bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Recovery Factors and Friction Coefficients for Supersonic Flow of Air in a Tube: 1—Apparatus, Data, and Results Based on a Simple One-Dimensional Flow Model
Authors: Kaye J. , Keenan J. H. , Klingensmith K. K. , Ketchum G. M. , Toong T. Y.
Published: April 2021

For the past few years a program has been under way to obtain reliable data on the rate of heat transfer to air moving at supersonic speeds. The investigation was limited to air flowing at supersonic speeds in a round tube. The program was divided into two separate parts, the first for measurement of the adiabatic wall temperatures of a supersonic stream and the second for the heat-transfer rate. The first part of this program is described here. The details of three experimental test combinations used to measure the adiabatic wall temperature and local state of a supersonic stream of air are presented. The experimental data for forty runs, in the form of measured pressure and temperature distributions, are included. The range of diameter Reynolds number covered is from 0.15 × 105 to 5 × 105. The length Reynolds number extends to 120 × 105. The Mach number at the inlet to the round tube is about 2.6. The calculated quantities such as the local apparent friction coefficient, recovery factor, local Mach number, and so forth, are obtained from the simple one-dimensional flow model for which the properties of the stream are uniform at any cross section of the tube and boundary-layer effects are ignored. A subsequent paper deals with the calculation of these quantities when account is taken of the boundary-layer growth in the tube on the basis of a two-dimensional flow model.
The Theoretical Analysis of Metal-Forming Problems in Plane Strain
Authors: Lee E. H.
Published: April 2021

The plastic flow in plane strain of an ideally plastic material subjected to large strains is considered. Elastic strains are negligible and a rigid-plastic type of analysis is adopted. The equations to be satisfied are detailed, and they include stress and velocity equations in the plastic regions, as well as consideration of the stress field in the rigid regions to check the validity of small strains there. Complete solutions satisfying these conditions require the determination of the rigid-plastic boundaries to delineate the regions in which the various conditions must be satisfied. The fallacy of static determinacy of such problems in terms of the stress equations only is emphasized. The study of complete solutions indicates errors in solutions commonly accepted in the literature which are based on the stress equations only. Examples are discussed. The general occurrence of velocities in the boundary conditions of forming problems is pointed out, and the difficulty of setting such problems in terms of boundary stresses only is illustrated by examples.
Partially Plastic Thick-Walled Cylinder Theory
Authors: Steele M. C.
Published: April 2021

Previous theories for partially plastic thick-walled cylinders under internal pressure are reviewed. A quantitative comparison is given for (a) compressibility versus incompressibility of material, and (b) von Mises’ versus Tresca’s theory of failure. The former reveals that deflections at the outside and bore surfaces agree closely, although considerable percentage differences may be found in the axial stresses and strains. Large differences (except for the axial stress) are found in comparing the two theories of failure. Based on the comparison and available experimental evidence, a theory is presented in closed form to include the Hencky stress-strain relations, incompressibility, and Ludwik’s strain-hardening function.
Heat-Exchanger Tube-Sheet Design—2: Fixed Tube Sheets
Authors: Gardner K. A.
Published: April 2021

It is shown that “fixed” tube sheets may be designed in exactly the same manner as “floating” tube sheets with the same boundary restraint, provided that a fictitious uniform “equivalent design pressure” is used in the calculations instead of the actual hydrostatic pressure. This equivalent pressure is evaluated in terms of tube-side pressure, shell-side pressure, differential thermal expansion, and the condition of boundary restraint. The design factors for all tube sheets presented in an earlier paper are shown to be well represented by very simple expressions when the fundamental design parameter xa becomes large.
Lateral Vibrations as Related to Structural Stability
Authors: Lurie Harold
Published: April 2021

The apparently different physical problems of lateral vibration and elastic stability are limiting cases of a single phenomenon, the more general expression being the mode of vibration with end thrust. It is shown that the square of the frequency of lateral vibration is approximately linearly related to the end load. The linear relationship is exact if the mode of free vibrations is identical to the buckling mode. In all cases, the load corresponding to zero frequency is the critical buckling load. Experimental tests were conducted on elastically restrained columns in the form of rigid rectangular frames. It was found that the relationship between the square of the frequency and the load is practically linear, and that the extrapolated load corresponding to zero frequency coincides with the buckling load. Rigid-joint trusses also were tested. In some cases the relationship between the square of the frequency and the load deviates considerably from linearity, but the approximate buckling load can be predicted. In the case of thin flat plates, tests showed that the buckling load cannot be predicted from vibration tests in practice. It is indicated that this is probably because the linear plate equations are not valid owing to initial curvatures in the plate.
Bending Vibrations of a Pipe Line Containing Flowing Fluid
Authors: Housner G. W.
Published: April 2021

Both free vibrations and forced motions due to crosswinds may create important problems in the design of pipe lines supported above ground. An analytic investigation, based on simple beam theory, shows that the flow of fluid in such a pipe line has no beneficial effect upon the vibrations. The fluid velocity causes a dynamic coupling of the simple modes of vibration so that the normal modes of vibration are of complex shape with 90-deg out-of-phase components. The solution is presented for free vibrations and for steady-state forced vibrations, and it is shown that large amplitudes may be developed if the amount of damping is too small. It is shown that at low fluid velocities there is negligible effect upon the vibration of the pipe line, and at a certain high critical velocity the fluid flow causes a dynamic instability. The present analysis revises the conclusions which appeared in an earlier publication.
The Computation of Flexural–Torsional Buckling Loads
Authors: Michielsen H. F.
Published: April 2021

Solution by ordinary means of the cubic equation for the torsional buckling load, first derived by Kappus, often leads to insufficiently accurate results. A method is presented which avoids the loss of accuracy involved. The procedure is straightforward and no graphical means are involved. However, one formula is to be solved by trial and error.
Analysis of Elastic Two and Three-Section Short Columns
Authors: Tyler C. M. , Lee F. Z.
Published: April 2021

Short columns subjected to repeated loading or in which permanent deformation is not permissible should be designed on the basis of maximum fiber stress. This stress may vary considerably in apparently identical columns owing to small inaccuracies of shape and application of load. The effects of all probable deviations of both column and load can be represented by an “equivalent eccentricity of loading” or by an “equivalent curvature of the column” (1, 2). These equivalents are so chosen that calculated fiber stresses will equal the maximum probable stress encountered in the actual column. In the paper, analytical formulas in terms of equivalent eccentricity are developed for two and three-section short columns. These may be considered as extensions of the secant column formula (3) to more complicated shapes. Specific numerical examples of sectional short columns may be analyzed by a relaxation method (4). Sectional long columns have been treated by Thompson (5) and Radomski (6).
Optimum Single Propellers in Radially Varying, Incompressible Inflow
Authors: Lane Frank
Published: April 2021

The Betz process for minimizing the energy loss of single propellers is extended to the propeller operating in radially varying inflow, with a view toward the development of optimum stern propulsion for bodies of revolution. Assuming the usual lifting-line treatment of the propeller blades, an application of the isoperimetric problem in the calculus of variations is directed toward minimizing the energy loss while maintaining constant total thrust. Resulting expressions describe the optimum radial distribution of induced velocity in terms of an undetermined multiplier. The magnitude of the required total thrust, in turn, fixes the value of this multiplier, making the solution determinate. Inclusion of blade-profile drag at a later point in the development serves to determine an optimum propeller diameter for minimum over-all energy loss. The method gains in accuracy as the ratio of blade number to advance ratio increases, due to an approximation in the relation between the circulation and induced velocity.
Experiments on the Plastic Compression of a Block Between Rough Plates
Authors: Nye J. F.
Published: April 2021

Hill, Lee, and Tupper have recently published a theory for the plastic compression of a block between parallel plates. This paper describes experiments designed to check the theory as closely as possible. The theoretical predictions for the average pressure on the plates are very well verified by the experiments. The details of the strain distribution within the block and the positions of the elastic-plastic boundaries are closely compared with the theory.
The Plane-Stress Problem of Perforated Plates
Authors: Horvay G.
Published: April 2021

In an earlier paper it was indicated that perforated plates of triangular layout, with narrow ligaments, as they occur, for instance, in heat-exchanger tube sheets, can be treated in plane-stress calculations as solid sheets of suitable elastic moduli, provided that the stress distribution does not vary appreciably from hole to hole. This paper completes that study by providing suitable curves (Figs. 4, 8), from which deformations and stresses can be read off in terms of the values calculated for solid sheets, for mechanical, thermal, and gravitational loads.
Temperature Development in a Heated Contact With Application to Sliding Contacts
Authors: Holm Ragnar
Published: April 2021

The calculation of the development of the temperature in and around a heated contact is reduced to the use of some simple formulas for certain fundamental variables and to making readings from a diagram. Applications are made to a contact that is heated by the current and to circular or oval heat sources (for example, friction-heated sliding contact-surfaces) stationary or moving on the face of a semi-infinite body. The practicability of the method is due primarily to the fact that the numerical calculations, which are made before using the standard curves, are so simple that the chance of a numerical error is very small.
A Mathematical Analysis of the Relaxation Type of Vehicle Suspension
Authors: Gallagher Joseph , Volterra Enrico
Published: April 2021

The responses of the relaxation type of vehicle suspension to steady and transient disturbances are analyzed. The results are compared with the corresponding responses for the standard type of vehicle suspension. The relaxation suspension system shows a definite improvement over the standard suspension system in the response to transient disturbances, as the initial shocks following a sudden wheel movement are reduced greatly. In the particular case of critical adjustment of a relaxation suspension system the maximum amplitude of the transient vibration is approximately 30 per cent lower than that of the standard-type system at critical adjustment. The amplitude and phase-angle curves presented in the paper for the steady-state motion, together with the transient-state-response analysis, permit the design of a relaxation-type suspension system with known vibrational characteristics in both states.
Pressure Drops in the Pneumatic Conveyance of Solids
Authors: Pinkus Oscar
Published: April 2021

With the object of studying the characteristics of the horizontal flow of a mixture of solids and air a theoretical analysis of the flow pattern was attempted. Experiments were performed whose object was to determine the relationship between pressure loss, solids flow rate, and air velocity, and to obtain values for the frictional constants involved in the analysis. A justification for the developed equations was sought. It was found that the presence of the solid phase causes an appreciable pressure loss which is a linear function of both solid and gas flow rate. This justified the theoretical equations which predicted such a relationship. Experiments with two sizes of the same sand showed a higher pressure drop for the larger particles, other conditions being equal. These experiments, however, question the validity of applying the Fanning equation to a solid phase. The equation holds for a given solid but does not take into account variations in its size. The introduction of the dimensionless group d/D is proposed. On the basis of this investigation, it is concluded that the drag coefficient C is a function of the Reynolds number. The ratio of solids velocity to gas velocity is 0.5–0.6 for the small and 0.3 for the large sand. Following results of this work it would seem desirable to operate pneumatic systems at low gas velocities and high solid rates. Recommendations for further investigations are made.
Parameter Identification for Electrochemical Models of Lithium-Ion Batteries Using Sensitivity Analysis
Authors: Dangwal Chitra , Canova Marcello
Published: April 2021

Predicting the chemical and physical processes occurring in Lithium-ion cells with high-fidelity electrochemical models is today a critical requirement to accelerate the design and optimization of battery packs for automotive and aerospace applications. One of the common issues associated with electrochemical models is the complexity of parameter identification, particularly when relying only on experimental data obtained via non-invasive techniques. This paper presents a novel approach to improve the common methods of parameter calibration that consists of matching the predicted terminal voltage to test data via optimization methods. The study is conducted for an nickel-manganese-cobalt (NMC)-graphite cell, modeled using a reduced-order Extended Single Particle Model (ESPM). The proposed approach relies on using a large-scale particle swarm optimization (PSO), modified by including a term that accounts for the parameter sensitivity information, such that the rate of convergence and robustness of the algorithm to obtain a consistent solution in the presence of uncertainties in the initial conditions are significantly improved.
Ultrathin and Porous NiCo2O4 Nanosheet-Based Three-Dimensional Hierarchical Electrode Materials for High-Performance Asymmetric Supercapacitor
Authors: Ren Fuyong , Tong Zhixiang , Tan Shufen , Yao Junnan , Pei Lijun , Ji Yajun , Abulizi Abulikemu
Published: April 2021

It is well known that designing unique morphology and the structure of electrode materials is an effective strategy to achieve high-performance supercapacitors (SC). Herein, the ultrathin and porous NiCo2O4 nanosheet-based three-dimensional (3D) hierarchical electrode materials were synthesized via a simple and cost-effective solvothermal method and subsequent annealing process. Since the ultrathin and porous nanosheets could accelerate the transmission of ions and provide numerous active sites, the obtained NiCo2O4 nanosheet-based electrode exhibited great electrochemical performance with a high area capacity of 5.38 F/cm2 (2690 F/g1) at a current density of 10 mA/cm2 and good rate performance of 41% capacitance retention at 50 mA/cm2. Furthermore, the corresponding asymmetry supercapacitor was assembled by using the resulted NiCo2O4 nanosheets and active carbon as a positive electrode and a negative electrode, respectively. As expected, the corresponding supercapacitor delivered a superior energy density of 52.6 Wh/kg at a power density of 1.1 kW/kg and extraordinary capacitive retention of 80.9% after 3000 cycles at 20 mA/cm2. The high-energy storage performances suggested that the obtained ultrathin and porous NiCo2O4 nanosheet-based 3D hierarchical electrode materials could be a prospective candidate in the field of energy storage.
The Polytropic Approach in Modeling Compressible Flows Through Constant Cross-Section Pipes
Authors: Ferrari Alessandro , Vento Oscar , Zhang Tantan
Published: April 2021

A compressible flow with wall friction has been predicted in a constant cross section duct by means of a barotropic modeling approach, and new analytical formulas have been proposed that also allow any possible heat transfer to the walls to be taken into account. A comparison between the distributions of the steady-state flow properties, pertaining to the new formulas, and those of a classic Fanno analysis has been performed. In order to better understand the limits of the polytropic approach in nearly chocked flow applications, a numerical code, which adopts a variable polytropic coefficient along the duct, has been developed. The steady-state numerical distributions along the pipe, obtained for either a viscous adiabatic or an inviscid diabatic flow by means of this approach, coincide with those of the Fanno and Rayleigh models for Mach numbers up to 1. A constant polytropic exponent can be adopted for a Fanno flow that is far from choking conditions, while it cannot be adopted for the simulation of a Rayleigh flow, even when the flow is not close to choking conditions. Finally, under the assumption of diabatic flows with wall friction, the polytropic approach, with a constant polytropic exponent, is shown to be able to accurately approximate cases in which no local maximum is present for the temperature along the duct. The Mach number value at the location where the local maximum temperature possibly occurs has been obtained by means of a new analytical formula.
Hardened Edges Effects on Wear Characteristics of Cultivator Sweeps Using Circular Soil Bin Test
Authors: Tekeste Mehari Z. , Balvanz Loran R. , Al-Aani Firas , Boesenberg Adam , Hatfield Jerry L.
Published: April 2021

Tillage tools are subject to friction and low-stress abrasive wear processes with the potential deterioration of the desired soil quality, loss of mechanical weed efficacy, and downtime for replacing worn tools. Limited experimental methods exist to quantify investigate the effect of wear-resistant coatings on shape parameters of soil-engaging tools. ASTM standard sand/rubber wheel abrasion and pin-on-disk tests are not able to simulate wear characteristics of the complex shape of the tillage tools. Even though the tribology of tillage tools can be realistic from field tests, tillage wear tests under field conditions are expensive and often challenging to generate repeatable engineering data due to variable soil conditions in the field. A technique that simulated tillage wear of cultivator sweep in a circular soil bin filled with abrasive gravel medium and moisture condition was developed and applied to quantify the wear characteristics of cultivator sweeps with and without hardfaced edges. The hardfaced cultivator sweep had a cemented carbide chip applied to the bottom cutting edge and front tip sections of a standard cultivator sweep according to a proprietary CADEN Edge welding process. The CADEN Edge hardfaced sweeps showed improved wear performance 1.7 times and 3.5 times on mass and shape (sweep length and sweep wing cutting width) dimensions, respectively, compared with the un-hardened standard sweep. The results implied hardfaced cultivator sweep with cemented carbide chips provide potential in maintaining tillage productivity and the desired soil quality for seed-bed preparation.
Genetic Algorithm-Based Optimal Design of a Rolling-Flying Vehicle
Authors: Jenkins Tyler , Atay Stefan , Buckner Gregory , Bryant Matthew
Published: April 2021

This work describes a design optimization framework for a rolling-flying vehicle consisting of a conventional quadrotor configuration with passive wheels. For a baseline comparison, the optimization approach is also applied for a conventional (flight-only) quadrotor. Pareto-optimal vehicles with maximum range and minimum size are created using a hybrid multi-objective genetic algorithm in conjunction with multi-physics system models. A low Reynolds number blade element momentum theory aerodynamic model is used with a brushless DC motor model, a terramechanics model, and a vehicle dynamics model to simulate the vehicle range under any operating angle-of-attack and forward velocity. To understand the tradeoff between vehicle size and operating range, variations in Pareto-optimal designs are presented as functions of vehicle size. A sensitivity analysis is used to better understand the impact of deviating from the optimal vehicle design variables. This work builds on current approaches in quadrotor optimization by leveraging a variety of models and formulations from the literature and demonstrating the implementation of various design constraints. It also improves upon current ad hoc rolling-flying vehicle designs created in previous studies. Results show the importance of accounting for oft-neglected component constraints in the design of high-range quadrotor vehicles. The optimal vehicle mechanical configuration is shown to be independent of operating point, stressing the importance of a well-matched, optimized propulsion system. By emphasizing key constraints that affect the maximum and nominal vehicle operating points, an optimization framework is constructed that can be used for rolling-flying vehicles and conventional multi-rotors.
Aeroacoustic differences between the Japanese fricatives [ɕ] and [ç]
Authors: Yoshinaga Tsukasa , Maekawa Kikuo , Iida Akiyoshi
Published: April 2021

To elucidate the linguistic similarity between the alveolo-palatal sibilant [ɕ] and palatal non-sibilant [ç] in Japanese, the aeroacoustic differences between the two consonants were explored via experimentation with participants and analysis using simplified vocal tract models. The real-time magnetic resonance imaging (rtMRI) observations of articulatory movements demonstrated that some speakers use a nearly identical place of articulation for /si/ [ɕi] and /hi/ [çi]. Simplified vocal tract models were then constructed based on the data captured by static MRI, and the model-generated synthetic sounds were compared with speaker data producing [ɕ] and [ç]. Speaker data demonstrated that the amplitude of the broadband noise of [ç] was weaker than that of [ɕ]; the characteristic peak amplitude at approximately 4 kHz was greater in [ç] than in [ɕ], although the mid-sagittal vocal tract profiles were nearly identical for three of ten subjects in the rtMRI observation. These acoustic differences were reproduced by the proposed models, with differences in the width of the coronal plane constriction and the flow rate. The results suggest the need to include constriction width and flow rate as parameters for articulatory phonetic descriptions of speech sounds.
Analysis of correlation between window duration for kurtosis computation and accuracy of noise-induced hearing loss prediction
Authors: Tian Yu , Ding Wenxi , Zhang Meibian , Zhou Tianshu , Li Jingsong , Qiu Wei
Published: April 2021

Kurtosis is considered an important metric for evaluating noise-induced hearing loss (NIHL). However, how to select window duration to calculate kurtosis remains unsolved. In this study, two algorithms were designed to investigate the correlation between window duration for kurtosis computation and the accuracy of NIHL prediction using a Chinese industrial database. Pure-tone hearing threshold levels (HTLs) and full-shift noise were recorded from each subject. In the statistical comparison, subjects were divided into high- and low-kurtosis groups based on kurtosis values computed over different window durations. Mann–Whitney U test was used to compare the difference in group HTLs to find the optimal window duration to best distinguish these two groups. In the support vector machine NIHL prediction model, kurtosis obtained from different window durations was used as a feature of the model for NIHL evaluation. The area under the curve was used to evaluate the performances of models. Fourteen window durations were tested for each algorithm. Results showed that 60 s was an optimal window duration that allows for both efficient computation and high accuracy for NIHL evaluation at test frequencies of 3, 4 and 6 kHz, and the geometric mean of kurtosis sequence was the best metric in NIHL evaluation.
Shear jamming onset in dense granular suspensions
Authors: Cao Saisai , Wang Yu , Pang Haoming , Zhang Junshuo , Wu Yuxuan , Xuan Shouhu , Gong Xinglong
Published: April 2021

Discontinuous shear thickening and dynamic shear jamming can be observed in the dense granular suspension. Here, we determine the criterion for the occurrence of shear jamming by studying the first normal stress difference N1 of dense granular suspension in steady-state rheology. When N1=0, the suspension is shear jammed, and the frictional contact dominates the framework. The jamming onset stress decreases when the particle volume fraction increases. The lubrication to friction mechanism predicts the occurrence of shear jamming and is consistent with the trend predicted by the Wyart–Cates model. The state of a dense granular suspension can be distinguished in the state diagram via the analysis of N1. This work can aid understanding of the rheology of concentrated particle suspensions.
Effect of Cognitive Loading on Single-Leg Jump Landing Biomechanics of Elite Male Volleyball Players
Authors: Mohammad Amoli Sima , Aghaie Ataabadi Peyman , Letafatkar Amir , Wilkerson Gary B. , Mansouri Misagh B.
Published: April 2021

Anterior cruciate ligament (ACL) injury is prevalent during the single-leg jump landing in various sports. The effects of cognitive loading and how it affects risk of ACL injury are not well understood. The purpose of this study is to examine how landing kinetics change in the presence of cognitive loading during a volleyball block. Cognitive loading decreased activations in vastus lateralis and rectus femoris, and increased activation in biceps femoris and medial gastrocnemius muscles. During landing, the first and second peaks of ground reaction forces were 13% and 11% lower under cognitive loading, suggesting that cognitive loading alters landing biomechanics and muscle activations.
Extraction of organic chemistry grammar from unsupervised learning of chemical reactions
Authors: Schwaller Philippe , Hoover Benjamin , Reymond Jean-Louis , Strobelt Hendrik , Laino Teodoro
Published: April 2021

RXNmapper constructs coherent atom-mapping rules from raw chemical reactions using unsupervised training of neural networks.
A selective HDAC8 inhibitor potentiates antitumor immunity and efficacy of immune checkpoint blockade in hepatocellular carcinoma
Authors: Yang Weiqin , Feng Yu , Zhou Jingying , Cheung Otto Ka-Wing , Cao Jianquan , Wang Jing , Tang Wenshu , Tu Yalin , Xu Liangliang , Wu Feng , Tan Zhiwu , Sun Hanyong , Tian Yuan , Wong John , Lai Paul Bo-San , Chan Stephen Lam , Chan Anthony Wing-Hung , Tan Patrick Boon-Ooi , Chen Zhiwei , Sung Joseph Jao-Yiu , Yip Kevin Yuk-Lap , To Ka-Fai , Cheng Alfred Sze-Lok
Published: April 2021

HDAC8 inhibition elicits durable responses to immune checkpoint blockade by improving adaptive immune responses through enhancer reprogramming.
Ultrasensitive point-of-care immunoassay for secreted glycoprotein detects Ebola infection earlier than PCR
Authors: Fontes Cassio M. , Lipes Barbara D. , Liu Jason , Agans Krystle N. , Yan Aiwei , Shi Patricia , Cruz Daniela F. , Kelly Garrett , Luginbuhl Kelli M. , Joh Daniel Y. , Foster Stephanie L. , Heggestad Jacob , Hucknall Angus , Mikkelsen Maiken H. , Pieper Carl F. , Horstmeyer Roarke W. , Geisbert Thomas W. , Gunn Michael D. , Chilkoti Ashutosh
Published: April 2021

An immunoassay that targets the nonstructural secreted glycoprotein decoy antigen of Ebola virus detects infection earlier than PCR.
SerpinB13 antibodies promote β cell development and resistance to type 1 diabetes
Authors: Kryvalap Yury , Jiang Matthew L. , Kryvalap Nadzeya , Hendrickson Cole , Czyzyk Jan
Published: April 2021

Antibody binding to protease inhibitor serpinB13 promotes proteolytic breakdown of Notch1 and generation of pancreatic endocrine cells.
Genetic Suppression of Lethal Mutations in Fatty Acid Biosynthesis Mediated by a Secondary Lipid Synthase
Authors: Allemann Marco N. , Allen Eric E.
Published: April 2021

A defining trait among many cultured piezophilic and/or psychrophilic marine
Gammaproteobacteria
is the incorporation of both monounsaturated and polyunsaturated fatty acids into membrane phospholipids. The biosynthesis of these different classes of fatty acid molecules is linked to two genetically distinct co-occurring pathways that utilize the same pool of intracellular precursors.
Novel custom made composite spacer for first-stage revision total hip replacement in the presence of extensive acetabular/femoral bone loss with abductor deficiency
Authors: Brown Cameron Douglas , Joseph Jibu John
Published: April 2021

A two-stage revision total hip replacement (THR) remains the gold standard for treating chronic periprosthetic joint infection. The goals for the first stage are twofold: (1) remove infected tissue/implants, obtaining tissue samples for culture; (2) deliver local antibiotics and maintain hip function with a prosthesis with antibiotic-loaded acrylic cement. With extensive bone loss prefabricated spacers are not sufficient, therefore customised spacers are required. The current technique, coating cephalomedually femoral nail in cement, is complex, time consuming, functions poorly and causes wear debris from excessive friction at the femoral/acetabular articulation. We report a technique to create a custom made composite spacer using a short femoral nail, standard Exeter femoral stem (Stryker), Trident acetabular cup (Stryker) and polymethyl methacrylate (PMMA) bone cement with antibiotics. This technique restores hip biomechanics and gives a stable articulation, even in the presence of abductor deficiency, due to dual mobility bearings.
Neurofibroma of the hard palate
Authors: Cartwright Bethany , Corsar Kenneth
Published: April 2021

Neurofibromas are defined as benign tumours arising from peripheral nerve sheaths. Few intraoral palatal cases have been reported. Neurofibromas can occur as part of neurofibromatosis, type 1 (NF1) or type 2 (NF2). A 41-year-old patient presented with a slowly enlarging soft tissue mass on the hard palate. An incisional biopsy was performed, which confirmed the diagnosis of a neurofibroma associated with NF1. It should be considered that there is a chance of malignant transformation. Here, we discuss the clinical features, types, diagnosis, histopathology and treatment options.
Extensive pulmonary artery embolisation caused by cardiac hydatid cyst rupture
Authors: Dind Ashleigh , Harmer Jason A , Hansen Peter S , Harris Benjamin
Published: April 2021

This case study is a rare example of cardiac hydatidosis in a high-income country, where a middle-aged man presented with a ruptured right ventricular cyst causing anaphylaxis, pulmonary emboli and dissemination ofEchinococcusthroughout the lung. He survived the cyst rupture and underwent cardiac surgery but had incomplete resection and experienced progressive cardiopulmonary hydatidosis despite antihelminthic therapy. As a result, he experienced an array of cardiopulmonary sequelae over his lifespan. This case report highlights rare clinical manifestations of hydatid disease and potential complications of its treatment.
Linked electronic health records for research on a nationwide cohort of more than 54 million people in England: data resource
Authors: Wood Angela , Denholm Rachel , Hollings Sam , Cooper Jennifer , Ip Samantha , Walker Venexia , Denaxas Spiros , Akbari Ashley , Banerjee Amitava , Whiteley William , Lai Alvina , Sterne Jonathan , Sudlow Cathie
Published: April 2021

Objective

To describe a novel England-wide electronic health record (EHR) resource enabling whole population research on covid-19 and cardiovascular disease while ensuring data security and privacy and maintaining public trust.

Design

Data resource comprising linked person level records from national healthcare settings for the English population, accessible within NHS Digital’s new trusted research environment.

Setting

EHRs from primary care, hospital episodes, death registry, covid-19 laboratory test results, and community dispensing data, with further enrichment planned from specialist intensive care, cardiovascular, and covid-19 vaccination data.

Participants

54.4 million people alive on 1 January 2020 and registered with an NHS general practitioner in England.

Main outcome measures

Confirmed and suspected covid-19 diagnoses, exemplar cardiovascular conditions (incident stroke or transient ischaemic attack and incident myocardial infarction) and all cause mortality between 1 January and 31 October 2020.

Results

The linked cohort includes more than 96% of the English population. By combining person level data across national healthcare settings, data on age, sex, and ethnicity are complete for around 95% of the population. Among 53.3 million people with no previous diagnosis of stroke or transient ischaemic attack, 98 721 had a first ever incident stroke or transient ischaemic attack between 1 January and 31 October 2020, of which 30% were recorded only in primary care and 4% only in death registry records. Among 53.2 million people with no previous diagnosis of myocardial infarction, 62 966 had an incident myocardial infarction during follow-up, of which 8% were recorded only in primary care and 12% only in death registry records. A total of 959 470 people had a confirmed or suspected covid-19 diagnosis (714 162 in primary care data, 126 349 in hospital admission records, 776 503 in covid-19 laboratory test data, and 50 504 in death registry records). Although 58% of these were recorded in both primary care and covid-19 laboratory test data, 15% and 18%, respectively, were recorded in only one.

Conclusions

This population-wide resource shows the importance of linking person level data across health settings to maximise completeness of key characteristics and to ascertain cardiovascular events and covid-19 diagnoses. Although this resource was initially established to support research on covid-19 and cardiovascular disease to benefit clinical care and public health and to inform healthcare policy, it can broaden further to enable a wide range of research.
Physiotherapist-led treatment for femoroacetabular impingement syndrome (the PhysioFIRST study): a protocol for a participant and assessor-blinded randomised controlled trial
Authors: Kemp Joanne L , Johnston Richard T R , Coburn Sally L , Jones Denise M , Schache Anthony G , Mentiplay Benjamin F , King Matthew G , Scholes Mark J , De Oliveira Silva Danilo , Smith Anne , McPhail Steven M , Crossley Kay M
Published: April 2021

Introduction

This double-blind, randomised controlled trial (RCT) aims to estimate the effect of a physiotherapist-led intervention with targeted strengthening compared with a physiotherapist-led intervention with standardised stretching, on hip-related quality of life (QOL) or perceived improvement at 6 months in people with femoroacetabular impingement (FAI) syndrome. We hypothesise that at 6 months, targeted strengthening physiotherapist-led treatment will be associated with greater improvements in hip-related QOL or greater patient-perceived global improvement when compared with standardised stretching physiotherapist-led treatment.

Methods and analysis

We will recruit 164 participants with FAI syndrome who will be randomised into one of the two intervention groups, both receiving one-on-one treatment with the physiotherapist over 6 months. The targeted strengthening physiotherapist-led treatment group will receive a personalised exercise therapy and education programme. The standardised stretching physiotherapist-led treatment group will receive standardised stretching and personalised education programme. Primary outcomes are change in hip-related QOL using International Hip Outcome Tool-33 and patient-perceived global improvement. Secondary outcomes include cost-effectiveness, muscle strength, range of motion, functional task performance, biomechanics, hip cartilage structure and physical activity levels. Statistical analyses will make comparisons between both treatment groups by intention to treat, with all randomised participants included in analyses, regardless of protocol adherence. Linear mixed models (with baseline value as a covariate and treatment condition as a fixed factor) will be used to evaluate the treatment effect and 95% CI at primary end-point (6 months).

Ethics and dissemination

The study protocol was approved (La Trobe University Human Ethics Committee (HEC17-080)) and prospectively registered with the Australian New Zealand Clinical Trials Registry. The findings of this RCT will be disseminated through peer reviewed scientific journals and conferences. Patients were involved in study development and will receive a short summary following the completion of the RCT.

Trial registration number

ACTRN12617001350314
Study protocol for randomised clinical trial comparing the effectiveness of side-lying sleep positioning to back-lying at reducing oxygen desaturation resulting from obstructive sleep apnoea in infants with cleft palate (SLUMBRS2)
Authors: Metryka Aleksandra , Cunniffe Claire , Evans Hazel J , Gavlak Johanna G , Hudson Nichola , Kirby Nigel , Lakhanpaul Monica , Lin Yin-Ling , Murray Clare , Rajai Azita , Robson Helen , Schilder Anne , Walsh Tanya , Bruce Iain
Published: April 2021

Introduction

The craniofacial abnormalities found in infants with cleft palate (CP) decrease their airway patency and increase their risk of obstructive sleep apnoea (OSA). We hypothesise that optimising sleep position in infants with CP may improve airway patency and offer a ‘low-cost, high-impact’ intervention to prevent the negative impacts of OSA. Because cleft centres give inconsistent advice about sleep position: some recommend back-lying and others side-lying, we will compare these in a randomised controlled trial.

Methods and analysis

The aim is to determine the clinical effectiveness of side-lying as compared with back-lying sleep positioning in terms of reducing oxygen desaturation resulting from OSA in 244 infants aged 3–5 weeks of age, diagnosed with an isolated CP in/by UK cleft centres. Primary outcome is the 4% Oxygen Desaturation Index measured using pulse oximetry during sleep.

Research plan

1. Multicentre randomised controlled trial of side-lying compared with back-lying sleep positioning in reducing oxygen desaturation resulting from OSA in infants with CP at one month of age. 2. Internal pilot questionnaire-based study to support parents and clinicians regarding study participation, seeking to identify and address any barriers to recruitment. Monitoring data from the internal pilot will be used in the final analysis. 3. Co-development of new UK recommendations with Cleft Lip and Palate Association (CLAPA) regarding sleep position for infants with CP.

Ethics and dissemination

The study protocol has received the favourable opinion of the West Midlands-South Birmingham Research Ethics Committee. Study results will be published on affiliated webpages and in peer-reviewed publications and conference contributions.

Trial registration number

NCT04478201.
Radiation dose and fraction in immunotherapy: one-size regimen does not fit all settings, so how does one choose?
Authors: Demaria Sandra , Guha Chandan , Schoenfeld Jonathan , Morris Zachary , Monjazeb Arta , Sikora Andrew , Crittenden Marka , Shiao Stephen , Khleif Samir , Gupta Seema , Formenti Silvia Chiara , Vikram Bhadrasain , Coleman C Norman , Ahmed Mansoor M
Published: April 2021

Recent evidence indicates that ionizing radiation can enhance immune responses to tumors. Advances in radiation delivery techniques allow hypofractionated delivery of conformal radiotherapy. Hypofractionation or other modifications of standard fractionation may improve radiation’s ability to promote immune responses to tumors. Other novel delivery options may also affect immune responses, including T-cell activation and tumor-antigen presentation changes. However, there is limited understanding of the immunological impact of hypofractionated and unique multifractionated radiotherapy regimens, as these observations are relatively recent. Hence, these differences in radiotherapy fractionation result in distinct immune-modulatory effects. Radiation oncologists and immunologists convened a virtual consensus discussion to identify current deficiencies, challenges, pitfalls and critical gaps when combining radiotherapy with immunotherapy and making recommendations to the field and advise National Cancer Institute on new directions and initiatives that will help further development of these two fields.

This commentary aims to raise the awareness of this complexity so that the need to study radiation dose, fractionation, type and volume is understood and valued by the immuno-oncology research community. Divergence of approaches and findings between preclinical studies and clinical trials highlights the need for evaluating the design of future clinical studies with particular emphasis on radiation dose and fractionation, immune biomarkers and selecting appropriate end points for combination radiation/immune modulator trials, recognizing that direct effect on the tumor and potential abscopal effect may well be different. Similarly, preclinical studies should be designed as much as possible to model the intended clinical setting. This article describes a conceptual framework for testing different radiation therapy regimens as separate models of how radiation itself functions as an immunomodulatory ‘drug’ to provide alternatives to the widely adopted ‘one-size-fits-all’ strategy of frequently used 8 Gy×3 regimens immunomodulation.
Practical computer vision application to detect hip fractures on pelvic X-rays: a bi-institutional study
Authors: Choi Jeff , Hui James Z , Spain David , Su Yi-Siang , Cheng Chi-Tung , Liao Chien-Hung
Published: April 2021

Background

Pelvic X-ray (PXR) is a ubiquitous modality to diagnose hip fractures. However, not all healthcare settings employ round-the-clock radiologists and PXR sensitivity for diagnosing hip fracture may vary depending on digital display. We aimed to validate a computer vision algorithm to detect hip fractures across two institutions’ heterogeneous patient populations. We hypothesized a convolutional neural network algorithm can accurately diagnose hip fractures on PXR and a web application can facilitate its bedside adoption.

Methods

The development cohort comprised 4235 PXRs from Chang Gung Memorial Hospital (CGMH). The validation cohort comprised 500 randomly sampled PXRs from CGMH and Stanford’s level I trauma centers. Xception was our convolutional neural network structure. We randomly applied image augmentation methods during training to account for image variations and used gradient-weighted class activation mapping to overlay heatmaps highlighting suspected fracture locations.

Results

Our hip fracture detection algorithm’s area under the receiver operating characteristic curves were 0.98 and 0.97 for CGMH and Stanford’s validation cohorts, respectively. Besides negative predictive value (0.88 Stanford cohort), all performance metrics—sensitivity, specificity, predictive values, accuracy, and F1 score—were above 0.90 for both validation cohorts. Our web application allows users to upload PXR in multiple formats from desktops or mobile phones and displays probability of the image containing a hip fracture with heatmap localization of the suspected fracture location.

Discussion

We refined and validated a high-performing computer vision algorithm to detect hip fractures on PXR. A web application facilitates algorithm use at the bedside, but the benefit of using our algorithm to supplement decision-making is likely institution dependent. Further study is required to confirm clinical validity and assess clinical utility of our algorithm.

Level of evidence

III, Diagnostic tests or criteria.
Comparative study of hexanal dip and electrospun nanofiber mediated vapour treatments on enhancing the shelf life of pears
Authors: Ranjan Syndhiya , Paliyath Gopinadhan , Lim Loong-Tak , Subramanian Jayasankar
Published: April 2021

Hexanal slows down the ripening process in fresh produce by inhibiting the activity of phospholipase D, thereby increasing shelf life. This study focused on comparing the single time exposure and continuous exposure of post-harvest Anjou and Bartlett pears to hexanal by dipping or fumigating them to enhance their shelf life. Continuous exposure of hexanal was achieved by developing a hexanal encapsulated fiber (HEF), which releases hexanal vapor due to the increased humidity (96 ± 2% RH) in the container headspace as a result of respiration. The fruits were stored in cold storage (0 ± 2 °C) as well as at normal room temperature (20 ± 2 °C) and their storage capacity was compared between the treatments. Fruit parameters such as physiological loss of weight (PLW), firmness, and total soluble solids (TSS) showed only minor differences between hexanal treated and untreated fruits. Between the two varieties, Anjou exhibited slightly higher values than Bartlett. However, when the fruits are visually evaluated, the main aspect of consumer preference, HEF-treated fruits had a better appeal in both varieties and in both conditions. Bartlett responded better than Anjou even in cold storage conditions, suggesting that there are varietal differences in their response to hexanal. Both hexanal treatments helped color retention and reduced fungal infection under the storage conditions tested.
Experimental investigations and aerodynamic shape optimization of small horizontal-axis wind turbine blades
Authors: Chaudhary Manoj Kumar , Prakash S.
Published: April 2021

This study aims to optimize and investigate small horizontal-axis wind turbine blades at low wind speeds. The objective of this study is to explain the design method based on BEM theory for 0.2 m blade rotors with constant, variable, and linear chord with twisted blade geometry. MATLAB and Xfoil programs were used to apply BEM principles on wind turbines with SG6043 airfoil. Numerical and experimental studies were carried out to examine the impact of rotor solidity values from 0.057 to 0.207 and the number of blades from 3 to 7. The experimental blades were developed using a 3D printing additive manufacturing technique. The rotors were investigated in an open wind tunnel at wind speeds ranging from 2 to 8 m/s. The initial investigation range included tip speed ratios from 2 to 8 and angles of attacks from 2° to 20°. Subsequently, these parameters were varied in Matlab and Xfoil software to optimization and investigate the power coefficient, blade geometry, number of blades, and blade pitch angle. It was found that a rotor solidity of 0.055–0.085 displayed better performance.