bluuebunny/crossref_metadata_2025 huggingface dataset:
A Synthesis Method for Placing Workpieces in RPR Planar Robotic Workcells in Which Large Rotations Are Required at the Workpiece
Authors: Chaney K. D. , Davidson J. K.
Published: February 2021

A new method is developed for determining both a satisfactory location of a workpiece and a suitable mounting-angle of the tool for planar RPR robots that can provide dexterous workspace. The method is an analytical representation of the geometry of the robot and the task, and is particularly well suited to applications in which the task requires large rotations of the end-effector. It is determined that, when the task requires that the end-effector rotate a full turn at just two locations and when the first or third joint in the robot is rotatable by one turn, then the radial location of the workpiece is fixed in the workcell but its angular location is not fixed. When the mounting-angle of the tool is also a variable, the method accommodates tasks in which the tool must rotate a full turn at three locations on the workpiece. The results are presented as coordinates of points in a two-dimensional Cartesian reference frame attached to the workcell. Consequently, a technician or an engineer can determine the location for the workpiece by laying out these coordinates directly in the workcell. Example problems illustrate the method. Practical applications include welding and deposition of adhesives.
Assembly Configurations and Branches of Planar Single-Input Dyadic Mechanisms
Authors: Foster David E. , Cipra Raymond J.
Published: February 2021

This paper examines the problem of enumerating the assembly configurations (ACs), also called circuits, of planar single-input dyadic (SID) mechanisms which have links with pin joints and sliding joints. An SID mechanism is a multi-loop mechanism which can be defined by adding one loop at a time such that the mechanism has one degree of freedom after each loop is added. A method is given to find the ACs of such a mechanism. The emphasis is on using graphical interpretation to determine the mobility regions of the mechanism which are preserved when each new loop is added to the mechanism. This method of interpretation is readily automated. Each AC can be represented as a set of instructions for the input link to follow, along with a list of dyad configurations for each instruction. Each instruction corresponds to a branch of the mechanism. Examples are given to demonstrate the use of this method.
Assembly Configurations of Single-Loop Mechanisms With Pin Joints and Sliding Joints
Authors: Foster David E. , Cipra Raymond J.
Published: February 2021

This paper examines the problem of enumerating the assembly configurations (ACs), also called circuits, of planar mechanisms which can be described as a single loop. An algorithm is given which allows the user to find and distinguish the ACs of such a mechanism, by determining if each pair of adjacent links can line up. If each pair can line up, then the mechanism has one AC; otherwise, it has two ACs. It is shown that a single-loop mechanism can have no more than 2 ACs. The algorithm is demonstrated with two examples.
On Force and Motion Control of Serial-Parallel Robots
Authors: Wang Shih-Liang
Published: February 2021

A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.
Design of Tactile Fixtures for Robotics and Manufacturing
Authors: Nederbragt Walter W. , Ravani Bahram
Published: February 2021

This paper presents a theoretical framework for the design of tactile sensing fixtures for robotics and manufacturing. The framework presented uses group theory to analyze the symmetry of contact conditions on a fixture to determine if a fixture design is appropriate to determine the relative location of the sensor frame with respect to the fixture frame. Mechanical fixtures consisting of planar, spherical, and cylindrical surfaces are studied for their usefulness as part of referencing fixtures. The theory developed is used in guiding the design of a simple yet novel touch sensing fixture for part referencing and calibration in manufacturing and robotics.
Velocity Analysis of Truss-Type Manipulators
Authors: Canfield Stephen L. , Soper R. Randall , Hendricks Scott L. , Reinholtz Charles F.
Published: February 2021

A generalized method for the velocity analysis of truss-type manipulators is presented. This analysis relies on a priori knowledge of the position analysis for the manipulator. The approach uses a connectivity chart to define the equations required to determine the velocities of the nodal points of the truss. The problem of determining the nodal velocities is formulated as a linear algebraic relationship for ease of analytical and numerical manipulation. Once each nodal velocity is known, a general description of the overall manipulator velocity is formed by determining the instantaneous screw axis for the output plane. An analytical method for characterizing this output velocity in terms of the instantaneous screw axis is presented.

Analysis of each of the four basic variable geometry truss modules (tetrahedron, octahedron, decahedron, and dodecahedron) is presented. Although ad hoc velocity analyses of many of these manipulators have been presented in the past, the technique presented in this paper is unified for any truss-type manipulator.
Steering Algorithms for an Actively Configurable Wheeled Vehicle
Authors: Waldron Kenneth J.
Published: February 2021

This article describes strategies and algorithms used to steer an unconventionally configured vehicle with twelve continuously controllable degrees of freedom. The WAAV vehicle is a laboratory scale prototype of a vehicle configuration first conceived and studied in simulation as a Mars roving vehicle. It’s configuration is quite different from an automotive vehicle and requires different approaches to directional control. The work described here is restricted to smooth, level terrain, but will be generalized for use on arbitrary, rough terrain.
Extension of Euler’s Principal Axes to Articulated Inertia
Authors: Lipkin Harvey
Published: February 2021

An effective inertia of a serially jointed chain of bodies, such as a robotic arm, is often referred to as the articulated or operational space inertia. Six principal axes and six principal values of inertia are proposed to decouple articulated inertia into geometric and constitutive properties respectively. In the case of a single rigid body, these concepts naturally coincide with familiar descriptions of inertia.
Trajectory Pattern Method Based Trajectory Synthesis and Inverse Dynamics Formulation for Minimal Vibrational Excitation for Flexible Structures
Authors: Tu Q. , Rastegar J.
Published: February 2021

A new approach to trajectory synthesis and formulation of the inverse dynamics model of flexible structures for point to point motions with minimal high frequency component of the actuating torques (forces) is presented. Trajectories are synthesized such that the flexible structure comes to rest undeformed at the completion of motion. The developed method is based on the Trajectory Pattern Method. In this approach, an appropriate trajectory pattern is selected and described in parametric form. The inverse dynamics model of the system is formulated in terms of the trajectory parameters. The trajectory patterns used are in terms of a number of basic sinusoidal time functions and their harmonics. The basic frequencies are selected such that the harmonics appearing in the actuating torques do not excite the natural modes of vibration of the system. For each motion, the trajectory parameters are determined for minimal amplitudes of the higher actuating torque harmonics, noting that from the vibration and control points of view, such trajectories are more desirable. The higher harmonics refers to the harmonics of the actuating torques with frequencies above the highest trajectory harmonic frequency. As an example, a flexible beam undergoing large displacements and rotations in a plane is considered. The effectiveness of the approach is illustrated by an example.
Active Control of Elastodynamic Vibrations of a Four-Bar Mechanism System With a Smart Coupler Link Using Optimal Multivariable Control: Experimental Implementation
Authors: Sannah Muhammad , Smaili Ahmad
Published: February 2021

This paper presents an experimental investigation on active control of the elastodynamic response of a four-bar (4R) mechanism system using “smart” materials featuring piezoelectric sensor/actuator (S/A) pairs and muitivariable optimal control. The experimental (4R) mechanism is made such that its coupler link is flexible, its follower link is slightly less flexible and its crank is relatively rigid. Two thin plate-type piezoceramic S/A pairs are bonded to the flanks of the coupler link at the high strain locations corresponding to the first and second vibration modes. Based on the optimal multivariable control theory, a controller which consists of a linear quadratic regulator (LQR) and a Luenberger observer as a state estimator is designed and implemented.

The results of the experimental investigation prove that in order to prevent high mode excitations, the controller design should be based on the modes representing vibrations of all components comprising the mechanism system rather than the modes corresponding to the link to which the S/A pairs are bonded. Response amplitude attenuation ratios up to 50 percent are achieved and high mode excitations are prevented.
Critical Speed Analysis of Multi-Cylider Engines As Spatial Elastic Linkage Systems
Authors: Kurnool Sirihari , Bagei Cemil
Published: February 2021

A multi-cylinder engine is a cluster of slider-crank linkages. Presently used conventional pure torsional shaft models predict results far from the results predicted considering actual three-dimensional linkage and crankshaft geometries. Pure torsional model doesn’t sense the variation in frequency with the variation in engine geometry. It predicts one constant frequency value for each mode; it does not permit the use of flexible bearings. Article offers a finite element method for performing frequency and critical speed analysis of multi-cylinder engines considering three-dimensional geometries of the linkage loops, crankshaft, and the crankshaft throws, as a spatial elastic mechanism system. Any number of cylinders in any angular orientations with respect to each other may be considered. A three-dimensional flexural finite-line element with isoparametric joint freedom irregularity is developed and used to formulate the eigenvalue equations of motion for the system. Consistent mass matrix as well as lumped mass matrix methods can be used. The element can be restrained to perform coupled torsional and flexural or pure torsional frequency analysis of geared rotor model of engines and shafts on many rigid or flexible bearings. Geared connections can also be considered flexible. A generalized computer program is made available for industrial use. It determines frequencies, mode shapes and critical speed bands of an engine for complete crankshaft rotation for as many modes as desired. The frequency and critical speed analysis of a four-cylinder MGB automobile engine with in-plane crank throws, with and without bearing flexibilities, is performed and the results are compared with those obtained using the conventional pure torsional shaft model. Geared tandem ship drive system is studied to test the reliability of the developments.
Using Chaos to Obtain Global Solutions in Computational Kinematics
Authors: Jovanovic Vojin T. , Kazerounian Kazem
Published: February 2021

In this paper we examine the sensitive dependence on the initial conditions of the Newton-Raphson search technique. It is demonstrated that this sensitivity has a fractal nature which can be effectively utilized to find all solutions to a nonlinear equation. The developed technique uses an important feature of fractals to preserve shape of basins of attraction on infinitely small scales.
A New Circuit Rectification Method in Four-Bar Linkages
Authors: Bawab Sebastian , Li Haitao
Published: February 2021

A circuit defect exists in four-bar linkages when a linkage cannot pass through all the design positions without being disassembled and reassembled in a different configuration. This paper describes a new and efficient procedure to rectify circuit defects in four-bar linkages at the synthesis level prior to the analysis level. It is achieved by controlling the change of sign of one of the angles opposite to the shortest link. The procedure utilizes the algebraic method where special points are employed to eliminate the solutions with circuit defects as a function of the design positions. Complete rectification is accomplished at the mid-synthesis level by controlling the critical angles of the linkage that identify the existence of circuit defects. This accounts for the rectification of circuit defects at the synthesis stage.
Kinetostatic Analysis for the Ross Yoke-Drive Stirling Engine
Authors: Williams Robert L.
Published: February 2021

This paper presents a complete rigid body dynamics model for the Ross yoke-drive mechanism which is used to transfer power in some Stirling engines. The kinematics model is derived, followed by the kinetics model. Results are given for a representative mechanism. The shaking force and moment results are compared with those predicted by a simplified model previously used for balancing design; a significant difference is demonstrated. In the future, the model presented in this paper will be used to design more effective balancing.
Systematic Enumeration of 1:1 Constant-Velocity Shaft Couplings
Authors: Tsai Lung-Wen , Madhavan Bharath
Published: February 2021

A systematic methodology is employed for the enumeration of 1:-1 constant-velocity shaft couplings. As a result, four potential 1:-1 constant-velocity shaft couplings that are free from singular conditions are enumerated. A promising mechanism is selected for the dynamic analysis. The analysis shows that the mechanism does have the potential for use as a 1:-1 constant-velocity shaft coupling and as a gearless differential.
A New Approach for Curvatures of Conjugate Surfaces
Authors: Chen Ningxin
Published: February 2021

A new and general approach for curvatures of conjugate surfaces is provided in this paper. The main characteristic of the approach is that relative curvatures and geodesic torsions of the conjugate surfaces are directly calculated in terms of the normal curvatures and geodesic torsions of the generating surface on two non-orthogonal tangents of surface curvilinears in global surface system. In comparison with the current approaches that use two orthogonal tangents or the principal directions in local system at each calculating point, the approach developed in this paper has a simple calculating process and a simple computer program. Based on the curvature equations, sliding velocities and sliding ratios of the conjugate surfaces are studied. The approach is illustrated by a numerical example of a plane enveloping globoidal wormgear drive.
Synthesis of Non-Uniform Stroke Piston Engines
Authors: Chew M. , Good T. A.
Published: February 2021

Piston engines have generally been designed with strokes that are uniform throughout the engine cycle. Variable-stroke engines have been designed with the capability to change the stroke lengths from cycle to cycle depending on load requirement. This article examines the synthesis of piston engines that are designed to have different stroke lengths and different relative stroke timing over an engine cycle. Such piston trajectories have been found to exhibit very high thermal efficiencies without resorting to high compression ratios. An investigation into different mechanisms and approaches toward the synthesis of such engine mechanisms is presented.
Workspace of a Gimbal With Joint Limits
Authors: Yeh Har-Jou , Abdel-Malek Karim A.
Published: February 2021

An analytical formulation for determining the workspace of a point on a body suspended in a Gimbal mechanism is presented. Although the gimbal mechanism comprises three degrees of freedom, the resulting workspace is a region on a spherical surface. The constraint function of the underlying mechanism is studied for singularities using a row-rank deficiency condition of its constraint Jacobian. Singular curves on the resultant spherical surface are determined by a similar analytical criterion imposed on the system’s subjacobian, to compute a set of two joint singularities. These singular curves define regions on the spherical surface that may or may not be accessible. A perturbation technique is then used to identify singular curve segments that are boundary to the workspace region. The methodology is illustrated through a numerical example.
A New Method for Displacement Analysis of Multi-Loop Spatial Linkages Based on Ordered Simple-Opened-Chains
Authors: Kong Xian-Wen , Yang Ting-Li
Published: February 2021

This paper presents systematically a new method for the displacement analysis (DA) of multi-loop spatial linkages (MLSLs) based on ordered simple-opened-chains (SOCs). In performing DA, a MLSL is converted into not a set of base points, a set of isolated links or a tree with/without isolated links in common use, but a weakly coupled MLSL in this paper. The characteristics of the proposed method are: (a) The number of unknowns in the set of equations for displacement analysis (EDA) of a MLSL is reduced to the minimum; (b) All the possible configurations corresponding to a given set of inputs of a weakly coupled MLSL or a strongly coupled MLSL with the coupled degree k = 1 can be obtained quickly. As compared with the other two methods available to find all the solutions to the DA in the case of MLSL with k = 1, the proposed method is superior to the resultant method in that it is applicable to more complex MLSLs and superior to the continuation method in that it takes much less CPU time to find all the solutions; (c) The set of EDA can be formulated and solved automatically; and (d) The new approach makes it possible to perform the kinematic and kineto-static analyses in a unified and simplified way.
Adhesive Performance of Quadruped Walking Vehicle With Pantograph Legs
Authors: Xu Peijun , Song Shin-Min
Published: February 2021

In this paper, the adhesive performance (walking without foot slippage) of quadruped walking vehicles with pantograph legs while walking on level ground was studied. The ground reactional forces acting on the feet at various body positions were computed using a compliant vehicle model. The effects of leg dimensions, leg mounting arrangements and gait parameters on the adhesive performance were then analyzed and methods to improve the adhesive performance were proposed.
Active Balancing of Joint Forces in High-Speed Linkages by Redundant Drives and Learning Control
Authors: Thuemmel Thomas , Brandl Marc
Published: February 2021

Critical loading and vibrations in high-speed linkages result from external forces at the output link and especially from varying inertia forces of irregular link motion. This paper deals with the active dynamic balancing of joint forces — Joint Force Control. Three possible balancing criterions indicated by joint forces are described: joint-stress, clearance-impact-noise and friction.

Active balancing requires additional drives. The two theoretical cases of arranging actuators are compared: redundantly and with an additional degree of freedom. Using the preferred redundant drives the internal forces in the joints may be varied according to special aims while the normal drive of the given mechanism maintains the motion.

An experimental setup consisting of a crank-and-rocker mechanism is used to study the control aim of a zero joint force at the crankshaft. The speed control of the original servo motor M1 is combined with the closed loop force control of the two redundant servo motors M2 and M3. Assuming a steady-state operation mode the learning control concept is applied successfully and compared with a digital PID force control. By learning control the time delay problem is solved. Furthermore the balancing of only one engine order is presented.
Comparison of Three Algorithms Using Thigh-Worn Accelerometers for Classifying Sitting, Standing, and Stepping in Free-Living Office Workers
Authors: Clark Bronwyn , Winker Elisabeth , Ahmadi Matthew , Trost Stewart
Published: February 2021

Accurate measurement of time spent sitting, standing, and stepping is important in studies seeking to evaluate interventions to reduce sedentary behavior. In this study, the authors evaluated the agreement in classification of these activities from three algorithms applied to thigh-worn ActiGraph accelerometers using predictions from the widely used activPAL device as a criterion. Participants (n = 29, 72% female, age 23–68 years) wore the activPAL3™ micro (processed by PAL software, version 7.2.32) and the ActiGraph™ GT9X accelerometer on the right front thigh concurrently for working hours on one full workday (7.2 ± 1.2 hr). ActiGraph output was classified via the three test algorithms: ActiGraph’s ActiLife software (inclinometer); an open source method; and, a machine-learning algorithm reported in the literature (Acti4). Performance at an instance level was evaluated by computing classification accuracy (F scores) for 15-s windows. The F scores showed high accuracy relative to the criterion for identifying sitting (96.7–97.1) and were 84.7–85.1 for identifying standing and 78.1–80.6 for identifying stepping. The four methods agreed strongly in total time spent sitting, standing, and stepping, with intraclass correlation coefficients of .96 (95% confidence interval [.92, .96]), .92 (95% confidence interval [.81, .96]), and .87 (95% confidence interval [.53, .95]) but sometimes overestimated sitting time and underestimated standing time relative to activPAL. These algorithms for identifying sitting, standing, and stepping from thigh-worn accelerometers provide estimates that are very similar to those obtained using the activPAL.
Examining the Contribution of Dog Walking to Total Daily Physical Activity Among Dogs and Their Owners
Authors: Potter Katie , Marcotte Robert T. , Petrucci Greg J. , Rajala Caitlin , Linder Deborah E. , Balzer Laura B.
Published: February 2021

Given high rates of obesity and chronic disease in both people and dogs, it is important to understand how dogs and dog owners influence each other’s health, including physical activity (PA) levels. Research suggests that dog owners who walk their dogs are more likely to meet PA guidelines than those who do not, but few studies have investigated dog walking intensity or its contribution to dog owners’ total moderate-to-vigorous PA using accelerometry. Furthermore, no studies have examined the contribution of dog walking to dogs’ total PA or the relationship between dog and dog owner PA using accelerometers on dogs. The authors used accelerometers on 33 dog owner–dog pairs to investigate (a) the intensity of dog walking behavior, (b) the contribution of dog walking to dog owners’ overall moderate-to-vigorous PA and dogs’ overall PA, and (c) the correlation between dog and dog owner PA. Dog owners wore an ActiGraph accelerometer and logged all dog walking for 7 days; dogs wore a Fitbark activity monitor. On average, 64.1% (95% confidence interval [55.2, 73.1]) of daily dog walking was moderate to vigorous intensity, and dog walking accounted for 51.2% (95% confidence interval [44.1, 58.3]) of dog owners’ daily moderate-to-vigorous PA. Dog walking accounted for 41.2% (95% confidence interval [36.0, 46.4]) of dogs’ daily PA. Dog owners’ daily steps were moderately correlated (r = .54) with dogs’ daily activity points. These findings demonstrate the interdependence of dog and dog owner PA and can inform interventions that leverage the dog–owner bond to promote PA and health in both species.
Massively parallel ultrafast random bit generation with a chip-scale laser
Authors: Kim Kyungduk , Bittner Stefan , Zeng Yongquan , Guazzotti Stefano , Hess Ortwin , Wang Qi Jie , Cao Hui
Published: February 2021

Laser-based generation of random numbers

The security of our digital networks is underpinned by the ability to generate streams of random numbers or bits. As networks expand in an ever-connected way, the challenge is to increase the generation rate of the random numbers to keep pace with demand. Kim
et al.
designed a chip-scale laser diode that generates random bits at an ultrahigh rate (see the Perspective by Fischer and Gauthier). By tailoring the geometry of the cavity, they were able to exploit the spatiotemporal interference of many lasing modes to generate picosecond-scale emission intensity fluctuations in space and time, producing ultrafast random bit streams in parallel. Such a device will find a wide range of applications requiring an ultrafast, compact, robust, and energy-efficient random bit generator.

Science
, this issue p.
948
; see also p.
889
Enhanced optical asymmetry in supramolecular chiroplasmonic assemblies with long-range order
Authors: Lu Jun , Xue Yao , Bernardino Kalil , Zhang Ning-Ning , Gomes Weverson R. , Ramesar Naomi S. , Liu Shuhan , Hu Zheng , Sun Tianmeng , de Moura Andre Farias , Kotov Nicholas A. , Liu Kun
Published: February 2021

Nanorod alignment for optical asymmetry

The high polarizability of chiral nanoassemblies of plasmonic nanoparticles can lead to strong chiral dichroism, but strong light scattering causes the fraction of polarized photons generated, as measured by g-factors, to be much lower than that for chiral liquid crystals. Lu
et al.
used supramolecular interactions of gold nanorods with human islet amyloid peptides to assemble metallic superstructures with unusually high cholesteric order (see the Perspective by Nam and Kim). The long, straight helices increased the g-factor by 4600-fold, and this effect was used to screen small-molecule binding to amyloids.

Science
, this issue p.
1368
; see also p.
1311
In the zone for liver proliferation
Authors: Andersson Emma R.
Published: February 2021

Distinct liver compartments contribute to hepatocyte homeostasis versus regeneration
Paul J. Crutzen (1933–2021)
Authors: Solomon Susan
Published: February 2021

Father of modern atmospheric chemistry
Differential Pathogenesis between Andes Virus Strains CHI-7913 and Chile-9717869 in Syrian Hamsters
Authors: Warner Bryce M. , Sloan Angela , Deschambault Yvon , Dowhanik Sebastian , Tierney Kevin , Audet Jonathan , Liu Guodong , Stein Derek R. , Lung Oliver , Buchanan Cody , Sroga Patrycja , Griffin Bryan D. , Siragam Vinayakumar , Frost Kathy L. , Booth Stephanie , Banadyga Logan , Saturday Greg , Scott Dana , Kobasa Darwyn , Safronetz David
Published: February 2021

Andes orthohantavirus (ANDV) is a New World hantavirus that is a major cause of hantavirus cardiopulmonary syndrome (HCPS; also referred to as hantavirus pulmonary syndrome) in South America, particularly in Chile and Argentina. ANDV is one of the few hantaviruses for which there is a reliable animal model, the Syrian hamster model, which recapitulates important aspects of human disease.
Subducting oceanic basement roughness impacts on upper-plate tectonic structure and a backstop splay fault zone activated in the southern Kodiak aftershock region of the Mw 9.2, 1964 megathrust rupture, Alaska
Authors: Krabbenhoeft Anne , von Huene Roland , Miller John J. , Klaeschen Dirk
Published: February 2021

In 1964, the Alaska margin ruptured in a giant Mw 9.2 megathrust earthquake, the second largest during worldwide instrumental recording. The coseismic slip and aftershock region offshore Kodiak Island was surveyed in 1977–1981 to understand the region’s tectonics. We re-processed multichannel seismic (MCS) field data using current standard Kirchhoff depth migration and/or MCS traveltime tomography. Additional surveys in 1994 added P-wave velocity structure from wide-angle seismic lines and multibeam bathymetry. Published regional gravity, backscatter, and earthquake compilations also became available at this time.

Beneath the trench, rough oceanic crust is covered by ∼3–5-km-thick sediment. Sediment on the subducting plate modulates the plate interface relief. The imbricate thrust faults of the accreted prism have a complex P-wave velocity structure. Landward, an accelerated increase in P-wave velocities is marked by a backstop splay fault zone (BSFZ) that marks a transition from the prism to the higher rigidity rock beneath the middle and upper slope. Structures associated with this feature may indicate fluid flow. Farther upslope, another fault extends >100 km along strike across the middle slope. Erosion from subducting seamounts leaves embayments in the frontal prism.

Plate interface roughness varies along the subduction zone. Beneath the lower and middle slope, 2.5D plate interface images show modest relief, whereas the oceanic basement image is rougher. The 1964 earthquake slip maximum coincides with the leading and/or landward flank of a subducting seamount and the BSFZ. The BSFZ is a potentially active structure and should be considered in tsunami hazard assessments.
UK paediatric oncology Pneumocystis jirovecii pneumonia surveillance study
Authors: Proudfoot Rebecca Hilary , Phillips Bob
Published: February 2021

Background

Pneumocystis jirovecii pneumonia (PJP) is a serious infective complication of immunosuppressive therapy. There are insufficient data concerning the incidence or mortality rate in children undergoing treatment for malignancies and how these may be influenced by prophylaxis.

Objective

Prospective collection of clinical information for all suspected and proven cases of PJP in children with cancer in the UK and Ireland.

Design

A surveillance survey was undertaken using a key contact at each paediatric oncology Principle Treatment Centre (PTC).

Main outcome measures

To describe the mortality, outcomes and use of prophylaxis in this at-risk group.

Results

The study confirms that PJP is rare, with only 32 cases detected in the UK over a 2-year period reported from all 20 PTCs. No deaths were directly attributed to PJP, in contrast to previously reported high mortality rates. Breakthrough infection may occur despite prescription of ostensibly adequate prophylaxis with co-trimoxazole; 11 such cases were identified. Six infections occurred in patients for whom prophylaxis was not thought to be indicated. Two infections occurred in patients for whom prophylaxis was specifically omitted due to concerns about potential bone marrow suppression or delayed engraftment.

Conclusion

PJP in children treated for malignant disease is rare. Breakthrough infection despite prophylaxis with co-trimoxazole may represent pathogen resistance or non-compliance. Further consideration of the use of PJP prophylaxis during acute myeloid leukaemia and non-Hodgkin’s lymphoma treatment is warranted, alongside appraisal of the clinical implications of the possible marrow suppressive effects of co-trimoxazole and its interactions with methotrexate.
Bidirectional temporal relationship between obesity and hyperinsulinemia: longitudinal observation from a Chinese cohort
Authors: Xu Chao , Zhou Guangshuai , Zhao Meng , Zhang Xu , Fang Li , Guan Qingbo , Zhang Haiqing , Gao Ling , Zhang Tao , Zhao Jiajun
Published: February 2021

Introduction

Although obesity and hyperinsulinemia are closely intercorrelated, their temporal sequence is still uncertain. This study aims to investigate the temporal relationship patterns between obesity measures and hyperinsulinemia in Chinese adults.

Research design and methods

The longitudinal cohort consisted of 2493 participants (860 males and 1633 female, mean age 56.71 years at follow-up) for whom measurements of obesity and hyperinsulinemia measures were collected twice between 2011 and 2014, with an average follow-up time of 3 years. Cross-lagged panel analysis was used to examine the temporal relationship between obesity measures (body mass index (BMI); waist circumference (WC); hip circumference (HC); waist-to-hip ratio (WHR)) and hyperinsulinemia (insulin, homeostasis model assessment of insulin resistance (HOMA-IR), or homeostasis model assessment of beta cell function (HOMA-%β)).

Results

After the adjustment of age, sex, smoking, drinking and follow-up years, in the BMI-insulin model, the path coefficient (β2=0.229; p<0.001) of baseline BMI to follow-up insulin was significantly greater than the path coefficient (β1=0.073; p<0.001) of baseline insulin to follow-up BMI (p<0.001 for β2>β1). In the WHR-insulin model, the path coefficient (β1=0.152; p<0.001) of baseline insulin to follow-up WHR was significantly greater than the path coefficient (β2=0.077; p<0.001) of baseline WHR to follow-up insulin (p=0.007 for β1>β2). In the WC/HC-insulin model, the path coefficients of baseline insulin to follow-up WC or HC (β1s) were also greater than the path coefficients of baseline WC or HC to follow-up insulin (β2s), but the difference between β1sand β2swere not significant. The similar temporal patterns were founded between obesity measures with HOMA-IR or HOMA-%β.

Conclusions

These findings indicate that there is a bidirectional relationship between obesity and hyperinsulinemia, and abdominal obesity measures are more sensitive to hyperinsulinemia measures than BMI.
Impact of COVID-19 on female fertility: a systematic review and meta-analysis protocol
Authors: Li Fangyuan , Lu Hua , Zhang Qi , Li Xinyun , wang Tong , Liu Qianchen , Yang Qian , Qiang Lingxia
Published: February 2021

Introduction

The increased social and economic burden caused by the novel COVID-19 outbreak is gradually becoming a worrisome issue for the health sector. The novel coronavirus invades the target cell by binding to ACE2, which is widely expressed in the ovaries, uterus, vagina and placenta. Significantly, the SARS-CoV-2 is said to interrupt female fertility through regulating ACE2. Thus, it is essential to investigate if the novel COVID-19 hampers female fertility, given that there is no systematic and comprehensive evidence on the association of COVID-19 with female fertility.

Methods and analysis

We will systematically search cohort studies, cross-sectional studies, case–control studies and self-controlled case series designs in the following databases: Web of Science, PubMed, EMBASE, Cochrane Library, Ovid, EBSCO, WHO COVID-19 Database, Chinese Biomedical Databases, China National Knowledge Internet, VIP and WanFang Database. Medical Subject Headings and free-text terms for “COVID-19” AND “female” AND “fertility” will be performed. Eligibility criteria are as follows: population (female patients aged 13–49 years); exposure (infection with SARS-CoV-2); comparison (population without SARS-CoV-2 infections or latent SARS-CoV-2 infections); and outcome (female fertility, such as ovarian reserve function, uterine receptivity, oviducts status and menstruation status). Article screening and data extraction will be undertaken independently by two reviewers, and discrepancies will be resolved through discussion. We will use the I2statistics to assess the heterogeneity and perform a meta-analysis when sufficiently homogeneous studies are provided. Otherwise, a narrative synthesis will be performed. We will explore the potential sources of heterogeneity using subgroup analyses and meta-regression.

Ethics and dissemination

Formal ethical approval is not required, and findings will be published in a peer-reviewed journal.

PROSPERO registration number

CRD42020189856.
Greenness may improve lung health in low–moderate but not high air pollution areas: Seven Northeastern Cities’ study
Authors: Zhou Yang , Bui Dinh S , Perret Jennifer L , Lowe Adrian J , Lodge Caroline J , Markevych Iana , Heinrich Joachim , Bloom Michael S , Knibbs Luke D , Jalaludin Bin , Yang Bo-Yi , Yu Hong-Yao , Zeng Xiao-Wen , Yu Yunjiang , Dharmage Shyamali C , Dong Guang-Hui
Published: February 2021

Introduction

There is growing interest in the impact of greenness exposure on airway diseases, but the impact of greenness on lung function in children is limited. We aimed to investigate the associations between greenness surrounding schools and lung function in children and whether these associations are modified by air pollution exposure.

Methods

Between 2012 and 2013, a cross-sectional survey and spirometry were performed among 6740 school children. Lung function patterns were determined as obstructive forced expiratory volume 1 s/forced vital capacity (FEV
1
/FVC <0.8) or restrictive (FEV
1
/FVC ≥0.8 but FVC <80% of predicted). School greenness was defined by Normalized difference vegetation index (NDVI) and soil-adjusted vegetation index. Nitrogen dioxide, sulphur dioxide and particular matter concentrations were assessed using a spatiotemporal model and national monitoring data. Two-level generalised linear models were used to investigate associations and interactions.

Results

Overall, an IQR in NDVI within 500 m was associated with higher FEV
1
(+57 mL 95% CI 44 to 70) and FVC (+58 mL 95% CI 43 to 73). NDVI was similarly associated with 25% reduced odds of spirometric restriction (OR: 0.75, 95% CI 0.65 to 0.86). However, among children exposed to the highest compared with the lowest quartile of particulate matter, increasing NDVI was paradoxically associated with lower −40 mL FVC (95% CI −47 to –33, p
interaction
<0.05).

Discussion

Our findings suggest that, in this study population, greening urban areas may promote lung health in low–moderate pollution areas but not in high air pollution areas. If the findings are replicated in other moderate-to-high pollution settings, this highlights a need to have a flexible green policy.
On quantum corrections to geodesics in de-Sitter spacetime
Authors: Emelyanov Viacheslav A.
Published: February 2021

We find a coordinate-independent wave-packet solution of the massive Klein–Gordon equation with the conformal coupling to gravity in the de-Sitter universe. This solution can locally be represented through the superposition of positive-frequency plane waves at any space-time point, assuming that the scalar-field mass M is much bigger than the de-Sitter Hubble constant H. The solution is also shown to be related to the two-point function in the de-Sitter quantum vacuum. Moreover, we study the wave-packet propagation over cosmological times, depending on the ratio of M and H. In doing so, we find that this wave packet propagates like a point-like particle of the same mass if $$M \ggg H$$

M
⋙
H

, but, if otherwise, the wave packet behaves highly non-classically.
A Framework for Cross-Industry Innovation: Transferring Technologies between Industries
Authors: Behne Alina , Heinrich Beinke Jan , Teuteberg Frank
Published: February 2021

Cross-industry innovation (CII) aims to reuse existing solutions by leveraging the innovative power of partners’ knowledge from another industry. CII is a key concept for identifying and adapting potential (disruptive) innovations and technologies and gains importance in recent years. To enable CII in companies, we examine the topic holistically. First, we summarize the existing literature, including frameworks of CII. Second, we conduct expert interviews in order to consider also the practical perspective. We then consolidate the results into a framework with a structured procedure and detailed methods, which can be used by companies. Our contribution has several implications for practice and research. For practice, we derive five recommendations for actions for companies that already use or plan to use CII. For the scientific community, we summarize the state of research on CII and present our framework, which can serve as a starting point for further research.
A Robust and Fast Image Encryption Scheme Based on a Mixing Technique
Authors: Heucheun Yepdia Lee Mariel , Tiedeu Alain , Kom Guillaume
Published: February 2021

This paper introduces a new image encryption scheme using a mixing technique as a way to encrypt one or multiple images of different types and sizes. The mixing model follows a nonlinear mathematical expression based on Cramer’s rule. Two 1D systems already developed in the literature, namely, the May-Gompertz map and the piecewise linear chaotic map, were used in the mixing process as pseudo-random number generators for their good chaotic properties. The image to be encrypted was first of all partitioned into N subimages of the same size. The subimages underwent a block permutation using the May-Gompertz map. This was followed by a pixel-based permutation using the piecewise linear chaotic map. The result of the two previous permutations was divided into 4 subimages, which were then mixed using pseudo-random matrices generated from the two maps mentioned above. Tests carried out on the cryptosystem designed proved that it was fast due to the 1D maps used, robust in terms of noise and data loss, exhibited a large key space, and resisted all common attacks. A very interesting feature of the proposed cryptosystem is that it works well for simultaneous multiple-image encryption.
Surgical Treatment of Ovarian Pregnancy
Authors: Thanasa Efthymia , Thanasas Ioannis , Koutalia Nikoleta , Mousia Maria
Published: February 2021

The description of this case concerns the early diagnosis and the surgical treatment of a patient diagnosed with an ectopic ovarian pregnancy. A gravida 2, para 0 woman with a history of termination of pregnancy in the second trimester, was referred to the outpatients of the Gynecologic Department of the General Hospital of Trikala, reporting vaginal bleeding, accompanied by a deep, mild pain in the abdomen for a few days. The urine pregnancy test was positive. The transvaginal ultrasound in combination with the β-chorionic gonadotropin level was indicative of an ectopic pregnancy, and the surgical treatment of the patient was decided. Intraoperatively, the presence of an ovarian ectopic pregnancy was detected, and a wedge resection of the affected ovary was performed. The patient was discharged from our clinic on the third postoperative day, with instructions for weekly follow-up of the β-chorionic gonadotropin level until it returns to normal values.
Long-Term Oncological Outcome Comparison between Intermediate- and High-Dose Radioactive Iodine Ablation in Patients with Differentiated Thyroid Carcinoma: A Propensity Score Matching Study
Authors: Kim Kwangsoon , Bae Ja Seong , Kim Jeong Soo
Published: February 2021

Background. Radioactive iodine (RAI) ablation is recommended for most patients with differentiated thyroid carcinoma (DTC) after total thyroidectomy (TT). We aimed to compare long-term outcomes between intermediate-dose (100 mCi) and high-dose (150 mCi) RAI ablation therapy in patients with DTC using propensity score matching analysis. Methods. This was a retrospective study of 1448 patients with DTC who underwent RAI ablation after TT. Propensity score matching was performed using the extent of operation, tumor size, extrathyroidal extension, multifocality, lymphatic invasion, vascular invasion, perineural invasion, number of positive lymph nodes (LNs), ATA risk stratification system, T stage, N stage, TNM stage, preoperative serum Tg and TgAb levels, and post-RAI serum Tg and TgAb levels. Results. Recurrence rates in the intermediate- and high-dose groups were 3.1% and 5.6%, respectively. After propensity score matching, LN ratio >0.22 (HR, 2.915; 95% CI, 1.228–6.918;

p
=
0.015

) and serum Tg >10 ng/mL after RAI (HR, 3.976; 95% CI, 1.839–8.595;

p
<
0.001

) were significant predictors of recurrence. Kaplan–Meier analysis showed no significant difference in DFS before or after propensity score matching (

p
=
0.074

and

p
=
0.378

, respectively). Conclusions. Intermediate-dose RAI ablation for the adjuvant treatment of DTC is sufficient as compared to high-dose RAI ablation. Further prospective or multicenter studies should be conducted to clarify the prognosis of intermediate-dose RAI ablation.
miR-126 Mimic Counteracts the Increased Secretion of VEGF-A Induced by High Glucose in ARPE-19 Cells
Authors: Sanguineti Roberta , Puddu Alessandra , Nicolò Massimo , Traverso Carlo Enrico , Cordera Renzo , Viviani Giorgio L. , Maggi Davide
Published: February 2021

Vascular endothelial growth factor-A (VEGF-A) has a pathologic role in microvascular diabetic complication, such as diabetic retinopathy (DR). miR-126 plays an important role in vascular development and angiogenesis by regulating the expression of VEGF-A. Since levels of miR-126 have been found downregulated in diabetes, this study is aimed at investigating whether hyperglycemia affects expression of miR-126 in a retinal pigment epithelium cell line. ARPE-19 cells were transfected with miR-126 inhibitor or with miR-126 mimic and the respective scramble negative control. After 24 hours, medium was replaced and cells were cultured for 24 hours in normal (CTR) or diabetic condition (HG). Then, we analyzed mRNA levels of miR-126, VEGF-A, PI3KR2, and SPRED1. We also evaluated protein amount of HIF-1α, PI3KR2, and SPRED1 and VEGF-A secretion. The results showed that exposure of ARPE-19 cells to HG significantly decreased miR-126 levels; mRNA levels of VEGF-A and PI3KR2 were inversely correlated with those of miR-126. Overexpression of miR-126 under HG restored HIF-1α expression and VEGF-A secretion to the level of CTR cells. These results indicate that reduced levels of miR-126 may contribute to DR progression by increasing expression of VEGF-A in RPE cells. In addition, we provide evidence that upregulation of miR-126 in RPE cells counteracts the rise of VEGF-A secretion induced by hyperglycemia. In conclusion, our data support a role of miR-126 mimic-approach in counteracting proangiogenic effects of hyperglycemia.
Clinical Significance of Screening Electrocardiograms for the Administration of Propranolol for Problematic Infantile Hemangiomas
Authors: Phillips James D. , Merrill Tyler , Gardner J. Reed , Thomas Collins R. , Sanchez Jenika , Johnson Adam B. , Eble Brian K. , Hartzell Larry D. , Kincannon Jay M. , Richter Gresham T.
Published: February 2021

Objective. Low-dose nonselective β blockade is an effective treatment for problematic infantile hemangioma (PIH). Screening electrocardiograms (ECG) are performed prior to the initiation of propranolol to minimize the risk of exacerbating undiagnosed heart block. How ECG results affect subsequent propranolol usage and patient management remains unclear. We examined the value of ECG prior to propranolol therapy in a quaternary pediatric hospital. Methods. A retrospective chart review was performed on all infants who received propranolol (2 mg/kg/day divided three times daily) to treat PIH at Arkansas Children’s Hospital from Sept. 2008 to Sept. 2015. All available demographic, historical, and clinical data were obtained. ECGs and echocardiographic data were reviewed and summarized. A pediatric cardiologist read all ECGs. Results. A total of 333 patients (75% female) received propranolol therapy. ECG information was available for 317 (95%). Abnormal findings were present on 44/317 (13.9%) of study ECGs. The most common abnormal finding was “voltage criteria for ventricular hypertrophy” (

n
=
35

, 76.1%). Two patients had abnormal rhythms; one had first-degree atrioventricular (AV) block, and one had occasional premature atrial contractions. Of the 31 patients who underwent echocardiograms, 20 (35%) were abnormal. 2.9% of infants with PIH treated with propranolol required a follow-up with a cardiologist. No patient was precluded from taking propranolol due to the findings on screening ECG. Conclusions. Screening ECGs prior to propranolol therapy are abnormal in nearly 14% of patients with PIH but are unlikely to preclude therapy. In the absence of prior cardiac history, this cohort offers further evidence suggesting that screening ECGs may be of limited value in determining the safety of propranolol in otherwise healthy infants with PIH.