Inelastic collisions of ultra-cold heteronuclear molecules in an optical trap

Ultra-cold RbCs molecules in high-lying vibrational levels of the a$^3\Sigma^+$ ground electronic state are confined in an optical trap. Inelastic collision rates of these molecules with both Rb and Cs atoms are determined for individual vibrational levels, across an order of magnitude of binding energies. A simple model for the collision process is shown to accurately reproduce the observed scattering rates

Piloting an Oral History Approach to Investigate Cancer Perspectives Among Residents of Appalachian Kentucky

Introduction: Kentucky ranks first in the U.S. in overall cancer incidence and mortality rates. Areas of the state that fall within the Appalachian Region, along Kentucky’s eastern border, experience disproportionately high rates of cancer compared to non-Appalachian counties. Purpose: This pilot study investigates whether oral history interviews can be used to understand perspectives on cancer among residents of Appalachian Kentucky. Methods: In 2020, participants (n = 5) who identified as being from and/or having strong connections to Appalachian Kentucky were recruited to participate in this pilot study. Participants included individuals working in cancer-related fields, oncology professionals, and those with personal cancer experience. Using an oral history approach, subjects were asked about challenges within Appalachia that contribute to high rates of cancer regionally. Interviews were analyzed using qualitative content analysis, and data were condensed into themes, subthemes, and subtopics. Relational content analysis was then used to illustrate relationships between the problems being faced in Appalachia and their contributing factors, with potential solutions to those problems. Results: Six key themes emerged from analysis of the oral history interviews: (1) problems being faced in Appalachia; (2) contributing factors; (3) potential solutions; (4) Appalachian disposition; (5) experiences with and thoughts on cancer; and (6) defining success v. the future without changes (intervention). A further 25 subthemes were identified from within these themes. Taken together, these themes and subthemes point to potential areas for specific intervention to shift Appalachia’s cancer burden. Implications: This pilot study demonstrates potential benefit in using oral history interviews to elucidate Appalachian Kentuckians’ perspectives on cancer. From the nuanced insights gained through this method, a set of culturally appropriate interventions were identified that could address the disproportionate cancer burden in the region. Future studies using an oral history approach could aim to reveal other specific aspects of how cancer impacts individuals, families, and communities

The Structural Hierarchy and Mechanical Properties of Fibrin Described with a Multi-scale Model

Fibrin networks form the structural scaffold of blood clots during hemostasis. To survive in the dynamic environment of the vasculature, these networks have a diverse set of mechanical and dynamical properties. In this work, a series of experiments and molecular dynamics simulations bridge the gap between the mechanical properties of fibrin networks and the origins of those properties at the fiber and molecular scales. Mechanical measurements on individual fibrin fibers indicated that fibrin fibers are soft in stretching, strain stiffen, and exhibit an increased stiffness when ligated by transglutaminase FXIIIa. We hypothesized that these properties derived from one particular part of the fibrin molecule, the alpha-C region and developed a mechanical model for the fiber based on the extension of the alpha-C region. Measurements on the recoil dynamics of fibrin fibers indicated that they recoil on microsecond timescales and regain their full tension within a few ms of relaxation in agreement with the alpha-C model. In spite of the success of the alpha-C extension model, the fibrin molecule is complex and several other regions including the coiled coil region and the gamma-nodule have previously been implicated as potential sources of extension. To test these hypotheses we ran constant force Steered Discrete Molecular Dynamics Simulations on each region of the fibrin molecule. The simulations confirmed that the alpha-C region is the most likely to extend at forces as low as 10pN, but implicated other regions of the molecule as well. This led a more complete model for the mechanical properties of individual fibrin fibers dubbed the SLaCK model. Finally, to probe how the mechanical properties of individual fibrin fibers affect network strength, 2-D fibrin networks suspended between channels were stretched to failure using and Atomic Force Microscope. The strain of individual fibers in the network was tracked, and it was shown that fibrin network strength is enhanced by the strain stiffening of individual fibrin fibers. This work provides a framework for a predictive model in which the affects from alterations at the molecular level could be observed in the mechanical properties of the higher levels of the hierarchy.Doctor of Philosoph

The impact of attachment anxiety on susceptibility to false memories

Previous research shows that people's attachment styles predict memory functioning. For example, people with relatively insecure attachment styles tend to forget relationship-relevant information, as well as negatively bias their emotional evaluations of interpersonal experiences over time. An emerging body of research has also begun to suggest that attachment anxiety in particular relates to people's propensity to experience false memories. The present dissertation describes two randomized experiments which attempted to examine a causal link between attachment anxiety and false memories. Furthermore, the present studies attempted to isolate whether attachment anxiety causes false memories during memory maintenance or retrieval processes. Participants were primed with either (1) high attachment anxiety, (2) low attachment anxiety, or (3) were not primed prior to retrieval (Study 1) or during maintenance (Study 2). The experimental primes had no main effects on false memories in either study. This may indicate that attachment anxiety does not cause false memories during maintenance or reconstruction. However, future research should explore whether attachment anxiety might cause false memories during encoding processes. Alternatively, it may be the case that the priming paradigms used failed to appropriately manipulate participants' attachment security, which would render the present findings ambiguous. Current procedures for priming attachment security and future directions for studying links between attachment anxiety and false memories are discussed

Microscale structural changes of individual fibrin fibers during fibrinolysis

Fibrinolysis is the enzymatic digestion of fibrin, the primary structural component in blood clots. Mechanisms of fibrin fiber digestion during lysis have long been debated and obtaining detailed structural knowledge of these processes is important for developing effective clinical approaches to treat ischemic stroke and pulmonary embolism. Using dynamic fluorescence microscopy, we studied the time-resolved digestion of individual fibrin fibers by the fibrinolytic enzyme plasmin. We found that plasmin molecules digest fibers along their entire lengths, but that the rates of digestion are non-uniform, resulting in cleavage at a single location along the fiber. Using mathematical modeling we estimated the rate of plasmin arrival at the fiber surface and the number of digestion sites on a fiber. We also investigated correlations between local fiber digestion rates, cleavage sites, and fiber properties such as initial thickness. Finally, we uncovered a previously unknown tension-dependent mechanism that pulls fibers apart during digestion. Taken together these results promote a paradigm shift in understanding mechanisms of fibrinolysis and underscore the need to consider fibrin tension when assessing fibrinolytic approaches.ECU Open Access Publishing Support Fun