bluuebunny/crossref_metadata_2025_split huggingface dataset:
An international comparison of anti‐SARS‐COV‐2 assays used for seroprevalence surveys from blood component providers
Authors: Lewin Antoine , Drews Steven J. , Lieshout‐Krikke Ryanne , Erikstrup Christian , Saeed Sahar , Faddy Helen , Uzicanin Samra , Custer Brian , O’Brien Sheila F ,   the Surveillance, Risk Assessment, Policy, the Virology Sub‐groups of the ISBT Transfusion Transmitted Infectious Diseases Working Party
Published: April 2021

Background and objectivesAccess to large pools of healthy adult donors advantageously positions blood component providers to undertake anti‐SARS‐CoV‐2 seroprevalence studies. While numerous seroprevalence reports have been published by blood operators during the COVID‐19 pandemic, details on the assay used has not been well documented. The objectives of this study were to evaluate the diversity of assays being used by blood operators and assess how this may affect seroprevalence estimates.Materials and methodsWe surveyed 49 blood component providers from 39 countries. Questionnaire included information on the number and identity of assays used, the detected immunoglobulin(s) and target antigen, and performance characteristics (sensitivity, specificity).ResultsThirty‐eight of the 49 contacted blood suppliers provided at least partial responses. The results indicate that 19 commercial and five in‐house serology assays have been used by surveyed blood operators. The Abbott SARS‐CoV‐2 IgG assay was the most commonly used kit and utilized by 15 blood suppliers. Two assays did not detect IgG, but detected either IgM/IgA or IgM. 68·2% of assays targeted the spike protein and 50% the nucleocapsid protein, while 18·2% targeted both viral proteins. The sensitivity and specificity of IgG‐specific assays ranged from 71·9% to 100% and from 96·2% to 100%, respectively. As of 18 October 2020, the seroprevalence was below 5% in 10 of 14 countries reporting.ConclusionOur results highlight the diversity of assays being used. Analyses comparing blood donor seroprevalence across countries should consider assay characteristics with optimization of signal/cut‐off ratios and consistent methodology to adjust for waning antibody.
AXIN1 knockout does not alter AMPK/mTORC1 regulation and glucose metabolism in mouse skeletal muscle
Authors: Li Jingwen , Knudsen Jonas R. , Henriquez‐Olguin Carlos , Li Zhencheng , Birk Jesper B. , Persson Kaspar W. , Hellsten Ylva , Offergeld Anika , Jarassier William , Le Grand Fabien , Schjerling Peter , Wojtaszewski Jørgen F.P. , Jensen Thomas E. 
Published: April 2021

Key points
Tamoxifen‐inducible skeletal muscle‐specific AXIN1 knockout (AXIN1 imKO) in mouse does not affect whole‐body energy substrate metabolism.
AXIN1 imKO does not affect AICAR or insulin‐stimulated glucose uptake in adult skeletal muscle.
AXIN1 imKO does not affect adult skeletal muscle AMPK or mTORC1 signalling during AICAR/insulin/amino acid incubation, contraction and exercise.
During exercise, α2/β2/γ3AMPK and AMP/ATP ratio show greater increases in AXIN1 imKO than wild‐type in gastrocnemius muscle.
AbstractAXIN1 is a scaffold protein known to interact with >20 proteins in signal transduction pathways regulating cellular development and function. Recently, AXIN1 was proposed to assemble a protein complex essential to catabolic‐anabolic transition by coordinating AMPK activation and inactivation of mTORC1 and to regulate glucose uptake‐stimulation by both AMPK and insulin. To investigate whether AXIN1 is permissive for adult skeletal muscle function, a phenotypic in vivo and ex vivo characterization of tamoxifen‐inducible skeletal muscle‐specific AXIN1 knockout (AXIN1 imKO) mice was conducted. AXIN1 imKO did not influence AMPK/mTORC1 signalling or glucose uptake stimulation at rest or in response to different exercise/contraction protocols, pharmacological AMPK activation, insulin or amino acids stimulation. The only genotypic difference observed was in exercising gastrocnemius muscle, where AXIN1 imKO displayed elevated α2/β2/γ3 AMPK activity and AMP/ATP ratio compared to wild‐type mice. Our work shows that AXIN1 imKO generally does not affect skeletal muscle AMPK/mTORC1 signalling and glucose metabolism, probably due to functional redundancy of its homologue AXIN2.
A quantitative description of macaque ganglion cell responses to natural scenes: the interplay of time and space
Authors: Schottdorf Manuel , Lee Barry B. 
Published: April 2021

Key points
Responses to natural scenes are the business of the retina. We find primate ganglion cell responses to such scenes consistent with those to simpler stimuli. A biophysical model confirmed this and predicted ganglion cell responses with close to retinal reliability.
Primate ganglion cell responses to natural scenes were driven by temporal variations in colour and luminance over the receptive field centre caused by eye movements, and little influenced by interaction of centre and surround with structure in the scene.
We discuss implications in the context of efficient coding of the visual environment. Much information in a higher spatiotemporal frequency band is concentrated in the magnocellular pathway.
AbstractResponses of visual neurons to natural scenes provide a link between classical descriptions of receptive field structure and visual perception of the natural environment. A natural scene video with a movement pattern resembling that of primate eye movements was used to evoke responses from macaque ganglion cells. Cell responses were well described through known properties of cell receptive fields. Different analyses converge to show that responses primarily derive from the temporal pattern of stimulation derived from eye movements, rather than spatial receptive field structure beyond centre size and position. This was confirmed using a model that predicted ganglion cell responses close to retinal reliability, with only a small contribution of the surround relative to the centre. We also found that the spatiotemporal spectrum of the stimulus is modified in ganglion cell responses, and this can reduce redundancy in the retinal signal. This is more pronounced in the magnocellular pathway, which is much better suited to transmit the detailed structure of natural scenes than the parvocellular pathway. Whitening is less important for chromatic channels. Taken together, this shows how a complex interplay across space, time and spectral content sculpts ganglion cell responses.
An Estimate of the Bound of the Lyapunov Exponents for Caputo–Hadamard Fractional Differential System
Authors: Li Changpin , Yin Chuntao 
Published: April 2021

Abstract
This paper is devoted to estimating the bound of the Lyapunov exponents for the Caputo–Hadamard fractional differential system. First, using the Gronwall inequality, we analyze the continuous dependence of the solution to the Caputo–Hadamard fractional initial value problem (IVP). Then, we define the Lyapunov exponents for the Caputo–Hadamard fractional differential system and estimate their bounds. Besides, numerical examples are displayed which support the theoretical results.
NWRAG, a New Algorithm for Structural Optimization
Authors: No M. , Aguinagalde J. M. 
Published: April 2021

Abstract
This paper presents an algorithm to solve the optimum design problem for general structures. The algorithm is based on the solution of the nonlinear system of equations derived from the Kuhn-Tucker optimality conditions. Sets of active design variables and active behaviour constraints are used. Some practical examples are presented to show how NWRAG performs better than other optimality criterion based algorithms for structures involving bending effects.
Position and Motion Planning in a Confined Region via Nonlinear Programming
Authors: Mayne R. W. 
Published: April 2021

Abstract
This paper describes the formulation of a position and motion planning problem in an optimization setting. Emphasis is placed on planning movements in a confined workspace where contacts must be avoided. The formulation includes the possibility of extra degrees of freedom and is demonstrated in detail on a simple robot problem. Robot positioning and trajectory planning are considered within a two dimensional workspace and a recursive quadratic programming procedure is used for the optimization. The results presented herein show satisfactory performance and considerable promise for extension to more complex configurations and three dimensions.
Optimal Valve Lift Curve Design for Valve Train Cam Systems
Authors: Chan C. , Pisano A. P. 
Published: April 2021

Abstract
The design of valve lift curves for valve train cam systems is formulated as an optimization problem, in which the maximum principle is applied. The solution is obtained by utilizing the maximum principle approach for an equivalent linear quadratic optimal control problem. The outcome of the design shows trade-offs between several design criteria. The method is applied to the specification of the lift curve for a finger-follower cam system, and design charts are developed for different choices of design parameters. The method presented in this study provides a unified way of valve lift curve design for those cam systems where the objective functions can be clearly defined.
Analysis and Optimal Design of Spatial Mechanical Systems
Authors: Ashrafeiuon H. , Mani N. K. 
Published: April 2021

Abstract
This paper presents a new approach to optimal design of large multibody spatial mechanical systems. This approach uses symbolic computing to generate the necessary equations for dynamic analysis and design sensitivity analysis. Identification of system topology is carried out using graph theory. The equations of motion are formulated in terms of relative joint coordinates through the use of velocity transformation matrix. Design sensitivity analysis is carried out using the Direct Differentiation method applied to the relative joint coordinate formulation for spatial systems. Symbolic manipulation programs are used to develop subroutines which provide information for dynamic and design sensitivity analysis. These subroutines are linked to a general purpose computer program which performs dynamic analysis, design sensitivity analysis, and optimization. An example is presented to demonstrate the efficiency of the approach.
Supercomputer-Based Sensitivity Analysis of Constrained Dynamic Systems
Authors: Krishnaswami P. , Ramaswamy S. 
Published: April 2021

Abstract
Generalized design sensitivity analysis of constrained dynamic systems is a computationally intensive process that is well-suited for implementation on a modern supercomputer. A matrix oriented method for design sensitivity analysis, based on direct differentiation, is developed. An algorithm based on this development was implemented in a computer code which was then run on a Cray X-MP supercomputer. The implementation attempts to make full use of the vectorization capabilities of this machine. The numerical examples that were run on this implementation were compared with results presented in the literature in order to verify the program and to assess its computational performance.
The results show that the use of supercomputers for performing design sensitivity analysis of dynamic systems using this method produces a dramatic reduction in the computing time; it is anticipated that this will make the optimization of very large-scale dynamic systems computationally viable.
Goal Programming Approach for the Balancing of Variable Input Speed Mechanisms
Authors: Kaplan R. L. , Rao S. S. 
Published: April 2021

Abstract
The minimization of the dynamic reactions of high speed, variable input speed planar mechanisms is considered using multiobjective nonlinear programming techniques. A general procedure, which can easily incorporate variable angular velocity input, joint friction and external loading, is used for the dynamic analysis of the mechanisms. A goal programming approach is outlined for the solution of the optimization problem. This procedure is coupled with an exterior penalty function approach in developing the necessary computer program. An example four-bar linkage is considered for illustration. It is observed that the approach presented in this paper offers greater flexibility and wider application in the optimal balancing of high speed linkages.
Optimization of the Control Function for a Footless Biped in a Stationary, Upright Posture
Authors: Hsu M. S. , De Spain M. , Shaw J. , Mulder M. , Wagner N. 
Published: April 2021

Abstract
The stability of a footless biped in a stationary, upright posture is studied on the sagittal plane using two and three link models. Closed form expression of the stability range for the control gains is derived from Routh-Hurwitz criteria. Evaluation and optimization of the multiple gain systems are realized using statistical and numerical techniques. The optimal control gains are obtained and the gain-locus is derived. The algorithm for optimizing the control function is provided and several numerically derived examples are illustrated.
Engineering of Flexible Software for Real-Time Systems
Authors: Schmuter S. L. , Hamidieh Y. A. 
Published: April 2021

Abstract
Flexibility of software for real-time control of machinery becomes one of the major objectives in view of ever increasing software costs. Such flexibility promotes efficiency in the development stage, but even more so, it enhances maintainability and facilitates upgrade during retooling and job changeover. A multilevel organization of software is described whereby the computational units in a particular level perform a special class of tasks and have specific privileges assigned to that level. A slot-matrix frame of the top control level along with a knowledge base provides for flexible chaining of various functions from the levels below, thus allowing substantial new features to be incorporated into the system if and when required. At the interactive level, selection alternatives for the operator are intelligently inferred and displayed through a rule base, and inputs are interpreted. The entire software is embedded in a number of processes for off-line computations, real-time control, transformations and data transfer. An example for robotic applications is elaborated.
Fault Tree Approach for the Reliability Analysis of Gear Trains: Part II — Example Applications
Authors: Pan T. S. , Rao S. S. 
Published: April 2021

Abstract
The application of fault tree techniques to the analysis of gear trains is considered. The techniques involve the decomposition of the system into a logic diagram or fault tree in which certain basic or primary events lead to a specified top event which signifies the total failure of the system. The fault trees are used to obtain minimal cut sets from which the modes of system failure and hence the reliability measure for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through a nine speed compound gear train and a five speed epicyclic gear train.
Some Design Considerations for Computer Controlled Inspection (CCI) Systems in Statistical Process Control (SPC) Applications
Authors: Shaikh R. A. 
Published: April 2021

Abstract
US manufacturers are under siege from the extreme foreign competition. So it is little wonder that domestic producers are renewing their commitment to quality. And the key to higher quality is automation. Consistency and accuracy generally improves when automated machines producing parts remain in proper order. An automated system producing off specs. parts will do so with the same consistency it produces correct output, this time not only it produces scrap, but produces it faster. Therefore, automated inspections and Computer Aided Quality Engineering (CAQE), that integrates with all the other factory automation manufacturing functions seem to be the most viable solution to meet the quality challenge.
This paper outlines the importance of SPC in the automation environments, and describes some design concepts for the development and implementation of CCI systems. Typical design applications and future trends are discussed. The paper concludes with suggestions for effective implementation of CCI systems.
Two Generalizations of the Isometric Projection in Geometric Design
Authors: Wilde D. J. 
Published: April 2021

Abstract
The well-known pictorial drafting technique of isometric drawing is here generalized in two ways, called “isoclinal” and “axial”, or collectively, “symmetric”. Although the isoclinal projection preserves the useful property of foreshortening adjacent edges equally, and the axial projection foreshortens adjacent edges equally, the directions for these projections usually differ from that for isometric projection. Formulas are derived for the isoclinal and axial directions and their foreshortening factors and rotation matrices. Although intended for three-dimensional computer-aided design, the symmetric projections can also be performed on a drawing board with a protractor. Graphic examples involving design of non-rectangular connectors for three skew structural members and adjacent plates in space are presented.
Computer Graphics and Analysis in Elastomeric Compact Seal Design
Authors: Johannesson H. L. 
Published: April 2021

Abstract
The use of advanced calculations are necessary in elastomeric seal design if the today situation of “trial and error” shall be avoided. In order to make it easy for the designer to carry out these calculations, computer graphics can be used together with calculation programs.
In this work it is shown how a general purpose turn-key CAD-system can be used together with complex calculation programs in elastomeric compact seal design. It is demonstrated how communication between the CAD-system and the calculation program can be established with the use of the “graphic application programming language” that must be available within the CAD-system.
The suggested computer aided design procedure is especially suitable for products like seals, which have simple geometry but require complicated calculations.
Integration of Expert System Into a CAD System of Springs
Authors: Jin Yu , Shihua Liu , Jing Qin , Ji Zhou 
Published: April 2021

Abstract
By combining the reasoning design of the expert system with the analysis and calculation of spring based on a mathematical model and its optimal design, an intelligent spring CAD system has been established. The expert system technique is adopted for such non-calculating designing steps as the selection of scheme, the determination of parameters as well as for the development of the technological process, thus greatly strengthening the original CAD system of springs. This paper provides a detailed description of the function, structure, characteristic features and significance of the said system.
Reliability Analysis of Robot Manipulators
Authors: Bhatti P. K. , Rao S. S. 
Published: April 2021

Abstract
A probabilistic approach to robot kinematics is presented and the concept of manipulator reliability is introduced to obtain a better evaluation of the performance of manipulators. Techniques are presented to compute this reliability and its relationship to the geometric parameters such as tolerances and arm configuration are discussed. The aspects of accuracy and repeatability of manipulators are explained in terms of manipulator reliability. The reliability of a two-link planar manipulator and the Stanford arm are considered for numerical illustration.
Some Properties of a New Kinematic Structure for Robot Manipulators
Authors: Stoughton R. , Kokkinis T. 
Published: April 2021

Abstract
A 3 DOF closed chain kinematic structure particularly well suited to robot manipulators is explored. The structure has a number of distinct geometries, two of which are analyzed to reveal the geometric and Jacobian relationships, singularities and the workspace volume. These relationships are found to be much simpler than for other parallel actuated spatial structures with 3 or more DOFs. The geometries studied can have large workspace volumes. An optimization procedure is applied to select link lengths for which the Jacobian is relatively homogeneous. Singularities can be restricted to the boundary of the workspace. The proposed geometries can achieve speeds and accuracies unattainable with similar serial link designs.
On the Equations of Motion for Robot Arms and Open Kinematic Chains
Authors: Gupta S. , Townsend M. A. 
Published: April 2021

Abstract
The closed-form equations of motion for robot arms and other open kinematic chains are derived using the Newton-Euler equations in a form particularly suitable for the automatic modeling and on-line control of such mechanisms. The approach is based on Vukobratovic’s method (3), using more conventional Western notation.
Automated Modeling and Rapid Solution of Robot Dynamics Using the Symbolic Polynomial Technique
Authors: Townsend M. A. , Gupta S. 
Published: April 2021

Abstract
Fast and accurate solutions of the dynamic equations of a robot arm are required for real time on-line control. In this paper we present a new method for rapidly evaluating the exact dynamic state of a robot. This method uses a combination of symbolic and numerical computations on the equations of motion, which are developed in the form of polynomials — hence the name, the symbolic polynomial technique.
Dynamic Modeling of a Multi-Legged Robotic Vehicle: Part 1 — Kinematic Analysis
Authors: Hart R. A. , Ebrahimi N. D. 
Published: April 2021

Abstract
This two-part paper presents a dynamic model of a legged vehicle for travel on a variable-topographic terrain. In Part 1 of the paper, we develop expressions for the kinematics of the vehicular system. These expressions, in turn, form the foundation for the dynamic analysis of the robotic vehicle presented in Part 2 of the paper. The model applies to a system composed of a cargocarrying body supported by four multi-degree-of-freedom linkage assemblies whose configurations are adjustable to accommodate terrain irregularities. The mobility of the locomotion system is provided by four rigid wheels which serve as a base to the kinematic chains that extend from the platform of the vehicle. To assure dynamic equilibrium of all members in the system, torque actuators are employed at the joints between inter-connecting bodies to facilitate the adjustment of each articulated chain configuration without reducing the adaptability of the vehicle to ground profile variations. The dynamic model used for determining the system response to environmental contact forces is based on a Newton-Euler recursive formulation.
The Design of Three Jointed Two-Degree-of-Freedom Robot Fingers
Authors: Leaver S. O. , McCarthy J. M. 
Published: April 2021

Abstract
The design of modern mechanical hands requires a choice for the kinematic structure of the finger. The typical finger is a planar manipulator with one, two, or three independently controllable joints. Each controllable joint requires a motor and sensor system which increases the weight of the hand. There is a desire to minimize the number of degrees of freedom in a mechanical hand because the payload capacity of a manipulator is limited. Two degrees of freedom provides the required positioning capability of a finger tip (though not the ability to control contact angle). Three joints are required to provide the ability to enclose grasped objects. This paper considers the design of fingers which are planar manipulators with three joints but only two degrees of freedom. In addition to the fully coupled design, twelve classes of finger designs with varying degrees of de-coupling are presented. It happens that one of these classes includes the human finger, a mechanical model of which is presented in detail.