bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying the Pose Between a Head Mounted Display and a Head Pose Sensor
Authors: Reynolds Craig , Everett Louis J. , Volz Richard A.
Published: December 2020

Head mounted displays (HMDs) are common hardware in a virtual reality environment. Sensors are commonly installed on the helmet to provide information about where the operator is looking. If the operator rotates the helmet, the virtual scene should rotate correspondingly. If the point of rotation (POR) of the operator’s head differs from the POR used to transform the image, the display may behave in bizarre ways. In “enhanced reality” and similar applications the virtual scene must also accurately correspond to the real world. When the virtual scene must accurately correspond to a real scene, it becomes necessary to accurately match the virtual display to the real world. A method for automatically collecting data to align these scenes is described and demonstrated in this paper. A theoretical basis for the method and experimental data are presented. Results indicate that the underlying assumptions of the theory are reasonable and that the errors in the method are reasonable.
Dynamic Modeling and Analysis of a Two D.O.F. Mobile Manipulator
Authors: Naderi D. , Meghdari A. , Durali M.
Published: December 2020

This paper presents the kinematic and dynamic modeling of a two degrees of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an irregular ground-surface while the end-effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of highly coupled dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Finally, simulation results for the end-effector’s straight-line trajectory are presented to illustrate these effects.
Unstable Configurations and Redundant Actuation in Planar Mechanisms
Authors: Kohli D. , Pan C. A. , Dhingra A. K.
Published: December 2020

In an unstable configuration, a mechanism loses controllability and gains at least one unwanted degree of freedom (DOF) instantaneously. Based on the concept of direct kinematics singularity, we develop an analytical formulation to express unstable configurations of planar N-link mechanisms with single or multiple loops. The dependence of unstable configurations, on the choice of input links, is illustrated through a 7-link 2-DOF mechanism. The unstable configurations are derived for fifteen input link combinations, which are chosen from two different active inputs in six movable links. To gain mechanism controllability at unstable configurations, actuators at passive joints can be introduced. By changing inputs at the unstable configuration and actively actuating one of the passive joints, we gain controllability. It is shown that for a mechanism with F degrees of freedom and L independent closed-loops, the minimum number of actuators needed to fully control the mechanism is F + L.
FEM Model for the Tooth Root Bending Stress Analysis of Mating Helical Gears
Authors: Ambruosi Giancarlo , Bianco Giuseppe , Corte Orazio Della , Lang Claus-Hermann , Paradiso Domenico , Pierro Gennaro
Published: December 2020

The role of simulation in the engineering phase of the product is becoming increasingly important, due to the variety of analysis which can be performed in a shorter time and at reduced costs also identifying weak spots of a component or system, before volume parts have been produced.

An FEM model of mating cylindrical helical gears has been developed with the aim of evaluating tooth root bending stress during the engagement.

The accurate description of the tooth geometry was provided by an in-house developed software having a direct interface with the FEM pre-processor. This software simulates the manufacturing process, taking into account the geometry of manufacturing tools and the machining parameters. Tooth micro-geometry corrections have been included to better match the real geometry.

In the FEM model, the tooth mesh has been optimized in order to reduce the errors due to the domain discretization, in the numerical solution of the contact problem. A non-congruent mesh with special connectivity has been used to minimize the model size and therefore the computation time.

The model has been validated by experimental data. Static tests have been performed on innovative test apparatus. The test rig allows the measurement of tooth root bending strains of two mating helical gears engaged in a specified fixed mesh position.
Performance Rating and Optimization of Spur Gear Drives With Small Number of Teeth
Authors: Arikan M. A. Sahir
Published: December 2020

Performance rating of spur gear drives with small number of teeth is made and variations of contact ratio, circular tooth thicknesses at pinion and gear tooth tips, lengths of the pinion addendum and dedendum portions of the line of action, AGMA geometry factor J for the pinion and the gear and their ratio, and AGMA geometry factor I with addendum modification coefficient are determined. Thus, it is made possible to design gear drives with properties such as, maximum possible contact ratio, maximum length of the pinion addendum portion of the line of action, maximum length of the pinion dedendum portion of the line of action, equal AGMA geometry factors J for the pinion and the gear (i.e. equal pinion and gear tooth root stresses), and maximum AGMA geometry factor I (i.e. minimum tooth contact stress). Rack cutter tip fillet radius and rack cutter geometry are considered in the analysis, which are the basic factors that determine the gear tooth fillet profile.
A New Approach to Design Multi-Stage Gear Drives Using Simulated Annealing Algorithm
Authors: Chong Tae Hyong , Bae Inho
Published: December 2020

The research on the design of gear drives is mainly focused on dimensional design of single-stage gear drives. Recently, however, the need for designing multi-stage gear drives has been increased with more applications of the gear drives in high speed and small space. The design of multi-stage gear drives is a time-consuming process, because it includes some more complicated problems that are not needed to consider in the design of single-stage gear drives. The design problems include not only dimensional design but also configuration design; we have to determine number of reduction stages, to set gear ratios and to configure gear drive elements. There is no definite rule or principle for these types of design problems. Thus the design practices largely depend on the ‘sense’ and the experiences of the designer (mostly done by trial and error).

We propose a new and generalized design algorithm to support designer at the preliminary design phase of multi-stage gear drives, which integrates dimensional design and configuration design process. The proposed design algorithm consists of four steps. In the first step, the user determines number of reduction stages. In the second step, gear ratios of every stage are determined using random search method, and the ratios are used as the basic input for dimensional design of gears in the next step. The dimensions of gears are determined in the third step using generate and test method. The strength and durability of each gear is guaranteed by the bending strength and pitting resistance rating practices using AGMA rating formulas. In the final step, configuration design is carried out using simulated annealing algorithm; the positions of gears and shafts are determined to minimize the geometrical volume (size) of a gearbox while avoiding interferences between them. These steps are carried out iteratively until a desirable solution is acquired.

In order to validate the availability, the proposed design algorithm is applied to the preliminary design of 4-stage gear drives. The design solution shows considerably good results in both aspects of dimensional and configuration design.
Dynamic Behavior of Atmosphere in a Tooth Space of a Spur Gear During Mesh Process From the Viewpoint of Efficient Lubrication
Authors: Houjoh Haruo , Ohshima Shun-ichi , Miyata Shinji , Takimoto Takayuki , Maenami Kentaro
Published: December 2020

Lubrication of gear tooth is necessary for cooling as well as reducing friction losses. It is, however, difficult for rather high speed gear because both rotation of the gear itself and associated aero motion interferes the lubrication. In Addition lubrication consumes excess energy due to such kind of churning.

To realize efficient lubrication it is worthy to feed lubricant from both ends of tooth in axial direction by the aid of sucking action of tooth spaces just after meshing. This probably make possible that the oil can reach the tooth surface as earlier as possible.

Authors investigated the action of air due to pumping action of a spur gear pair by means of both pressure measurement and the hot wire anemometry at the bottom of tooth space to get fundamental data to asses the feasibility of the proposed way. It has been revealed that the behavior is mostly governed by geometric characteristics around the mesh area rather than operational speed, i.e., temporal response of the pressure and flow velocity is proportional to the speed of gear. It has been also found that pressure variation precedes the flow velocity. Sucking phenomena begins when the backlash space passes through the pitch point whereas the pressure is readily negative due to the mass inertia effect of air getting out of the tooth space.
Evaluation of Pitting Life of Carburized Gears Lubricated by ATF and Traction Oil
Authors: Yamanaka Masashi , Kishi Kazuhiko , Inoue Katsumi , Kato Masana , Masuyama Tomoya , Morikawa Kunihiko , Nagahara Mikio
Published: December 2020

This paper presents the result of fatigue tests carried out with an ATF and two types of traction oil. Since the performance of these oils as working fluid is preferred, the performance as a lubricant is inferior. The pitting life is evaluated by the value of D computed by the surface roughness and EHL film thickness. The high traction coefficient causes the tooth surface temperature rise by frictional heat, and then the oil film thickness and pitting life are decreased. To evaluate the performance of these oils as lubricants, the tooth surface temperature at the pitting tests is measured and the EHL film thickness is calculated with it for computing the value of D precisely. All results of fatigue test with three types of oils are examined together and it is found out that they are evaluated by the value of D only. The experimental formula to estimate the pitting life is obtained. This procedure is useful to design the surface gear strength of the automotive ATs and CVTs.
Fatigue Failure and Strength Evaluation of Traction Drive Rollers
Authors: Kato Masana , Deng Gang , Yamanaka Masashi , Yamamoto Ryoji , Ono Noboru , Inoue Katsumi
Published: December 2020

The surface fatigue failures of the traction drive rollers are different to that of gears and bearings because of the high traction force, skew and small slip ratio. In this research, fatigue tests of traction rollers were performed in different slip ratios and skew angles. The effects of running conditions on the fatigue lives of traction drive rollers are clarified and explained based on the surface crack growth and wear situations. Although a higher slip ratio will make a lower fatigue life, the fatigue strength will increase inversley under the skew conditions, because of the differences in mechanical and tribological condition for surface crack growth and the severe surface wear, which diminishes the surface crack length. For evaluation of the effects of such as slip ratio and skew on the fatigue strength of traction rollers, a new method is put forward in which the relationship between the surface temperature index and fatigue life is used instead of S-N curve.
Estimating the Endurance Limit of 9310, 4340M, and 4360 Steel Gears
Authors: Wern Chien , Zareh Hormoz , Carter Matt , Jones Kelly , Renzelmann Mike
Published: December 2020

Single tooth bending fatigue behavior of three gear alloys, namely carburized 9310, induction hardened 4340M and 4360 alloys were examined. The alloys were fabricated into gears having a module of 2.12 (12 diametral pitch) with 12.7 mm (1/2 inch) face width. As the gear geometry was different from that recommended in SAE Single Tooth Gear Bending Fatigue Test standard (SAE-J1619), a test fixture was designed to accommodate these gears. The fixture has the added feature of conjugate action, not found in the SAE test standard. The gears were slowly bent in the fixture to determine the yield load. Then fatigue loads of 85%, 75%, and 65% of yield load were used to determine the number of cycles to failure. The expected endurance limit for single tooth bending fatigue was determined statistically from the finite portion of the load-cycles to failure curve.
Impact Bending Fatigue Strength of Gear Teeth Case-Hardened by Nitriding and Carburizing
Authors: Maenosono Koji , Ishibashi Akira , Sonoda Keiji
Published: December 2020

Almost all gears used for power transmission of automobiles have been case-hardened by carburizing. Recently, strict demand for reducing running noise and vibration from the power transmission gears requires, in most cases, an additional finishing operation such as grinding and/or honing after carburizing. Nitriding is conducted at a temperature of about 820 K which is lower than the transformation temperature, and thus quenching is not required, resulting in smaller heat treatment deterioration. However, nitrided gears hardly used in practice as for power transmission gears.

In the present investigation, experiments were conducted, using test gears case-hardened by two different methods, carburizing and plasma-nitriding. Test results showed that the fatigue strength of carburized gears was higher than that of nitrided gears in most cases when the test gears were made from the same steel. However, the impact fatigue strengths of nitrided gears made from a high tension steel with additional alloy elements Mo and V were higher than those of carburized gears made from the carbon and alloy steels which have been, used as for gear material. The other high tension steel containing neither Mo nor V could not bring about a sufficiently high fatigue strength in comparison with the conventional carburized gears. It should be noted that the impact fatigue strength of carburized gears made from the high tension steel was higher than the ones made of conventional carburizing steel.
Evaluation of Bending Strength of Carburized Gears Based on a Quantification of Defect Size in the Surface Layer
Authors: Masuyama Tomoya , Kato Masana , Inoue Katsumi , Yamashita Toshihiko
Published: December 2020

The fatigue strength of steel is generally proportional to the hardness up to a certain point. However, the relationship of hardness to fatigue strength is more complicated for the case of high strength material, mainly because the defects in the material sensitively reduce the strength. This paper presents a determination of the defect size in carburized gear teeth and a method of strength evaluation based on this size.

A micro notch is artificially processed at the fillet of carburized gear tooth by means of Focused Ion Beam, and the bending fatigue test is performed. The threshold notch depth αn th, which is the limit not to reduce the fatigue strength, is obtained by the test. The threshold notch depth is used as a measure to determine the size of latent defects in the surface layer. The αn th of the gears of which non-martensitic layer is removed by electro-polishing is shorter than the above one.

The surface layer is observed by using scanning electron microscope and electron probe micro analyzer to clarify the characteristics of latent defects. Many micro cracks besides a long crack in the nonmartensitic layer, Cr oxides and Mn oxides near the surface, and Si segregated in grain boundary are observed. This shows they trigger the initiation of fatigue crack, and therefore, the defect size limits the strength. Consequently, the strength is expressed by an experimental formula of vickers hardness and square root of the projected area of the defect obtained above.
Effect of Setting Errors on Manufactured Surfaces of Spiral Bevel Gear and Pinion
Authors: Shunmugam M. S. , Rao B. Subba
Published: December 2020

Settings for generation of spiral bevel gear and pinion are determined in such a manner that the conjugate action in the gear pair is improved during their meshing. Any error in these settings would result in a deviation from the desired surface. Therefore, it is important to identify the critical settings and exercise greater care in their settings. In the present work, simulation of the generation process is carried out and the surfaces obtained are represented with reference to an idealized surface namely the involute spiraloid, established from first principle. The deviations of the surface resulting from the changes in the setting are also presented conveniently as normal deviations. From these results, the critical setting values are identified and are reported in this paper.
Analysis of Single Flank Test Results Providing Topography Errors of Spiral Bevel Gears
Authors: Jerabek Filip , Szánti Gábor , Torvinen Seppo
Published: December 2020

A method for analyzing single flank test results is proposed. The analysis yields geometrical deviations of spiral bevel gears. It is based on extracting information on the meshing tooth surfaces from the transmission error curve and digital photograph of the contact pattern. A neural network is trained by a batch of computer simulated transmission error curves and respective contact patterns belonging to systematically varied geometrical deviations. Taking advantage of the generalization capability of the neural network, it can be used to yield tooth flank topography errors on the basis of single flank test measuring results. Giving similar results to coordinate measurement, the method extends the capabilities of single flank test significantly. It saves costly coordinate measuring time, which may be especially advantageous in case of large bevel gears. It takes only minor changes for the analysis to be applicable for any types of gears.
Load Distribution in Cylindrical Worm Gears
Authors: Simon Vilmos V.
Published: December 2020

A method for the determination of load sharing between the instantaneously engaged worm threads and gear teeth, for the calculation of load distribution along the teeth and transmission errors in different types of cylindrical worm gears is presented. The method covers both cases — that of the theoretical line and point contact. The bending and shearing deflections of worm thread and gear tooth, the local contact deformations of the mating surfaces, the axial deformations of worm body, gear body bending and torsion, deflections of the supporting shafts, and the manufacturing and alignment errors of worm and gear are included. Based on the real load distribution the tooth contact pressure is calculated, in the case of point contact in two different ways, and the obtained results are compared. Also, the total transmission error, consisting of the kinematical transmission error due to the mismatch of the worm gear drive and of the transmission error caused by the deflections of worm thread and gear teeth, is calculated. The method is implemented by a computer program. By using this program the influence of the type of worm gear drive and of design and manufacturing parameters on load distribution and transmission errors is investigated and discussed.
Steady Power Continuously Variable Speed Traction Drive
Authors: Cretu Ovidiu
Published: December 2020

An original continuously variable speed traction drive (variator) is presented. The device is capable of automatically adjusting the transmission ratio according to the value of torque delivered. The device is able to control and sustain a steady power transmitted. A study of the transmission ratio and of the power transmitted by the device is performed using the “Mathematica 4.0”.

The results of the study show that the device can be designed for a large range of power transmitted, making it suitable to be incorporated into the automobile’s power train. The complex geometric configuration generated by simple geometric shapes offers a great potential for optimization for different applications.
A Study on Jumping Characteristics in Synchronous Belt Drives
Authors: Koyama Tomio , Zhang Weiming , Kagotani Masanori
Published: December 2020

The jumping characteristics at the driven pulley of synchronous belt drives are experimentally discussed. The jumping of synchronous belt occurs when the elongation of free span of the belt is over than a certain value. In this paper, an empirical formula for the jumping torque of L type synchronous belt is presented. The following parameters are considered in the empirical formula: tensile stiffness of belt, height of belt tooth, coefficient of traction, belt installation tension, wrapping angle of belt, diameter of pulley pitch circle, bending stiffness of shaft.
Transmission Error Analysis of Helical Gears for Any Load Condition: Practical Calculation Program for Windows PC and Application
Authors: Saiki Kouhei , Watanabe Takeshi
Published: December 2020

Recently, the gear noise reduction of car transmission, especially for light load condition, is of increasing importance due to the unsparing needs of silence. Since the transmission error is the exciting source of gear noise, the purpose of this study, is to establish an effective method to analyze the transmission error of helical gears with any 3-D tooth surface cutting error for any load condition including light load. The shaft misalignment due to the assembly errors, and the variable shaft deflection caused by the transmitted torque, are also considered.

This paper introduces an exact transmission error analysis method of helical gears, in consideration of the nonlinear tooth separation phenomenon at light load condition. As a result, a practical program for Windows personal computer to calculate the transmission error, is also developed. By using this program, the gear designer can find the optimum shape of tooth surface, and the gear producer can evaluate the quality of his manufactured gears.

For confirming the proposed analysis method and the calculation program, the tooth contact pattern of several gear pairs are measured and compared with the calculated result. Especially, it is clarified that the transmission performance of the helicoid bias-in tooth surface modification is better than that of the helicoid bias-out tooth surface modification.
Development of an Analytical Model for the Static and Dynamic Transmission Error Calculation: Validation on a Single Vehicle Gear Vibration Test Bench
Authors: Cricenti Fabrizio , Lang Claus-Hermann , Paradiso Domenico
Published: December 2020

Automotive companies are being challenged when they seek to guarantee very high quality and reliability levels for their products. Customers may complain about comfort and various other concerns such as noise generated by a certain component. Analytical, numerical simulation and testing are used to understand how certain modifications to the product can affect the excited noise level.

This paper presents an analytical approach used in order to predict noise levels coming from an engaged vehicle gear pair. This is done by evaluating the static and dynamic transmission error with load distribution on the teeth engaged for the different values of micro-geometric teeth modifications. Comparing the analytical and experimental results shows that both factors can be extremely linked with noise generated by two mating gears.
Study of Transient Response of a Gear Train Under Pulsating Torque
Authors: Zhang Q. John , Rescigno Jerry
Published: December 2020

This paper studied the transient response of a single reduction gear train under a pulsating torque. A 4-DOF model has been used to estimate the impact load on the gear teeth. The system equations are solved under different gear backlash, inertia, stiffness and gear ratio conditions. The sensitivities of impact load versus these parameters have been summarized. The nonlinear behavior of the impact force changing from period to random due to the torque drop is investigated. Angular velocity test verified the power input curve. Angular acceleration and lock-rotor tests show the agreement between the model simulation and experimental result.
The Effect of Gating and Material on Measured Transmission Error and Noise of Injection Molded Gears
Authors: Snow Chris , Houser Donald R. , Luscher Anthony F.
Published: December 2020

The use of plastic gears is expanding in many different markets. Their application is cost-effective when produced on a large scale using a net-shape process such as injection molding. However, variables in the molding process have a direct impact on final gear geometry. In this paper gears molded out of three different polymeric materials using three different gating configurations are used to show the effect of gating on runout, transmission error, and noise. The runout characteristics directly affect long-term transmission error and act to create side banding about the mesh harmonics in the frequency spectrum in both transmission error and noise signals. Additionally, load and speed effects on the gear noise are verified, and gear noise levels for different materials are compared.
Design and Testing of a Compliant Floating-Opposing-Arm (FOA) Centrifugal Clutch
Authors: Crane Nathan B. , Howell Larry L. , Weight Brent L.
Published: December 2020

A floating-opposing-arm (FOA) centrifugal clutch is presented that uses compliant segments to reduce the part count and increase manufacturability. The clutch performs all of the functions of a centrifugal clutch, but consists of only two pieces. Torque is increased by connecting aggressive and non-aggressive contact surfaces in connected pairs. This arrangement increases the torque output of the FOA clutch by over 100% relative to a commercial one-piece compliant centrifugal clutch design of the same size and material. Yet, since this design is compliant, it remains simple to manufacture. This clutch is presented and modeled using the pseudo-rigid-body-model (PRBM) technique. The model predictions are compared to test data from five prototypes. The FOA clutch is also demonstrated in a gasoline-powered string trimmer.
Shakedown Analysis of a Finite Plate With Single Edge Notch Under Uniaxial Tension
Authors: Attia M. S. , Abdel-Karim M. , Megahed M. M.
Published: December 2020

In this paper, the shakedown load factor for a finite rectangular plate with a single edge notch at its mid-length is evaluated by a number of numerical and analytical techniques. These techniques include full elasto-plastic finite element solution coupled with line search technique and an iterative elastic technique known as the elastic compensation method which relies on successive reduction of elastic modulus in regions where elastic stresses exceed yield strength. In addition, an analytical technique proposed recently in the literature, which relies on a gradient optimization technique is employed. The shakedown load factor values obtained through different solution techniques are compared. The comparison showed discrepancies between literature solutions and the solutions presented herein. The reasons behind this discrepancy are scrutinized and certain recommendations are made to ensure validity of shakedown solutions.
Enhanced IL-36R signaling promotes barrier impairment and inflammation in skin and intestine
Authors: Hovhannisyan Zaruhi , Liu Nengyin , Khalil-Aguero Sara , Panea Casandra , VanValkenburgh Jeffrey , Zhang Ruoyu , Lim Wei Keat , Bai Yu , Fury Wen , Huang Tammy , Garnova Elena , Fairhurst Jeanette , Kim Jee , Aryal Smita , Ajithdoss Dharani , Oyejide Adelekan , del Pilar Molina-Portela Maria , E Hock , Poueymirou William , Oristian Nicole Stokes , Brydges Susannah , Liu Xia , Olson William , Yancopoulos George , Murphy Andrew J. , Sleeman Matthew A. , Haxhinasto Sokol
Published: December 2020

Unrestrained IL-36R signaling in a humanized mouse model causes barrier impairment and increased cutaneous and intestinal inflammation.
Tetrahydrophthalazinone Inhibitor of Phosphodiesterase with
In Vitro
Activity against Intracellular Trypanosomatids
Authors: de Araújo Julianna Siciliano , Peres Raiza Brandão , Bernardino da Silva Patrícia , Batista Marcos Meuser , Sterk Geert Jan , Maes Louis , Caljon Guy , Leurs Rob , de Koning Harry P. , Kalejaiye Titilola D. , Soeiro Maria de Nazaré Correia
Published: December 2020

The phosphodiesterase inhibitor tetrahydrophthalazinone NPD-008 was explored by phenotypic
in vitro
screening, target validation, and ultrastructural approaches against
Trypanosoma cruzi
. NPD-008 displayed activity against different forms and strains of
T. cruzi
(50% effective concentration [EC
50
], 6.6 to 39.5 μM). Increased cAMP levels of
T. cruzi
and its combination with benznidazole gave synergistic interaction.
Polysaccharide Copolymerase WzzB/WzzE Chimeras Reveal that the Transmembrane 2 Region of WzzB Is Important for Interaction with WzyB
Authors: Leo Vincenzo , Tran Elizabeth , Morona Renato
Published: December 2020

Bacteria synthesize complex polysaccharide chains at a controlled number of repeating units; this has wide implications for a range of bacterial activities involved in virulence. Examples of complex polysaccharide chains include the Oag component of lipopolysaccharide and the ECA; both of these examples are predominantly synthesized by their own independent Wzy-dependent pathway.
Combining 3D-Printed Models and Open Source Molecular Modeling of p53 To Engage Students with Concepts in Cell Biology
Authors: Segarra Verónica A. , Chi Richard J.
Published: December 2020

While understanding macromolecular structural elements and their roles in dictating cellular function is critical to grasp basic concepts in biology, it can be challenging for students to master this content—these elements naturally exist at the nanoscale and are not observable with the naked eye. Oftentimes this understanding is catalyzed by impactful illustrations and animations found online and in textbooks. In recent years, 3D printing technology has become readily accessible as an additional way to generate models and visualize entities of interest. In this report, we describe and discuss the efficacy of an approach using 3D-printed models in combination with online open-source molecular modeling analyses of the macromolecular structure of p53 to engage students with molecular concepts in cancer cell biology and human health. This pedagogy strategy has been successfully integrated into an upper-level undergraduate course at a primarily undergraduate institution and a graduate biology course at a public research university. We describe the potential benefits while providing tools for others to integrate this strategy into their teaching.
Single-Cell Transcriptomics Reveals a Heterogeneous Cellular Response to BK Virus Infection
Authors: An Ping , Cantalupo Paul G. , Zheng Wenshan , Sáenz-Robles Maria Teresa , Duray Alexis M. , Weitz David , Pipas James M.
Published: December 2020

The outcome of viral infection is determined by the ability of the virus to redirect cellular systems toward progeny production countered by the ability of the cell to block these viral actions. Thus, an infected culture consists of thousands of cells, each fighting its own individual battle.
Effects of multisession transcranial direct current stimulation as an augmentation to cognitive tasks in patients with neurocognitive disorders in Japan: a study protocol for a randomised controlled trial
Authors: Inagawa Takuma , Yokoi Yuma , Yamada Yuji , Miyagawa Nozomi , Otsuka Takeshi , Yasuma Naonori , Omachi Yoshie , Tsukamoto Tadashi , Takano Harumasa , Sakata Masuhiro , Maruo Kazushi , Matsui Mie , Nakagome Kazuyuki
Published: December 2020

Introduction

Transcranial direct current stimulation (tDCS) is a potentially novel strategy for cognitive enhancement in patients with disorders. We present a study protocol for a randomised controlled trial designed to evaluate the safety and efficacy of tDCS combined with cognitive tasks on cognition in such patients.

Method and analysis

This is a two-arm, parallel-design, randomised, sham-controlled trial, in which participants and raters will be blinded at a single centre. Stratified randomisation will be conducted, and a randomisation sequence will be generated through the Electronic Data Capture system. Patients who met the Diagnostic and Statistical Manual of Mental Disorders-5 criteria for neurocognitive disorders will be recruited and randomised to receive either active (2 mA for 20 min) or sham (stimulation ramped up and down for 1 min) stimulation in 10 sessions over five consecutive days. A direct current will be transferred by a 35 cm2 saline-soaked sponge electrode. An anode will be placed over the left dorsolateral prefrontal cortex, and a cathode will be placed over the right supraorbital cortex. Calculation tasks will be conducted in both arms as a cognitive task for 20 min during the stimulation. This task consists of basic arithmetic questions, such as single-digit addition, subtraction, multiplication and division. The primary outcome will be the mean change in the Alzheimer Disease Assessment Scale–cognition at Day 5 after baseline. Depressive symptoms, as measured by the geriatric depression scale, and quality of life, as measured by the Medical Outcomes Study 36-item Short-Form Health Survey, will also be assessed. Data will be collected at baseline, within 3 days following the final stimulation and 1 month thereafter. The estimated sample size is 46 per group based on the assumptions that an estimated mean difference is −1.61 and SD is 2.7. Mixed models for repeated measures will be used for the statistical analysis.

Ethics and dissemination

The National Center of Neurology and the Psychiatry Clinical Research Review Board (CRB3180006) approved this study. The results of this study will be published in a scientific peer-reviewed journal.

Trial registration details

Japan Registry of Clinical Trials jRCTs032180016.
Role of contextual and compositional characteristics of schools for health inequalities in childhood and adolescence: protocol for a scoping review
Authors: Herke Max , Moor Irene , Winter Kristina , Hoffmann Stephanie , Spallek Jacob , Hilger-Kolb Jennifer , Pischke Claudia , Dragano Nico , Novelli Anna , Richter Matthias
Published: December 2020

Introduction

Childhood and adolescence are crucial life stages for health trajectories and the development of health inequalities in later life. The relevance of schools for health and well-being of children and adolescents has long been recognised, and there is some research regarding the association of contextual and compositional characteristics of schools and classes with health, health behaviour and well-being in this population. Little is known about the role of meso-level characteristics in relation to health inequalities. The aim of this scoping review is to retrieve and synthesise evidence about the mediating or moderating role of compositional or contextual characteristics of schools for the association between students’ socioeconomic position and health in primary and secondary education.

Methods and analysis

We will conduct a systematic search of electronic databases in PubMed/Medline, Web of Science and Education Resources Information Center. Studies must meet the following inclusion criteria: (1) The population must be students attending primary or secondary schools in developed economies. (2) The outcomes must include at least one indicator for individual health, health behaviour or well-being. (3) The study must include at least one contextual or compositional characteristic of the school context and one individual determinant of socioeconomic position. (4) The study must also examine the mediating or moderating role of the contextual or compositional characteristic of the school context for the associations between socioeconomic position and health, health behaviour or well-being. (5) The study must be published since 1 January 2000 in English or German language. We will provide a narrative synthesis of findings.

Ethics and dissemination

We will not collect primary data and only include secondary data derived from previously published studies. Therefore, ethical approval is not required. We intend to publish our findings in an international peer-reviewed journal and to present them at national and international conferences.
Whole exome HBV DNA integration is independent of the intrahepatic HBV reservoir in HBeAg-negative chronic hepatitis B
Authors: Svicher Valentina , Salpini Romina , Piermatteo Lorenzo , Carioti Luca , Battisti Arianna , Colagrossi Luna , Scutari Rossana , Surdo Matteo , Cacciafesta Valeria , Nuccitelli Andrea , Hansi Navjyot , Ceccherini Silberstein Francesca , Perno Carlo Federico , Gill Upkar S , Kennedy Patrick T F
Published: December 2020

Objective

The involvement of HBV DNA integration in promoting hepatocarcinogenesis and the extent to which the intrahepatic HBV reservoir modulates liver disease progression remains poorly understood. We examined the intrahepatic HBV reservoir, the occurrence of HBV DNA integration and its impact on the hepatocyte transcriptome in hepatitis B ‘e’ antigen (HBeAg)-negative chronic hepatitis B (CHB).

Design

Liver tissue from 84 HBeAg-negative patients with CHB with low (n=12), moderate (n=25) and high (n=47) serum HBV DNA was analysed. Covalently closed circular DNA (cccDNA), pregenomic RNA (pgRNA) were evaluated by quantitative PCR, whole exome and transcriptome sequencing was performed by Illumina, and the burden of HBV DNA integrations was evaluated by digital droplet PCR.

Results

Patients with low and moderate serum HBV DNA displayed comparable intrahepatic cccDNA and pgRNA, significantly lower than in patients with high HBV DNA, while hepatitis B core-related antigen correlated strongly with the intrahepatic HBV reservoir, reflecting cccDNA quantity. Whole exome integration was detected in a significant number of patients (55.6%, 14.3% and 25% in high, moderate and low viraemic patients, respectively), at a frequency ranging from 0.5 to 157 integrations/1000 hepatocytes. Hepatitis B surface antigen >5000 IU/mL predicted integration within the exome and these integrations localised in genes involved in hepatocarcinogenesis, regulation of lipid/drug metabolism and antiviral/inflammatory responses. Transcript levels of specific genes, including the proto-oncogene hRAS, were higher in patients with HBV DNA integration, supporting an underlying oncogenic risk in patients with low-level to moderate-level viraemia.

Conclusions

HBV DNA integration occurs across all HBeAg-negative patients with CHB, including those with a limited HBV reservoir; localising in genes involved in carcinogenesis and altering the hepatocyte transcriptome.
Frequent police stops, parental incarceration and mental health: results among US non-Hispanic Black and White adolescent girls and boys
Authors: Jahn Jaquelyn L , Agenor Madina , Chen Jarvis T , Krieger Nancy
Published: December 2020

Background

National monitoring of police–public contact does not extend below age 16 and few studies have examined associations with adolescent mental health.

Methods

We describe the distribution of police stops in a nationally representative cross-sectional sample of adolescents ages 12 to 18 years in the Panel Study of Income Dynamics Child Development Supplement 2002 and 2007 (n=2557). We used survey-weighted race/ethnicity-stratified and gender-stratified regression models to examine associations between the frequency of police stops and both depressive symptoms and subjective well-being (emotional, psychological and social). We adjusted for several socioeconomic covariates and evaluated effect modification by parental incarceration.

Results

We estimated that 9.58% of adolescents were stopped two or more times. Despite fewer police stops compared with boys, Black and White girls who were stopped at least two times in the last 6 months had higher average depression scores relative to girls who were not stopped (Black: 2.13 (95% CI: 0.73 to 3.53), White: 2.17 (95% CI: 1.07 to 3.27)) and these associations were stronger among girls whose parents had been incarcerated. Police stops were significantly associated with higher depressive scores for White, but not Black, boys (2+ vs 0 stops: White: 1.33 (95% CI: 0.31 to 2.36, Black: 0.53 (95% CI: –0.28 to 1.34)). Associations between subjective well-being and police stops were stronger among non-Hispanic Black relative to White girls, whereas for boys, associations varied across subjective well-being subscales.

Conclusion

National monitoring data and public health research should examine adolescent police contact at younger ages stratified by both race/ethnicity and gender in order to better understand its relationship with adolescent mental health.
Use of White Cell Count, Age, and Presence of Other Injuries in Stratifying Risk of Intracranial Injury in Pediatric Trauma
Authors: Peyton Margo A , Kouo Theodore , Scott Jennifer , Yanek Lisa R , Ngo Thuy L
Published: December 2020

The Pediatric Emergency Care Applied Research Network (PECARN) Head Injury/Trauma Algorithm is a well-validated decision rule used to identify patients at low risk of clinically important traumatic brain injuries who may not need head CT. In adult patients with mild head trauma, elevated serum glucose and white cell count (WCC) have been associated with abnormal head CT findings. Currently, glucose or WCC is not considered in pediatric patients. The objective of this study was to determine if elevations in glucose or WCC could be used as additional tools to risk-stratify pediatric trauma patients for intracranial injury (ICI). Data were abstracted from the Maryland Trauma Registry and from electronic medical records for patients at the Johns Hopkins Children's Center from 2017 to 2020. We evaluated 145 encounters that met the inclusion criteria. There were 33 cases of ICI on CT. In addition to higher median glucose and WCC, we found that patients with ICI had a younger median age and were less likely to have other clinically significant injuries than patients without ICI. Following multiple logistic regression analysis, WCC (OR 1.113, 95% CI 1.02 to 1.21), younger age (OR 0.89, 95% CI 0.8 to 0.98), and absence of other injuries (OR 0.41, 95% CI 0.23 to 0.73) were found to be associated with risk of ICI. The area under the curve for our model was 0.79. When used with the PECARN algorithm, our model could help determine which patients may avoid head CT or undergo a shorter observation period.
Using a biomarker acutely to identify babies at risk of serious adverse effects from antibiotics: where is the ‘Terrible Moral and Medical Dilemma’?
Authors: Lucassen Anneke M , McDermott John Henry , Newman William
Published: December 2020

We thank Parker and Wright for engaging in this roundtable debate in such a spirited way. The ‘Pharmacogenetic [test] to Avoid Loss of Hearing’ (PALOH) Trial is the first time a genetic point of care test has been applied in the acute neonatal setting; therefore, it is not surprising that questions have been raised which require debate, discussion and clarification. Parker and Wright misattribute several assumptions to the roundtable authors, which we would like to clarify here. Since they raise wider questions about the PALOH trial itself, several of the roundtable discussants have made a joint response.
HPV16 and HPV18 seropositivity and DNA detection among men who have sex with men: a cross-sectional study conducted in a sexual health clinic in London
Authors: King Eleanor M , Mesher David , Sonnenberg Pam , Linley Ezra , Panwar Kavita , Beddows Simon , Soldan Kate , Borrow Ray , Jit Mark , Gilson Richard
Published: December 2020

Objectives

Men who have sex with men (MSM) have an increased risk of human papillomavirus (HPV) infection and related diseases compared with men who have sex exclusively with women. From April 2018, there has been a phased roll-out of HPV vaccination offered to MSM aged up to 45 years old who are attending sexual health clinics and HIV clinics in England. The vaccine is most effective if delivered prior to HPV infection. We estimated the proportion of MSM with no current vaccine-type infection and no serological evidence of prior infection, in a study undertaken prior to vaccine introduction.

Methods

We conducted a cross-sectional study among 484 MSM aged 18–40 years old who attended a sexual health clinic in London between 2010 and 2012. We estimated the prevalence of current and past infection by testing for HPV DNA in anogenital samples and for serum antibodies to HPV16 and HPV18.

Results

The median age was 30 years (IQR 25–35). The prevalence of HPV16 and HPV18 DNA was 13.2% and 6.2%, respectively. Seropositivity for HPV16 and HPV18 was 28.5% and 17.1%, respectively, with 11.4% seropositive for both types. Seropositivity for the same HPV type was strongly associated with anogenital DNA detection. 279 MSM (57.6%) tested negative for both HPV16 and HPV18 serology and were DNA negative for these two types; only 5 MSM (1.0%) were seropositive and DNA positive for both HPV types.

Conclusions

This is the first study to determine both the prevalence of HPV DNA in anogenital samples and HPV seroprevalence among MSM attending a sexual health clinic in the UK. Over half of MSM in this study had no evidence of a previous or current infection with either of the high-risk HPV types included in the quadrivalent vaccine, which supports the rationale for opportunistic HPV vaccination of MSM attending sexual health clinics.
Whole genome sequencing of 10K patients with acute ischaemic stroke or transient ischaemic attack: design, methods and baseline patient characteristics
Authors: Cheng Si , Xu Zhe , Liu Yang , Lin Jinxi , Jiang Yong , Wang Yilong , Meng Xia , Wang Anxin , Huang Xinying , Wang Zhimin , Chen Guohua , Wu Songdi , Jia Zhengchang , Chen Yongming , Qiu Xuerong , Wu Jun , Song Binbin , Ji Weizhong , An Zhongping , Xue Wenjun , Zhao Lili , Geng Yu , Li Hongyan , Li Hao , Wang Yongjun
Published: December 2020

Background and purpose

Stroke is the second leading cause of death worldwide and the leading cause of mortality and long-term disability in China, but its underlying risk genes and pathways are far from being comprehensively understood. We here describe the design and methods of whole genome sequencing (WGS) for 10 914 patients with acute ischaemic stroke or transient ischaemic attack from the Third China National Stroke Registry (CNSR-III).

Methods

Baseline clinical characteristics of the included patients in this study were reported. DNA was extracted from white blood cells of participants. Libraries are constructed using qualified DNA, and WGS is conducted on BGISEQ-500 platform. The average depth is intended to be greater than 30× for each subject. Afterwards, Sentieon software is applied to process the sequencing data under the Genome Analysis Toolkit best practice guidance to call genotypes of single nucleotide variants (SNVs) and insertion-deletions. For each included subject, 21 fingerprint SNVs are genotyped by MassARRAY assays to verify that DNA sample and sequencing data originate from the same individual. The copy number variations and structural variations are also called for each patient. All of the genetic variants are annotated and predicted by bioinformatics software or by reviewing public databases.

Results

The average age of the included 10 914 patients was 62.2±11.3 years, and 31.4% patients were women. Most of the baseline clinical characteristics of the 10 914 and the excluded patients were balanced.

Conclusions

The WGS data together with abundant clinical and imaging data of CNSR-III could provide opportunity to elucidate the molecular mechanisms and discover novel therapeutic targets for stroke.