About merging threshold and critical flux concepts into a single one: the boundary flux.
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ABSTRACT:
SUBMITTER: Stoller M
PROVIDER: S-EPMC3925542 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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Project description:Threshold concepts (TCs) are concepts that, when mastered, represent a transformed understanding of a discipline without which the learner cannot progress. We have undertaken a process involving more than 75 faculty members and 50 undergraduate students to identify a working list of TCs for biochemistry. The process of identifying TCs for biochemistry was modeled on extensive work related to TCs across a range of disciplines and included faculty workshops and student interviews. Using an iterative process, we prioritized five concepts on which to focus future development of instructional materials. Broadly defined, the concepts are steady state, biochemical pathway dynamics and regulation, the physical basis of interactions, thermodynamics of macromolecular structure formation, and free energy. The working list presented here is not intended to be exhaustive, but rather is meant to identify a subset of TCs for biochemistry for which instructional and assessment tools for undergraduate biochemistry will be developed.
| S-EPMC4152212 | biostudies-literature
Project description:IntroductionThe threshold concept framework (TCF) was first described nearly 20 years ago, but its application in the field of medical education has recently seen a significant growth of interest with a diverse range of literature published on the subject. The transformative nature of threshold concepts (TCs) offers potential for the design of learning experiences and curricula across the medical education continuum. A scoping review was conducted to map the extent of the current literature regarding TCs in medical education-to describe the types of available evidence and its focus-and identify research gaps.MethodsThe review followed the JBI Manual for Evidence Synthesis approach for scoping reviews. Four databases and two additional websites were searched for articles exploring TCs in medical education. Data were analysed using quantitative and qualitative thematic approaches. A framework of conceptual change was used to synthesise the TCs identified.ResultsThirty-six papers, spanning undergraduate, postgraduate and continuing medical education, were included in the final analysis. The most frequent application of the TCF was in the identification of TCs, which related to basic scientific knowledge, ways of thinking and ways of practising in medicine. Uncertainty, patient care, clinical reasoning and professional identify formation were themes that emerged at multiple stages of training. Several papers evaluated the use of the TCF in teaching.ConclusionThe understanding and embodiment of TCs increases in complexity across the medical education continuum, with TCs recurring with changes in clinical environment and responsibilities. This lends support to a holistic approach to curriculum design spanning all stages of training. Further research is needed to develop a consistent approach for describing and applying the TCF in medical education and to address how the TCF can be used in teaching and how threshold crossing can be measured.
| S-EPMC9543879 | biostudies-literature
Project description:Threshold concepts (TCs) are increasingly used in health professions education (HPE) research. TCs are claimed to be conceptual gateways which are often traversed with substantial difficulty. In this paper, we report on a scoping review investigating the following research question: What is the scope and nature of the currently available research on threshold concepts in health professions education literature? We employed Arksey and O'Malley's model for scoping reviews. A search for literature on TCs in HPE research between 2003 and 2020 yielded 999 records of which 59 were included in the review. The data set was subject to quantitative descriptive analysis of article characteristics as well as qualitative thematic analysis of the scope of research on TCs. Among the 59 articles selected for review, there were 30 empirical, 26 conceptual and three reviews. A majority were published in 2015 or later. Almost half of the included articles attempted to identify possible TCs within HPE. Others investigated how TCs can be traversed or suggested how TCs could influence curriculum design. Some critically appraised the framework of TC. Although TCs are increasingly utilised in HPE, the present review identified how researchers came across methodological challenges related to identifying possible TCs and definitional challenges around identifying the essential characteristics of TCs. Before embracing TCs as the next go-to theory for learning in HPE, we acknowledge the need for methodological stringeny and rigour as well as more data to support TCs. Until then, any implementation of TCs in HPE curricula should be done cautiously.
| S-EPMC9859919 | biostudies-literature
Project description:IntroductionBlood lactate concentration rises exponentially during graded exercise when muscles produce more lactate than the body can remove, and the blood lactate-related thresholds are parameters based on this curve used to evaluate performance level and help athletes optimize training. Many different concepts of describing such a threshold have been published. This study aims to compare concepts for their repeatability and predictive properties of endurance performance.MethodsForty-eight well-trained male cyclists aged 18-50 performed 5 maximal graded exercise tests each separated by two weeks. Blood lactate-related thresholds were calculated using eight different representative concepts. Repeatability of each concept was assessed using Cronbach's alpha and intra-subject CV and predictive value with 45 minute time trial tests and a road race to the top of Mont Ventoux was evaluated using Pearson correlations.ResultsRepeatability of all concepts was good to excellent (Cronbach's alpha of 0.89-0.96), intra-subject CVs were low with 3.4-8.1%. Predictive value for performance in the time trial tests and road race showed significant correlations ranging from 0.65-0.94 and 0.53-0.76, respectively.ConclusionAll evaluated concepts performed adequate, but there were differences between concepts. One concept had both the highest repeatability and the highest predictability of cycling performance, and is therefore recommended to be used: the Dmax modified method. As an easier to apply alternative, the lactate threshold with a fixed value of 4 mmol/L could be used as it performed almost as well.Trial registrationDutch Trial Registry NTR5643.
| S-EPMC6235347 | biostudies-literature
Project description:Students' metacognitive skills and perceptions are considered important variables for high-quality learning. In this study, students' perceptions were used to identify histological threshold concepts (integrative, irreversible, transformative, and troublesome) in three health sciences curricula. A specific questionnaire was developed and validated to characterize students' perceptions of histological threshold concepts. A sample of 410 undergraduate students enrolled in the dentistry, medicine, and pharmacy degree programs participated in the study. Concepts assessed in the study were clustered to ten categories (factors) by exploratory and confirmatory factor analysis. Concepts linked to tissue organization and tissue functional states received the highest scores from students in all degree programs, suggesting that the process of learning histology requires the integration of both static concepts related to the constituent elements of tissues and dynamic concepts such as stem cells as a tissue renewal substrate, or the euplasic, proplasic and retroplasic states of tissues. The complexity of integrating static and dynamic concepts may pose a challenging barrier to the comprehension of histology. In addition, several differences were detected among the students in different degree programs. Dentistry students more often perceived morphostructural concepts as threshold concepts, whereas medical students highlighted concepts related to two-dimensional microscopic identification. Lastly, pharmacy students identified concepts related to tissue general activity as critical for the comprehension and learning of histology. The identification of threshold concepts through students' perceptions is potentially useful to improve the teaching and learning process in health sciences curricula.
| S-EPMC10078720 | biostudies-literature
Project description:TRPV1 plays an important role in the thermosensory system; however, the mechanism controlling its heat activation property is not well understood. Here, we determine the heat activation properties of TRPV1 cloned from tailed amphibians, which prefer cooler environments, finding the threshold temperatures were approximately 10 °C lower compared with rat TRPV1 (rTRPV1). We find that two amino acid residues (Gln, Leu/Val) in the Ankyrin Repeat 1 (ANK1) region of the N-terminal domain are conserved among tailed amphibians and different from those (Arg, Lys) in rTRPV1. We observe the activation by heat in all urodelan TRPV1s is markedly elevated by substitution of these two amino acids. Conversely, reciprocal substitutions of rTRPV1 apparently lowers the high threshold temperature. Our studies demonstrate that tailed amphibians express TRPV1 with a reduced heat-activation threshold by substitution of two amino acid residues in the ANK1 region that likely contribute to cool-habitat selection.
| S-EPMC10175561 | biostudies-literature
Project description:Wind has been an enduring geologic agent throughout the history of Mars, but it is often unclear where and why sediment is mobile in the current epoch. We investigated whether eolian bed-form (dune and ripple) transport rates are depressed or enhanced in some areas by local or regional boundary conditions (e.g., topography, sand supply/availability). Bedform heights, migration rates, and sand fluxes all span two to three orders of magnitude across Mars, but we found that areas with the highest sand fluxes are concentrated in three regions: Syrtis Major, Hellespontus Montes, and the north polar erg. All regions are located near prominent transition zones of topography (e.g., basins, polar caps) and thermophysical properties (e.g., albedo variations); these are not known to be critical terrestrial boundary conditions. The two regions adjacent to major impact basins (Hellas and Isidis Planitia) showed radially outward upslope winds driving sand movement, although seasonally reversing wind regimes were also observed. The northern polar dunes yielded the highest known fluxes on the planet, driven by summer katabatic winds modulated by the seasonal CO2 cap retreat-processes not known to affect terrestrial dunes. In contrast, southern dune fields (<45°S) were less mobile, likely as a result of seasonal frost and ground ice suppressing sand availability. Results suggest that, unlike on Earth, large-scale topographic and thermophysical variabilities play a leading role in driving sand fluxes on Mars.
| S-EPMC7241575 | biostudies-literature
Project description:Background. Threshold concepts are key to professional identity development, transforming the way individuals think, act, and perceive the world. Purpose. To understand how occupational therapy students describe their professional identity, its importance, and how threshold concepts contribute to identity. Method. Mixed-method survey of final-year occupational therapy students (n = 58) at an Australian University. Findings. (i) High agreement on most identity and threshold questions; but up to 24% uncertain about confidence/competence in understanding specific concepts; (ii) occupation-focus is unique to our professional identity; (ii) identity develops over time; (iii) occupation-based, client-centered, and evidence-based practices are central to thinking like and becoming an occupational therapist; and (iv) practice education provides context for threshold concepts to be transformative. Implications. Identity is defined by a focus on occupation and its relationship to health. Traversing threshold concepts through academic and practice education is essential to developing professional identity.
| S-EPMC10647904 | biostudies-literature
Project description:BackgroundHematopoiesis is a complex process involving different cell types and feedback mechanisms mediated by cytokines. This complexity stimulated various models with different scopes and applications. A combination of complementary models promises to provide their mutual confirmation and to explain a broader range of scenarios. Here we propose a combination of an ordinary differential equation (ODE) model of human granulopoiesis and an agent-based model (ABM) of hematopoietic stem cell (HSC) organization. The first describes the dynamics of bone marrow cell stages and circulating cells under various perturbations such as G-CSF treatment or chemotherapy. In contrast to the ODE model describing cell numbers, our ABM focuses on the organization of individual cells in the stem population.ResultsWe combined the two models by replacing the HSC compartment of the ODE model by a difference equation formulation of the ABM. In this hybrid model, regulatory mechanisms and parameters of the original models were kept unchanged except for a few specific improvements: (i) Effect of chemotherapy was restricted to proliferating HSC and (ii) HSC regulation in the ODE model was replaced by the intrinsic regulation of the ABM. Model simulations of bleeding, chronic irradiation and stem cell transplantation revealed that the dynamics of hybrid and ODE model differ markedly in scenarios with stem cell damage. Despite these differences in response to stem cell damage, both models explain clinical data of leukocyte dynamics under four chemotherapy regimens.ConclusionsABM and ODE model proved to be compatible and were combined without altering the structure of both models. The new hybrid model introduces model improvements by considering the proliferative state of stem cells and enabling a cell cycle-dependent effect of chemotherapy. We demonstrated that it is able to explain and predict granulopoietic dynamics for a large variety of scenarios such as irradiation, bone marrow transplantation, chemotherapy and growth factor applications. Therefore, it promises to serve as a valuable tool for studies in a broader range of clinical applications, in particular where stem cell activation and proliferation are involved.
| S-EPMC4228322 | biostudies-literature
Project description:ObjectiveTo identify threshold concepts (TCs) for physicians undergoing postgraduate medical education (PGME) in general practice.DesignAn explorative, qualitative study with 65 min focus group interviews and thematic analysis was used. Participants were asked to describe their most transformative learning experiences. Heuristical TCs were identified from the thematic analysis.SettingAotearoa/New Zealand (A/NZ).ParticipantsFifty participants, mostly comprising current trainees and educators from urban centres, and of NZ/European ethnicity.ResultsTwenty TCs covering many aspects of postgraduate general practice experience were derived from themes identified in the data. Presented in medical proverbial form for ease of recollection, these included: Money makes the practice go round; Be a legal eagle; Manage time or it will manage you; Guidelines, GPs' little helpers; Right tool, right word, right place; The whole of the practice is greater than the sum of the parts; The personal enhances the professional; Beat biases by reflection; Chew the Complexity, Unpredictability, Diversity; Embrace the uncertainty; Not knowing is knowing; Seek and you shall find; Waiting and seeing, waiting and being; Look, listen, think between the lines; Treat the patient beyond the disease; No patient is an island; Words work wonders; Hearing is healing; Being you and being there; and; The relationship is worth a thousand consults. These TCs mapped onto core competencies in A/NZ's PGME in general practice curriculum.ConclusionsParticipants readily identified transformative and troublesome moments in their PGME in general practice. These findings confirmed evidence for a wide range of TCs with many newly identified in this study. All TCs were fundamentally based on the doctor-patient relationship, although often involving the context and culture of general practice. Actively incorporating and teaching these identified TCs in PGME in general practice may enable trainees to grasp these important learning thresholds earlier and more easily and aid in identity and role formation.
| S-EPMC9207916 | biostudies-literature