UA Faculty Research: Recent submissions
Now showing items 1-20 of 20680
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Pivotal role of transition density in circularly polarized luminescenceRealizing high luminescence dissymmetry factor (g) in circularly polarized luminescence (CPL) materials remains a big challenge, which necessitates understanding systematically how their molecular structure controls the CPL. Here we investigate representative organic chiral emitters with different transition density distributions and reveal the pivotal role of transition density in CPL. We rationalize that to obtain large g-factors, two conditions should be simultaneously satisfied: (i) the transition density for the S1 (or T1)-to-S0 emission must be delocalized over the entire chromophore; and (ii) the chromophore inter-segment twisting must be restricted and tuned to an optimal value (∼50°). Our findings offer molecular-level insights into the CPL of organic emitters, with potential applications in the design of chiroptical materials and systems with strong CPL effects.
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Transgressions and regressions in stratigraphic view: Facies of Holocene sediments of the Tuckerton Marshes, New Jersey (2nd edition)The Tuckerton salt marshes of the central New Jersey coast are the current depositional surface overlying Holocene marginal marine deposits that were investigated by hand coring and augering to depths as great as 10.6 m. An erosional surface on Sangamon marine topography underlies Holocene marsh, lagoon, and tidal delta sediments. Holocene facies geometry indicates a transgression followed by an episode of marine erosion and a depositional regression. Facies are mapped in terms of grain size, macro-fauna, Foraminifera, plant remains, and sedimentary structures. Some of the more interesting results of this investigation are: 1) typical depositional regression sequences occur even where late-Holocene sea-level rise continued along this coast, 2) coherent facies assemblages representing deeper/more saline conditions form the interior of a transgressive-regressive wedge in the landward part of the study area, 3) transgressional sequences are sporadically preserved in seaward parts due to superposed high-energy environments, producing an asymmetric transgression- regression distribution there, and 4) tidal-channel migration can form volumetrically dominant sand bodies in the sequence.
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Anomalous textures in porphyritic granite of Andhra Pradesh (India)Apparently perthitic textures of microcline phenocrysts in this rock are not due to exsolution but to deformation. Microscopic fracture planes show no offset, however, and are restricted to feldspar crystals, i.e. absent in quartz. A hypothesis of depth formation is presented, and possible shock origin discussed.
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Architecture of ponderosa pine bark in relation to spalling behaviorShedding/spalling behavior of ponderosa bark, with or without fire impetus, is primarily a function of the geometry of individual bark pieces, which are stable laterally due to their digitate shapes, and metastable radially due to flanges around the base of each piece. In detail, each piece is a zoned envelope of distinctive elements, separated from other pieces by another element. Different physical properties of these elements are probably involved in bark-piece expulsion, which requires sequential flange release. Criteria to determine any role of fire in bark-piece expulsion are described.
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Shakeup--cultural impacts of tectonic activity in ancient complex culturesMy purpose in mounting this entry in bepress is to make public the text and illustrations of two talks I have recently given on this subject, related in turn to my 2015 book with Lexington Press "Impact of tectonic activity on ancient civilizations."
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Anomalous upland gravel unit in Pecos area of northern New MexicoAn extensive cobble-boulder gravel in the area of Pecos and its National Historical Park is anomalous both in its depositional geometry and its clast population, the latter dominated by metasedimentary muscovite gneiss and quartzite. Derivation is from high-grade metamorphic units of the northernmost Pecos River headwaters that form a very small fraction of the drainage. A short-lived transport system is consistent with the depositional geometry of the gravel, which is draped over a large area, apparently as an outwash fan now stranded by later downcutting of the Pecos River. Episodic outflow due to glacial or post-glacial mass-wasting is suggested by the geomorphology of the headwater area among the Truchas Peaks.
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Internal variations and structure of the Catalina Intrusive Suite, Tucson area, Arizona--a reconnaissance and guide to needed work -- Sketches in Arizona GeologyThe Catalina Intrusive Suite (”Catalina Granite”), forming the western end of the Santa Catalina Mountains north of Tucson, is apparently of mid-Tertiary age and post-dates the mylonitic deformation of older granites of the range. Its semicircular outcrop shape is bisected by the Pirate fault, though outliers are present in the Tortolita Mountains. This shape and the presence of ring-dikes previously suggested concentric structure of otherwise homogeneous elements. This study however divides the Catalina IC into two units, the older of which itself shows two domain.. The basal domain of the older unit , mostly of porphyritic coarse granite, contains two bands of problematic mafic segregations and dikes which suggests successive intrusions of granite and mafics. The upper domain of the older unit , mostly of quartz monzonite, shows gravity layering that dips NNE, like most of the Catalina IS’s country rocks. The younger unit , of finer-grained leucocratic granite with a distinct xenolith assemblage, forms a nearly-continuous rim around the older unit. This rim may be considered a three-dimensional carapace if some internal outcrops are part of a “lid”. This rim/carapace is present only as sporadic thin rim-dikes on the north, but thick on the east (the Reef of Rock ring-dike) and south. That is, the Catalina IS is hinged on its northern margin. The external shape of the Catalina IS as a whole is insufficiently constrained in three dimensions from its outcrop pattern, despite excellent exposure with considerable topographic relief. One possibility is a NNE- tilted “bandshell”-shape (open to the Pirate fault), and if so the thick southern rim of younger leucogranite probably intruded a subsided southern margin of the older unit, in “trap-door” manner. Despite excellent work now about 50 years old, recent work had lagged until Ducea et al. (2020), and many features of the Catalina IS are still insufficiently known and deserve attention. Among these are the age of the younger unit, and the rotation history of the older unit.
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Geomorphic evolution of the ancient site of Los Millares, Andalucia (Spain) –mid-Holocene sedimentation, eustacy, and tectonic activityThe material remains of the Copper-Age (ca. 5200-4200 BP) site of Los Millares (Almeria province), currently 19 km inland from the Mediterranean, suggest marine connections. It is architecturally complex, and its clifftop setting above the aggrading Andarax River suggests defensibility. Its mid-Holocene age suggests the possibility of formerly extensive estuarine environments (net tectonic base-level control being locally minor despite regional tectonic activity), thus giving the site unusual trade potential. In spite of substantial subsurface data, geomorphic reconstruction becomes ambiguous past known medieval estuarine morphology due to the difficulty of acquiring datable material from depth. Certainly Los Millares when occupied had much closer access to marine waters than at present, and protecting cliffs were more formidable. Our conclusions suggest that additional investigations of several types are warranted.
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A compendium of glacigenic features of the Truchas Peaks area of northern New Mexico, informed by LiDAR and other remote methodsFeatures of the cirques and contiguous valleys of the Truchas Peaks area show anomalous features in remote images, many of which do not fit a conventional valley-glacial model. Indeed some cirque lakes of the area are impounded not by moraines but by mass movements of various sorts, which probably result from previous glaciation. The combination of LiDAR and Google Earth is powerful in describing these features, the former for dynamic description and the latter for detailed vertical control. In this report I describe twenty cirque/valley combinations, hoping to elecit interest in field description of pertinent features.
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Identification of key factors and mechanism determining arsenic mobilization in paddy soil-porewater-rice systemArsenic (As) mobilization in paddy fields poses significant health risks, necessitating a thorough understanding of the controlling factors and mechanisms to safeguard human health. We conducted a comprehensive investigation of the soil-porewater-rice system throughout the rice life cycle, focusing on monitoring arsenic distribution and porewater characteristics in typical paddy field plots. Soil pH ranged from 4.79 to 7.98, while porewater pH was weakly alkaline, varying from 7.2 to 7.47. Total arsenic content in paddy soils ranged from 6.8 to 17.2 mg/kg, with arsenic concentrations in porewater during rice growth ranging from 2.97 to 14.85 μg/L. Specifically, arsenite concentrations in porewater ranged from 0.48 to 7.91 μg/L, and arsenate concentrations ranged from 0.73 to 5.83 μg/L. Through principal component analysis (PCA) and analysis of redox factors, we identified that arsenic concentration in porewater is predominantly influenced by the interplay of reduction and desorption processes, contributing 43.5 % collectively. Specifically, the reductive dissolution of iron oxides associated with organic carbon accounted for 23.3 % of arsenic concentration dynamics in porewater. Additionally, arsenic release from the soil followed a sequence starting with nitrate reduction, followed by ferric ion reduction, and subsequently sulfate reduction. Our findings provide valuable insights into the mechanisms governing arsenic mobilization within the paddy soil-porewater-rice system. These insights could inform strategies for irrigation management aimed at mitigating arsenic toxicity and associated health risks.
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In vivo safety and pulmonary vein isolation performance of a new cryoballoon for the treatment of atrial fibrillationBackground: Cryoablation to achieve pulmonary vein (PV) isolation has become one of the standard approaches for atrial fibrillation (AF) ablation. The Arctic Front series cryoballoon and Achieve circular mapping catheter (Medtronic) inherently possess design defects that have been associated with unfavorite clinical outcomes. Lately, a new cryoablation system (Nordica Cryoablation System, Synaptic Medical) was developed with improved design of the cryoballoon and circular mapping catheter to address the inadequacies of current cryoablation technology. An animal study was conducted to test the efficacy and safety in performing PVI with the Nordica Cryoablation System. Methods: Pulmonary vein isolation with the Nordica Cryoablation System was performed on 12 PVs of six healthy canines. Acute PVI and peri-procedural complications were recorded. All animals underwent a repeat EP study at least 4 weeks after index procedures followed by pathological and histological assessments of the heart and collateral/downstream organs after planned euthanasia. Results: Acute PV isolation was achieved in all targeted PVs with 50% of PVs being isolated with a single cryoablation application. There were no major peri-procedural complications or device malfunction events. All PVs remained isolated after 29–30 days follow-up. Histological examination showed transmural cryo-lesions at treated sites with minimal inflammation, neovascularization, and neointima formation but no significant injury to adjacent tissue or embolization in downstream organs. Conclusion: Acute and durable PVI can be achieved by using the novel Nordica Cryoablation System. Ablation with this new cryoablation system is associated with transmural lesions at targeted myocardium but creates no injury to the collateral tissues or downstream organs.
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Demonstrating Inclusion and Allyship: Amplifying an Indigenous Voice Through Physical and Digital ExhibitionIn this chapter, I discuss how I displayed resources to help promote the knowledge that the Navajo people have “always had the rule of law” and to amplify the Navajo writer, Joseph K. Austin, behind that knowledge.3 To support and demonstrate the need for further inclusion, I provide a literature review of scholarship and detail the genesis of the physical and digital exhibits I curated from the works cited by Austin in his article, “The Words of the Talking God: Building and Sustaining Native Nations Through the Common Law.” I describe my collaboration with Austin and other colleagues from my law library and discuss how future collaboration is sustainable.
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Shifting Gears: A case study of bicycle planning and decision-making in Tucson, ArizonaPlanners face a complex process from planning projects to final construction and evaluation in cycle planning. Planners tend to coordinate with peers in neighboring cities, advocates, politicians, other policymakers, and researchers to implement cycling plans. Documenting this decision-making process and the sources of information that guide decisions can provide insight into creating better cycling planning research and fostering stronger collaborations. We first provide a brief history of cycle planning in Tucson, Arizona, to demonstrate the current issues and efforts. Then, we present findings from interviews with Tucson planners and an advocate to explore information sources, collaboration, barriers, and opportunities for action for bicycle planning. Our results highlight the need for research presented in consumable ways, particularly through professional networks, and the potential for university outreach offices to assist in public participation and outreach, professional education, and collaboration on data collection and analysis on cycling projects. Focusing on these avenues can strengthen the science to decision-making pipeline. These lessons can also help improve bicycle planning in other communities.
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Investigating Volumetric Video Creation and Curation for the Digital Humanities: a White Paper Describing Findings from the Project: Preserving BIPOC Expatriates’ Memories During Wartime and BeyondVolumetric video capture technologies offer humanities scholars and other researchers new, immersive ways of engaging with historical and cultural knowledge for research and pedagogical purposes; however, the high cost of this technology and a paucity of expert knowledge in the field have limited its adoption. In particular, volumetric video offers rich new possibilities for recording, preserving, and re-experiencing BIPOC (Black, indigenous, and other people of color) stories in immersive detail, which have been underrepresented in the historical record. This technology is still experimental and is typically limited to specialized labs at large research universities. To democratize the technology and ensure that the potential benefits of this new technology can be realized by digital humanities scholars more broadly, a group of researchers at the University of Arizona and Williams College, in collaboration with technical innovators from the world-renowned volumetric capture studio, VoluCap, GmbH, embarked on a project to explore the challenges and potential benefits of volumetric video capture for BIPOC storytelling. The team traveled to Berlin/Potsdam in June 2023 to visit VoluCap Studios and record several volumetric capture videos, including a video of Mike Russell, who told a story about his father’s experiences as an African-American servicemember during World War II. Recording these videos and observing their processing pipeline allowed us to consider the logistical and data curation challenges of this format. Dr. Bryan Carter, lead-PI on the project, is also director of UArizona’s Center for Digital Humanities, which houses a prosumer-level volumetric capture studio. Comparing the workflows at the Center for DH with what was observed at VoluCap allowed the project team to better understand the challenges and benefits of volumetric capture at different scales and levels of quality. Because volumetric videos are expensive and time consuming to create, an important objective of this project was to examine the preservation and curation challenges associated with the digital objects created through the volumetric capture process. Planning for preservation, access, and reuse of volumetric video assets is essential to realizing their full value. This report describes the creation challenges and pedagogical benefits of volumetric video, as well as preservation and curation challenges.
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Efficient System-Level Design Space Exploration for High-Level Synthesis Using Pareto-Optimal Subspace PruningHigh-level synthesis (HLS) is a rapidly evolving and popular approach to designing, synthesizing, and optimizing embedded systems. Many HLS methodologies utilize design space exploration (DSE) at the post-synthesis stage to find Pareto-optimal hardware implementations for individual components. However, the design space for the system-level Pareto-optimal configurations is orders of magnitude larger than component-level design space, making existing approaches insufficient for system-level DSE. This paper presents Pruned Genetic Design Space Exploration (PG-DSE)-an approach to post-synthesis DSE that involves a pruning method to effectively reduce the system-level design space and an elitist genetic algorithm to accurately find the system-level Pareto-optimal configurations. We evaluate PG-DSE using an autonomous driving application subsystem (ADAS) and three synthetic systems with extremely large design spaces. Experimental results show that PG-DSE can reduce the design space by several orders of magnitude compared to prior work while achieving higher quality results (an average improvement of 58.1x). © 2023 Copyright held by the owner/author(s).
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Cross-Modality Continuous User Authentication and Device Pairing With Respiratory PatternsAt-home screening systems for obstructive sleep apnea (OSA) can bring convenience to remote chronic disease management. However, the unsupervised home environment is subject to spoofing and unintentional interference from the household member. To improve robustness, this work presents SIENNA, an insider-resistant breathing-based authentication/pairing protocol. SIENNA leverages the uniqueness of breathing patterns to automatically and continuously authenticate a user and pairs a mobile OSA app and a physiological monitoring radar system (PRMS). SIENNA does not require biometric enrollment and instead transforms the respiratory measurements taken during the user's routine physical checkup into breathing biometrics comparable with the PRMS readings. Furthermore, it can operate within a noisy multitarget home environment and is secure against a co-located attacker through the usage of joint approximate diagonalization of eignematric-independent component analysis, fuzzy commitment, and friendly jamming. We fully implemented SIENNA and evaluated its performance with medium-scale trials. Results show that SIENNA can achieve reliable (>90% success rate) user authentication and secure device pairing in a noisy environment against an attacker with full knowledge of the authorized user's breathing biometrics. © 2014 IEEE.
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Influence of personal and collective social capital on flood preparedness and community resilience: Evidence from Old Fadama, GhanaSocial capital constitutes an important resource in vulnerable cities of the developing world where formal disaster management capacities are weak, responses are limited, and socio-economic deprivations run deep along spatial dimensions. Yet, little is known about how the different types of social capital contribute to flood preparedness and better community resilience, particularly in informal settlement settings. Drawing on a survey of 391 respondents in Old Fadama, an informal settlement in Ghana, and using structural equation modelling, we found that personal and collective social capitals are significant predictors of flood preparedness and community resilience. However, collective social capital has a stronger predictive ability than personal social capital. Also, flood preparedness mediated the relationship between personal and collective social capital and community resilience. This makes it imperative for disaster managers and policymakers to recognise and work within the existing individual and collective networks, which has the potential to activate “soft” capital accumulation necessary to transition communities from vulnerability to resilience. © 2023 The Authors