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1. Audio Capture Using Piezoelectric Sensors on Vibrating Panel Surfaces

   DiPassio, Tre; Heilemann, Michael C.; Thompson, Benjamin; Bocko, Mark F. (May 2023, 154th Convention of the Audio Engineering Society)

   The microphone systems employed by smart devices such as cellphones and tablets require case penetrations that leave them vulnerable to environmental damage. A structural sensor mounted on the back of the display screen can be employed to record audio by capturing the bending vibration signals induced in the display panel by an incident acoustic wave - enabling a functional microphone on a fully sealed device. Distributed piezoelectric sensing elements and low-noise accelerometers were bonded to the surfaces of several different panels and used to record acoustic speech signals. The quality of the recorded signals was assessed using the speech transmission index, and the recordings were transcribed to text using an automatic speech recognition system. Although the quality of the speech signals recorded by the piezoelectric sensors was reduced compared to the quality of speech recorded by the accelerometers, the word-error-rate of each transcription increased only by approximately 2% on average, suggesting that distributed piezoelectric sensors can be used as a low-cost surface microphone for smart devices that employ automatic speech recognition. A method of crosstalk cancellation was also implemented to enable the simultaneous recording and playback of audio signals by an array of piezoelectric elements and evaluated by the measured improvement in the recording’s signal-to-interference ratio. 

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2. Dynamic Response of Surface‐Bound Peptides to a pH Perturbation Under Controlled Electrostatic Conditions

   https://doi.org/10.1002/marc.202200635  

   Moonitz, Sasha A.; Noriega, Rodrigo (June 2023, Macromolecular Rapid Communications)

   Abstract The dynamic conformations of a thin peptide film covalently‐linked to the surface of a transparent electrode are characterized over the course of a perturbation to their local pH by a photoacid under a controlled electrostatic potential. The local environment at this functionalized electrified interface is probed by the ultrafast fluorescence intensity and transient anisotropy of chromophores sparsely attached to the peptide side chains. A partition of chromophores into two sub‐populations is observed, one buried in the peptide layer and another that is solvent exposed, and their relative contributions to the observed fluorescence signal are affected by both pH and voltage stimuli. The photophysical properties of solvent‐exposed chromophores reveal that while the average conformation of the peptide mat is dictated by the pH of the surrounding electrolyte, their fluctuations are largely determined by the local electrostatic conditions set by the electrode's surface potential. 

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3. Resource modification by ecosystem engineers generates hotspots of stream community assembly and ecosystem function

   https://doi.org/10.5061/dryad.1rn8pk0x5  

   Tumolo, Benjamin (January 2023, Dryad)

   Ecosystem engineers can generate hotspots of ecological structure and function by facilitating the aggregation of both resources and consumers. However, nearly all examples of such engineered hotspots come from long-lived foundation species, such as marine and freshwater mussels, intertidal cordgrasses, and alpine cushion plants, with less attention given to small-bodied, and short-lived taxa. Insects often have rapid life cycles and high population densities and are among the most diverse and ubiquitous animals on earth. Although these taxa have the potential to generate hotspots and heterogeneity comparable to that of foundation species, few studies have examined this possibility. We conducted a mesocosm experiment to examine the degree to which a stream insect ecosystem engineer, the net-spinning caddisfly (Tricoptera:Hydropsychidae), creates hotspots of ecosystem function by facilitating invertebrate community assembly. Our experiment used two treatments: (1) stream benthic habitat with patches of caddisfly engineers present and (2) a control treatment with no caddisflies present. We show that compared to controls, caddisflies increased local resource availability, measured as particulate organic matter (POM) by 43%, ecosystem respiration (ER) by 70%, and invertebrate density, biomass and richness by 96%, 244%, and 72%, respectively. These changes resulted in increased spatial variation of POM by 25%, invertebrate density by 76%, and ER by 29% compared to controls, indicating a strong effect of caddisflies on ecological heterogeneity. We found a positive relationship between invertebrate density and ammonium concentration in the caddisfly treatment, but no such relationship in the control, indicating that either caddisflies themselves or the invertebrate aggregations they create increased nutrient availability. When accounting for the amount of POM, caddisfly treatments increased invertebrate density by 48% and richness by 40% compared to controls, suggesting that caddisflies may also enhance the nutritional quality of resources for the invertebrate assemblage. The caddisfly treatment also increased the rate of ecosystem respiration as a function of increasing POM compared to the control. Our study demonstrates that insect ecosystem engineers can generate heterogeneity by concentrating local resources and consumers, with consequences for carbon and nutrient cycling. 

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4. Resource modification by ecosystem engineers generates hotspots of stream community assembly and ecosystem function

   https://doi.org/10.1002/ecy.4052  

   Tumolo, Benjamin B.; Albertson, Lindsey K.; Cross, Wyatt F.; Poole, Geoffrey C.; Davenport, Grace; Daniels, Melinda D.; Sklar, Leonard S. (May 2023, Ecology)

   Abstract Ecosystem engineers can generate hotspots of ecological structure and function by facilitating the aggregation of both resources and consumers. However, nearly all examples of such engineered hotspots come from long‐lived foundation species, such as marine and freshwater mussels, intertidal cordgrasses, and alpine cushion plants, with less attention given to small‐bodied and short‐lived animals. Insects often have rapid life cycles and high population densities and are among the most diverse and ubiquitous animals on earth. Although these taxa have the potential to generate hotspots and heterogeneity comparable to that of foundation species, few studies have examined this possibility. We conducted a mesocosm experiment to examine the degree to which a stream insect ecosystem engineer, the net‐spinning caddisfly (Tricoptera:Hydropsychidae), creates hotspots by facilitating invertebrate community assembly. Our experiment used two treatments: (1) stream benthic habitat with patches of caddisfly engineers present and (2) a control treatment with no caddisflies present. We show that compared to controls, caddisflies increased local resource availability measured as particulate organic matter (POM) by 43%, ecosystem respiration (ER) by 70%, and invertebrate density, biomass, and richness by 96%, 244%, and 72%, respectively. These changes resulted in increased spatial variation of POM by 25%, invertebrate density by 76%, and ER by 29% compared to controls, indicating a strong effect of caddisflies on ecological heterogeneity. We found a positive relationship between invertebrate density and ammonium concentration in the caddisfly treatment, but no such relationship in the control, indicating that either caddisflies themselves or the invertebrate aggregations they create increased nutrient availability. When accounting for the amount of POM, caddisfly treatments increased invertebrate density by 48% and richness by 40% compared to controls, suggesting that caddisflies may also enhance the nutritional quality of resources for the invertebrate assemblage. The caddisfly treatment also increased the rate of ecosystem respiration as a function of increasing POM compared to the control. Our study demonstrates that insect ecosystem engineers can generate heterogeneity by concentrating local resources and consumers, with consequences for carbon and nutrient cycling. 

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5. College Geometry from an Advanced Historical Standpoint for Mathematics Education

   Ekici, C. (July 2023, History and Epistemology in Mathematics Education- Proceedings of the 9th European Summer University)

   E. Barbin, R. Capone (Ed.)

   Following Felix Klein, an advanced historical standpoint is here presented for teaching college geometry for teachers. Three main ways of developing an advanced historical standpoint are discussed with classroom experiments. One is building connections among geometries by developing an inquiry into definitions of geometric objects such as rhombus, their extensibility with their family relationships across Euclidean and non-Euclidean geometries. Second is on the multiplicity and extensibility of transformations as represented by two historical approaches advocated by Klein and Usiskin. The third way to develop an advanced standpoint is by developing a critical look into a geometry practice tracing its change with the reforms in school geometry. The practice of constructions to connect geometry and algebra is impacted by two historical efforts. One is a supportive effort by Hilbert on the practice of constructions by Hilbert’s Algebra of Segments dating back to 1902 to connect geometry and algebra. The other historical reform effort is by School Mathematics Study Groups (SMSG) during 1960s, which led to weakening the axiomatic foundations of the practice of constructability and exactness. The case of SMSG’s angle construction axiom is criticized in their revision of axiomatic foundations of school geometry. Three approaches to develop an advanced standpoint informing research and practice of geometry teacher education towards a more historically connected stance. 

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