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Control System Development to Improve Outcomes in Policing of Gun Crimes
No full textLaw enforcement officials struggle to identify perpetrators of shootings quickly, reliably, and effectively. Data indicates that certain areas are more prone to shootings. Most shootings occur in dense urban areas that makes it difficult to discern relevant individuals related to a shooting and perpetrators of shootings often flee the scene of the crime. We created a cost effective control system that rapidly and accurately identifies individuals in the area in which a gunshot is fired. In order to accomplish this, we integrate existing acoustic sensor technology with cellular phone identification techniques. The acoustic sensors detect and distinguish gunshots and then accurately pinpoint the location of the shooting. This location is then utilized by a IMSI (International Mobile Subscriber Identifier) catching system to record all the cellphones in the area of the shooting. After getting a warrant, law officials are then able to link these IMSIs to individuals in order to interrogate further suspects and have clearer suspects. This integrated system would be installed in areas where shootings are more common to both deter gun crimes and aid law enforcement officials in mitigating and identifying perpetrators
Crystallinity and Topology in Organic Materials: From Crystalline Frameworks to Polymer Networks
No full textDesigning organic materials with precisely controlled functions remains a central challenge in chemistry and materials science. Two important classes of organic materials are polymer networks and crystalline frameworks. Although they exhibit fundamentally different morphologies and synthesis routes, they share some structural principles that govern their behaviors. This thesis explores two of these key principles: crystallinity and topology, and their roles in controlling structure–property relationships.
To address the challenge of achieving high crystallinity in stable organic frameworks, we developed a synthetic strategy to construct hydrogen-bonded crosslinked organic frameworks (H\textsubscript{C}OFs). These materials are formed by assembly of hydrogen-bonding motifs followed by single-crystal-to-single-crystal covalent crosslinking, enabling the combination of large pores, enhanced stability, and high single-crystallinity. The unique topology formed by hydrogen bonding and covalent crosslinking endows the resulting frameworks with the abililty to retain long-range order during guest-induced expansion/contraction. This work in Chapter 2 establishes a platform for creating dynamic crystalline frameworks with tunable porosity and robustness.
Crystallinity and topology in polymer systems were investigated through the lens of entanglements and interfacial compatibilization. Using coarse-grained molecular dynamics simulations, we examined how interfacial incompatibility and block copolymer compatibilizers affect crystallization and mechanical response (Chapters 3–4). The results show that entanglement density and chain architecture play decisive roles in determining stress transmission and interfacial strength, while block copolymers can modulate both local crystallinity and failure mechanisms by bridging interfaces and introducing topological constraints.
Finally, we initiated the development of a united-atom simulation framework to model the crystallization of recyclable, polyethylene-mimic aliphatic polyesters (Chapter 5). Preliminary studies reveal the relationship between layer packing and chain architecture, suggesting a direct link between molecular structure and mesoscale ordering. Ongoing work aims to establish structure–property correlations for these sustainable semicrystalline polymers.
Together, these studies demonstrate that crystallinity and topology are unifying design principles for both organic frameworks and polymer networks. By demonstrating how molecular packing and connectivity control structure and dynamics across these systems, this thesis provides insight that may inform the rational design of multifunctional organic materials
Translating Neurophysiological Recordings into Dynamic Estimates of Conceptual Knowledge and Learning
No full textIn our research, we wanted to explore whether we could track how people learn concepts in real-time by combining brain recordings with computational models of conceptual content. Our core question was: can we measure moment-by-moment learning as it happens in someone\u27s brain?
To investigate this, we had 42 participants watch Khan Academy lectures on Earth Formation and Plate Tectonics while we recorded their brain activity using 64-channel EEG. We then created 90 quiz questions across three categories--Earth Formation, Plate Tectonics, and General Geology--to test what they actually learned from the videos. We used topic modeling, a computational technique, to extract and track the conceptual content from the video transcripts, allowing us to see how different concepts evolved throughout the lectures. We also calculated Inter-Subject Functional Correlation (ISFC), which essentially measures how synchronized participants\u27 brain responses were during different parts of the videos. By aligning these brain synchronization patterns with our conceptual trajectories, we could explore whether brain activity patterns could predict learning outcomes.
Our findings were promising. We discovered that brain activity patterns, particularly in the gamma frequency band, differed significantly between questions that participants answered correctly versus incorrectly. This approach successfully linked specific moments in the lectures to learning outcomes, demonstrating that EEG signals can indeed help us track knowledge acquisition as it unfolds. Moving forward, we aim to leverage these brain-based learning signals to develop personalized, adaptive educational tools that could adjust teaching in real-time based on a student\u27s ongoing brain activity.https://digitalcommons.dartmouth.edu/wetterhahn_2025/1019/thumbnail.jp
Rotors, Not Propellers: A Tribute to a Dedicated Helicopter Pilot
Full text linkA tribute to Carl J. Svenson, a pilot who for three decades flew supplies to huts and shelter sites for the Appalachian Mountain Club before his death in a crash in Croyden, New Hampshire, in October 2023
Debacle on Mount Pierce: A Self-Rescue Story
Full text linkTwo friends take a wrong turn heading down Mount Pierce in New Hampshire’s White Mountains, navigating several errors of judgement
