On the Elastic Stability of Folded Rings in Circular and Straight States

Single-loop elastic rings can be folded into multi-loop equilibrium configurations. In this paper, the stability of several such multi-loop states which are either circular or straight are investigated analytically and illustrated by experimental demonstrations. The analysis ascertains stability by exploring variations of the elastic energy of the rings for admissible deformations in the vicinity of the equilibrium state. The approach employed is the conventional stability analysis for elastic conservative systems which differs from most of the analyses that have been published on this class of problems, as will be illustrated by reproducing and elaborating on several problems in the literature. In addition to providing solutions to two basic problems, the paper analyses and demonstrates the stability of six-sided rings that fold into straight configurations

Puentes y barreras en la formación en interpretación en los servicios públicos: la docencia a intérpretes con experiencia no profesional

This paper reports on an action-research study with a dual purpose: (1) to design a PSI training programme adapted to the needs of the City of Québec’s public healthcare institutions, and (2) to assess its contribution to the development of trainees’ PSI competences. The course was designed adapting ÉSIT’s special regime methodology to PSI training, and delivered to a group of non-professional interpreters (N=23). The evaluation was undertaken qualitatively, through two focus groups (n=11). The data collected was submitted to content analysis and contrasted with the trainer’s action-research report. Findings reveal (1) that the special regime methodology can be applied to PSI training programmes, if combined with pedagogical approaches adjusting it to the group’s needs, and (2) that trainees’ preconceptions about PSI add up to the list of challenges of training non-professional longserving interpreters. Our concluding remarks present several recommendations on how to overcome the detected difficulties.Este artículo da cuenta de un estudio de investigación-acción con doble objetivo: (1) diseñar un programa de formación en ISP adaptado a las necesidades de las instituciones sanitariaspúblicas de la ciudad de Quebec y (2) evaluar su contribución al desarrollo de las competencias necesarias para la ISP. El curso, que adapta la metodología del régimen especial de la ÉSIT a la formación en ISP, se impartió a un grupo de intérpretes no profesionales (N=23) y se evaluócualitativamente mediante dos grupos focales (n=11). Los datos recopilados se sometieron a un análisis de contenido y se contrastaron con el informe de investigación-acción de la formadora. Los resultados revelan que (1) la metodología de régimen especial puede aplicarse a la formación en ISP, si se combina con enfoques pedagógicos que la ajusten a las necesidades del grupo, y (2) las ideas preconcebidas sobre la ISP se suman a la lista de retos que supone instruir a intérpretes con experiencia no profesional. A modo de conclusión, presentamos una serie de sugerencias para superar las dificultades detectadas

Multiple equilibrium states of a curved-sided hexagram:Part I-Stability of states

The stability of the multiple equilibrium states of a hexagram ring with six curved sides is investigated. Each of the six segments is a rod having the same length and uniform natural curvature. These rods are bent uniformly in the plane of the hexagram into equal arcs of 120deg or 240deg and joined at a cusp where their ends meet to form a 1-loop planar ring. The 1-loop rings formed from 120deg or 240deg arcs are inversions of one another and they, in turn, can be folded into a 3-loop straight line configuration or a 3-loop ring with each loop in an "8" shape. Each of these four equilibrium states has a uniform bending moment. Two additional intriguing planar shapes, 6-circle hexagrams, with equilibrium states that are also uniform bending, are identified and analyzed for stability. Stability is lost when the natural curvature falls outside the upper and lower limits in the form of a bifurcation mode involving coupled out-of-plane deflection and torsion of the rod segments. Conditions for stability, or lack thereof, depend on the geometry of the rod cross-section as well as its natural curvature. Rods with circular and rectangular cross-sections will be analyzed using a specialized form of Kirchhoff rod theory, and properties will be detailed such that all four of the states of interest are mutually stable. Experimental demonstrations of the various states and their stability are presented. Part II presents numerical simulations of transitions between states using both rod theory and a three-dimensional finite element formulation, includes confirmation of the stability limits established in Part I, and presents additional experimental demonstrations and verifications

Multiple equilibrium states of a curved-sided hexagram: Part II-Transitions between states

Curved-sided hexagrams with multiple equilibrium states have great potential in engineering applications such as foldable architectures, deployable aerospace structures, and shape-morphing soft robots. In Part I, the classical stability criterion based on energy variation was used to study the elastic stability of the curved-sided hexagram and identify the natural curvature range for stability of each state for circular and rectangular rod cross-sections. Here, we combine a multi-segment Kirchhoff rod model, finite element simulations, and experiments to investigate the transitions between four basic equilibrium states of the curved-sided hexagram. The four equilibrium states, namely the star hexagram, the daisy hexagram, the 3-loop line, and the 3-loop "8", carry uniform bending moments in their initial states, and the magnitudes of these moments depend on the natural curvatures and their initial curvatures. Transitions between these equilibrium states are triggered by applying bending loads at their corners or edges. It is found that transitions between the stable equilibrium states of the curved-sided hexagram are influenced by both the natural curvature and the loading position. Within a specific natural curvature range, the star hexagram, the daisy hexagram, and the 3-loop "8" can transform among one another by bending at different positions. Based on these findings, we identify the natural curvature range and loading conditions to achieve transition among these three equilibrium states plus a folded 3-loop line state for one specific ring having a rectangular cross-section. The results obtained in this part also validate the elastic stability range of the four equilibrium states of the curved-sided hexagram in Part I. We envision that the present work could provide a new perspective for the design of multi-functional deployable and foldable structures

Using patient companions as interpreters in the Emergency Department: an interdisciplinary quantitative and qualitative assessment

Objectives To explore the perceived and actual quality of communication and the conversational mechanisms through which misunderstandings arise in linguistically diverse Emergency Department consultations. Methods A mixed method approach was used, based on audio-records of consultations which rely on patient companions for linguistic support, and ethnographic contextual data. Interpreting errors and their potential impact on the clinical reasoning process and doctor-patient relationships were quantitatively assessed. Complementary qualitative ethnographic research provided a richer understanding of the context. The study involved interdisciplinary collaboration with specialists in applied linguistics, medicine, and psychology. Results Accurate interpretation occurred in as few as 19% of interpreter speech turns. Answering for the patient and omitting information were the most frequent errors. The nature and severity of the impact of the errors varied. Answering for the patient had the greatest clinical impact. The omission of messages from the doctor to the patient negatively affected doctor-patient relationships. Conclusion Gaps were observed between the perceived and the actual quality of communication, although patient companions often provided useful information. Practice implications In addition to raising awareness among doctors on the potential risks of using AHIs, EDs should adjust their management to increase the utilization of onsite and remote PIs.status: accepte