195 research outputs found
Site symmetry and crystal symmetry: a spherical tensor analysis
The relation between the properties of a specific crystallographic site and
the properties of the full crystal is discussed by using spherical tensors. The
concept of spherical tensors is introduced and the way it transforms under the
symmetry operations of the site and from site to site is described in detail.
The law of spherical tensor coupling is given and illustrated with the example
of the electric dipole and quadrupole transitions in x-ray absorption
spectroscopy. The main application of the formalism is the reduction of
computation time in the calculation of the properties of crystals by band
structure methods. The general approach is illustrated by the examples of
substitutional chromium in spinel and substitutional vanadium in garnet.Comment: 27 pages, 3 figure
Experimental evidence of thermal fluctuations on the X-ray absorption near-edge structure at the aluminum K-edge
After a review of temperature-dependent experimental x-ray absorption
near-edge structure (XANES) and related theoretical developments, we present
the Al K-edge XANES spectra of corundum and beryl for temperature ranging from
300K to 930K. These experimental results provide a first evidence of the role
of thermal fluctuation in XANES at the Al K-edge especially in the pre-edge
region. The study is carried out by polarized XANES measurements of single
crystals. For any orientation of the sample with respect to the x-ray beam, the
pre-edge peak grows and shifts to lower energy with temperature. In addition
temperature induces modifications in the position and intensities of the main
XANES features. First-principles DFT calculations are performed for both
compounds. They show that the pre-edge peak originates from forbidden 1s to 3s
transitions induced by vibrations. Three existing theoretical models are used
to take vibrations into account in the absorption cross section calculations:
i) an average of the XANES spectra over the thermal displacements of the
absorbing atom around its equilibrium position, ii) a method based on the crude
Born-Oppenheimer approximation where only the initial state is averaged over
thermal displacements, iii) a convolution of the spectra obtained for the atoms
at the equilibrium positions with an approximate phonon spectral function. The
theoretical spectra so obtained permit to qualitatively understand the origin
of the spectral modifications induced by temperature. However the correct
treatment of thermal fluctuation in XANES spectroscopy requires more
sophisticated theoretical tools
Virtual patients design and its effect on clinical reasoning and student experience : a protocol for a randomised factorial multi-centre study
Background
Virtual Patients (VPs) are web-based representations of realistic clinical cases. They are proposed as being an optimal method for teaching clinical reasoning skills. International standards exist which define precisely what constitutes a VP. There are multiple design possibilities for VPs, however there is little formal evidence to support individual design features. The purpose of this trial is to explore the effect of two different potentially important design features on clinical reasoning skills and the student experience. These are the branching case pathways (present or absent) and structured clinical reasoning feedback (present or absent).
Methods/Design
This is a multi-centre randomised 2x2 factorial design study evaluating two independent variables of VP design, branching (present or absent), and structured clinical reasoning feedback (present or absent).The study will be carried out in medical student volunteers in one year group from three university medical schools in the United Kingdom, Warwick, Keele and Birmingham. There are four core musculoskeletal topics. Each case can be designed in four different ways, equating to 16 VPs required for the research. Students will be randomised to four groups, completing the four VP topics in the same order, but with each group exposed to a different VP design sequentially. All students will be exposed to the four designs. Primary outcomes are performance for each case design in a standardized fifteen item clinical reasoning assessment, integrated into each VP, which is identical for each topic. Additionally a 15-item self-reported evaluation is completed for each VP, based on a widely used EViP tool. Student patterns of use of the VPs will be recorded.
In one centre, formative clinical and examination performance will be recorded, along with a self reported pre and post-intervention reasoning score, the DTI. Our power calculations indicate a sample size of 112 is required for both primary outcomes
Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H
A model of the collisional kinetics of energetic hydrogen atoms, molecules,
and ions in pure H discharges is used to predict H emission
profiles and spatial distributions of emission from the cathode regions of
low-pressure, weakly-ionized discharges for comparison with a wide variety of
experiments. Positive and negative ion energy distributions are also predicted.
The model developed for spatially uniform electric fields and current densities
less than A/m is extended to non-uniform electric fields, current
densities of A/m, and electric field to gas density ratios MTd at 0.002 to 5 Torr pressure. (1 Td = V m and 1 Torr =
133 Pa) The observed far-wing Doppler broadening and spatial distribution of
the H emission is consistent with reactions among H, H,
H, and H ions, fast H atoms, and fast H molecules, and with
reflection, excitation, and attachment to fast H atoms at surfaces. The
H excitation and H formation occur principally by collisions of
fast H, fast H, and H with H. Simplifications include using a
one-dimensional geometry, a multi-beam transport model, and the average
cathode-fall electric field. The H emission is linear with current
density over eight orders of magnitude. The calculated ion energy distributions
agree satisfactorily with experiment for H and H, but are only in
qualitative agreement for H and H. The experiments successfully modeled
range from short-gap, parallel-plane glow discharges to beam-like,
electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201
Proposed Standards for Medical Education Submissions to the Journal of General Internal Medicine
To help authors design rigorous studies and prepare clear and informative manuscripts, improve the transparency of editorial decisions, and raise the bar on educational scholarship, the Deputy Editors of the Journal of General Internal Medicine articulate standards for medical education submissions to the Journal. General standards include: (1) quality questions, (2) quality methods to match the questions, (3) insightful interpretation of findings, (4) transparent, unbiased reporting, and (5) attention to human subjectsā protection and ethical research conduct. Additional standards for specific study types are described. We hope these proposed standards will generate discussion that will foster their continued evolution
Workplace learning from a socio-cultural perspective: creating developmental space during the general practice clerkship
Workplace learning in undergraduate medical education has predominantly been studied from a cognitive perspective, despite its complex contextual characteristics, which influence medical studentsā learning experiences in such a way that explanation in terms of knowledge, skills, attitudes and single determinants of instructiveness is unlikely to suffice. There is also a paucity of research which, from a perspective other than the cognitive or descriptive one, investigates student learning in general practice settings, which are often characterised as powerful learning environments. In this study we took a socio-cultural perspective to clarify how students learn during a general practice clerkship and to construct a conceptual framework that captures this type of learning. Our analysis of group interviews with 44 fifth-year undergraduate medical students about their learning experiences in general practice showed that students needed developmental space to be able to learn and develop their professional identity. This space results from the intertwinement of workplace context, personal and professional interactions and emotions such as feeling respected and self-confident. These forces framed studentsā participation in patient consultations, conversations with supervisors about consultations and studentsā observation of supervisors, thereby determining the opportunities afforded to students to mind their learning. These findings resonate with other conceptual frameworks and learning theories. In order to refine our interpretation, we recommend that further research from a socio-cultural perspective should also explore other aspects of workplace learning in medical education
Benefits of knowledge-based interprofessional communication skills training in medical undergraduate education
OBJECTIVES: Good interprofessional communication is fundamental to effective teamworking in medicine. Finalmed is a private course that teaches the principles and methods of clinical presenting as an iterative technique of reasoning though clinical data. We have tested the efficacy of this technique using a questionnaire-based study. DESIGN: An anonymized 10-point Likert scale questionnaire was designed. SETTING: Questionnaires were distributed at five UK courses and two UAE courses. PARTICIPANTS: Questionnaires were given to all students attending these courses. MAIN OUTCOME MEASURES: The questionnaire included pre- and post-course questions addressing self-reported confidence in clinical presenting (CCP) and effectiveness in clinical presenting (ECP). We also asked whether attendees felt that clinical presenting should be integrated formally into medical school curricula. RESULTS: A total of 331/395 questionnaires were returned. Median improvement in CCP was 50% (P < 0.0001) and in ECP was 40% (P < 0.0001), irrespective of country of study, graduate entry status and whether the student felt that they had been exposed to these techniques previously. Students recorded a strong opinion in favour of integrating the content and style of the Finalmed course into their medical school curriculum, with 286 students (86%) recording a score of ā„8. CONCLUSION: Our study suggests that after a two- or three-day dedicated course, both self-reported confidence and effectiveness in clinical presenting significantly improve. Furthermore, students in the UK and the UAE returned a desire for integration into medical school curricula of IPC through the teaching of clinical presenting
Report on G4āMed, a Geant4 benchmarking system for medical physics applications developed by the Geant4 Medical Simulation Benchmarking Group
Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, microā and nanoā dosimetry, imaging, radiation protection and nuclear medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing. To respond to these needs, we developed G4āMed, a benchmarking and regression testing system of Geant4 for medical physics, that currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the preābuilt, Geant4 physics lists are tested. The tests included in G4āMed are executed on the CERN computing infrastructure via the use of the geantāval web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes. This paper describes the tests included in G4āMed and shows the results derived from the benchmarking of Geant4 10.5 against reference data. The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.D. Bolst acknowledges the support of the Australian Government Research Training Program Scholarship. M. A. Cort Ģes-Giraldo, A. Perales, and J. M. Quesada acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness under grant FPA2016-77689-C2-1-R. B. Faddegon and J. Ramos-M Ģendez acknowledge partial financial support from the NIH grant U24CA215123. D. Bolst, S. Guatelli, D. Sakata, S.Incerti, and I. Kyriakou acknowledge financial support from the Australian Research Council, ARC DP170100967. S. Incerti acknowledges the financial support of CNRS through the IN2P3/MOVI Master Project and through the France-Greece PICS 8235 funding scheme. I. Kyriakou acknowledges additional financial support from the European Space Agency (Contract No. 4000126645/19/NL/BW). E. C. Simpson acknowledges financial support from the Australian Research Council under grant DP170102423. I. Sechopoulos and C. Fedon acknowledge financial support from the Susan G Komen Foundation for the Cure grant IIR13262248. S. Guatelli and D. Bolst acknowlege the use of computing resources of the Aus-tralian National Computing Infrastructure (NCI), through the NCMAS 2020 grant scheme
Valued experiences of graduate students in their role as educators in undergraduate training in Ugandan medical schools
Online patient simulation training to improve clinical reasoning: a feasibility randomised controlled trial
Background Online patient simulations (OPS) are a novel method for teaching clinical reasoning skills to students and could contribute to reducing diagnostic errors. However, little is known about how best to implement and evaluate OPS in medical curricula. The aim of this study was to assess the feasibility, acceptability and potential effects of eCREST ā the electronic Clinical Reasoning Educational Simulation Tool. Methods A feasibility randomised controlled trial was conducted with final year undergraduate students from three UK medical schools in academic year 2016/2017 (cohort one) and 2017/2018 (cohort two). Student volunteers were recruited in cohort one via email and on teaching days, and in cohort two eCREST was also integrated into a relevant module in the curriculum. The intervention group received three patient cases and the control group received teaching as usual; allocation ratio was 1:1. Researchers were blind to allocation. Clinical reasoning skills were measured using a survey after 1 week and a patient case after 1 month. Results Across schools, 264 students participated (18.2% of all eligible). Cohort two had greater uptake (183/833, 22%) than cohort one (81/621, 13%). After 1 week, 99/137 (72%) of the intervention and 86/127 (68%) of the control group remained in the study. eCREST improved studentsā ability to gather essential information from patients over controls (ORā=ā1.4; 95% CI 1.1ā1.7, nā=ā148). Of the intervention group, most (80/98, 82%) agreed eCREST helped them to learn clinical reasoning skills. Conclusions eCREST was highly acceptable and improved data gathering skills that could reduce diagnostic errors. Uptake was low but improved when integrated into course delivery. A summative trial is needed to estimate effectiveness
- ā¦