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    Programming Mechanics in Knitted Materials, Stitch by Stitch Data Repository
    (Georgia Institute of Technology, 2024-02) Singal, Krishma ; Dimitriyev, Michael S. ; Gonzalez, Sarah E. ; Cachine, Alexander P. ; Quinn, Sam ; Matsumoto, Elisabetta A.
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    Microcat, Aquadopp, and ADCP data from the 2020-2022 Labrador Sea eastern boundary mooring array as part of the Overturning in the Subpolar North Atlantic Program (OSNAP)
    (Georgia Institute of Technology, 2024-01) Pickart, Robert S.
    The Overturning of the Subpolar North Atlantic Program (OSNAP) is an effort to determine the strength of the meridional overturning circulation and associated heat and freshwater fluxes in the subpolar North Atlantic. It is a collaborative program with scientists from the U.S., U.K., Netherlands, Germany, France, Canada, and China. Together, moorings were deployed across the boundaries of the Labrador Sea, Irminger Sea, Iceland Basin, and eastern subpolar North Atlantic. The OSNAP West array consists of 11 moorings spanning from the west Greenland shelf to the base of the continental slope. The 6 shelf moorings are bottom tripods, while the five offshore moorings are tall moorings. The tripod moorings contained a weak-link extension to obtain hydrographic measurements 50 m below the surface. Velocity was measured using a combination of Aquadopps and acoustic Doppler current profilers (ADCPs), and the pressure, temperature, and salinity were measured using MicroCATs. The time period of the deployment of the array was August 2020 to August 2022. All of the data have been calibrated, processed, and quality controlled.
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    Experimental Data for "Spatial constraints and stochastic seeding subvert microbial arms race"
    (Georgia Institute of Technology, 2024-01) Copeland, Raymond ; Zhang, Christopher ; Hammer, Brian K. ; Yunker, Peter J.
    This item is the experimental data for figures 7 and 8 of the paper titled "Spatial constraints and stochastic seeding subvert microbial arms race" which was accepted at PLOS computational biology.
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    Raw data and simulation code for "Quantum-to-classical crossover in generalized spin systems – the temperature-dependent spin dynamics of FeI2"
    (Georgia Institute of Technology, 2024-01) Mourigal, Martin
    Simulating quantum spin systems at finite temperatures is an open challenge in many-body physics. This work studies the temperature-dependent spin dynamics of a pivotal compound, FeI2, to determine if universal quantum effects can be accounted for by a phenomenological renormalization of the dynamical spin structure factor S(q,ω) measured by inelastic neutron scattering. Renormalization schemes based on the quantum-to-classical correspondence principle are commonly applied at low temperatures to the harmonic oscillators describing normal modes. However, it is not clear how to extend this renormalization to arbitrarily high temperatures. Here we introduce a temperature-dependent normalization of the classical moments, whose magnitude is determined by imposing the quantum sum rule, i.e. ∫dωdqS(q,ω)=NSS(S+1) for NS dipolar magnetic moments. We show that this simple renormalization scheme significantly improves the agreement between the calculated and measured S(q,ω) for FeI2 at all temperatures. Due to the coupled dynamics of dipolar and quadrupolar moments in that material, this renormalization procedure is extended to classical theories based on SU(3) coherent states, and by extension, to any SU(N) coherent state representation of local multipolar moments.
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    Metagenomic evaluation of the performance of passive Moore swabs for sewage monitoring relative to composite sampling over time resolved deployments
    (Georgia Institute of Technology, 2024-01) Cha, Gyuhyon ; Zhu, Kevin J. ; Fisher, Jamie M. ; Flores, Camryn I. ; Brown, Joe ; Pinto, Ameet ; Hatt, Janet K. ; Konstantinos, Kostas T. ; Graham, Katherine E.
    Moore swabs have re-emerged as a versatile tool in the field of wastewater-based epidemiology during the COVID-19 pandemic and offer unique advantages for monitoring pathogens in sewer systems, especially at the neighborhood-level. However, whether Moore swabs provide comparable results to more commonly used composite samples remains to be rigorously tested including the optimal duration of Moore swab deployment. This study provides new insights into these issues by comparing the results from Moore swab samples to those of paired composite samples collected from the same sewer lines continuously over six to seventy-two hours post-deployment, during low COVID-19 prevalence periods. Our results show that Moore swabs accumulated approximately 10-fold higher PMMoV concentrations (on a basis of mL of Moore swab squeezed filtrate to mL of composite sewage) and showed comparable trends in terms of bacterial species abundance when compared to composite samples. Moore swabs also generally captured higher SARS-CoV-2 N1/N2 RNA concentrations than composite samples. Moore swabs showed comparable trends in terms of abundance dynamics of the sewage microbiome to composite samples and variable signs of saturation over time that were site and/or microbial population-specific. Based on our dual ddRT-PCR and shotgun metagenomic approach, we find that Moore swabs at our sites were optimally deployed for 6 hours at a time at two sites.
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    Data for the publication "Pressure control of magnetic order and excitations in the pyrochlore antiferromagnet MgCr2O4"
    (Georgia Institute of Technology, 2024-01) Mourigal, Martin
    MgCr2O4 is one of the best-known realizations of the pyrochlore-lattice Heisenberg antiferromagnet. The strong antiferromagnetic exchange interactions are perturbed by small further-neighbor exchanges such that this compound may in principle realize a spiral spin liquid (SSL) phase in the zero-temperature limit. However, a spin Jahn-Teller transition below TN≈13 K yields a complicated long-range magnetic order with multiple coexisting propagation vectors. We present neutron scattering and thermo-magnetic measurements of MgCr2O4 samples under applied hydrostatic pressure up to P=1.7 GPa demonstrating the existence of multiple close-lying nearly degenerate magnetic ground states. We show that the application of hydrostatic pressure increases the ordering temperature by around 0.8 K per GPa and increases the bandwidth of the magnetic excitations by around 0.5 meV per GPa. We also evidence a strong tendency for the preferential occupation of a subset of magnetic domains under pressure. In particular, we show that the k=(0,0,1) magnetic phase, which is almost negligible at ambient pressure, dramatically increases in spectral weight under pressure. This modifies the spectrum of magnetic excitations, which we interpret unambiguously as spin waves from multiple magnetic domains. Moreover, we report that the application of pressure reveals a feature in the magnetic susceptibility above the magnetostructural transition. We interpret this as the onset of a short-range ordered phase associated with k=(0,0,1), previously not observed in magnetometry measurements.
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    Raw data for article: "Moth resonant mechanics are tuned to wingbeat frequency and energetic demands"
    (Georgia Institute of Technology, 2023-12) Wold, Ethan ; Aiello, Brett ; Harris, Manon ; bin Sikandar, Usama ; Lynch, James ; Gravish, Nick ; Sponberg, Simon
    Raw data accompanying the article "Moth resonance mechanics are tuned to wingbeat frequency and energetic demands".
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    Water-limited hydrothermalism and volcanic resurfacing of Eridania Basin, Mars
    (Georgia Institute of Technology, 2023) Hughes, Emmy B. ; Wray, James J. ; Karunatillake, Suniti ; Fanson, Grace ; Harrington, Elise ; Hood, Don
    The Eridania Basin system, located in the martian southern highlands, is considered a promising site of long-lived submarine hydrothermalism. Despite its multi-basin scale and suggested longevity that should pervasively alter the regolith, anticipated compositional signatures have been unexplored at regional scales. Here we synthesize orbital datasets (derived from the Gamma Ray Spectrometer, GRS; Thermal Emission Spectrometer, TES; and Compact Reconnaissance Imaging Spectrometer for Mars, CRISM) to characterize the composition of Eridania’s landscape progressively from regional to outcrop scales. The bulk geochemistry representing decimeter depths and mineralogy of the Eridania region lack substantial evidence for a long-lived lacustrine body. Instead, regional chemical trends are consistent with minor alteration and a generally mafic composition, with a local-scale mineralogy of ~4 wt.% olivine, ~25 wt.% plagioclase, ~20 wt.% high-Ca pyroxene, ~13 wt.% low-Ca pyroxene, and less than 1 wt.% clays. Meanwhile, chloride mapping and analyses of amorphous silica phases at outcrop scale both show that any hydrothermal alteration and putative lacustrine activity was likely limited to the northernmost basin—i.e., Atlantis Chaos—and that most other amorphous silica in Eridania is consistent with low-to-minimal water/rock weathering. Our findings collectively suggest that Eridania underwent localized crustal hydrothermal alteration, perhaps akin to sinter and fumarole units on Earth, with any paleolakes either short-lived or extensively resurfaced to at least meter scale depths by later volcanism. This supports prior inferences of spatially and temporally limited fluvial processes on Mars and extensive volcanic resurfacing of basins, as in Gusev Crater.
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    Dataset for "Investigating shock and vibration exposure of a manual wheelchair during multi-drum testing"
    (Georgia Institute of Technology, 2023-09-21) Misch, Jacob ; Sprigle, Stephen
    Wheelchair users are highly susceptible to injury and immobility in the event of a wheelchair breakdown. Durability, or fatigue life, of manual wheelchair frames is currently evaluated using a standardized multi-drum test, which provides frequent impacts to the casters and rear wheels of the wheelchair. Not much is known about the underlying mechanics of the test, making it difficult to properly assess how appropriate this test is as a predictor of wheelchair frame longevity during real-world usage. This study aimed to investigate the applicability of the multi-drum test as an accelerated durability test by comparing breakdown statistics, vibrations, and shocks between the test and real-world usage. Triaxial accelerometers were used to measure the shocks and vibrations transmitted through an ultralightweight manual wheelchair frame during a portion of the multi-drum test. Occupant mass was varied (80 kg, 125 kg) to reflect standard user weight and maximum weight capacity of the chair. Root-mean-square acceleration and vibration dose values were greatest along the vertical axis, and overall similar for both occupant masses. Comparisons with existing literature suggest that the shocks and vibrations experienced within the multi-drum test far exceed values seen in real-world wheelchair usage. Similarly, frame-based fatigue failures are more common during the multi-drum test. These results suggest that the current test protocol is not well-suited to be an accelerated durability test for manual wheelchairs.
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    Dataset for "Comparison of Propulsion Costs and Vibrations Across Carbon Fiber and Aluminum Rigid Manual Wheelchairs"
    (Georgia Institute of Technology, 2023-09-20) Misch, Jacob ; Allen, Taylor ; Suarez, Alicia ; Sprigle, Stephen
    Propulsion efficiency and vibration exposure are two primary concerns when configuring a manual wheelchair. Recent manufacturing techniques have focused on using lightweight materials like carbon fiber to reduce energy expenditure during propulsion and improve vibration attenuation compared to aluminum or steel frames. This study utilized a robotic wheelchair propulsion device to measure the propulsion cost, vibration exposure at the seat, and vibration transmissibility through the frame during travel over smooth (tile) and textured (brick) surfaces for four rigid ultra-lightweight manual wheelchairs made of carbon fiber (N=1) and aluminum (N=3). Component selection (wheels, tires, casters, cushion) and the robotic occupant parameters (weight, fore-aft weight distribution, propulsion characteristics) were standardized across all four frames. Results show no meaningful differences between the carbon fiber and aluminum frames in any of the three variables (i.e., 95% CI does not fully exceed ±5% for propulsion cost or ±6% for vibration and transmissibility). These findings imply that other frame design features are more impactful to vibrations and propulsion efficiency than the material selection. Minimizing wheelchair vibration exposure and maximizing propulsion efficiency are more easily achieved through considerate selection of components, especially cushions and tires, respectively.