bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission Error in Helical Timing Belt Drives: Case of a Period of Pulley Pitch
Authors: Kagotani Masanori , Ueda Hiroyuki , Koyama Tomio
Published: December 2020

Helical timing belts have been developed in order to reduce the noise that occurs when conventional timing belts are driven. Helical timing belts are characterized by synchronous rotation. Although several studies have been performed to clarify the noise characteristics and belt life of helical timing belts, the transmission error of these belts remains unclear. In the present study, the transmission error having a period of one pitch of the pulley was investigated both theoretically and experimentally for helical timing belt drives. Experimental conditions were such that the transmission force acts on the helical timing belts under quasi-static conditions and the belt incurs belt climbing at the beginning of meshing and at the end of meshing. Experimental results obtained for the transmission error agreed closely with the computed results. The computed results revealed that helical timing belts can be analyzed as a set of very narrow belts for which the helix angle is zero. The transmission error was found to decrease when the helix angle or the belt width increases within a range defined such that the face advance is less than one belt pitch. In addition, there exists an appropriate installation tension that reduces the transmission error.
Finish Roll Forming of Spur Gears for High Efficiency
Authors: Uematsu Seizo , Kato Masana
Published: December 2020

Finish roll forming under the constant center distance by forced feed of tool can be conceived as a method of eliminating errors in conventional form rolling under constant loads. This method generates a high-precision tooth profile by low-speed form rolling when a high rigid screw or cam is used as loading parts. In this study, the high-speed rolling conditions of this method for necessary to be applied in practical situations are discussed. The following conclusions are obtained. When the following design data are given (module, number of teeth, addendum modification coefficient, prescribed design precision, and material characteristics), the accuracy of rolled gear can be predicted from the relationship between the required feed for the tool and the theoretically calculated plastic deformation on the tooth profile. These conclusions are verified experimentally. For example, the tooth accuracy of rolled gears with module 5 can improve from JIS class 3 to JIS class 0 or 1 when the load Fmax is 4 to 5kN and the pitch line velocity is 7 m/min.
Application of the GWPS for Machining of a Transmission Housing
Authors: Rao Suren B. , Neal Gary L. , DeMeter Edward C. , Trethewey Martin W.
Published: December 2020

One component of a modern machining system that has remained virtually unchanged, since time immemorial, is part location. The fundamental basis of current methods of part location is the concept of a physical datum surface, which is created in the first machining operation and conducting all the further machining operations with reference to this physical surface. Current workpiece positioning practice utilizes physical contacts between the fixture and workpiece for location. Due to contact feature variations, the positioning is inconsistent and variable for sequential machining set-ups. Consequently, geometric errors are induced in machined features.

This paper proposes a novel concept, the Global Workpiece Positioning System (GWPS), for datum establishment. Precision artifacts are strategically located on the rough workpiece and a part reference frame is defined, with respect to these artifacts, at a qualification station. This part specific information now travels with the part to the machining station. At the machining station a probe is used to locate the artifacts on the part and determine their location with reference to the machine tool’s reference frame. Since the part reference frame is known with respect to the artifacts, its location can be derived with respect to the machine tool’s reference frame. The part program can then be modified to reflect the actual location of the part and the machining of the features carried out with a greater degree of accuracy and precision. A prototype system using the GWPS concept is implemented and presented. Experimental results validate the GWPS concept. A three-hole pattern is drilled and bored in an aircraft transmission housing component in a two set up operation. The GWPS located workpieces retained a hole center location accuracy within the required drawing specification without the use of the traditional location fixtures that are typically used for the two operational set-ups.
Observation of Ghost Noise on Ground Gears With Vibration Measurement and Detection of Surface Undulation
Authors: Matsumura Shigeki , Houjoh Haruo , Ohshima Shun-ichi , Nagoya Hiroaki
Published: December 2020

In this research, we discuss about the peculiar vibration behavior of a helical gear pair that appears at non-integer order of the meshing frequency. It is supposed that the vibration is generated because of the undulation on tooth surfaces having different cycles of transmission error from tooth mesh cycle. But, it is difficult to detect the undulation with direct measurement of tooth shapes because its amplitude is very small and the length of measured tooth profile is relatively short for spectrum analysis.

At first, characteristics of tooth surface undulation are discussed with spectra of measured gear vibration. It makes clear that there are integer order surface undulation components of gear rotation. Next, possibility of the spectrum analysis of measured tooth surface deviation is also discussed using Maximum Entropy Method.
Optimum Stiffener Layout for the Reduction of Vibration and Noise of Gearbox Housing
Authors: Inoue Katsumi , Yamanaka Masashi , Kihara Masahiko
Published: December 2020

The vibration of gearbox housing causes the structure-borne noise. To reduce the noise as well as vibration, the stiffened plate construction is frequently used for the housing, and the rib stiffener layout is the key to this design. In this paper, the most effective position of stiffeners in reducing the vibration and noise radiation is searched and discussed.

The housing of a simplified single stage gearbox is modeled by triangular finite shell elements. It is excited by a set of harmonic forces which are applied at the bearing positions. The rib stiffener is modeled by beam elements, and its optimum layout is searched by a genetic algorithm. The vibration energy is adopted as the objective function to be minimized in case of the design for low vibration. On the other hand, the radiated sound power is the objective function for low noise. Though the noise is caused by the vibration, the optimum layout of stiffener for low noise is not always identical with the layout for low vibration because of the difference of radiation efficiency. This is numerically-clarified first from the view point of vibration mode of a plate. In case of the design of the gearbox housing concerned, the vibration mode which causes the difference of radiation efficiency is neglected. Consequently, the optimum stiffener is placed along the line from the point of excitation to the fixed point, which reduces the vibration displacement of the faces with bearings.
Contact Pressure Estimates of Tooth Surfaces of Gear Couplings
Authors: Mukoyama Hiroshi , Shimachi Shigeyuki , Hakozaki Yoshihide
Published: December 2020

Recent demands for gear couplings are to reduce the backlash and to increase the shaft angle limit. On coping with these demands, the tooth contact pressure is recognized as the trade-off problem.

In the traditional estimation of tooth contact pressure, the deflection of tooth is calculated by using the formula for spur gear that has long contact bearing in the face width direction, although gear coupling has it in the tooth depth direction. And, the Hertz depression of the tooth surface is estimated as that of the infinite plane. Additionally, the traditional methods don’t consider about the edge contact on the tip or end of tooth.

A successive approximation method is established to find the load distribution on the mating teeth surfaces. As for the effect of the edge contact on the tip or end of tooth, it is cleared that the contact pressure distribution deforms itself severely, but the maximum pressure is almost constant. The expressions estimating the maximum pressure and the displacement of tooth base are constructed for 6 parameters as follows; total load coefficient, relative curvature of teeth surfaces, tooth module, ratio of tooth height to face width, angle of tip contact and deviation of end contact.
A New Development in Continuous Torque Monitoring Couplings
Authors: Corcoran Joe , D’Ercole Steve
Published: December 2020

The use of continuous torque monitoring couplings is quickly becoming an integral part of many predictive maintenance programs in the petrochemical and process industries. More and more operating facilities are using instrumented torque-measuring couplings in order to know how their critical equipment is performing so that the intervals between scheduled shutdowns can be chosen appropriately. This paper will cover a brief history of torquemeters; ie., the basic measuring types which are 1) strain gage types and 2) torsional deflection types. Discussed will be the theories of operation on how they work. Also discussed will be the advances and limitation of these types. Included will be the accuracies that can be obtained by each one and the features and limitation of each. In addition, covered will be a new advance in the mechanical torsional deflection, or phase shift type, which improves the overall design so that mass elastic properties of the coupling with the torque meter are more compatible with high speed turbomachinery.
Study on Load Equilibrating and Vibration Reducing of Three-Ring Gear Reducer
Authors: Li Huamin , Liang Yongsheng , Xin Shaojie
Published: December 2020

A new-style transmission pattern — two stage three-ring gear reducer (TRGR), which eccentric phase difference between middle ring plate and side ring plates is 180° and mass of middle ring plate is twice of that of side ring plate, is put forward in this paper. Analysis of internal gear ring plate inertial force and inertial torque and primary manufacturing and assembling errors that affect on load distribution between ring plates are presented. A new-style load equilibrating mechanism — elastic load equilibrating metal ring (ELEMR) which are placed between bearing outer ring and bearing seat of first input shaft and secondary output shaft is put forward. Experimental studies are performed on load equilibrating and vibrating reducing of original reducer without ELEMR and modified reducer with ELEMR. The experimental result indicates that it’s evident in load equilibrating and vibration reducing effectiveness. Load equilibrating non-uniform coefficient (LDNC) Kp changes form 1.314 of original reducer to 1.073 of modified reducer. Under rated torque and rated speed, radial vibration acceleration of secondary output shaft bearing seat changes from 26.6m/s2 of original reducer to 3.35m/s2 of modified reducer, radial vibration velocity of secondary output-shaft bearing seat change from 9.40mm/s of original reducer to 1.19mm/s of modified reducer.
Thermal Behavior Evaluation During Mechanical Design: Validation of Thermal Numerical Gearbox Models
Authors: Manin Lionel , Play Daniel
Published: December 2020

In todays mechanical design, static and dynamic numerical models are widely used, and thermal models are needed to make robust design. Thermal models, based on the thermal network method, are now available. Several hypotheses are made as physical phenomena are complex and experimental validation is necessary.

A thermal model of gearbox has been already presented and compared to few experimental results that had allowed global validation of the model. Now, the experimental validation is concerned with thermal transient and steady state behavior of gearbox versus transmitted power and lubrication conditions in order to finely validate the model. The test gearbox is compound of 3 spur gears supported by 6 spherical roller bearings, a housing and a lubrication circuit cooled by an oil-air exchanger. The maximum transmitted power is 500 kW. Gears, bearings, housing, shafts, and the lubrication circuit have been equipped with thermocouples, flux-meters and flow-meters. Heat flux were measured on the internal and external side walls of the housing. Oil flowing on a side wall has been measured. Experiments were run under several transmitted powers and oil flows at meshing. Thermal map at steady state and transient temperature rises of technological elements are obtained for each test.

Finally, transient temperature rises and steady state from numerical and experimental results are compared. The comparison shows a good agreement, and the importance of taking into account oil flowing on the inside walls of the housing is brought to the fore. The difficulty of evaluating the oil flowing on the internal walls of a housing is discussed and illustrated with numerical results.
Geometric Non-Linear Influence of a Payload Fairing on Dynamic Displacement Response
Authors: Ramamurti V. , Rajarajan S. , Rao G. V.
Published: December 2020

Finite element method using three noded plate and shell element and 3D beam element in conjunction with mode superposition method is used for studying the large dynamic displacement response of a typical payload fairing due to separation impulse. Incremental technique is used for solving the geometric non-linear problem. Linear formulations are assumed and a step-by-step analysis is performed on the deformed state of each previous time step. The geometry is updated and the stiffness matrix recomputed after every finite time step and the eigenvalue analysis repeated.
Surface Fatigue Strength of Carburized Gear Material for Long Fatigue Lives Based on Reliability Evaluation
Authors: Hsu L. H. , Cheng H. Y. , Hsu K. C.
Published: December 2020

The study used a fatigue test model to investigate the surface fatigue strength of a specific carburized gear material, i.e. AISI 4118. A set of test specimens is designated to simulate the mechanics of gear tooth meshing. A friction, wear, and tribological tester is used to conduct the surface contact stress generated between the test specimens. The surface fatigue lives of the test specimens under different levels of contact stresses have been detected. Based on the maximum likelihood method proposed by Ling and Pan, the R-S-N curves of the surface durability of the specific material have been established using the experimental data of the fatigue test. Especially the fatigue strength for long fatigue lives at required reliability can be estimated.
Influence of Coating Layer to Reduce Thermal Stresses in Cylindrically Formed Metal Matrix Composites
Authors: Okumus Fuat , Turgut Aydin , Sancaktar Erol
Published: December 2020

In this study, the use of coating layers is investigated to reduce thermal stresses in the metal matrix composites which have a mismatch in coefficients of thermal expansions in fiber and matrix components. The thermoelastic solutions are obtained based on a three-cylinder model. It is shown that the effectiveness of the layer can be defined by the product of its coefficient of thermal expansion and thickness. Consequently, a compensating layer with a sufficiently high coefficient of thermal expansion can reduce the thermal stresses in the metal matrix. The study is based on a concentric three cylinder model isolating individual steel fibers surrounded with a coating layer and an aluminum matrix layer. Only monotonic cooling is studied.
Techniques for epitaxial site-selective growth of quantum dots
Authors: McCabe Lauren N. , Zide Joshua M. O.
Published: December 2020

We present an overview of techniques used to pattern the epitaxial growth of quantum dots. Subsequent growth, morphology, and optical characterization are also discussed. The guided assembly of epitaxially grown quantum dots is a research area of great interest in order to enable their use for scalable device applications. The techniques discussed in this review include methods of fabrication and growth, stressor layer growth, alternate materials, theoretical modeling, and device integration.
Fabrication and friction characteristics of arbitrary biosurfaces
Authors: Maddox Shelby R. , Han Xiaoxiao , Meng Xiangbo , Zou Min
Published: December 2020

There are many different types of surfaces found in nature which can increase or reduce friction, such as the well-studied frog toe or lotus leaf. However, methods for replicating these surfaces on a large scale for use in industrial applications are needed in order to take advantage of this natural friction engineering. Most replication processes rely on molding that requires an input surface size comparable to the desired output surface. We present a novel approach of replicating large-scale biosurfaces using a laser scanning confocal microscope for surface digitization and 3D two-photon lithography for the fabrication of the digitized surface. Two different natural surfaces (banana skin and daffodil petal) were replicated. An intermediary tiling process was used to cover a target area of arbitrary size independent of the input texture size. The surfaces were coated with a thin layer of ZnO, and the frictional and wettability characteristics of the replicated surfaces were then examined, demonstrating significant friction reduction up to 42% and increased hydrophobicity due to the presence of texture.
A vertical race up and back down with and without drag
Authors: Mungan Carl E. , Rittenhouse Seth T. , Lipscombe Trevor C.
Published: December 2020

Two identical objects are simultaneously projected vertically upward with the same initial speed in a uniform gravitational field and then return to their starting point. One object is subject to a resistive force proportional to the nth power of its speed where n≥0, such as linear (Stokes) drag for n = 1 or quadratic (Newtonian) drag for n = 2. The other object moves through vacuum with no resistance. Which object returns to its starting point first? It is shown analytically that the object subject to drag always wins the race if n≥1, but that either object can win otherwise, depending on the ratio of the launch speed to the terminal speed of the object subject to drag if 0<n<1 or depending on the ratio of the frictional acceleration to the gravitational acceleration if n = 0. These analytical results are confirmed by Euler–Cromer numerical integration of the equations of motion.
Six textbook mistakes in computational physics
Authors: Gezerlis Alexandros , Williams Martin
Published: December 2020

This article discusses several erroneous claims which appear in textbooks on numerical methods and computational physics. These are not typos or mistakes an individual author has made, but widespread misconceptions. In an attempt to stop these issues from further propagating, we discuss them here, along with some background comments. In each case, we also provide a correction, which is aimed at summarizing material that is known to experts but is frequently mishandled in the introductory literature. To make the mistakes and corrections easy to understand, we bring up specific examples drawn from elementary physics and math. We also take this opportunity to provide pointers to the specialist literature for readers who wish to delve into a given topic in more detail.
An optical n-body gravitational lens analogy
Authors: Selmke Markus
Published: December 2020

Raised menisci around small discs positioned to pull up a water-air interface provide a highly controllable experimental setup capable of reproducing much of the rich phenomenology of gravitational lensing (or microlensing) by n-body clusters. Results are shown for single, binary, and triple mass systems. The scheme represents a versatile testbench for the (astro)physics of general relativity's gravitational lens effects, including high multiplicity imaging of extended sources.
Maternal Physical Activity During Pregnancy and the Effect on the Mother and Newborn: A Systematic Review
Authors: Morales-Suárez-Varela María , Clemente-Bosch Eva , Peraita-Costa Isabel , Llopis-Morales Agustín , Martínez Isabel , Llopis-González Agustín
Published: December 2020

Background: The practice of physical exercise during pregnancy has benefits for both the mother and baby. Currently, there is scientific evidence that supports the inclusion of a monitored physical activity program in the daily activities of pregnant women. The objective of this study is to provide an overview of the current status of the association between physical activity during pregnancy and the effects on the mother and the newborn. Methods: A systematic review of the literature, assessing each study using the Scottish Intercollegiate Guidelines Network, from different databases PubMed, Embase, or ScienceDirect, on the association between maternal physical activity and its effects on the mother and the newborn published from 2010 until 2018 was conducted. Results: About 25 studies were identified and divided into categories according to the health problems affecting the mother or newborn. It was found that 8% of all the studies received a grade B, 68% obtained a grade C, and the remaining 24% obtained less than a grade C. Improved cardiovascular function, decreased risk of gestational diabetes mellitus, hypertension, and the limitation of weight gain are among the benefits to the mother with lower percentage of body fat, increased gestational age, and potentially improved neurodevelopment as benefits for the child. Conclusions: The realization of physical activity during pregnancy is supported by most of the studies reviewed. However, given the vulnerability of the studied populations, more studies on the association between physical activity and pregnancy are necessary.
Metabolites Potentiate Nitrofurans in Nongrowing Escherichia coli
Authors: Aedo Sandra J. , Tang Juechun , Brynildsen Mark P.
Published: December 2020

Nitrofurantoin (NIT) is a broad-spectrum bactericidal antibiotic used in the treatment of urinary tract infections. It is a prodrug that once activated by nitroreductases goes on to inhibit bacterial DNA, RNA, cell wall, and protein synthesis.
In-Tree Behavior of Diverse Viruses Harbored in the Chestnut Blight Fungus,
Cryphonectria parasitica
Authors: Suzuki Nobuhiro , Cornejo Carolina , Aulia Annisa , Shahi Sabitree , Hillman Bradley I. , Rigling Daniel
Published: December 2020

The ascomycete
Cryphonectria parasitica
causes destructive chestnut blight, which is controllable by hypovirulence-conferring viruses infecting the fungus. The tripartite chestnut/
C. parasitica
/virus pathosystem involves the dynamic interactions of their genetic elements, i.e., virus transmission and lateral transfer of nuclear and mitochondrial genomes between fungal strains via anastomosis occurring in trees.
First do no harm: practitioners’ ability to ‘diagnose’ system weaknesses and improve safety is a critical initial step in improving care quality
Authors: English Mike , Ogola Muthoni , Aluvaala Jalemba , Gicheha Edith , Irimu Grace , McKnight Jacob , Vincent Charles A
Published: December 2020

Healthcare systems across the world and especially those in low-resource settings (LRS) are under pressure and one of the first priorities must be to prevent any harm done while trying to deliver care. Health care workers, especially department leaders, need the diagnostic abilities to identify local safety concerns and design actions that benefit their patients. We draw on concepts from the safety sciences that are less well-known than mainstream quality improvement techniques in LRS. We use these to illustrate how to analyse the complex interactions between resources and tools, the organisation of tasks and the norms that may govern behaviours, together with the strengths and vulnerabilities of systems. All interact to influence care and outcomes. To employ these techniques leaders will need to focus on the best attainable standards of care, build trust and shift away from the blame culture that undermines improvement. Health worker education should include development of the technical and relational skills needed to perform these system diagnostic roles. Some safety challenges need leadership from professional associations to provide important resources, peer support and mentorship to sustain safety work.
Changes in demand for emergency ambulances during a nationwide lockdown that resulted in elimination of COVID-19: an observational study from New Zealand
Authors: Dicker Bridget , Swain Andrew , Todd Verity Frances , Tunnage Bronwyn , McConachy Emma , Drake Haydn , Brett Michelle , Spearing Dan , Howie Graham John
Published: December 2020

Objective

To examine the impact of a 5-week national lockdown on ambulance service demand during the COVID-19 pandemic in New Zealand.

Design

A descriptive cross-sectional, observational study.

Setting

High-quality data from ambulance electronic clinical records, New Zealand.

Participants

Ambulance records were obtained from 588 690 attendances during pre-lockdown (prior to 17 February 2020) and from 36 238 records during the lockdown period (23 March to 26 April 2020).

Main outcome measures

Ambulance service utilisation during lockdown was compared with pre-lockdown: (a) descriptive analyses of ambulance events and proportions of event types for each period, (b) absolute rates of ambulance attendance (event types/week) for each period.

Results

During lockdown, ambulance patients were more likely to be attended at home and less likely to be aged between 16 and 25 years. There was a significant increase in the proportion of lower acuity patients (Status 3 and Status 4) attended (p<0.001) and a corresponding increase in patients not transported from scene (p<0.001). Road traffic crashes (p<0.001) and alcohol-related incidents (p<0.001) significantly decreased. There was a decrease in the absolute number of weekly ambulance attendances (ratio (95% CI), 0.89 (0.87 to 0.91), p<0.001), attendances to respiratory conditions (0.74 (0.61 to 0.86), p=0.01), and trauma (0.81 (0.77 to 0.85), p<0.001). However, there was a significant increase in ambulance attendances for mental health conditions (1.37 (1.22 to 1.51), p=0.005).

Conclusions

Despite the relative absence of COVID-19 in the community during the 5-week nationwide lockdown, there were significant differences in ambulance utilisation during this period. The lockdown was associated with an increase in ambulance attendances for mental health conditions and is of concern. In considering future lockdowns, the potential implications on a population’s mental well-being will need to be seriously considered against the benefits of elimination of virus transmission.
Effectiveness of chest pain centre accreditation on the management of acute coronary syndrome: a retrospective study using a national database
Authors: Sun Pengfei , Li Jianping , Fang Weiyi , Su Xi , Yu Bo , Wang Yan , Li Chunjie , Chen Hu , Wang Xingang , Zhang Bin , Li Yuxi , Momin Mohetaboer , Shi Ying , Wang Haibo , Zhang Yan , Xiang Dingcheng , Huo Yong
Published: December 2020

Background

Large-scale real-world data to evaluate the impact of chest pain centre (CPC) accreditation on acute coronary syndrome (ACS) emergency care in heavy-burden developing countries like China are rare.

Methods

This study is a retrospective study based on data from the Hospital Quality Monitoring System (HQMS) database. This study included emergency patients admitted with ACS to hospitals that uploaded clinical data continuously to the database from 2013 to 2016. Propensity score matching was used to compare hospitals with and without CPC accreditation during this period. A longitudinal self-contrast comparison design with mixed-effects models was used to compare management of ACS before and after accreditation.

Results

A total of 798 008 patients with ACS from 746 hospitals were included in the analysis. After matching admission date, hospital levels and types and adjusting for possible covariates, patients with ACS admitted to accredited CPCs had lower in-hospital mortality (OR=0.70, 95% CI 0.53 to 0.93), shorter length of stay (LOS; adjusted
multiplicative effect=0.89, 95% CI 0.84 to 0.94) and more percutaneous coronary intervention (PCI) procedures (OR=3.53, 95% CI 2.20 to 5.66) than patients admitted in hospitals without applying for CPC accreditation. Furthermore, when compared with the ‘before accreditation’ group only in accredited CPCs, the in-hospital mortality and LOS decreased and the usage of PCI were increased in both ‘accreditation’ (for in-hospital mortality: OR=0.86, 95% CI 0.79 to 0.93; for LOS: 0.94, 95% CI 0.93 to 0.95; for PCI: OR=1.22, 95% CI 1.18 to 1.26) and ‘after accreditation’ groups (for in-hospital mortality: OR=0.90, 95% CI 0.84 to 0.97; for LOS: 0.89, 95% CI 0.89 to 0.90; for PCI: OR=1.36, 95% CI 1.33 to 1.39). The significant benefits of decreased in-hospital mortality, reduced LOS and increased PCI usage were also observed for patients with acute myocardial infarction.

Conclusions

CPC accreditation is associated with better management and in-hospital clinical outcomes of patients with ACS. CPC establishment and accreditation should be promoted and implemented in countries with high levels of ACS.
Accessing abortion outside jurisdiction following legalisation of abortion in the Republic of Ireland
Authors: Bras Sierou , Gomperts Rebecca , Kelly Michaela , Aiken Abigail R A , Conlon Catherine
Published: December 2020

Background

After having one of the most restrictive abortion laws worldwide, Ireland legalised abortion in January 2019. We examine how legalisation impacted on demand for online telemedicine outside the jurisdiction.

Methods

We analysed anonymised data from 534 people from Ireland seeking online telemedicine abortion prior to legalisation (January–March and October–December 2018) and in the first 3 months following legalisation (January–March 2019). Numbers, characteristics and reasons for seeking the service before and after legalisation were compared. Content analysis of emails from people seeking the service following legalisation explored reasons for seeking care.

Results

Half as many people contacted Women on Web in the 3 months immediately after legalisation as compared with contacts 12 months prior (103 vs 221). Of these, the proportion receiving the service reduced, from 72% prior to legalisation to 26% after legalisation (p≤0.001). After legalisation, access related reasons for seeking online telemedicine featured less while reasons relating to privacy, stigma and avoiding protestors featured more.

Conclusions

People continued to seek abortion through online telemedicine after legalisation, though the number of contacts reduced by half and the proportion receiving the service decreased considerably. To address access issues, policy measures should promote normalisation of abortion, legislate for safe zones around providers, and consider access in situations of coercive control or abuse including the role of telemedicine in the local model of care. Abortion provided through online telemedicine continues to be an important part of providing safe, accessible abortion even after legalisation.
The influence of proton pump inhibitor therapy on the outcome of infliximab therapy in inflammatory bowel disease: a patient-level meta-analysis of randomised controlled studies
Authors: Lu Thomas X , Dapas Matthew , Lin Erika , Peters Trevor , Sakuraba Atsushi
Published: December 2020

Objective

In treating patients with inflammatory bowel disease (IBD), how concomitant medications influence the response to infliximab is largely unexplored. We aim to evaluate whether proton pump inhibitors (PPIs) affect the response to infliximab therapy in patients with IBD.

Design

Patient-level data of adult patients with moderate-to-severe IBD treated with infliximab were obtained from the Yale Open Data Access Framework. Multivariable analysis and propensity score-matched analysis were performed to assess week 30 remission rates, week 54 remission rates and hospitalisation rates in patients on infliximab therapy with and without PPI exposure.

Results

Among the five randomised controlled studies, there were 147 and 889 patients on infliximab with and without PPI therapy, respectively. Patients on PPI were older, more likely to be Caucasian and were less likely to be on immunomodulator therapy. Patients on PPI were significantly less likely to achieve week 30 remission on multivariable analysis (OR 0.45, p<0.001). Following propensity score matching adjusting for baseline difference in patient characteristics, the week 30 remission rates were 30% and 49% in patients with and without PPI therapy, respectively (p<0.001). Analysing separately for disease, the findings remained statistically significant in Crohn’s disease but did not reach significance in UC. Similar results were seen with week 54 remission rates. Patients on PPI were also more likely to be hospitalised (15% vs 8%, p=0.007). Rates of adverse events such as gastroenteritis were not different between the two groups.

Conclusion

In this patient-level meta-analysis of randomised controlled studies, we found that patients with IBD taking PPI were less likely to achieve remission while on infliximab therapy. The results of our study warrant further investigation into the effect of PPI on IBD outcomes and therapies.
Treating and controlling digital dermatitis in dairy cattle
Authors: Bell Nick , Vanhoudt Arne
Published: December 2020

Background

Digital dermatitis (DD) is one of the main causes of lameness in dairy cattle, and is prevalent in most dairy herds worldwide and is of major welfare and economic significance.

Aim of the article

This article focuses on current concepts of DD treatment and control strategies, but will not go into detail about most concepts relating to prevention – namely biosecurity, improving foot hygiene, nutrition and genetics. The article includes concepts related to disease screening, treatment at both an individual cow level and with footbaths, and the control of DD through foot disinfection using footbaths. Readers are referred to other detailed reviews where appropriate, such as Plummer and Krull (2017) and Orsel and others (2018).
Landscape of natural killer cell activity in head and neck squamous cell carcinoma
Authors: Charap Andrew J , Enokida Tomohiro , Brody Rachel , Sfakianos John , Miles Brett , Bhardwaj Nina , Horowitz Amir
Published: December 2020

Head and neck squamous cell carcinoma (HNSCC) encompasses a set of cancers arising from the epithelia of the upper aerodigestive tract, accounting for a significant burden of disease worldwide due to the disease’s mortality, morbidity, and predilection for recurrence. Prognosis of HNSCC in the recurrent and/or metastatic (R/M-HNSCC) setting is especially poor and effective treatment options increasingly rely on modulating T-cell antitumor responses. Still, immunotherapy response rates are generally low, prompting the exploration of novel strategies that incorporate other effector cells within the tumor microenvironment. Within the last decade, important advances have been made leveraging the powerful innate antitumor function of natural killer (NK) cells to treat solid tumors, including head and neck squamous cell carcinoma. NK cells are hybrid innate-adaptive effector cells capable of directly eliminating tumor cells in addition to initiating adaptive antitumor immune responses. In the setting of HNSCC, NK cells are important for tumor surveillance and control, and NK cell infiltration has repeatedly been associated with a favorable prognosis. Yet, HNSCC-infiltrating NK cells are susceptible to an array of immune evasion strategies employed by tumors that must be overcome to fully realize the antitumor potential of NK cells. We believe that a conceptual framework informed by the basic biological understanding of the mechanisms underlying NK cell activation can improve treatment of HNSCC, in part by selecting for patients most likely to respond to NK cell-based immunotherapy. Herein, we review the activity of NK cells in HNSCC, paying special attention to the role of environmental and genetic determinants of NK cell antitumor function. Moreover, we explore the evidence that NK cells are a crucial determinant of the efficacy of both established and emerging treatments for HNSCC.
Physician leadership during the COVID-19 pandemic: an emphasis on the team, well-being and leadership reasoning
Authors: Standiford Taylor C. , Davuluri Kavya , Trupiano Nicole , Portney David , Gruppen Larry , Vinson Alexandra H.
Published: December 2020

Background

The COVID-19 pandemic impacted many aspects of normal operations in academic medicine. While effective leadership is always important, the intensity and urgency of COVID-19 challenged academic medicine leaders to find new ways to lead their institutions and manage their own experiences of the pandemic.

Methods

Sixteen physician leaders from Michigan Medicine took part in semistructured interviews during April and May 2020. Participants were asked open-ended questions about the attributes and techniques that were important to effectively lead during a crisis. The authors analysed the interviews using thematic analysis.

Results

Participants described three overarching themes of leadership during the COVID-19 pandemic: (1) bringing together a diverse team with clear, shared goals; (2) using a range of strategies to tend to their teams’—as well as their own—well-being; and (3) engaging in leadership reasoning as a way of learning from others and reflecting on their own actions to inform their future leadership practice.

Conclusion

The results of this study reveal several salient themes of crisis leadership during the COVID-19 pandemic. The findings also highlight the role of leadership reasoning, a reflective practice employed by leaders to understand and improve their leadership skills. This finding presents leadership skill development as part of lifelong learning in medicine. Findings may be incorporated into best practices and preparations to inform future healthcare leaders.
High-resolution scanning electron microscopy for the analysis of three-dimensional ultrastructure of clots in acute ischemic stroke
Authors: Mereuta Oana Madalina , Fitzgerald Seán , Christensen Trace A , Jaspersen Adam L , Dai Daying , Abbasi Mehdi , Puttappa Tejaswini , Kadirvel Ram , Kallmes David F , Doyle Karen M , Brinjikji Waleed
Published: December 2020

Background

Characterization of acute ischemic stroke (AIS) clots has typically focused on two-dimensional histological analysis of the thrombus. The three-dimensional (3D) architecture and distribution of components within emboli have not been fully investigated. The aim of this study was to examine the composition and microstructure of AIS clots using histology and serial block-face scanning electron microscopy (SBFSEM).

Methods

As part of the multi-institutional STRIP registry, 10 consecutive AIS emboli were collected from 10 patients treated by mechanical thrombectomy. Histological and immunohistochemical analysis was performed to determine clot composition. SBFSEM was used to assess the ultrastructural organization of the clots and specific features of individual components.

Results

Quantification of Martius Scarlett Blue stain identified fibrin (44.4%) and red blood cells (RBCs, 32.6%) as the main components. Immunohistochemistry showed a mean platelet and von Willebrand factor content of 23.9% and 11.8%, respectively. The 3D organization of emboli varied greatly depending on the region analyzed. RBC-rich areas were composed mainly of tightly packed RBCs deformed into polyhedrocytes with scant fibrin fibers interwoven between cells. The regions with mixed composition showed thick fibrin fibers along with platelets, white blood cells and RBC clusters. Fibrin-rich areas contained dense fibrin masses with sparse RBC. In three cases, the fibrin formed a grid-like or a sponge-like pattern, likely due to thrombolytic treatment. Segmentation showed that fibrin fibers were thinner and less densely packed in these cases.

Conclusions

3D-SEM provides novel and potentially clinically relevant information on clot components and ultrastructure which may help to inform thrombolytic treatment and medical device design.
Impact of eloquent motor cortex-tissue reperfusion beyond the traditional thrombolysis in cerebral infarction (TICI) scoring after thrombectomy
Authors: Raychev Radoslav , Saber Hamidreza , Saver Jeffrey L , Hinman Jason D , Brown Scott , Vinuela Fernando , Duckwiler Gary , Jahan Reza , Tateshima Satoshi , Szeder Viktor , Nour May , Colby Geoffrey P , Restrepo Lucas , Kim Doojin , Bahr-Hosseini Mersedeh , Ali Latisha , Starkman Sidney , Rao Neal , Nogueira Raul G , Liebeskind David
Published: December 2020

Background

Targeted eloquence-based tissue reperfusion within the primary motor cortex may have a differential effect on disability as compared with traditional volume-based (thrombolysis in cerebral infarction, TICI) reperfusion after endovascular thrombectomy (EVT) in the setting of acute ischemic stroke (AIS).

Methods

We explored the impact of eloquent reperfusion (ER) within primary motor cortex (PMC) on clinical outcome (modified Rankin Scale, mRS) in AIS patients undergoing EVT. ER-PMC was defined as presence of flow on final digital subtraction angiography (DSA) within four main cortical branches, supplying the PMC (middle cerebral artery (MCA) – precentral, central, postcentral; anterior cerebral artery (ACA) – medial frontal branch arising from callosomarginal or pericallosal arteries) and graded as absent (0), partial (1), and complete (2). Prospectively collected data from two centers were analyzed. Multivariate analysis was conducted to assess the impact of ER-PMC on 90-day disability (mRS) among patients with anterior circulation occlusion who achieved partial reperfusion (TICI 2a and 2b).

Results

Among the 125 patients who met the study criteria, ER-PMC distribution was: absent (0) in 19/125 (15.2%); partial (1) in 52/125 (41.6%), and complete (2) in 54/125 (43.2%). TICI 2b was achieved in 102/125 (81.6%) and ER-PMC was substantially higher in those patients (P<0.001). In multivariate analysis, in addition to age and symptomatic intracranial hemorrhage, ER-PMC had a profound independent impact on 90-day disability (OR 6.10, P=0.001 for ER-PMC 1 vs 0 and OR 9.87, P<0.001 for ER-PMC 2 vs 0), while the extent of total partial reperfusion (TICI 2b vs 2a) was not related to 90-day mRS.

Conclusions

Eloquent PMC-tissue reperfusion is a key determinant of functional outcome, with a greater impact than volume-based (TICI) degree of partial reperfusion alone. PMC-targeted revascularization among patients with partial reperfusion may further diminish post-stroke disability after EVT.
Immediate post-operative aneurysm occlusion after endovascular treatment of intracranial aneurysms with coiling or balloon-assisted coiling in a prospective multicenter cohort of 1189 patients: Analysis of Recanalization after Endovascular Treatment of intracranial Aneurysm (ARETA) Study
Authors: Pierot Laurent , Barbe Coralie , Herbreteau Denis , Gauvrit Jean-Yves , Januel Anne-Christine , Bala Fouzi , Ricolfi Frédéric , Desal Hubert , Velasco Stéphane , Aggour Mohamed , Chabert Emmanuel , Sedat Jacques , Trystram Denis , Marnat Gaultier , Gallas Sophie , Rodesch Georges , Clarençon Frédéric , Papagiannaki Chrysanthi , White Phil , Spelle Laurent
Published: December 2020

Background

Coiling, including balloon-assisted coiling (BAC), is the first-line therapy for ruptured and unruptured aneurysms. Its efficacy can be clinically evaluated by bleeding/rebleeding rate after coiling, and anatomically evaluated by aneurysm occlusion post-procedure and during follow-up. We aimed to analyze immediate post-coiling aneurysm occlusion and associated factors within the Analysis of Recanalization after Endovascular Treatment of intracranial Aneurysm (ARETA) population.

Methods

Between December 2013 and May 2015, 16 neurointerventional departments prospectively enrolled participants treated for ruptured and unruptured aneurysms (ClinicalTrials.gov:NCT01942512). Participant demographics, aneurysm characteristics, and endovascular techniques were recorded. In patients with aneurysms treated by coiling or BAC, immediate post-operative aneurysm occlusion was independently evaluated by a core lab using a 3-grade scale: complete occlusion, neck remnant, and aneurysm remnant.

Results

Of 1135 participants (age 53.8±12.8 years, 754 women (66.4%)), 1189 aneurysms were analyzed. Treatment modality was standard coiling in 645/1189 aneurysms (54.2%) and BAC in 544/1189 (45.8%). Immediate post-operative aneurysm occlusion was complete occlusion in 57.8%, neck remnant in 34.4%, and aneurysm remnant in 7.8%. Adequate occlusion (complete occlusion or neck remnant) was significantly more frequent in aneurysms with size <10 mm (93.1% vs 86.3%; OR 1.8, 95% CI 1.1 to 3.2; p=0.02) and in aneurysms with a narrow neck (95.8% vs 89.6%; OR 2.5, 95% CI 1.5 to 4.1; p=0.0004). Patients aged <70 years had significantly more adequate occlusion (92.7% vs 87.2%; OR 1.9, 95% CI 1.1 to 3.4; p=0.04).

Conclusions

Immediately after aneurysm coiling, including BAC, adequate aneurysm occlusion was obtained in 92.2%. Age <70 years, aneurysm size <10 mm, and narrow neck were factors associated with adequate occlusion.

Trial registration number

NCT01942512,http://www.clinicaltrials.gov.
Evidence supporting the standardisation of extragenital gonorrhoea and chlamydia screenings for women
Authors: Jann Jamieson Trevor , Cunningham Nicole J , Assaf Ryan D , Bolan Robert K
Published: December 2020

Objective

Current guidelines for women do not include extragenital screening forChlamydia trachomatis(CT) andNeisseria gonorrhoeae(NG) and do not mention anal sex behaviour. The objective of this cross-sectional study was to determine the number of potentially missed CT and NG cases by relying on urogenital screening and self-reported anal sex behaviour among women.

Methods

Demographic and clinical data of 4658 women attending a community health centre in Los Angeles, California, USA from 2015 to 2018 were examined. CT and NG were detected using nucleic acid amplification test (APTIMA Combo 2, Hologic Gen-Probe, San Diego, California). Demographic and behavioural factors were also examined to assess potentially missed NG/CT cases. Multivariable regression analyses were used to determine whether reported anal sex behaviour predicts NG/CT rectal infection.

Results

A total of 193 NG cases and 552 CT cases were identified; however, 53.9% of NG cases and 25.5% of CT cases were identified exclusively through extragenital screening. Of all positive cases of rectal CT, 87.0% did not report anal sex without a condom and 91.3% did not report any anal sex with their last sexual partner. Of all positive cases of rectal NG, 78.9% did not report anal sex without a condom and 76.3% did not report any anal sex with their last sexual partner. Anal sex with last partner was not predictive of NG/CT rectal infection.

Conclusions

Relying solely on urogenital screening and reported behaviour misses NG/CT cases. Extragenital NG/CT screening should be conducted in all women regardless of reported anal sex behaviour.