150813 research outputs found
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Shift invariance of half space integrable models
No full textWe formulate and establish symmetries of certain integrable half space models, analogous to recent results on symmetries for models in a full space. Our starting point is the colored stochastic six vertex model in a half space, from which we obtain results on the asymmetric simple exclusion process, as well as for the beta polymer through a fusion procedure which may be of independent interest. As an application, we establish a distributional identity between the absorption time in a type B analogue of the oriented swap process and last passage times in a half space, establishing the Baik–Ben Arous–Péché phase transition for the absorption time. The proof uses Hecke algebras and integrability of the six vertex model through the Yang–Baxter and reflection equations
Search for long-lived heavy neutral leptons in proton-proton collision events with a lepton-jet pair associated with a secondary vertex at √s = 13 TeV
No full textA search for long-lived heavy neutral leptons (HNLs) using proton-proton collision data corresponding to an integrated luminosity of 138 fb−1 collected at s = 13 TeV with the CMS detector at the CERN LHC is presented. Events are selected with a charged lepton originating from the primary vertex associated with the proton-proton interaction, as well as a second charged lepton and a hadronic jet associated with a secondary vertex that corresponds to the semileptonic decay of a long-lived HNL. No excess of events above the standard model expectation is observed. Exclusion limits at 95% confidence level are evaluated for HNLs that mix with electron and/or muon neutrinos. Limits are presented in the mass range of 1–16.5 GeV, with excluded square mixing parameter values reaching as low as 2 × 10−7. For masses above 11 GeV, the presented limits exceed all previous results in the semileptonic decay channel, and for some of the considered scenarios are the strongest to date
Multiscale design of bioadhesive platforms for next-generation applications in surgery and healthcare
No full textBioadhesives—materials capable of adhering to biological tissues—hold significant promise as transformative tools in healthcare, offering the ability to repair tissues with ease and minimal damage. These materials present numerous opportunities in surgery and human-machine interfaces, creating a broad landscape of applications that has captivated clinical and scientific interest alike. Still, there remain open challenges surrounding their reliability, biocompatibility, usability, and versatility. These include weak adhesion with wet tissues, foreign body response, cumbersome application processes, and limited customizability. This dissertation presents a multiscale framework for addressing these obstacles, encompassing design strategies on the molecular, polymer network architecture, macroscale device, and application process levels. The implementation of this framework is demonstrated through the development of two pioneering bioadhesive platforms: (1) a multifunctional patch for minimally invasive surgery, and (2) a 3D printable bioadhesive for fabricating tunable, application-specific devices. Together, these platforms expand the design space for creating robust and versatile tissue repair solutions and biomedical devices.Ph.D
Energy Burden in the United States: An Analysis Using Decision Trees
No full textThe concept of energy burden (EB) continues to gain prominence in energy and associated policy research as energy prices rise and electricity and heating options diversify. This research offers a deeper understanding of EB dynamics and how EB can be addressed more effectively by discerning the interplay between regional environmental, social, and economic factors. Using decision trees (DTs), a powerful machine learning technique, we explore the multifaceted dynamics that shape EB across the United States (U.S.) by examining how factors like housing quality, demographic variations, access to energy sources, and regional economic conditions interact, creating distinct EB profiles across communities. Following a comprehensive review of existing literature and DT analysis, we map the results to identify the most significant factors influencing EB. We find that no single variable has a determinant effect on EB levels. While there is no uniform regional pattern, regions with higher population density exhibit a stronger correlation between EB and socioeconomic and other demographic factors such as educational attainment levels and racial segregation. Our findings underscore the significance of regional ecologies in shaping EB, revealing how localized environmental and economic contexts amplify or mitigate systemic inequities. Specifically, our analysis reveals significant regional disparities, highlighting the need for localized policies and interventions. We find that a one-size-fits-all approach is insufficient and that targeted, place-based strategies are necessary to address the specific needs of different communities. Policy interventions should prioritize energy democracy, address systemic inequities, and ensure universal energy access through participatory planning, financial assistance, and targeted initiatives such as housing rehabilitation, energy efficiency improvements, and incentives for underrepresented communities
SonicHoop: Using Interactive Sonification to Support Aerial Hoop Practices
No full textCHI ’21, May 8–13, 2021, Yokohama, JapanAerial hoops are circular, hanging devices for both acrobatic exercise and artistic performance that let us explore the role of interactive sonification in physical activity. We present SonicHoop, an augmented aerial hoop that generates auditory feedback via capacitive touch sensing, thus becoming a digital musical instrument that performers can play with their bodies. We compare three sonification strategies through a structured observation study with two professional aerial hoop performers. Results show that SonicHoop fundamentally changes their perception and choreographic processes: instead of translating music into movement, they search for bodily expressions that compose music. Different sound designs affect their movement differently, and auditory feedback, regardless of type of sound, improves movement quality. We discuss opportunities for using SonicHoop as an aerial hoop training tool, as a digital musical instrument, and as a creative object; as well as using interactive sonification in other acrobatic practices to explore full-body vertical interaction
Computer‐aided evaluation and exploration of chemical spaces constrained by reaction pathways
No full textThe processes of molecular design and synthetic route selection are necessarily intertwined during discovery. Computational tools have been developed to facilitate synthesis planning, but in a discovery setting, finding a single route to a single molecule of interest may be less important than finding a route that enables rapid access to a library of analogs. Here, we demonstrate how we can estimate route “diversifiability” and use it as a criterion during route selection. We illustrate how the chemical space of synthetically accessible analogs is influenced by properties of alternative starting materials or constraints on their cost. Finally, we integrate these analyses with a synthesizability‐constrained hit expansion workflow in a virtual screening pipeline for focused library expansion around putative hits to support molecular optimization. As medicinal chemistry and adjacent fields shift toward more autonomous design and synthesis of new molecules, it will be increasingly important to embed considerations of synthesizability into molecular design to ensure that computational recommendations are actionable
Design and Validation of a High-Fidelity Left Atrial Cardiac Simulator for the Study and Advancement of Left Atrial Appendage Occlusion
No full textPurpose Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia that increases the risk of stroke, primarily due to thrombus formation in the left atrial appendage (LAA). Left atrial appendage occlusion (LAAO) devices offer an alternative to oral anticoagulation for stroke prevention. However, the complex and variable anatomy of the LAA presents significant challenges to device design and deployment. Current benchtop models fail to replicate both anatomical variability and physiological hemodynamics, limiting their utility. This study introduces a novel left atrial cardiac simulator that incorporates patient-derived LAA models within a benchtop circulatory flow loop, enabling high-fidelity LAAO device testing and development. Methods A rigid, patient-derived left atrium (LA) model was 3D printed from segmented MRI data and modified to accommodate attachment of patient-specific LAA models. A library of LAA geometries was fabricated using silicone casting techniques to replicate the mechanical properties of native tissue. The LA-LAA model was integrated into a circulatory flow loop equipped with a pulsatile pump, pressure sensors, and flow probes, allowing real-time hemodynamic analysis. System tunability was demonstrated by varying heart rate, stroke volume, resistance, and compliance to simulate physiological and pathological conditions. Results The simulator accurately replicated LA pressure and flow waveforms, closely approximating physiological conditions. Changes in heart rate, stroke volume, and compliance effectively modulated LAP and LA inflow before and after LAAO. Distinct pressure and flow waveforms were observed with different LAA geometries. Hemodynamic analysis revealed increased left atrial pulse pressure after occlusion, with the greatest increase occurring after complete exclusion of the LAA. The simulator facilitated the evaluation of LAAO device performance, including metrics such as seal and PDL, and served as an effective training tool for iterative device deployment and recapture with visual and imaging-guided feedback. Conclusions The left atrial cardiac simulator offers a highly tunable and realistic platform for testing and developing LAAO devices. It also serves as an effective procedural training tool, allowing for the simulation of patient-specific anatomical and hemodynamic conditions. By enabling these advanced simulations, the simulator enhances pre-procedural planning, device sizing, and placement. This innovation represents a significant step toward advancing personalized medicine in atrial fibrillation management and improving LAAO outcomes
Going with our Guts: Potentials of Wearable Electrogastrography (EGG) for Affect Detection
No full textICMI ’20, October 25–29, 2020, Virtual Event, Netherland
Design and Evaluation of a Powered Series-Elastic Cycloidal Ankle (CyAn) Prosthesis
No full textThe prevalence of major lower limb loss in the United States is projected to increase significantly due to rising rates of diabetes and obesity, highlighting an urgent need for advanced prosthetic solutions [1]. Individuals with lower limb amputations often face increased energy expenditure and secondary musculoskeletal conditions as a result of using conventional prosthetic devices [2]. These challenges underscore the necessity for innovative prosthetic designs that can enhance user mobility and comfort. A promising prosthesis solution are powered ankle-foot prostheses, which have the potential to provide biologically accurate push-off power, thereby offering significant benefits such as improved walking economy, increased mobility, and reduced impact forces on the user’s residual limb. However, existing powered prostheses often lack customization and fail to adequately meet the diverse and specific needs of individual users, which can limit their effectiveness and adoption. This thesis introduces a personalized, optimized, low-profile powered ankle-foot prosthesis, known as the Cycloidal Ankle (CyAn), designed to achieve biological ranges of motion and torque during level-ground walking. The CyAn employs a cycloidal drive transmission and a series carbon fiber spring to mimic tendon-like compliance, which enhances energy storage and return while maintaining a low build height to accommodate a broader range of users. The prosthesis device is capable of 25◦ of dorsiflexion and 41◦ of plantarflexion, and is capable of outputting at least 130 Nm of torque during walking, corresponding to biological ankle torque during level ground walking at 1.5 m/s for a 50th percentile male [3]. The CyAn prosthesis uses of a cycloidal drive transmission coupled with a series carbon fiber spring. This combination replicates tendon-like compliance and allows for a reduced build height without compromising the prosthesis’s range of motion or mechanical performance. The development of the CyAn prosthesis involved a comprehensive mechanical and mechatronic design process, encompassing modeling, optimization of electrical energy consumption, component selection, and benchtop and clinical evaluation. This thesis describes the detailed design and analysis of the CyAn prosthesis, including a parametric model for predicting device performance, fatigue life calculations, and mechanical integrity assessments of device components. Benchtop testing results confirm that the device successfully achieves the targeted performance metrics, demonstrating its capability to replicate natural gait mechanics. The clinical validation study was conducted with 3 participants with unilateral transtibial amputation at 3 different walking conditions: level ground at 1.5 m/s, uphill (+10◦ slope) at 0.8 m/s, and downhill (-10◦ slope) at 1.2 m/s. During the experiment, the subjects walked on an instrumented treadmill to regulate the walking speed while force and motion data were recorded. The results of these tests demonstrate the prosthesis design’s capability to replicate natural gait mechanics and kinetics, as well as insights into further improvements and adaptations. This thesis comprehensively details the mechanical and mechatronic design processes, encompassing modeling, optimization, component selection, and empirical evaluation of the CyAn prosthesis. This thesis presents the first of its kind rotary powered ankle-foot prosthesis, utilizing a cycloidal drive mechanism and a custom series carbon fiber spring. Compared to existing powered devices, the CyAn offers a lower device mass and increased biomimetic functionality, making it a cost-effective solution for improving mobility and quality of life for transtibial amputees. This research establishes a framework for developing customized prosthetic solutions that address the unique needs of individual users, with significant clinical results demonstrating the potential of the CyAn to improve health outcomes by normalizing biomechanics, increasing energy efficiency, and reducing adverse limb loading.Ph.D
From burst to controlled release: using hydrogel crosslinking chemistry to tune release of micro-crystalline active pharmaceutical ingredients
No full textHydrogels have been widely studied as substrates for drug delivery and tissue engineering owing to their biocompatibility and ability to swell in aqueous media. Encapsulation of lipophilic active pharmaceutical ingredients (API) as crystalline micro-/nanoparticles within hydrogel formulations has shown promise for improving their bioavailability and achieving high drug load. Despite the size reduction of the API within the hydrogel mesh, the bioavailability of these formulations is largely governed by the inherent ability of the hydrogel polymer backbone to release the API. In this work, Michael addition-based Polyethylene glycol (PEG) hydrogels are developed for micro-crystalline fenofibrate (Fen) encapsulation. Using a parallelized step emulsification device, API nanoemulsion (NE) loaded micro-hydrogels are fabricated and subsequently subjected to anti-solvent extraction for API crystallization. The bi-molecular nature of the Michael addition reaction provides modular incorporation of crosslinking functional groups leading to precise temporal control over hydrogel degradation, thereby offering a sensitive handle on the release of micro-crystalline fenofibrate. By merely changing the chemical identity of the hydrogel cross-link, complete Fen release could be tuned from 4 hours to 10 days. Furthermore, the interaction of crystallizing Fen and PEG within the micro-hydrogel environment led to eutectic formation. This unique feature offered a second handle on the Fen release from the composite micro-hydrogels