qualitative methods. We conducted focus group interviews with 16 adult patients (5 female, 11 male) from 3 different hospitals, who received OPAT and 2 individual semistructured interviews with their informal caregivers in the Netherlands. We used purposive sampling to ensure diversity of participants. We used the eight Picker principles of patient-centredness to guide data collection and analysis.

Results

Participants reported several elements considered as important for patient-centred OPAT care, like patient involvement in the decision-making process, a responsible OPAT lead, intensive collaboration between all disciplines involved, information provision and adherence to hygiene guidelines. Two central dimensions emerged as essential constituents of patient-centred OPAT care: freedom and safety. Both are heavily influenced by the behaviours of healthcare professionals and by organisational aspects beyond the direct influence of these professionals.

Conclusion

This study provides insights into the needs and preferences of adult patients who receive OPAT care. Future interventions directed at the improvement of patient-centredness of OPAT care should focus on elements that enhance patients’ feelings of freedom and safety.
Cost-effectiveness of a care manager collaborative care programme for patients with depression in primary care: economic evaluation of a pragmatic randomised controlled study
Authors: Holst Anna , Ginter Annika , Björkelund Cecilia , Hange Dominique , Petersson Eva-Lisa , Svenningsson Irene , Westman Jeanette , André Malin , Wikberg Carl , Wallin Lars , Möller Christina , Svensson Mikael
Published: November 2018

Objective

To evaluate the cost-effectiveness of a care manager (CM) programme compared with care as usual (CAU) for treatment of depression at primary care centres (PCCs) from a healthcare as well as societal perspective.

Design

Cost-effectiveness analysis.

Setting

23 PCCs in two Swedish regions.

Participants

Patients with depression (n=342).

Main outcome measures

A cost-effectiveness analysis was applied on a cluster randomised trial at PCC level where patients with depression had 3 months of contact with a CM (11 intervention PCCs, n=163) or CAU (12 control PCCs, n=179), with follow-up 3 and 6 months. Effectiveness measures were based on the number of depression-free days (DFDs) calculated from the Montgomery-Åsberg Depression Rating Scale-Self and quality-adjusted life years (QALYs). Results were expressed as the incremental cost-effectiveness ratio: ∆Cost/∆QALY and ∆Cost/∆DFD. Sampling uncertainty was assessed based on non-parametric bootstrapping.

Results

Health benefits were higher in intervention group compared with CAU group: QALYs (0.357 vs 0.333, p<0.001) and DFD reduction of depressive symptom score (79.43 vs 60.14, p<0.001). The mean costs per patient for the 6-month period were €368 (healthcare perspective) and €6217 (societal perspective) for the intervention patients and €246 (healthcare perspective) and €7371 (societal perspective) for the control patients (n.s.). The cost per QALY gained was €6773 (healthcare perspective) and from a societal perspective the CM programme was dominant.

Discussion

The CM programme was associated with a gain in QALYs as well as in DFD, while also being cost saving compared with CAU from a societal perspective. This result is of high relevance for decision-makers on a national level, but it must be observed that a CM programme for depression implies increased costs at the primary care level.

Trial registration number

NCT02378272; Results.
An Asian consensus on standards of diagnostic upper endoscopy for neoplasia
Authors: Chiu Philip Wai Yan , Uedo Noriya , Singh Rajvinder , Gotoda Takuji , Ng Enders Kwok Wai , Yao Kenshi , Ang Tiing Leong , Ho Shiaw Hooi , Kikuchi Daisuke , Yao Fang , Pittayanon Rapat , Goda Kenichi , Lau James Y W , Tajiri Hisao , Inoue Haruhiro
Published: November 2018

Background

This is a consensus developed by a group of expert endoscopists aiming to standardise the preparation, process and endoscopic procedural steps for diagnosis of early upper gastrointestinal (GI) cancers.

Method

The Delphi method was used to develop consensus statements through identification of clinical questions on diagnostic endoscopy. Three consensus meetings were conducted to consolidate the statements and voting. We conducted a systematic literature search on evidence for each statement. The statements were presented in the second consensus meeting and revised according to comments. The final voting was conducted at the third consensus meeting on the level of evidence and agreement.

Results

Risk stratification should be conducted before endoscopy and high risk endoscopic findings should raise an index of suspicion. The presence of premalignant mucosal changes should be documented and use of sedation is recommended to enhance detection of superficial upper GI neoplasms. The use of antispasmodics and mucolytics enhanced visualisation of the upper GI tract, and systematic endoscopic mapping should be conducted to improve detection. Sufficient examination time and structured training on diagnosis improves detection. Image enhanced endoscopy in addition to white light imaging improves detection of superficial upper GI cancer. Magnifying endoscopy with narrow-band imaging is recommended for characterisation of upper GI superficial neoplasms. Endoscopic characterisation can avoid unnecessary biopsy.

Conclusion

This consensus provides guidance for the performance of endoscopic diagnosis and characterisation for early gastric and oesophageal neoplasia based on the evidence. This will enhance the quality of endoscopic diagnosis and improve detection of early upper GI cancers.
Epidemiology of pericardial diseases in Africa: a systematic scoping review
Authors: Noubiap Jean Jacques , Agbor Valirie Ndip , Ndoadoumgue Aude Laetitia , Nkeck Jan René , Kamguia Arnaud , Nyaga Ulrich Flore , Ntsekhe Mpiko
Published: November 2018

Objectives

This scoping review sought to summarise available data on the prevalence, aetiology, diagnosis, treatment and outcome of pericardial disease in Africa.

Methods

We searched PubMed, Scopus and African Journals Online from 1 January 1967 to 30 July 2017 to identify all studies published on the prevalence, aetiologies, diagnosis, treatment and outcomes of pericardial diseases in adults residing in Africa.

Results

36 studies were included. The prevalence of pericardial diseases varies widely according to the population of interest: about 1.1% among people with cardiac complaints, between 3.3% and 6.8% among two large cohorts of patients with heart failure and up to 46.5% in an HIV-infected population with cardiac symptoms. Tuberculosis is the most frequent cause of pericardial diseases in both HIV-uninfected and HIV-infected populations. Patients with tuberculous pericarditis present mostly with effusive pericarditis (79.5%), effusive constrictive pericarditis (15.1%) and myopericarditis (13%); a large proportion of them (up to 20%) present in cardiac tamponade. The aetiological diagnosis of pericardial diseases is challenging in African resource-limited settings, especially for tuberculous pericarditis for which the diagnosis is not definite in many cases. The outcome of these diseases remains poor, with mortality rates between 18% and 25% despite seemingly appropriate treatment approaches. Mortality is highest among patients with tuberculous pericarditis especially those coinfected with HIV.

Conclusion

Pericardial diseases are a significant cause of morbidity and mortality in Africa, especially in HIV-infected individuals. Tuberculosis is the most frequent cause of pericardial diseases, and it is associated with poor outcomes.