bluuebunny/crossref_metadata_2025 huggingface dataset:
Standing trans‐nasal endoscopic guided CO2 laser fenestration of the palatine bone to access the sphenopalatine sinus in a horse
Authors: Perez Jairo A. , Hutton Anne E. , Cudd Sarah K. , Brown James A.
Published: April 2021

Objective

To describe a novel standing trans‐nasal endoscopic guided CO2 laser fenestration approach to access the sphenopalatine sinus (SPS) in the horse.

Study design

Case report.

Animals

Cadaver study and client‐owned 20‐year‐old Warmblood gelding.

Methods

The rostral palatine bone within the nasopharynx was investigated as a possible site for fenestration to access the SPS in cadavers. The ability to fenestrate the SPS was tested in cadavers using a flexible endoscope and CO2 laser fiber inserted via biopsy channel. The fenestration procedure was then performed in a clinical case presented for unilateral epistaxis where a soft tissue attenuating mass in the right SPS was identified with standing computed tomography (CT).

Results

The cadaver study demonstrated the appropriate site within the nasopharynx midway between the vomer and dorsal conchal wall. The CO2 laser successfully ablated the mucosa and palatine bone to enable endoscopic access to the palatine portion of the SPS. The endoscopic procedure was performed as a two‐step process via standing sedation due to mucosal bleeding obscuring visualization. Access to the SPS through fenestration allowed biopsy under direct endoscopic visualization with long‐handled bronchoesophageal forceps inserted via the ipsilateral middle meatus. The mass within SPS was determined to be an undifferentiated carcinoma. Further treatment was declined and the horse euthanized 6 months following the procedure due to acute onset of neurologic symptoms.

Conclusion

Endoscopically guided fenestration of the rostral palatine bone within the nasopharynx using CO2 laser in the standing horse provided good access and visualization of the palatine portion of the SPS.
Singular units and isogenies between CM elliptic curves
Authors: Li Yingkun
Published: April 2021

In this note, we will apply the results of Gross–Zagier, Gross–Kohnen–Zagier and their generalizations to give a short proof that the differences of singular moduli are not units. As a consequence, we obtain a result on isogenies between reductions of CM elliptic curves.
Computer Aided Rheological Design of Injection Molded Products
Authors: Zeid I.
Published: April 2021

Traditionally, injection mold design has been quite empirical, relying on previous experiences, rather than sound engineering principles. This is due to the lack of algorithms available to injection mold designers. With the continuous advancement of the CAD/CAM technology, new principles can be developed to generate fully integrated and automated mold design procedures. This paper presents a methodology of a more analytical approach to mold design. Such methodology is based on the branching technique which is utilized to develop the required data for the rheological analysis. A post-processor is also developed to enable mold designers make their decisions. Numerical experiments are included to demonstrate the scope of the analytical approach.
A Fuzzy Sets Approach to Computational Tools for Preliminary Engineering Design
Authors: Wood K. L. , Antonsson E. K.
Published: April 2021

The primary goal of this research is to provide computational tools, or aids, to engineering designers, particularly for the preliminary phase of design. Such aids will be particularly useful in choosing between alternative technologies. Design choices of this nature are perhaps the most critical, and likely to be the most costly if in error. Our approach has been to aid preliminary design decisions with analysis tools developed for computations on imprecise parameters. Contemporary computers and algorithms are not well suited for manipulating imprecise descriptions of objects. To provide these basic tools, we are applying the mathematics of fuzzy sets. This approach (along with “data-driven programming”) appears to be well suited to our problem and has been applied to similar problems in analyzing civil engineering structures and failures.
Fault Tree Approach for the Reliability Analysis of Gear Trains: Part I — Basic Theory
Authors: Pan T. S. , Rao S. S.
Published: April 2021

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.
Position-Sensor-Driven Assembly
Authors: Gordon S. T. , Seering W. P.
Published: April 2021

A sensor based assembly technique is described which uses a part position sensor to locate certain part features prior to a mating operation. The rigid parts assembly process is divided into three phases: part acquisition, alignment and mating. The part position sensor is used to increase the accuracy of the part alignment phase and decrease the system compliance requirements for the mating phase. The system is shown to be relatively insensitive to robot kinematic errors. A prototype system is described which assembles a number of closely fitting parts.
An Expert System for Initial Selection of Dwell Linkages
Authors: Kota S. , Erdman A. G. , Riley D. R. , Esterline A. , Slagle J. R.
Published: April 2021

Dwell linkages have numerous applications in industry, especially in automation. Traditional use of more expensive cams is due to lack of proper design tools for synthesizing dwell linkages. By systematically and extensively studying entire motion characteristics of hundreds of linkages, a comprehensive classification system and heuristics were developed. This qualitative classification scheme led to a finite set of linkage models that cover the entire design space in the sense that any possible design falls under one or more of the models. Our system, called Dwell-Expert, incorporates design expertise to select the best linkage model for a given set of design specifications and to compare that model against alternatives. This new design methodology and its implementation in AGNESS (A Generalized Network-based Expert System Shell) are explained. A design example is presented. Our system can reduce even an experienced designer’s initial-design time from a day or more to a minute or less, assuming specifications have already been formulated. Such results motivate extension of this design methodology to other areas of mechanical design and engineering design in general.
A Hybrid-Type Expert System for the Design of Marine Power Plants Using AI Technique and Design Optimization Method
Authors: Akagi S. , Tanaka T. , Kubonishi H.
Published: April 2021

A hybrid-type expert system is developed for supporting the initial design process of marine power plants. Firstly, discussion is given generally to understand design process in the view point of applying the AI technique effectively to design. Based on the result of the discussion, a hybrid-type expert CAD system with coupling the AI technique and the numerical optimization method is developed. In the system, the design knowledge is represented in the production rules, and the data of machineries consisting the plant are described by the frame-type representation. Through the system execution, it is ascertained that the system is effective not only as the design tool assisting designers but also as the tool instructing inexperienced designers.
Shape Optimum Design of Robotic Manipulators With Static Performance Criteria
Authors: Saravanos D. A. , Lamancusa J. S. , Sommer H. J.
Published: April 2021

The end effector deflections of robotic manipulators may be minimized by optimizing the geometric shape and the dimensions of their links. A multiple posture static performance criterion for the prediction of the shape optimum design is presented. An efficient optimization algorithm is developed for the solution of the problem using finite element modeling to predict the compliance of the robotic arm. The method is applied to an existing robotic arm, and the results demonstrate that simple alterations to the dimensions and the shape of the links can greatly improve, not only the stiffness, but also the stiffness/mass ratio and consequently the vibrational response of the manipulator structure.
Characteristic Surfaces for Three Position Function Generation With Planar Four Bar Mechanisms
Authors: Barker C. R. , Tso P.-L.
Published: April 2021

This paper considers the relationship between the three position function generation problem and the solution space for planar four bar mechanisms. The two infinities of solutions possible are mapped in a plane to determine the locations where particular types of mechanisms occur. It is possible to generate a contour in the mapping plane which joins together all solutions which possess a common characteristic in regard to their link lengths. This same contour can be displayed in the solution space to ascertain the overall characteristics of potential solutions to the design problem. A numerical example is used for illustrative purposes, but the results can be applied to any three position function generation problem.
Synthesis and Balancing of Cam-Modulated Linkages
Authors: Pracht P. , Minotti P. , Dahan M.
Published: April 2021

Linkages are inherently light, inexpensive, strong, adaptable to high speeds and have little friction. Moreover the class of functions suitable for linkage representation is large. For all these reasons numerous recent works deal with the problem of design mechanisms for robotic applications, but very often in terms of components such as gripper, transmission, balancing.

We investigate a new application for linkages, using them to design industrial manipulator. The selected mechanism for this application is a four bar linkage with an adjustable lengh for exact path generation. This adjustment is performed by a track or cam which is substituted to a bar. By this mean, we define a cam-modulated linkage which possess superior accuracy potential and is capable of accomodating of industrial design restrictions.

Such a kinematic chain is free from structural error for path generation and the presence of the track introduces the flexibility and versality in the usefull four bar chain. The synthesis technique of cam modulated linkage utilizes loop closure equations, envelop theory to find the centerline and the profile of the track. These techniques provide a systematic approach to the design of mechanism for path generation when extreme accuracy is required.

In order to complete an contribution, we take in consideration the static balancing of the synthesized manipulator. To achieve static mass balancing we use the potential energy storage capabilities of linear springs, and integrated it with the non-linear motion of mechanism to provide an exact value of the desired counter loading functions.

Examples are worked to demonstrate applications of these procedures and to illustrate the industrial potential of spring balancing and cam-modulated linkage.
Singularities in Motion and Displacement Functions for RCRCR, RCRRC and RSRC Linkages: Part III — RCRRC Linkage
Authors: Litvin F. L. , Fanghella P.
Published: April 2021

The general approach for the determination of singularities in motion and displacement functions for spatial linkages has been developed by Litvin, et al. (1986b) and also represented in the first part of this paper. Applications of the developed methods for the RCRRC linkage are given in this paper. The authors determined the singularities in motion, displacement functions and the configurations of the linkage. Numerical examples are given.
Simulation of Planar Dynamic Mechanical Systems With Changing Topologies: Part II — Implementation Strategy and Simulation Results for Example Dynamic Systems
Authors: Gilmore B. J. , Cipra R. J.
Published: April 2021

Part II presents a technique which uses the general point to line kinematic constraint equation presented in Part I coupled with an incidence matrix to automatically formulate the kinematic constraint equations between contacting rigid bodies and solve the resulting dynamic equations of motion. The automatic determination of system connectivity coupled with impulse-momentum theory enables the strategy to handle impact between rigid bodies in line contact or between rigid bodies in topologically complex systems. The characterizations of the changes in the kinematic constraints, as described by Part I, are combined with the incidence matrix and impact analysis to form an automatic dynamic simulation strategy. The strategy automatically predicts, detects, and determines the changes in the system topology and then reformulates the equations of motion without the user specifying the kinematic constraint changes and resulting system topology. The simulation results of two example systems are presented. The examples illustrate the effect the boundaries have on a system’s motion and show that the only connectivity data required by the strategy is the initial system topology.
An Experimental Investigation of the Static and Elastodynamic Responses of an Industrial Robotic Manipulator
Authors: Choi S. B. , Sun F. , Gandhi M. V. , Thompson B. S.
Published: April 2021

A methodology is presented herein for experimentally evaluating the static and elastodynamic responses of industrial robotic manipulators. The procedure enables estimates of the principal characteristics of these machines to be quantified in order to identify limitations in the structural elements of these designs. Furthermore, the proposed approach also provides experimental data with which to evaluate the predictive capabilities of the various mathematical models proposed in the literature for predicting the static and elastodynamic behavior of these systems. In order to demonstrate the test procedure, a General Electric Company P50 articulating robot was subjected to evaluation, the error sources identified and the associated errors quantified.
A Constrained Search Technique for Motion Generator Pivot Location
Authors: Lawley T. J. , Nambiar R. V. , Nisbett J. K. , Prince S. , Zarefar H.
Published: April 2021

Burmester’s solution to the problem of guiding a body through four precision points has been extended to find planar mechanisms that have their pivots located inside prescribed regions. The complex number formulation has been used to generate the Burmester curves. A random search technique was developed to choose a new set of precision points that lie within user specified limits, in order to find a set of curves that pass through the desired regions. A computer program was written to generate Burmester curves that lie within the desired regions, while maintaining a coupler motion within satisfactory limits. An automobile suspension linkage was successfully designed using this program.
Synthesis of Harmonic Motion Generating Linkages: Part I — Function Generation
Authors: Farhang K. , Midha A. , Bajaj A. K.
Published: April 2021

This paper deals with the first- and higher-order function generation problems in the synthesis of linkages with relatively small input cranks. Such linkages tend to produce nearly simple harmonic motions at the output members. Owing to this distinction, the generality of the conventional synthesis techniques is no longer applicable. Thus, in function generation, only harmonic functions of the input motion may be expected to be synthesized for output motions.
Synthesis of Harmonic Motion Generating Linkages: Part II — Path and Motion Generation
Authors: Farhang K. , Midha A. , Hall A. S.
Published: April 2021

This paper, a sequel to a companion paper on function generation, discusses the path and motion generation problems in the synthesis of linages with relatively small input cranks. The point on the floating link (i.e., the coupler of a crank-rocker linkage point on connecting rod in a slider-crank linkage) traces an approximate ellipse. This fact serves as a major distinction between the method described herein and the conventional, more general, synthesis techniques. In other words, only elliptical paths may be generated by the path (or coupler) points in the synthesis of linkages with small cranks. Higher order path and motion generation, in which velocity, acceleration, slope and the rate of change of slope of the coupler path may be specified, are also addressed in this paper.
The Evaluation of Moments of Bounded Regions Using Spline Approximations of the Boundary
Authors: Angeles J. , Chaoming Z. , Duarte R. , Ning H.
Published: April 2021

The subject of this paper is the computation of the first three moments of bounded regions imbedded in 2- and 3-dimensional Euclidean spaces. The method adopted here is based upon formulae derived elsewhere, that permit the computation of the said moments — volume, vector first moment and inertia tensor — via integration along the boundary. This is accomplished by the application of Gauss Divergence Theorem to planar and axially-symmetric 3-D regions. It is shown that a spline approximation of the boundary leads to explicit, readily implementable formulae. Two examples are included to illustrate the applicability of the procedure.
A New Dynamic Basis Algorithm for Solving Linear Programming Problems for Engineering Design
Authors: Wang Y. , Sandgren E.
Published: April 2021

A new linear programming algorithm is proposed which has significant advantages compared to the traditional simplex method. The search direction generated which is always along a common edge of the active constraint set, is used to locate candidate constraints, and can be used to modify the current basis. The dimension of the basis begins at one and dynamically increases but remains less than or equal to the number of design variables. This is true regardless of the number of inequality constraints present including upper and lower bounds. The proposed method can operate equally well from a feasible or infeasible point. The pivot operation and artificial variable strategy of the simplex method are not used. Examples are presented and results are compared with a traditional revised simplex method.
A Modification of Feasible Direction Optimization Method for Handling Equality Constraints
Authors: Chen Yong , Li Bailin
Published: April 2021

The Feasible Direction Method of Zoutendijk has proven to be one of the efficient algorithm currently available for solving nonlinear programming problems with only inequality type constraints. Since in the case of having equality type constraints, there does not exist nonzero direction close to the feasible region, the traditional algorithm can not work properly. In this paper, a modified feasible direction finding technique has been proposed in order to handle nonlinear equality constraints for the Feasible Direction Method. The algorithm is based on searching along directions intersecting the tangent of the equality constraints at some angle which makes the move toward the interior of the feasible region.
On the Design of Wire Rope
Authors: Velinsky S. A.
Published: April 2021

In recent work, Velinsky (1988) has developed a design methodology for multi-lay wire strands. The current paper expands on this work to study wire ropes in which the strand is a basic component. Wire ropes with the three types of cores, independent-wire-rope-core (IWRC), fiber-core (FC), and wire-strand-core (WSC), are considered. This work further generalizes the previously developed linearized theory which, through substantiation with experiment, is felt to be reasonably accurate for most wire rope behavior. The theory is then utilized to examine various parameters in the design of wire ropes.
Workspace Analysis of Multibody Mechanical Systems Using Continuation Methods
Authors: Jo D.-Y. , Haug E. J.
Published: April 2021

A new approach to numerical analysis of workspaces of multibody mechanical systems is developed. Numerical techniques that are based on manifold theory and utilize continuation methods are presented and applied to a variety of mechanical systems, including closed-loop mechanisms. Generalized coordinates that define kinematics of a system are classified and interpreted from an input-output point of view. Boundaries of workspaces, which depend on the classification of generalized coordinates, are defined as sets of singular points of Jacobians of the kinematic equations. Numerical methods for tracing one dimensional trajectories on a workspace boundary are outlined and example are analyzed using one dimensional manifold mapping computer programs, such as PITCON and AUTO.
A Network Implementation of Real-Time Dynamic Simulation With Interactive Animated Graphics
Authors: Dubetz M. W. , Kuhl J. G. , Haug E. J.
Published: April 2021

This paper presents a network based implementation of real-time dynamic simulation methods. An interactive animated graphics environment is presented that permits the engineer to view high quality animated graphics rendering of dynamic performance, to interact with the simulation, and to study the effects of design variations, while the simulation is being carried out. An industry standard network computing system is employed to interface the parallel processor that carries out the dynamic simulation and a high speed graphics processor that creates and displays animated graphics. Multi-windowing and graphics processing methods that are employed to provide visualization and operator control of the simulation are presented. A vehicle dynamics application is used to illustrate the methods developed and to analyze communication bandwidth requirements for implementation with a compute server that is remote from the graphics workstation. It is shown that, while massive data sets are generated on the parallel processor during realtime dynamic simulation and extensive graphics data are generated on the workstation during rendering and display, data communication requirements between the compute server and the workstation are well within the capability of existing networks.
Motion Analysis of a Driving Simulator With Nine Degrees-of-Freedom
Authors: Gutman Y. , Filshtinsky M.
Published: April 2021

Computer simulations provide means, not otherwise possible, for engineers to inspect in detail all actions and interactions between parts and subsystems for optimization of performance of the total system [10, 12].
A Vehicle Handling Model With Active Suspensions
Authors: Shannan J. E. , Vanderploeg M. J.
Published: April 2021

This paper presents two different vehicle models used to investigate the effects of active suspensions. One is a linear seven degree of freedom ride model. The second is a nonlinear ten degree of freedom ride and handling model. Full state feedback optimal control algorithms are developed for both models. The seven degree of freedom model is used to study ride effects. The active suspension substantially reduced the motions of the sprung mass. The ten degree of freedom model is used to study the effects of the active suspension on the directional response characteristics of the vehicle. The handling characteristics exhibited by the active suspension are very similar to those of the passive suspension. However, the active suspension did significantly reduce sprung mass motions during the handling maneuvers. It is then illustrated that by altering various feedback gains, active suspensions can be made to change the handling characteristics in the nonlinear range.
Consonantal F0 perturbation in American English involves multiple mechanisms
Authors: Xu Yi , Xu Anqi
Published: April 2021

In this study, we revisit consonantal perturbation of F0 in English, taking into particular consideration the effect of alignment of F0 contours to segments and the F0 extraction method in the acoustic analysis. We recorded words differing in consonant voicing, manner of articulation, and position in syllable, spoken by native speakers of American English in both statements and questions. In the analysis, we compared methods of F0 alignment and found that the highest F0 consistency occurred when F0 contours were time-normalized to the entire syllable. Applying this method, along with using syllables with nasal consonants as the baseline and a fine-detailed F0 extraction procedure, we identified three distinct consonantal effects: a large but brief (10–40 ms) F0 raising at voice onset regardless of consonant voicing, a smaller but longer-lasting F0 raising effect by voiceless consonants throughout a large proportion of the following vowels, and a small lowering effect of around 6 Hz by voiced consonants, which was not found in previous studies. Additionally, a brief anticipatory effect was observed before a coda consonant. These effects are imposed on a continuously changing F0 curve that is either rising-falling or falling-rising, depending on whether the carrier sentence is a statement or a question.
Stepwise pathogenic evolution of
Mycobacterium abscessus
Authors: Bryant Josephine M. , Brown Karen P. , Burbaud Sophie , Everall Isobel , Belardinelli Juan M. , Rodriguez-Rincon Daniela , Grogono Dorothy M. , Peterson Chelsea M. , Verma Deepshikha , Evans Ieuan E. , Ruis Christopher , Weimann Aaron , Arora Divya , Malhotra Sony , Bannerman Bridget , Passemar Charlotte , Templeton Kerra , MacGregor Gordon , Jiwa Kasim , Fisher Andrew J. , Blundell Tom L. , Ordway Diane J. , Jackson Mary , Parkhill Julian , Floto R. Andres
Published: April 2021

Jump starting pathogen evolution

Mycobacteria are mostly environmental saprotrophs, but during human history, some have become our pathogens. In the past 50 years or so, intractable and virulent infections of
Mycobacterium abscessus
have emerged in people with cystic fibrosis. Bryant
et al.
investigated how these mycobacteria have evolved into human pathogens so quickly (see the Perspective by Brugha and Spencer). Chronic infections in the lung offer plenty of evolutionary scope for the emergence of virulent clones after horizontal gene transfer and hypermutation. Pathogens are acquired by environmental contamination, which leaves open a window for clinical control because the most virulent clones survive poorly outside the body. Therefore, immediate treatment and enhanced infection-control measures for
M. abscessus
cases could reduce opportunities for the evolution of direct person-to-person transmission.

Science
, this issue p.
eabb8699
; see also p.
465
Going with the grains
Authors: Fatemi Valla , Devoret Michel H.
Published: April 2021

Coherent interfaces may not be vital for combining semi- and superconducting materials
A widespread pathway for substitution of adenine by diaminopurine in phage genomes
Authors: Zhou Yan , Xu Xuexia , Wei Yifeng , Cheng Yu , Guo Yu , Khudyakov Ivan , Liu Fuli , He Ping , Song Zhangyue , Li Zhi , Gao Yan , Ang Ee Lui , Zhao Huimin , Zhang Yan , Zhao Suwen
Published: April 2021

Biosynthesis and replication, from A to Z

Four nucleobases. adenine (A), cytosine (C), guanine (G), and thymine (T), are usually thought to be invariable in DNA. In bacterial viruses, however, each of the DNA bases have variations that help them to escape degradation by bacterial restriction enzymes. In the genome of cyanophage S-2L, A is completely replaced by diaminopurine (Z), which forms three hydrogen bonds with T and thus creates non–Watson-Crick base pairing in the DNA of this virus (see the Perspective by Grome and Isaacs). Zhou
et al.
and Sleiman
et al.
determined the biochemical pathway that produces Z, which revealed more Z genomes in viruses hosted in bacteria distributed widely in the environment and phylogeny. Pezo
et al.
identified a DNA polymerase that incorporates Z into DNA while rejecting A. These findings enrich our understanding of biodiversity and expand the genetic palette for synthetic biology.

Science
, this issue p.
512
,
516
,
520
; see also p.
460
Noncanonical DNA polymerization by aminoadenine-based siphoviruses
Authors: Pezo Valerie , Jaziri Faten , Bourguignon Pierre-Yves , Louis Dominique , Jacobs-Sera Deborah , Rozenski Jef , Pochet Sylvie , Herdewijn Piet , Hatfull Graham F. , Kaminski Pierre-Alexandre , Marliere Philippe
Published: April 2021

Biosynthesis and replication, from A to Z

Four nucleobases. adenine (A), cytosine (C), guanine (G), and thymine (T), are usually thought to be invariable in DNA. In bacterial viruses, however, each of the DNA bases have variations that help them to escape degradation by bacterial restriction enzymes. In the genome of cyanophage S-2L, A is completely replaced by diaminopurine (Z), which forms three hydrogen bonds with T and thus creates non–Watson-Crick base pairing in the DNA of this virus (see the Perspective by Grome and Isaacs). Zhou
et al.
and Sleiman
et al.
determined the biochemical pathway that produces Z, which revealed more Z genomes in viruses hosted in bacteria distributed widely in the environment and phylogeny. Pezo
et al.
identified a DNA polymerase that incorporates Z into DNA while rejecting A. These findings enrich our understanding of biodiversity and expand the genetic palette for synthetic biology.

Science
, this issue p.
512
,
516
,
520
; see also p.
460
Gut microbiota through an evolutionary lens
Authors: Carmody Rachel N. , Sarkar Amar , Reese Aspen T.
Published: April 2021

Reversing some industrialization-related changes in the human gut microbiota may be risky
Widespread reforestation before European influence on Amazonia
Authors: Bush M. B. , Nascimento M. N. , Åkesson C. M. , Cárdenes-Sandí G. M. , Maezumi S. Y. , Behling H. , Correa-Metrio A. , Church W. , Huisman S. N. , Kelly T. , Mayle F. E. , McMichael C. N. H.
Published: April 2021

Pre-Columbian reforestation in Amazonia

An early 17th-century temporary reduction in global atmospheric carbon dioxide (CO
2
) levels was previously attributed to reforestation in Amazonia after the catastrophic loss of life of the indigenous population caused by diseases brought by European invaders. Using fossil pollen data from Amazonian lake sediments with temporal resolution over the past millennium, Bush
et al.
found that forest recovery began 300 to 600 years before the population crash. The more recent nadir in atmospheric CO
2
was not associated with rapid reforestation at that time. The vegetation changes appear to be the result of changing patterns of land use in the centuries preceding the European arrival and the resulting devastation, whereas the cause of the CO
2
decline remains enigmatic.

Science
, this issue p.
484
The biologically optimized spacefarer
The Next 500 Years
Christopher E. Mason
MIT Press, 2021. 296 pp.
Authors: Szocik Konrad
Published: April 2021

A geneticist proposes a radical plan to help humanity live comfortably on other planets
Engineering small-ion transporter channels
Authors: Hinds Bruce J.
Published: April 2021

Voltage-gated channels microfabricated in graphene sheets act as ion-selective transistors
Household COVID-19 risk and in-person schooling
Authors: Lessler Justin , Grabowski M. Kate , Grantz Kyra H. , Badillo-Goicoechea Elena , Metcalf C. Jessica E. , Lupton-Smith Carly , Azman Andrew S. , Stuart Elizabeth A.
Published: April 2021

Back to school—safely

Severe COVID-19 in children is rare, but many schools remain closed because the transmission risk that school contact poses to adults and the wider community is unknown. Observing the heterogeneity of approaches taken among U.S. school districts, Lessler
et al.
investigated how different strategies influence COVID-19 transmission rates in the wider community using COVID-19 Symptom Survey data from Carnegie Mellon and Facebook. The authors found that when mitigation measures are in place, transmission within schools is limited and infection rates mirror that of the surrounding community.

Science
, abh2939, this issue p.
1092
Mental health after paediatric concussion: a systematic review and meta-analysis
Authors: Gornall Alice , Takagi Michael , Morawakage Thilanka , Liu Xiaomin , Anderson Vicki
Published: April 2021

Objective

This systematic review and meta-analysis sought to rigorously examine mental health outcomes following paediatric concussion. To date, heterogeneous findings and methodologies have limited clinicians’ and researchers’ ability to meaningfully synthesise existing literature. In this context, there is a need to clarify mental health outcomes in a homogeneous sample, controlling for key methodological differences and applying a consistent definition of concussion across studies.

Design

Systematic review and meta-analysis.

Data sources

We searched Medline, Embase, PsycINFO, CINAHL, SportDiscus, Scopus and PubMed.

Eligibility

Peer-reviewed studies published between 1980 and June 2020 that prospectively examined mental health outcomes after paediatric concussion, defined as per the Berlin Consensus Statement on Concussion in Sport.

Results

Sixty-nine articles characterising 60 unique samples met inclusion criteria, representing 89 114 children with concussion. Forty articles (33 studies) contributed to a random effects meta-analysis of internalising (withdrawal, anxiety, depression, post-traumatic stress), externalising (conduct problems, aggression, attention, hyperactivity) and total mental health difficulties across three time points post-injury (acute, persisting and chronic). Overall, children with concussion (n=6819) experienced significantly higher levels of internalising (g=0.41–0.46), externalising (g=0.25–0.46) and overall mental health difficulties compared with controls (g=0.18–0.49; n=56 271), with effects decreasing over time.

Summary/conclusions

Our review highlights that mental health is central to concussion recovery. Assessment, prevention and intervention of mental health status should be integrated into standard follow-up procedures. Further research is needed to clarify the mechanisms underlying observed relationships between mental health, post-concussion symptoms and other psychosocial factors. Results suggest that concussion may both precipitate and exacerbate mental health difficulties, thus impacting delayed recovery and psychosocial outcomes.
Care-seeking during fatal childhood illness in rural South Africa: a qualitative study
Authors: Price Jessica , Willcox Merlin , Dlamini Vuyiswa , Khosa Audrey , Khanyile Phindile , Seeley Janet , Harnden Anthony , Kahn Kathleen , Hinton Lisa
Published: April 2021

Objectives

This study aimed to better understand reasons why children in South Africa die at home, including caregivers’ care-seeking experiences, decision-making, choice of treatment provider and barriers to accessing care during a child’s final illness.

Design

This qualitative study included semi-structured in-depth interviews and focus group discussions with caregivers of children who died below the age of 5 years. Data were thematically analysed, and key findings compared with the Pathways to Survival Framework—a model frequently used in the study of child mortality. An adapted model was developed.

Setting

Two rural health and demographic surveillance system (HDSS) sites in South Africa—the Agincourt HDSS and the Africa Health Research Institute.

Participants

Thirty-eight caregivers of deceased children (29 participated in in-depth interviews and 9 were participants in two focus group discussions). Caregivers were purposively sampled to ensure maximum variation across place of death, child age at death, household socioeconomic status, maternal migration status and maternal HIV status.

Findings

Although caregivers faced barriers in providing care to children (including insufficient knowledge and poor transport), almost all did seek care from the formal health system. Negative experiences in health facilities did not deter care-seeking, but most respondents still received poor quality care and were not given adequate safety-netting advice. Traditional healers were only consulted as a last resort when other approaches had failed.

Conclusion

Barriers to accessing healthcare disrupt the workings of previously accepted care-seeking models. The adapted model presented in this paper more realistically reflects care-seeking experiences and decision-making during severe childhood illness in rural South Africa and helps explain both the persistence of home deaths despite seeking healthcare, and the impact of a child’s death on care-seeking in future childhood illness. This model can be used as the basis for developing interventions to reduce under-5 mortality.
Enablers and barriers to primary healthcare for Aboriginal and Torres Strait Islander adolescents: study protocol for participatory mixed-methods research that builds on WHO global standards
Authors: Ritchie Tirritpa , Purcell Tara , Westhead Seth , Wenitong Mark , Cadet-James Yvonne , Brown Alex , Kirkham Renae , Neville Johanna , Saleh Clara , Brown Ngiare , Kennedy Elissa C , Hennegan Julie , Pearson Odette , Azzopardi Peter S
Published: April 2021

Introduction

One-third of Australia’s Aboriginal and Torres Strait Islander population are adolescents. Recent data highlight their health needs are substantial and poorly met by existing services. To design effective models of primary healthcare, we need to understand the enablers and barriers to care for Aboriginal and Torres Strait Islander adolescents, the focus of this study.

Methods and analysis

This protocol was codesigned with Apunipima Cape York Health Council that supports the delivery of primary healthcare for 11 communities in Far North Queensland. We framed our study around the WHO global standards for high-quality health services for adolescents, adding an additional standard around culturally safe care. The study is participatory and mixed methods in design and builds on the recommended WHO assessment tools. Formative qualitative research with young people and their communities (exploring concepts in the WHO recommended quantitative surveys) seeks to understand demand-side enablers and barriers to care, as well as preferences for an enhanced response. Supply-side enablers and barriers will be explored through: a retrospective audit of clinic data (to identify current reasons for access and what can be strengthened); an objective assessment of the adolescent friendliness of clinical spaces; anonymous feedback from adolescent clients around quality of care received and what can be improved; and surveys and qualitative interviews with health providers to understand their perspectives and needs to provide enhanced care. This codesigned project has been approved by Apunipima Cape York Health Council and Far North Queensland Human Research Ethics Committee.

Dissemination and implications

The findings from this project will inform a codesigned accessible and responsive model of primary healthcare for Aboriginal and Torres Strait Islander adolescents.
Reducing time to X-ray in emergency department ambulatory patients: a quality improvement project
Authors: Kwok Matthew Mo Kin , Chiu Allison , Chia James , Hansen Cindy
Published: April 2021

This quality improvement project began when physicians and nurses at our hospital observed patients waiting for excessive periods of time for a porter to escort patients from the emergency department (ED) to medical imaging (MI). However, certain patients may not need staff escort and are able to ambulate from ED to MI by themselves. This would reduce waiting time from when the X-ray is ordered to X-ray being done, which may reduce overall ED length of stay and improve patients’ experience.

Our project aim is to decrease the time to X-ray by 50% within 6 months by having appropriate ambulatory patients walk from the ED to the X-ray department without a porter. To achieve our goal, several strategies were employed. First, brainstorm sessions were held to better understand the barriers and ways to implement the new process. Second, a patient survey was conducted to understand their thoughts on the change idea. Third, data were collected to assess the inefficiency problem on the number of times non-porter staff escorted patients due to porters being unavailable. A total of 14 PDSA (Plan-Do-Study-Act) cycles were completed between December 2018 and May 2019. A human factor specialist was consulted to examine the process for safety and optimisation of the patient journey.

In our PDSA cycles, self-ambulatory patients were compared with ambulatory patients who required an escort. An improvement was found from time to X-ray of 28 min (11 min vs 39 min). The new self-ambulatory process was implemented in June 2019 on a daily basis.
Effects of a refined evidence-based toolkit and mentored implementation on medication reconciliation at 18 hospitals: results of the MARQUIS2 study
Authors: Schnipper Jeffrey L , Reyes Nieva Harry , Mallouk Meghan , Mixon Amanda , Rennke Stephanie , Chu Eugene , Mueller Stephanie , Smith Jr Gregory (Randy) R , Williams Mark V , Wetterneck Tosha B , Stein Jason , Dalal Anuj , Labonville Stephanie , Sridharan Anirudh , Stolldorf Deonni P , Orav E John , Levin Brian , Gresham Marcus , Yoon Cathy , Goldstein Jenna , Platt Sara , Nyenpan Christopher Tugbéh , Howell Eric , Kripalani Sunil ,   and MARQUIS2 Site Leaders
Published: April 2021

Background

The first Multicenter Medication Reconciliation Quality Improvement (QI) Study (MARQUIS1) demonstrated that mentored implementation of a medication reconciliation best practices toolkit decreased total unintentional medication discrepancies in five hospitals, but results varied by site. The objective of this study was to determine the effects of a refined toolkit on a larger group of hospitals.

Methods

We conducted a pragmatic quality improvement study (MARQUIS2) at 18 North American hospitals or hospital systems from 2016 to 2018. Incorporating lessons learnt from MARQUIS1, we implemented a refined toolkit, offering 17 system-level and 6 patient-level interventions. One of eight physician mentors coached each site via monthly calls and performed one to two site visits. The primary outcome was number of unintentional medication discrepancies in admission or discharge orders per patient. Time series analysis used multivariable Poisson regression.

Results

A total of 4947 patients were sampled, including 1229 patients preimplementation and 3718 patients postimplementation. Both the number of system-level interventions adopted per site and the proportion of patients receiving patient-level interventions increased over time. During the intervention, patients experienced a steady decline in their medication discrepancy rate from 2.85 discrepancies per patient to 0.98 discrepancies per patient. An interrupted time series analysis of the 17 sites with sufficient data for analysis showed the intervention was associated with a 5% relative decrease in discrepancies per month over baseline temporal trends (adjusted incidence rate ratio: 0.95, 95% CI 0.93 to 0.97, p<0.001). Receipt of patient-level interventions was associated with decreased discrepancy rates, and these associations increased over time as sites adopted more system-level interventions.

Conclusion

A multicentre medication reconciliation QI initiative using mentored implementation of a refined best practices toolkit, including patient-level and system-level interventions, was associated with a substantial decrease in unintentional medication discrepancies over time. Future efforts should focus on sustainability and spread.
Association of imbalance between job workload and functional ability with return to work in ARDS survivors
Authors: Su Han , Hopkins Ramona O , Kamdar Biren B , May Susanne , Dinglas Victor D , Johnson Kurt L , Hosey Megan , Hough Catherine L , Needham Dale M , Thompson Hilaire J
Published: April 2021

Background

Inability to return to work (RTW) is common after acute respiratory distress syndrome (ARDS). Mismatch in an individual’s job workload and his or her functional ability, termed work ability imbalance, is negatively associated with RTW, but has not been evaluated in ARDS survivors.

Object

We examine associations between work ability imbalance at 6 months and RTW at 6 months and 12 months, as well as the ability to sustain employment in ARDS survivors.

Methods

Previously employed participants from the ARDS Network Long-Term Outcomes Study (N=341) were evaluated. Pre-ARDS workload was determined based on the US Occupational Information Network classification. Post-ARDS functional ability was assessed using self-reported 36-Item Short Form Health Survey (SF-36) physical functioning, social functioning and mental health subscales, and Mini-Mental State Examination. ARDS survivors were categorised into four work ability imbalance categories: none, psychosocial, physical, and both psychosocial and physical.

Results

Almost 90% of ARDS survivors had a physical and/or psychosocial work ability imbalance at both 6-month and 12-month follow-up. Compared with survivors with no imbalance at 6 months, those with both physical and psychosocial imbalance had lower odds of RTW (6 months: OR=0.33, 95% CI=0.13 to 0.82; 12 months: OR=0.22, 95% CI=0.07 to 0.65). Thirty-eight (19%) of those who ever RTW were subsequently jobless at 12 months.

Conclusion

Interventions aimed at rebalancing ARDS survivors’ work ability by addressing physical and psychosocial aspects of their functional ability and workload should be explored as part of efforts to improve RTW, maintain employment and reduce the financial impact of joblessness.
Paying lip service to publication ethics: scientific publishing practices and the Foundation for a Smoke-Free World
Authors: Legg Tess , Legendre Michél , Gilmore Anna B
Published: April 2021

Litigation forced the dissolution of three major tobacco industry-funded organisations because of their egregious role in spreading scientific misinformation. Yet in 2017, a new scientific organisation—the Foundation for a Smoke-Free World (FSFW)—was launched, funded entirely by tobacco corporation Philip Morris International (PMI). Experts fear FSFW similarly serves to benefit its funder’s scientific and political agenda. We present three case studies of FSFW’s publishing practices to explore: whether FSFW and its affiliates are acting with scientific integrity in their attempts to publish research; how conflicts of interest (COI) are governed in the journals FSFW targets; whether scientific publishing needs to be better protected from the tobacco industry in light of this, and if so, how. FSFW and its grantees have resorted to repeated obfuscation when publishing their science. FSFW staff have failed to act transparently and arguably have sought control over editorial processes (at times facilitated by PR firm, Ruder Finn). FSFW-funded organisations (including its Italian ‘Centre of Excellence’) and researchers affiliated with FSFW (including those working as editors and peer-reviewers) have failed to disclose their links to FSFW and PMI. While journals also failed to apply their COI policies, including on tobacco industry-funded research, the findings highlight that such policies are almost entirely dependent on researchers fully declaring all potential COIs. The paper explores ways to address these problems, including via standardised reporting of COI and funding in journals; journal policies prohibiting publication of tobacco industry-funded science; development of an author-centric database of financial interests; and legally mandated tobacco industry financial contributions to fund science on new tobacco and nicotine products.