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Building Bridges Through Talk:Exploring Intergroup Dialogue to Strengthen Weak Ties in Polarized Democracies
No full textThis dissertation explores how intergroup dialogue can (re)build bridging social capital in democracies increasingly divided by polarization. Grounded in Allport’s (1954) contact hypothesis—which suggests that intergroup contact fosters mutual understanding under specific conditions —it examines how individuals from diverse backgrounds bridge divides on issues and identities, and create a safe space for constructive dialogues on contentious issues. Departing from traditional studies that rely on controlled settings or retrospective accounts, this research analyzes real-time behaviors using rare recordings of intergroup dialogues in natural civil society contexts. This approach provides a rich, nuanced understanding of what unfolds during these exchanges, revealing strategies and dynamics that help bridge divides and reduce polarization.Chapter I sets the stage by introducing the study’s context, key concepts, and research assumptions. Chapter II lays the theoretical foundation, linking social capital and dialogue studies. It illustrates how intergroup dialogue can be a powerful tool for developing bridging social capital and emphasizes the role of context - purpose, places, people, and processes - in building relationships across divides. Chapters III and IV explore how participants navigate differences in issues and identities during divisive discussions to foster understanding and relations. Chapter III analyzes dialogues on race after the Charlottesville riots, showcasing the complex interplay between issues, identities, and cultural contexts in promoting healing and reconciliation. Chapter IV examines rare constructive conversations among polarized U.S. political elites, revealing how embracing complexity over binary viewpoints and prioritizing strategies that bridge rather than deepen divides, can reduce both issue-based and identity-based polarization. Chapter V examines community dialogues during the Black Lives Matter protests and the COVID-19 pandemic, emphasizing participants’ active roles in creating and sustaining “safe spaces” for meaningful dialogue. It highlights the paradox of creating safe spaces, requiring both the safety from risk and courage to take risks by openly engaging with opposing or controversial views and showing personal vulnerability. Chapter VI synthesizes the findings, explores implications, addresses limitations, and outlines future directions. Together, these studies reveal the transformative power of intergroup dialogue to (re)build connections and promote unity, even in deeply divided democracies.<br/
BEAM-ALIGN:Distributed user association for mmWave networks with multi-connectivity
No full textSince the spectrum below 6 GHz bands is insufficient to meet the high bandwidth requirements of 5G use cases, 5G networks expand their operation to mmWave bands. However, operation at these bands has to cope with a high penetration loss and susceptibility to blocking objects. Beamforming and multi-connectivity (MC) can together mitigate these challenges. But, to design such an optimal user association scheme leveraging these two features is non-trivial and computationally expensive. Previous studies either considered a fixed MC degree for all users or overlooked beamforming. Driven by the question what is the optimal degree of MC for each user in a mmWave network, we formulate a user association scheme that maximizes throughput considering beam formation and MC. Our numerical analysis shows that there is no one-size-fits-all degree of optimal MC; it depends on the number of users, their rate requirements, locations, and the maximum number of active beams at a BS. Based on the optimal association, we design BEAM-ALIGN: an efficient heuristic with polynomial-time complexity O(|U|log|U|), where |U| is the number of users. Moreover, BEAM-ALIGN only uses local BS information - i.e. the received signal quality at the user. Differing from prior works, BEAM-ALIGN considers beamforming, multiconnectivity and line-of-sight probability. Via simulations, we show that BEAM-ALIGN performs close to optimal in terms of per-user capacity and satisfaction while it outperforms frequently-used signal-to-interference-and-noise-ratio based association schemes. We then show that BEAM-ALIGN has a robust performance under various challenging scenarios: the presence of blockers, rain, and clustered users.</p
[18F]-Labeled Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography in Staging and Restaging Patients With Breast Cancer
No full text1169 Association Between Sleep Disturbance and Pain-Related Outcomes Among Former Professional American-style Football Players
No full textIntroduction: Sleep disturbances and chronic pain frequently co-occur, exhibiting a bidirectional relationship that exacerbates both conditions. Former professional American-style football (ASF) players face unique health challenges from the physical demands and injuries sustained during their careers. This study investigates the associations between sleep disturbances and pain-related outcomes in this high-risk population.Methods: This cross-sectional study analyzed data from 111 former professional ASF players enrolled in the Football Players Health Study at Harvard University. Sleep disturbance and sleep-related impairment were measured using PROMIS T-scores, while sleep-disordered breathing (SDB) was assessed using a single-night apnea-hypopnea index (AHI >15 events/hour). Pain outcomes included PROMIS pain interference T-scores and a 0–10 numeric rating scale for pain intensity. Weighted multivariable linear regression models were employed to evaluate associations, adjusting for demographics, physical activity, smoking status, football position, and number of professional seasons, to generalize findings to the broader Football Players Health Study cohort.Results: The mean age of the former professional ASF players was 48.2 ± 7.8 years; 59 (53.2%) identified as Black, and 52 (46.8%) as White. The average duration of professional league play was 4.0 years, and 62 (55.9%) primarily played lineman positions. Higher PROMIS sleep disturbance scores were associated with higher pain interference (multivariable model β = 0.47; 95% CI: 0.16, 0.79; p < 0.01) and higher pain intensity (β = 1.03; 95% CI: 1.00, 1.06; p = 0.02). Similarly, sleep-related impairment scores were significantly associated with higher pain interference (β = 0.69; 95% CI: 0.43, 0.96; p < 0.001) and pain intensity (β = 1.05; 95% CI: 1.03, 1.07; p < 0.001). No significant associations were observed between SDB or higher rapid eye movement (REM) sleep percentage and pain intensity (β = 1.12, 95% CI: 0.70, 1.81, p = 0.63; β = 1.02, 95% CI: 0.98, 1.05, p = 0.34).Conclusion: Patient-reported sleep disturbances and sleep-related impairment are significantly associated with higher pain interference and higher pain intensity among former professional ASF players. These findings underscore the opportunity for interventions to address sleep disturbances as part of comprehensive pain management strategies to reduce symptom burden and improve quality of life in this population
Ultrasound documentation principles in rheumatology practice and research
No full textIn Chapter 1, we have demonstrated how to write an ultrasound request. In this chapter, we focus on various other aspects of ultrasound principles in clinical practice and research. The documentation of ultrasound in rheumatology practice includes the referral request, patient details, indications and details of the examination and findings, as well as the preliminary and final reports; before these reports are finalized, communication among the team is required and should be documented. Reports should be given within twenty-four hours or on the next business day. Quality assessments, including cleanliness and safety of the equipment and performance, should be performed periodically by sonographers in partnership with physicians, medical physicists, and biomedical engineers. As Low As Reasonably Achievable (ALARA) principle could prevent adverse bioeffects without lowering image quality. Dissemination of infection within the ultrasound environment should be prevented with low- and high-level disinfection, and internal transducers always require high-level disinfection. Ultrasound reporting in research should follow some recommended guidelines; in the latter half of the chapter, we focus on the EULAR (European Alliance of Associations for Rheumatology) ultrasound checklist to be used for documentation in rheumatology research.</p
Assessing DIEP flap perfusion using handheld wireless laser speckle contrast imaging:A proof of principle study
No full textBackground: In reconstructive surgery, adequate perfusion of flaps is essential for successful outcomes. Assessing normal flap perfusion and differentiating it from problematic perfusion is important and time-consuming. Laser speckle contrast imaging (LSCI), an optical technique for quantitative microcirculation assessment, can be used to non-invasively monitor flap perfusion. We designed a wireless handheld LSCI device and investigated its clinical feasibility in Deep Inferior Epigastric Perforator (DIEP) flap reconstruction surgery.Methods: In a case series study with 15 patients and 20 DIEP flaps, perfusion was measured perioperatively across the 4 Hartrampf zones at 4 specific time points and on the first post-operative day. Results: In unilateral reconstructions, the perfusion in dissected flaps showed a perfusion gradient across the zones, with the highest perfusion in zone I and lowest perfusion in zone IV. The decrease in perfusion between unilateral flap elevation and temporary occlusion measurements was detected in unilateral flaps, but not in bilateral flaps. The device could detect flap failure in 2 cases by measuring anomalous perfusion values. Conclusions: The results indicate that our device is potentially valuable for flap monitoring. It detected differences in perfusion throughout the flap zones, a decrease in perfusion when clamping the pedicle and anomalous perfusion in flaps that failed. Motion artefact correction is needed to measure reliably during motion caused by patient breathing, pulse and operator motion. Further studies are needed to determine whether the wireless perfusion imager enables the early detection of complications, which could aid in prevention or prompt reintervention to salvage a flap.</p
A geometrically non-linear beam theory for active beams with arbitrary cross-section
No full textNon-linear active beam theories can be used to model many types of prismatic structures that contain piezoelectric material. In this work, we show that the 3D governing continuum equations of active prismatic structures loaded only at their ends can, without any simplifying assumptions on the stress state or geometry of the cross-section, be decomposed into a large deflection active beam theory and deformation modes that exponentially decay in magnitude from both ends of the prismatic structure. This is a manifestation of Saint-Venant’s principle for active beams, where the contribution of the decaying solutions is only relevant near the ends of the beam and can thus be safely neglected if the structure is significantly longer than the dominant decay length. A finite element discretisation of the cross-section is used to handle arbitrary prismatic geometry. By directly discretising the cross-sectional Hamiltonian, the beam constitutive coefficients of the large deflection beam theory can be found efficiently by solving a sparse system of equations. Furthermore, the dominant decay length of the exponentially decaying solutions can be estimated with limited computational effort. The approach is validated against analytical solutions, other numerical cross-section analysis approaches and the 3D finite element software COMSOL for various validation cases
Controlling Grain Boundary Segregation to Tune the Conductivity of Ceramic Proton Conductors
No full textAcceptor-doped barium zirconates are of major interest as proton-conducting ceramics for electrochemical applications at intermediate operating temperatures. However, the proton transport through polycrystalline microstructures is hindered by the presence of a positive space charge potential at grain boundaries. During high-temperature sintering, the positive charge acts as a driving force for acceptor dopant segregation to the grain boundary. Acceptor segregation to grain boundaries has been observed in sintered ceramics, but the fundamental relationship between the segregation kinetics and the protonic conductivity is poorly understood. Here, a comprehensive study of the influence of acceptor dopant segregation on the electrochemical properties of grain boundaries in barium zirconate ceramics is presented. An out-of-equilibrium model material that displays no detectable Y segregation at its grain boundaries is explicitly designed. This model material serves as a starting point to measure the kinetics of segregation and the induced changes in grain boundary conductivity upon varying thermal histories. Furthermore, the electrochemical results from impedance spectroscopy to atomic resolution transmission electron microscopy, atom probe tomography, and DFT simulations are correlated. It is discovered that acceptor dopant segregation drastically increases the proton conductivity in both the model system and several other application-relevant compositions
Structural Distortions Control Scaling of Exciton Binding Energies in Two-Dimensional Ag/Bi Double Perovskites
No full textThree-dimensional metal halide double perovskites such as CsAgBiBr exhibit pronounced excitonic effects due to their anisotropic electronic structure and chemical localization effects. Their two-dimensional derivatives, formed by inserting organic spacer molecules between perovskite layers, were expected to follow well-established trends seen in Pb-based 2D perovskites, namely, increasing exciton binding energies with decreasing layer thickness due to enhanced quantum and dielectric confinement. However, recent experimental and computational studies have revealed anomalous behavior in Ag/Bi-based 2D perovskites, where this trend is reversed. Using ab initio many-body perturbation theory within the and Bethe-Salpeter Equation frameworks, we resolve this puzzle by systematically comparing experimental structures with idealized models designed to isolate the effects of octahedral distortions, interlayer separation, and stacking. We find that structural distortions, driven by directional Ag d orbital bonding, govern the momentum-space origin and character of the exciton, and are the primary cause of the observed non-monotonic trends. Furthermore, we explore how interlayer distance and stacking influence band gaps and exciton binding energies, showing that, despite different chemistry, the underlying confinement physics mirrors that of Pb-based 2D perovskites. Our results establish design principles for tuning excitonic properties in this broader class of layered, lead-free materials
FedOpenHAR:Federated Multitask Transfer Learning for Sensor-Based Human Activity Recognition
No full textWearable and mobile devices equipped with motion sensors offer important insights into user behavior. Machine learning and, more recently, deep learning techniques have been applied to analyze sensor data. Typically, the focus is on a single task, such as human activity recognition (HAR), and the data is processed centrally on a server or in the cloud. However, the same sensor data can be leveraged for multiple tasks, and distributed machine learning methods can be employed without the need for transmitting data to a central location. In this study, we introduce the FedOpenHAR framework, which explores federated transfer learning in a multitask setting for both sensor-based HAR and device position identification tasks. This approach utilizes transfer learning by training task-specific and personalized layers in a federated manner. The OpenHAR framework, which includes ten smaller datasets, is used for training the models. The main challenge is developing robust models that are applicable to both tasks across different datasets, which may contain only a subset of label types. Multiple experiments are conducted in the Flower federated learning environment using the DeepConvLSTM architecture. Results are presented for both federated and centralized training under various parameters and constraints. By employing transfer learning and training task-specific and personalized federated models, we achieve a higher accuracy (72.4%) compared to a fully centralized training approach (64.5%), and similar accuracy to a scenario where each client performs individual training in isolation (72.6%). However, the advantage of FedOpenHAR over individual training is that, when a new client joins with a new label type (representing a new task), it can begin training from the already existing common layer. Furthermore, if a new client wants to classify a new class in one of the existing tasks, FedOpenHAR allows training to begin directly from the task-specific layers.</p