ABSTRACT
INTRODUCTION: Professional identity formation (PIF) is a central tenet of effective medical education. However, efforts to support, assess and study PIF are hindered by unclear definitions and conceptualisations of what it means to 'think, act, and feel like a physician'. Gaps in understanding PIF, and by extension, its support mechanisms, can predispose individuals towards disengaged or unprofessional conduct and institutions towards short-sighted or reactionary responses to systemic issues. METHODS: A Systematic Evidence-Based Approach-guided systematic scoping review of PIF theories was conducted related to medical students, trainees and practising doctors, published between 1 January 2000 and 31 December 2021 in PubMed, Embase, ERIC and Scopus databases. RESULTS: A total of 2441 abstracts were reviewed, 607 full-text articles evaluated and 204 articles included. The domains identified were understanding PIF through the lens of pivotal theories and characterising PIF by delineating the underlying factors that influence it and processes that define it. CONCLUSIONS: Based on regnant theories and frameworks related to self-concepts of identity and personhood, the relationships between key PIF influences, processes and outcomes were examined. A theory-backed integrated conceptual model was proposed to delineate the interconnected relationships among these, aiming to untangle some of the complexities inherent to PIF, to shed light on existing practices and to identify shortcomings in our understanding so as to develop mechanisms in support of its multifaceted, interlinked components.
ABSTRACT
The ability to detect single photons has led to the advancement of numerous research fields1-11. Although various types of single-photon detector have been developed12, because of two main factors-that is, (1) the need for operating at cryogenic temperature13,14 and (2) the incompatibility with complementary metal-oxide-semiconductor (CMOS) fabrication processes15,16-so far, to our knowledge, only Si-based single-photon avalanche diode (SPAD)17,18 has gained mainstream success and has been used in consumer electronics. With the growing demand to shift the operation wavelength from near-infrared to short-wavelength infrared (SWIR) for better safety and performance19-21, an alternative solution is required because Si has negligible optical absorption for wavelengths beyond 1 µm. Here we report a CMOS-compatible, high-performing germanium-silicon SPAD operated at room temperature, featuring a noise-equivalent power improvement over the previous Ge-based SPADs22-28 by 2-3.5 orders of magnitude. Key parameters such as dark count rate, single-photon detection probability at 1,310 nm, timing jitter, after-pulsing characteristic time and after-pulsing probability are, respectively, measured as 19 kHz µm-2, 12%, 188 ps, ~90 ns and <1%, with a low breakdown voltage of 10.26 V and a small excess bias of 0.75 V. Three-dimensional point-cloud images are captured with direct time-of-flight technique as proof of concept. This work paves the way towards using single-photon-sensitive SWIR sensors, imagers and photonic integrated circuits in everyday life.
ABSTRACT
The deformation and fracture characteristics of rocks under freeze-thaw cycles were investigated by using uniaxial compression tests with acoustic emission (AE) monitoring. The results showed that the sandstone peak stress and elastic modulus decreased with an increasing number of freeze-thaw cycles, and the strain increased significantly. The rates of increase in the total energy and elastic energy decreased with an increasing number of freeze-thaw cycles. The freeze-thaw damage factor De was directly proportional to the number of freeze-thaw cycles. The total damage factor D was inversely proportional to the freeze-thaw cycles when the freeze-thaw-induced damage and load-induced damage were coupled. By analyzing the AE energy rate, event rate, amplitude, and frequency of the sandstone during damage, it was found that the amplitude varies irregularly with the freeze-thaw cycles and that the AE energy and event rates can better show the development of internal cracks in the sandstone. The peak frequency was the most sensitive and could be used as an index to predict when the sandstone ultimately failed. The increase in the number of freeze-thaw cycles encouraged the development of internal cracks in the sandstone. The crack characteristics change from mixed tensile-shear fractures before they undergo freeze-thaw cycles to tensile fracturing after a high number of freeze-thaw cycles. These research results provide a valuable reference for understanding the mechanisms of rock damage caused by freeze-thaw cycles as well as for making predictions about the safety of engineering structures in cold climates.