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Title: Improving Niobium Superconducting Radio-Frequency Cavities by Studying Tantalum
Creator: Helfrich, Halle
Date: 2023
Description: Niobium superconducting radio-frequency (SRF) cavities are widely used accelerating structures. Improvements in both quality factor, Q0, and...
Show moreNiobium superconducting radio-frequency (SRF) cavities are widely used accelerating structures. Improvements in both quality factor, Q0, and maximum accelerating gradient, Eacc, have been made to SRF cavities by introducing new processing techniques. These breakthroughs include processes such as nitrogen doping(N-Doping) and infusion, electrochemical polishing (EP) and High Pressure Rinsing (HPR). [1] There is still abundant opportunity to improve the cavities or, rather, the material they’re primarily composed of: niobium. A focus here is the role the native oxide of Nb plays in SRF cavity performance. The values of interest in a given cavity are its quality factor Q0, maximum accelerating gradient Eacc and surface resistance Rs . This work characterizes Nb and Ta foils prepared under identical conditions using X-ray photoelectron spectroscopy (XPS) to compare surface oxides and better understand RF loss mechanisms in Nb SRF cavities and qubits. It is well established that Ta qubits experience much longer coherence times than Nb qubits, which is probably due to the larger RF losses in Nb oxide. By studying Tantalum, an element similar to Niobium, the mechanisms of the losses that originate in the oxide and suboxide layers present on the surface of Nb cavities might finally be unlocked. We find noticeable differences in the oxides of Nb and Ta formed by air exposure of clean foils. In particular, Ta does not display the TaO2 suboxide in XPS, while Nb commonly shows NbO2. This suggests that suboxides are an additional contributor of RF losses. We also suggest that thin Ta film coatings of Nb SRF cavities may be a way of increasing Q0. It is in the interest of the accelerator community to fully understand the surface impurities present in Nb SRF cavities so that strategies for mitigating the effects can be proposed.
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Title: Evaluation of the efficacy of power ultrasound technology coupled with organic acids to reduce listeria monocytogenes on peaches and apples
Creator: Joshi, Mayura Anand
Date: 2024
Description: Fresh fruits and vegetables are prone to microbial contamination throughout different phases of human handling, processing, transportation,...
Show moreFresh fruits and vegetables are prone to microbial contamination throughout different phases of human handling, processing, transportation, and distribution. Emerging technologies, such as power ultrasound, have received attention due to their capacity to reduce or eliminate foodborne bacterial pathogens on these commodities. Power ultrasound, when combined with certain antimicrobials, has demonstrated its effectiveness as a valuable tool for washing fresh produce. The objective of this study was to examine the effectiveness of power ultrasound combined with organic acids on the reduction of Listeria monocytogenes on fruits. In this study, peaches and apples were subjected to surface inoculation with a four-strain cocktail of L. monocytogenes and dried for 1 h. Stomacher bags, containing 225 mL of citric, lactic, or malic acids at concentrations of 1%, 2%, or 5%, were employed for treating inoculated peaches and apples. The acid treatment was used alone, or in combination with power ultrasound for 2, 5, or 10 min. Water was used for controls. Before treatment, the initial population of L. monocytogenes on apples was lower compared to the initial population on peaches, with apples showing a 1.94 log CFU/fruit reduction. Water controls demonstrated no significant log reduction in both apples and peaches. The greatest L. monocytogenes reduction on apples occurred when treated with 1% citric acid for 2 min with power ultrasound where L. monocytogenes was significantly reduced from 6.98±0.88 log CFU/fruit to 5.56±0.91 log CFU/fruit. The greatest L. monocytogenes reduction on peaches occurred when treated with 5% citric acid for 5 min with power ultrasound where L. monocytogenes was significantly reduced from 7.44±0.45 log CFU/fruit to 6.68±0.40 log CFU/fruit. Overall, the combined effect of acid and power ultrasound was more pronounced in apples than in peaches. The survival of L. monocytogenes on apples and peaches appeared to be highly dependent on the specific treatment and hurdle technology applied. The combination of ultrasound hurdle technology with acid washing has proven effective in reducing L. monocytogenes on both peaches and apples, with a more significant impact observed on apples. While acid washing is a more economical option compared to ultrasound technology, the efficiency of microorganism reduction is considerably enhanced when power ultrasound is combined with organic acids. Looking ahead, the development of cost-effective power ultrasound methods could facilitate widespread adoption of ultrasound hurdle technology in the produce industry.
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Title: Characterization of Novel Concrete Formulations: High-Volume Fly Ash for Precast Industry Use and Non-Proprietary UHPC
Creator: Ordillas, Kurt Andrew
Date: 2024
Description: The use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due...
Show moreThe use of high-volume fly ash concretes can be challenging for high-early strength applications, such as in precast construction, largely due to potential delays in strength gain resulting from relatively lower heats of hydration of the underlying binder formulations. Considering that the use of higher levels of available fresh or landfilled fly ash as a replacement for traditional ordinary Portland cement (OPC) could result in more sustainable mix designs, a framework to develop novel, high-volume fly ash mixes with optimized dosages of commercial grade gypsum and accelerating admixtures to enhance early-age strength performance. Early-age mechanical properties such as compressive strength, modulus of rupture, and modulus of elasticity were evaluated starting within 24 hours of specimen preparation. Experimental test results were then characterized and subsequently analyzed relative to current design provisions to highlight the best performing trial mixes (with respect to the early-age strength target) and cases where current design provisions are either unconservative or overly-conservative with respect to the test data. Additionally, thermal properties of concrete produced with fly ash were tested with two different curing environments, along with using code equations to determine if high volume fly ash provides a higher thermal resistance compared to OPC concrete. Wrapping up cementitious replacement with non-proprietary ultra high-performance concrete (UHPC) for transportation structures. Then reproducing mixtures to ensure target compressive strength values could be reached. Followed by increasing batch size to a larger quantity using a large mixer to create full-size specimens.
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Title: Ink drawing, 1975
Date: 1975-07-07
Description: Untitled drawing by Mary Henry, accompanied by mathematical calculations.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Pencil Drawing on Tissue, undated
Description: Untitled pencil drawing on tissue paper by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink and Colored Pencil Drawings, undated
Description: Untitled drawings by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink and pencil sketches, undated
Description: Untitled ink and pencil sketches by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink and Colored Pencil Drawings, undated
Description: Untitled drawings by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Pencil Drawing on Tissue, undated
Description: Untitled pencil drawing on tissue paper by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink Drawings, undated
Description: Untitled drawings by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Colored Pencil Drawings, undated
Description: Untitled colored pencil drawings by Mary Henry, date unknown. Inscription on verso: "William Winter Comments, PO Box 817, Sausalito"
Collection: Mary Dill Henry Papers, 1913-2021

Title: Colored Pencil Drawings, undated
Description: Untitled colored pencil drawings by Mary Henry, date unknown. Inscription on verso: "William Winter Comments, PO Box 817, Sausalito"
Collection: Mary Dill Henry Papers, 1913-2021

Title: Colored pencil drawing, undated
Description: Untitled colored pencil drawing by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Pencil drawing, undated
Description: Untitled drawing by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink drawing, undated
Description: Untitled drawing by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Ink drawing, undated
Description: Untitled drawing by Mary Henry, date unknown.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Pencil drawings, 1977
Date: 1977
Description: Untitled drawings by Mary Henry, accompanied by mathematical calculations.
Collection: Mary Dill Henry Papers, 1913-2021

Title: Testing actor and partner mediation effects of the mindfulness-relationship satisfaction association in long-distance relationships
Creator: Manser, Kelly A.
Date: 2023
Description: Long-distance romantic relationships (LDR) have become increasingly common as technology and sociocultural norms have evolved. Individuals in...
Show moreLong-distance romantic relationships (LDR) have become increasingly common as technology and sociocultural norms have evolved. Individuals in LDR, many of whom are post-secondary students, report LDR-specific experiences and stressors. Nonetheless, romantic relationship satisfaction (RS) nonetheless appears comparable between LDR and non-LDR relationships, although the underlying mechanisms are not well-understood. Mindfulness, which relates positively to RS and negatively to stress, is minimally studied in LDR. Moreover, despite empirical and theoretical support, few studies have tested stress as a mediator of associations between mindfulness and RS at the within-person level (termed actor effects) or between-person level (partner effects). This study tested a theoretically-grounded, empirically-supported Actor-Partner Interdependence Mediation Model (APIMeM) in a sample (N = 150; 75 dyads) of post-secondary students and their LDR romantic partners. As hypothesized, an partner-actor indirect effect emerged of T1 actor mindfulness on T2 partner RS through decreased T2 partner stress. Unexpectedly, no direct, total, or indirect effects of T1 actor mindfulness on T2 actor stress or T2 actor RS emerged. Findings suggest that within- and between-person associations between mindfulness, stress, and RS may present uniquely in LDR, with implications for research, clinical practice, and policy.
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Title: Associations between subjective cognitive decline, neurodegeneration, and vascular neuroimaging markers: Findings from a multiethnic cohort
Creator: Gonzalez, Christopher
Date: 2023
Description: Mounting evidence suggests that subjective cognitive decline (SCD) may provide a unique target to identify the earliest changes in cognitive...
Show moreMounting evidence suggests that subjective cognitive decline (SCD) may provide a unique target to identify the earliest changes in cognitive function in Alzheimer’s disease (AD). In addition, vascular-related risk factors are also linked to increase the risk of clinical expression of AD, and independently increase the risk for vascular dementia (VaD). However, most investigations have not explored SCD across a multiethnic population. The study investigated 1) the associations between white matter hyperintensities (WMH) and targeted neuroimaging AD markers (hippocampal volume, cortical thickness of AD regions) with SCD amongst a multiethnic cohort, and 2) whether race moderated the relationship between them. A total of 871 older adults ages from 62-96 years old with a mean age of 74.48 (SD = 6.11), mean education of 12.79 years (SD = 4.53), and with 62% identifying as female were recruited from preexisting data from the Washington Heights Inwood Columbia Aging Project (WHICAP). Linear regression model revealed a significant association between WMH and both AD targeted neuroimaging markers across the total sample. Secondary analyses revealed that race did not moderate the relationship between WMH and AD cortical thickness with SCD but did in fact moderate the relationship between hippocampal volume and SCD. Results suggest that cultural biological differences exist in the Hispanic/Latine individuals compared to non-Hispanic White and non-Hispanic Black individuals.
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Title: Design for Equivalence: Mutual Learning and Participant Gains in Participatory Design Processes
Creator: Geppert, Amanda Anne
Date: 2023
Description: The ways in which people are or are not—aware, eligible, able, invited, required, supported, willing, and/or forced, among other conditions—to...
Show moreThe ways in which people are or are not—aware, eligible, able, invited, required, supported, willing, and/or forced, among other conditions—to participate in the procedures or experiences that constitute world-making activities—from voting, policymaking, or designing algorithms, technologies, products, programs, services, interventions, infrastructures, or systems, among other things—that affect their lives—is a central issue of our time. It demands careful consideration and is of great consequence as to whether or not the worlds we create are equitable, sustainable, and just, so that all people have free and equal standing and a real opportunity to belong and flourish. This study took up this issue in the context of participatory design practice and research and the making of sexual and reproductive health interventions with and for adolescents who are marginalized by race, class, ethnicity, gender, and sexuality, in Lucknow, Uttar Pradesh, India, and Chicago, Illinois, United States. The study advances knowledge in design by exploring how problem-focused, front-end participatory design processes expand or constrain the epistemic authority of less powerful actors, more specifically, systematically excluded individuals and groups. The study was conducted in two parallel phases. First, through a theoretical elaboration and critical analysis, it examined the application of Mouffean agonism in recent formulations of participatory design processes to address complex social and political issues with marginalized individuals and groups. The analysis demonstrated that a key construct—the chain of equivalence—is absent and resulted in the failure of these processes to achieve the collective, counter-hegemonic, and emancipatory responses strong enough to counter power as imagined by Chantal Mouffe. Second, an explanatory embedded multiple case study was conducted on two front-end participatory design workshops to understand what less powerful actors gain by engaging in collaborative processes of design and how practices and processes do or do not support their epistemic authority and matters of care. Thematic analysis suggested how the practices of collective information sharing and gathering—mutual learning and learning— affect participant gains and design process outputs. Additionally, thematic analysis informed a theoretical, conceptual, and practical move to expand beyond the original scope of the Mouffean chain of equivalence to include collaborating actors who may not be equivalently disadvantaged by current power relations, but who are committed to participatory design processes that prioritize the issues and matters of care of less powerful actors. When considered together, findings from both research phases inform the development of design for equivalence, at once a theoretical stance and a methodological framework to inform the selection of approaches, theories, processes, methods, practices, and tools for participatory design processes that support the epistemic authority of participants in challenging social and structural inequalities and creating articulations of the common good strong enough to counter dominant paradigms.
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