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  1. Abstract A discrete degree of freedom can be engineered to match the Hamiltonian of particles moving in a real-space lattice potential. Such synthetic dimensions are powerful tools for quantum simulation because of the control they offer and the ability to create configurations difficult to access in real space. Here, in an ultracold 84 Sr atom, we demonstrate a synthetic-dimension based on Rydberg levels coupled with millimeter waves. Tunneling amplitudes between synthetic lattice sites and on-site potentials are set by the millimeter-wave amplitudes and detunings respectively. Alternating weak and strong tunneling in a one-dimensional configuration realizes the single-particle Su-Schrieffer-Heeger (SSH) Hamiltonian,more »a paradigmatic model of topological matter. Band structure is probed through optical excitation from the ground state to Rydberg levels, revealing symmetry-protected topological edge states at zero energy. Edge-state energies are robust to perturbations of tunneling-rates that preserve chiral symmetry, but can be shifted by the introduction of on-site potentials.« less
    Free, publicly-accessible full text available December 1, 2023
  2. Shellular Funicular Structures (SFSs) are single-layer, two-manifold structures with anticlastic curvature, designed in the context of graphic statics. They are considered as efficient structures applicable to many functions on different scales. Due to their complex geometry, design and fabrication of SFSs are quite challenging, limiting their application in large scales. Furthermore, designing these structures for a predefined boundary condition, control, and manipulation of their geometry are not easy tasks. Moreover, fabricating these geometries is mostly possible using additive manufacturing techniques, requiring a lot of support in the printing process. Cellular funicular structures (CFSs) as strut-based spatial structures can be easilymore »designed and manipulated in the context of graphic statics. This paper introduces a computational algorithm for translating a Cellular Funicular Structure (CFS) to a Shellular Funicular Structure (SFS). Furthermore, it explains a fabrication method to build the structure out of a flat sheet of material using the origami/ kirigami technique as an ideal choice because of its accessibility, processibility, low cost, and applicability to large scales. The paper concludes by displaying a design and fabricated structure using this technique.« less
    Free, publicly-accessible full text available September 30, 2022
  3. Space frames are widely used in spatial constructions as they are lightweight, rigid, and efficient. However, when it comes to the complex and irregular spaces frames, they can be difficult to fabricate because of the uniqueness of the nodes and bars. This paper presents a novel timber space frame system that can be easily manufactured using 3-axis CNC machines, and therefore increase the ease of the design and construction of complex space frames. The form-finding of the space frame is achieved with the help of polyhedral graphic statics (PGS), and resulted form has inherent planarity which can be harnessed inmore »the materialization of the structure. Inspired by the traditional wood tectonics kerf bending and zippers are applied when devising the connection details. This system's design approach and computational process are described, and a test fabrication of a single node is made via 3-axis CNC milling and both physically and numerically tested. The structural performance shows its potential for applications in large-scale spatial structures.« less
    Free, publicly-accessible full text available September 30, 2022
  4. Free, publicly-accessible full text available August 19, 2022
  5. Free, publicly-accessible full text available September 1, 2022
  6. Introduction Twitter represents a mainstream news source for the American public, offering a valuable vehicle for learning how citizens make sense of pandemic health threats like Covid-19. Masking as a risk mitigation measure became controversial in the US. The social amplifica- tion risk framework offers insight into how a risk event interacts with psychological, social, institutional, and cultural communication processes to shape Covid-19 risk perception. Methods Qualitative content analysis was conducted on 7,024 mask tweets reflecting 6,286 users between January 24 and July 7, 2020, to identify how citizens expressed Covid-19 risk per- ception over time. Descriptive statistics were computedmore »for (a) proportion of tweets using hyperlinks, (b) mentions, (c) hashtags, (d) questions, and (e) location. Results Six themes emerged regarding how mask tweets amplified and attenuated Covid-19 risk: (a) severity perceptions (18.0%) steadily increased across 5 months; (b) mask effectiveness debates (10.7%) persisted; (c) who is at risk (26.4%) peaked in April and May 2020; (d) mask guidelines (15.6%) peaked April 3, 2020, with federal guidelines; (e) political legitimiz- ing of Covid-19 risk (18.3%) steadily increased; and (f) mask behavior of others (31.6%) composed the largest discussion category and increased over time. Of tweets, 45% con- tained a hyperlink, 40% contained mentions, 33% contained hashtags, and 16.5% were expressed as a question. Conclusions Users ascribed many meanings to mask wearing in the social media information environ- ment revealing that COVID-19 risk was expressed in a more expanded range than objective risk. The simultaneous amplification and attenuation of COVID-19 risk perception on social media complicates public health messaging about mask wearing.« less
    Free, publicly-accessible full text available September 23, 2022
  7. The recent development of three-dimensional graphic statics using polyhedral reciprocal diagrams (PGS) has greatly increased the ease of designing complex yet efficient spatial funicular structural forms, where the inherent planarity of the polyhedral geometries can be harnessed for efficient construction processes. Our previous research has shown the feasibility of leveraging this planarity in materializing a 10m-span, double-layer glass bridge made of 1cm glass sheets. This paper presents a smaller bridge prototype with a span of 2.5m to address the larger bridge’s challenges regarding form-finding, detail developments, fabrication constraints, and assembly logic. The compression-only prototype is designed for prefabrication as amore »modular system using PolyFrame for Rhinoceros. Thirteen polyhedral cells of the funicular bridge are materialized in the form of hollow glass units (HGUs) and can be prefabricated and assembled on-site. Each HGU consists of two deck plates and multiple side plates held together using 3M™ Very High Bond (VHB) tape. A male-female glass connection mechanism is developed at the sides of HGUs to interlock each unit with its adjacent cells to prevent sliding. A transparent interface material is placed between the male and female connecting parts to avoid local stress concentration. This novel construction method significantly simplifies the bridge’s assembly on a large scale. The design and construction of this small-scale prototype set the foundation for the future development of the full-scale structure.« less
    Free, publicly-accessible full text available August 1, 2022