bluuebunny/crossref_metadata_2025 huggingface dataset:
Compositing Coexisting Attractors by Linear Augmentation
Authors: Liu Chang , Zeng Yi Cheng
Published: December 2019

In this paper, the composition of coexisting attractors is achieved through the control method of linear augmentation, which can also be considered as a new idea to generate multiscroll attractors. In order to prove the effectiveness, Chua oscillator and classical Lorenz system are taken into consideration. Furthermore, the corresponding electronic circuit is designed based on Lorenz system. The multism simulation results and the hardware experimental results are in agreement with the numerical simulations on the matlab platform, which verifies the feasibility of this control method.
Does Visual Fixation Affect Idea Fixation?
Authors: Kwon E. , Ryan J. D. , Bazylak A. , Shu L. H.
Published: December 2019

Divergent thinking, an aspect of creativity, is often studied by measuring performance on the Alternative Uses Test (AUT). There is, however, a gap in creativity research concerning how visual stimuli on the AUT are perceived. Memory and attention researchers have used eye-tracking studies to reveal insights into how people think and how they perceive visual stimuli. Thus, the current work uses eye tracking to study how eye movements are related to creativity. Participants orally listed alternative uses for twelve objects, each visually presented for 2 min in four different views. Using eye tracking, we specifically explored where and for how long participants fixate their eyes at visual presentations of objects during the AUT. Eye movements before and while naming alternative uses were analyzed. Results revealed that naming new instances and categories of alternative uses correlated more strongly with visual fixation toward multiple views than toward single views of objects. Alternative uses in new, previously unnamed categories were also more likely named following increased visual fixation toward blank space. These and other findings reveal the cognitive-thinking styles and eye-movement behaviors associated with naming new ideas. Such findings may be applied to enhance divergent thinking during design.
A Preference-Based Approach to Assess a Component’s Design Readiness for Additive Manufacturing
Authors: Ghiasian Seyedeh Elaheh , Jaiswal Prakhar , Rai Rahul , Lewis Kemper
Published: December 2019

Due to the benefits associated with additive manufacturing (AM), there are increasingly more opportunities to leverage AM to enable the fabrication of components that were previously made using conventional techniques such as subtractive manufacturing or casting. To support this transition, it is critical to be able to rigorously evaluate the technical and economic feasibility of additively manufacturing an existing component design. In order to support this evaluation, this paper presents a novel feasibility analysis that performs a multi-criteria assessment of AM readiness. Along with the development of these assessments, we also present a novel scoring approach for qualitatively and quantitatively evaluating the feasibility of each component assessment. This scoring approach, which leverages preference models from physical programing, introduces a flexible set of feasibility levels to assess the manufacturability capabilities of AM technologies. It also allows for the integration of a designer’s preferences toward the AM assessments, supporting the decision whether to utilize AM technologies or not. The presented feasibility analysis allows for both technical and economic benefits since it suggests only using AM for those products whose feasibility results are within suitable ranges. The details of the approach are illustrated using four sample parts with varying geometries. Experimental validation is also performed to demonstrate the robustness of the evaluation. Results obtained show the capability and generalizability of these approaches to analyze intricate geometries and provide useful decision support in AM feasibility analysis.
Investigation of the Lifetime of Antagonistic Shape Memory Wires With Focus on Accelerated Resetting
Authors: Weirich Antonia , Theren Benedict , Otibar Dennis , Kuhlenkötter Bernd
Published: December 2019

The antagonistic setup of shape memory actuators enables a multitude of further applications than designs with only one shape memory element. In these actuators, two opposed shape memory elements work against each other and also ensure mutual resetting. This setup allows easily controlled and powersaving actuators for applications with two end positions such as locks or latches. It not only eliminates mechanical resetting, for example by a spring, but also offers a simple realization of holding the end positions energy-free and thereby conserving the shape memory effect.

In order to maximize the potential of this actuator design, the authors investigate the interdependencies between antagonistic wires. This paper focuses on the effect of resetting a previously activated NiTi wire by another, similar antagonistic wire before it cooled down completely. On the one hand, very early resetting can have a negative effect on both the cooling and especially the activated wire. This is mainly noticeable in a shortened lifetime of the actuator elements. On the other hand, applying mechanical strain by activating the opposed wire can accelerate phase transformation within the cooling wire. The authors performed corresponding fatigue tests with different cooling times in the antagonistic setup, in order to narrow down a timeframe for the optimized usability of an antagonistic wire actuator.
Investigation of the Fatigue Strength of Shape Memory Wires With Different Diameters
Authors: Otibar Dennis , Theren Benedict , Weirich Antonia , Kuhlenkötter Bernd , Tung Haang Wai
Published: December 2019

The properties of shape memory alloy wires (SMA wires) have still not been sufficiently investigated, which is the reason why shape memory-based actuators can hardly be found in serial or commercial applications in industry. The most important parameter for industrial applications is the fatigue strength of SMA wires under cyclic activation with mechanical stress. So far only isolated and application-specific investigations have been carried out. Thus there are no reliable statements on fatigue strength or reliable design calculations for design and application. Among other things, this circumstance is considered to be the reason why the majority of companies is still not ready or willing to use SMA technology in series production. This paper deals with a series of tests to determine the fatigue life of shape memory wires of different diameters by means of the design of experiments. Primarily the results aim at making more reliable predictions about the fatigue strength of shape memory wires, which are subject to statistical safety. Besides, the focus is on the influence of the wire diameter on the fatigue strength. The interdependency parameters are strain, stress and wire diameter. The fatigue strengths are shown in standardized Wohler diagrams, which should serve as a basis for future fatigue tests of shape memory wires. The main influence on the fatigue strength is the strain as expected. Another interesting tendency can be seen in the dependence on the wire diameter. Thus, this paper makes a contribution to the further application of this technology in both industrial and scientific environments.
On the Design of a Long-Stroke Beam-Based Compliant Mechanism Providing Quasi-Constant Force
Authors: Bilancia Pietro , Geraci Alessandro , Berselli Giovanni
Published: December 2019

In this paper the design of a linear long-stroke quasi-constant force compliant mechanism (CM) is presented and discussed. Starting from a flexure-based slider-crank mechanism, providing the required constant force within a rather limited deflection range, the paper reports about the shape optimization carried out with the specific aim of extending the available CM operative range. The proposed device is suitable in several precision manipulation systems, which require to maintain a constant-force at their contact interface with the manipulated object. Force regulation is generally achieved by means of complex control algorithms and related sensory apparatus, resulting in a flexible behavior but also in high costs. A valid alternative may be the use of a purposely designed CM, namely a purely mechanical system whose shape and dimensions are optimized so as to provide a force-deflection behavior characterized by zero stiffness. In the first design step, the Pseudo-Rigid Body (PRB) method is exploited to synthesize the sub-optimal compliant configuration, i.e. the one characterized by lumped compliance. Secondly, an improved design alternative is evaluated resorting to an integrated software framework, comprising Matlab and ANSYS APDL, and capable of performing non-linear structural optimizations. The new embodiment makes use of a variable thickness beam, whose shape and dimensions have been optimized so as to provide a constant reaction force in an extended range. Finally, a physical prototype of the beam-based configuration is produced and tested, experimentally validating the proposed design method.
Finite Element-Based Numerical Investigations of a Beamlike Actuator Combining Shape Memory and Superelastic Effects
Authors: Reis Danillo C. , Rade Domingos A. , Santos Osmar S.
Published: December 2019

It has been amply demonstrated that the development of SMA actuators has a great potential of application in several branches of industry. Obviously, the efficiency of the actuators depends both on the inherent features of the materials they are made of and the geometric characteristics of the devices. This work considers a particular type of actuator first conceived by [1], consisting in the association of two cantilever beams, the first presenting the shape memory effect and the second presenting the superelastic effect, coupled mechanically so as to guarantee two equilibrium positions and thus a stand-alone cyclic actuator, in which the superelastic beam provides the bias action. Numerical simulations of the behavior of the actuator are performed using the commercial finite element software COMSOL, which implements the Boyd-Lagoudas thermomechanical model. The goal of the simulations is to characterize the actuation range of the actuator, in terms of maximum displacement obtained at the tip. The effect of the dimensions of the beams on the tip displacement under some load scenarios is investigated. The results provide guidelines for the design of the actuator to fulfill specific requirements, also suggesting the use of numerical optimization for the optimal design of the actuator accounting for constraints.
Control of Brake Squeal Using Shunted Piezoelectric Pads
Authors: Abdullah Yaqoub , Baz Amr
Published: December 2019

Brake squeal phenomenon poses serious challenges to the automotive industry due to its technical complexity and the pressing need for mitigating its undesirable effects. More importantly, brake squeal causes significant customer dissatisfaction and adversely affects the subjective quality of the vehicles. These effects have substantial economic impact on the automotive industry. Furthermore, it is essential to properly treat the brake squeal problems in order to avoid unexpected catastrophic failure of the brake system.

In this paper, it is proposed to mitigate the brake squeal problems by providing the brake pads with piezoelectric patches which are shunted by properly tuned electric networks. The shunted piezoelectric pads offer a unique ability to convert the mechanical energy induced by the brake squeal into electrical energy which can be dissipated into the network in order to enhance the damping and stability characteristics of the brake system. Accordingly, it is envisioned that the proposed approach would enable the disc brake systems to operate over broad ranges of operating parameters without experiencing the adverse effects of brake squeal.

The proposed system is modeled by a simple two Degree-Of-Freedom (DOF) disc brake model. The structural DOF are integrated with the constitutive model of the shunted piezoelectric network in order to predict the threshold of brake squeal. The stability limits of the proposed brake system are established as a function of the design parameters of the shunted piezoelectric network. Numerical examples are presented to demonstrate the effectiveness of the proposed system in expanding the operating range of the brake system without experiencing squeal problems.

Application of the proposed system to a distributed disc brake system model is a natural extension of the present work.
A Three-Row Opposed Gripping Mechanism With Radial Configuration for Wall-Climbing Robots
Authors: Xie Chao , Wu Xuan , Wang Xiaojie
Published: December 2019

This paper presents a three-row opposed gripping mechanism with radial configuration for wall-climbing robots inspired by the structure of the gripper of LEMUR IIB. The mechanism builds upon a kind of microspines for climbing robots. This work utilizes an opposed spoke configuration with 3 rows of 31 microspines on each linkage array, splayed around a central bracket. A single motor drives the 3 linkage arrays by a set of gears to achieve attachment and detachment procedures, and the trajectory of each linkage array tip makes the miniature spines easy to penetrate in and pull off the surfaces. The mechanism designed as a foot of climbing robots can vertically resist at least 1kg of load on rough surface. The findings provide a foundation for constructing a system for a rough-wall-climbing robot.
Active Thermal Management of FRP Composites via Embedded Vascular Networks
Authors: Cole Jim , Bond Ian , Lawrie Andrew
Published: December 2019

Fibre-reinforced polymer (FRP) composite materials are limited in high temperature applications by the matrix glass transition temperature, Tg. At and above this temperature, significant mechanical performance is lost, and degradation processes accelerated. This research explores the use of internal passages, or vascules, within the laminate to carry a coolant fluid, absorbing heat energy and cooling the material. A custom thermal chamber and four-point flexural test fixture were developed to perform in-situ thermo-mechanical testing. Vascular and non-vascular carbon/epoxy specimens were manufactured, containing arrays of four 1.1 mm diameter vascules. Specimens were exposed to temperatures from ambient to 170 °C (Tg = 200 °C). Flexural modulus varied little with temperature across all tests. Non-vascular specimens at 170 °C showed a reduction in ultimate strength of 21 % compared to under ambient conditions. The presence of vascules caused a small improvement in flexural modulus and strength, due to displacement of a small number of 0° fibre tows further from the neutral axis as a result of the manufacturing process. At 15 L·min−1 coolant flow, vascular specimens showed full retention of strength compared to non-vascular specimens at ambient, demonstrating the potential mechanical performance benefits.
DNA Nanotechnologies for the Design of Bio-Inspired Soft Nanocomposites With Reversible Rigidity
Authors: Calais Theo , Stalin Thileepan , Joseph Vincent S. , Valdivia y Alvarado Pablo
Published: December 2019

Structures and mechanisms in soft robotics are primarily based on chemically versatile species such as hydrogels, polymers, or elastomers, thus offering great potential for the design of adaptive core properties. In particular, tunable rigidity is highly desirable to enable control of soft grippers or for advanced robot locomotion. However, most of the strategies explored so far rely on mechanisms, such as phase transitions or shape memory effects, that require heavy external hardware or have a limited range of tunable rigidity.

In this work, we propose a novel strategy inspired by the sea cucumber dermis mechanism. High aspect ratio carbon nanotubes (CNTs) are reversibly interconnected by DNA oligonucleotides within a polyacrylamide (PAAm) hydrogel. The combination of the excellent mechanical properties of CNTs and the reversible hybridization of DNA strands into a stable double-helicoidal structure allowed the reversible tunability of mechanical properties over one order of magnitude (from ∼100 Pa to ∼1 kPa) within minutes by increasing the temperature beyond the melting temperature of DNA strands (∼50 °C). First, the functionalization strategy of CNTs with DNA strands is described and characterized. The aggregation of CNTs driven by the DNA hybridization is then demonstrated. The mechanical properties of hydrogels functionalized with CNTs are finally analyzed using rheology measurements.
A Variable Camber Piezocomposite Trailing-Edge for Subsonic Aircraft: Multidisciplinary Design Optimization
Authors: Wright Cody , Bilgen Onur
Published: December 2019

A continuous-surface morphing airfoil is desirable for commercial aircraft in order to improve fuel efficiency, and due to the potential to morph the wing into a high-lift configuration for take-off and landing. Piezocomposite actuators have shown to be a feasible strategy for camber morphing in small unmanned fixed-wing aircraft with a Reynold’s number in the range of 50,000 to 250,000. As an extension, this paper presents a theoretical framework and results for morphing in single and multi-segment natural laminar flow airfoils with a maximum Reynold’s number of 825,000. The airfoils presented employ a continuous inextensible surface. To achieve morphing, piezocomposite actuating elements are applied on the suction and pressure surfaces of the airfoils. The geometric properties of the airfoils are determined using a genetic algorithm optimization method with a migration strategy in order to maintain population diversity. The algorithm optimizes independently the substrate thicknesses for the nominal airfoil, the leading edge, and the piezocomposite bonded surfaces. In addition, positions and voltages for each piezocomposite actuators are optimized. The genetic algorithm uses an objective function to maximize the change in coefficient of lift to morph the airfoil from its baseline (i.e. cruise) state to the high-lift state. Analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. Optimization is followed by a parametric analysis to examine lift, drag, and lift-to-drag ratio of the airfoils over their full operational range. The optimization is performed on a symmetric, asymmetric, and the aft element of a slotted multi-segment airfoil to examine the capabilities of induced-strain actuation at high dynamic pressures.
Miniaturized Broadband Vibration Energy Harvester With Piecewise-Linear Asymmetric Restoring Force
Authors: Masuda Arata , Zhao Feng
Published: December 2019

This paper presents a design study of a miniaturized broadband nonlinear vibration energy harvester (VEH) with piecewise-linear restoring force based on a mechanically-sprung resonator with stoppers. It is commonly recognized that a VEH based on a nonlinearly-sprung resonator can show broadband frequency characteristics while keeping its maximum power performance due to its bent resonance peak. The resonator to be investigated in this study consists of a magnet composite as a mass moving through an induction coil, two planar springs, and mechanical stoppers. The magnet composite is comprised of two repelling cylindrical magnets and a steel disk between them, all encapsulated in a thin stainless-steel cylinder. The planar springs with spiral-like shape are respectively connected to the both ends of the magnet composite so that they provide soft linear stiffness in a compact size. The mechanical stoppers installed to constrain the deformation of the spring give the resonator piecewise-linear hardening characteristics which effectively broaden the resonance band. In this study, the prototype VEH developed in the previous study is presented, and the gaps between the springs and stoppers are adjusted so that the resultant piecewise-linear restoring force shows symmetric or asymmetric property with respect to the equilibrium point. Experimental studies and analyses are carried out to examine the performance of the presented VEH in terms of the frequency response. The comparison of three different configurations of the stopper illustrates how the asymmetry in the bilinear restoring force affects the shape of the resonance peak. It is also suggested that the asymmetry may help the VEH operate in broader band by exploiting its ability of tailoring the resonance characteristics, which still needs further investigation.
Compact Telescopic Morphing Lattice Boom
Authors: McHale Ciarán , Telford Robert , Weaver Paul M.
Published: December 2019

This paper reports on the design and manufacture of a compact telescopic morphing lattice (CTML) space boom. This boom stows within a 1U CubeSat volume and weighs only 0.475kg. Once deployed, the CTML has a total length of 2m, 20 times the stowed height. The device consists of three multi-stable cylindrical composite lattices connected in series. To improve packaging efficiency, these lattices nest inside one another in the stowed configuration. The morphing lattice is a structure that uses prestress and lamina orientation to seamlessly morph from a short stowed state to a long deployed state. By tailoring the manufacturing parameters, the lattices in the boom have been designed to maximize the deployment force and to be self-deploying. Therefore, the CTML only requires a small, lightweight mechanism to regulate the deployment speed. The deployment speed regulator can also potentially retract the boom back to the stowed state, facilitating reconfigurability.
Target Shape Optimization of 3D Compliant Mechanism With Superelastic Joints and Shape Memory Actuation
Authors: Jovanova Jovana , Nastevska Angela , Frecker Mary
Published: December 2019

The shape memory effect and the superelasticity of nickel titanium (NiTi) alloys are beneficial for design of compliant mechanisms. The superelastic behavior of NiTi can be tailored for optimal flexure design in the compliant mechanism, allowing large deformation and shape change. The shape memory effect can also be utilized to actuate the compliant mechanism flexures enabling programing of the material to take on variety of shapes at different temperatures over time.

The compliant mechanism analyzed in this work is inspired from 3D multi leg spider-like locomotion, enabling movement in all directions by triggering different target shapes in time. The control of the material spatial distribution facilitated by additive manufacturing will enable tailored superelastic and shape memory behavior in the flexures of the multifunctional 3D compliant mechanism.

Design optimization and analyses as well as overall shape change are explored in this work. Superelastic joints are introduced as flexures to enable segment flexibility. The temperature change is used for actuation taking in consideration different initial strain conditions.
Memcapacitive Devices in Neuromorphic Circuits via Polymeric Biomimetic Membranes
Authors: Basham Colin , Pitz Megan , Najem Joseph , Sarles Stephen , Hasan Md Sakib
Published: December 2019

Two-terminal adaptive materials and circuit elements that mimic the signal processing, learning, and computing capabilities of biological synapses are essential for next-generation computing systems. To this end, we have recently developed resistive (ion channel) and capacitive (lipid bilayer) memory elements that mimic the composition, structure, and plasticity of biological synapses. Unlike solid-state counterparts, these biomolecular systems are low-power, analog, less noisy, biocompatible, and capable of exhibiting multiple timescales of short-term synaptic plasticity. However, lipid membranes lack structural stability and modularity necessary for a long-lasting adaptive material system. To address this issue, we propose the replacement of phospholipids with amphiphilic polymers to create artificial membranes, which have been demonstrated to be more durable than phospholipids. With the focus on memory capacitors, we demonstrate that polymeric bilayers can exhibit pinched hysteresis in the Q-v plane because of voltage-induced geometrical changes. Further, we demonstrate that the memcapacitive response is altered based on the surrounding oil medium; smaller oil molecules are retained at higher volume in the membrane, so that thicker bilayers have lower nominal capacitance but can vary this value by over 400%. Finally, we present a physics-based model that enables us to predict the device’s areal voltage-dependent response. Polymeric bilayers represent a significant enhancement in the field of soft-matter, geometrically-reconfigurable memcapacitors, and their highly customizable compositions will allow for a finely tuned electrical response that has a future in brain-inspired materials and circuits.
Nanocomposite Coating for Strain Monitoring
Authors: Magnafico Erika , Poli Francesco , Casalotti Arnaldo , Lanzara Giulia
Published: December 2019

In recent years carbon nanotubes (CNTs) have been widely used for the realization of polymeric matrix nanocomposites for strain monitoring applications in civil, biomedical and aerospace engineering. In fact, by embedding CNTs in an insulated polymer matrix, it is possible to realize a conductive nanocomposite with piezoresistive behaviour which allows to monitor the occurring strains through an electrical resistance change. In this work a conductive coating made of Multi-Walled Carbon Nanotubes (MWNTs) and PolymethylMethacrilate (PMMA) is fabricated and is applied onto a fiberglass structure surface. In order to characterize the electrical behaviour of the coating and its capability to sense strain, an experimental campaign is carried out by applying a voltage to the manufactured coating. Its variations throughout the surface in the longitudinal and transverse directions are then evaluated to identify the electric field distribution and its dependence on strain.
Exfoliated-Graphite/Latex Piezoresistive System for Mapping Plantar Pressure
Authors: Riegel Allison , Gray Jonathan , Zegeye Ephraim F.
Published: December 2019

Diabetics often have neuropathy that prevents them from noticing developing foot ulcers. Pressure sensors can detect areas with abnormally high pressure, allowing earlier detection, prevention, and treatment of developing ulcers. Accurate pressure sensors are often limited to bulky or stationary systems, or have other limitations such as lack of accuracy, slow response times, and cost. This paper explains the fabrication of a prototype system using a bilayer flexible sensor for better accuracy in measuring pressure. The sensor is made of an exfoliated graphite film on a latex substrate and is layered with rubber padding to allow deformation. It is connected to an electronic system that reads changing resistance due to pressure and maps the applied pressure. This system might be a low cost, accurate, and durable alternative to current systems.
Pressure influence on elastic wave attenuation in polycrystalline materials
Authors: Kube Christopher M. , Arguelles Andrea P.
Published: December 2019

Traditionally, the acoustoelastic effect refers to the influence of stress in a solid on an elastic wave's phase velocity. Since the phase velocity can be represented by the real part of the complex wave number, a natural question arises regarding the effect of stress on the imaginary part or dissipation of the wave. In this article, the influence of pressure on the elastic wave's attenuation in polycrystalline materials is modeled. The constitutive behavior of an initially stressed solid is coupled into Weaver's scattering-based attenuation model [J. Mech. Phys. Solids 38, 55–86 (1990)]. As a result, the pressure-dependent longitudinal and shear wave attenuation coefficients are unveiled. As the traditional stress-free attenuation coefficients depend on the degree of single-crystal elastic anisotropy, it is shown that the pressure influence on attenuation depends on the anisotropy of the single-crystal's third-order or nonlinear elastic constants. Analysis of the model indicates linkages between pressure derivatives of velocity and attenuation to the material's linear and nonlinear elastic anisotropy, crystal structure, and type of atomic bonding.
Informing trait-based ecology by assessing remotely sensed functional diversity across a broad tropical temperature gradient
Authors: Durán Sandra M. , Martin Roberta E. , Díaz Sandra , Maitner Brian S. , Malhi Yadvinder , Salinas Norma , Shenkin Alexander , Silman Miles R. , Wieczynski Daniel J. , Asner Gregory P. , Bentley Lisa Patrick , Savage Van M. , Enquist Brian J.
Published: December 2019

Remote sensing of trait-based ecology can improve our understanding of the effect of trait diversity on ecosystem functioning.
The polar regions in a 2°C warmer world
Authors: Post Eric , Alley Richard B. , Christensen Torben R. , Macias-Fauria Marc , Forbes Bruce C. , Gooseff Michael N. , Iler Amy , Kerby Jeffrey T. , Laidre Kristin L. , Mann Michael E. , Olofsson Johan , Stroeve Julienne C. , Ulmer Fran , Virginia Ross A. , Wang Muyin
Published: December 2019

Polar warming will have widespread near-term consequences for sea level rise, extreme weather, plants, animals, and humans.
Novel technique of explantation of rigid phakic iris-claw lens and cataract extraction by sutureless manual small-incision surgery
Authors: Agarwal Prateek , Navon Samuel Edward , Mithal Neha
Published: December 2019

A 38-year-old patient presented to us with complaints of blurred vision and photophobia in the left eye with an uncorrected visual acuity of 20/400, improving to 20/60 with pinhole. The patient underwent phakic iris-claw lens surgery 15 years ago for high myopia. On examination, there was anterior chamber rigid phakic iris-claw lens along with complicated cataract. We planned for sutureless self-sealing 6.5 mm sclerocorneal tunnel for explantation of rigid phakic iris-claw lens along with cataract extraction with irrigating vectis. There was postoperative reduction in astigmatism due to incision planned on steep axis, and visual acuity improved to 20/30 uncorrected. This technique provides significant advantages from the previously described techniques in terms of decreased postop astigmatism, no need for sutures, no issues of chamber instability and iris trauma and without the need for phacoemulsification.
Refractive change in children with accommodative esotropia
Authors: Bonafede Lucas , Bender Lloyd , Shaffer James , Ying Gui-shuang , Binenbaum Gil
Published: December 2019

Objective

To determine whether there is a measurable change in hyperopia in children with accommodative esotropia over time.

Methods and analysis

A retrospective cohort of children with fully or partially accommodative esotropia diagnosed by age 7 years, followed to age 10 or older, and with at least two cycloplegic refractions, one before age 7 years and one after age 10 years. The annual change was calculated from linear mixed-effect models, overall and during two age periods with subgroup analysis by baseline refractive error (<4D, ≥4D) and type (partial, full) of accommodative esotropia.

Results

405 subjects were studied. Mean age at first and last visit was 3.2 and 12.1 years, respectively, with mean 7.6 cycloplegic refractions. The annual change (95% CI) in refractive error was −0.071 (−0.087 to –0.055) D/yr. Between ages 3 and 7, hyperopia among children with baseline hyperopia <4D increased by 0.12 (0.08 to 0.16) D/yr, while hyperopia among those with baseline 4D or greater was stable (0.0D/yr, −0.03 to 0.04) (p<0.001). Hyperopia decreased from age 7 to 15 years in both subgroups: <4D subgroup −0.17 (−0.20 to –0.14) D/yr, ≥4D subgroup −0.18 (−0.21 to –0.15) D/yr (p=0.58). There was no significant difference in refractive change between fully (n=274) and partially (n=131) accommodative esotropia (p≥0.10).

Conclusion

Hyperopia in children with accommodative esotropia is stable or increases up to age 7 years, depending on baseline hyperopia, but decreases gradually between ages 7 and 15 years regardless of baseline refractive error.
Characteristics and determinants of high-risk unscheduled return visits to the emergency department
Authors: Hiti Eveline A , Tamim Hani , Makki Maha , Geha Mirabelle , Kaddoura Rima , Obermeyer Ziad
Published: December 2019

Background

High-risk unscheduled return visits (HRURVs), defined as return visits within 72 hours that require admission or die in the emergency department (ED) on representation, are a key quality metric in the ED. The objective of this study was to determine the incidence and describe the characteristics and predictors of HRURVs to the ED.

Methods

Case–control study, conducted between 1 November 2014 and 31 October 2015. Cases included all HRURVs over the age of 18 that presented to the ED. Controls were selected from patients who were discharged from the ED during the study period and did not return in the next 72 hours. Controls were matched to cases based on gender, age (±5 years) and date of presentation.

Results

Out of 38 886 ED visits during the study period, 271 are HRURVs, giving an incidence of HRURV of 0.70% (95% CI 0.62% to 0.78%). Our final analysis includes 270 HRURV cases and 270 controls, with an in-ED mortality rate of 0.7%, intensive care unit admission of 11.1% and need for surgical intervention of 22.2%. After adjusting for other factors, HRURV cases are more likely to be discharged with a diagnosis related to digestive system or infectious disease (OR 1.64, 95% CI 1.02 to 2.65 and OR 2.81, 95% CI 1.05 to 7.51, respectively). Furthermore, presentation to the ED during off-hours is a significant predictor of HRURV (OR 1.64, 95% CI 1.11 to 2.43) as is the presence of a handover during the patient visit (OR 1.68, 95% CI 1.02 to 2.75).

Conclusion

HRURV is an important key quality outcome metric that reflects a subgroup of ED patients with specific characteristics and predictors. Efforts to reduce this HRURV rate should focus on interventions targeting patients discharged with digestive system, kidney and urinary tract and infectious diseases diagnosis as well as exploring the role of handover tools in reducing HRURVs.
How to ensure you find the right practice as a newly qualified vet
Authors: Edgley Laura , East Simon
Published: December 2019

Entering the profession as a newly qualified vet can be daunting. While we, as new graduates, are eager to begin our careers in practice, there are many things which we must consider first. This article discusses the factors that influence our decision making when choosing a place of employment and the importance of finding the right place to build confidence and grow during the early stages of our careers.
Dealing with immune‐mediated haematological diseases in dogs and cats 1. Haemolytic anaemia
Authors: Whitley Nat
Published: December 2019

Background: Immune‐mediated haemolytic anaemia (IMHA) is one of the more frequently encountered immune‐mediated diseases and one of the more common causes of severe anaemia in dogs and cats. Autoimmunity typically occurs due to a combination of genetic risk factors and environmental influences. Several dog breeds are predisposed, notably American and English cocker spaniels, springer spaniels, Old English sheepdogs, poodles, Irish setters and dachshunds. Prevalence within a breed may vary with geography and breed line.

Aim of the article: This is the first article in a two‐part series on immune‐mediated haematological diseases in dogs and cats, and focuses on the diagnosis and management of IMHA. The second article, which will be published in the January/February 2020 issue of In Practice, will discuss immune‐mediated thrombocytopenia (IMT) and Evans syndrome (combined IMHA and IMT).
Liquid biopsy for minimally invasive heart transplant monitoring: a pilot study
Authors: Bieńkowski Michał , Pęksa Rafał , Popęda Marta , Kołaczkowska Magdalena , Frankiewicz Anna , Żaczek Anna J , Gruchała Marcin , Biernat Wojciech , Siondalski Piotr
Published: December 2019

Background

Heart transplantation allows for a long-term management of patients with end-stage heart failure. After the surgery, organ rejection is monitored with endomyocardial biopsy, which is an invasive, but not always informative procedure. Therefore, there is a pressing need for a new, safe, yet reliable, diagnostic method. Here, we present a pilot study confronting liquid biopsy based on donor-specific cell-free DNA with the protocol endomyocardial biopsy.

Methods

The study was performed on 21 blood samples matched with endomyocardial biopsy (graded according to acute cellular rejection scale) from nine patients after heart transplantation. Genotyping was performed on genomic DNA from donors and recipients for 10 single-nucleotide polymorphisms (SNPs). Cell-free DNA isolated from plasma was analysed with digital droplet PCR to detect donor-specific alleles.

Results

From 21 analysed endomyocardial biopsies, 4 were graded as 0R and 17 as 1R. Liquid biopsy was successfully performed in each sample for all informative SNPs (median of 3 per patient). We observed a high homogeneity of the results between SNPs in each sample (interclass correlation coefficient of >0.9).

Conclusions

There is a undeniable need for an alternative, non-invasive diagnostic procedure of early transplant rejection and investigation of donor-derived cell-free DNA seems to be the promising choice. The very high sensitivity is particularly enticing to consider liquid biopsy as a potential screening tool. Its minimal invasiveness may allow for more frequent examination and, thus, tighter monitoring. The reliable assessment of its clinical utility requires an adequately powered and properly designed multicentre study.
Digital pathology for intraoperative frozen section diagnosis of thoracic specimens: an evaluation of a system using remote sampling and whole slide imaging diagnosis
Authors: Griffin Jon , Kitsanta Panagiota , Perunovic Branko , Suvarna S Kim , Bury Jonathan
Published: December 2019

Background

Digital pathology is now used for primary diagnostic work as well as teaching, research and consultation. In our multisite institution service reorganisation led to histopathology being located in a separate hospital from some surgical specialities. We implemented remotely supervised specimen sampling and frozen section diagnosis using digital pathology. In this study we assessed the concordance of glass and digital slide diagnosis using this system.

Methods

We reviewed cases from the first 2 years of digital frozen section reporting at our institution. Cases with potential digital to glass slide discordance were reviewed by three experienced thoracic histopathologists. The reasons for discordance were determined and common themes identified. We also reviewed critical incidents relating to digital pathology during the study period.

Results

The study population comprised 211 cases. Frozen section to final diagnosis concordance between digital and glass slide diagnosis was found in 196 (92.6%) cases. The 15 potentially discordant cases were reviewed. Intraobserver concordance between glass and digital slide review ranged from 9/15 to 12/15 cases across the three pathologists. Glass slide review diagnosis showed better concordance with ground truth in two cases; digital slide review was more accurate in two cases. One relevant critical incident was identified during the study period.

Discussion

This is the largest study to examine digital pathology for thoracic frozen section diagnosis and shows that this is a safe and feasible alternative to glass slide diagnosis. Discordance between digital and glass slide diagnoses were unrelated to the processes of whole slide imaging and digital microscopy.
MiR-3150b inhibits hepatocellular carcinoma cell proliferation, migration and invasion by targeting GOLPH3
Authors: Zhang Yi , Wang Jianjun , Su Hongling
Published: December 2019

Background

In this study, we aimed to explore the potential involvement of miR-3150b in hepatocellular carcinoma (HCC) carcinogenesis.

Methods

The expression of miR-3150b and Golgi phosphoprotein 3 (GOLPH3) was determined in HCC cell lines. Cell proliferation, migration and invasion were estimated by Cell Counting Kit-8, wound healing and Transwell assays. The association between miR-3150b and GOLPH3 was verified by luciferase assay.

Results

MiR-3150b was downregulated, while GOLPH3 was remarkably upregulated in HCC cells. Furthermore, miR-3150b inhibited HCC cell proliferation, migration and invasion. MiR-3150b directly targeted and negatively regulated GOLPH3.

Conclusion

MiR-3150b suppressed HCC cell proliferation, invasion and migration by targeting GOLPH3.
Association between midlife dementia risk factors and longitudinal brain atrophy: the PREVENT-Dementia study
Authors: O'Brien John T , Firbank Michael J , Ritchie Karen , Wells Katie , Williams Guy B , Ritchie Craig W , Su Li
Published: December 2019

Background

Increased rates of brain atrophy on serial MRI are frequently used as a surrogate marker of disease progression in Alzheimer’s disease and other dementias. However, the extent to which they are associated with future risk of dementia in asymptomatic subjects is not clear. In this study, we investigated the relationship between the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) risk score and longitudinal atrophy in middle-aged subjects.

Materials and methods

A sample of 167 subjects (aged 40–59 at baseline) from the PREVENT-Dementia programme underwent MRI scans on two separate occasions (mean interval 735 days; SD 44 days). We measured longitudinal rates of brain atrophy using the FSL Siena toolbox.

Results

Annual percentage rates of brain volume and ventricular volume change were greater in those with a high (>6) vs low CAIDE score—absolute brain volume percentage loss 0.17% (CI 0.07 to 0.27) and absolute ventricular enlargement 1.78% (CI 1.14 to 2.92) higher in the at risk group. Atrophy rates did not differ between subjects with and without a parental history of dementia, but were significantly correlated with age. Using linear regression, with covariates of age, sex and education, CAIDE score >6 was the only significant predictor of whole brain atrophy rates (p=0.025) while age (p=0.009), sex (p=0.002) and CAIDE>6 (p=0.017) all predicted ventricular expansion rate.

Conclusion

Our results show that progressive brain atrophy is associated with increased risk of future dementia in asymptomatic middle-aged subjects, two decades before dementia onset.
Protecting health privacy even when privacy is lost
Authors: Kasperbauer T J
Published: December 2019

The standard approach to protecting privacy in healthcare aims to control access to personal information. We cannot regain control of information after it has been shared, so we must restrict access from the start. This ‘control’ conception of privacy conflicts with data-intensive initiatives like precision medicine and learning health systems, as they require patients to give up significant control of their information. Without adequate alternatives to the control-based approach, such data-intensive programmes appear to require a loss of privacy. This paper argues that the control view of privacy is shortsighted and overlooks important ways to protect health information even when widely shared. To prepare for a world where we no longer control our data, we must pursue three alternative strategies: obfuscate health data, penalise the misuse of health data and improve transparency around who shares our data and for what purposes. Prioritising these strategies is necessary when health data are widely shared both within and outside of the health system.
Relationship between diastolic blood pressure and the first ischaemic stroke in elderly patients with hypertension
Authors: Chen Chao-Lei , Huang Jia-Yi , Liu Lin , Yu Yu-Ling , Shen Geng , Lo Kenneth , Huang Yu-Qing , Tang Song-tao , Feng Ying Qing
Published: December 2019

Background

It is uncertain how diastolic blood pressure (DBP) may associate with ischaemic stroke in elder patients with hypertension. We aimed to explore this relationship in a Chinese community.

Methods

A total of 3315 participants aged ≥60 years with essential hypertension were enrolled between January 2010 and December 2011, and being followed up until 31 December 2016. DBP levels were categorised into five groups (<60, 60–70, 70–80, 80–90 and ≥90 mm Hg), using 70–80 mm Hg as referent. We performed Cox regression analysis and subgroup analyses to evaluate the relationship between DBP and the incidence of ischaemic stroke.

Results

Among the 3315 participants, 44.49% were men and they were 71.4 years old on average. During a median follow-up period of 5.5 years, there were 206 onset cases of ischaemic stroke. The HRs for the first ischaemic stroke in the fully adjusted model were 1.32 (95% CI 0.73 to 2.40) for DBP <70 mm Hg, 1.50 (95% CI 1.13 to 2.73) for DBP between 80 and 89.9 mm Hg and 2.31 (95% CI 1.14 to 4.68) for DBP ≥90 mm Hg compared with DBP between 70 and 79.9 mm Hg (p=0.020 for trend). Subgroup and interaction analysis showed no significant findings.

Conclusions

DBP had a non-linear association with the risk of ischaemic stroke among Chinese elderly patients with hypertension. DBP between 70 and 80 mm Hg may be an appropriate indicator for a lower stroke risk.
Role of routine use of ultrasonographic guidance for performing lumbar punctures
Authors: Halkur Shankar Sujay , Biswas Sagnik , Kumar Arvind , Gupta Akshita , Goel Aastha , Khan Maroof Ahmad , Singh Rajesh Kumar , Ranjan Piyush , Soneja Manish , Wig Naveet
Published: December 2019

Purpose of study

Ultrasound (US) for lumbar puncture has seen the most success in obese patients and in patients with difficult to palpate landmarks. We aimed to elucidate the advantage of the use of routine US for performing lumbar punctures over the traditional landmark method.

Study design

This was a prospective study with consecutive sampling with a sample size of convenience. Three residents were chosen to perform the lumbar punctures after a training session. Patients were assigned to either the US group or the landmark group. The outcomes studied were number of attempts at needle insertion, patient and physician anxiety, pain experienced, time to procedure, number of traumatic attempts and the difficulties faced during the procedure.

Results

A total of 77 patients were included in this study, of which 36 patients (46.8%) underwent landmark-based lumbar puncture and 41 (53.2%) underwent US-guided lumbar puncture. There was no statistically significant difference between the two groups among the following characteristics: number of attempts to a successful procedure, number of traumatic punctures, procedure time, preprocedure anxiety of the participants and physicians and pain score rating of the procedure.

Conclusion

There was no significant difference between the landmark method and US-guided method for performing lumbar puncture in the number of successful attempts, number of traumatic punctures, procedure time and pain during the procedure. Further studies are required to elucidate the advantage of the use of ultrasonography in subsets of the population such as the low body mass index population.
‘Cattle infectivity is driving the bTB epidemic’
Authors: McGill Iain , Jones Mark
Published: December 2019

Iain McGill and Mark Jones argue that recent data released by the APHA show that it is the prevalence or ‘infectivity’ of cattle that is sustaining bTB infection and driving transmission of Mycobacterium bovis to new herds.