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Radar sounding is a powerful geophysical approach for characterizing the subsurface conditions of terrestrial and planetary ice masses at local to global scales. As a result, a wide array of orbital, airborne, ground-based, and in situ instruments, platforms and data analysis approaches for radioglaciology have been developed, applied or proposed. Terrestrially, airborne radar sounding has been used in glaciology to observe ice thickness, basal topography and englacial layers for five decades. More recently, radar sounding data have also been exploited to estimate the extent and configuration of subglacial water, the geometry of subglacial bedforms and the subglacial and englacial thermal states of ice sheets. Planetary radar sounders have observed, or are planned to observe, the subsurfaces and near-surfaces of Mars, Earth's Moon, comets and the icy moons of Jupiter. In this review paper, and the thematic issue of the Annals of Glaciology on ‘Five decades of radioglaciology’ to which it belongs, we present recent advances in the fields of radar systems, missions, signal processing, data analysis, modeling and scientific interpretation. Our review presents progress in these fields since the last radio-glaciological Annals of Glaciology issue of 2014, the context of their history and future prospects.
Competence committees play a key role in a competency-based system of assessment. These committees are tasked with reviewing and synthesizing clinical performance data to make judgments regarding residents’ competence. Canadian emergency medicine (EM) postgraduate training programs recently implemented competence committees; however, a paucity of literature guides their work.
The objective of this study was to develop consensus-based recommendations to optimize the function and decisions of competence committees in Canadian EM training programs.
Semi-structured interviews of EM competence committee chairs were conducted and analyzed. The interview guide was informed by a literature review of competence committee structure, processes, and best practices. Inductive thematic analysis of interview transcripts was conducted to identify emerging themes. Preliminary recommendations, based on themes, were drafted and presented at the 2019 CAEP Academic Symposium on Education. Through a live presentation and survey poll, symposium attendees representing the national EM community participated in a facilitated discussion of the recommendations. The authors incorporated this feedback and identified consensus among symposium attendees on a final set of nine high-yield recommendations.
The Canadian EM community used a structured process to develop nine best practice recommendations for competence committees addressing: committee membership, meeting processes, decision outcomes, use of high-quality performance data, and ongoing quality improvement. These recommendations can inform the structure and processes of competence committees in Canadian EM training programs.
IQ as a measure of intelligence is at the same time a success and a failure: a success because of the predictive value of IQ, and a failure because we do not know precisely what it is measuring. Intelligence has been defined in many ways. To discuss the definitional issue, we rely on Aristotle and his four ways to define something: explaining what it looks like, what it consists of, where it comes from, and what it is for. In this chapter we present an alternative view on how the measurement of intelligence has evolved and how it relates to different views on what intelligence is. The first initiatives to measure intelligence were inspired by physics and a strictly quantitative approach. These initiatives were based on the notion of general intelligence as mental energy, and led to tests to measure intelligence such as reaction times and perceptual discrimination (i.e., what intelligence looks like). IQ as a quantification of intelligence is from a later date and is based on a quite different type of test, inspired by an interest in what intelligence is for, as expressed in the work of some of the most famous intelligence test developers (e.g., Binet, Terman, Wechsler). The type of content of these tests is preserved in most intelligence tests today, mainly because of the predictive success of IQ tests. There now is also agreement that intelligence is not unitary but multidimensional. Robert Sternberg’s major endeavor to unravel processes has shown that there is no clear-cut answer to the question of what intelligence consists of in terms of cognitive processes or how processes can be measured. Other endeavors have resulted in measurement of genetic and environmental influences, in a revival of reaction time and discrimination measures, and in hypotheses about biological mechanics, such as mitochondrial efficiency. We conclude that intelligence is still a vague concept without much hope that it will be clarified soon, even though its measurement through a variety of cognitive tasks seems to work well from a predictive point of view.
The detection of fireballs streaks in astronomical imagery can be carried out by a variety of methods. The Desert Fireball Network uses a network of cameras to track and triangulate incoming fireballs to recover meteorites with orbits and to build a fireball orbital dataset. Fireball detection is done on-board camera, but due to the design constraints imposed by remote deployment, the cameras are limited in processing power and time. We describe the processing software used for fireball detection under these constrained circumstances. Two different approaches were compared: (1) A single-layer neural network with 10 hidden units that were trained using manually selected fireballs and (2) a more traditional computational approach based on cascading steps of increasing complexity, whereby computationally simple filters are used to discard uninteresting portions of the images, allowing for more computationally expensive analysis of the remainder. Both approaches allowed a full night’s worth of data (over a thousand 36-megapixel images) to be processed each day using a low-power single-board computer. We distinguish between large (likely meteorite-dropping) fireballs and smaller fainter ones (typical ‘shooting stars’). Traditional processing and neural network algorithms both performed well on large fireballs within an approximately 30 000-image dataset, with a true positive detection rate of 96% and 100%, respectively, but the neural network was significantly more successful at smaller fireballs, with rates of 67% and 82%, respectively. However, this improved success came at a cost of significantly more false positives for the neural network results, and additionally the neural network does not produce precise fireball coordinates within an image (as it classifies). Simple consideration of the network geometry indicates that overall detection rate for triangulated large fireballs is calculated to be better than 99.7% and 99.9%, by ensuring that there are multiple double-station opportunities to detect any one fireball. As such, both algorithms are considered sufficient for meteor-dropping fireball event detection, with some consideration of the acceptable number of false positives compared to sensitivity.
To examine the relationship between unit-wide Clostridium difficile infection (CDI) susceptibility and inpatient mobility and to create contagion centrality as a new predictive measure of CDI.
Retrospective cohort study.
A mobility network was constructed using 2 years of patient electronic health record data for a 739-bed hospital (n = 72,636 admissions). Network centrality measures were calculated for each hospital unit (node) providing clinical context for each in terms of patient transfers between units (ie, edges). Daily unit-wide CDI susceptibility scores were calculated using logistic regression and were compared to network centrality measures to determine the relationship between unit CDI susceptibility and patient mobility.
Closeness centrality was a statistically significant measure associated with unit susceptibility (P < .05), highlighting the importance of incoming patient mobility in CDI prevention at the unit level. Contagion centrality (CC) was calculated using inpatient transfer rates, unit-wide susceptibility of CDI, and current hospital CDI infections. The contagion centrality measure was statistically significant (P < .05) with our outcome of hospital-onset CDI cases, and it captured the additional opportunities for transmission associated with inpatient transfers. We have used this analysis to create easily interpretable clinical tools showing this relationship as well as the risk of hospital-onset CDI in real time, and these tools can be implemented in hospital EHR systems.
Quantifying and visualizing the combination of inpatient transfers, unit-wide risk, and current infections help identify hospital units at risk of developing a CDI outbreak and, thus, provide clinicians and infection prevention staff with advanced warning and specific location data to inform prevention efforts.
Pulmonary hypertension is a complex and progressive condition that is either idiopathic or heritable, or associated with one or multiple health conditions, with or without congenital or acquired cardiovascular disease. Recent developments have tremendously increased the armamentarium of diagnostic and therapeutic approaches in children and young adults with pulmonary hypertension that is still associated with a high morbidity and mortality. These modalities include non-invasive imaging, pharmacotherapy, interventional and surgical procedures, and supportive measures. The optimal, tailored diagnostic and therapeutic strategies for pulmonary hypertension in the young are rapidly evolving but still face enormous challenges: Healthcare providers need to take the patient’s age, development, disease state, and family concerns into account when initiating advanced diagnostics and treatment. Therefore, there is a need for guidance on core and advanced medical training in paediatric pulmonary hypertension. The Association for European Paediatric and Congenital Cardiology working group “pulmonary hypertension, heart failure and transplantation” has produced this document as an expert consensus statement; however, all recommendations must be considered and applied in the context of the local and national infrastructure and legal regulations.
This paper presents a novel approach for the determination of True-Speed-Over-Ground for trains. Speed determination is accomplished by correlating the received signals of two side-looking radar sensors. The theoretically achievable precision is derived. Test measurements are done in two different scenarios to give a proof of concept. Thereafter a series of field measurements is performed to rate the practical suitability of the approach. The results of the measurements are thoroughly evaluated. The test and field measurements are carried out using a 24 GHz frequency modulated continuous wave radar.
In this note, we provide an explicit formula for computing the quasiconvex envelope of any real-valued function W; SL(2) → ℝ with W(RF) = W(FR) = W(F) for all F ∈ SL(2) and all R ∈ SO(2), where SL(2) and SO(2) denote the special linear group and the special orthogonal group, respectively. In order to obtain our result, we combine earlier work by Dacorogna and Koshigoe on the relaxation of certain conformal planar energy functions with a recent result on the equivalence between polyconvexity and rank-one convexity for objective and isotropic energies in planar incompressible nonlinear elasticity.
Transcatheter stent implantation has been employed to treat re-coarctation of the aorta in adolescents and young adults. The aim of this work is to use computational fluid dynamics to characterise haemodynamics associated with re-coarctation involving an aneurysmal ductal ampulla and aortic isthmus narrowing, which created minimal pressure drop, and to incorporate computational fluid dynamics’s findings into decision-making concerning catheter-directed treatment.
Computational fluid dynamics permits numerically solving the Navier–Stokes equations governing pulsatile flow in the aorta, based on patient-specific data. We determined flow-velocity fields, wall shear stresses, oscillatory shear indices, and particle stream traces, which cannot be ascertained from catheterisation data or magnetic resonance imaging.
Computational fluid dynamics showed that, as flow entered the isthmus, it separated from the aortic wall, and created vortices leading to re-circulating low-velocity flow that induced low and multidirectional wall shear stress, which could sustain platelet-mediated thrombus formation in the ampulla. In contrast, as flow exited the isthmus, it created a jet leading to high-velocity flow that induced high and unidirectional wall shear stress, which could eventually undermine the wall of the descending aorta.
We used computational fluid dynamics to study re-coarctation involving an aneurysmal ductal ampulla and aortic isthmus narrowing. Despite minimal pressure drop, computational fluid dynamics identified flow patterns that would place the patient at risk for: thromboembolic events, rupture of the ampulla, and impaired descending aortic wall integrity. Thus, catheter-directed stenting was undertaken and proved successful. Computational fluid dynamics yielded important information, not only about the case presented, but about the complementary role it can serve in the management of patients with complex aortic arch obstruction.
Workforce shortages in psychiatry are common worldwide. The international literature provides insights into factors influencing decisions to train in psychiatry but is predominately survey based. This national cohort study aimed to identify the characteristics of doctors who were most likely to apply to psychiatry training programmes. The sample comprised doctors who entered UK medical schools in 2007/8 and who made first-time specialty training applications in 2015. The association between application to psychiatry and doctors' sociodemographic and educational characteristics was examined using multivariable logistic regression.
Those most likely to apply were White, privately educated older doctors with below average performance at medical school.
To reduce workforce shortages, psychiatry must make itself more attractive to all doctors, especially those from underrepresented groups such as state-educated Black and minority ethnic individuals. Otherwise, national policies to widen participation in the study of medicine by such groups may exacerbate the current recruitment crisis.
We describe the new species ognitite, NiBiTe, and a Co-rich variety of maucherite, hitherto unreported; both were discovered in the Ognit ultramafic complex of Neoproterozoic age in Eastern Sayans, Russia. The mean composition of ognitite (n = 7) is: Ni 17.05, Fe 0.07, Cu 0.14, Pd 0.14, Te 32.53, Bi 49.64, total 99.57 wt.%, corresponding to: (Ni1.11Cu0.008Fe0.005Pd0.005)Σ1.13Bi0.90Te0.97 (Σ atoms = 3 apfu). Ognitite is trigonal, space group P3m1 [R1 = 0.0276 for 81 reflections with Fo > 4σ(Fo)]. The unit-cell parameters derived from the single-crystal X-ray diffraction data are: a = 3.928(1) Å, c = 5.385(1) Å and V = 71.95(4) Å3, with Z = 1. The c:a ratio is 1.37. The powder X-ray diffraction data obtained on the same fragment used for the single-crystal study are: a = 3.9332(4) Å, c = 5.3920(6) Å and V = 72.24(1) Å3. Ognitite exhibits the brucite-type structure with edge-sharing NiTe3Bi3 octahedra forming sheets parallel to (0001). It is related to melonite, but is distinct compositionally by the extreme Bi-enrichment (melonite and its synthetic analogue contain <0.4 Bi apfu), and structurally as Bi and Te are ordered at two distinct sites, leading to the loss of the centre of symmetry in ognitite.
At more than 9 wt.% Co, or ~2 apfu Co, the core of Co-rich maucherite [(Ni,Co)11As8] in a zoned crystal, which is surrounded by Co-depleted orcelite, far surpasses the norm (≤1 and up to 3.9 wt.% Co). The unit-cell parameters of the Co-rich maucherite are: a = 6.85(2) and c = 21.83(5) Å, which are based on results of synchrotron micro-Laue diffraction.
The host rock consists of serpentine, clinochlore (Mg# 95–97) and skeletal chromite. We favour the metastable crystallisation of fluid-saturated globules of a sulfide–arsenide melt to explain the anomalous compositions of ore minerals at Ognit. These anomalies seem consistent with rapid cooling in a fluid-enriched system, possibly related to late-stage degassing of the magma, as reflected in a prominent metasomatic aureole at the contact with the enclosing gneissic rocks.
Chromitite zones associated with ultramafic units of the Lysanskiy layered complex of dunite–peridotite–gabbro composition could well represent the primary source for the placers bearing platinum-group minerals (PGM) of the entire drainage of the River Sisim and its tributaries, the rivers Ko and Seyba, eastern Sayans. Alluvial gold present in the placers of River Seyba, as elsewhere in the Sisim Placer Zone, reflects mineralisation during a recent period of tectonic activity. We focus on the PGM in the Seyba suite, and in particular on the attributes of pentlandite enriched in platinum-group-elements (PGE) and the compositionally similar and recently defined ferhodsite, which were trapped in host grains of Os–Ir–Ru alloy. Both minerals formed from small volumes of fractionated Fe–Ni–Cu melt considerably enriched in the PGE. In the Seyba suite, as in several others, the amounts of PGE in ferhodsite exceeds that in pentlandite, which results in a greater proportion of vacancies than in pentlandite.