bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cropping systems alter hydraulic traits of barley but not pea grown in mixture
Authors: Sun Qing , Gilgen Anna K. , Signarbieux Constant , Klaus Valentin H. , Buchmann Nina 
Published: March 2021

AbstractExtreme events such as drought and heatwaves are among the biggest challenges to agricultural production and food security. However, the effects of cropping systems on drought resistance of arable crops via their hydraulic behaviour remain unclear. We investigated how hydraulic traits of a field‐grown pea‐barley (Pisum sativum L. and Hordeum vulgare L.) mixture were affected by different cropping systems, that is, organic and conventional farming with intensive or conservation tillage. Xylem vulnerability to cavitation of both species was estimated by measuring the pressure inducing 50% loss of hydraulic conductivity (P50), while the water stress plants experienced in the field were assessed using native percentage loss of hydraulic conductivity (nPLC). Pea and barley showed contrasting hydraulic behaviours: pea was less vulnerable to xylem cavitation and less stressed than barley; cropping systems affected the xylem vulnerability of barley, but not of pea. Barley grown under conventional farming with no tillage was more vulnerable and stressed than under organic farming with intensive tillage. nPLC proved to be a valuable indicator for plant water stress. Our results highlight the impact of cropping systems on crop xylem vulnerability and drought resistance, thus plant hydraulic traits, for protecting food security under future climate.
The cell wall of green microalgae and its role in heavy metal removal
Authors: Spain Olivia , Plöhn Martin , Funk Christiane 
Published: March 2021

AbstractHeavy metals in industrial wastewaters are posing a serious threat to the environment and to human health. Microalgae are increasingly being seen as potential solutions to this problem as they can remove pollutants through biosorption. This process offers certain advantages over other more traditional metal removal techniques as it is simple, inexpensive, eco‐friendly, and can be performed over a wide range of experimental conditions. Biosorption is possible due to the unique and complex structure of the microalgal cell wall. The variety of functional groups on the surface of the cell wall (such as carboxyl or amino groups) can act as binding sites for the heavy metals, thus removing them from the environment. This review focuses on the cell wall composition and structure of the most commonly used microalgae in heavy metal removal and shows the role of their cell wall in the biosorption process. This review also aims to report the most commonly used models to predict the velocity of microalgal biosorption and the removal capacities.
Estimation of the Size of Informal Employment Based on Administrative Records With Non-Ignorable Selection Mechanism
Authors: Berȩsewicz Maciej , Nikulin Dagmara 
Published: March 2021

AbstractIn this study, we used company level administrative data from the National Labour Inspectorate and The Polish Social Insurance Institution in order to estimate the prevalence of informal employment in Poland in 2016. Since the selection mechanism is non-ignorable, we employed a generalization of Heckman’s sample selection model assuming non-Gaussian correlation of errors and clustering by incorporation of random effects. We found that 5.7% (4.6%, 7.1%; 95% CI ) of registered enterprises in Poland, to some extent, take advantage of the informal labour force. Our study exemplifies a new approach to measuring informal employment, which can be implemented in other countries. It also contributes to the existing literature by providing, to the best of our knowledge, the first estimates of informal employment at the level of companies based solely on administrative data.
Multidimensional parameter estimation of heavy‐tailed moving averages
Authors: Ljungdahl Mathias Mørck , Podolskij Mark 
Published: March 2021

AbstractIn this article we present a parametric estimation method for certain multiparameter heavy‐tailed Lévy‐driven moving averages. The theory relies on recent multivariate central limit theorems obtained via Malliavin calculus on Poisson spaces. Our minimal contrast approach is related to previous papers, which propose to use the marginal empirical characteristic function to estimate the one‐dimensional parameter of the kernel function and the stability index of the driving Lévy motion. We extend their work to allow for a multiparametric framework that in particular includes the important examples of the linear fractional stable motion, the stable Ornstein–Uhlenbeck process, certain CARMA(2, 1) models, and Ornstein–Uhlenbeck processes with a periodic component among other models. We present both the consistency and the associated central limit theorem of the minimal contrast estimator. Furthermore, we demonstrate numerical analysis to uncover the finite sample performance of our method.
Are School Reopening Decisions Related to Union Influence?
Authors: DeAngelis Corey A. , Makridis Christos 
Published: March 2021

ObjectiveThe COVID‐19 pandemic led to widespread school closures affecting millions of K‐12 students in the United States in the spring of 2020. Groups representing teachers have pushed to reopen public schools virtually in the fall because of concerns about the health risks associated with reopening in person. In theory, stronger teachers’ unions may more successfully influence public school districts to reopen without in‐person instruction.MethodsWe examine the relationship between teachers’ union strength and the reopening decisions of 835 public school districts in the United States using regression analyses.ResultsWe find that school districts in locations with stronger teachers’ unions are less likely to reopen in person even after we control semiparametrically for differences in local demographic characteristics. These results are robust to four measures of union strength, various potential confounding characteristics, a further disaggregation to the county level, and various analytic techniques and datasets. We do not find evidence that measures of COVID‐19 risk are correlated with school reopening decisions.ConclusionOur findings that school closures are uncorrelated with the actual incidence of the virus, but are rather strongly associated with unionization, implies that the decision to close schools has been a political—not scientific—decision.
Reanalysis of the apoid wasp phylogeny with additional taxa and sequence data confirms the placement of Ammoplanidae as sister to bees
Authors: Sann Manuela , Meusemann Karen , Niehuis Oliver , Escalona Hermes E. , Mokrousov Mikhail , Ohl Michael , Pauli Thomas , Schmid‐Egger Christian 
Published: March 2021

AbstractApoid wasps and bees (Apoidea) are an ecologically and morphologically diverse group of aculeate Hymenoptera (ants, bees and wasps). During the last decades, significant progress has been made in illuminating the phylogenetic relationships of the major Apoidea lineages. However, some uncertainties have remained. In this study, we present results from re‐investigating the phylogeny of Apoidea by including genome skimming data of key taxa that were missing in previous investigations: a representative of Entomosericini (tribe of the former Pemphredoninae) and a representative of Eremiaspheciinae (subfamily of the former ‘Crabronidae’). We additionally skimmed the genomes of two Heterogyna species (Heterogynaidae). Our results from applying concatenation and coalescence‐based phylogenetic approaches confirm the previously suggested sister group relationship of Ammoplanidae and bees. They also corroborate most taxonomic changes published in 2018 granting eight lineages of the former family ‘Crabronidae’ family status. However, some of our analyses indicate that the families Pemphredonidae and Psenidae could be para‐ or polyphyletic. After carefully assessing topological discordance and data quality, the exact placements of Heterogyna and of the genera Eremiasphecium and Entomosericus in the apoid wasp phylogeny remain ambiguous. However, our analyses indicate that inclusion of Entomosericus and Eremiasphecium in any of the currently accepted apoid wasp families cannot be well justified, and we consequently suggest raising Entomosericinae and Eremiaspheciini to family rank, respectively, to acknowledge this situation in the apoid classification: Entomosericidae Dalla Torre, 1897 (stat. n.) and Eremiaspheciidae Menke, 1967 (stat. n.).
Turbulence Anisotropy Investigations in an Internal Combustion Engine
Authors: MacDonald James R. , Fajardo Claudia M. 
Published: March 2021

Abstract
The assumption of isotropic turbulence is commonly incorporated into models of the internal combustion engine (ICE) in-cylinder flows. While preliminary analysis with two-dimensional (2D) velocity data indicates that the turbulence may tend to isotropy as the piston approaches top-dead-center (TDC), the validity of this assumption has not been fully investigated, partially due to the lack of three-component velocity data in ICEs. In this work, the velocity was measured using two-dimensional, three-component (2D-3C) particle image velocimetry in a single-cylinder, motored, research engine to investigate the evolution of turbulence anisotropy throughout the compression stroke. Invariants of the Reynolds stress anisotropy tensor were calculated and visualized, through the Lumley triangle, to investigate turbulence states. Results showed the turbulence to be mostly anisotropic, with preferential tendency toward 2D axisymmetry at the beginning of the compression stroke and approaching-isotropy near top-dead-center. Findings provide new insights into turbulence in dynamic, bounded flows to assist with the development of physics-based, quantitative models.
Thermal Analysis of Paraffin-Embedded Tissue Blocks for Anatomic Pathology Processes
Authors: Ciancia Sabrina , Lucantonio Alessandro , Vannozzi Lorenzo , Pedrazzini Gian Andrea , Ricotti Leonardo 
Published: March 2021

AbstractWe analyze temperature dynamics in anatomic pathology samples to identify the most efficient refrigeration method and to predict the time available for optimal sectioning before sample heating, thus getting appropriate information for a correct diagnosis by anatomopathologists. A thermal finite element (FE) analysis was carried out with comsolmultiphysics to evaluate temperature variations in paraffin-embedded tissues, i.e., muscle, bone and fat, and the corresponding thermal stresses. Experiments with different tissues and thermocouple-based measurements allowed validating the FE simulations. Simulations allowed to estimate the time needed to bring the sample at the optimal temperature for sectioning (−8 to −4 °C) in different conditions: refrigeration on a cold plate, refrigeration in a cooled environment, and refrigeration in an environment with forced convection. Among the three cooling methods tested, the forced convection at −20 °C and with an air-flow speed of 5 m/s resulted in the shortest cooling time. As compared to the other methods, thermal stresses can be modulated by varying the air-flow speed. For the different conditions, the time needed for the surface of the tissue block to exit from a temperature corresponding to an optimal cutting, when leaving the sample exposed to room temperature after refrigeration, ranged from 12 to 310 s. We quantify the time needed to adequately refrigerate paraffin-embedded tissue samples and the time available before they leave the optimal temperature window for sectioning. We also evaluate the maximum stress attained in the paraffin block during the cooling and the heating transients. This information will help optimize anatomic pathology processes.
Blood Flow Velocimetry in a Microchannel During Coagulation Using Particle Image Velocimetry and Wavelet-Based Optical Flow Velocimetry
Authors: Kucukal E. , Man Y. , Gurkan Umut A. , Schmidt B. E. 
Published: March 2021

Abstract
This article describes novel measurements of the velocity of whole blood flow in a microchannel during coagulation. The blood is imaged volumetrically using a simple optical setup involving a white light source and a microscope camera. The images are processed using particle image velocimetry (PIV) and wavelet-based optical flow velocimetry (wOFV), both of which use images of individual blood cells as flow tracers. Measurements of several clinically relevant parameters such as the clotting time, decay rate, and blockage ratio are computed. The high-resolution wOFV results yield highly detailed information regarding thrombus formation and corresponding flow evolution that is the first of its kind.
In Silico Finite Element Analysis of the Foot Ankle Complex Biomechanics: A Literature Review
Authors: Phan P. K. , Vo A. T. N. , Bakhtiarydavijani A. , Burch R. , Smith B. , Ball J. E. , Chander H. , Knight A. , Prabhu R. K. 
Published: March 2021

Abstract
Computational approaches, especially finite element analysis (FEA), have been rapidly growing in both academia and industry during the last few decades. FEA serves as a powerful and efficient approach for simulating real-life experiments, including industrial product development, machine design, and biomedical research, particularly in biomechanics and biomaterials. Accordingly, FEA has been a “go-to” high biofidelic software tool to simulate and quantify the biomechanics of the foot–ankle complex, as well as to predict the risk of foot and ankle injuries, which are one of the most common musculoskeletal injuries among physically active individuals. This paper provides a review of the in silico FEA of the foot–ankle complex. First, a brief history of computational modeling methods and finite element (FE) simulations for foot–ankle models is introduced. Second, a general approach to build an FE foot and ankle model is presented, including a detailed procedure to accurately construct, calibrate, verify, and validate an FE model in its appropriate simulation environment. Third, current applications, as well as future improvements of the foot and ankle FE models, especially in the biomedical field, are discussed. Finally, a conclusion is made on the efficiency and development of FEA as a computational approach in investigating the biomechanics of the foot–ankle complex. Overall, this review integrates insightful information for biomedical engineers, medical professionals, and researchers to conduct more accurate research on the foot–ankle FE models in the future.
Two-Segment Flexible Macintosh Laryngoscope to Improve Glottic Visualization During Endotracheal Intubation
Authors: Sand Yashovardhan , Erdman Arthur G. , Konia Mojca R. 
Published: March 2021

Abstract
Endotracheal intubation is a frequently performed life-saving procedure in medicine. Obtaining view of glottic structures is essential for successful completion of endotracheal intubation. Most frequently used devices called laryngoscopes sometimes fail to obtain view, which would allow for a successful completion of endotracheal intubation. To improve visualization of glottic structures, practitioners can use high-tech video-laryngoscopes, but these are not available to everyone, especially not in the third world countries. Alternatively, practitioners can use two-segment laryngoscopes. We developed a prototype of a two-segment flexible laryngoscope and tested it in a simulated environment. The glottic visualization statistically significantly (p = 0.000038) improved with the use of flexible laryngoscope. Our study strengthens available evidence that multisegment laryngoscope blades can improve glottic visualization and decrease forces exerted on soft tissues of larynx.
A Computer-Aided Fixture Design System With Process Planning Integration for Prismatic Parts Manufactured on CNC Machining Centers
Authors: Prombanpong S. , Lewis R. L. , Bishop A. B. 
Published: March 2021

Abstract
Jigs and fixtures are indispensable tools in various manufacturing processes. These processes include metal removal, assembly, welding, and inspection processes. Not only do jigs and fixtures facilitate the operations, but also provide quick loading/unloading, proper and consistent supporting and locating of a workpiece. As a result, the workpiece can be manufactured economically in proportion to the volume of production.
With the advent of computer aided design and computer aided manufacturing together with an increasing power of both computer hardware and software, computerized fixture design systems become feasible and more sophisticated. The current computerized fixture design systems are developed utilizing several approaches ranging from simple interactive placement of fixture components to sophisticated generative systems. However, one of the common drawbacks of these systems is a lack of process planning integration in the fixture design considerations. As a result, the contradiction between fixture design generated by the computerized fixture design system and a process plan generated by a process planner or by computer aided process planning software always occurs. In other words, the fixture set-ups and workpiece orientation are not congruent to the process plan.
This paper serves to discuss a solution to the problem mentioned above. A mathematical model was developed to integrate process planning in fixture design considerations. An optimized fixture design system will be presented and discussed. Examples of tested cases are also presented.
Automated Gating Plan Synthesis for Injection Molds
Authors: Saxena Mukul , Irani Rohinton K. 
Published: March 2021

Abstract
The task of design synthesis can be accomplished by human beings because of their ability to take into account the physics of the problem, past experience, and to evaluate a number of alternatives to determine the best compromise design. This paper illustrates a system that automates this procedure for injection mold design, and more specifically, gating design. The gating plan synthesis system described in this paper, automatically determines an initial gating configuration based on a features representation of the part and a knowledge-base that captures some of the design rules used in practice. A Feature Modeling Utility (FMU), a Topology and Geometry Utility System (TAGUS), and an automatic mesh generator, OCTREE, are used to identify and query features and to perform geometric reasoning about the part. The methodology used, implementation details, and examples of test cases are presented.
Minkowski Sums: A Simulation Tool for CAD/CAM
Authors: Kaul Anil 
Published: March 2021

Abstract
In this paper we provide a survey of Minkowski sums, their applications as a simulation tool in Computer Aided Design and some simple algorithms to compute them. The intent of the paper is to exhibit the relevance of morphological operations, like Minkowski sums, in practical aspects of CAD/CAM and to provide enough motivation to stimulate research in finding efficient algorithms for their computation. Except for cases where the two initial objects are convex, there are no known algorithms which guarantee efficient performance in the polyhedral domain. Some initial work has been done for finding algorithms where the boundaries of the objects are composed of algebraic curves, but again very little is known on how to actually compute the Minkowski sum for objects bounded by general curves. Some of the applications that we describe in this paper include Robot path planning, interference detection, NC cutter path planning, rounding and filleting, shape design, etching and deposition processes in semiconductor process simulation and polyhedral interpolation.
A Computer Model for Thermofluid Analysis of Vehicle Cooling Systems
Authors: Veshagh Alireza , Chen Changyou , Moffatt Richard 
Published: March 2021

Abstract
This paper describes a computer model developed for analysing the thermofluid performance of vehicle cooling systems. The model has a modular structure which links various system submodels. The individual component submodels can be extended and modified in order to conduct parametric studies to examine the effects of various design and operating parameters on performance. The model can predict the overall thermal performance of the vehicle heating and cooling systems, providing useful information at the early stages of the design and development. In this paper, details of each submodel are described together with the overall structure of the vehicle model. The model predictions are compared with measured data and the application of the model is illustrated by several test cases.
Parallel Substructure Approach for Massively Parallel Computers
Authors: Fulton Robert E. , Su Philip S. 
Published: March 2021

Abstract
New massively parallel computer architectures have revolutionized the design of computer algorithms, and promise to have significant influence on algorithms for engineering computations. The traditional global model parallel method has a limited benefit for massively parallel computers. An alternative method is to use the substructure approach. This paper is to explore the potential for substructure strategy through actual examples. Each substructure is mapped on to some processors of a MIMD parallel computer. The internal nodes variables will be condensed into boundary nodes variables in each substructure. All substructures computations can be performed in parallel until the global boundary system equation is formed. A direct solution strategy for the global boundary displacements is performed. The final internal nodes displacements solution in each substructure can be performed in parallel. Examples for two-dimensional static analysis are presented on a BBN Butterfly GP1000 parallel computer.
Belt Vibration Consideration Moving Contact and Parametric Excitation
Authors: Yue M. G. 
Published: March 2021

Abstract
The contacting point between belt and pulley is not fixed but moves along the pulley during vibration and that influences the free span length of the belt. The concept vibrating length is introduced and that will affect the dynamic behavior of the belt.
Parametric excitation can occur through periodic variations in belt tension and speed arising from loading of the pulleys by belt-driven accessories and from engine in automotive applications. The most violent oscillations develop and resonance will occur when the frequency of excitation is close to twice or three times the natural frequency for varying tension and speed case, respectively.
Computer Simulation Program of Dynamic Analysis for Planetary Transmission
Authors: Ming Mao , Ruiting Cheng 
Published: March 2021

Abstract
Based on the angular velocity transformation matrix, the paper develops the differential motion equation BKTJBKdωIK/dt=BKTM for a planetary transmission, which is a linearly constrained system. Although the degrees-of-freedom of the system is varying during shift process, the angular velocity transformation matrix BK, whose entries are constans, is only related to engaged clutches and BK can be easily derived from a constant matrix BF by linear transformation. Based on this theory, a computer simulation program of dynamic analysis of a planetary transmission is written, which provides a perfect means for analysis of dynamic behaviour of a transmission at any shifting transients. As an illustration, that of an Allison-WT transmission from 3rd speed to 4th speed is simulated.