bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical outcomes of MAFLD versus NAFLD: A meta‐analysis of observational studies
Authors: Pennisi Grazia , Infantino Giuseppe , Celsa Ciro , Di Maria Gabriele , Enea Marco , Vaccaro Marco , Cannella Roberto , Ciccioli Carlo , La Mantia Claudia , Mantovani Alessandro , Mercurio Francesco , Tilg Herbert , Targher Giovanni , Di Marco Vito , Cammà Calogero , Petta Salvatore
Published: August 2024

Importance

The recent change in terminology from nonalcoholic fatty liver disease (NAFLD) to metabolic dysfunction‐associated fatty liver disease (MAFLD) and metabolic dysfunction‐associated steatotic liver disease (MASLD) highlights the link between hepatic steatosis and metabolic dysfunction, taking out the stigmata of alcohol.

Objective

We compared the effects of NAFLD and MAFLD definitions on the risk of overall and cardiovascular (CV) mortality, liver‐related events (LRE), nonfatal CV events (CVE), chronic kidney disease (CKD), and extra‐hepatic cancers (EHC).

Data Sources and Study Selection

We systematically searched four large electronic databases for cohort studies (published through August 2023) that simultaneously used NAFLD and MAFLD definitions for examining the risk of mortality and adverse CV, renal, or oncological outcomes associated with both definitions. In total, 21 eligible cohort studies were identified. Meta‐analysis was performed using random‐effects modelling.

Results

Compared with those with NAFLD, individuals with MAFLD had significantly higher rates of overall mortality (random‐effect OR 1.12, 95% CI 1.04–1.21, p = .004) and CV mortality (random‐effect OR 1.15, 95% CI 1.04–1.26, p = .004), and a marginal trend towards higher rates of developing CKD (random‐effect OR 1.06, 95% CI 1.00–1.12, p = .058) and EHC events (random‐effect OR 1.11, 95% CI 1.00–1.23, p = .052). We found no significant differences in the risk LREs and nonfatal CVE between MAFLD and NAFLD. Meta‐regression analyses identified male sex and metabolic comorbidities as the strongest risk factors related to the risk of adverse clinical outcomes in MAFLD compared to NAFLD.

Conclusions and Relevance

Individuals with MAFLD have higher rates of overall and CV mortality and higher rates of developing CKD and EHC events than those with NAFLD, possibly due to the dysmetabolic risk profile related to MAFLD.
Insights into the evolutionary and ecological adaption strategies of nirS‐ and nirK‐type denitrifying communities
Authors: Ming Yuzhen , Abdullah Al Mamun , Zhang Dandan , Zhu Wengen , Liu Huanping , Cai Lanlan , Yu Xiaoli , Wu Kun , Niu Mingyang , Zeng Qinglu , He Zhili , Yan Qingyun
Published: August 2024

Denitrification is a crucial process in the global nitrogen cycle, in which two functionally equivalent genes, nirS and nirK, catalyse the critical reaction and are usually used as marker genes. The nirK gene can function independently, whereas nirS requires additional genes to encode nitrite reductase and is more sensitive to environmental factors than nirK. However, the ecological differentiation mechanisms of those denitrifying microbial communities and their adaptation strategies to environmental stresses remain unclear. Here, we conducted metagenomic analysis for sediments and bioreactor samples from Lake Donghu, China. We found that nirS‐type denitrifying communities had a significantly lower horizontal gene transfer frequency than that of nirK‐type denitrifying communities, and nirS gene phylogeny was more congruent with taxonomy than that of nirK gene. Metabolic reconstruction of metagenome‐assembled genomes further revealed that nirS‐type denitrifying communities have robust metabolic systems for energy conservation, enabling them to survive under environmental stresses. Nevertheless, nirK‐type denitrifying communities seemed to adapt to oxygen‐limited environments with the ability to utilize various carbon and nitrogen compounds. Thus, this study provides novel insights into the ecological differentiation mechanism of nirS and nirK‐type denitrifying communities, as well as the regulation of the global nitrogen cycle and greenhouse gas emissions.
Realist analysis of qualitative data in health professions education research
Authors: Rees Charlotte E. , Proctor Dominic W. , Nguyen Van N. B. , Ottrey Ella , Mattick Karen L.
Published: August 2024

Background

Qualitative realist analysis is gaining in popularity in health professions education research (HPER) as part of theory‐driven program evaluation. Although realist approaches such as syntheses and evaluations typically advocate mixed methods, qualitative data dominate currently. Various forms of qualitative analysis have been articulated in HPER, yet realist analysis has not. Although realist analysis is interpretive, it moves beyond description to explain generative causation employing retroductive theorising. Ultimately, it attempts to build and/or ‘test’ (confirm, refute or refine) theory about how, why, for whom, when and to what extent programs work using the context‐mechanism‐outcome configuration (CMOC) heuristic. This paper aims to help readers better critique, conduct and report qualitative realist analysis.

Realist Analysis Methods

We describe four fundamentals of qualitative realist analysis: (1) simultaneous data collection/analysis; (2) retroductive theorising; (3) configurational analysis (involving iterative phases of identifying CMOCs, synthesising CMOCs into demi‐regularities and translating demi‐regularities into program theory); and (4) realist analysis quality (relevance, rigour, richness). Next, we provide a critical analysis of realist analyses employed in 15 HPER outputs—three evaluations and 12 syntheses. Finally, drawing on our understandings of realist literature and our experiences of conducting qualitative realist analysis (both evaluations and syntheses), we articulate three common analysis challenges (coding, consolidation and mapping) and strategies to mitigate these challenges (teamwork, reflexivity and consultation, use of data analysis software and graphical representations of program theory).

Conclusions

Based on our critical analysis of the literature and realist analysis experiences, we encourage researchers, peer reviewers and readers to better understand qualitative realist analysis fundamentals. Realist analysts should draw on relevant realist reporting standards and literature on realist analysis to improve the quality and reporting of realist analysis. Through better understanding the common challenges and mitigation strategies for realist analysis, we can collectively improve the quality of realist analysis in HPER.
Weaning‐associated interventions for ventilated intensive care patients: A scoping review
Authors: Sterr Fritz , Bauernfeind Lydia , Knop Michael , Rester Christian , Metzing Sabine , Palm Rebecca
Published: August 2024

Background

Mechanical ventilation is a core intervention in critical care, but may also lead to negative consequences. Therefore, ventilator weaning is crucial for patient recovery. Numerous weaning interventions have been investigated, but an overview of interventions to evaluate different foci on weaning research is still missing.

Aim

To provide an overview of interventions associated with ventilator weaning.

Study Design

We conducted a scoping review. A systematic search of the Medline, CINAHL and Cochrane Library databases was carried out in May 2023. Interventions from studies or reviews that aimed to extubate or decannulate mechanically ventilated patients in intensive care units were included. Studies concerning children, outpatients or non‐invasive ventilation were excluded. Screening and data extraction were conducted independently by three reviewers. Identified interventions were thematically analysed and clustered.

Results

Of the 7175 records identified, 193 studies were included. A total of six clusters were formed: entitled enteral nutrition (three studies), tracheostomy (17 studies), physical treatment (13 studies), ventilation modes and settings (47 studies), intervention bundles (42 studies), and pharmacological interventions including analgesic agents (8 studies), sedative agents (53 studies) and other agents (15 studies).

Conclusions

Ventilator weaning is widely researched with a special focus on ventilation modes and pharmacological agents. Some aspects remain poorly researched or unaddressed (e.g. nutrition, delirium treatment, sleep promotion).

Relevance to Clinical Practice

This review compiles studies on ventilator weaning interventions in thematic clusters, highlighting the need for multidisciplinary care and consideration of various interventions. Future research should combine different interventions and investigate their interconnection.
Decreases in mucosally‐evoked tachykinin signaling pathways can explain age‐related reductions in murine colonic motility patterns
Authors: Yeoman Mark S. , Fidalgo Sara , Hobby India , Hafeez Ali , Ranson Rachel N. , Saffrey M. Jill , Patel Bhavik Anil
Published: August 2024

Background

Increasing age increases the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to this phenotype is unclear. This study explored the effects of age on key motility patterns in the murine colon and determined the contribution that altered neurokinin 2 (NK2) ‐mediated signaling made to the aging phenotype.

Methods

Mucosal reflexes, colonic migrating motor complexes (CMMCs) and colonic motility assays were explored in isolated ex vivo colons from 3, 12–14, 18‐ and 24‐months old mice and the NK2‐mediated response determined. Electrical field stimulation (EFS) or exogenous drug application were used to explore the role of the mucosa in colonic segments.

Key Results

Aging reduced the force of contraction of the distal colon mucosal reflex, the frequency and force of contraction of CMMCs and the NK2‐mediated component of both motility patterns. Ondansetron, a 5‐HT3 receptor antagonist, blocked a component of both motility patterns in full thickness but not in mucosa‐free segments of the distal colon. 5, hydroxytryptamine (5‐HT) and EFS‐evoked NK2‐dependent contractions were reduced with increasing age. Smooth muscle sensitivity to 5‐HT or neurokinin A (NKA) was not altered with age. In isolated colon motility assays application of NKA decreased transit time in 24‐months colon and the NK2 antagonist GR159897 increased transit times in both 3‐ and 24‐months old colons.

Conclusions and Inferences

Aging impairs key motility patterns in the murine colon. These changes involve a decrease in mucosally‐evoked NK2‐mediated signaling. Targeting NK2‐mediated signaling may provide a novel approach to treating age‐related motility disorders in the lower bowel.
Is auxin the key to improve crop nitrogen use efficiency for greener agriculture?
Authors: Li Shan
Published: August 2024

Strengthening future food security through the application of unsustainable levels of inorganic nitrogen (N) fertilizers to crop fields may exacerbate environmental damage. Coordination of N‐use efficiency (NUE) and plant growth is, therefore, crucial for sustainable agriculture. Auxin plays pivotal roles in developmental and signaling responses that affect NUE. Hence, a better understanding of these processes provides great potential to improve crop NUE. This review summarizes the effects of auxin on N‐related and root developmental processes that either directly or indirectly affect NUE in the model plant Arabidopsis and major crop species to highlight the potential of fostering sustainable agricultural development in the future through modulating auxin‐related processes.
Differential phenotypic plasticity of subalpine trees predicts trait integration under climate warming
Authors: He Rui , Shi Hang , Hu Man , Zhou Quan , Dang Haishan , Zhang Quanfa
Published: August 2024

Understanding limiting factors of phenotypic plasticity is essential given its critical role in shaping biological adaptation and evolution in changing environments. It has been proposed that the pattern of phenotypic correlation could constrain trait plasticity. However, the interplay between phenotypic plasticity and integration has remained contentious.

We experimentally simulated climate warming in juveniles of three subalpine tree species by exposing them to three‐year in situ open‐top chambers (OTCs), and then measured functional plasticity of 72 eco‐physiological traits to evaluate whether phenotypic integration constituted an intrinsic constraint to plasticity. We also tested the relationship between the differences in plasticity and maintenance in trait integration.

Phenotypic plasticity was positively associated with integration in deciduous tree species under warming. The difference in the plasticity of two paired traits could predict their integration in different environments, where traits displaying more similar plasticity were more likely to be correlated.

Our study showed no indication that phenotypic integration constrained plasticity. More importantly, we demonstrated that differential plasticity between traits might result in a notable reorganization of the trait associations, and that warming commonly induced a tighter phenotype. Our study provides new insights into the interplay between phenotypic plasticity and integration in subalpine trees under climate warming.
NPCC4: Climate risk and equity—advancing knowledge toward a sustainable future | Conclusions
Authors: Towers Joel , Leichenko Robin , Braneon Christian , Balk Deborah , Yoon Liv , Wagner Gernot , Ventrella Jennifer , Tchen John Kuo Wei , Rosenzweig Bernice , Orton Philip , Ortiz Luis , Moss Richard , Montalto Franco , McPhearson Timon , McComas Katherine , Marcotullio Peter , Matte Thomas , Maher Nicole , Knowlton Kim , Horton Radley , Foster Sheila , Bader Daniel , Baptista Ana
Published: August 2024

This chapter provides an overview of the major themes, findings, and recommendations from NPCC4. It presents summary statements from each chapter of the assessment which identify salient and pressing issues raised and provides recommendations for future research and for enhancement of climate resiliency. The chapter also outlines a set of broader recommendations for future NPCC work and identifies some key topics for the next assessment.
Effects of fluid shear stress on oral biofilm formation and composition and the transcriptional response of Streptococcus gordonii
Authors: Nairn Brittany L. , Lima Bruno P. , Chen Ruoqiong , Yang Judy Q. , Wei Guanju , Chumber Ashwani K. , Herzberg Mark C.
Published: August 2024

Biofilms are subjected to many environmental pressures that can influence community structure and physiology. In the oral cavity, and many other environments, biofilms are exposed to forces generated by fluid flow; however, our understanding of how oral biofilms respond to these forces remains limited. In this study, we developed a linear rocker model of fluid flow to study the impact of shear forces on Streptococcus gordonii and dental plaque‐derived multispecies biofilms. We observed that as shear forces increased, S. gordonii biofilm biomass decreased. Reduced biomass was largely independent of overall bacterial growth. Transcriptome analysis of S. gordonii biofilms exposed to moderate levels of shear stress uncovered numerous genes with differential expression under shear. We also evaluated an ex vivo plaque biofilm exposed to fluid shear forces. Like S. gordonii, the plaque biofilm displayed decreased biomass as shear forces increased. Examination of plaque community composition revealed decreased diversity and compositional changes in the plaque biofilm exposed to shear. These studies help to elucidate the impact of fluid shear on oral bacteria and may be extended to other bacterial biofilm systems.
Evolution of PIN gene family between monocotyledons and dicotyledons and VvPIN1 negatively regulates freezing tolerance in transgenic Arabidopsis
Authors: Gou Huimin , Lu Shixiong , Guo Lili , Che Lili , Li Min , Zeng Baozhen , Yang Juanbo , Chen Baihong , Mao Juan
Published: August 2024

The PIN‐FORMED (PIN) proteins mediate the auxin flow throughout the plant and have been identified in many species. However, evolution differences in the PIN gene families have not been systematically analyzed, and their functions under abiotic stresses in grape are largely unexplored. In this study, 373 PIN genes were identified from 25 species and divided into 3 subgroups. Physicochemical properties analysis indicated that most of the PIN proteins were unstable alkaline hydrophobic proteins in nature. The synteny analysis showed that the PINs contained strong gene duplication. Motif composition revealed that PIN gene sequence differences between monocotyledons and dicotyledons were due to evolutionary‐induced base loss, and the loss was more common in dicotyledonous. Meanwhile, the codon usage bias showed that the PINs showed stronger codon preference in monocotyledons, monocotyledons biased towards C3s and G3s, and dicotyledons biased towards A3s and T3s. In addition, the VvPIN1 can interact with VvCSN5. Significantly, under freezing treatment, the ion leakage, , H2O2, and malondialdehyde (MDA) were obviously increased, while the proline (Pro) content, peroxidase (POD) activity, and glutathione (GSH) content were decreased in VvPIN1‐overexpressing Arabidopsis compared to the wild type (WT). And quantitative real‐time PCR (qRT‐PCR) showed that AtICE1, AtICE2, AtCBF1, AtCBF2, and AtCBF3 were down‐regulated in overexpression lines. These results demonstrated that VvPIN1 negatively regulated the freezing tolerance in transgenic Arabidopsis. Collectively, this study provides a novel insight into the evolution and a basis for further studies on the biological functions of PIN genes in monocotyledons and dicotyledons.
Morphological and immunohistochemical characteristics of diffuse seminoma in horses: A case report
Authors: Batista Lucas Andrê Silva , de Alencar Santos Júnior Dinamérico , Rodrigues Alexandra Soares , Menezes Artur Azevedo , do Nascimento Maria Jussara Rodrigues , de Galiza Glauco Jose Nogueira , de Medeiros Dantas Antônio Flávio , Frade Maria Talita Soares
Published: August 2024

The present study describes the morphological and immunohistochemical characteristics of a case of diffuse seminoma in a 16‐year‐old male mixed‐breed horse. According to the owner, the animal's left testicle had been gradually increasing in size over a period of 2 months. On palpation, the testicle had a firm consistency, with no sensitivity to digital pressure, was adhered to the scrotum and measuring 16 cm × 8 cm. In the ultrasound examination, it presented a heterogeneous texture and areas of hypoechogenic echogenicity without visualization of the mediastinum. Therefore, the bilateral orchiectomy was performed. After the surgical procedure, it was found that the affected testicle presented a firm mass measuring 9 cm × 7 cm × 3.5 cm. Histologically, a multilobulated, non‐encapsulated and invasive tumour mass was found, which replaced the seminiferous tubules, consisting of polygonal cells arranged in a mantle that varied from cohesive to loosely cohesive, supported by a scarce fibrous stroma. In the immunohistochemical examination, the neoplastic cells showed positive immunolabelling for OCT4 and C‐KIT. In this report, the physical examination combined with the ultrasonographic examination were fundamental to the therapeutic management of the case, and the final diagnosis was made after histopathological and immunohistochemical tests.
Ventilation heterogeneity is increased in adults exposed to coal mine fire‐related PM2.5
Authors: McCrabb Thomas , Borg Brigitte , Gao Caroline X. , Smith Catherine , O'Sullivan Claire F. , Brown David , Ikin Jillian , Makar Annie , Lane Tyler , Abramson Michael J. , Thompson Bruce R.
Published: August 2024

Background and Objectives

The Hazelwood Health Study was set up to study long‐term health effects of a mine fire that blanketed residents of the Latrobe Valley with smoke for 45 days in 2014. The Respiratory Stream specifically assessed the impact of fine particulate matter <2.5 μm diameter (PM2.5) exposure from mine fire smoke on lung health. The multiple breath nitrogen washout (MBW) test assesses ventilation heterogeneity, which may detect sub‐clinical airways dysfunction not identified using standard tests such as spirometry. This analysis assessed the association of PM2.5 exposure with measures of ventilation heterogeneity.

Methods

Exposed (Morwell) and unexposed (Sale) participants were recruited 3.5–4 years after the fire from those who had participated in an Adult Survey. MBW was performed to measure lung clearance index (LCI), functional residual capacity (FRC), acinar (Sacin) and conductive (Scond) ventilation heterogeneity. PM2.5 exposure was estimated with emission and chemical transport models. Multivariable linear regression models were fitted controlling for confounders.

Results

We recruited 519 participants. MBW tests were conducted on 504 participants with 479 acceptable test results (40% male; 313 exposed, 166 unexposed). Exposure to mine fire‐related PM2.5 was associated with increasing Scond (β = 1.57/kL, 95%CI: 0.20–2.95, p = 0.025), which was comparable to the estimated effect on Scond of 4.7 years of aging. No other MBW outcomes were statistically different.

Conclusion

Increasing exposure to PM2.5 was associated with increased ventilation heterogeneity in the conductive region of the lungs 4 years after the event.

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A Case Report of a Hemodialysis Patient With Coagulation Factor XI and Factor XII Deficiencies
Authors: Li Xueying , Wang Yong
Published: August 2024

Coagulation Factor XI (FXI) and Factor XII (FXII) deficiencies are rare. FXI deficiency is associated with a bleeding disorder, while FXII deficiency is not, but both can cause chronic prolongation of activated partial thromboplastin time and impair thrombus formation, posing great challenges for hemodialysis anticoagulation. Traditionally, heparin or low‐molecular‐weight heparins (LMWHs) are not considered a safe anticoagulation option for patients with increased bleeding risk. In this context, FXI and FXII have received substantial attention as targets for new anticoagulants. We present the case of a 68‐year‐old woman with combined FXI and FXII deficiencies who successfully underwent hemodialysis with anticoagulation using a low dose of LMWHs. This case highlights that FXI and FXII deficiencies are associated with anticoagulant effects, which can reduce the dosage of anticoagulant during hemodialysis. With careful monitoring, an appropriate dosage of LMWHs is still an acceptable option for patients with a bleeding risk.
BvCGT1‐mediated differential distribution of flavonoid C‐glycosides contributes to plant's response to UV‐B stress
Authors: Zeng Huihui , Li Shuai , Wang Kaixuan , Dai Yiqun , Sun Lanlan , Gao Yue , Yi Shanyong , Li Junde , Xu Sheng , Xie Guoyong , Zhu Yan , Zhao Yucheng , Qin Minjian
Published: August 2024

C‐glycosides are a predominant class of flavonoids that demonstrate diverse medical properties and plant physiological functions. The chemical stability, structural diversity, and differential aboveground distribution of these compounds in plants make them ideal protectants. However, little is known about the transcriptional regulatory mechanisms that play these diverse roles in plant physiology. In this study, chard was selected from 69 families for its significantly different flavonoid C‐glycosides distributions between the aboveground and underground parts to investigate the role and regulatory mechanism of flavonoid C‐glycosides in plants. Our results indicate that flavonoid C‐glycosides are affected by various stressors, especially UV‐B. Through cloning and validation of key biosynthetic genes of flavonoid C‐glycosides in chard (BvCGT1), we observed significant effects induced by UV‐B radiation. This finding was further confirmed by resistance testing in BvCGT1 silenced chard lines and in Arabidopsis plants with BvCGT1 overexpression. Yeast one‐hybrid and dual‐luciferase assays were employed to determine the underlying regulatory mechanisms of BvCGT1 in withstanding UV‐B stress. These results indicate a potential regulatory role of BvDof8 and BvDof13 in modulating flavonoid C‐glycosides content, through their influence on BvCGT1. In conclusion, we have effectively demonstrated the regulation of BvCGT1 by BvDof8 and BvDof13, highlighting their crucial role in plant adaptation to UV‐B radiation. Additionally, we have outlined a comprehensive transcriptional regulatory network involving BvDof8 and BvDof13 in response to UV‐B radiation.
Skin fibrosis is accompanied by increased expression of secreted frizzled‐related protein‐2
Authors: Dolivo David M. , Rodrigues Adrian E. , Sun Lauren S. , Mustoe Thomas A. , Hong Seok Jong , Galiano Robert D.
Published: August 2024

Dermal fibrosis is a consequence of damage to skin and is accompanied by dysfunction and cosmetic disfigurement. Improved understanding of the pathological factors driving skin fibrosis is critical to development of therapeutic modalities. Here, we describe that the Wnt signalling antagonist SFRP2 is upregulated in organotypic keratinocyte cultures upon experimental reduced hydration, a model that simulates the aberrant epidermal barrier state characteristic of several skin pathologies, including those that manifest in development of fibrosis. Consistent with this, we find that SFRP2 is overexpressed in both the dermis and epidermis of human hypertrophic scar tissue and lesional tissue of a mouse scleroderma model. Knockdown of SFRP2 expression in human fibroblasts antagonises proliferation and myofibroblast differentiation, including deposition of type I collagen, suggesting that SFRP2 signalling in fibroblasts may contribute to propagation of fibrosis in hypertrophic scar, as well as in other clinical indications characterised by skin fibrosis.
Effects of a Three-Dimensional-Printed Atomizer Component on Fuel-Spray and Flame Characteristics of a Jet-Stabilized Compact Gas Turbine Combustor Fed With Liquid Fuels
Authors: Kim Haisol , Pareja Jhon , Lammel Oliver
Published: August 2024

In this work, the effects of replacing an atomizer component of a confined jet-stabilized gas turbine combustor with a three-dimensional (3D)-printed part have been studied. The part is called airblast, and it serves as a wall that collects and flows liquid droplets for a secondary atomization. Therefore, the liquid–surface interaction on the rough surface of the 3D-printed part was of interest. The combustor was operated under various conditions with either a conventionally machined airblast or the 3D-printed airblast. Flames with two liquid fuels were studied for fuel flexibility, and the position of a primary fuel injection was varied to study the influence of the liquid-surface interaction length. Load flexibility was investigated with air jet velocity settings, and flame equivalence ratios of ϕ = 0.8 and 1.0 were tested. Shadowgraphy-based particle tracking analyses presented a reduced atomization performance with the 3D-printed airblast, showing large droplet size distributions. However, no significant change in the combustor performance was observed from OH* chemiluminescence images and emission data, which confirms the versatility of the combustor and assures the compatibility of 3D-printed components with the combustor of this study.
Nonpremixed Approaches for Fuel Flexible, Low NOx Combustors in High-Efficiency Gas Turbines
Authors: Emerson Benjamin , Patel Shivam J. , Gubbi Srujan , McKinney Randal G. , Wu David , Noble David R. , Lieuwen Tim
Published: August 2024

Lean, premixed combustor designs have almost completely replaced nonpremixed combustors for industrial gas turbine applications where NOx emissions are regulated. Nonetheless, these designs have also introduced turndown and fuel flexibility constraints and made combustion instabilities and flashback more problematic. Future gas turbine applications will require combustors to accommodate a range of alternative fuels, provide operational flexibility, and compete for services with a host of new technologies, including energy storage and fuel cells. The purpose of this paper is to propose nonpremixed, multistage designs for the next generation of high turndown, high fuel flexibility, low NOx combustion designs—referred to here as a Nonpremixed, Rich, Relaxation, Lean (NRRL) combustor. The key concept, we explore is nonpremixed combustion, followed by additional fuel mixing to locally fuel-rich conditions, a relaxation stage, and then a lean stage. This nonpremixed approach can handle essentially any fuel composition, including pure hydrogen, liquid fuels, pure methane, pure ammonia, and any combination in between while breaking the NOx-CO tradeoff and reducing combustion instability risk. This paper provides chemical reactor network modeling calculations to identify key kinetic processes and time scales required for such a concept. This concept has completely inverted sensitivities from lean, premixed systems which prefer short residence times, low pressures, and low temperatures to minimize NO formation. This concept prefers long residence times, high pressures, and high temperatures, indicating a very different set of design trades for part load and off-design performance.
Analysis of Thermo-Acoustic Instabilities Induced by Hydrogen Swirling Flames
Authors: Vaysse Nicolas , Durox Daniel , Vicquelin Ronan , Candel Sébastien , Renaud Antoine
Published: August 2024

A considerable research effort has been concerned combustion dynamics of systems fed with hydrocarbon fuels. The case of pure hydrogen/air flames deserves to be specifically considered because hydrogen is highly reactive, has a tendency to develop thermo-diffusive instabilities, is envisaged in many future applications, most notably in gas turbines, and is less well documented. Thermo-acoustic instabilities of pure hydrogen flames are here investigated in a configuration where hydrogen is injected in-crossflow in a swirling stream of air. The study is focused on operating conditions that lead to oscillatory regimes. Using Abel-transformed phase-averaged images of OH* emission and visible light emission in burnt gases, it is shown that the OH* signal evolves approximately in phase with the heat release rate. This signal is then used to determine the local Rayleigh source term that feeds acoustic energy in the oscillation. The contributions of this term are examined using a space–time analysis based on an integration of the source term in the transverse direction. This procedure allows a detailed analysis of the processes that contribute to the acoustic energy in the system, showing, in particular, that a strong positive addition of acoustic energy results from a roll-up of the flame tip and from the quick cyclic back propagation of the flame to the injector tip. A global integration of the Rayleigh source term is then used together with a volume-integrated acoustic energy to estimate the growth rate associated with these driving processes and estimate the damping rate. A special experimental method is then exploited to determine the effective growth rate of the instability. The system allowing a sweep in frequency, self-sustained instabilities obtained at different frequencies are used to extract the specific instability frequency band of the burner. Finally, the flame is externally forced in order to measure its flame-describing function.
Mass and Heat Exchange in Rotating Compressor Cavities With Variable Cob Separation
Authors: Nicholas Tom E. W. , Pernak Mikolaj J. , Lock Gary D. , Scobie James A. , Tang Hui
Published: August 2024

Next generation aeroengines will operate at ever-increasing pressure ratios with smaller cores, where the control of blade-tip clearances across the flight cycle is an emerging design challenge. Such clearances are affected by the thermal expansion of the compressor disks that hold the blades, where acute thermal stresses govern operating life. The cavities formed by corotating disks feature a heated shroud at high radius and cooler cobs at low radius. A three-dimensional, unsteady and unstable flow structure is induced by destabilizing buoyancy forces. The radial distribution of disk temperature is driven by a conjugate heat transfer at Grashof numbers of order 1013. Such flows are further influenced by the heat and mass exchange with an axial throughflow of cooling air at low radius, where the interaction depends on the Rossby number and separation of the disk cobs. This paper is the first to study the effect of cob separation ratio on mass and heat exchange for compressor cavities. A model is developed to predict the cavity-throughflow interaction, and disk and fluid-core temperatures. The judicious use of a physics-based methodology provides reliable, reduced-order solutions to the complex conjugate problem, thereby making it appropriate for practical engine thermo-mechanical design. The model is validated by detailed experimental measurements using the Bath Compressor Cavity Rig, where variable disk cob spacings were investigated over a range of engine-representative conditions. The unsteady pressure measurements collected in the frame of reference of the rotating disks reveal new insight into the fundamentally aperiodic nature of the flow structure. This new understanding of heat transfer informs an expedient reduced-order model and enables more efficient design of future high pressure-ratio aeroengines.
A Surrogate Model Approach to Predict Operations and Maintenance Cost for Combined Cycle Power Plant
Authors: Choi Woosung , Webb Bobby M. , Noble David R.
Published: August 2024

In the transition toward carbon neutrality by 2050, renewable energy sources are gaining prominence. The variability of renewable energy poses challenges for power grid stability. Gas turbine combined cycle (GTCC) power plants play a crucial role in grid stabilization, especially during peak loads. In GTCC power generation, operations and maintenance (O&M) cost is the next most important after fuel and initial investment cost, and it is necessary to predict O&M cost according to changes in the operating environment for efficient and stable operation of GTCC power plant. However, various uncertainties exist when estimating O&M costs because actual design information is limitedly disclosed due to maintenance contracts between operators and manufacturers, and it is difficult to obtain accurate variables according to the operation condition. In this paper, the correlation was analyzed considering the uncertainty of the factors affecting the O&M cost of the GTCC power plant through sensitivity analysis, and the main factors were defined. In addition, a surrogate model was proposed that can quickly calculate fixed and variable O&M cost according to changing operating scenarios such as shortening startup time, enhancing ramp rate, or lower minimum load. Through the case study, short-term and long-term O&M costs can be estimated in the operating environment of the GTCC power plant currently being operated. Additionally, the model facilitates cost projections for new hybrid GTCC facilities (combining gas turbines with energy storage systems), aiding long-term investment planning.
Reverse Thrust Aerodynamics of Variable Pitch Fans With Inlet Distortion
Authors: Ma Kwun Yeung , Hall Cesare A. , Wang Tianhou , Williams Tim S.
Published: August 2024

Variable pitch fans (VPFs) can improve the operability of low pressure ratio fan systems by repitching the rotor blades. If a variable pitch fan can generate sufficient reverse thrust on landing, it will also eliminate the need for heavy, cascade-type thrust reversers. However, any reverse thrust generation is impacted by high levels of inlet distortion generated as air is drawn into the exhaust nozzle. This paper uses both Reynolds-averaged Navier–Stokes (RANS) computations and low-speed rig experiments to explore how a representative inlet distortion from the engine installation affects the aerodynamics and performance of a variable pitch fan operating in reverse thrust mode. The simulations and the experiments both show that the distortion from the engine installation leads to a highly three-dimensional flow field with a large recirculation region within the bypass duct. This is in contrast to the primarily axial flow that is produced for a case with uniform freestream inlet conditions. The distortion substantially redistributes the mass flow, thrust, and power in the engine. Streamline tracking combined with a power balance analysis reveals that there is highly radial flow within the fan rotor and almost all of the power from the fan is used to drive the recirculating flow in the bypass duct, which generates high loss and has a high total temperature. The recirculation reduces the net mass flow through the engine to around 5% of a uniform inflow case and the effective reverse thrust is greatly reduced. With uniform inflow, the net reverse thrust was found to be 35% of the nominal takeoff thrust. With inlet distortion present, this was reduced to 20%. This demonstrates the importance of designing and operating variable pitch fan systems to minimize the reverse thrust inlet distortion.
Design-Point Techno-Economics of Brayton Cycle PTES for Combined Heat and Power
Authors: Neises Ty , McTigue Joshua
Published: August 2024

Pumped thermal energy storage (PTES) systems are grid batteries that use heat pumps to create both hot and cold thermal energy stores when there is excess electricity and then use a power cycle to convert the thermal energy into electricity when there is demand for electricity. In normal operation, Joule–Brayton PTES discharges low-grade heat at temperatures useful for thermal energy consumers like district and industrial heating. Furthermore, PTES designs, like conventional combined heat and power (CHP) technology, can be modified to sacrifice some round-trip efficiency (RTE) to increase the temperature of heat rejection. This paper uses design-point performance and cost models that provide a detailed understanding of the efficiency and cost tradeoffs of rejecting heat at various temperatures in ideal-gas Brayton PTES configurations. First, we keep the heat rejection in its nominal location in the PTES system: in the discharge cycle after the low-pressure exit of the recuperator before the cold-storage heat exchanger. Next, we move the heat rejection to the discharge turbine exit. We define design-point metrics that isolate both the cost and performance penalty associated with the hotter heat rejection and attribute it exclusively to the heat economic metrics. Finally, we estimate the performance of electric heater technology to generate heat at equivalent temperatures. We find that the levelized cost of heat (LCOH), including the cost of thermal energy storage (TES) buffering the PTES and heat off-taker, compares favorably versus electric technologies and is less than the cost of natural gas for low temperature scenarios and competitive with the cost of natural gas in some regions of the contiguous U.S. in high temperature scenarios.
Computer-assisted syllable analysis of continuous speech as a measure of child speech disorder
Authors: Speights Marisha L , MacAuslan Joel , Boyce Suzanne
Published: August 2024

In this study, a computer-driven, phoneme-agnostic method was explored for assessing speech disorders (SDs) in children, bypassing traditional labor-intensive phonetic transcription. Using the SpeechMark® automatic syllabic cluster (SC) analysis, which detects sequences of acoustic features that characterize well-formed syllables, 1952 American English utterances of 60 preschoolers were analyzed [16 with speech disorder present (SD-P) and 44 with speech disorder not present (SD-NP)] from two dialectal areas. A four-factor regression analysis evaluated the robustness of seven automated measures produced by SpeechMark® and their interactions. SCs significantly predicted SD status (p < 0.001). A secondary analysis using a generalized linear model with a negative binomial distribution evaluated the number of SCs produced by the groups. Results highlighted that children with SD-P produced fewer well-formed clusters [incidence rate ratio (IRR) = 0.8116, p ≤ 0.0137]. The interaction between speech group and age indicated that the effect of age on syllable count was more pronounced in children with SD-P (IRR = 1.0451, p = 0.0251), suggesting that even small changes in age can have a significant effect on SCs. In conclusion, speech status significantly influences the degree to which preschool children produce acoustically well-formed SCs, suggesting the potential for SCs to be speech biomarkers for SD in preschoolers.
On the vortex dynamical contribution to the emission of infrasound from tornadoes
Authors: Liang Bin , Waxler Roger , Markowski Paul
Published: August 2024

Previous field experiments support the claim that a tornado can radiate discernible infrasound between 0.5 and 10 Hz. The physical mechanisms of tornado sound generation are still not fully understood, although several potential mechanisms have been proposed. In this paper, the theory of vortex sound is applied to the sound radiation from two numerical tornado simulations based on large eddy simulations. There are two different vortex-related mechanisms in distinct frequency regimes. It is found that rotation of a non-axisymmetric vorticity field produces low-frequency infrasound less than 2.0 Hz. High-frequency tornado infrasound can be attributed to more complex vortex dynamics such as vortex merging.
An Ecological Investigation of Polish Olympic Coaches’ Career Pathways and Their Experiences of Career Transition to Olympic Coaching Roles
Authors: Darpatova-Hruzewicz Donka , Marek Piotr , Kaminski Kamil
Published: August 2024

Most research on coaching adopts a Western, predominantly Anglo-Saxon, vantage point. This study sought to fill the gap in the literature by providing an Eastern European perspective on transition to high-performance coaching. Ten Polish Olympic coaches were interviewed to glean insights into their career pathways, cumulatively spanning the last three decades. First, using abductive analysis, three patterns of nonlinear career pathways were identified: teacher-track, club-coach track and athlete fast-track. Next, contextual and reflective thematic analyses were employed to examine the environmental constraints affecting role transitions. Consequently, drawing on Bronfenbrenner’s bioecological model, the Ecological Model for Coach Development was proposed to offer an alternative perspective on career transitions. The findings provide evidence for the situated and relational nature of career transitions as processes occurring in nested environmental contexts. We claim that advancing knowledge on transitions requires not only zooming into coaches’ lived experiences of transitioning in/out of coaching roles, but also zooming out on macrolevel societal transformation processes, historically rooted values and belief systems, as well as mesolevel institutional constraints that steer career pathways and shape experiences. The study’s ecological orientation has the potential to enhance coaching education and practice by accounting for contextual complexity and temporality.
Does Attraction Toward Physical Activity Predict Physical Activity Behavior in Older Adults?
Authors: Hudgins Brynn L. , Seo Yeongjun , Bittel Kelsey M. , Williams Kemiah , Hevel Derek J. , Labban Jeffrey D. , Maher Jackie P.
Published: August 2024

Background/Objectives: Few studies have investigated associations between the motivational outcome based on physical activity (PA) affective experiences (i.e., attraction vs. antipathy toward PA) and behavior. This study investigated cross-sectional and longitudinal associations between attraction (vs. antipathy) toward PA and device-based PA in older adults. Methods: Older adults (n = 139; 71% female, Mage = 70.5) completed assessments of attraction (vs. antipathy) toward PA and 14 days of device-based accelerometry at Times 1 and 2. Results: Greater attraction toward PA at Time 1 was associated with greater steps (β = 5.31, p < .01) and moderate to vigorous intensity PA (β = 3.08, p < .05) at Time 1. Greater attraction toward PA at Time 1 was not significantly associated with steps or moderate to vigorous intensity PA at Time 2. Conclusion: Greater emphasis on resultant motivation from PA affective experiences may be useful in promoting PA in older adults. Significance/Implications: In spite of mixed findings in the present study, there is strong evidence that positive affective responses during a single bout of PA play an important role in predicting future engagement. Yet, affective experiences during PA can be individualistic and often influenced by contextual factors. Interventions designed to increase PA should focus on factors that may create positive affective experiences for participants.
Extensive Familiarization Is Required Before Assessing Acute Changes in Multiple Object Tracking Performance
Authors: Moon Jessica M. , Pinette John , Khwaja Aneesa , Fontenot Aubrey , Gibbs Violette , Dufner Trevor J. , Wells Adam J.
Published: August 2024

Context: The Neurotracker CORE assessment is an 8-minute multiple object tracking (MOT) program used in sport science research and clinical rehabilitation as a perceptual-cognitive training tool; however, it has garnered interest for its potential use as an acute assessment of cognitive performance. Although some data exist regarding the learning effect of repeated exposures, it is often overlooked with investigators focusing primarily on the presence of transfer effects to other cognitive realms. As a result, exclusive data on the effect of repeated testing, or subsequent periods of no testing (ie, detraining) on test–retest reliability, and on MOT performance are sparse. Design: Repeated-measures/reliability. Methods: Twenty-three recreationally active men and women completed 15 training sessions consisting of 2 CORE assessments per session (30 assessments). Participants were randomized to either 1 or 2 weeks of detraining prior to completing 15 retraining sessions (30 assessments). Training and retraining periods were divided into 10 blocks (3 assessments/block) for analysis. MOT speed threshold (MOT-ST), consistency, fastest trial score success speed, lowest trial score miss speed, the number of perfect, near misses, and significant miss trials within each block were used to determine performance. Intraclass correlation coefficient, standard error of measurement, and minimal detectable change were used to determine reliability. Results: Significant improvements in MOT-ST and fastest trial score success speed were noted within training blocks 1 to 6 and 1 to 7, respectively (P < .05). MOT-ST and fastest trial score success speed demonstrated excellent test–retest reliability between blocks 8 and 9. There was no effect of detraining period on performance during retraining. Conclusions: Eighteen tests are necessary to overcome training effects and establish a reliable baseline when MOT-ST is used as the performance outcome. Detraining periods up to 2 weeks did not impact performance. The average of 3 discrete tests should be used when assessing MOT-ST performance.