Size Heterogeneity Research Articles

Effects of ranolazine on the arrhythmic substrate in hypertrophic cardiomyopathy.

Introduction: Hypertrophic cardiomyopathy (HCM) is a leading cause of lethal arrhythmias in the young. Although the arrhythmic substrate has been hypothesised to be amenable to late Na+ block with ranolazine, the specific mechanisms are not fully understood. Therefore, this study aimed to investigate the substrate mechanisms of safety and antiarrhythmic efficacy of ranolazine in HCM. Methods: Computational models of human tissue and ventricles were used to simulate the electrophysiological behaviour of diseased HCM myocardium for variable degrees of repolarisation impairment, validated against in vitro and clinical recordings. S1-S2 pacing protocols were used to quantify arrhythmic risk in scenarios of (i) untreated HCM-remodelled myocardium and (ii) myocardium treated with 3µM, 6µM and 10µM ranolazine, for variable repolarisation heterogeneity sizes and pacing rates. ECGs were derived from biventricular simulations to identify ECG biomarkers linked to antiarrhythmic effects. Results: 10µM ranolazine given to models manifesting ventricular tachycardia (VT) at baseline led to a 40% reduction in number of VT episodes on pooled analysis of >40,000 re-entry inducibility simulations. Antiarrhythmic efficacy and safety were dependent on the degree of repolarisation impairment, with optimal benefit in models with maximum JTc interval <370ms. Ranolazine increased risk of VT only in models with severe-extreme repolarisation impairment. Conclusion: Ranolazine efficacy and safety may be critically dependent upon the degree of repolarisation impairment in HCM. For moderate repolarisation impairment, reductions in refractoriness heterogeneity by ranolazine may prevent conduction blocks and re-entry. With severe-extreme disease substrates, reductions of the refractory period can increase re-entry sustainability.

Extracellular Vesicles from Scedosporium apiospermum Mycelial Cells: Implication for Fungal-Host Interplays.

The release of extracellular vesicles (EVs) has been implicated as an alternative transport mechanism for the passage of macromolecules through the fungal cell wall, a phenomenon widely reported in yeasts but poorly explored in mycelial cells. In the present work, we have purified and characterized the EVs released by mycelia of the emerging, opportunistic, widespread and multidrug-resistant filamentous fungus Scedosporium apiospermum. Transmission electron microscopy images and light scattering measurements revealed the fungal EVs, which were observed individually or grouped with heterogeneous morphology, size and electron density. The mean diameter of the EVs, evaluated by the light scattering technique, was 179.7 nm. Overall, the structural stability of S. apiospermum EVs was preserved during incubation under various storage conditions. The lipid, carbohydrate and protein contents were quantified, and the EVs' protein profile was evidenced by SDS-PAGE, revealing proteins with molecular masses ranging from 20 to 118 kDa. Through immunoblotting, ELISA and immunocytochemistry assays, antigenic molecules were evidenced in EVs using a polyclonal serum (called anti-secreted molecules) from a rabbit inoculated with conditioned cell-free supernatant obtained from S. apiospermum mycelial cells. By Western blotting, several antigenic proteins were identified. The ELISA assay confirmed that the anti-secreted molecules exhibited a positive reaction up to a serum dilution of 1:3200. Despite transporting immunogenic molecules, S. apiospermum EVs slightly induced an in vitro cytotoxicity effect after 48 h of contact with either macrophages or lung epithelial cells. Interestingly, the pretreatment of both mammalian cells with purified EVs significantly increased the association index with S. apiospermum conidia. Furthermore, EVs were highly toxic to Galleria mellonella, leading to larval death in a typically dose- and time-dependent manner. Collectively, the results represent the first report of detecting EVs in the S. apiospermum filamentous form, highlighting a possible implication in fungal pathogenesis.

Prehabilitation in Adults Undergoing Cancer Surgery: A Comprehensive Review on Rationale, Methodology, and Measures of Effectiveness.

Cancer surgery places a significant burden on a patients' functional status and quality of life. In addition, cancer surgery is fraught with postoperative complications, themselves influenced by a patient's functional status. Prehabilitation is a unimodal or multimodal strategy that aims to increase a patient's functional capacity to reduce postoperative complications and improve postoperative recovery and quality of life. In most cases, it involves exercise, nutrition, and anxiety-reducing interventions. The impact of prehabilitation has been explored in several types of cancer surgery, most commonly colorectal and thoracic. Overall, the existing evidence suggests prehabilitation improves physiological outcomes (e.g., lean body mass, maximal oxygen consumption) as well as clinical outcomes (e.g., postoperative complications, quality of life). Notably, the benefit of prehabilitation is additional to that of enhanced recovery after surgery (ERAS) programs. While safe, prehabilitation programs require multidisciplinary coordination preoperatively. Despite the existence of numerous systematic reviews and meta-analyses, the certainty of evidence demonstrating the efficacy and safety of prehabilitation is low to moderate, principally due to significant methodological heterogeneity and small sample sizes. There is a need for more large-scale multicenter randomized controlled trials to draw strong clinical recommendations.

Coordinated distributed experiments in ecology do not consistently reduce heterogeneity in effect size

Ecological meta‐analyses usually exhibit high relative heterogeneity of effect size: most among‐study variation in effect size represents true variation in mean effect size, rather than sampling error. This heterogeneity arises from both methodological and ecological sources. Methodological heterogeneity is a nuisance that complicates the interpretation of data syntheses. One way to reduce methodological heterogeneity is via coordinated distributed experiments, in which investigators conduct the same experiment at different sites, using the same methods. We tested whether coordinated distributed experiments in ecology exhibit 1) low heterogeneity in effect size, and 2) lower heterogeneity than meta‐analyses, using data on 17 effects from eight coordinated distributed experiments, and 406 meta‐analyses. Consistent with our expectations, among‐site heterogeneity typically comprised &lt;50% of the variance in effect size in distributed experiments. In contrast, heterogeneity within and among studies typically comprised &gt;90% of the variance in effect size in meta‐analyses. However, this difference largely reflected the small size of most coordinated distributed experiments, and was no longer significant after controlling for size (number of studies or sites). These results are consistent with the hypothesis that methodological heterogeneity rarely comprises a substantial fraction of variance in effect size in ecology. We also conducted pairwise comparisons of absolute heterogeneity between coordinated distributed experiments and meta‐analyses on the same topics. Coordinated distributed experiments did not consistently exhibit lower absolute heterogeneity in effect size than meta‐analyses on the same topics. Our findings suggest that coordinated distributed experiments rarely increase uniformity of results by reducing methodological heterogeneity. Our results help refine the numerous distinct reasons for conducting coordinated distributed experiments.

Exploring alveolar recruitability using positive end-expiratory pressure in mice overexpressing TGF-β1: a structure–function analysis

Pre-injured lungs are prone to injury progression in response to mechanical ventilation. Heterogeneous ventilation due to (micro)atelectases imparts injurious strains on open alveoli (known as volutrauma). Hence, recruitment of (micro)atelectases by positive end-expiratory pressure (PEEP) is necessary to interrupt this vicious circle of injury but needs to be balanced against acinar overdistension. In this study, the lung-protective potential of alveolar recruitment was investigated and balanced against overdistension in pre-injured lungs. Mice, treated with empty vector (AdCl) or adenoviral active TGF-β1 (AdTGF-β1) were subjected to lung mechanical measurements during descending PEEP ventilation from 12 to 0 cmH2O. At each PEEP level, recruitability tests consisting of two recruitment maneuvers followed by repetitive forced oscillation perturbations to determine tissue elastance (H) and damping (G) were performed. Finally, lungs were fixed by vascular perfusion at end-expiratory airway opening pressures (Pao) of 20, 10, 5 and 2 cmH2O after a recruitment maneuver, and processed for design-based stereology to quantify derecruitment and distension. H and G were significantly elevated in AdTGF-β1 compared to AdCl across PEEP levels. H was minimized at PEEP = 5–8 cmH2O and increased at lower and higher PEEP in both groups. These findings correlated with increasing septal wall folding (= derecruitment) and reduced density of alveolar number and surface area (= distension), respectively. In AdTGF-β1 exposed mice, 27% of alveoli remained derecruited at Pao = 20 cmH2O. A further decrease in Pao down to 2 cmH2O showed derecruitment of an additional 1.1 million alveoli (48%), which was linked with an increase in alveolar size heterogeneity at Pao = 2–5 cmH2O. In AdCl, decreased Pao resulted in septal folding with virtually no alveolar collapse. In essence, in healthy mice alveoli do not derecruit at low PEEP ventilation. The potential of alveolar recruitability in AdTGF-β1 exposed mice is high. H is optimized at PEEP 5–8 cmH2O. Lower PEEP folds and larger PEEP stretches septa which results in higher H and is more pronounced in AdTGF-β1 than in AdCl. The increased alveolar size heterogeneity at Pao = 5 cmH2O argues for the use of PEEP = 8 cmH2O for lung protective mechanical ventilation in this animal model.

Paradox of life after work: A systematic review and meta-analysis on retirement anxiety and life satisfaction.

Retirement is a pivotal life transition that often changes routines, identity, and objectives. With increasing life expectancies and evolving societal norms, examining the interplay between retirement anxiety and life satisfaction is vital. This study delves into this relationship, recognising the complexities of retirement. A systematic review and meta-analysis followed PRISMA guidelines. Research from 2003 to 2023 was sourced from databases like CINAHL, PubMed/Medline, PsycINFO, ERIC, and Google Scholar, focusing on diverse methodologies and outcomes related to retirement registered in Prospero database (CRD42023427949). The quality assessment used an eight-criterion risk of bias scale, and analyses included qualitative and quantitative approaches, such as random-effects meta-analysis and moderator analyses. After reviewing 19 studies with varied geographical and demographic scopes, a mixed relationship between retirement and life satisfaction emerged: 32% of studies reported a positive relationship, 47% were negative, and 21% found no significant correlation. Meta-analysis indicated high heterogeneity and non-significant mean effect size, suggesting no consistent impact of retirement on life satisfaction. Moderator analyses highlighted the influence of measurement tools on outcomes. The findings reveal a complex interplay between retirement anxiety and life satisfaction, stressing the need for holistic retirement policies that encompass mental health, social integration, and adaptability, focusing on cultural sensitivity. Challenges include potential biases in data sources, methodological diversity, the scarcity of longitudinal studies, and difficulties in addressing recent societal shifts, like the COVID-19 pandemic. Variability in measurement tools and possible publication bias may have also influenced results. This study contributes to understanding retirement, emphasising the relationship between retirement anxiety and life satisfaction. It advocates for ongoing, detailed, culturally informed research to grasp retirement's multifaceted aspects fully.

Comparative analysis and classification of highly divergent mouse rDNA units based on their intergenic spacer (IGS) variability.

Ribosomal DNA (rDNA) repeat units are organized into tandem clusters in eukaryotic cells. In mice, these clusters are located on at least eight chromosomes and show extensive variation in the number of repeats between mouse genomes. To analyze intra- and inter-genomic variation of mouse rDNA repeats, we selectively isolated 25 individual rDNA units using Transformation-Associated Recombination (TAR) cloning. Long-read sequencing and subsequent comparative sequence analysis revealed that each full-length unit comprises an intergenic spacer (IGS) and a ∼13.4 kb long transcribed region encoding the three rRNAs, but with substantial variability in rDNA unit size, ranging from ∼35to ∼46 kb. Within the transcribed regions of rDNA units, we found 209 variants, 70 of which are in external transcribed spacers (ETSs); but the rDNA size differences are driven primarily by IGS size heterogeneity, due to indels containing repetitive elements and some functional signals such as enhancers. Further evolutionary analysis categorized rDNA units into distinct clusters with characteristic IGS lengths; numbers of enhancers; and presence/absence of two common SNPs in promoter regions, one of which is located within promoter (p)RNA and may influence pRNA folding stability. These characteristic features of IGSs also correlated significantly with 5'ETS variant patterns described previously and associated with differential expression of rDNA units. Our results suggest that variant rDNA units are differentially regulated and open a route to investigate the role of rDNA variation on nucleolar formation and possible associations with pathology.

Yoga in Lung Cancer Care: A Scoping Review of Randomized Clinical Trials and Outcomes

Background: Lung cancer, a leading cause of cancer-related morbidity and mortality worldwide, necessitates innovative therapeutic approaches to enhance patient outcomes. Yoga, an ancient practice with multifaceted benefits, has shown promise in cancer care but remains underexplored in lung cancer. Methods: This scoping review focused on randomized trials from 2014 to 2023, examining yoga interventions in lung cancer care. We conducted a comprehensive literature search across PubMed, Cochrane, Embase, and CINAHL. The selection involved screening for relevance and detailed data extraction on study characteristics. Results: The review identified three studies that met the inclusion criteria, highlighting notable benefits such as short term pulmonary enhancements, significant physical and social function improvements for patients and caregivers, and perioperative benefits such as reduced dyspnea and anxiety. Conclusion: Preliminary evidence suggests yoga could be a valuable adjunct therapy in lung cancer treatment. However, the heterogeneity in study designs and small sample sizes highlight the need for further, more rigorous research to establish standardized yoga protocols for lung cancer care.

International Cross-Temporal Meta-Analysis of Assortative Mating for Educational Attainment.

Previous studies have found a high degree of assortative mating for educational attainment (r = .56). However, this can be confounded by cohort effects or country effects, where certain nations may have more pronounced assortative mating than others. In addition, method variance regarding how educational attainment is measured may also result in heterogeneity of effect sizes. Effect sizes were gathered from various datasets and from academic literature, resulting in a large collection of effect sizes (k = 1498, n = 9,159,098), spanning 84 different countries. Assortative mating for educational attainment was stronger than what previous literature suggested (r = .66, [.64, .68]), largely due to the fact that assortative mating for educational attainment is stronger when latent methods are used. The strongest predictors of assortative mating for education between countries were individualism (r = -.61, p < .001) and HDI (r = -.56, p < .001). Assortative mating over time was found to vary by region. Capitalist Europe experienced an increase in assortative mating for education, while Communist Europe experienced a decrease. The United States had a non-linear trend in assortative mating for educational attainment, as it decreased from 1875 to 1926, increased from 1926 to 1945, decreased from 1945 to 1958, increased from 1958 to 1977, and decreased from 1977 onwards.

Fine quantitative characterization of high-H2S gas reservoirs under the influence of liquid sulfur deposition and adsorption

In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs, three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments. Fine quantitative characterization of the cores in three steady states (original, after sulfur injection, and after gas flooding) was carried out using the nuclear magnetic resonance (NMR) transverse relaxation time spectrum and imaging, X-ray computer tomography (CT) of full-diameter cores, basic physical property testing, and field emission scanning electron microscopy imaging. The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1 000 μm. Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces, and causes greater damage to reservoirs with poor original pore structures. The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics. The worse the pore structure, the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption, and the stronger the heterogeneity. Liquid sulfur deposition and adsorption change the pore size distribution, pore connectivity, and heterogeneity of the rock, which further changes the physical properties of the reservoir. After sulfur injection and gas flooding, the permeability of Type I reservoirs with good physical properties decreased by 16%, and that of Types II and III reservoirs with poor physical properties decreased by 90% or more, suggesting an extremely high damage. This indicates that the worse the initial physical properties, the greater the damage of liquid sulfur deposition and adsorption. Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence, cobweb, or retinitis, causing different changes in the pore structure and physical property of the reservoir.

Do Implant Coatings Affect Healing of Placed Implants? An Umbrella Review.

To analyze the available evidence and assess the effect of different implant coatings on healing outcomes. Using the PICOS strategy, a structured question was formed. A protocol was agreed upon and registered with PROSPERO (no. CRD42022321926). The MEDLINE, Embase, Cochrane Database of Systematic Reviews, Scopus, Web of Science, Pubmed, and ScienceDirect databases were searched using a structured strategy. Study selection was independently carried out in duplicate, first by title and abstract, then by full-text assessment. Quality and risk of bias were independently assessed in duplicate using AMSTAR 2 and ROBIS. Data extraction was independently undertaken in duplicate using a predefined extraction form. The search yielded 11 systematic reviews for inclusion. The most commonly assessed coatings were based on calcium phosphate-including hydroxyapatite (HA), brushite, and bioabsorbable nano-HA-followed by bisphosphonate, then bioactive glass coatings. Included reviews most frequently assessed marginal bone loss (MBL), bone-to-implant contact (BIC), and survival/success rates. There was considerable heterogeneity and small sample sizes. The quality assessment suggested low confidence in the reviews and high risk of bias. The included reviews provide weak evidence that implant coatings improve osseointegration and reduce MBL following implant placement. There was weak evidence for progressive complications for calcium phosphate coatings. Further research and long-term multicenter controlled clinical trials with improved standardization and control of bias are required to better understand the effects of coating implants.

THE IMPACT OF CORPORATE SOCIAL NETWORK ON INNOVATION PERFORMANCE - THE CHAIN MEDIATION EFFECT BASED ON KNOWLEDGE ACQUISITION AND ABSORPTIVE CAPACITY

Innovation is the lifeblood and inexhaustible driving force behind the development of an enterprise. With the continuous improvement of scientific and technological levels, the acceleration of technological change, and the changes in market demand, the complexity and uncertainty of innovation are increasing day by day. Enterprises have to acquire knowledge from outside, to obtain new impetus for enterprise development. The rich knowledge resources contained in corporate social networks provide a foundation for future innovation and development. This article takes Chinese enterprises as the research object and uses open innovation theory, social network theory, and knowledge management theory to construct a conceptual model of "social network-knowledge acquisition-absorptive capacity-innovation performance." Through empirical analysis of 549 valid questionnaires, it was found that networks do not all have a positive effect on enterprise innovation performance. This study shows that network size, network centrality, and network heterogeneity have a positive effect on innovation performance. The effect of network relationship strength on innovation performance is not significant. Knowledge acquisition and absorptive capacity play an important role in society. Network size, network centrality, and network heterogeneity have a chain-mediating role in their impact on corporate innovation performance.

Study on the causal relationship between educational attainment and delirium: A two-sample Mendelian randomization study

This study aimed to investigate whether there is a causal relationship between educational attainment and delirium at the genetic level using the Mendelian randomization method, and provide new evidence for studies in this field. We found a causal relationship between educational attainment and delirium at the genetic level after excluding confounders using Mendelian randomization. The inverse variance weighting method of random effects was the main analysis method. The weighted median and Mendelian Randomization-Egger methods, as well as simple, and weighted modes were used as supplementary analysis methods. Additionally, horizontal pleiotropy tests were conducted, including the Mendelian Randomization-Egger intercept test and Mendelian Randomization Pleiotropy RESidual Sum and Outlier. Cochran's Q statistic was used to assess the size of heterogeneity. We retrieved all second single nucleotide polymorphism features and performed multivariate Mendelian randomization to adjust for the effect of potential confounders on our results. The inverse variance weighting suggested a negative correlation between genetically predicted educational attainment and delirium (0.67[0.49–0.92], p = 0.013); Mendelian Randomization Pleiotropy RESidual Sum and Outlier (0.67[0.49–0.92], p = 0.013) and multivariate Mendelian randomization (0.52[0.33–0.82], p = 0.005) results were generally consistent with the inverse variance weighting method. The Mendelian Randomization-Egger, simple, and weighted mode results were consistent with the inverse variance weighting results. Our results were not affected by pleiotropy or heterogeneity (p > 0.05, for both pleiotropy and heterogeneity). In addition, the “leave-one-out” analysis showed that the results of our Mendelian randomization analysis were not influenced by individual single nucleotide polymorphisms. Studies have found a causal relationship between educational attainment and delirium at the genetic level; higher educational attainment may be a protective factor against delirium. Clinically, more attention should be paid to patients at a high risk of delirium with low educational attainment.

Is Formal Social Participation Associated with Cognitive Function in Middle-Aged and Older Adults? A Systematic Review with Meta-Analysis of Longitudinal Studies.

This systematic review with meta-analysis aimed to explore the association between formal social participation and cognitive function in middle-aged and older adults using data from longitudinal studies. A comprehensive search was conducted in Scopus, PubMed, and Web of Science for longitudinal studies that assessed the association between formal social participation and cognitive function in middle-aged and older adults published between January 2010 to 19 August 2022. Risk of bias was judged using the RoBANS tool. Meta-analysis using a random-effects model was computed with odds ratio (OR) and 95% confidence interval (CI) for cognitive decline probability. Sensitivity analyses were made to explore any changes to the pooled statistical heterogeneity and pooled effect size. Certainty of evidence was judged using the GRADE framework. We included 15 studies comprising 136,397 participants from 5 countries. Meta-analyses showed that formal social participation was associated with reduced cognitive decline (OR = 0.78, 95% CI 0.75-0.82, p < 0.001), with very low certainty of evidence. Formal social participation appears to enhance cognition in middle-aged and older adults, but further high-quality research is needed given the very low certainty of evidence.

Hysteretic water-retention behaviour of unsaturated hydrophobised soils

Hydrophobised soils found in the superficial region of earthen infrastructure can affect the hydrological processes of these structures. The hysteretic water-retention curve (WRC), which governs these processes, for hydrophobised soils has rarely been reported. Existing apparatus is unable to measure the WRC of unsaturated soils as it could not control the condition of pore water pressure (uw) in excess of pore air pressure (ua) when the contact angle was larger than 90°. In this study, a new apparatus was created, which sandwiches a soil sample between a high water-entry value (WEV) membrane and a high air-entry value (AEV) ceramic disc, to control the uw &lt; ua and uw &gt; ua conditions. Contact angle hysteresis and menisci evolution in the test materials during wet–dry cycles were measured to interpret the WRC. The WEV of soil increased with decreasing chemical heterogeneity and particle size. When drying the hydrophobised soils, they could retain water before reaching a certain negative uw. The WEV identified from the second wetting cycle was lower than that from the first cycle, whereas the AEV remained largely unchanged. The WEV and AEV decreased when the particle size of the hydrophobised materials was increased, resulting in a smaller hysteresis size.

Structural characterization and dielectric behavior of substituted bismuth niobate Bi17Nb3-4xV2xP2xO33 with fluorite-like structure

Structural, morphological, and dielectric properties of substituted bismuth niobates Bi17Nb3-4xV2xP2xO33 with a fluorite-like structure have been reported. The study focuses on substituting Nb5+ with V5+ and P5+ cations in Bi17Nb3O33. The resulting ceramics were synthesized using the solid-state reaction technique, and their crystal structure was analyzed using X-ray diffraction. The analysis confirmed the stabilization of the compounds in a single phase of a cubic fluorite structure. Structural refinement analysis has been performed for the compound Bi17Nb2.4V0.3P0.3O33 to investigate the details of the crystalline structure which was found to be a cubic fluorite structure at room temperature (space group Fm3‾m). Scanning Electron Microscopy (SEM) was used to examine the surface morphology of the samples, which exhibited irregular shapes and heterogeneous size distribution. The dielectric properties of the ceramics were analyzed, and the dielectric permittivity (ε’) and loss factor (tan δ) were measured at different frequencies and temperatures. The results showed anomalies in each frequency-dependent curve, indicating a relaxation phenomenon. The electrical conductivity (σ) of the ceramics was studied, and it was found that the conductivity displayed a frequency-independent plateau at low frequencies, indicating a semiconductor behavior. The complex impedance spectra and electrical modulus analysis were also conducted to investigate the relaxation processes in the material.

The sustainability of development pathways and climate change vulnerability in the Americas

Sustainability transformation requires societies to shift their development pathways to maintain ecological integrity and supply basic human needs over generations. We examine the sustainability of the development pathways of 351 national and sub-national geopolitical units in the Americas between 2001 and 2020. Then, we test the hypothesis that such pathways are influenced by land area, population size and topographic heterogeneity. Finally, we combine information about the sustainability of development pathways with population density and future climate change index to identify the Americas' socio-climatic hotspots. The Americas is a mosaic of geopolitical units following distinct development pathways. Most (74.3%) of the geopolitical units have, to date, followed unsustainable development pathways. Altogether, they represent 37.6% of the Americas' land area and are home to 83.3% of the Americas' population. Land area and topographic heterogeneity facilitate sustainable pathways, while population size constrains them. Climate change will affect all geopolitical units, but those with unsustainable development pathways, a high population density and high climate change index are expected to be particularly vulnerable and should be considered priorities for climate-resilient development programmes. There is a need for integrated place-based policies that strengthen ecological and socio-economic infrastructures to advance sustainable development pathways under changing climate conditions.

Overcoming the strength-ductility tradeoff of a 3D-printed Al-Si alloy by equal channel angular pressing

The integration of additive manufacturing and severe plastic deformation has produced an Al-Si alloy with superior mechanical properties. The novel processing pathway effectively avoids strength-ductility trade-off, resulting in an elongation increase of three times while maintaining a comparable yield strength to that of the original condition. The implementation of an intermediate annealing heat treatment (HT) before the subsequent equal channel angular pressing (ECAP) processing resulted in the most favorable combinations of strength and ductility. The ECAP process transformed the ultrafine interconnected eutectic network into ultrafine particles. This process also led to the formation of a heterogeneous grain size and the transformation of the 3-dimensional network of aluminides (Al2Cu) and Si-enriched precipitates into particles with varying sizes, ranging from 4 nm to 500 nm. In contrast, the ECAP processing without an intermediate annealing heat treatment led to a maximum yield strength increment of 22%. Notably, this enhancement in strength was achieved while preserving comparable levels of elongation to those observed in the as-built material. Hence, achieving the optimal combination of yield strength and ductility ratio demands a careful balance between various strengthening mechanisms, including subgrains and precipitates.

Too Many Meetings? Scheduling Rules for Team Coordination

Workers in knowledge-intensive industries often complain of having too many meetings, but organizations still give little thought to deciding when or how often to meet. We investigate the efficiency and robustness of various coordination scheduling rules. We consider workers who are engaged in a common activity (e.g., software programming) that can be divided into largely independent, parallel production tasks, but that necessitates periodic coordination. Coordination enables workers to address issues they have encountered in their independent work but takes time away from production. Using a stylized game-theoretic model, we show that small teams allow a more fluid, that is, worker-driven, approach to scheduling coordination, such as preemptive coordination (or production), under which any worker can impose coordination (or production). In larger teams this becomes inefficient. Several approaches can mitigate this effect. One option is to allocate the decision rights to produce or coordinate to the most productive worker. A more general version is to implement a voting-based scheme, where a minimum number of workers from a predetermined subset choose to coordinate. A third approach is to modify the preemptive coordination and production rules by adding time-based controls, to reserve some minimal amount of productive time or to enforce coordination after some point. Finally, a fixed-interval meeting schedule works well for very large teams. Our research helps formalize the tension between meeting (coordinating) and producing and indicates how to adapt team coordination scheduling rules to the degree of worker heterogeneity and team size. This paper was accepted by Jay Swaminathan, operations management. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2021.03227 .

A Closed Queueing Networks Approach for an Optimal Heterogeneous Fleet Size of an Inter-Facility Bulk Material Transfer System

A Closed Queueing Networks Approach for an Optimal Heterogeneous Fleet Size of an Inter-Facility Bulk Material Transfer System