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Investigation of Arterial Luminal Topography and Design of Crimped Fiber Composites
No full textThe lumen of arteries usually appears corrugated in histological cross-sections. These corrugations occur due to the wrinkling of the Internal Elastic Lamina (IEL) and have often been attributed to fixation artefacts. We quantify the IEL topography and test whether the corrugations are actually present in arteries under physiological conditions. This is done by imaging cross-sections of fixed arteries at different diameters and comparing them to the diameter measured in-vivo using ultrasound. It is seen that the IEL corrugations flatten out as the arterial diameter increases, and the IEL contour length is ~10% more than the circumference at ultrasound diameter. These results provide evidence that the luminal topography is not completely flat under physiological conditions.
Fibrous collagen exists in biological tissues in the form of crimped fibers. This crimped nature of fibers enables them to uncrimp before stretching and provide an increased stiffness as the tissue stretches, thus imparting ‘strain-hardening’ behavior to the tissues. Composites of soft material embedded with short stiffer crimped fibers have the potential to show similar mechanical behavior and have the advantage of being flow processible. Here we study the mechanics of crimped fiber composites by quantifying the stress transfer between a single crimped fiber and a an embedding soft matrix, and examining the mechanical response of crimped multifiber composites under tension, using 3D finite element analysis.
As the composite is stretched, fibers with large crimp amplitude and large relative modulus straighten significantly at small strains without bearing significant load. Thus, crimped fiber composites show a super-linear increase in stress upon tension. Stress-transfer mechanics of a crimped fiber are captured using a shear lag model, where the crimped fiber can be replaced by an equivalent softer straight fiber with increasing strain-dependent modulus. Multifiber composites show that higher fiber volume fraction yields higher reinforcement. Moreover, maximum reinforcement is achieved when the fibers are oriented along the direction of the stretch. Thus, the degree of strain-hardening and the degree of reinforcement of multi-crimped-fiber composites can be tuned by changing fiber parameters to achieve the desired mechanical behavior of the composite
National in Difference: Primary Schooling, Citizen-Subjects, and Imperial Notions in Romanian-Administered Dobruja, 1878-1920
No full textThis dissertation explores the relationship between universal schooling and nation-building in a (purportedly) post-imperial borderland. Building on recent literature on national indifference, which presents borderland actors as culturally and politically fluid, this project shows the nation-state to have been as adaptive as its citizens. Like the communities that attended the Islamic, Bulgarian, German, Greek, Russian, Armenian, French, and Jewish schools in the formerly Ottoman maritime region of Dobruja, the Romanian state constantly evaluated the viability of cultural nationalization. By emphasizing the ambiguity of legal language, the flexibility of regional policies, and the responsiveness of central actors to geopolitical pressures, this project presents the nation-state as a pragmatically agnostic actor that used nationalism much as borderland actors did – strategically and selectively. It argues that the Romanian nation-state governed its composite parts via a dynamic differentiated rule inspired by, and reflective of, imperial norms and strategies of governance. In so doing, this project emphasizes the imperfect and extended transition from a Europe of empires to one of nation-states and dissipates the smoke and mirrors of nationalist rhetoric and legislation to better understand the practical considerations underpinning state-minority interactions within the context of expansionist nation-building
The Historical Persistence of Far-Right Influence in Belgium
No full textHow do far-right populist parties today benefit from the legacy of the past fascist parties? This dissertation reveals a historical connection between contemporary far-right parties with interwar fascist parties. The argument is threefold. First, the historical persistence is an important factor in explaining the success and failure of contemporary far-right parties. Second, the mechanism of historical persistence is the far-right social organizations that could preserve the fascist legacy. Third, the historical contexts, especially the historical narrative, decide whether the far-right social organizations could develop or not. This dissertation uses both quantitative spatial analysis and qualitative historical analysis to investigate the case of Belgium. Belgium is politically divided into Flanders and Wallonia, and the far-right parties are strong in Flanders but weak in Wallonia. This study first demonstrates that the historical persistence of far-right influence exists in Flanders but not in Wallonia. Then this study finds that the major difference between Flanders and Wallonia is the thriving far-right social organization in Flanders, which helped the former fascists preserve their ideology and social connections. Finally, this study reveals that the historical context after the World War II is the key in explaining the development of far-right civil society. The post-war repression against collaborators under the victimization sentiment in Flanders created a favorable historical narrative that facilitated the resurgence of former fascists and the emergence of far-right organizations. This dissertation contributes to our understanding on the success and failure of far-right parties, and provides a nuanced case for the role of civil society on democracy, addressing the importance of historical context
Within Person Associations of Thought Uncontrollability and Negative Valence with Anxiety Symptoms: A Daily Diary Investigation
No full textBackground: Perseverative thought (PT) is a cognitive process involving marked repetitive and uncontrollable mental activity centered on a particular theme. Recently, research investigating the characteristics of PT that vary within person has identified thought uncontrollability and negative valence as characteristics of PT that are strongly related to anxiety-related disorders at the between-person level. Despite findings that thought uncontrollability and negative valence are dissociable dimensional features of PT, no studies have looked at their concurrent or prospective within-person associations with anxiety. This research gap is important to address because major psychological theories of PT propose a specific role for uncontrollability, above and beyond negative valence, in contributing to the adverse effects of PT. Thus, this study uses a prospective longitudinal daily diary design to investigate the independent and incremental within-person associations of thought uncontrollability and negative valence with anxiety symptoms.
Method: Prospective daily-diary measures of thought uncontrollability (hard-to-stop, intrusive, repetitive), negative valence (happy [reversed scored], nervous), and anxiety symptoms were completed by 200 undergraduate students for 15 days. Six multilevel models were conducted to examine the within person associations of thought uncontrollability and negative valence with anxiety symptoms. Two sensitivity analyses examined whether greater thought uncontrollability was differentially associated with specific facets of anxiety (anxious arousal and anxious
apprehension).
Results: Uncontrollability and negative valence were positively associated with same-day anxiety symptoms. Furthermore, uncontrollability was incrementally positively associated with same-day anxiety symptoms beyond negative valence. However, greater uncontrollability did not predict next-day anxiety symptoms. Unexpectedly, greater uncontrollability was related to both higher anxious arousal and higher anxious apprehension within person.
Conclusion: This study suggests that negative valence and uncontrollability are transdiagnostic characteristics of PT that relate to anxiety, but may not prospectively predict anxiety, within person. Future research should directly explore the temporal specificity of how these dimensions of PT relate to anxiety over time
A Community Outreach and Program Evaluation of the Center for Population Health and Cambria-Somerset COVID-19 Task Force
No full textRural areas experience a variety of health disparities and challenges, which community-based public health programs are uniquely positioned to address. Community outreach and stakeholder engagement are key components of public health program evaluation and iteration. This thesis presents a qualitative, formative program evaluation of a community health promotion initiative based in two rural southwestern Pennsylvania counties (Cambria and Somerset). The overall goal of this evaluation is to obtain community members’ feedback on programs and public health outreach efforts in these counties, and to explore how community members’ views contextualize a 2022 Community Health Needs Assessment (CHNA). The evaluator held six listening sessions with adults across Cambria and Somerset Counties, using human-centered design methods to facilitate the discussions. The evaluator used thematic analysis to analyze participant feedback. Comments contextualized the 2022 CHNA with greater detail and nuance, while generally aligning with the topics in the 2022 CHNA. Participants identified several themes that were not independently listed among the seven main priorities of the 2022 CHNA. Participants also identified a need for improved community outreach and help with navigating the health and human service system, a complex topic not prioritized in the 2022 CHNA. The evaluation’s findings will inform future public health program planning and coalition-building and align public health programs with community priorities. The results will assist the Center for Population Health of Johnstown, PA as the organization improves public health outcomes, strives for rural health equity, addresses social determinant of health needs, and responds to the disproportionate impact of COVID-19 in Cambria and Somerset Counties
Variation in Opportunity to Learn at Secondary Education: The Social Determinants of Between- and Within-School STEM Tracking in the US and Beyond
No full textThis dissertation investigates the social determinants of STEM curriculum tracking and changes in the nature of STEM tracking in both US and cross-national settings over recent decades in five NCES High School longitudinal datasets and in seven TIMSS studies. Methodologically, this dissertation contributes to the field by developing a consistent and comprehensive transcript-based and instructional content-based measurement scheme of the most important organizational dimensions of tracking. This research also advances the current state of knowledge in the field of STEM curriculum and education inequality by adding rich description of the organizational dimensions of tracking both in the US and globally and drawing attention to the ways in which STEM curriculum tracking departs from its functional ideal. Although tracking systems are intended to benefit all students, too often they result in widening educational inequality. Using rich data on student course taking over the course of secondary education, I produce new measures at both the school-level and country-level capturing inequality in STEM opportunity to learn, both of which are essential to the STEM pipeline. At the same time, as with prior policy-focused studies, this research project draws attention to tracking policies and practices themselves in hopes of generating organizational awareness of, and introspection by administrators towards tracking. In an era of curriculum intensification, this work helps researchers and policymakers understand how schools with different compositional characteristics expose students to differently tracked learning environments. Moreover, this dissertation study also advocates a systematic understanding of tracing the fundamental sources of inequality in opportunity to learn. Overall, while it may be difficult to describe a given determinant of tracking in the context of the secondary data analyses in this dissertation as unequivocally dysfunctional, this research may nevertheless encourage scrutiny of curricular policy and practice that too often go unexamined
Optimal Entanglement Distillation Policies for Bipartite Quantum Switches
No full textIn an entanglement distribution network, the function of a quantum switch is to generate elementary entanglement with its clients followed by entanglement swapping to distribute end-to-end entanglement of sufficiently high fidelity between clients. The threshold on entanglement fidelity is any quality-of-service requirement specified by the clients as dictated by the application they run on the network.
We consider a discrete-time model for a quantum switch that attempts generation of fresh elementary entanglement with two clients in each time step in the form of maximally entangled qubit pairs, or Bell pairs, which succeed probabilistically; the successfully generated Bell pairs are stored in noisy quantum memories until they can be swapped. We focus on establishing the value of entanglement distillation of the stored Bell pairs prior to entanglement swapping in presence of their inevitable aging, i.e., decoherence: For a simple instance of a switch with two clients, exponential decay of entanglement fidelity, and a well-known probabilistic but heralded two-to-one distillation protocol, given a threshold end-to-end entanglement fidelity, we've employed both the Markov Decision Processes framework and a Reinforcement Learning approach to find optimal policies. This dual approach allows us to address the discrete state space assumptions that constrained the Markov Decision Process Model.
By integrating Reinforcement Learning, we aim to enhance our model's flexibility. With these combined methodologies, our goal is to pinpoint the optimal action policy—whether it's waiting, distilling, or swapping—that can effectively maximize throughput. We compare the switch's performance under the optimal distillation-enabled policy with that excluding distillation.
Simulations of the two policies demonstrate the improvements that are possible in principle via optimal use of distillation with respect to average throughput, average fidelity, and jitter of end-to-end entanglement, as functions of fidelity threshold. Our model thus helps capture the role of entanglement distillation in mitigating the effects of decoherence in a quantum switch in an entanglement distribution network, adding to the growing literature on quantum switches. We also compare the switch’s performance found using simulations with theoretical bounds found out by employing queuing theory concepts on the same model
Audit and Evaluation of Medication Overrides at a Tertiary Care Center
No full textPurpose: Medication overrides allow removal of a medication from an automated dispensing cabinet (ADC) before a pharmacist reviews the order in an emergent situation. Administration of medications prior to a medication order and pharmacist review increases the risk for medications errors. Unsafe medication practices and medication errors are the leading cause of avoidable harm to patients and represents a major public health issue. The public health significance of this project was to audit medication override practices at Allegheny General Hospital (AGH) to ensure safe medication practices.
Method: A randomly selected day in 2022 was audited. Override information was collected retrospectively from ADC data and matched to a patient using the electronic health record. The primary outcome of the study was to measure AGH’s compliance to the Medication Override Policy. Override compliance was defined as timely administration (within one hour), linkage to a medication order, and timely link (within one hour). The secondary outcome of this study was to evaluate if changes should be made to the current medication override list.
Results: On the randomly selected day, there were a total of 95 overrides. There was 98.6% compliance in timely administration, 87.5% compliance in linking or medications, and 98.3% compliance in timely linking of medications. Overall compliance was 84%. The AGH medication override list contained 269 medications. 93 medications were recommended for removal from the override list
Viral Hepatitis Services in Pennsylvania Jails: Assets, Barriers, and Opportunities
No full textViral hepatitis is an infectious disease leading to liver inflammation and damage. While advancements have been made in controlling the spread of viral hepatitis worldwide, it remains a prevalent public health issue. Many populations face disparities regarding viral hepatitis, especially incarcerated populations. Due to these individuals’ unique vulnerabilities, carceral system settings may be a vital source of viral hepatitis care for these individuals. As such, the Pennsylvania Department of Health conducted a survey investigating the status of viral hepatitis services for incarcerated individuals in county jails. The survey assessed viral hepatitis A, B, and C testing, treatment, and vaccination practices among all county jails throughout Pennsylvania (N=53). The majority of jails provided hepatitis C (90%) but not hepatitis B (21%) on-site testing services. Most jails provided hepatitis C (79%) and B (81%) on-site treatment services in some capacity. Finally, the majority jails provided on-site hepatitis B vaccination (81%) but not hepatitis A vaccination (17%). These findings show possible opportunities for service expansion in jails while possibly informing policy interventions improving the health of incarcerated populations. This is of major public health significance due to incarcerated populations’ high risk for infection as well as their cycle of incarceration and release back into the community
Accuracy of Statistical Inferences Drawn from Two-Sample Graphs
No full textWhat sorts of graphical formats best convey effect size and degree of certainty of a find- ing? Confidence intervals are commonly used to show uncertainty, yet lay people and experts fail to correctly interpret their meaning. There has been a recent push to present individual data points rather than only presenting aggregated summary statistics (e.g., means, confi- dence intervals, lines of best fit). But it is unclear how well people can aggregate raw data presented in a graphical format. Across two studies, we presented participants with hypo- thetical study outcomes of two independent groups in three graph styles: dot plots, mean with 95% confidence interval (CI) plots, combined plots, and bee plots. We asked partici- pants to make judgments about the effect size, using the Common Language Effect Size, or Bayes Factors. Participants were more likely to underestimate effect sizes and Bayes Factors for dot plots and bee plots compared to mean + 95% CI plots and combined plots. These findings suggest that people have trouble making statistical inferences when presented with raw data points in graphs