bluuebunny/crossref_metadata_2025 huggingface dataset:
Leadership, gender, and colorism: Children in India use social category information to guide leadership cognition
Authors: Santhanagopalan Radhika , Heck Isobel A. , Kinzler Katherine D.
Published: December 2021

Across the globe, women and racial minorities are underrepresented in leadership. We examined the development of 5–10‐year‐old children's leadership cognition in India, the world's largest democracy. This cultural context offered the opportunity to study the development of attitudes about gender and to extend examinations of children's conceptions of race to include colorism (the privileging of lighter skin). In Experiment 1, children completed a novel Election Task in which they saw a fictional class with 20 students varying in gender (boys, girls) and race/skin tone (darker‐skinned South Asian [Dark‐SA], lighter‐skinned South Asian [Light‐SA], Black, White). Children predicted who would be elected as President, Treasurer, Welcomer, and Notetaker. Children most often chose Light‐SA and White students as President. When choosing Presidents, younger children showed an own‐gender bias, but by age 9, both boys and girls primarily chose boy Presidents. Importantly, children's choices differed for the other class positions. Next, we asked children to draw a “leader.” No boys drew a girl, and girls’ drawings were mixed (52% drew girls). In Experiment 2, we replicated the drawing task findings and compared children's drawings of a leader to their drawings of a helper and a scientist. Children most often drew boys and men as leaders and scientists, but not as helpers, suggesting specificity of children's pro‐male bias to male‐stereotyped positions. Children's conceptions of leadership reflected a male bias and an association between lighter skin and status.
Sahul's megafauna were vulnerable to plant‐community changes due to their position in the trophic network
Authors: Llewelyn John , Strona Giovanni , McDowell Matthew C. , Johnson Christopher N. , Peters Katharina J. , Stouffer Daniel B. , de Visser Sara N. , Saltré Frédérik , Bradshaw Corey J. A.
Published: December 2021

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom–up cascades occur when changes in the primary producers in a network elicit flow‐on effects to higher trophic levels. However, it remains unclear what determines a species' vulnerability to bottom–up cascades and whether such cascades were a large contributor to the megafauna extinctions that swept across several continents in the Late Pleistocene. The pathways to megafauna extinctions are particularly unclear for Sahul (landmass comprising Australia and New Guinea), where extinctions happened earlier than on other continents. We investigated the potential role of bottom–up trophic cascades in the megafauna extinctions in Late Pleistocene Sahul by first developing synthetic networks that varied in topology to identify how network position (trophic level, diet breadth, basal connections) influences vulnerability to bottom–up cascades. We then constructed pre‐extinction (~80 ka) network models of the ecological community of Naracoorte, south‐eastern Sahul, to assess whether the observed megafauna extinctions could be explained by bottom–up cascades. Synthetic networks showed that node vulnerability to bottom–up cascades decreased with increasing trophic level, diet breadth and basal connections. Extinct species in the Naracoorte community were more vulnerable overall to these cascades than were species that survived. The position of extinct species in the network – tending to be of low trophic level and therefore having relatively narrow diet breadths and fewer connections to plants – made them vulnerable. However, these species also tended to have few or no predators, a network‐position attribute that suggests they might have been particularly vulnerable to new predators. Together, these results suggest that trophic cascades and naivety to predators could have contributed to the megafauna extinction event in Sahul.
Who is afraid of sanctions? The macroeconomic and distributional effects of the sanctions against Iran
Authors: Ghomi Morteza
Published: December 2021

The sanctions imposed on Iran at the beginning of 2012 have simultaneously limited the country's access to the international financial system, levied a strict boycott on Iran's oil and petrochemical exports, and limited imports of intermediate goods. This paper tries to quantify the aggregate and heterogeneous effects of these sanctions. Applying the synthetic control method, I show that the sanctions had persistent and significant effects on the Iranian economy. The cost reached its maximum of 19.1% of real gross domestic product 4 years after the application of the sanctions, and the economy has not fully recovered after their removal. I trace the poverty dynamics for different household groups after the sanctions by adopting a synthetic panel using Iran's household income and expenditure survey data. Inconsistently with the sanctions' initial goals, poverty dynamics suggest that households working in governmental sectors and educated households are unaffected by the sanctions. Instead, the sanctions condemn young, illiterate, rural, or religious minority households to poverty.
Decoupled richness of generalist anaerobes and sulphate‐reducing bacteria is driven by pH across land uses in temperate soils
Authors: George Paul B. L. , Coelho Katia P. , Creer Simon , Lebron Inma , Robinson David A. , Jones Davey L.
Published: December 2021

Sulphate‐reducing bacteria (SRB) represent a key biological component of the global sulphur (S) cycle and are common in soils, where they reduce SO42− to H2S during the anaerobic degradation of soil organic matter. The factors that regulate their distribution in soil, however, remain poorly understood. We sought to determine the ecological patterns of SRB richness within a nationwide 16S metabarcoding dataset. Across 436 sites belonging to seven contrasting temperate land uses (e.g., arable, grasslands, woodlands, heathland and bog), SRB richness was relatively low across land uses but greatest in grasslands and lowest in woodlands and peat‐rich soils. There was a shift in dominant SRB taxa from Desulfosporosinus and Desulfobulbus in arable and grassland land uses to Desulfobacca in heathland and bog sites. In contrast, richness of other generalist anaerobic bacterial taxa found in our dataset (e.g., Clostridium, Geobacter and Pelobacter) followed a known trend of declining richness linked to land‐use productivity. Overall, the richness of SRBs and anaerobes had strong positive correlations with pH and sulphate concentration and strong negative relationships with elevation, soil organic matter, total carbon and carbon‐to‐nitrogen ratio. It is likely that these results reflect the driving influence of pH and competition for optimal electron acceptors with generalist anaerobic bacteria on SRB richness.

Highlights

Sulphate‐reducing bacteria (SRB) are key but rare soil biota that may compete with other anaerobes

As UK sulphur deposition rates fall, local populations of SRB may also decline in soils

Sulphate concentrations were higher in arable and wooded sites, not at higher elevation as expected

SRB richness was lower than generalist anaerobes, with peaks in grasslands and a drop in lowland woods.
Minimum standards for inpatient long‐term video‐electroencephalographic monitoring: A clinical practice guideline of the International League Against Epilepsy and International Federation of Clinical Neurophysiology
Authors: Tatum William O. , Mani Jayanti , Jin Kazutaka , Halford Jonathan J. , Gloss David , Fahoum Firas , Maillard Louis , Mothersill Ian , Beniczky Sandor
Published: December 2021

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long‐term video‐electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using the PRISMA (Preferred Reporting Items for Systematic Review and Meta‐Analysis) statement. We found limited high‐level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events. For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long‐term outcome effects of LTVEM and to establish its clinical utility.
Efficacy of herbal‐ versus chlorhexidine‐based mouthwashes towards oral hygiene maintenance in patients undergoing fixed orthodontic therapy: A systematic review and meta‐analysis
Authors: Kommuri Karthik , Michelogiannakis Dimitrios , Barmak Basir A. , Rossouw P. Emile , Javed Fawad
Published: December 2021

Background and objective

The review aims to fill the gap in literature by comparing the efficacy of herbal and chlorhexidine‐based mouthwashes towards oral hygiene maintenance (OHM) in patients undergoing fixed orthodontic treatment (OT).

Methods

Indexed databases were searched electronically to include randomized controlled trials (RCTs) for data gathering. The protocol was registered in PROSPERO (CRD42020182497). Risk of bias assessment, quality of evidence investigation and meta‐analysis were performed to evaluate reported OHM‐related parameters at time points before and after the use of chlorhexidine (control group) and herbal mouthwashes (intervention group). With 95% confidence intervals, mean difference (MD) or standardized mean difference (SMD) was used to estimate effect size.

Results

Out of eight RCTs, results from one RCT favoured chlorhexidine and the results from a second RCT favoured herbal mouthwashes. Results from three RCTs showed comparable effects for the respective investigated OHM‐related parameters. Chlorhexidine demonstrated higher antimicrobial efficacy againstStreptococcus mutans (S. mutans)in two studies, and one RCT found comparable antimicrobial efficacies. Risk of bias was low in two studies, and moderate and high in two studies each. Quality of evidence was very low to moderate for the respective investigated parameters. Sub‐group analysis for parameters colony forming units (CFU) {SMD (0.40) [95% CI (−0.22, 1.03)], gingival index (GI) {MD (0.06) [95% CI (−0.08, 0.20)]}, plaque index (PI) {SMD 0.22 [95% CI (−0.23, 0.67)]} before the use of chlorhexidine and herbal mouthwashes remained inconclusive.

Conclusion

The comparison between efficacy of herbal and chlorhexidine towards OHM in patients undergoing fixed OT remains debatable.
Grain boundary energies in yttria‐stabilized zirconia
Authors: Dillon Shen J. , Shen Yu‐Feng , Rohrer Gregory S.
Published: December 2021

The three‐dimensional microstructure of 8% yttria‐stabilized zirconia (YSZ) was measured by electron backscatter diffraction and focused ion beam serial sectioning. The relative grain boundary energies as a function of all five crystallographic grain boundary parameters were determined based on the assumption of thermodynamic equilibrium at the internal triple junctions. Grain boundaries with (100) orientations have low energies compared to boundaries of other orientations, and all [100] twist boundaries have relatively low energies. Other classes of boundaries with lower than average energies include [100] symmetric tilt boundaries with disorientations less than 40° and [111] twist boundaries with disorientations greater than 20°. At fixed misorientations, the relative areas of boundaries are inversely correlated to the relative grain boundary energy. The results suggest that texturing microstructures to increase the relative areas of [100] twist boundaries might increase the oxygen ion conductivity of YSZ ceramics.
Luting indirect restorations with resin cements versus composite resins: Effects of preheating and ultrasound energy on film thickness
Authors: Falacho Rui I. , Marques Joana A. , Palma Paulo J. , Roseiro Luís , Caramelo Francisco , Ramos João Carlos , Guerra Fernando , Blatz Markus B.
Published: December 2021

Objective

This study aims to evaluate and compare the film thickness obtained with a resin cement and two composite resins, preheated and/or ultrasonically vibrated, as luting agents.

Materials and methods

One hundred and twenty‐six (126) pairs of resin discs were randomly assigned to six experimental groups (n = 21) according to luting agent (Variolink Esthetic LC, IPS Empress Direct or Estelite Omega) and cementation technique (preheating at 68°C and/or ultrasonic vibration). Specimens were luted by applying a controlled force. Following sectioning and film thickness measurement through field emission gun scanning electron microscopy, statistical analysis was carried out considering a 5% significance level.

Results

Statistically significant lower film thickness was observed in Variolink Esthetic LC group when compared to all composite resin groups (p < 0.001), except IPS Empress Direct preheated and ultrasonically vibrated group (p = 0.073). IPS Empress Direct with ultrasonic vibration yielded statistically lower film thickness values than Estelite Omega groups, regardless of luting technique (p < 0.05). Ultrasonically vibrated Estelite Omega groups showed statistically lower film thickness values than solely preheated groups (p < 0.05).

Conclusions

Both Variolink Esthetic LC and IPS Empress Direct preheated and ultrasonically vibrated provided the lowest film thickness. The addition of ultrasonic vibration during cementation proved to be effective in reducing film thickness of both tested composite resins.

Clinical significance

The cementation technique will have variable results depending on the luting material. Adhesive cementation protocols with composite resins should mainly consider ultrasonic vibration, but also preheating, as strategies for reducing film thickness. The tested resin cement, alongside with IPS Empress Direct composite resin preheated and ultrasonically vibrated, provided the lowest film thickness among the tested materials and techniques.
Management of pregnancy and delivery in women with transposition of the great arteries after atrial switch operation: A 16‐year single‐center experience
Authors: Harada Gen , Inai Kei , Shimada Eriko , Ishido Mikiko , Shinohara Tokuko , Ogawa Masaki
Published: December 2021

Aim

This study aimed to summarize cases of successful pregnancy and delivery in patients with transposition of the great arteries (TGA) after atrial switch operation (ASO), to provide management, clinical experience, and maternal and fetal outcomes.

Methods

During a 16‐year period (2004–2019), we experienced 30 pregnancies in 15 patients after ASO at our institution. We retrospectively reviewed the medical records of the patients.

Results

In 30 pregnancies, there were 21 (70%) live births, five (17%) miscarriages, and four (13%) artificial abortions. There were no maternal or neonatal deaths. Cardiac complications occurred in nine (43%) patients: deterioration of right ventricular (RV) function in one, symptomatic heart failure (HF) in three, supraventricular tachyarrhythmia requiring electrical cardioversion in two, sick sinus syndrome that required pacemaker implantation in two, and hemoptysis in one. Obstetric complications occurred in five (24%). Neonatal complications were premature births (delivery at <37 weeks of gestation) in 15 (71%), and birthweight <2500 g in 18 (86%). The mode of delivery consisted of vaginal delivery (VD) in five (24%), and cesarean section (CS) in 16 (76%).

Conclusion

A high incidence of preterm CS and cardiac complications including deterioration of RV function was observed in patients who had undergone ASO for TGA.
Observation of pregnancy outcomes in patients with hysteroscopic resection on submucous myomas
Authors: Yang Yeping , Yang Yisai , You Min , Chen Lan , Sun Feng
Published: December 2021

Objective

The aim of this study was to assess postoperative pregnancy outcomes in patients with different types of submucous myomas after hysteroscopic resection.

Materials and Methods

This retrospective unicentric study used data from the electronic medical records system of the hospital. All patients (n = 77) who underwent hysteroscopy for submucous myomas between November 2010 and December 2018 were included. Patients were divided into three groups according to the myoma classification (G0, G1, and G2). Medical files were reviewed and phone questionnaires were conducted to evaluate demographic characteristics, clinical features, surgical treatment, and pregnancy outcomes.

Results

The median age of the patients was 32 (30.0, 34.0) years. The myoma diameter was 2.9 (2.0, 3.8) cm. The operation duration was 50.0 (30.0, 75.0) min. There were 15 patients in Group G0, 20 patients in Group G1, and 37 patients in Group G2. Follow‐up data were available for 65 of the 77 patients. The total pregnancy rate was 58 (89.2%) of 65. The live birth rate was 41 (70.7%) of 58. There was no significant difference in pregnancy rate (G0 100% vs. G1 76.5% vs. G2 91.2%; p = 0.097) or in live birth rates among the three groups (G0 78.6% vs. G1 53.8% vs. G2 74.2%; p = 0.325).

Conclusion

There was no difference in pregnancy outcome among the three types of submucosal myomas. Our results support the idea that hysteroscopic myomectomy is an effective option for submucous myomas with good long‐term pregnancy outcomes.
“Thank u, next”? Repartnering and the household division of labor
Authors: Ophir Ariane
Published: December 2021

Objective

Drawing on life course and gender theories, this study tests competing hypotheses about the effect of repartnering on women's and men's levels and shares of housework.

Background

Amidst increasing cohabitation rates and union instability, women and men are likely to form and dissolve multiple marital and nonmarital unions with different partners over the life course. However, most of our knowledge about the role of past relationships are based on cross‐sectional studies comparing first‐ and higher‐order union. This study investigates whether people change their housework arrangements upon repartnering and whether women and men experience similar patterns of change in heterosexual relationships.

Method

The analysis draws on 40 years of longitudinal data from the Panel Study of Income Dynamics and a sample of 1897 women and men who were observed in two sequential heterosexual unions. The author used fixed effects models to estimate change in housework behavior upon repartnering.

Results

Overall, the results show stability in housework behavior upon repartnering once controlling for other life course changes that concur with repartnering. Women continued doing the majority of housework upon repartnering.

Conclusion

The results suggest that forming a new heterosexual union evokes gender scripts which overall maintains the gendered housework behavior. Although housework is dynamic over the life course, the gender dynamics that shape housework is stable amid union instability.
Defocused contrast sensitivity function in peripheral vision
Authors: Jaisankar Durgasri , Suheimat Marwan , Rosén Robert , Atchison David A
Published: December 2021

Purpose

Human peripheral detection performance is affected by optical factors such as defocus and higher order aberrations. From optical theory, we would expect defocus to produce local depressions (notches) in the contrast sensitivity function (CSF). However, such notches have not been observed in peripheral vision, and it is unknown whether human peripheral vision can detect local depressions (notches) in the CSF, such as those produced by monochromatic defocus when all monochromatic ocular aberrations are corrected. The purpose of the study was to identify such notches.

Methods

Participants were three adult emmetropes. Following full adaptive optics correction, on‐axis and 20° nasal visual field detection CSFs in monochromatic light were measured for the right eye with a 7 mm diameter pupil, both without and with ±2 D defocus, and with separate determinations for horizontal and vertical gratings. Defocused CSFs were compared with predictions based on theoretical modulation transfer functions.

Results

Notches in the monochromatic defocused CSFs were identified for peripheral vision at optically predicted spatial frequencies with other monochromatic ocular aberrations corrected, provided that there was adequate spatial frequency sampling. The spatial frequencies of notches were similar to those predicted from optical theory, but their depths (0.3 to 0.9 log unit) were smaller than predicted.

Conclusion

With fine spatial frequency sampling, notches were identified in defocused monochromatic CSFs when all other monochromatic ocular aberrations were corrected, both on‐axis and at 20° eccentricity. Unless recognised as such, notches may contribute to noise in through‐focus detection measurements of peripheral visual performance.
Understanding pediatric ventilation in the operative setting. Part I: Physical principles of monitoring in the modern anesthesia workstation
Authors: Spaeth Johannes , Schumann Stefan , Humphreys Susan
Published: December 2021

The modern anesthesia workstation provides a wealth of information some of which is of particular interest when it comes to optimizing ventilation settings. This knowledge gains even more importance in the therapy of pediatric patients. In the absence of evidence‐based recommendations on optimal ventilation settings in pediatric patients, the evaluation of individual factors becomes crucial and challenging at the same time. Even when equipped with the latest sensor technology, the user will always have to be in charge of interpreting the provided monitoring variables. The purpose of this review is to outline the clinical impact, technological background, and reliability of the most relevant information measured and calculated by a modern anesthesia workstation. It aims at translating the technical knowledge into a more competent and vigilant application in the clinical setting.
Youth Political Mobilization: Violence, Intimidation, and Patronage in Zimbabwe
Authors: Maringira Godfrey , Gukurume Simbarashe
Published: December 2021

In this article, we argue that the “making” and deployment of political violence can be construed as hard work, in which political elites mobilize those from below to sustain their positions through the mobilization and doing of violence against perceived opposition political parties and or individuals. The article examines the ways in which former President Robert Mugabe instrumentalized his political relationship with his clients as a tool of political mobilization and perpetrating political violence in urban spaces where his electoral support base had dwindled. We argue that one of the remarkable ways in which Mugabe was able to remain in power for three decades was through his ability to creatively transform his influence and political position into a source of opportunities for his political clients, in particular the youth. We, therefore, assert that Mugabe extended and maintained his political patrimonial relationship with youths who did the work of political violence for him and his ZANU‐PF party. The mobilization of youth political violence is therefore an “art of governing” from below. This article is based on ethnographic data collected between 2016 and 2017 from youth in Harare. We conducted in‐depth interviews, life‐history interviews, observations, and informal conversations with youth in Harare city, Zimbabwe.
Extracorporeal blood purification in acutely intoxicated veterinary patients: A multicenter retrospective study (2011–2018): 54 cases
Authors: Groover Jennifer , Londoño Leonel A. , Tapia‐Ruano Kristen , Iacovetta Christine
Published: December 2021

Objective

To investigate the clinical outcome and complications associated with extracorporeal blood purification (EBP) using either hemodialysis (HD), hemodialysis and hemoperfusion (HD + HP), or therapeutic plasma exchange (TPE) for the management of acute toxin ingestion in small animals.

Design

Retrospective, multicenter study from January 2011 to July 2018.

Setting

One university teaching hospital and one private specialty hospital.

Animals

Fifty‐one dogs and 3 cats with a history of acute toxin exposure that could lead to severe morbidity and mortality, managed with different EBP techniques.

Main Results

Nonsteroidal anti‐inflammatory drugs (38/54, 52%), baclofen (8/54, 15%), and ethylene glycol (7/54, 13%) were the most common toxicities treated with EBP. Membrane‐based TPE was used most commonly (22/54, 40.7%), followed by HD (17/54, 31.5%) and then HD + HP (15/54, 27.8%). There was an 83.3% (45/54) overall survival, with 88.9% (8/9) of nonsurvivors having clinical signs prior to therapy. One third (18/54) of the patients never developed clinical signs of toxicity. Treatment complications occurred in 44.4% (24/54) of the animals, although only 18.5% (10/54) of these complications, such as mild hypotension, thrombocytopenia secondary to the HP cartridge, facial swelling after plasma transfusion for TPE, bleeding from catheter size secondary to heparinization, or clotting of the system, could be attributed to the EBP treatment. None of the nonsurvivors died because of EBP complications.

Conclusions

Early initiation of EBP therapy might be considered as an alternative route of decontamination in severe acute toxicities with high potential for significant morbidity and mortality. The survival rate in small animals undergoing EBP is high despite exposure to potential lethal doses of toxins, and survival appears to be more likely if clinical signs of toxicity are not present at the time of EBP. Continued research is warranted with randomized controlled clinical trials to further evaluate the clinical efficacy and benefit of EBP.
How Korean K-12 Educators Adapted to Online Teaching and Promoted Digital Equity During COVID-19: A Mixed-Method Study on Practices and Perceptions
Authors: Ko Eunhye Grace , Joo Soo Hyoung , Lim Kyu Yun , Resta Paul E. , Jang Eun Kyoung
Published: December 2021

The abrupt transitions to online teaching during COVID-19 have exacerbated educational discrepancies worldwide. South Korean schools faced similar challenges primarily due to the insufficient infrastructure and pedagogical guidelines for online teaching. This mixed-method case study investigated how Korean K-12 teachers and administrators converted to online teaching and addressed related digital equity issues during their first semester of online teaching in response to the pandemic. Interviews, as well as survey responses at the beginning and end of the semester, were analyzed through Activity Theory (AT) and Technological Pedagogical Content Knowledge (TPACK) frameworks. The study's key insights were that the digital equity issue is related to quality teaching issues beyond infrastructural problems and that teachers took various strategies to maximize the effectiveness of their blended teaching. We aim to shed light on supporting equitable online learning and sustaining positive changes in the post-COVID era.
Middle School Physics Experiment Teaching Within “Internet Plus”: From the Status Quo to Implications
Authors: Chen Yi
Published: December 2021

Middle school physics experiment is a significant basic course with extensive content and strong practicability. This course has high requirements for students to master and understand the background and basic principles of various physical experiments, as well as the working principles and the use of various experimental devices. Based on the importance of physics experiment teaching and the limitations of the traditional experiment teaching mode, this paper first reviews the traditional mode in the context of the Internet and puts forward the new physics experiment teaching mode within "Internet Plus" in the new era, including theoretical guidance of constructing the experimental teaching mode, the innovation of teaching methods and examination methods, and the prospect of promoting the development of education industry. At the same time, this paper puts forward the network teaching platform system that can implement the new physics experiment teaching, including exercises, flipped classroom, and Massive Open Online Courses (MOOC), and discusses them separately, hoping to provide research reference for middle school physics teaching and research in the future.
Experimental Hemodynamics Within the Penn State Fontan Circulatory Assist Device
Authors: Ponnaluri Sailahari V. , Christensen Emma J. , Good Bryan C. , Kubicki Cody J. , Deutsch Steven , Cysyk Joshua P. , Weiss William J. , Manning Keefe B.
Published: December 2021

For children born with a single functional ventricle, the Fontan operation bypasses the right ventricle by forming a four-way total cavopulmonary connection and adapts the existing ventricle for the systemic circulation. However, upon reaching adulthood, many Fontan patients exhibit low cardiac output and elevated venous pressure, eventually requiring a heart transplantation. Despite efforts in developing a new device or using an existing device for failing Fontan support, there is still no Food and Drug Administration-approved device for subpulmonary support. Penn State University is developing a hydrodynamically levitated Fontan circulatory assist device (FCAD) for bridge-to-transplant or destination therapy. The hemodynamics within the FCAD, at both steady and patient averaged pulsatile conditions for three physiological pump operating conditions, were quantified using particle image velocimetry (PIV) to determine the velocity magnitudes and Reynolds normal and shear stresses within the device. Data were acquired at three planes (0 mm and ±25% of the radius) for the inferior and superior vena cavae inlets and the pulmonary artery outlet. The inlets had a blunt velocity profile that became skewed toward the collecting volute as fluid approached the rotor. At the outlet, regardless of the flow condition, a high-velocity jet exited the volute and moved downstream in a helical pattern. Turbulent stresses observed at the volute exit were influenced by the rotor's rotation. Regardless of inlet conditions, the pump demonstrated advantageous behavior for clinical use with a predictable flow field and a low risk of platelet adhesion and hemolysis based on calculated wall shear rates and turbulent stresses, respectively.
Model-Based Control of a Mobile Platform With Independently Controlled In-Wheel Hydraulic Motors
Authors: Hulttinen Lionel , Mattila Jouni
Published: December 2021

Wheeled mobile platforms are important subsystems of heavy-duty working machines, but precise motion control of vehicles with multiple actuated wheels can be challenging, as linear controllers relying solely on velocity feedback could lead to excessive slippage of the wheels in face of varying terrain conditions. When aiming for more advanced control tasks as opposed to path-following, torque control of individual wheels could become necessary in order to distribute the traction effort in a desired fashion between each wheel. Studies on dynamic-model-based control of wheeled mobile robots concentrate on eletrically driven platforms that exhibit more linear behaviour than hydraulic drives, and dynamics of hydraulic motors are rarely addressed in the control design. In this paper, a model-based control design is pursued for a four-wheel vehicle actuated by in-wheel hydraulic motors, all independently controllable by high-bandwidth valves. Experiments on a heavy-duty mobile platform, equipped with wheel odometry, pressure transducers and satellite positioning, are conducted to study the feasibility of the proposed controller.
Pipeline Model Fidelity for Wave Energy System Models
Authors: Simmons Jeremy W. , Van de Ven James D.
Published: December 2021

Ocean wave energy conversion plants that use hydraulic power take-offs (PTOs) have been configured so that the working fluid must travel a significant distance (of several hundred to a few thousand meters) from the wave energy converter (WEC) located offshore to equipment onshore. With the pulsatile flow generated by the WEC having a peak period in the range of 3 to 12 seconds, the wavelengths of the excited pressure waves approach the length of the pipelines themselves. By the standards for modeling pipelines presented in popular fluid power and related textbooks, the system models for these plants should include distributed parameter models of the pipeline dynamics that capture the pressure wave delay effects. This work tests the importance of pipeline model fidelity for wave energy conversion plants. Simulations have been conducted of a simple but representative hydraulic PTO for wave energy conversion and incorporate several common lumped and distributed parameter pipeline models for comparison. These results are used to show the degree to which model fidelity effects several design metrics that are especially useful in the preliminary design phase of system development. The pipeline models used include: 1) a short line model that includes lumped resistive effects only, 2) a medium line model that also includes lumped inertial and capacitive effects for a single pipeline segment, 3) a long line model that uses repeated, lumped parameter line segments to approximate the distributed parameters of a real pipeline, 4) a simple method of characteristics solution to the one-dimensional momentum and continuity equations assuming a fixed wave speed, and 5) a discrete free-gas cavity model augmenting the simple method of characteristic pipeline model. The results suggest a relaxed standard for modeling pipelines in the case of this type of system, in which case, the recommended model is easily implemented in variable time step solvers and CAD software such as Simscape Fluids and can be used within the WEC-Sim modeling framework developed by the National Renewable Energy Lab.
Experimental Validation of Subsystem Models for a Novel Variable Displacement Hydraulic Motor
Authors: Larson Jacob , Pozo-Palacios Jonatan , Boyce-Erickson Grey , Fulbright Nathaniel , Dai Jaichen , Voth John , Gajghate Ninaad , Saikia Jordan , Michael Paul , Chase Thomas , Van de Ven James
Published: December 2021

A novel, variable displacement, low-speed high-torque hydraulic motor is being developed that is expected to be highly efficient across a broad operating range. To ensure the final hardware achieves the expected performance, the models used in the development of the motor must be experimentally validated and revised. The focus of this work is on mechanical energy loss models that were used to guide the design of a single-cylinder motor prototype and then experimental tests used for validation.

Losses were modeled and organized into five primary groups: main shaft bearings, main shaft seal, case windage, valve actuation, and linkage losses. The single-cylinder prototype was fabricated, and test parameters were defined. Two test rigs were designed and built to capture losses of the motor experimentally; one was used to collect low torque, zero/low-pressure differential results, and the other used to collect high torque, high-pressure differential results. A staged assembly procedure was developed to capture the independent contributions of each loss.

By reviewing the quality of correlation between test observations and model predictions and revising the model when necessary, the models were validated. The correlation was improved by reviewing and modifying model inputs. This allows future solutions to be more accurately predicted in the design phase to drive the design of better machines. The validated model package was able to predict the motor performance within an acceptable range of error.
AI-Based Condition Monitoring of Hydraulic Valves in Zonal Hydraulics Using Simulated Electric Motor Signals
Authors: Abdul Azeez Abid , Han Xu , Zakharov Viacheslav , Minav Tatiana
Published: December 2021

Zonal hydraulics, in particular Direct Driven Hydraulics (DDH), is an emerging transmission and actuation technique that is proposed to be used for electrification of heavy-duty mobile machinery. In addition to the already demonstrated advantages of DDH, which include high efficiency, compactness, and ease of maintenance, it is also capable of condition monitoring. The condition monitoring features can be obtained through indirect analysis of the existing electric motor signals (voltage and current) using artificial intelligence-based algorithms rather than by adding extra sensors, which are normally required for conventional realization. In this paper, the valve condition monitoring method of the DDH through electrical motor signals is explored at an early development stage. Firstly, the hydraulic valve models, which involve the valve fault behaviors, are added to the basic DDH model. Secondly, healthy and faulty scenarios for the valves are simulated, and the data are generated. Thirdly, the preliminary artificial intelligence-based condition monitoring classifier is developed using the simulation data, including feature extraction, algorithm training, testing, and comparison of accuracy. The effects of modeling error on developing the condition monitoring function are analyzed. In conclusion, the preliminary outcomes for the valve condition monitoring of the DDH are achieved by taking advantage of modeling and simulation and by utilizing the existing electric motor signals.
Comparative Analysis of Actuator Dimensioning Methods in Pneumatics
Authors: Boyko Vladimir , Hülsmann Steffen , Weber Jürgen
Published: December 2021

In the modern automation technology, there are often two ways to complete a drive task: pneumatically or electrically. In order to remain competitive with the electromechanics and to contribute to the achievement of climate protection goals, manufacturers and users of pneumatic systems are required to increase the energy efficiency of pneumatics. One of the primal and simplest methods to reduce the energy consumption of existing and to-be-developed pneumatic systems is the correct sizing of actuators. However, even in the most modern machines drives are often overdimensioned thus creating a higher energy consumption than necessary.

To counteract this, different dimensioning methods have been developed in the last few years, which could contribute to a significant reduction of energy consumption. Design tools based on dynamic simulations are highly reliable, but their calculation methods can be complex and non-transparent. Therefore, more pragmatic and simple dimensioning methods have been developed, based on algebraic approaches like force equilibrium, exergy equilibrium and pneumatic frequency ratio. In this paper these methods are evaluated using mathematical analysis and practical drive examples. Their possible application fields and limitations are shown and compared.
Dynamic Modeling and Design of a Radial Hydrostatic Piston Pump for Integrated Pump-Motor
Authors: Nahin Md Minal , Bohach Garrett R. , Nishanth F. N. U. , Severson Eric L. , Van de Ven James D.
Published: December 2021

There is a current trend towards the electrification of high force/torque density machines that have traditionally been dominated by diesel engine driven hydraulics. Power dense electric machines tend to favor high operating speeds whereas a hydraulic pump is more efficient at low speed and high torque conditions. The power density of a pump can be increased by decreasing the displacement and increasing the operating speed to provide the flow demand. This miniaturization of the pump allows it to be directly integrated into an electric motor inside a single casing. This integrated pump-motor is free of shaft seals and eliminates a set of bearings otherwise required when coupling an electric motor and pump with a shaft. Additionally, the leakage from the hydraulic pump can be used as coolant for the electrical machine, thereby improving the power density. In this paper, a hydrostatic radial piston pump has been evaluated for integration with an axial flux PM machine. The proposed hydrostatic piston pump uses a spherical head piston that can tilt while reciprocating inside the cylinder, eliminating the need for a joint at the slipper. To reduce the frictional loss between the slipper pad and the cam at high operating speeds, the cam freely rotates. A detailed model of the pump, with focus on the hydrostatic piston slipper, has been developed and a grid search approach has been utilized to select the critical parameters of the pump. Finally, an efficiency map has been presented for this pump at different operating conditions which shows around 86% efficiency at the 12500 rpm speed for 7 MPa pressure differentials.
Double-Input Multi-Output Pressure Control System Based on Addressable Pressure Component
Authors: Wei Qiandiao , Xu He , Chen Siqing , Fan Weiwang
Published: December 2021

Soft robots driven by pressurized fluid have recently been attracted more attention and achieved a variety of innovative applications in bionics, medical surgery, rehabilitation, search, and rescue system. And they have been demonstrated to be able to perform many different tasks, especially in some conditions of demand a high degree of compliance. Generally, they consisted of multiple actuate channels that require independent works. Consequently, a mass of pressure regulators and input pipelines are demanded, which will increase the complexity of the control system. To solve this problem, we propose a new pressure control method inspired by the control bus of electronic interface technology in this paper. An addressable pressure control bus system based on band-pass valve (BPV) and square wave of pressure (control signal) was designed. It consisted of a pressure supply source and an addressing signal, they are controled by two regulators, respectively. One of the pressure pipelines serves as the control bus to transmit the control pressure signal, which plays an addressing signal role in the system. The other serves as the pressure supply source of the multi-channel actuators. The BPV can be set to different opening pressure bands to realize the setting of diverse outputs address codes on the bus. This method discovered the work mode of double-input multi-output, which will get rids of the traditional control method of single-input single-output. In this paper, we designed the BPV and tested its function. To demonstrate the feasibility of this method proposed, a control system with two output ports was established. The result has shown that the output port can be selected by the pressure square wave signal, which realizes the function of single input multiple outputs. It reduces the complexity of the control strategy of the fluid control system.
Nonlinear Cutterhead Pose Control of Large-Diameter Slurry Shields in Complicated Stratum
Authors: Zhang Hangjun , Wei Jianhua , Fang Jinhui , Yang Yuzhu
Published: December 2021

To replace cutterhead worn tools conveniently or get rid of shield’s jamming effectively in complicated stratum, a new nonlinear cutterhead pose control system of large-diameter slurry shields is especially designed. High precision cutterhead pose control of large-diameter slurry shields is hardly achieved due to the uncertain load force and mass. A nonlinear controller constructed by adaptive robust control based on sliding mode is designed for this parallel mechanism, which includes a special adaptation law to compensate for the uncertainties. The stability of the whole closed loop system is verified based on Lyapunov theory. And the validity of the proposed strategy is proved by Simulink and AMESim co-simulation. The simulation results show that not only in control accuracy but also in parameter uncertainty, the designed nonlinear cutterhead pose control is effective.
A Simulation Survey on the Effects of Progressing Faults Within the SCAS of a Flight Control Actuator for Helicopters
Authors: De Martin Andrea , Jacazio Giovanni , Sorli Massimo , Vitrani Giuseppe
Published: December 2021

Stability Control Augmentation Systems (SCAS) are widely adopted to enhance the flight stability of rotary-wing aircraft operating in difficult aerodynamic conditions, such as low altitude missions, stationary flight nearby vertical walls or in presence of heavy gusts. Such systems are based upon small electro-hydraulic servosystems controlled in position through a dedicated servovalve. The SCAS operates with limited authority over the main control linkage translating the pilot input in the movement of the main flight control actuator. Being critical for the operability of the helicopter, the definition of a Prognostics and Health Management (PHM) framework for the SCAS systems would provide significant advantages, such as better risk mitigation, improved availability, and a reduction in the occurrences of unpredicted failures which still represent one of the most known downsides of helicopters. This paper provides the results of a preliminary analysis on the effects of the inception and progression of several degradation types within a simulated SCAS system. Signals usually available within such devices are hence combined with measurements provided by additional sensors to check the feasibility of a PHM system with and without dedicated sensors. The resulting features selection process shows that although the dedicated measurements are required to design a complete PHM system, it appears nonetheless possible to obtain valuable information on the health status of the SCAS system without resorting to additional sensors.
Hydraulic Test Stand to Model Circulatory System Dynamics for Artificial Heart Evaluation
Authors: Howard Joseph T. , Thomas Seth , Gallentine James C. , Barth Eric J.
Published: December 2021

This work proposes the theory and design of an experimental setup to mimic the dynamic impedance of the human circulatory system for testing the dynamic characteristics of an artificial heart. This platform has the same resistance, compliance, and inertance elements as the well-studied 4-element Windkessel model. As opposed to a circuit analogy model commonly seen in the literature, our platform remains within the same energy domain as the circulatory system. This allows an artificial heart designer to test pump performance and dynamic pressure characteristics under realistic loading. A test platform is designed using a non-hazardous working fluid with the same density and viscosity as blood. The system uses as few custom components as possible and interchangeable parts allow for system tuning.
Gold, silver, and copper reference spectra for XPS instruments with monochromatic Ag Lα sources
Authors: Counsell Jonathan D. P. , Shard Alex G. , Cant David J. , Blomfield Christopher J. , Navabpour Parnia , Zhang Xiaoling
Published: December 2021

This article provides calibration spectra for determining the transmission function of an XPS instrument operating with an Ag Lα (2984.3 eV) source monochromated with a quartz (1010) crystal through second order diffraction and irradiating the sample at 54.7° to the surface normal.
In
Mycobacterium abscessus
, the Stringent Factor Rel Regulates Metabolism but Is Not the Only (p)ppGpp Synthase
Authors: Hunt-Serracín Augusto César , Kazi Misha I. , Boll Joseph M. , Boutte Cara C.
Published: December 2021

In this study, we examined the functional roles of the stringent factor Rel in
Mycobacterium abscessus
(
Mab
). In most species, stringent factors synthesize the alarmone (p)ppGpp, which globally alters transcription to promote growth arrest and survival under stress and in antibiotic treatment.