Mechanical systems can display topological characteristics similar to that of topological insulators. Here we report a large class of topological mechanical systems related to the BDI symmetry class. These are self-assembled chains of rigid bodies with an inversion centre and no reflection planes. The particle-hole symmetry characteristic to the BDI symmetry class stems from the distinct behaviour of the translational and rotational degrees of freedom under inversion. This and other generic properties led us to the remarkable conclusion that, by adjusting the gyration radius of the bodies, one can always simultaneously open a gap in the phonon spectrum, lock-in all the characteristic symmetries and generate a non-trivial topological invariant. The particle-hole symmetry occurs around a finite frequency, and hence we can witness a dynamical topological Majorana edge mode. Contrasting a floppy mode occurring at zero frequency, a dynamical edge mode can absorb and store mechanical energy, potentially opening new applications of topological mechanics.
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Background & Objective: The VSTEP Examination Suite, a collection of evidence-based standardized assessments for persons post-stroke, was evaluated as an educational tool by physical therapy students and faculty.
Methods: Six students from a Doctor of Physical Therapy program in the US and six faculty who teach standardized assessments in different physical therapy programs from the US and Israel interacted with the system using a talk-aloud procedure. Transcripts were coded deductively with a priori categories of usability, usefulness and labeled with negative or positive valences. A second round of inductive coding yielded emergent themes based on theories of technology adoption, clinical reasoning and education.
Results: Frequencies and valences of the deductive themes of usefulness and usability were tested for differences between faculty and students using a Wilcoxon Sign Rank test. Faculty comments with positive valence for usefulness were lowest for the 6MWT (83%) and for the students on the 4SQT (92%). Usefulness scores were not significantly different between faculty and students. For usability, faculty and students had the lowest positive valence scores for the 10MWT (50%). Students had a statistically significant higher number of negative usability comments compared to faculty (W=0, p =0.017) specifically for the 5XSTS (W=0.5, p = 0.022). Themes emerged related to variable knowledge about the standardized tests, value as a teaching and learning tool, technology being consistent with clinical reasoning in addition to ensuring reliability, expert-to-novice clinical reasoning (students) and usability.
Conclusions: The VSTEP was found to be useful by both faculty and students, and usability testing revealed opportunities for technology refinement.
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