bluuebunny/crossref_metadata_2025 huggingface dataset:
Impacts of Covid‐19 School Closures on School Food Service Revenue: Analysis of Public Local Education Agencies in Maryland
Authors: Zafari Zafar , Cohen Juliana F.W. , Sessom‐Parks Leslie , Lessard Donovan , Cooper Michele , Hager Erin
Published: February 2023

Background

The public health policies and school closures in response to the Covid‐19 pandemic have created disruptions in school meal programs. Research is needed to understand the changes in school food service revenue before and during the initial Covid‐19‐related school shutdowns.

Methods

A longitudinal cohort study examining federal and state reimbursements as well as sales revenues for all public local education agencies (LEAs) in Maryland from school years (SY) 2018‐2019 and 2019‐2020 was conducted. Monthly changes in federal and state reimbursements for Child Nutrition Programs, including the National School Lunch Program (NSLP), School Breakfast Program (SBP), Summer Food Service Program (SFSP), and Child and Adult Care Food Program (CACFP) were examined.

Results

In the SY 2018‐2019, the total revenues from federal and state reimbursements for SBP, NSLP, SFSP, and at‐risk CACFP were $272.9 million; in comparison, for the SY 2019‐2020, the total revenues were $241.8 million (11.4% reduction from SY 2018‐2019). On average, the school shutdown (during March to June 2020) was associated with a $450,385 (p‐value < .01) reduction in federal and state reimbursements per LEA‐month (41% reduction).

Conclusions

The school shutdown during the Covid‐19 pandemic was associated with a statistically significant reduction in school food service revenues across Maryland's public LEAs.
Prenatal substance use in the rural and Appalachian state: Project WATCH study 2020‐2022
Authors: Umer Amna , Garrow Jana , Nesbitt Makena , Lilly Christa , Lefeber Candice , Breyel Janine , John Collin
Published: February 2023

Purpose

To examine the prevalence, patterns, and correlates of prenatal substance use in the rural Appalachian state of West Virginia (WV).

Methods

Population‐based cohort (Project WATCH) of all women (N = 34,309) who gave birth between February 2020 and June 2022. A composite substance use variable included 9 categories: “no substance use,” “opioids,” “cannabis,” “sedatives/hypnotics,” “stimulants,” “opioids and cannabis,” “opioids and stimulants,” “cannabis and stimulants,” and “opioids, cannabis, and stimulants.” These data were gathered through self‐report, medical records, and/or positive drug screen at labor and delivery.

Findings

12.4% of women used one or more substances (opioids, cannabis, stimulants, and sedatives/hypnotics) during their current pregnancy. The mean age of women using cannabis was 25.34 (SD = 5.31), stimulants was 28.88 (SD = 5.62), and opioid was 30.19 (SD = 4.78). White women were more likely to use opioids (aOR = 2.19, 95% CI 1.46, 3.28) and less likely to use cannabis (aOR = 0.39, 95% CI 0.34, 0.44) compared to minority racial groups. Women with cannabis use were more likely to live in urban versus rural regions (aOR = 1.47, 95% CI 1.33, 1.62). The odds of using any type of substance(s) were significantly higher in women who smoked (aOR range 4.17‐30.85), had Medicaid (aOR range 1.52‐7.65), and those receiving inadequate prenatal care (aOR range 1.96‐16.83).

Conclusions

In this rural Appalachian state, 1 in 8 women used 1 or more substances (opioids, cannabis, stimulants, and/or sedatives/hypnotics) during pregnancy and the type of substance used varied by sociodemographic and health‐related factors. These factors should inform state‐level strategies and initiatives to address the substance use crisis for this population.
Long‐term outcome of liver transplantation for autoimmune hepatitis: A French nationwide study over 30 years
Authors: Chouik Yasmina , Chazouillères Olivier , Francoz Claire , De Martin Eleonora , Guillaud Olivier , Abergel Armand , Altieri Mario , Barbier Louise , Besch Camille , Conti Filomena , Corpechot Christophe , Dharancy Sébastien , Durand François , Duvoux Christophe , Gugenheim Jean , Hardwigsen Jean , Hilleret Marie‐Noëlle , Houssel‐Debry Pauline , Kamar Nassim , Maucort‐Boulch Delphine , Minello Anne , Neau‐Cransac Martine , Pageaux Georges‐Philippe , Radenne Sylvie , Roux Olivier , Saliba Faouzi , Serée Olivier , Samuel Didier , Vanlemmens Claire , Woehl‐Jaegle Marie‐Lorraine , Leroy Vincent , Duclos‐Vallée Jean‐Charles , Dumortier Jérôme
Published: February 2023

Background & Aims

Autoimmune hepatitis (AIH) is a rare indication for liver transplantation (LT). The aims of this study were to evaluate long‐term survival after LT for AIH and prognostic factors, especially the impact of recurrent AIH (rAIH).

Methods

A multicentre retrospective nationwide study including all patients aged ≥16 transplanted for AIH in France was conducted. Early deaths and retransplantations (≤6 months) were excluded.

Results

The study population consisted of 301 patients transplanted from 1987 to 2018. Median age at LT was 43 years (IQR, 29.4–53.8). Median follow‐up was 87.0 months (IQR, 43.5–168.0). Seventy‐four patients (24.6%) developed rAIH. Graft survival was 91%, 79%, 65% at 1, 10 and 20 years respectively. Patient survival was 94%, 84% and 74% at 1, 10 and 20 years respectively. From multivariate Cox regression, factors significantly associated with poorer patient survival were patient age ≥58 years (HR = 2.9; 95% CI, 1.4–6.2; p = 0.005) and occurrence of an infectious episode within the first year after LT (HR = 2.5; 95% CI, 1.2–5.1; p = 0.018). Risk factors for impaired graft survival were: occurrence of rAIH (HR = 2.7; 95% CI, 1.5–5.0; p = 0.001), chronic rejection (HR = 2.9; 95% CI, 1.4–6.1; p = 0.005), biliary (HR = 2.0; 95% CI, 1.2–3.4; p = 0.009), vascular (HR = 1.8; 95% CI, 1.0–3.1; p = 0.044) and early septic (HR = 2.1; 95% CI, 1.2–3.5; p = 0.006) complications.

Conclusion

Our results confirm that survival after LT for AIH is excellent. Disease recurrence and chronic rejection reduce graft survival. The occurrence of an infectious complication during the first year post‐LT identifies at‐risk patients for graft loss and death.
“Where Do I Even Start?”: Exploring Resources for Anthropology Students’ College‐to‐Career Transitions
Authors: Ding Emily , Storey Angela D. , Lee Brianna M. , Jhoslien Anastasia , Cora Maria
Published: February 2023

This article explores the resources that are available, or should be made available, to support college‐to‐career transitions for undergraduate anthropology students. Using mixed methods, this research was conducted by undergraduate anthropology students at a small Christian college in Illinois and at a large public university in Kentucky, in conjunction with a wider project for the American Anthropological Association. Based on our two case studies, we argue that students, faculty, and career centers often do not effectively work together to provide and utilize career resources for anthropology majors. This lack of collaboration leads to students feeling underresourced and undersupported. This is partially due to student disinclination to use career center resources but also a result of the way career centers present themselves to students and faculty's inattention toward facilitating a connection between them. We end with recommendations for departments, career centers, and students to facilitate resource availability and use.
Evolution of depressive symptoms from before to 24 months after bariatric surgery: A systematic review and meta‐analysis
Authors: Woods Robbie , Moga Ana M. , Ribeiro Paula A. B. , Stojanovic Jovana , Lavoie Kim L. , Bacon Simon L.
Published: February 2023

Aims

Depression after bariatric surgery can lead to suboptimal health outcomes. However, it is unclear how depressive symptoms evolve over the 24 months after surgery. We determined the extent depressive symptoms changed up to 24 months after bariatric surgery and how this was impacted by measurement tool and surgical procedure.

Methods

We conducted a systematic review and meta‐analysis, searching five databases from database inception to June 2021 for studies that prospectively measured depressive symptoms before and up to 24 months after bariatric surgery. Change scores were converted to Hedge's g, and analyses were performed using mixed‐effects models. Subgroup analyses examined differences across time of follow‐up, measurement tool, and surgical procedure.

Findings

Forty‐six studies met inclusion criteria (32,342 patients). Meta‐analysis indicated a postsurgical reduction in depressive symptom scores that were significant (large effect, g = 0.804; 95% CI: 0.73–0.88, I2 = 95.7%). Subgroup analyses found that symptom reductions did not differ between the timing of follow‐up periods, measurement tool, and surgical procedure.

Conclusions

Depressive symptom scores reduced substantially following surgery; comparable decreases occurred 6 through 24 months after surgery. These findings can help inform practitioners of the typical evolution of depressive symptoms following surgery and where deviations from this may require additional intervention.
Potential effects of anticoagulants in preclinical mice models of oral cancer: A systematic review
Authors: Al‐Azzawi Huda Moutaz Asmael , Hamza Syed Ameer , Lin Zichen , Paolini Rita , McCullough Michael , Yap Tami , Celentano Antonio
Published: February 2023

Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer. There is mounting evidence to suggest that several components of the coagulation system directly affect carcinogenesis. Our recent in vitro studies demonstrated, for the first time, that various anticoagulants have anticancer effects on OSCC. They also showed the need for the immediate translation of these experimental conditions from bench to preclinical animal models. Here, we carried out a systematic review to summarise existing evidence on murine models built around the interactions between anticoagulants and oral cancer. Only one preclinical murine study was included in our systematic review, investigating the role of heparins in tumour pathophysiology. The paucity of evidence regarding the interactions between oral squamous cell carcinoma and anticoagulants emphasises the urgency with which further preclinical research should be conducted.
The therapeutic perspective of cold atmospheric plasma in periodontal disease
Authors: Liu Zhixin , Du Xijin , Xu Lianyi , Shi Qi , Tang Xuezhi , Cao Yingguang , Song Ke
Published: February 2023

Objectives

Periodontal disease (PD) is one of the most common infectious diseases with complex inflammatory conditions, having irreversibly destructive impacts on the periodontal supporting tissues. The application of cold atmospheric plasma (CAP) is a promising adjuvant therapy modality for PD. However, the mechanism of CAP in PD treatment is still poorly understood. The review motivates to outline the latest researches concerning the applications of CAP in PD treatment.

Methods

We searched CAP‐related literature through utilizing the well‐established databases of Pubmed, Scopus and Web of Science according to the following keywords related to periodontal disease (periodontal, gingival, gingivitis, gingiva, periodontium, periodontitis).

Results

A total of 18 concerning original studies were found. These studies could be classified according to three pathophysiological perspectives of PD. The therapeutic mechanisms of CAP may be attributed to the oxidative stress‐related cell death of periodontal bacteria, the suppression of periodontal inflammation and pro‐inflammatory cytokine secretion, as well as the acceleration of periodontal soft tissue wound healing and hard tissue reconstruction.

Conclusions

Cold atmospheric plasma has potential therapeutic effects on PD through three mechanisms: antimicrobial effect, inflammation attenuation, and tissue remodeling. This review hopefully provides a comprehensive perspective into the potential of CAP in PD therapy.
Modulating Photochemical Properties to Enhance the Stability of Electronically Dimmable Eye Protection Devices†
Authors: Baburaj Sruthy , Parthiban Jayachandran , Rakhimov Sarvar Aminovich , Johnson Rasheedah , Sukhomlinova Ludmila , Luchette Paul , Jockusch Steffen , Forbes Malcolm D. E. , Sivaguru Jayaraman
Published: February 2023

The study evaluates compatibility of stabilizers with dye doped liquid crystal (LC) scaffolds that are used in electronically dimmable materials. The photodegradation of the materials was investigated and suitable stabilizers were evaluated to slow the degradation process. Various types of benzotriazole‐based stabilizers were evaluated for stabilizing the liquid crystals. Based on spin trapping experiments, radicals generated upon UV exposure is likely responsible for the degradation of the system. The radical generation is competitively inhibited by the addition of stabilizers.
New Measures for Family Planning and Exposure to Risk of Pregnancy Based on Sexual Activity and Contraceptive Use Data
Authors: Lee Chi Hyun , Susmann Herbert , Alkema Leontine
Published: February 2023

Family planning measures for unmarried women are based on contraceptive demand and use among sexually active women. Sexual activity status is commonly defined based on comparing reported time‐since‐last‐sex to a cutoff time, with women defined to be sexually active if their most recent sex was within the last four weeks. While easy to understand and compute, this approach to constructing family planning measures results in a limited understanding of family planning and exposure to unintended pregnancy because it cannot comprehensively capture the frequency of sex at the population level. We propose a new statistical approach to quantify sexual activity, using reported time‐since‐last‐sex data. Based on estimated frequencies of sex among users and nonusers in need of family planning, we propose new family planning measures, including the ratio of protected exposure over all women's exposure to risk of unintended pregnancy.
Healthcare resource utilization prior to suicide death or suicide attempt in patients with major depressive disorder—A Danish registry‐based cohort study
Authors: Jensen Kristoffer Jarlov , Osler Merete , Bødker Nikolaj , Riise Jesper , Petersen Janne
Published: February 2023

Introduction

Major depressive disorder (MDD) is associated with suicide events and with increased healthcare resource utilization (HRU). The aim was to analyze the pattern of HRU prior to death by suicide or suicide attempt in patients with MDD using national registries.

Methods

Danish adults with MDD, who died by suicide or had a first‐time suicide attempt, were matched with MDD controls on age, sex, and MDD severity and analyzed for psychiatric and non‐psychiatric hospital and private practitioner contacts, and prescriptions 1 year prior to the event. For individuals having a second suicide attempt, HRU prior to first and second suicide attempt was analyzed.

Results

Among 1061 individuals dying by suicide and 3759 individuals with suicide attempt, compared with their controls, the proportion with psychiatric hospitalization was more than 50% increased, mainly accounted for by acute contacts. The difference to the matched controls decreased with increasing MDD severity. Non‐psychiatric HRU was increased as well. The proportion with psychiatric hospitalizations or ED visits was reduced prior to the second attempt compared with first attempt.

Conclusion

Among individuals with MDD, psychiatric and non‐psychiatric HRU was increased 1 year prior to suicide event. The proportion of individuals who had psychiatric HRU decreased from first to second suicide attempt.
Structural changes in humic substances after long‐term fertilization of a calcareous soil with pig slurries
Authors: Jiménez‐de‐Santiago Diana E. , Almendros Gonzalo , Bosch‐Serra Àngela D.
Published: February 2023

Pig slurries are widely used on calcareous soils in European rainfed systems. Here we assess their impact on the amount of soil organic carbon (SOC) and on the composition of humic‐type substances (HTS). Seven doses of slurry (five from fattening pigs and two from sows) ranging from 1.0 to 4.8 Mg ha−1 yr−1 of organic matter were evaluated after a period of 12 years and compared with mineral fertilizer treatment. At the end of the last annual cropping season (September), SOC was quantified, and HTS were isolated by alkaline extraction followed by acid precipitation, and studied by visible spectroscopy (800–400 nm) and Fourier‐transformed infrared spectroscopy (4000–400 cm−1). Following the trend in the slurry organic matter applied rates, SOC increased from 9.5 g C kg−1 (mineral treatment) to 13.8 g C kg−1. This SOC increase was equivalent to c. 25.4% of the slurry organic carbon applied. The incorporation of aliphatic structures, mainly polyalkyl, from slurries into the HTS tends to modify the composition of the soil organic matter (SOM), which is reflected in a decrease in the intensity of FT‐IR peaks related to aromatic structures. Despite the trend of significant increase in SOC with fattening slurries, mainly from the organic matter rate of 1.6 Mg ha−1 yr−1 (c. 185 kg N ha−1), the composition of the HTS showed an important aliphatic enhancement. The FTIR results showed that using exclusively the relative intensities of specific peaks (alkyl, carboxyl, aromatic and amide groups) as variables for the discriminant analysis, it is possible to identify HA between different groups of soils treated with progressive levels of slurry. Although the new aliphatic components could be considered important to improve soil physical quality, after the incorporation of additional SOM, the spectroscopic characteristics of HTS in soils treated with slurries suggested a weak effect in long‐term C sequestration, as the newly incorporated OC forms are not qualitatively similar to the presumably stable native SOM. These potential changes in SOC and SOM composition at field level are constrained by the maximum allowed N rates from organic origin in some agricultural systems.
Distributions of HLA‐A, ‐B, ‐C, ‐DRB1 and ‐DQB1 alleles typed by next generation sequencing in Russian volunteer donors
Authors: Smirnova Daria , Loginova Maria , Druzhinina Svetlana , Paramonov Igor , Abramova Anna , Simakova Tamara
Published: February 2023

HLA genes play a major role for successful hematopoietic stem cell transplantation (HSCT). While the success of HSCT depends on a HLA compatibility between donor and patient, finding a suitable donor remains challenging because of the high polymorphic nature of HLA genes. In this study, HLA‐A, ‐B, ‐C, ‐DRB1 and ‐DQB1 alleles were genotyped at the 3‐fields resolution level using MiSeq Illumina of 3341 Russian volunteers from the Kirov bone marrow Registry. Full gene of HLA‐A, ‐B and ‐C, exons 2–4 of HLA‐DRB1 and exons 1–5 of HLA‐DQB1 were amplified by multiplex long‐range polymerase chain reaction (PCR) and each allele was determined by matching the targeted regions and the reference sequence consisting of the IPD‐IMGT/HLA Database. A total of 79 alleles of HLA‐A, 115 alleles of HLA‐B, 67 alleles of HLA‐C, 71 alleles of HLA‐DRB1 and 34 alleles of HLA‐DQB1 were identified. According to common, intermediate and well‐documented catalogs, 38 alleles in HLA‐A, 69 in HLA‐B, 39 in HLA‐C, 48 in HLA‐DRB1 and 21 in HLA‐DQB1 locus were common alleles, and 5, 7, 7, 7, 2 kinds, accordingly, to written above were well‐documented alleles. A total of 12 novel alleles including 3 alleles in HLA‐A, 3 alleles in HLA‐B, 1 allele in HLA‐C, 2 alleles in HLA‐DRB1 and 3 alleles in HLA‐DQB1 loci were found. Six haplotypes with a frequency of more than 1.0% accounted for 13.19% of the total haplotype frequencies. This information on rare and novel alleles found by HLA typing with NGS may be helpful for unrelated HSCT among Russians.
Enumeration of regular maps of given type on twisted linear fractional groups
Authors: Mačaj Martin , Pavlíková Soňa , Širáň Jozef
Published: February 2023

We enumerate orientably regular maps of any given type with automorphism group isomorphic to a twisted linear fractional group; these groups form the ‘other’ family in Zassenhaus' classification of finite sharply 3‐transitive groups.
Realising sets of integers as mapping degree sets
Authors: Neofytidis Christoforos , Wang Shicheng , Wang Zhongzi
Published: February 2023

Given two closed oriented manifolds of the same dimension, we denote the set of degrees of maps from to by . The set always contains zero. We show the following (non‐)realisability results.

There exists an infinite subset of containing 0 which cannot be realised as , for any closed oriented ‐manifolds .

Every finite arithmetic progression of integers containing 0 can be realised as , for some closed oriented 3‐manifolds .

Together with 0, every finite geometric progression of positive integers starting from 1 can be realised as , for some closed oriented manifolds .
Knee movements cause changes in the firing behaviour of muscle spindles located within the mono‐articular ankle extensor soleus in the rat
Authors: Maas Huub , Noort Wendy
Published: February 2023

We recently showed that within an intact muscle compartment, changing the length of one muscle affects the firing behaviour of muscle spindles located within a neighbouring muscle. The conditions tested, however, involved muscle lengths and relative positions that were beyond physiological ranges. The aim of the present study was to investigate the effects of simulated knee movements on the firing behaviour of muscle spindles located within rat soleus (SO) muscle. Firing from single muscle spindle afferents in SO was measured intra‐axonally for different lengths (static) and during lengthening (dynamic) of the lateral gastrocnemius and plantaris muscles. Also, the location of the spindle within the muscle was assessed. Changing the length of synergistic ankle plantar flexors (simulating different static knee positions, between 45 and 130°) affected the force threshold, but not the length threshold, of SO muscle spindles. The effects on type II afferents were substantially (four times) higher than those on type IA afferents. Triangular stretch–shortening of synergistic muscles (simulating dynamic knee joint rotations of 15°) caused sudden changes in the firing rate of SO type IA and II afferents. Lengthening decreased and shortening increased the firing rate, independent of spindle location. This supports our prediction that the major point of application of forces exerted by connections between adjacent muscles is at the distal end of SO. We conclude that muscle spindles provide the CNS with information about the condition of adjacent joints that the muscle does not span.
Robust Design Optimization of Expensive Stochastic Simulators Under Lack-of-Knowledge
Authors: van Mierlo Conradus , Persoons Augustin , Faes Matthias G. R. , Moens David
Published: February 2023

Robust design optimization of stochastic black-box functions is a challenging task in engineering practice. Crashworthiness optimization qualifies as such problem especially with regards to the high computational costs. Moreover, in early design phases, there may be significant uncertainty about the numerical model parameters. Therefore, this paper proposes an adaptive surrogate-based strategy for robust design optimization of noise-contaminated models under lack-of-knowledge uncertainty. This approach is a significant extension to the robustness under lack-of-knowledge method (RULOK) previously introduced by the authors, which was limited to noise-free models. In this work, it is proposed to use a Gaussian Process as a regression model based on a noisy kernel. The learning process is adapted to account for noise variance either imposed and known or empirically learned as part of the learning process. The method is demonstrated on three analytical benchmarks and one engineering crashworthiness optimization problem. In the case studies, multiple ways of determining the noise kernel are investigated: (1) based on a coefficient of variation, (2) calibration in the Gaussian Process model, (3) based on engineering judgment, including a study of the sensitivity of the result with respect to these parameters. The results highlight that the proposed method is able to efficiently identify a robust design point even with extremely limited or biased prior knowledge about the noise.
Investigation of Mechanical Behaviors of Dental Implants With Different Geometries
Authors: Yuan Zhongxiao , Chong Perk Lin , Roy Sandipan , Merdji Ali , Ouldyerou Abdelhak , Faraji Foad , Moey Lip Kean , Yazdi Mohammad Hossein , Mukdadi Osama M.
Published: February 2023

Dental implants have received a lot of attention and have been used to treat symptoms such as missing teeth and bad teeth. Due to the wide range of occupations and ages of patients, the functions and aims of implants are different. There are many kinds of dental implant shapes. However, with the popularity of dental implants, the problems caused by the some of the dental implant shapes have received much attention. In fact, some implants were used incorrectly. This makes the stress distribution around the implant unreasonable; it not only affects the surrounding bone resorption but also causes mechanical fracture of the implant. This work aims to evaluate the mechanical features of five different kinds of dental implant systems. By applying engineering systems of investigations such as FEM, five types of dental implants and surrounding bone tissue were modeled and simulated under vertical loads of 90 N. Distributions of stresses and deformations in the bone were obtained and ranked according to statistical scores, which were used to judge the optimum geometry of implants. The analytical results showed that the cylindrical implant is the most optimum shape among the other types of implants.
Unconditionally Stable Numerical Scheme for Heat Transfer of Mixed Convective Darcy–Forchheimer Flow of Micropolar Fluid Over Oscillatory Moving Sheet
Authors: Nawaz Yasir , Arif Muhammad Shoaib , Abodayeh Kamaleldin
Published: February 2023

This contribution proposes a third-order numerical scheme for solving time-dependent partial differential equations (PDEs). This third-order scheme is further modified, and the new scheme is obtained with second-order accuracy in time and is unconditionally stable. The unconditional stability of the new scheme is proved by employing von Neumann stability analysis. For spatial discretization, a compact fourth-order accurate scheme is adopted. Moreover, a mathematical model for heat transfer of Darcy–Forchheimer flow of micropolar fluid is modified with an oscillatory sheet, nonlinear mixed convection, thermal radiation, and viscous dissipation. Later on, the dimensionless model is solved by the proposed second-order scheme. The results show that velocity and angular velocity have dual behaviors by incrementing coupling parameters. The proposed second-order accurate in-time scheme is compared with an existing Crank–Nicolson scheme and backward in-time and central in space (BTCS) scheme. The proposed scheme is shown to have faster convergence than the existing Crank–Nicolson scheme with the same order of accuracy in time and space. Also, the proposed scheme produces better order of convergence than an existing Crank–Nicolson scheme.
Investigation of Tip Leakage Vortex Breakdown in a High-Speed Multistage Axial Compressor
Authors: Seki Ryosuke , Azuma Toshihiko , Iwatani Junji , Nakaniwa Akihiro , Okui Hidetaka , Shibata Takanori
Published: February 2023

In this article, an unsteady tip leakage flow instability is identified and investigated for an axial compressor at near-surge conditions. We describe the results of experimental verification of a new compressor developed by improving the blade geometry based on the criterion for the occurrence of this unsteady phenomenon. In a high-speed multistage axial flow compressor having a subsonic high stagger rotor blade, a surge test was carried out by changing the tip clearance. Under a condition of large tip clearance, a drastic decrease in the static pressure rise coefficient near the surge point was observed. At this operating condition, large, unsteady pressure fluctuation at the blade tip was confirmed, and the occurrence of tip leakage vortex breakdown was clarified by unsteady multipoint pressure measurement and detailed unsteady numerical simulations. Due to the blockage effect caused by vortex breakdown of the tip leakage, double leakage and axially reversed flow near the trailing edge were observed. It was found that the vortex breakdown region of the tip leakage vortex propagated in the circumferential direction and caused the rotating instability. In order to investigate the relationship among this unsteady flow phenomenon, tip clearance size, and flow pattern, unsteady calculation was conducted by changing the blade tip stagger and tip clearance size. A new concept of tip clearance of staggered pitch reference was proposed, which makes it possible to include the effect of blade loading on the clearance and clarifies that there exists a threshold at which vortex breakdown occurs/does not occur. On the basis of the aforementioned results, a high-speed multistage improved compressor was designed and manufactured to prevent tip leakage vortex breakdown. A clearance change test using active clearance control technology was conducted, and an increase in the static pressure rise coefficient near the surge point was confirmed for each clearance. The design concept of the improved blade, which suppressed the unsteady tip leakage flow instability, was tested and verified, and the effectiveness of the design guideline in actual gas turbines for power generation was confirmed.
Blade Vibration Analysis for Radial Turbine Featuring a Multi-Channel Casing Design
Authors: Hassan Ahmed Farid Ayad , Müller Fabian F. , Schatz Markus , Vogt Damian M.
Published: February 2023

Multi-channel casing (MC) shows promising results in controlling the performance of the radial turbines. It has neither movable parts nor complicated control mechanisms therefore it withstands higher thermal loads compared to the commonly used control systems such as the Variable Geometry Turbine (VGT). This advantage makes the MC applicable for a wider range of applications which is difficult to be covered with the common control systems. Replacing the traditional spiral casing with the MC affects the blade's vibration behavior. First, a 3D unsteady computational fluid dynamic (CFD) simulation is performed to investigate the influence of using MC on the turbine flow field for both full and partial admission operation. Second, a forced response analysis is performed based on the CFD result to calculate the blade vibration amplitude at different resonance crossings. Finally, an MC is manufactured and tested experimentally to validate the numerical study. The results show that ignoring the casing replacement effect on the blade vibration during the MC design phase led to a high vibration amplitude and consequently causes high cycle fatigue.
Machine-Learning-Based Hydraulic Fracturing Flowback Forecasting
Authors: Guo Jinyuan , Guo Wei , Kang Lixia , Zhang Xiaowei , Gao Jinliang , Liu Yuyang , Liu Ji , Yu Haiqing
Published: February 2023

Hydraulic fracturing is an indispensable procedure to the economic development of shale gas. The flowback of the hydraulic fracturing fluid is one of the most important parameters recorded after shale gas wells are put into production. Generally, the flowback ratio is used as the flowback indicator during hydraulic fracturing. The flowback ratio has a great influence on shale gas production. However, the flowback ratio is subjected to various affecting factors with their correlativity unclear. Based on a large amount of original geological, engineering, and dynamic data acquired from 373 hydraulically fractured horizontal wells, the flowback characteristics were systematically studied based on machine learning. Based on the data analysis and random forest forecasting, a new indicator, single-cluster flowback ratio, was proposed, which can more effectively reflect the inherent relationship between flowback fluid volume and influencing factors. The results of training random forests for big data show that this indicator has better learnability and predictability. A good linear relationship exists between single-cluster flowback ratios in different production stages. Accordingly, the 30-day single-cluster flowback ratio can be used to predict the 90-day and 180-day single-cluster flowback ratios. The main controlling factors of production and flowback ratio were also systematically analyzed. It is found that the main controlling factors of the flowback ratio include the number of fracturing clusters, the total amount of sand, number of fracturing stages, and fluid injection intensity per cluster. This study can provide a fundamental reference for analyzing the hydraulically fracturing fluid flowback for shale gas reservoirs.
An Efficient Decoupled Reliability-Based Topology Optimization Method Based on a Performance Shift Strategy
Authors: Zheng Jing , Yuan Liang , Jiang Chao , Zhang Zhe
Published: February 2023

In this paper, a new efficient reliability-based topology optimization (RBTO) method is proposed for structures, in which the double-loop optimization is equivalently decoupled into a sequential process based on a performance shift strategy. First, a volume minimization RBTO formulation is built for structures considering displacement or compliance reliability constraints. Second, an efficient decoupling scheme is proposed to turn the double-loop RBTO into a series of deterministic topology optimization and reliability analysis. For the reliability analysis, the reliability probability is calculated based on the probability distribution function of the performance function, and the probability distribution function can be solved by the maximum entropy method based on the raw moments calculated by the multiplicative dimension reduction method. A performance shift strategy is then applied to build an equivalence between probabilistic constraint and deterministic constraint to formulate the deterministic topology optimization. Thirdly, the adjoint variable method is applied to obtain the sensitivity information for topological design variables, and a gradient-based optimization algorithm is used to update the design variables. Finally, four typical numerical examples are used to verify the advantage of the proposed method. Compared with the traditional sequential optimization and reliability assessment (SORA) method, the proposed RBTO method results in a design with a 5.4% smaller volume value to reach the same reliability index requirement for the cantilever beam, and the function calls are 354 times less than that of the SORA method.
A Novel Method to Design Translational Parallel Manipulators With an Assigned Maximum Orientation Error
Authors: Di Gregorio Raffaele , Simas Henrique , Simoni Roberto
Published: February 2023

Geometric Design and Tolerancing (GD&T) is the language that specifies several design features and, in this paper, is used to deal with the tolerances of Translational Parallel Manipulators (TPMs). TPMs intend to make a platform have only translational motion with respect to the frame (base), but, in practice, TPMs’ platforms present undesirable rotation motions due to unavoidable geometric errors in links’ sizes. During the machine-element design, geometric errors can be limited by imposing given tolerances on links’ sizes and the tighter tolerances are the higher manufacturing costs are. Therefore, dealing with tolerances is the key for designing a TPM with assigned requirements in terms of platform’s rotation limits. In this context, this paper moves from the fact that machining processes generate link sizes with values distributed according to Gaussian distributions, whose mean values are the nominal sizes and whose standard deviations depend on the machining process accuracy, to build a novel method that makes a designer able to satisfy an assigned maximum orientation error on the TPM platform. The proposed method consists of two main phases: (a) identification of the geometric parameters that affect platform’s position and orientation, and (b) an analysis, based on numerical simulations, that relates the tolerances assigned to the identified parameters and the positioning precision of the platform. The method can be adapted to other types of lower-mobility robots (LMRs). A case study is also discussed to better illustrate the method.
Jerk-Optimal Piecewise Planning of Tool Orientation for 5-Axis Ball-End Machining With Linearized Kinematic Constraints
Authors: Wu Lei , Xu Jinting , Yin Xiaolong , Sun Yuwen
Published: February 2023

When planning tool orientations for 5-axis machining from the perspective of kinematics, existing works often tend to optimize the angular velocity or acceleration of the rotary axes rather than the angular jerk due to its calculation sensitivity to discretization variations, though the jerk is fundamentally tied to the tracking errors and residual vibrations of the actuators. In this paper, a study is reported on how to optimize the angular jerk of the rotary axes while comprehensively considering the kinematic constraints, thus achieving a jerk-optimal tool orientation along the tool path, with driving capacity of the rotary axes respected. In this method, the displacements of the rotary axes are continuously represented by two quintic B-spline curves, and then the angular velocity, acceleration, and jerk of the rotary axes, which are the derivatives of the displacements, can be succinctly represented as a B-spline curve. Taking advantage of the convex hull property of B-spline curve, the linear analytical representations of the kinematic constraints of the rotary axes can be successfully derived in form of control coefficient combinations. To prevent the machining interference at the same time, a greedy strategy that incorporates a process of alternately smoothing tool orientation and checking machining interference is employed. Then, the smooth displacement splines of the rotary axes can be obtained by solving a constructed quadratic programming (QP) model that minimizes the angular jerk along the tool path, while satisfying kinematic constraints and without machining interference. Moreover, to generate efficiently tool orientations for long tool paths, a piecewise planning strategy that optimizes the tool orientation from coarse to fine is developed. Finally, the conducted experiments validate the proposed method.
A Hybrid Deep Generative Network for Pore Morphology Prediction in Metal Additive Manufacturing
Authors: Song Zheren , Wang Xinming , Gao Yuanyuan , Son Junbo , Wu Jianguo
Published: February 2023

Metal additive manufacturing (AM) has been receiving unprecedented attention for its transformational role in extending the AM materials from polymers to various metals. However, various quality issues, especially porosity, significantly impacts the mechanical properties and fatigue life of the final products, which imposes barriers for the widespread adoption of metal AM processes. In this study, we use the deep learning (DL) techniques to comprehensively investigate the relationships between pore microstructure and processing parameters. Specifically, a novel hybrid deep generative prediction network (HDGPN) that leverages both variational autoencoder and generative adversarial network is proposed to characterize the complex pore microstructure with in-depth representations and predict pore morphology under arbitrary processing parameters. By visualizing the predicted pore morphology, the complicated interaction dynamics between the processing parameters and pore microstructure are directly revealed, which may guide the optimization of metal AM manufacturing processes to fabricate defect-free products. A case study of a selective laser melting (SLM) process is conducted to validate the proposed modeling and prediction framework.
Computing zero-group-velocity points in anisotropic elastic waveguides: Globally and locally convergent methods
Authors: Kiefer Daniel A. , Plestenjak Bor , Gravenkamp Hauke , Prada Claire
Published: February 2023

Dispersion curves of elastic waveguides exhibit points where the group velocity vanishes while the wavenumber remains finite. These are the so-called zero-group-velocity (ZGV) points. As the elastodynamic energy at these points remains confined close to the source, they are of practical interest for nondestructive testing and quantitative characterization of structures. These applications rely on the correct prediction of the ZGV points. In this contribution, we first model the ZGV resonances in anisotropic plates based on the appearance of an additional modal solution. The resulting governing equation is interpreted as a two-parameter eigenvalue problem. Subsequently, we present three complementary numerical procedures capable of computing ZGV points in arbitrary nondissipative elastic waveguides in the conventional sense that their axial power flux vanishes. The first method is globally convergent and guarantees to find all ZGV points but can only be used for small problems. The second procedure is a very fast, generally-applicable, Newton-type iteration that is locally convergent and requires initial guesses. The third method combines both kinds of approaches and yields a procedure that is applicable to large problems, does not require initial guesses and is likely to find all ZGV points. The algorithms are implemented in GEW ZGV computation (doi: 10.5281/zenodo.7537442).
An Integrated Mind–Body Training Intervention on an Elite Surfing Athlete: A Case Study
Authors: Takeuchi Eduardo , Lacerda Shirley S. , Brech Guilherme Carlos , Kozasa Elisa H.
Published: February 2023

The aim of this case study was to evaluate the effects of integrated mind–body training in an elite surfing athlete. The mental training included the development of mental techniques (self-talk/internal monologue and mental imagery), mental skills (emotional regulation, state of presence, self-awareness, self-control, and self-confidence), life and performance coaching sessions (behavior improvement), and meditation and breathing techniques. The physical training consisted of “educating a conscious athlete” (he knows what he needs to do and why he is doing it); increasing muscles; perfecting the joint functions; developing physical capabilities of power, strength, and speed endurance; and exploring the same behaviors and mental skills integrated in the mind training. The athlete had his best classifications after the beginning of the intervention: third place in the Championship Tour in 2018, fourth place in 2019, second in 2021, and first in 2022, without any injuries, suspensions, or 25th-place classification in a surfing competition (the worst possible classification, which had happened in all previous years). Improvement in his behavior and lifestyle also helped the athlete realize his dreams. The result suggests that mind–body training might have contributed to his improvement and stability in the years 2018–2022.
Constellation Mentoring for University Soccer Players: A Case Study
Authors: Petersen Brennan , Giffin Cole E. , Middleton Thierry R.F. , Li Yufeng
Published: February 2023

Peer mentoring is a supportive relationship between a more experienced mentor and a less experienced protégé that has garnered attention in recent sport research. Moving beyond traditional mentoring dyads, constellation peer mentoring engages several mentors to provide support to a protégé, ensuring they have access to multiple perspectives and areas of expertise. We implemented a constellation peer-mentoring program with Canadian university student-athletes throughout their competitive seasons. Subsequently, we undertook an instrumental case study to explore participants’ feedback and the perceived benefits of the program. Using reflexive thematic analysis, we interpreted participants’ responses as indicative of traditional mentoring benefits, including reduced transitional stress, feelings of well-being, and feelings of satisfaction. In addition, we determined unique aspects of constellation peer mentoring, such as increased team cohesion, improved help-seeking, an environment that fostered relational mentoring experiences, and the need for leader training. Constellation peer mentoring presents a promising intervention for supporting student-athletes during career transitions.
Ultrahigh dielectric permittivity in oxide ceramics by hydrogenation
Authors: Duong Nguyen Xuan , Jang Ji-Soo , Jung Min-Hyoung , Bae Jong-Seong , Ahn Chang Won , Jin Jong Sung , Ihm Kyuwook , Kim Gyehyeon , Lim So Yeon , Lee Jongmin , Dung Dang Duc , Lee Soonil , Kim Young-Min , Lee Sanghan , Yang Sang Mo , Sohn Changhee , Kim Ill Won , Jeong Hu Young , Baek Seung-Hyub , Kim Tae Heon
Published: February 2023

Boosting dielectric permittivity representing electrical polarizability of dielectric materials has been considered a keystone for achieving scientific breakthroughs as well as technological advances in various multifunctional devices. Here, we demonstrate sizable enhancements of low-frequency dielectric responses in oxygen-deficient oxide ceramics through specific treatments under humid environments. Ultrahigh dielectric permittivity (~5.2 × 10
6
at 1 Hz) is achieved by hydrogenation, when Ni-substituted BaTiO
3
ceramics are exposed to high humidity. Intriguingly, thermal annealing can restore the dielectric on-state (exhibiting huge polarizability in the treated ceramics) to the initial dielectric off-state (displaying low polarizability of ~10
3
in the pristine ceramics after sintering). The conversion between these two dielectric states via the ambient environment–mediated treatments and the successive application of external stimuli allows us to realize reversible control of dielectric relaxation characteristics in oxide ceramics. Conceptually, our findings are of practical interest for applications to highly efficient dielectric-based humidity sensors.
RNA G-quadruplex organizes stress granule assembly through DNAPTP6 in neurons
Authors: Asamitsu Sefan , Yabuki Yasushi , Matsuo Kazuya , Kawasaki Moe , Hirose Yuki , Kashiwazaki Gengo , Chandran Anandhakumar , Bando Toshikazu , Wang Dan Ohtan , Sugiyama Hiroshi , Shioda Norifumi
Published: February 2023

Consecutive guanine RNA sequences can adopt quadruple-stranded structures, termed RNA G-quadruplexes (rG4s). Although rG4-forming sequences are abundant in transcriptomes, the physiological roles of rG4s in the central nervous system remain poorly understood. In the present study, proteomics analysis of the mouse forebrain identified DNAPTP6 as an RNA binding protein with high affinity and selectivity for rG4s. We found that DNAPTP6 coordinates the assembly of stress granules (SGs), cellular phase-separated compartments, in an rG4-dependent manner. In neurons, the knockdown of DNAPTP6 diminishes the SG formation under oxidative stress, leading to synaptic dysfunction and neuronal cell death. rG4s recruit their mRNAs into SGs through DNAPTP6, promoting RNA self-assembly and DNAPTP6 phase separation. Together, we propose that the rG4-dependent phase separation of DNAPTP6 plays a critical role in neuronal function through SG assembly.