bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration Characteristics of Island-Bridge Structure on Porous PDMS Substrates for Stretchable Electronics
Authors: Song Xin , Bian Zuguang , Zhou Xiaoliang , Huang Zhuye
Published: September 2021

Stretchable electronics employing island-bridge structure design can achieve controllable and reversible stretchability. The use of a porous substrate, which provides excellent breathability for wearable devices bonded to skin, not only satisfies this static superiority but also has a profound impact on the dynamic performance of the stretchable electronics. In this paper, the vibration characteristics of the island-bridge structure based on porous polydimethylsiloxane (p-PDMS) substrates are studied by utilizing an analytical model, which takes account of geometric nonlinearity due to mid-plane stretching, buckling configuration, elastic boundary conditions considering the p-PDMS substrates and the mass of the island. In numerical examples, the accuracy of the analytical model is first verified by finite element analysis (FEA). After that, we investigate the effects of some primary factors, i.e., the prestrain of the substrate, spring stiffnesses at the ends of the interconnect, porosity and thickness of the substrate, and the mass of the island, on the natural frequencies and vibration mode shapes of the island-bridge structure. Results show that the vibration characteristics of the island-bridge structure can be tuned conveniently by adjusting the porosity of the substrate and the mass of the island, which are expected to be helpful to mechanical design and optimization of stretchable electronics in complex noise environments.
Evidence-Theory-Based Reliability Analysis Through Kriging Surrogate Model
Authors: Zhang Dequan , Liang Yunfei , Cao Lixiong , Liu Jie , Han Xu
Published: September 2021

It is generally understood that intractable computational intensity stemming from repeatedly calling performance function when evaluating the contribution of joint focal elements hinders the application of evidence theory in practical engineering. In order to promote the practicability of evidence theory for the reliability evaluation of engineering structures, an efficient reliability analysis method based on the active learning Kriging model is proposed in this study. To start with, a basic variable is selected according to basic probability assignment (BPA) of evidence variables to divide the evidence space into sub-evidence spaces. Intersection points between the performance function and the sub-evidence spaces are then determined by solving the univariate root-finding problem. Sample points are randomly identified to enhance the accuracy of the subsequently established surrogate model. Initial Kriging model with high approximation accuracy is subsequently established through these intersection points and additional sample points generated by Latin hypercube sampling. An active learning function is employed to sequentially refine the Kriging model with minimal sample points. As a result, belief (Bel) measure and plausibility (Pl) measure are derived efficiently via the surrogate model in the evidence-theory-based reliability analysis. The currently proposed analysis method is exemplified with three numerical examples to demonstrate the efficiency and is applied to reliability analysis of positioning accuracy for an industrial robot.
Heat Transfer in a Rotating, Blade-Shaped, Two-Pass Cooling Channel With a Variable Aspect Ratio
Authors: Chen I-Lun , Sahin Izzet , Wright Lesley M. , Han Je-Chin , Krewinkel Robert
Published: September 2021

This study features a rotating, blade-shaped, two-pass cooling channel with a variable aspect ratio (AR). Internal cooling passages of modern gas turbine blades closely follow the shape and contour of the airfoils. Therefore, the cross section and the orientation with respect to rotation varies for each cooling channel. The effect of passage orientation on the heat transfer and pressure loss is investigated by comparing to a planar channel design with a similar geometry. Following the blade cross section, the first pass of the serpentine channel is angled at 50 deg from the direction of rotation while the second pass has an orientation angle of 105 deg. The coolant flows radially outward in the first passage with an AR = 4:1. After a 180-deg tip turn, the coolant travels radially inward into the second passage with AR = 2:1. The copper plate method is applied to obtain the regionally averaged heat transfer coefficients on all the interior walls of the cooling channel. In addition to the smooth surface case, 45 deg angled ribs with a profiled cross section are also placed on the leading and trailing surfaces in both the passages. The ribs are placed such that P/e = 10 and e/H = 0.16. The Reynolds number varies from 10,000 to 45,000 in the first passage and 16,000 to 73,000 in the second passage. The rotational speed ranges from 0 to 400 rpm, which corresponds to maximum rotation numbers of 0.38 and 0.15 in the first and second passes, respectively. The blade-shaped feature affects the heat transfer and pressure loss in the cooling channels. In the second passage, the heat transfer on the outer wall and trailing surface is higher than the inner wall and leading surface due to flow impingement and the swirling motion induced by the blade-shaped tip turn. The rotational effect on the heat transfer and pressure loss is lower in the blade-shaped design than the planar design due to the feature of angled rotation. The tip wall heat transfer is significantly enhanced by rotation in this study. The overall heat transfer and pressure loss in this study is higher than the planar geometry due to the blade-shaped feature. The heat transfer and pressure loss characteristics from this study provide important information for the gas turbine blade internal cooling designs.
Design of Torque-Compensated Mechanical Systems With Two Connected Identical Slider-Crank Mechanisms
Authors: Arakelian Vigen
Published: September 2021

Balancing the torque of mechanisms designed to minimize the fluctuation of input shaft torque is an effective means of improving their dynamic performance. There are several ways of solving the problem: optimizing the distribution of the moving mass of the original mechanism; cam sub-systems that displace the balancing mass; cam-spring mechanisms; flywheels driven by noncircular gears; adding articulated dyads, linkages or redundant drivers. This paper addresses the problem of input torque compensation with the optimal connection of two identical slider-crank mechanisms. The acceleration and deceleration phases of the links of the slide-crank mechanism obviously change periodically, causing torque to fluctuate at the input shaft. The problem is how to connect two mechanisms in order to reduce the input torque. This is done by minimizing the root-mean-square value of the input torque of the combined linkages. Two schemes are considered: slider-crank mechanisms with sliders moving on the same side, and on opposite sides. The prime value of this study is that it proposes an analytically tractable solution for identifying the general dynamic properties of mechanisms. Based on the ratio of link lengths, the precise relations for optimal connection of identical slider-crank mechanisms, i.e., a connection that produces the minimum root-mean-square values of the input torque, are developed. The numerical simulations illustrate the efficiency of the suggested approach. Observations show that the best solutions from the point of view of input torque minimization are obtained for the value of the coupling angle of two mechanisms around 90 deg.
Exact Path Synthesis of RCCC Linkages for a Maximum of Nine Prescribed Positions
Authors: Bai Shaoping , Li Zhongyi , Angeles Jorge
Published: September 2021

This article addresses the path synthesis of RCCC (revolute-cylindrical-cylindrical-cylindrical) linkages, a problem that has not received due attention in the literature. Compared with planar and spherical four-bar linkages, a RCCC linkage has many more design parameters, which lead to a complex formulation of the path synthesis problem and, consequently, to a quite challenging system of algebraic equations. In this article, the problem is solved with a novel formulation of path synthesis for visiting a number of prescribed positions. This is achieved by means of an alternative coordinate system, which allows point coordinates to be expressed with the aid of two vectors fixed to the same body. By this means, the rotation matrix used to represent the coupler link attitude is obviated. The synthesis equations are then formulated in a simple form. Our formulation confirms that path synthesis admits exact solutions for up to nine prescribed positions, which proves a landmark claim submitted by Burmester. Examples are included to demonstrate the path synthesis procedure with the method thus developed.
Impact of Ceramic Matrix Composite Topology on Friction Factor and Heat Transfer
Authors: Cory Trevor M. , Edelson Ryan D. , Thole Karen A. , Vincent Tyler , Quach San , Mongillo Dominic
Published: September 2021

Ceramic matrix composites (CMCs) are of interest for hot section components of gas turbine engines due to their low weight and favorable thermal properties. To implement this advanced composite in a gas turbine engine, characterizing the influence of CMC’s surface topology on heat transfer and cooling performance is critical. However, very few published studies have reported the flow and heat transfer effects caused by this unique surface topology. This study is an experimental and computational investigation to evaluate the effect of weave orientations, relevant to CMC surfaces, on the resulting pressure loss and convective heat transfer within an internal channel. The weave pattern was additively manufactured as the walls of a scaled-up coupon containing a single channel. For each of the three weave orientations, bulk pressure losses and convective heat transfer coefficients were measured over a range of Reynolds numbers. Scaling the pressure losses in terms of a friction factor and convective heat transfer coefficients in terms of a Nusselt number showed the importance of choosing the appropriate definition of the hydraulic diameter, which was particularly important for the friction factor. A coupon having one wall with the weave surface increased pressure loss and heat transfer compared to a smooth wall with the largest increases occurring when the CMC weave strands were perpendicular to the flow. Friction factor augmentations were much higher than heat transfer augmentations. When adding the weave to a second channel wall, pressure loss and heat transfer were further increased. Orienting the CMC strands perpendicular to the flow consistently showed the largest augmentations in heat transfer over a smooth channel, but at a much higher pressure loss penalty than that seen with the CMC strands parallel to the flow.
Mitigating barriers to addiction recovery in Aotearoa New Zealand: A lived experience perspective
Authors: Jowett Rachel Victoria , Dale Michael , Cooper Lareen
Published: September 2021

INTRODUCTION: The New Zealand government’s health surveys consistently identify that alcohol and other drug (AOD) addiction is an issue for New Zealanders. However, there is a lack of qualitative research on the lived experiences of health and social service professionals who have previous or current experience of AOD addiction in Aotearoa New Zealand.METHODS: A constructivist approach was utilised, semi-structured interviews were conducted, and subsequent thematic analysis identified themes highlighting what contributed, and created barriers to, participants’ successful AOD addiction recovery.FINDINGS: Identification of nine themes illustrated that the barriers to AOD addiction recovery in Aotearoa New Zealand experienced by the research participants were systemic and preventable.CONCLUSIONS: The recommendation of this research is that the lived experience of people who have experienced AOD addiction in Aotearoa New Zealand is better utilised in order to mitigate, and enhance, identified barriers, and contributors to, successful AOD addiction recovery.
Eye Accommodation, Near Vision, and Far Vision from a Geometrical Optics Point of View
Authors: Asadollahi Zahra , Andrianarijaona Vola M.
Published: September 2021

The eye should have a particular focal length in order to see an object. As there are many things to see, the focal length of the eye must vary because these things are not all at the same distance from the eye. We explore the eye accommodation from a geometrical optics point of view and present our results in this paper; the study includes a description of the accommodation mechanism and a scientific definition of near vision and far vision.
Reflections on a Competency-Based Physics Course
Authors: Binder P.-M. , Blue Hannah L.
Published: September 2021

Physics courses that focus on developing and assessing student competency through the use of standards have successfully been implemented in the past. It appears to be the case that not enough practical information is available to instructors planning to engage on this modality.
The Ball Bearing High Voltage Generator – A Demonstration Apparatus Illustrating Electrostatic Concepts at Multiple Levels
Authors: Pfister Hans
Published: September 2021

The Ball Bearing High Voltage generator is a fairly simple and transparent apparatus that can serve as a tool to motivate conceptual descriptions and calculations in electrostatics that are normally presented to our students in a rather dry and matter-of-fact fashion.
Using the Thomson Jumping Ring to Study the Effect of Eddy Currents and Skin Depth on Ring Jump Height
Authors: McCaughin Patrick , Ford Lyle
Published: September 2021

Since its debut in Elihu Thomson’s 1886 article “Novel Phenomena of Alternating Currents,” the Thomson jumping ring apparatus has been a popular and captivating demonstration of magnetic induction. The components are quite simple. There is a solenoid, an iron core, and a ring. The demonstration usually begins with the professor saying something along the lines of, “An alternating current introduced to the solenoid will create a changing magnetic field, which induces a current in the ring in such a way to oppose the changing flux of the magnetic field responsible for the creation of the ring current. This will make the ring jump!” The professor then turns a switch, the ring is instantaneously launched into the air, and a classroom of students is amazed. The behavior of the demonstration is then attributed Lenz’s law and the lecture moves on.
Graphic Relation Between Amplitude and Sound Intensity Level
Authors: Pinochet Jorge , Cortada Walter Bussenius , Peña Mauricio Sánchez
Published: September 2021

We present a simple experiment that allows us to demonstrate graphically that the intensity of sound waves is proportional to the square of their amplitude, a result that is theoretically analyzed in any introductory wave course but rarely demonstrated empirically. To achieve our goal, we use an audio signal generator that, when connected to a loudspeaker, produces sine waves that can easily be observed and measured using an oscilloscope. The measurements made with these instruments allow us to create a plot of amplitude vs. sound intensity level, which verifies the mathematical relationship between amplitude and intensity mentioned above. Among the experimental errors, the plot obtained is in excellent agreement with what is theoretically expected.
Demonstrating Conical Pendulum Stable and Unstable States
Authors: Minkin Leonid , Sikes Daniel
Published: September 2021

This article analyzes and experimentally verifies the stability behavior of the equilibrium states of a conical pendulum. An analysis of the motion presents that the equilibrium states of the pendulum are determined by the pendulum angular speed. For a given pendulum length there exists a critical angular speed that determines stability conditions. Experimental results obtained using a variable speed rotator confirm the relationship between angular speed and equilibrium state conditions. An initially at rest pendulum has a stable equilibrium position that is vertically hanging straight down; however, it is shown that when gradually increasing the speed of a mechanical rotator to approach and surpass the pendulum critical speed, the initial stable equilibrium state becomes unstable. Furthermore, the pendulum, now in an unstable equilibrium, moves to a new stable equilibrium position that did not exist at speeds below the critical speed.
Use of a Simple Homemade Apparatus to Teach Basic Thermal Concepts – Six Qualitative Demonstrations/Experiments
Authors: Stylos Georgios , Kotsis Konstantinos T.
Published: September 2021

Understanding thermal concepts constitutes one of the most important challenges in teaching science as these concepts are central to the principals of science and allow students to build connections among scientific disciplines. From an early age, students’ interaction with daily phenomena and real situations comes to shape their conceptions of thermal concepts, which continues to guide them throughout their education. Conceptions that are sometimes different from the scientific norm. This article presents six qualitative experiments/demonstrations using a low-cost, easy to make apparatus that introduces students to thermal concepts such as heat conduction in solid bodies and thermal expansion. These are appropriate for high school or college students enrolled in non-major science courses (e.g., departments of primary education) and can easily be performed by elementary or middle school students, but care must be taken when dealing with tealight candle flames.
Studying the Rate of Evaporation Using Pocket and Computer-Supported Weighing Scales
Authors: Kácovský Petr
Published: September 2021

Already when they enter primary school, children have rich everyday experience with factors influencing the rate of liquids’ evaporation. Tea spilled into a large puddle on the table evaporates more rapidly than the same amount remaining in the cup, laundry hanging on a clothesline dries faster on a hot and windy day in comparison with a cold and windless one. We use examples such as these when we tell students that the rate of evaporation is affected by the temperature of a liquid, its surface area, and the airflow above the surface that accelerates the removal of vapors; the type of liquid is also essential. This paper describes a simple way of approximate quantification of these effects in a few hands-on experiments using weighing scales.
Determining the coefficient of kinetic friction using smartphone sensors
Authors: Puttharugsa Chokchai , Wicharn Surawut , Plaipichit Suwan , Khemmani Supitch
Published: September 2021

Nowadays, smartphones play an important role in the physics laboratory as well as in Arduino-based sensors. Some recent examples include the analysis of acoustic experiments with mobile devices, mechanics experiments such as those on linear and circular motion as well as simple/damped harmonic motion. Smart phones can accurately record experimental data using internal sensors (e.g., accelerometer, gyroscope, magnetometer) via appropriate applications (apps), such as phyphox, SensorLog, and SensorKineticsPro. Moreover, students are familiar with using smartphones and these apps, making these experiments interesting and easy for them to perform. The coefficient of static/kinetic friction can be measured using smartphone sensors, as seen in previous reports. Typically, the coefficient of kinetic friction can be determined by measuring the acceleration of a sliding object (smartphone) on an inclined or horizontal plane. In this paper, we propose alternative methods to measure the coefficient of kinetic friction between a smartphone and paper in linear and circular motions using the smartphone’s sensors. In the experiment, the acceleration of the sliding object (smartphone) is measured using the linear motion method, while its angular speed is measured using the circular motion method. The experimental data are then sent to the user for analysis to determine the coefficient of kinetic friction. The results obtained from the linear motion method are in good agreement with those obtained from the circular motion method.
I’m still standing
Authors: Lazarova Mariana
Published: September 2021

The ’80s are back. And not only because Elton John’s upbeat 1983 single “I’m Still Standing” has been a frequent background to my train of thoughts lately: “I’m still standing better than I ever didLooking like a true survivor, feeling like a little kid,”
Inexpensive Physical Pendulum with Arduino
Authors: Lukovic Milentije , Lukovic Vanja , Bozic Milos , Vujicic Vojislav
Published: September 2021

One of the contemporary trends in the development of physics teaching is its integration with computers. Introducing computers and microcontrollers into the teaching of physics opens up completely new possibilities for explaining different physical phenomena. Microcontrollers allow the experiment to be brought back to the focus of physics teaching in a new and different way that is far more contemporary and more receptive to new generations of students.
Fostering Students’ Values Through Role Play about Socioscientific Issues
Authors: Namdar Bahadir , Namdar Aysegul Oguz
Published: September 2021

During the course of international curriculum reform, decision making about socioscientific issues (SSI)—open-ended controversial issues with connections to science, technology, and society—has been labeled a critical tool for achieving scientific literacy. Therefore, enhancing students’ socioscientific decision making as part of science education has become a pressing issue; global SSI affect people every day. This leads people worldwide to collaboratively involve in decision-making processes to solve these ill-structured problems for the sake and safety of humanity. Values are core principles and guidelines that support socioscientific decision making. Therefore, recent conceptualizations of scientific literacy also consider values a core component of this vision of science education. However, few instructional strategies have been provided to support students’ enactment of character and values. Role play has proven to be an effective way of socioscientific decision making because it can empower students’ emotive, intuitive, and ethical reasoning, through which students can enact and develop values regarding SSI. In this paper, we provide an example lesson plan for fostering high school students’ values and decision making about the issue of nuclear energy through role play.
Teaching University Physics Courses During the Coronavirus Pandemic (COVID-19)
Authors: Mali Petar
Published: September 2021

The pandemic caused by COVID-19 has induced health emergencies followed by changes in social life and education. The transition to online teaching might be harder or easier depending on the situation in a particular country, as well as on the curriculum of teaching subjects and teaching methods that are used. In this paper the methods used in summer semester of 2020 at the University of Novi Sad are presented. For teaching different theoretical physics courses, the Discord platform and graphics tablet have been used. This analysis shows that although online teaching in this form may not be a suitable replacement, it has certain advantages compared to standard classroom teaching.
Maintaining Essential Course Features When Moving Introductory Physics Labs Online
Authors: Koenig Kathleen , Bake Sarah
Published: September 2021

The sudden transition to online teaching due to the pandemic in spring 2020 provided us the opportunity to experience firsthand the challenges involved in delivering labs online. After learning that our introductory lab courses would be taught online fall 2020 and spring 2021, which involve over 2200 students, the decision was made to invest significant effort into redesigning the labs for online delivery, and this effort became part of the teaching load for the first author. This paper discusses the decisions made, innovations implemented to maintain essential features of our in-person labs, and lessons learned.
tRNA overexpression rescues peripheral neuropathy caused by mutations in tRNA synthetase
Authors: Zuko Amila , Mallik Moushami , Thompson Robin , Spaulding Emily L. , Wienand Anne R. , Been Marije , Tadenev Abigail L. D. , van Bakel Nick , Sijlmans Céline , Santos Leonardo A. , Bussmann Julia , Catinozzi Marica , Das Sarada , Kulshrestha Divita , Burgess Robert W. , Ignatova Zoya , Storkebaum Erik
Published: September 2021

Defeating peripheral neuropathy

The mechanisms underlying peripheral neuropathies are not well understood. Spaulding
et al
. studied mouse models of the inherited Charcot-Marie-Tooth (CMT) disease, which is caused by mutations in transfer RNA (tRNA) synthetases. Changes in gene expression and the rate of protein synthesis in neurons in the spinal cord triggered the cell stress response activated by the protein sensor GCN2. When GCN2 was genetically deleted or inhibited with drugs, the stress response was blocked, and the neuropathy was much milder. Zuko
et al
. found that mutant glycyl-tRNA synthetases bind tRNA
Gly
but fail to release it, thus depleting the cellular tRNA
Gly
pool. This process caused stalling of translating ribosomes on glycine codons and activated the integrated stress response. Transgenic tRNA
Gly
overexpression prevented peripheral neuropathy and protein synthesis defects in mouse and fruit fly models. Thus, elevating tRNA
Gly
levels or targeting GCN2 may have therapeutic potential for this currently untreatable disease (see the Perspective by Mellado and Willis). —SMH
A transient radio source consistent with a merger-triggered core collapse supernova
Authors: Dong D. Z. , Hallinan G. , Nakar E. , Ho A. Y. Q. , Hughes A. K. , Hotokezaka K. , Myers S. T. , De K. , Mooley K. P. , Ravi V. , Horesh A. , Kasliwal M. M. , Kulkarni S. R.
Published: September 2021

Radio evidence of a stellar merger

Core collapse supernovae occur when a massive star exhausts its fuel and explodes. Theorists have predicted that a similar explosion could occur if an evolved massive star merges with a compact companion, such as a neutron star. Dong
et al
. have identified a radio source that was not present in earlier radio surveys. Follow-up radio and optical spectroscopy show that it is an expanding supernova remnant slamming into surrounding material, probably ejected from the star centuries before it exploded. An unidentified x-ray transient occurred at a consistent location in 2014, suggesting an explosion at that time that produced a jet. The authors suggest that the most likely explanation is a merger-triggered supernova. —KTS
A quantum vortex made of atoms
Authors: Kornilov Oleg
Published: September 2021

Vortex states seen for photons and electrons have been created in rare gas atoms and dimers
A reservoir of stem-like CD8
+
T cells in the tumor-draining lymph node preserves the ongoing antitumor immune response
Authors: Connolly Kelli A. , Kuchroo Manik , Venkat Aarthi , Khatun Achia , Wang Jiawei , William Ivana , Hornick Noah I. , Fitzgerald Brittany L. , Damo Martina , Kasmani Moujtaba Y. , Cui Can , Fagerberg Eric , Monroy Isabel , Hutchins Amanda , Cheung Julie F. , Foster Gena G. , Mariuzza Dylan L. , Nader Mursal , Zhao Hongyu , Cui Weiguo , Krishnaswamy Smita , Joshi Nikhil S.
Published: September 2021

Tumor-specific CD8
+
T cells in stable tumor-draining lymph node reservoir are clonally and developmentally related to those in tumors.
Use of artificial intelligence for image analysis in breast cancer screening programmes: systematic review of test accuracy
Authors: Freeman Karoline , Geppert Julia , Stinton Chris , Todkill Daniel , Johnson Samantha , Clarke Aileen , Taylor-Phillips Sian
Published: September 2021

Objective

To examine the accuracy of artificial intelligence (AI) for the detection of breast cancer in mammography screening practice.

Design

Systematic review of test accuracy studies.

Data sources

Medline, Embase, Web of Science, and Cochrane Database of Systematic Reviews from 1 January 2010 to 17 May 2021.

Eligibility criteria

Studies reporting test accuracy of AI algorithms, alone or in combination with radiologists, to detect cancer in women’s digital mammograms in screening practice, or in test sets. Reference standard was biopsy with histology or follow-up (for screen negative women). Outcomes included test accuracy and cancer type detected.

Study selection and synthesis

Two reviewers independently assessed articles for inclusion and assessed the methodological quality of included studies using the QUality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A single reviewer extracted data, which were checked by a second reviewer. Narrative data synthesis was performed.

Results

Twelve studies totalling 131 822 screened women were included. No prospective studies measuring test accuracy of AI in screening practice were found. Studies were of poor methodological quality. Three retrospective studies compared AI systems with the clinical decisions of the original radiologist, including 79 910 women, of whom 1878 had screen detected cancer or interval cancer within 12 months of screening. Thirty four (94%) of 36 AI systems evaluated in these studies were less accurate than a single radiologist, and all were less accurate than consensus of two or more radiologists. Five smaller studies (1086 women, 520 cancers) at high risk of bias and low generalisability to the clinical context reported that all five evaluated AI systems (as standalone to replace radiologist or as a reader aid) were more accurate than a single radiologist reading a test set in the laboratory. In three studies, AI used for triage screened out 53%, 45%, and 50% of women at low risk but also 10%, 4%, and 0% of cancers detected by radiologists.

Conclusions

Current evidence for AI does not yet allow judgement of its accuracy in breast cancer screening programmes, and it is unclear where on the clinical pathway AI might be of most benefit. AI systems are not sufficiently specific to replace radiologist double reading in screening programmes. Promising results in smaller studies are not replicated in larger studies. Prospective studies are required to measure the effect of AI in clinical practice. Such studies will require clear stopping rules to ensure that AI does not reduce programme specificity.

Study registration

Protocol registered as PROSPERO CRD42020213590.
Paediatric surgical outcomes in sub-Saharan Africa: a multicentre, international, prospective cohort study
Authors:   PaedSurg Africa Research Collaboration
Published: September 2021

Introduction

As childhood mortality from infectious diseases falls across sub-Saharan Africa (SSA), the burden of disease attributed to surgical conditions is increasing. However, limited data exist on paediatric surgical outcomes in SSA. We compared the outcomes of five common paediatric surgical conditions in SSA with published benchmark data from high-income countries (HICs).

Methods

A multicentre, international, prospective cohort study was undertaken in hospitals providing paediatric surgical care across SSA. Data were collected on consecutive children (birth to 16 years), presenting with gastroschisis, anorectal malformation, intussusception, appendicitis or inguinal hernia, over a minimum of 1 month, between October 2016 and April 2017. Participating hospitals completed a survey on their resources available for paediatric surgery.

The primary outcome was all-cause in-hospital mortality. Mortality in SSA was compared with published benchmark mortality in HICs using χ2analysis. Generalised linear mixed models were used to identify patient-level and hospital-level factors affecting mortality. A p<0.05 was deemed significant.

Results

1407 children from 51 hospitals in 19 countries across SSA were studied: 111 with gastroschisis, 188 anorectal malformation, 225 intussusception, 250 appendicitis and 633 inguinal hernia. Mortality was significantly higher in SSA compared with HICs for all conditions: gastroschisis (75.5% vs 2.0%), anorectal malformation (11.2% vs 2.9%), intussusception (9.4% vs 0.2%), appendicitis (0.4% vs 0.0%) and inguinal hernia (0.2% vs 0.0%), respectively. Mortality was 41.9% (112/267) among neonates, 5.0% (20/403) in infants and 1.0% (7/720) in children. Paediatric surgical condition, higher American Society of Anesthesiologists score at primary intervention, and needing/receiving a blood transfusion were significantly associated with mortality on multivariable analysis.

Conclusion

Mortality from common paediatric surgical conditions is unacceptably high in SSA compared with HICs, particularly for neonates. Interventions to reduce mortality should focus on improving resuscitation and timely transfer at the district level, and preoperative resuscitation and perioperative care at paediatric surgical centres.
Scared, powerless, insulted and embarrassed: hesitancy towards vaccines among caregivers in Cavite Province, the Philippines
Authors: Landicho-Guevarra Jhoys , Reñosa Mark Donald C , Wachinger Jonas , Endoma Vivienne , Aligato Mila F , Bravo Thea Andrea , Landicho Jeniffer , Bärnighausen Kate , McMahon Shannon A
Published: September 2021

Background

Several studies have highlighted that vaccine hesitancy (VH) is among the most important threats to global health, especially in low- and middle-income countries, including the Philippines. However, there is a dearth of literature exploring family experiences of—or concerns related to—childhood vaccinations that gives voice to vaccine hesitant caregivers (VHCs) of small children. Here, we present insights from VHCs from the Philippines.

Methods

This research draws on in-depth interviews (IDIs) with 44 VHCs who had previously delayed or refused vaccination for their children in rural and urban communities in Cavite Province, the Philippines. Amid the COVID-19 pandemic, we conducted IDIs via an online platform of the respondents’ choosing (ie, Facebook messenger call, Skype and Zoom). All interviews were recorded, transcribed, translated and analysed drawing from the tenets of constructivist grounded theory. We use the social ecological model to structure our results.

Results

Among the reasons for delay or refusal of childhood vaccinations, a fear of side effects emerged as the most salient concern, exacerbated by previous negative experiences (including trauma) from a dengue vaccine controversy in 2017. Respondents cited the dengue vaccine controversy as they expressed reluctance (regarding any new vaccines) and suspicion (towards school-based vaccination, the distribution channel used for the dengue vaccine). Heads of households opposing vaccines, perceptions that vaccines are non-essential and influences from the social and traditional media or neighbours contributed to further refusal and delay. Upon probing, VHCs recounted health system concerns particularly with regards to healthcare workers who are sometimes unable to answer their questions and can be dismissive or disrespectful regarding caregivers’ concerns.

Conclusion

Understanding VH from the lens of VHCs highlights pathways for interventions to regain trust and bolster confidence towards vaccines. Our findings may serve as linchpins in the development of VH interventions aiming at changing behaviour on a population scale.
Rapid assessment of prevalence of blindness and cataract surgery in Kabul province, Afghanistan
Authors: Sapkota Yuddha , Alizoi Najeebullah , Siddiqi Abdul Majeed , Naseem Mohammad , Salaam Ahmad Shah , Rehman Atiq ur , D'Esposito Fabrizio , Das Taraprasad
Published: September 2021

Objective

To estimate prevalence and causes of blindness and vision impairment and assess cataract surgical coverage and quality of cataract surgery in Kabul.

Methods and analysis

A total of 3751 adults aged 50 years and above were recruited from 77 randomly selected clusters. Each participant underwent presenting and pinhole visual acuity assessment and lens examination. Those with pinhole visual acuity <6/12 in either eye had a dilated fundus examination to determine the cause of reduced vision. Those with apparent lens opacity were interviewed on barriers to cataract surgery.

Results

The age-adjusted and sex-adjusted prevalence of blindness was 2.4% (95% CI: 1.8% to 3.0%). Prevalence of severe, moderate and mild vision impairment was 2.2% (95% CI: 1.7% to 2.7%), 6.9% (95% CI: 6.0% to 7.9%) and 8.7% (95% CI: 7.5% to 9.8%), respectively. Cataract was the main cause of blindness (36.8%), severe (54.4%) and moderate (46.1%) vision impairment. Uncorrected refractive error was the leading cause of mild vision impairment (20.3%). Age-related macular degeneration was the second leading cause of blindness (23.0%). In people with a presenting visual acuity of <3/60, cataract surgical coverage was 89.7%, and effective cataract surgical coverage was 67.8%. The major barriers to uptake of the available cataract surgical services were the need for surgery was not felt (23.7%) and cost (22.0%).

Conclusion

Kabul province has a high prevalence of blindness, largely due to cataract and age-related macular generation. The quality of cataract surgery is also lagging in terms of good visual outcomes. This calls for immediate efforts to improving the reach and quality of existing eye services and readiness to respond to the increasing burden of posterior eye disease.
Acute hospital preoperative assessment redesign: streamlining the patient pathway and reducing on-the-day surgery cancellations
Authors: Brazil Debbie , Moss Charlotte , Blinko Karen
Published: September 2021

Introduction

Avoidable surgery cancellations in an acute trust were often attributed to inadequate preoperative assessment. These assessments, undertaken shortly before surgery, were delivered across eight different locations, 60% by a central nursing team and the remainder by other healthcare professionals. There was inconsistency in what and who were assessed, and inadequate time to optimise patients. There was difficulty finding capacity for urgent patient assessment, plus a lack of a pool of ‘ready-assessed’ patients to fill last-minute operating list gaps.

Methods

A diagnostic phase using data analysis, root cause analyses and clinic observations identified multiple systemic issues confirming the need for system change.

Interventions

Other trusts operating different models were visited and their processes were adapted to create a preassessment model relevant to our trust context. Key features included early preassessment, triage and streaming, in-clinic support from a prescribing pharmacist and consultant anaesthetist, a standardised outcome form documenting specific patient requirements needing action when a surgery date was agreed, surgery dating only on confirmation of patient optimisation, an administrative office (hub) with a tracking database to coordinate follow-up tasks and a patient hotline. A key enabler was a single, bespoke location. Where possible, testing took place in advance of the go-live. However, due to the transformational nature of the new model, some changes could only be tested and refined at scale in the new, single location.

Results

Two months post implementation, a preliminary audit was positive, but clinic observations indicated that patient clinic flow was suboptimal. Further structural and process modifications were made. Ten months post implementation, a further root cause audit showed a near-elimination of on-the-day surgery cancellations for patients assessed in the redesigned service.

Conclusion

The bundle of 17 interlinked interventions proved highly effective in delivering sustained improvements, which could be adopted by other trusts.
Therapeutic duplication on the general surgical wards
Authors: Huynh Isabelle , Rajendran Tania
Published: September 2021

Therapeutic duplication is the practice of prescribing multiple medications for the same indication or purpose without a clear distinction of when one agent should be administered over another. This is a problem that occurs frequently, especially on electronic prescribing records (EPR) as the medication chart is not always reviewed before prescribing. The aim of this Quality Improvement Project (QIP) was to reduce therapeutic duplication to 0% through educating the general surgical team. Prescriptions of all general surgical patients in the surgical wards were reviewed daily for a month. EPR was used to check if there were any duplications or identical class of drug prescribed. Patient documentation was thoroughly checked to rule out if the duplication was intentional. Following this, if duplication was still unclear, the relevant teams would be contacted for clarification. Any unintentional error was removed, and data was collected. The QIP results were presented to the local general surgical meeting and our fellow colleagues were educated on the importance of safe prescribing and on how to prevent prescribing errors. The baseline of therapeutic duplications on the general surgical wards was 9% prior to our first cycle. Following the presentation of data and educating the surgical team at the surgical meeting, the number of errors seemingly reduced, however, there was a jump to 22% of therapeutic duplication on a particular Friday which brought the average of therapeutic duplication to 8.77%. The team was reminded again about the importance of correct prescribing and after the second cycle, the number of errors reduced to 5.29%. For the third audit cycle, the team was presented with the reaudited data and following this, the number of errors dropped down to 3.12%. Therapeutic duplication should never occur as this could cause a risk to patient harm. Through educating the surgical team and reminding our team regularly, the average number of errors reduced by more than half of the original number. In our hospital, the main source of safety net is through pharmacists and nurses, however as shown, this is not enough to prevent all therapeutic errors. A more sustainable intervention such as an alert on EPR prior to prescribing may be required to maintain a low therapeutic duplication average and prevent patient harm.
Clinical presentation and serological diagnosis of syphilis reinfection in men living with HIV: a retrospective cohort study
Authors: Mischler-Gornostaeva Ksenia , Glatz Martin , Fehr Jan , Bosshard Philipp Peter
Published: September 2021

Objectives

Studies on the characteristics of syphilis reinfection are scarce despite increasing numbers and proportions of cases. We aimed to gain insights into the clinical and serological presentation of reinfected men living with HIV and to evaluate diagnostic criteria for syphilis reinfection.

Methods

We conducted a retrospective cohort study of 259 HIV-positive men diagnosed with syphilis between January 1999 and September 2015 at the University Hospital Zurich. We compared patients with a single syphilis infection (n=109) to patients with reinfections (n=150).

Results

The two groups matched in age, sexual orientation and numbers of other STIs. Reinfected patients more often presented with latent syphilis than patients with a single syphilis episode (41.9% vs 8.9%; p<0.001). Although generally high venereal diseases research laboratory (VDRL) or rapid plasma reagin (RPR) titres (median 1:32) were seen in reinfected patients, 19.4% had titres ≤1:8. Treponema pallidum passive particle agglutination (TPPA) titres were significantly higher (1:81 840 vs 1:10 240; p<0.001), while IgM values were significantly lower (1.27 vs 3.5; p<0.001) in syphilis reinfections than in first infections. The TPPA increased ≥fourfold in >92.3% of reinfected patients.

Conclusions

Our data highlight the paramount importance of regularly screening patients at risk as syphilis reinfections in men living with HIV are more likely to be latent infections, that is, without symptoms. As non-treponemal tests might be biologically false-positive (up to a titre of 1:8) due to various conditions, a ≥fourfold increase of the TPPA might be considered as optional criterion for the diagnosis of syphilis reinfections. This could be especially valuable for diagnosing reinfected latent stage patients.
Hepatoprotective effect of trypsin/chymotrypsin against olanzapine-induced non-alcoholic steatohepatitis in rats
Authors: Mahmoud Ghada S. , Hosny Ghada , Sayed Sally A.
Published: September 2021

Metabolic side effects of atypical antipsychotics are an important cause of deterioration of cognitive function and failure of drug adherence. The antifatty effect trypsin/chymotrypsin (T/C) and their mechanisms of action remain unclear. To investigate possible therapeutic effect of T/C in rat model of chronic olanzapine (OLZ) – induced hepatic steatosis. Twenty rats were divided into two groups: control (C), given distilled water, and O, given 1 mg/kg of OLZ orally daily for 7 weeks. Then, both groups were given T/C 3 enzyme activity unit (EAU)/kg orally as an add-on treatment daily for the next 5 weeks and were named T/C or T/C+O groups. Rat performance in radial arm water maze was tested twice before and after T/C treatment. We measured liver enzymes, alpha-1 antitrypsin, albumin, total protein, direct and total bilirubin, inflammatory cytokines, and lipoprotein serum levels. Liver samples were collected for histopathology and Ki67 expression. The T/C add-on caused significant reduction in OLZ-induced elevation of alanine transaminase (ALT; P < 0.01), aspartate transaminase (AST; P < 0.001), alkaline phosphatase (ALP; P < 0.05), total cholesterol (Tc; P < 0.01), low-density lipoproteins (LDL-c; P < 0.05), steatosis score (P < 0.001), hepatocyte necrosis (P < 0.01), and significantly increased Ki67 expression (P < 0.01). The T/C add-on to OLZ provided protection against hepatic steatosis, elevated enzymes, and disturbed lipid profile and increased Ki67 without disturbing memory function.
Some finite weighted energy classes of m-subharmonic functions
Authors: Hung Vu Viet , Quy Hoang Nhat
Published: September 2021

Let [Formula: see text] be a bounded [Formula: see text]-hyperconvex domain ([Formula: see text]) and [Formula: see text] be a weighted function. In this paper, we first prove a characterization of the finite weighted energy class [Formula: see text] and give an upper-bound for [Formula: see text]-capacity in the class [Formula: see text]. Then, by using these estimates, we construct some classes of finite weighted energy functions in [Formula: see text]-subharmonic functions class and give some corollaries about the relationship between these finite weighted energy functions classes.
Nonlinear Stability of Equilibrium Points in the Planar Equilateral Restricted Mass-Unequal Four-Body Problem
Authors: Zepeda Ramírez José Alejandro , Alvarez-Ramírez Martha , García Antonio
Published: September 2021

In this paper, we investigate the stability of equilibrium points for the planar restricted equilateral four-body problem in the case that one particle of negligible mass is moving under the Newtonian gravitational attraction of three positive masses [Formula: see text], [Formula: see text] and [Formula: see text] (called primaries). These always lie at the vertices of an equilateral triangle (Lagrangian configuration) and move with constant angular velocity in circular orbits around their center of masses. We consider the case where all the primaries have unequal masses, and investigate the nonlinear stability (in the sense of Lyapunov) of the elliptic equilibrium for the specific values of the mass [Formula: see text] and [Formula: see text] of the primary, fixed on the horizontal axis. Moreover, the [Formula: see text][Formula: see text]:[Formula: see text][Formula: see text] four-order resonant cases are determined and the stability is investigated. In this study, Markeev’s theorem and Arnold’s theorem become key ingredients.