bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Fabrication of Microelectromechanical Systems
Authors: Ananthasuresh G. K. , Kota Sridhar , Crary Selden B. , Wise Kensall D.
Published: March 2021

An attempt has been made to summarize some of the important developments in the emerging technology of microelectromechanical systems (MEMS) from the mechanical engineering perspective. In the micro domain, design and fabrication issues are very much different from those of the macro world. The reason for this is twofold. First, the limitations of the micromachining techniques give way to new exigencies that are nonexistent in the macromachinery. One such difficulty is the virtual loss of the third dimension, since most of the microstructures are fabricated by integrated circuit based micromachining techniques that are predominantly planar. Second, the batch-produced micro structures that require no further assembly, offer significant economical advantage over their macro counterparts. Furthermore, electronic circuits and sensors can be integrated with micromechanical structures. In order to best utilize these features, it becomes necessary to establish new concepts for the design of MEMS. A set of key joints and mechanisms using which majority of the mechanical devices can be built, is identified. It is surmised that such an effort will be advantageous in designing micromechanisms as they form the basis for what we call fabrication building blocks (joints) and synthetic building blocks (mechanisms). The paper also reviews some of the fabrication techniques and the micromechanical devices that have already been made, and makes suggestions regarding the fabrication of a few generic mechanisms that can be made using these techniques. In particular, it discusses the fabrication of a motor-driven four-bar linkage using the “boron-doped bulk-silicon dissolved-wafer process” developed at The University of Michigan’s Center for Integrated Sensors and Circuits.
A Singularity Avoiding Kinematic Solution for a Four-Jointed Robot Wrist Using Heuristic Algorithm
Authors: Lee Wei-Ming
Published: March 2021

In this paper, a heuristic, singularity avoiding, trajectory generation algorithm is developed to solve the singularity problem of a four-jointed robot wrist. Starting from the inverse velocity solutions, a reduced Jacobian matrix is composed to map the system between the joint space and workspace. Six linear combinations of the joint rates are constructed to be used as a family of constraint functions. The forecasting function is very important in the whole algorithm. It is necessary to know in advance if the system is going into or near a singular configuration. The algorithm will determine through forecasting whether to switch from the current constraint function to another which possesses the smallest maximum joint velocity during the forecasting time interval. Trajectories which partially cover the wrist workspace are generated to prove singularity avoidance. The numerical result is shown in the maximum of the min-max joint velocity in different time intervals. It is indicated that the forecasting time interval will effect the singularity avoidance.
Workspace Evaluation of Stewart Platforms
Authors: Masory Oren , Wang Jian
Published: March 2021

The workspace and the dexterity of a Stewart Platform are effected by the choice of its major dimensions, actuators’ stroke and the kinematic constraints of its joints. An investigation of the effects of these parameters on workspace volume of the platform is presented. The obtained results were normalized so that these can be used as a design tool for the selection of dimensions, joints and actuators.
Structural Parameters Which Reduce the Number of Manipulator Configurations
Authors: Mavroidis Constantinos , Roth Bernard
Published: March 2021

The inverse kinematics of series-chain, six-degree-of-freedom manipulators has been developed to the point where it yields all possible configurations for a given end-effector position and orientation. In this paper we use the methods of inverse kinematics to uncover the conditions on the structural parameters which cause a manipulator to yield a lower maximum number of configurations than its general class. It is shown that the following conditions can cause a diminution In the maximum number of possible configurations: parallel joint axes, perpendicular joint axes, intersecting joint axes, and Bennett geometries. Using these geometries in 6R, 5R1P, 4R2P and 3R3P chains, this paper determines the reduction in degree of their characteristic polynomials.
Extrinsic Calibration of Portable Manipulators
Authors: Shooter Steven B. , Reinholtz Charles F.
Published: March 2021

Portable manipulators are installed for operation and then removed upon completion of their task. Typical applications of portable manipulators include the inspection of nuclear reactors, inspection and repair of nuclear steam generators and asbestos removal in buildings. In such operations, it is difficult to precisely position the manipulator at a fixed location within its workplace, yet this is critical for accurate tool positioning. It can be possible, however, to position the tool tip at several points in the environment using video feedback and manual operator control of the manipulator. This provides sufficient information to determine the position and orientation of the manipulator base frame with respect to the environment, hereafter referred to as extrinsic calibration. Following extrinsic calibration, subsequent moves of the manipulator can be automated. This paper describes a closed-form method for performing extrinsic calibration by contacting the tool to a total of six places on three orthogonal plane surfaces of reference.
Mechanical Design and Kinematic Analysis of a Three-Legged Six Degree-of-Freedom Parallel Manipulator
Authors: Zlatanov D. , Dai M. Q. , Fenton R. G. , Benhabib B.
Published: March 2021

In this paper a three-legged 6-dof platform-type parallel manipulator is described. Each of the legs is a serial subchain with three revolute joints connected to the output platform via a spherical joint. Due to the proposed asymmetrical 3-2-1 distribution of the controlled joints, a closed-form solution exists to the forward kinematics problem. The mechanical design of the manipulator has been developed. The forward and inverse kinematics as well as the instantaneous kinematics of the mechanism have been solved analytically.
Walking Machine Design Based on Certain Aspects of Insect Leg Design
Authors: Fichter E. F. , Kerr D. R.
Published: March 2021

A walking machine design originating from observations of insects is presented. The primary concept derived from insects is a leg used to apply force to the body without applying significant moments about the point of body attachment. This is accomplished with legs which have kinematic equivalents to ball-and-socket joints at body attachment and ground contact, with joints in the middle which only change distance between body and ground. Standing and walking with 6 legs of this design requires careful attention to static equilibrium equations but does not necessitate a control system which actively distributes forces to the legs. This paper considers necessary observational data, assumptions on which control is based, mathematical development for control and problems such as foot slip.
A Complex Number Approach for Absolute Precision Position Synthesis for Three Precision Positions
Authors: Mirth John A.
Published: March 2021

Dyads can be synthesized by prescribing the precision point coordinates and the absolute planar orientations of one dyad vector at each of three precision positions. This differs from traditional complex number methods wherein the vector orientations are described relative to one another. Absolute precision position synthesis can be performed for both motion generation, and path generation with prescribed timing. The method presented uses vector loop equations and complex number notation to produce a closed form solution for the three absolute precision position problem. Absolute precision position synthesis is applicable to cases that require specific coupler geometries. The synthesis of flat-folding mechanisms is an example of one such application.
A Dyad Search Algorithm for Solving Planar Linkages Using the Dyad Method
Authors: Romdhane Lofti
Published: March 2021

Based on graph representation of planar linkages, a new algorithm was developed to identify the different dyads of a mechanism. A dyad or class II group, is composed of two binary links connected by either a revolute (1) or a slider (0) pair with provision for attachment to other links by lower pair connectors located at the end of each link. There are five types of dyads: the D111, D101, D011, D001, and D010. The dyad analysis of a mechanism is predicated on the ability to construct the system from one or more of the five binary structure groups or class II groups. If the mechanism is complicated and several dyads are involved, the task of identifying these dyads by inspection could be difficult and time consuming for the user. This algorithm allows a complete automation of this task. This algorithm is based on the Dijkstra’s algorithm, for finding the shortest path in a graph, and it is used to develop a computer program, called KAMEL: Kinematic Analysis of MEchanical Linkages, and implemented on an IBM-PC PS/2 model 80. When compared to algorithmic methods, like the Newton-Raphson, the dyad method proved to be a very efficient one and requires as little as one tenth of the time needed by the method using Newton-Raphson algorithm. Moreover, the dyad method yields the exact solution of the position analysis and no initial estimates are needed to start the analysis. This method is also insensitive to the value of the step-size crank rotation, therefore, allowing a very accurate and fast solution of the mechanism at any position of the input link.
Joint Rotation Space of Five-Bar Linkages
Authors: Ting Kwun-Lon , Shyu J. H.
Published: March 2021

Unlike single degree of freedom linkages, the rotatability at a joint of a five-bar linkage is affected by the rotatability at another joint. Unless the linkage has full rotatability, the allowable inputs of a five-bar linkage are related. This article, by taking the interrelationship between the rotatability of two input angles into consideration, presents the most extensive study on the rotatability of five-bar linkages. The joint rotation space of a five-bar linkage is the region between the singular curves which represent the relationship between the input angular positions of the linkage at singular positions. By distinguishing five-bar linkages into C-C (crank-crank), C-R (crank-rocker), and R-R (rocker-rocker) types, there are totally nine C-C types, four C-R types and four R-R types of joint rotation space in classes I and II five-bar linkages. The results in this paper are essential for understanding the basic mobility and limitation of five-bar linkages. One may also find them useful in manipulators or multi-loop linkages which have a five-bar chain as the major or minor structure. The results are also applicable to spherical five-bar linkages.
Synthesis of Mechanisms Including Circuit Defects, Branch Defects and Input-Crank Rotatability
Authors: Cheng Jyun-Cheng , Kohli Dilip
Published: March 2021

In this paper, an analytical method is developed for synthesizing linkages (with a quadratic input-output equation) which are free from circuit and branch defects and, in addition, may be required to have fully rotatable cranks. A novel concept called the range defect of the input link is introduced. It is shown that the range defect results in a circuit defect. Further, all circuit defects except those introduced as a result of range defects can be eliminated by eliminating branch defects. The circuit defect introduced by the range defect is eliminated by first eliminating the range defect and then eliminating the branch defect. Inequalities are developed as a function of mechanism design variables which represent the existence of range defects and therefore a possible circuit defect. The circuit defect identifiers are then developed and used in the synthesis of function generating planar four-bar and spatial RSSR linkages. The method developed is general and is applicable to any mechanism with a quadratic input-output equation such as RSSP, spherical 4-bar and 4R3P linkages.
Identification of Flexible Link Dynamics Using Neural Networks
Authors: D’Arcangelis Lawrence , Nair Satish S.
Published: March 2021

Multilayered neural networks have found widespread use in the identification and control of dynamic systems. This study considers modeling issues for two time scale systems using neural networks for reliably estimating gradients for on-line control purposes. A structure for identification of a single link flexible arm is proposed and preliminary results are presented.
New CAD Approaches in Research and Teaching for the Design of Non-Uniform Motion Mechanisms
Authors: Funk Wolfram
Published: March 2021

This paper presents a program for the synthesis of four-bar linkages which is part of an overall system for the analysis and synthesis of mechanisms. The kinematics of a thick-walled oven door are used as an example.
Mechanisms of the Ancient Greek Theater
Authors: Dimarogonas Andrew D.
Published: March 2021

The word Mechanism is a derivative of the Greek word mechane (which meant machine, more precisely, machine element) meaning an assemblage of machines. While it was used for the first time by Homer in the Iliad to describe the political manipulation, it was used with its modern meaning first in Aeschylos times to describe the stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term Deus ex machina. At the same time, the word mechanopoios, meaning the machine maker or engineer, was introduced for the man who designed, built and operated the mechane.

None of these machines, made of perishable materials, is extant. However, there are numerous references to such machines in extant tragedies or comedies and vase paintings from which they can be reconstructed: They were large mechanisms consisting of beams, wheels and ropes which could raise weights up-to one ton and, in some cases, move them back-and-forth violently to depict space travel, when the play demanded it. The vertical dimensions were over 4 m while the horizontal travel could be more than 8 m.

They were well-balanced and they could be operated, with some exaggeration perhaps, by the finger of the engineer. There is indirect information about the timing of these mechanisms. During the loading and the motion there were specific lines of the chorus, from which we can infer the duration of the respective operation.

The reconstructed mechane is a spatial three- or four-bar linkage designed for path generation.
The Synthesis of Cam-Oscillating Roller-Follower Mechanisms: A Unified Approach
Authors: González-Palacios Max Antonio , Angeles Jorge
Published: March 2021

A unified approach to the synthesis of the contact surface of cam-oscillating roller-follower mechanisms is presented. This is achieved using dual numbers. The surfaces of both cam and roller are obtained so that, at their contact line, a minimum-magnitude sliding velocity is produced. The differential geometry of the pitch surface and the pressure angle are both analyzed.
Multiloop Spatial Kinematic Analysis Based on the Joint Displacement Method
Authors: Yang Yu-Neng , Chieng Wei-Hua , Hoeltzel David A.
Published: March 2021

To accelerate the design automation process for the spatial mechanism design, this paper presents an efficient kinematic analysis method, called the joint displacement method. Based on this method, the kinematic analysis for a seven-link, two-loop spatial RSCC-SRR mechanism can be accomplished in 1.52 second on a PC/486-based computer for a complete 60-steps (6 degrees/step) crank-revolution. This method is applicable for both single-loop and multiloop spatial mechanisms with revolute, cylindrical, translational, spherical and universal joints, with the high computational efficiency which hasn’t been found in the literatures. The general purpose computer program coded in C language has been tested with a wide variety of mechanisms, which produces very satisfactory results.
A Dynamic Implementation of Keller’s Sketching Rules for Burmester Curves an Approach to Sensitivity Analysis
Authors: Nisbett J. Keith , Gupta Sanjay K.
Published: March 2021

Keller’s sketching rules for Burmester curves are implemented on the computer for automatic generation of valid and invalid regions for the existence of the curves. The rules are based on the poles of the coupler motion, which in turn are directly related to the precision positions. All six possible unique arrangements of poles are used in the sketching rules. The sketching rules provide a useful heuristic and geometric approach to relating the sensitivity of the curves to small changes in the pole locations. The regions and the curves are dynamically updated as the poles of the specified motion are moved by the user. The new curve obtained is checked to verify satisfaction of original tolerance specification on the precision positions. The procedure shows promise for artificially intelligent approaches to linkage design.
Kinematic Transformation Matrices for 3D Surface Contact Joints
Authors: Gutkowski L. J. , Kinzel Gary L.
Published: March 2021

A generalized procedure is presented for the development of a pair matrix that describes kinematic joints formed by contact between three-dimensional surfaces. The pair matrix is useful in the matrix-based kinematic analysis procedure put forth by Sheth and Uicker (1971) previously. Any two surfaces may make up the joint as long as the surfaces can be described parametrically, and contact takes place at one point. The corresponding pair matrix is a function of five pair variables.
The Optimal Design of Mechanisms Employing a Synthesis Based Merit Function
Authors: Gold Christian H. , Derby Stephen J.
Published: March 2021

A method of implementing three-precision point synthesis into the merit function of kinematic optimization problems was developed. The addition of synthesis reduced the order of the merit function from eight to four. The new merit function was tested on three optimization methods and compared to the standard non-synthesis optimization merit function. It was discovered that the performance of the new synthesis merit function depended heavily upon which of the three precision points were selected for use in the synthesis calculations. Subsequently, a method of pre-optimization selection of synthesis points was developed. It was found that when a favorable selection method was employed, the synthesis based merit function performed well, optimizing to a comparable merit function value in about 50 percent fewer function evaluations.
Errors in Constant-Velocity Shaft Couplings
Authors: Fischer Ian S. , Remington Philip M.
Published: March 2021

Shaft couplings with an odd number of joints are modeled with rotation matrices such that the transmission plane in which the axis of the central joint moves can be arbitrarily specified. It is shown that when the transmission plane coincides with the homokinetic plane, the mechanism functions as a constant velocity coupling, otherwise it does not. The cyclic variation in output speed, which occurs when the constant-velocity criteria is not met, is quantified and the results enable the design engineer to predict performance of constant-velocity couplings when deviation from ideal geometry occur because of manufacturing and installation tolerances or wear.
Obtaining the Minimal Set of Hybrid Parameter Differential Equations for Mechanisms
Authors: Barhorst Alan A. , Everett Louis J.
Published: March 2021

Mechanisms are inherently constrained devices. Combining flexibility with mechanisms usually requires using Lagrange multipliers to handle the constraints. The added algebraic or numerical tedium, associated with the Lagrange multipliers, is well documented. Presented in this paper is a technique for obtaining the minimal set of hybrid parameter differential equations for a constrained device. That is, the set of equations that inherently incorporate the constraints.

The technique illustrated in this paper is a recently developed hybrid parameter multiple body (HPMB) system modeling methodology. The variational nature of the methodology allows rigorous equation formulation providing not only the complete nonlinear, hybrid differential equations, but also the boundary conditions. The methodology is formulated in the constraint-free subspace of the system’s configuration space, thus Lagrange multipliers are not needed for constrained systems, regardless of the constraint type (holonomic or nonholonomic).

To evince the utility of the method, a flexible four bar mechanism is modeled. Particularly, the inversion of the slider crank found in the quick return mechanism. A comparison of Hamilton’s principle and the described technique, as they are applied to the mechanism, is included. It is shown that the same equations result from either method, but the new technique is much more concise, more efficiently handles the constraints, and requires less algebraic tedium.
An Experimental Study of Elastic Mechanism With Lumped Mass and Inertia Moment
Authors: Wang L. , Kovacevic R. , Zou Hui-jun
Published: March 2021

This study aims at the experimental investigation of the dynamic characterization of high-speed mechanism with great flexibility. We use the specific constraction mechanism TLJ as an example and focus our research on the influence of lumped mass and inertia moment. Using the auther’s KED analysis program KEDL, many important concepts have been put forward based on the results and some new conclusions have been drawn.
Rotatability Laws for Spherical N-Bar Chains
Authors: Kohli Dilip
Published: March 2021

A unique dimensional representation of a spherical linkage called the primary linkage is defined using supplemental transformations. This primary linkage representation has the property that the sum of its any two links is less than π. Then several theorems and lemmas concerning the assemblability, revolvability of angles and full rotatability are presented for this primary linkage representation using extensions of the spherical triangle inequalities.

Since all different supplemental dimensional representations of a spherical linkage are equivalent, the assemblability, revolvability of angles and the rotatability of links of an N-bar spherical linkage of a given dimensional representation can be determined by first determining the primary linkage representation and then using the theorems and laws provided in the paper. The rotatability criteria of spherical four-link and five-link mechanisms are very special cases of the N-bar rotatability criteria presented in the paper.
Indentification and Classification of Multi-Degree-of-Freedom and Multi-Loop Mechanisms
Authors: Liu Tyng , Yu Chung-Huang
Published: March 2021

This study concerns the degree-of-freedom, the arrangements of input and the type of mobility of multi-loop, multi-degree-of-freedom mechanisms. Firstly, “basic loops” is introduced, and a systematic scheme for identifying the actual degree-of-freedom of mechanisms is developed. The input, then, can be properly deployed, such that the mechanism has a totally constrained motion. Lastly, based on the input deployment, the mobility of mechanisms is classifed and identified into three types: total, partial and fractionated mobility. The procedure has been automated, and the atlas of all possible arrangements of input of up to eight-link planar mechanisms with only revolute joints is presented. The systematic method is helpful for the structural synthesis of multi-degree-of-freedom and multi-loop mechanisms, and for exploring their potential industrial applications.
The Design of Manipulator System With Pole Placement Approach
Authors: DeRong Wu
Published: March 2021

The manipulator system is a sequence of mechanisms jointed with each other. It is difficult to establish the dynamic state equation of such a mechanism system. By means of the bond graph method, it is easy to derive the state equation of a mechanism, then one have the transfer function matrix. According to the combined situation of mechanisms for manipulator, whose transfer function matrix may be obtained. Based on the modern control theory, one will find that in a controllable system, it is possible to place the poles anywhere we wish in the complex plane. In this paper one will develop a new procedure concerning system pole assignment within desired places by using two controllers. An example is illustrated.
An Automated Database System for Preliminary Spacecraft Design
Authors: Grooms H. R. , Blanchard W. , Hawthorne D. , Fisk K.
Published: March 2021

Spacecraft preliminary design is usually fast-paced and occasionally hectic. Decisions on configuration, propulsion systems, primary structure, cost, safety, reliability, and other disciplines are made almost daily. Keeping the design team informed of the decisions and the reasons for them in a timely fashion is a formidable task — one that is greatly facilitated by an automated database. This paper describes the scope, applications, and benefits of an automated base system that is currently in use on a spacecraft preliminary design project.
A Database Design Methodology for Fiber-Reinforced Composite Materials
Authors: Rasdorf William J. , Spainhour Lisa K. , Burns Bruce P.
Published: March 2021

Presently there is a great diversity of individuals and organizations involved in generating and using fiber-reinforced composite materials (FRCM) data. Because of this, many engineers and scientists are interested in creating a computing system to facilitate their access and use of such data. In order for such a system to be built, information needs to be compiled on the requirements of a database, one of the key elements of such a computing environment. This paper attempts to help analysts and designers understand and develop a fully integrated FRCM database by providing an overview of important database design considerations and elements. The first main section of this paper discusses 1) the application programs now being used for the fabrication, design, manufacture, and testing of FRCM components; 2) the data flow among these programs; 3) the need for a database management system to overcome existing system shortcomings; and 4) the advantages of selecting the relational data model to improve the present handling of data. The other main section of the paper provides a methodology for designing a database using the relational data model and describes the specific content and structure of this database that is proposed to be used in the FRCM computing environment.
Certified Athletic Trainers’ Use of Cervical Clinical Testing in the Diagnosis and Management of Sports-Related Concussion
Authors: Cheever Kelly , Kay Melissa
Published: March 2021

Context: Despite evidence implicating cervicogenic symptoms in the development of persistent postconcussion symptoms, factors that influence utilization of cervical clinical tests to identify cervicogenic symptoms following concussion are poorly understood. Objective: Explore barriers to the utilization of cervical clinical testing in multifaceted concussion evaluation. Design: Cross-sectional. Setting: Online survey. Patients or Other Participants: A total of 122 athletic trainers (AT) (age = 42.6 [6.4] y; female = 51.6%; 52% >10 y of clinical practice; 68% master’s degree or greater; 35% treated a minimum of 15 concussions/y). Main Outcome Measure(s): Perceived importance, clinical experience, number of concussions treated, utilization of cervical clinical tests following nonspecific cervical pathology and following concussion, comfort with cervical treatment modalities following a concussion, and recommendation for cervical-specific therapy to treat persistent postconcussion symptoms. Results: Ordinal logistic regression revealed perceived importance had the strongest positive impact on AT’s likelihood of high utilization of cervical clinical testing following concussion (95% CI, .17 to .99; P = .005), while clinical experience (95% CI, −.43 to .29; P = .71) and number of concussions treated/y (95% CI, −.21 to .31; P = .71) had no bearing. Moreover, low comfort with cervical treatments following a concussion (95% CI, −2.86 to −.26; P = .018) and low utilization of cervical clinical testing following nonspecific cervical pathology (95% CI, −7.01 to −3.39; P ≤ .001) had a strong positive impact on high utilization of cervical clinical testing following concussion. Two logistic regression models demonstrated how recommendations for cervical-specific therapy in persistent post-concussion symptom patients could be predicted based on (1) cervical test utilization and (2) perceptions and clinical experience with 79% and 78%, respectively. Conclusions: Perceived importance played a major role in utilization of cervical clinical test following concussion. ATs who utilized common cervical treatments when dealing with non-concussive injuries were more likely to utilize those same treatments to treat comorbid cervical pathology following a concussion.
Great Lakes people among first coppersmiths
Authors: Malakoff David
Published: March 2021

New dates show Native Americans worked pure ore nearly 10,000 years ago
Long live the queen
Authors: Law Yao-Hua
Published: March 2021

In insect societies, a queen can live for years, whereas workers expire in months. What can hives and anthills reveal about aging?
Scientific excellence and diversity at Annual Meeting
Authors: Korte Andrea
Published: March 2021

Showcasing diverse speakers requires a deliberate commitment to inclusion from decision-makers
WAVE2 suppresses mTOR activation to maintain T cell homeostasis and prevent autoimmunity
Authors: Liu Ming , Zhang Jinyi , Pinder Benjamin D. , Liu Qingquan , Wang Dingyan , Yao Hao , Gao Yubo , Toker Aras , Gao Jimin , Peterson Alan , Qu Jia , Siminovitch Katherine A.
Published: March 2021

WAVE-ing T cell activation off

The WAVE regulatory complex (WRC) is a pentameric complex that regulates actin cytoskeleton dynamics. The precise role for the WRC in immunity has not been established, although recent work has implicated WRC components such as HEM1 in certain human immunodeficiencies. Liu
et al.
characterized mice with a conditional knockout of the WRC constituent WAVE2 (see the Perspective by Hambleton). These mice exhibited progressive severe autoimmune and inflammatory disease associated with the activation and accelerated differentiation of T cells. WAVE2's suppression of T cell activation was not mediated by the T cell receptor but rather by its inhibition of mammalian target of rapamycin (mTOR) binding to RAPTOR and RICTOR. Accordingly, the autoimmune phenotype of these mice could be ameliorated by pharmacological inhibitors of mTOR signaling.

Science
, this issue p.
eaaz4544
; see also p.
1309
Liver type 1 innate lymphoid cells develop locally via an interferon-γ–dependent loop
Authors: Bai Lu , Vienne Margaux , Tang Ling , Kerdiles Yann , Etiennot Marion , Escalière Bertrand , Galluso Justine , Wei Haiming , Sun Rui , Vivier Eric , Peng Hui , Tian Zhigang
Published: March 2021

An IFN-γ feedback loop

Innate lymphoid cells (ILCs) play important roles in tissue homeostasis and host defense. Type 1 ILCs (ILC1s) produce interferon-γ (IFN-γ) and require the transcriptional master regulator T-bet. The pathways underlying how these cells develop and differentiate have remained poorly understood. Bai
et al.
found that the adult mouse liver contains a population of Lin–Sca-1
+
Mac-1
+
hematopoietic stem cells (LSM HSCs) that preferentially differentiate into tissue-resident liver ILC1s. They further show that IFN-γ produced by mature ILC1s promotes the expansion and differentiation of LSM HSCs into ILC1s but not natural killer cells. This work expands our understanding of extramedullary hematopoiesis and underscores the unique immune status of the liver.

Science
, this issue p.
eaba4177
Modulation of MHC-E transport by viral decoy ligands is required for RhCMV/SIV vaccine efficacy
Authors: Verweij Marieke C. , Hansen Scott G. , Iyer Ravi , John Nessy , Malouli Daniel , Morrow David , Scholz Isabel , Womack Jennie , Abdulhaqq Shaheed , Gilbride Roxanne M. , Hughes Colette M. , Ventura Abigail B. , Ford Julia C. , Selseth Andrea N. , Oswald Kelli , Shoemaker Rebecca , Berkemeier Brian , Bosche William J. , Hull Michael , Shao Jason , Sacha Jonah B. , Axthelm Michael K. , Edlefsen Paul T. , Lifson Jeffrey D. , Picker Louis J. , Früh Klaus
Published: March 2021

Viral peptide is key to T cell priming

Simian immunodeficiency virus (SIV) vaccines containing a strain 68-1 rhesus cytomegalovirus (RhCMV) vector elicit strong CD8
+
T cell responses that can control and clear SIV infections. The SIV peptides targeted by these T cells are presented on major histocompatibility complex (MHC) II and the nonclassical MHC-Ib molecule MHC-E rather than the more typical MHC-Ia. Verweij
et al.
show that the 68-1 RhCMV–encoded peptide VL9 drives intracellular transport of MHC-E and recognition of RhCMV-infected targets by MHC-E–restricted CD8
+
T cells. Rhesus macaques vaccinated with a mutant 68-1 RhCMV lacking VL9 showed no priming of MHC-E–restricted CD8
+
T cells and no protection against SIV. This work strongly suggests that future effective CMV-based HIV vaccines in humans will also require MHC-E–restricted CD8
+
T cell priming.

Science
, this issue p.
eabe9233
Stabilizing black-phase formamidinium perovskite formation at room temperature and high humidity
Authors: Hui Wei , Chao Lingfeng , Lu Hui , Xia Fei , Wei Qi , Su Zhenhuang , Niu Tingting , Tao Lei , Du Bin , Li Deli , Wang Yue , Dong He , Zuo Shouwei , Li Bixin , Shi Wei , Ran Xueqin , Li Ping , Zhang Hui , Wu Zhongbin , Ran Chenxin , Song Lin , Xing Guichuan , Gao Xingyu , Zhang Jing , Xia Yingdong , Chen Yonghua , Huang Wei
Published: March 2021

Perovskite synthesis out in the open

Although methods have been developed that create the photoactive black perovskite phase of formamidinium lead iodide (α-FAPbI
3
), these routes are temperature and humidity sensitive and less compatible with large-scale solar cell production. Hui
et al.
report an alternative route in which vertically aligned lead iodide thin films are grown from the ionic liquid methylamine formate. Nanoscale channels in the films lower the barrier to permeation of formamidinium iodide and enable transformation to α-FAPbI
3
, even at high humidity and room temperature. Solar cells made with these films have power conversion efficiencies as high as 24.1% that display high stability.

Science
, this issue p.
1359
Raising standards to lower diesel emissions
Authors: Schwarzman Megan , Schildroth Samantha , Bhetraratana May , Alvarado Álvaro , Balmes John
Published: March 2021

California policies protect vulnerable communities the most and should be adopted nationwide
MAGI-1 PDZ2 Domain Blockade Averts Adenovirus Infection via Enhanced Proteolysis of the Apical Coxsackievirus and Adenovirus Receptor
Authors: Alghamri Mahmoud S. , Sharma Priyanka , Williamson Timothy L. , Readler James M. , Yan Ran , Rider S. Dean , Hostetler Heather A. , Cool David R. , Kolawole Abimbola O. , Excoffon Katherine J. D. A.
Published: March 2021

Adenovirus is a common threat in immunosuppressed populations and military recruits. There are no currently approved treatments/prophylactic agents that protect from most AdV infections.
Persistence of Ambigrammatic Narnaviruses Requires Translation of the Reverse Open Reading Frame
Authors: Retallack Hanna , Popova Katerina D. , Laurie Matthew T. , Sunshine Sara , DeRisi Joseph L.
Published: March 2021

Fundamental to our understanding of RNA viruses is a description of which strand(s) of RNA are transmitted as the viral genome relative to which encode the viral proteins. Ambigrammatic narnaviruses break the mold.
Latest Quaternary slip rates of the San Bernardino strand of the San Andreas fault, southern California, from Cajon Creek to Badger Canyon
Authors: McGill S.F. , al. et
Published: March 2021

Additional details on methods and for descriptions and interpretations of geologic units at the Badger Canyon site. Additional trench logs and photographs showing locations of dated samples that were not shown in other figures. Tables providing latitude and longitude for all dated samples, as well as field and lab data for terrestrial nuclide dating and complete soil descriptions.
Association of spontaneous abortion with all cause and cause specific premature mortality: prospective cohort study
Authors: Wang Yi-Xin , Mínguez-Alarcón Lidia , Gaskins Audrey J , Missmer Stacey A , Rich-Edwards Janet W , Manson JoAnn E , Pan An , Chavarro Jorge E
Published: March 2021

Objective

To investigate the association of spontaneous abortion with the risk of all cause and cause specific premature mortality (death before the age of 70).

Design

Prospective cohort study.

Setting

The Nurses’ Health Study II (1993-2017), United States.

Participants

101 681 ever gravid female nurses participating in the Nurses’ Health Study II.

Main outcomes measures

Lifetime occurrence of spontaneous abortion in pregnancies lasting less than 6 months, determined by biennial questionnaires. Hazard ratios and 95% confidence intervals for all cause and cause specific premature death according to the occurrence of spontaneous abortion, estimated with time dependent Cox proportional hazards models.

Results

During 24 years of follow-up, 2936 premature deaths were recorded, including 1346 deaths from cancer and 269 from cardiovascular disease. Crude all cause mortality rates were comparable for women with and without a history of spontaneous abortion (1.24 per 1000 person years in both groups) but were higher for women experiencing three or more spontaneous abortions (1.47 per 1000 person years) and for women reporting their first spontaneous abortion before the age of 24 (1.69 per 1000 person years). The corresponding age adjusted hazard ratios for all cause premature death during follow-up were 1.02 (95% confidence interval 0.94 to 1.11), 1.39 (1.03 to 1.86), and 1.27 (1.11 to 1.46), respectively. After adjusting for confounding factors and updated dietary and lifestyle factors, the occurrence of spontaneous abortion was associated with a hazard ratio of 1.19 (95% confidence interval 1.08 to 1.30) for premature mortality during follow-up. The association was stronger for recurrent spontaneous abortions (hazard ratio 1.59, 95% confidence interval 1.17 to 2.15 for three or more spontaneous abortions; 1.23, 1.00 to 1.50 for two; and 1.16, 1.05 to 1.28 for one compared with none), and for spontaneous abortions occurring early in a woman’s reproductive life (1.32, 1.14 to 1.53 for age ≤23; 1.16, 1.01 to 1.33 for ages 24-29; and 1.12, 0.98 to 1.28 for age ≥30 compared with none). When cause specific mortality was evaluated, the association of spontaneous abortion with premature death was strongest for deaths from cardiovascular disease (1.48, 1.09 to 1.99). Spontaneous abortion was not related to premature death from cancer (1.08, 0.94 to 1.24).

Conclusions

Spontaneous abortion was associated with an increased risk of premature mortality, particularly death from cardiovascular disease.
Quality of rheumatology care for patients with fibromyalgia and chronic pain syndromes
Authors: Pang Hilary YM , Farrer Chandra , Wu Wei , Gakhal Natasha K
Published: March 2021

Background

One-third of primary care providers (PCPs) refer patients with fibromyalgia or chronic pain (FM/CP) to specialist care, typically rheumatology. Yet, comprehensive data on the quality of rheumatology care for patients with FM/CP are currently lacking.

Methods

Records of patients referred for rheumatology consultation for FM/CP and seen at a single academic centre between 2017 and 2018 were extracted by retrospective chart review. Variables were diagnostic accuracy (at referral vs consultation), resource utilisation (investigations, medications, medical and allied health referral), direct costs (physician billing, staff salary, investigation fees) and access (consult wait time). Patient experience and referring PCP experience surveys were administered.

Results

79 charts were identified. Following consultation, 81% of patients (n=64) maintained the same diagnosis of FM/CP, 19% (n=15) were diagnosed with regional pain and 0% of patients (n=0) were diagnosed with an inflammatory arthritis or connective tissue disease. Investigations were ordered for 37% of patients (n=29), medication prescribed for 10% (n=8) and an allied health referral provided for 54% (n=43). Direct costs totalled $19 745 (average $250/consult; range $157–$968/consult). Consultation wait time averaged 184 days (range 62–228 days). Out of the seven (64%) responses to the patient experience survey, 86% of patients (n=6) were satisfied with provider communication but the consultation ‘definitely’ met the expectations of only 57% (n=4). The PCP survey returned an insufficient response rate.

Conclusions

This study found that no patient referred to rheumatology care for FM/CP was diagnosed with an inflammatory arthritis or connective tissue disease. Furthermore, patients with FM/CP experience lengthy wait times for rheumatology care which delay their management of chronic pain. Interdisciplinary and collaborative healthcare models can potentially provide higher quality care for patients with FM/CP.
Let’s do better: public representations of COVID-19 science
Authors: Caulfield Timothy , Bubela Tania , Kimmelman Jonathan , Ravitsky Vardit
Published: March 2021

COVID science is being both done and circulated at a furious pace. While it is inspiring to see the research community responding so vigorously to the pandemic crisis, all this activity has also created a churning sea of bad data, conflicting results, and exaggerated headlines. With representations of science becoming increasingly polarized, twisted, and hyped, there is growing concern that the relevant science is being represented to the public in a manner that may cause confusion, inappropriate expectations, and the erosion of public trust. Here we explore some of the key issues associated with the representations of science in the context of the COVID-19 pandemic. Many of these issues are not new. But the COVID-19 pandemic has placed a spotlight on the biomedical research process and amplified the adverse ramifications of poor public communication. We need to do better. As such, we conclude with 10 recommendations aimed at key actors involved in the communication of COVID-19 science, including government, funders, universities, publishers, media, and the research communities.
Refinements of the bottom and strange MSSM Higgs Yukawa couplings at NNLO
Authors: Ghezzi Margherita , Glaus Seraina , Müller Dario , Schmidt Timo , Spira Michael
Published: March 2021

We extend the already existing two-loop calculation of the effective bottom-Yukawa coupling in the MSSM. In addition to the resummation of the dominant corrections for large values of tg$$\beta $$β, we include the subleading terms related to the trilinear Higgs coupling$$A_b$$Aband contributions induced by the electroweak gauge couplings. This calculation has been extended to the NNLO corrections to the MSSM strange-Yukawa coupling. Our analysis leads to residual theoretical uncertainties of the effective Yukawa couplings at the per-cent level.
Breaking reciprocity and preserving-frequency using linear acoustic metamaterials
Authors: Li Hongzhu , Ding Qian , Ma Zhisai , Ren Qingquan , Lyu Xiaofei , Qin Zhao-Hong , Wei Long , Kamil Żur Krzysztof , Yang Tianzhi
Published: March 2021

In this paper, we introduce a linear waveguide implemented by cascading acoustic black holes (ABHs). The asymmetric wave propagation, up to 46 dB, is observed and verified in simulation and experiment. It is shown that, in comparison with the previous nonlinear acoustic diodes, our waveguide can rectify the sound without shifting the impinging sound frequency. The device is simple and easy-to-fabricate without using complex nonlinear materials and space–time modulation. This feature could open a new route for designing acoustic waveguide devices that preserve the key information.
Numerical soliton solutions of fractional (2 + 1)-dimensional Nizhnik–Novikov–Veselov equations in nonlinear optics
Authors: Sagar B , Saha Ray S.
Published: March 2021

In this paper, time-fractional (2 + 1)-dimensional Nizhnik–Novikov–Veselov equations have been solved numerically utilizing the Kansa method, in which the multiquadrics are taken as radial basis function. To attain this, a numerical scheme based on finite difference and Kansa method has been proposed. In addition, the soliton solutions have been obtained by employing Kudryashov method and tanh method for comparison purpose with the obtained numerical solutions. The numerical examples are given to demonstrate the accuracy and applicability of the proposed method.
Effect of hybridization parity on multiband superconductors properties
Authors: Ramos W. M. P. , Padilha I. T.
Published: March 2021

We investigated the influence that hybridization parity has on the so-called multiband superconductors, where we proposed a model with two bands [Formula: see text] and [Formula: see text]. Thus, we observe the behavior of intra-band superconductivity, the one whose coupling occurs between carriers that belong to the same band [Formula: see text] or [Formula: see text], and inter-bands, when the coupling occurs between carriers of different bands [Formula: see text] with [Formula: see text] — from graphs of the order parameter as a function of hybridization and the order parameter as a function of temperature, for null temperature in the first case and for finite temperature in the second, as well as intraband phase diagrams. In this sense, the study of the influence that hybridization has on superconductivity is fundamental for understanding unconventional superconductors, such as heavy fermions and high-temperature superconductors.
IMPROVEMENT OF SURFACE POTENTIAL ENERGY OF INDIUM TIN OXIDE THIN FILM MODIFIED WITH ORGANIC SEMICONDUCTOR MATERIAL BASED ON PHENYL GROUP
Authors: HAVARE ALI KEMAL
Published: March 2021

This study focuses on surface characterization of modified indium tin oxide (ITO) for potential applications as anode in organic electronics devices. [4-iodophenyl]-silanetriol molecules were coated by self-assembled monolayers method on ITO surface. Kelvin Probe Microscopy, Scanning Tunneling Microcopy and X-ray Photoelectron Spectroscopy techniques were used to analyze the modified ITO surface. The results show that organic semiconductor material based on Phenyl group enhance surface morphology and increase the surface potential energy of ITO around [Formula: see text][Formula: see text]meV and contribute the tunneling current that inject from Fermi energy level of the ITO. This study includes the influence of surface interactions on electrochemical and spectral features of compounds. The results are important in developing surface structures in amorphous layers, better understanding the mechanism of creation of such structures on ITO surface.