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Introduction: Genes encoding catechol-O-methyl-transferase (COMT) and adenosine A2A receptor (ADORA2A) have been shown to influence cognitive performances and responses to caffeine intake during prolonged wakefulness. The rs4680 single-nucleotide polymorphism (SNP) of COMT differentiates on memory score and circulating levels of the neurotrophic factor IGF-1. This study aimed to determine the kinetics of IGF-1, testosterone, and cortisol concentrations during prolonged wakefulness under caffeine or placebo intake in 37 healthy participants, and to analyze whether the responses are dependent on COMT rs4680 or ADORA2A rs5751876 SNPs. Methods: In caffeine (2.5 mg/kg, twice over 24 h) or placebo-controlled condition, blood sampling was performed at 1 h (08:00, baseline), 11 h, 13 h, 25 h (08:00 next day), 35 h, and 37 h of prolonged wakefulness, and at 08:00 after one night of recovery sleep, to assess hormonal concentrations. Genotyping was performed on blood cells. Results: Results indicated a significant increase in IGF-1 levels after 25, 35, and 37 h of prolonged wakefulness in the placebo condition, in subjects carrying the homozygous COMT A/A genotype only (expressed in absolute values [±SEM]: 118 ± 8, 121 ± 10, and 121 ± 10 vs. 105 ± 7 ng/mL for A/A, 127 ± 11, 128 ± 12, and 129 ± 13 vs. 120 ± 11 ng/mL for G/G, and 106 ± 9, 110 ± 10, and 106 ± 10 vs. 101 ± 8 ng/mL for G/A, after 25, 35, and 37 h of wakefulness versus 1 h; p < 0.05, condition X time X SNP). Acute caffeine intake exerted a COMT genotype-dependent reducing effect on IGF-1 kinetic response (104 ± 26, 107 ± 27, and 106 ± 26 vs. 100 ± 25 ng/mL for A/A genotype, at 25, 35, and 37 h of wakefulness vs. 1 h; p < 0.05 condition X time X SNP), plus on resting levels after overnight recovery (102 ± 5 vs. 113 ± 6 ng/mL) (p < 0.05, condition X SNP). Testosterone and cortisol concentrations decreased during wakefulness, and caffeine alleviated the testosterone reduction, unrelated to the COMT polymorphism. No significant main effect of the ADORA2A SNP was shown regardless of hormonal responses. Conclusion: Our results indicated that the COMT polymorphism interaction is important in determining the IGF-1 neurotrophic response to sleep deprivation with caffeine intake (NCT03859882).

Improving understanding of Arctic ecosystem climate feedback and parameterization of models that simulate freeze-Thaw dynamics require advances in quantifying soil and snow properties. Due to the significant spatiotemporal variability of soil properties and the limited information provided by point-scale measurements (e.g., cores), geophysical methods hold potential for improving soil and permafrost characterization. In this study, we evaluate the use of a ground-penetrating radar (GPR) to estimate thaw layer thickness, snow depth, and ice-wedge characteristics in an ice-wedge-dominated tundra region near Barrow, AK, USA. To this end, we analyze GPR and point-scale measurements collected along several parallel transects at the end of the growing season and the end of frozen season. In addition, we compare the structural information extracted from the GPR data with electrical resistivity tomography (ERT) information about ice-wedge characteristics. Our study generally highlights the value of GPR data collected in the frozen season, when conditions lead to the improved GPR signal-To-noise ratio, facilitate data acquisition, and reduce acquisition-related ecosystem disturbance relative to growing season. We document for the first time that GPR data collected during the frozen season can provide reliable estimates of active layer thickness and geometry of ice wedges. We find that the ice-wedge geometry extracted from GPR data collected during the frozen season is consistent with ERT data, and that GPR data can be used to constrain the ERT inversion. Consistent with recent studies, we also find that GPR data collected during the frozen season can provide good estimates of snow thickness, and that GPR data collected during the growing season can provide reliable estimate thaw depth. Our quantification of the value of the GPR and ERT data collected during growing and frozen seasons paves the way for coupled inversion of the datasets to improve understanding of permafrost variability.

Background: Ballet, epitomized by iconic seasonal performances such as "The Nutcracker," combines artistic expression with considerable physical demands. This study investigated the physiological and psychological responses of ballet dancers to the demands of intensive training and performance, with a specific focus on "The Nutcracker." Methods: Thirty- eight dancers volunteered for the study, including 6 youths (10.5 + 1.8 years, n = 6 female), 7 adolescents (15.4 + 1.1 years, n = 5 female), and 25 adults (21.1 + 2.1 years, n = 20 female). Employing an uncontrolled observational design, this pilot study tracked key biomarkers such as CK-MM for muscle damage and B-ALP for bone health, alongside psychological measures via PANAS-C/PANAS and DASS-21. Results: Significant findings included a post-performance reduction in cortisol and depression levels. Conclusion: These insights advocate for tailored strategies that address the multifaceted needs of dancers, acknowledging the intricate balance required to maintain peak performance and overall health within the demanding realm of professional ballet. [ABSTRACT FROM AUTHOR]

Greater increases in negative affect and greater decreases in positive affect on days stressors occur portend poorer mental and physical health years later. Although personality traits influence stressor-related affect, only neuroticism and extraversion among the Big Five personality traits have been examined in any detail. Moreover, personality traits may shape how people appraise daily stressors, yet few studies have examined how stressor-related appraisals may account for associations between personality and stressor-related affect. Two studies used participants (N = 2,022; age range: 30-84) from the National Study of Daily Experiences II to examine the associations between Big Five personality traits and stressor-related affect and how appraisals may account for these relationships. Results from Study 1 indicate that higher levels of extraversion, conscientiousness, and openness to experience and lower levels of neuroticism are related to less stressor-related negative affect. Only agreeableness was associated with stressor-related positive affect, such that higher levels were related to greater decreases in positive affect on days stressors occur. The second study found that stressor-related appraisals partially accounted for the significant associations between stressor-related negative affect and personality. Implications for these findings in relation to how personality may influence physical and emotional health are discussed. (PsycINFO Database Record

Research on plant-pollinator interactions requires a diversity of perspectives and approaches, and documenting changing pollinator-plant interactions due to declining insect diversity and climate change is especially challenging. Natural history collections are increasingly important for such research and can provide ecological information across broad spatial and temporal scales. Here, we describe novel approaches that integrate museum specimens from insect and plant collections with field observations to quantify pollen networks over large spatial and temporal gradients. We present methodological strategies for evaluating insect-pollen network parameters based on pollen collected from museum insect specimens. These methods provide insight into spatial and temporal variation in pollen-insect interactions and complement other approaches to studying pollination, such as pollinator observation networks and flower enclosure experiments. We present example data from butterfly pollen networks over the past century in the Great Basin Desert and Sierra Nevada Mountains, United States. Complementary to these approaches, we describe rapid pollen identification methods that can increase speed and accuracy of taxonomic determinations, using pollen grains collected from herbarium specimens. As an example, we describe a convolutional neural network (CNN) to automate identification of pollen. We extracted images of pollen grains from 21 common species from herbarium specimens at the University of Nevada Reno (RENO). The CNN model achieved exceptional accuracy of identification, with a correct classification rate of 98.8%. These and similar approaches can transform the way we estimate pollination network parameters and greatly change inferences from existing networks, which have exploded over the past few decades. These techniques also allow us to address critical ecological questions related to mutualistic networks, community ecology, and conservation biology. Museum collections remain a bountiful source of data for biodiversity science and understanding global change.

Abstract Soil specialists can have restricted distributions, and effective management in the face of land use change depends on a thorough understanding of the ecology of these unique plants. We investigated the ecology of Eriogonum tiehmii Reveal, a rare soil specialist, using pitfall traps, flower observations, and pollinator exclusion to assess arthropod communities in E. tiehmii habitat, the most common visitors to E. tiehmii flowers, and the importance of pollination for seed set. We collected soil from 21 occupied and unoccupied sites for analysis of physical and chemical characteristics, and conducted a greenhouse soil preference experiment to test how seeds and seedlings respond to soil variation. We also monitored tagged plants in extant populations, measuring survival, size, and reproductive output. Arthropod communities within and around E. tiehmii sites were abundant and diverse; each sample site contained numerous unique species, and there was high turnover in arthropod community composition over time. Open pollination significantly increased seed production, with beetles, wasps, and flies the most likely important pollinators. Reproductive output and size class distributions varied among wild populations, and soil properties differed between occupied and unoccupied sites. Occupied sites were, on average, lower in sulfur, zinc, potassium, and magnesium and, on average higher in boron, pH, and silt, among other differences, though there was high variation in these characteristics among sites. Seedlings demonstrated sensitivity to individual soil properties, and seedlings grown in soils from occupied sites had, on average, higher total biomass and higher root allocation than seedlings grown in soils from unoccupied sites. These preference tests suggest a “specialist” model of soil specialization rather than a “refuge” model, indicating that plants are not simply highly stress‐tolerant, but are specifically adapted to their native soil types. While some unoccupied sites we tested were favorable for some life history stages, we did not identify unoccupied sites that could support both establishment and growth of E. tiehmii seedlings. Future work could consider the effects of biotic interactions such as plant competition and herbivores on plant growth, and employ additional demographic monitoring to better understand life history and population dynamics of this extreme soil specialist.

The authors describe a 61-year-old male patient with two previous melanoma who developed a pigmented lesion on a tattoo that was difficult to diagnose on dermoscopy but histopathology revealed the third melanoma with 0.3 mm thickness. The authors call the attention to increasing incidence of melanoma in the German population in parallel with the increase in tattooing, which may delay the diagnosis of melanoma in tattooed skin. Therefore, they recommend performing early biopsies in pigmented lesions in tattoos, especially before laser treatment of tattoos.

As part of a class, students read, discussed, and wrote about the book Strangers in Their Own Land: Anger and Mourning on the American Right by Arlie Hochschild. The following essay represents their collective thoughts and answers to three reflective prompts about empathy walls, one of the central themes of the book, and their role and importance in civil conversation.

This paper reports on the effects of a graduate course on teaching and learning on graduate teaching assistants' conceptions of teaching and on the teaching philosophy statements that arose from those conceptions. Effects are interpreted from three perspectives: 1) course facilitators' reports of their perceptions of course participants' conceptual change; 2) an independent assessors' ratings of the evidence of change through blind review of course participants' initial philosophy statements and final statements; and 3) participants' own perceptions of change and identification of the course components and learning activities that were most significant in their conceptual development. Findings suggest that graduate teaching assistants' perceptions of conceptual change differ significantly from those of both the course facilitators and the independent assessor.

Abstract A major complication of feminizing genitoplasty in children is the loss of clitoral sensation with serious impact at adult life. We suggest a new method to evaluate the surgical results during childhood based on the bulbocavernosus or clitoro-perineal reflex (CPR). The afferent pathway of CPR implies the intact sensory receptors on the clitoral glans. Girls with congenital adrenal hyperplasia who were followed-up medically without surgery or who underwent feminizing genitoplasty with or without clitoroplasty were included (2002–2018). All clitoroplasties were standardized reduction clitoroplasty with preservation of neurovascular bundles associated with vaginoplasty and vestibuloplasty. Standardized examinations were prospectively performed including the CPR starting at one year postoperatively. The reflex was triggered by gentle touch of the glans by a cotton swab. Contraction of the perineal muscles was considered positive. Thirty-two children were operated at a median age of 8.6 months (5.8–12.1). Median follow-up (FU) was 3.9 years (1.3–6.4). Twenty-four patients had clitoroplasties: 17 were tested for CPR at one-year FU, and all had a positive test. Eight girls had genitoplasty without clitoral surgery, two of them were tested and were positive. Ten patients were managed without surgery, two of them were tested for the CPR and were positive. The reflex was always triggered easily and repeated at least twice during the FU. The clitoro-perineal reflex is a simple, non-invasive and reproducible test in early childhood and may serve as an early evaluation tool of clitoral innervation after feminizing genitoplasty. These results need to be confirmed at long term and completed at adult life.

Contribution: A novel multidisciplinary undergraduate course on alternative energy (AE) engineering that addresses gaps in current AE education, provides hands on skills, and matches topical coverage with societal needs. Background: Resource depletion and emissions associated with burning fossil fuels have led to growing worldwide interest in electricity production from non-fossil fuel, or alternative, energy sources. Recently there has been rapid growth of AE sources such as wind and solar photovoltaics. Societal and economic factors contribute to this continuing trend. Recent research has shown the urgent need for structured AE course curricula; engineering education in this multidisciplinary field is essential to support continued growth in this field. Intended Outcomes: A new approach to AE engineering education at the undergraduate level. Specifically, a comprehensive multidisciplinary approach that fills identified gaps in AE education. Application Design: The design of the course includes lectures, laboratories, and a hybrid power system design project focusing on economic integration of AE in power systems. Topics include principles of energy conversion, energy storage, and integration of solar thermal, solar photovoltaic, wind, hydroelectric and fuel cell AE sources into power systems. Societal needs are addressed through focus on industry structure, technology, economics and policies pertaining to AE. Findings: Learning outcome assessment demonstrate the validity of the proposed course for multidisciplinary alternative energy engineering education.

The ability to efficiently produce and manipulate nonclassical states of light is a critical requirement for the development of quantum optical technologies. In recent years, experiments have demonstrated that cascaded spontaneous parametric down-conversion is a promising approach to implement photon precertification, providing a way to overcome photon transmission losses for quantum communication, as well as to directly produce entangled three-photon states and heralded Bell pairs. However, the low efficiency of this process has so far limited its applicability beyond basic experiments. Here, we propose a scheme to amplify triplet production rates by using a fast switch and a delay loop to reuse photons that fail to convert on the first pass through the cascade's second nonlinear crystal. We construct a theoretical model to predict amplification rates and verify them in an experimental implementation. Our proof-of-concept device increases the rate of detected photon triplets as predicted, demonstrating that the method has the potential to dramatically improve the usefulness of cascaded down-conversion for device-independent quantum communication and entangled state generation.

Objective: The Hong Kong Healthy Schools Award Scheme (HKHSA) developed an assessment and monitoring system to examine the status of Health Promoting Schools (HPS). This study made use of the HKHSA programme to investigate the school health 'profile' and student health status of four gold award schools following 3-4 years' participation in the scheme. Design: Repeated cross-sectional student health surveys of the same year level (Secondary 3) were conducted over different time periods, and achievement of HKHSA was assessed by repeated assessments of the school health profile using HPS indicators. Setting: This study included four schools with the Healthy School gold award in Hong Kong, together with students from three of the four schools. Methods: School performance in the six HPS key areas were analysed using radial plot graphs, and students' health behaviours were measured by means of repeated cross-sectional student health surveys. Results: The four gold award schools demonstrated various degrees of achievement in different HPS key areas with student health behaviours markedly improving in these schools. Further analyses revealed how certain HPS key area components were associated with sustained positive health behaviours among students. Conclusion: The ongoing implementation of HPS impacts on schools' environment and students' health behaviours. The HKHSA is designed for formative and summative assessment of school health promotion. Findings provide insight into an HPS assessment process, signalling future directions for the development of school health promotion.

Hospitals are exposed to abundant contamination sources with limited remediation strategies. Without new countermeasures or treatments, the risk of health care-associated infections will remain high. This study explored the impact of advanced photohydrolysis continuous disinfection technology on hospital environmental bioburden. Two acute care intensive care units in different locations (ie, Kentucky, Louisiana) during different time periods were sampled every 4 weeks for 4 months for colony-forming units (CFUs) of methicillin-resistant Staphylococcus aureus (MRSA) and fungi on surfaces and floors and fungi and aerobic bacteria in the air. At both sites, surface testing showed greater than 98% reduction in mean fungi and MRSA CFUs. Floor results had reductions by more than 96% for fungi and MRSA at both sites. Aerobic bacterial air and fungal CFUs had reductions up to 72% and 89%, respectively. HAIs declined 70% when postactivation data were compared to preactivation data. The continuous nature of advanced photohydrolysis decontamination, its ability to be used in occupied rooms, and its independence of human resources provide an innovative intervention for complex health care environments. This study is on the pioneering edge of demonstrating that continuous decontamination can reduce surface, floor, and air contamination and thereby reduce the acquisition of HAIs. • Environmental contamination is continuous and contributes to infection risk. • Advanced photohydrolysis technology recreates photolysis to neutralize pathogens. • This technology provides decontamination that is continuous and persistent. • Results showed surface and air bioburdens were reduced up to 99%. • Health care-associated infections (HAIs) observed a greater than 70% decline. [ABSTRACT FROM AUTHOR]

Abstract Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common garden study to quantify variation in growth and drought resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high integrated water use efficiency (δ13C). Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and low δ13C. Irrespective of climate, we also observed trade‐offs between biomass production and drought resistance traits. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. In addition, ecotypes that grow rapidly may be less able to persist under dry conditions. Land managers may be able to use this variation to improve restoration success by seeding ecotypes with multiple drought resistance traits in areas with lower precipitation. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions.

This study presents the first detailed glacial geomorphological map of the sediment-landform assemblages formed by three eastern outlet glaciers of the former Patagonian Ice Sheet. These glaciers occupied the Río Corcovado, Río Huemul and Lago Palena/General Vintter valleys, Chubut province, Argentina (43°S, 71°W). By combining remote sensing and field-mapping, we build on previous ice-sheet scale mapping and geological surveys to provide high-resolution spatial information on local ice-contact glaciogenic, glaciofluvial, glaciolacustrine, and subglacial landforms. Twenty-five landform types, many of which are newly mapped in the region, were digitized as georeferenced shapefiles over a 5300 km2 area. This map enables the identification of former ice-flow directions, relative ice-margin positions and glaciofluvial drainage pathways for each preserved Quaternary glaciation. It also elucidates the former areal extent, geolocation and spillways of glaciolacustrine bodies formed during the last deglaciation. The map delivers an essential framework on which to build robust glacier-scale geomorphological and geochronological reconstructions.

Abstract Trait–environment correlations can arise from local adaptation and can identify genetically and environmentally appropriate seeds for restoration projects. However, anthropogenic changes can disrupt the relationships between traits and fitness. Finding the best seed sources for restoration may rely on describing plant traits adaptive in disturbed and invaded environments, recognizing that while traits may differ among species and functional groups, there may be similarities in the strategies that increase seedling establishment. Focusing on three grass genera, two shrub species, and two forb genera, we collected seeds of all taxa from 16 common sites in the sagebrush steppe of the western United States. We measured seed and seedling characteristics, including seed size, emergence timing, and root and shoot traits, and compiled a suite of environmental variables for each collection site. We described trait–environment associations and asked how traits or environment of origin were associated with seedling survival in invaded gardens. Sampling seven taxa from the same sites allowed us to ask how trait–environment–performance associations differ among taxa and whether natural selection favors similar traits across multiple taxa and functional groups. All taxa showed trait–environment associations consistent with local adaptation, and both environment of origin and phenotypes predicted survival in competitive restoration settings, with some commonalities among taxa. Notably, rapid emergence and larger seeds increased survival for multiple taxa. Environmental factors at collection sites, including lower slopes (especially for grasses), greater mean annual temperatures (especially for shrubs and forbs), and greater precipitation seasonality were frequently associated with increased survival. We noted one collection site with high seedling survival across all seven taxa, suggesting that conditions within some sites may result in selection for traits that increase establishment for multiple species. Thus, choosing native plant sources with the most adaptive traits, along with matching climates, will likely improve the restoration of invaded communities.

Rhodopsin-associated (RHO-associated) retinitis pigmentosa (RP) is a progressive retinal disease that currently has no cure. RHO protein misfolding leads to disturbed proteostasis and the death of rod photoreceptors, resulting in decreased vision. We previously identified nonretinoid chaperones of RHO, including YC-001 and F5257-0462, by small-molecule high-throughput screening. Here, we profile the chaperone activities of these molecules toward the cell-surface level of 27 RP-causing human RHO mutants in NIH3T3 cells. Furthermore, using retinal explant culture, we show that YC-001 improves retinal proteostasis by supporting RHO homeostasis in RhoP23H/+ mouse retinae, which results in thicker outer nuclear layers (ONL), indicating delayed photoreceptor degeneration. Interestingly, YC-001 ameliorated retinal immune responses and reduced the number of microglia/macrophages in the RhoP23H/+ retinal explants. Similarly, F5257-0462 also protects photoreceptors in RhoP23H/+ retinal explants. In vivo, intravitreal injection of YC-001 or F5257-0462 microparticles in PBS shows that F5257-0462 has a higher efficacy in preserving photoreceptor function and delaying photoreceptor death in RhoP23H/+ mice. Collectively, we provide proof of principle that nonretinoid chaperones are promising drug candidates in treating RHO-associated RP.

UnlabelledWearing contact lenses has been identified as a risk factor for the development of eye conditions such as giant papillary conjunctivitis and keratitis. We hypothesized that wearing contact lenses is associated with changes in the ocular microbiota. We compared the bacterial communities of the conjunctiva and skin under the eye from 58 subjects and analyzed samples from 20 subjects (9 lens wearers and 11 non-lens wearers) taken at 3 time points using a 16S rRNA gene-based sequencing technique (V4 region; Illumina MiSeq). We found that using anesthetic eye drops before sampling decreases the detected ocular microbiota diversity. Compared to those from non-lens wearers, dry conjunctival swabs from lens wearers had more variable and skin-like bacterial community structures (UniFrac;P value = 3.0). The results indicate that wearing contact lenses alters the microbial structure of the ocular conjunctiva, making it more similar to that of the skin microbiota. Further research is needed to determine whether the microbiome structure provides less protection from ocular infections.ImportanceAs in other body sites (i.e., the gut, skin, and mouth), the eye has a normal community of bacteria which are expected to confer resistance that provides protection from invaders. However, the eye microbiome has been largely neglected and is relevant to eye health and understanding eye diseases and to discovery of its functions. This report of a baseline study shows differences in the eye microbiome of contact lens wearers in relation to those of non-lens wearers and has the potential to help future studies explore novel insights into a possible role of the microbiome in the increased risk for eye infections in contact lens wearers.

The association between multiple pilomatricomasand the autosomal dominant neurodegenerativedisorder myotonic dystrophy has been described inthe literature. Although the mechanism is unknown,it is hypothesized that the dystrophia myotonicaprotein kinase mutation in myotonic dystrophyaffects intracellular calcium levels, which alterproliferation and terminal differentiation that leads tocells that are observed in pilomatricomas. We presenta patient with multiple, symptomatic pilomatricomasand myotonic dystrophy, with a strong family historyof both of these rare disorders.

We report a 68-year-old woman with chroniclymphocytic leukemia, who developed numerous,pruritic, edematous, and vesicobullous skin lesionsof the face and extremities over the course of severalmonths. The diagnosis of eosinophilic dermatosis ofhematologic malignancy (EDHM) was made basedon the clinical history and histopathologic features.Owing to the possible link between EDHM and amore aggressive underlying CLL, she was startedagain on chemotherapy. This case serves as areminder that, although the precise pathogenesis ofEDHM remains unclear, the paraneoplastic disorderis the result of immune dysregulation. Patientswho develop EDHM should undergo prompthematologic/oncologic evaluation.

Perniosis is a localized, inflammatory reaction that ischaracterized by erythematous papules and nodulesthat often are located on the acral surfaces in youngwomen. The lesions of perniosis are thought to bedue to cold-induced vasoconstriction that leadsto hypoxemia and inflammation of the vessel wall.Histopathologic and laboratory studies are indicatedfor patients with suspected perniosis to distinguishbetween idiopathic perniosis and secondaryperniosis. Treatment includes adequate heating andclothing, proper food intake, nifedipine, ultravioletA1 phototherapy, topical glucocorticoids, andvasodilators.

In this paper we report on research we conducted to begin the process of identifying threshold concepts in the field of postsecondary teaching. Meyer & Land (2006) propose that within all disciplinary fields there seem to be particular "threshold concepts" that serve as gateways, opening up new and previously inaccessible ways of thinking and practicing. We developed a series of questions focusing on the "troublesome" and "transformative" characteristics of threshold concepts and asked these questions of several constituent groups, including those who are new to practice and the body of knowledge in postsecondary teaching and those who are already knowledgeable and/or experienced in the field. Based on our interpretation of participants' responses, we identified four recognized concepts in the field of postsecondary teaching as potential threshold concepts in this field: Assessment "for/as" learning; Learning-centred teaching; Accommodation for diversity; and, Context-driven practice. Our findings suggest that threshold concepts are relevant to the field of postsecondary teaching. Through this work, we hope to help educational developers and faculty members consider what is involved in learning to teach and developing teaching expertise, and to encourage critical discussion about the teaching development "curriculum" in postsecondary settings. Threshold concepts arise as a field develops and are defined as practitioners and scholars in the field define their field. At this stage, we believe the real value of threshold concepts for postsecondary teaching lies in the discussion that arises in the process of identifying and naming the concepts.