21978 research outputs found
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North American Newspaper Coverage of Climate Change or Global Warming, 2000-2025 - October 2025
No full textThe Media and Climate Change Observatory Data monitors 131 sources (across newspapers, radio and TV) in 59 countries in seven different regions around the world. Data is assembled by accessing archives through the Lexis Nexis, Proquest and Factiva databases via the University of Colorado libraries. More information may be found at: http://mecco.colorado.edu.</p
Middle Eastern Newspaper Coverage of Climate Change or Global Warming, 2004-2025 - October 2025
No full textThe Media and Climate Change Observatory Data monitors 131 sources (across newspapers, radio and TV) in 59 countries in seven different regions around the world. Data is assembled by accessing archives through the Lexis Nexis, Proquest and Factiva databases via the University of Colorado libraries. More information may be found at: http://mecco.colorado.edu.</p
Russian Newspaper Coverage of Climate Change or Global Warming, 2000-2025 - October 2025
No full textThe Media and Climate Change Observatory Data monitors 131 sources (across newspapers, radio and TV) in 59 countries in seven different regions around the world. Data is assembled by accessing archives through the Lexis Nexis, Proquest and Factiva databases via the University of Colorado libraries. More information may be found at: http://mecco.colorado.edu.</p
Potential Airborne Transmission of SARS-CoV-2 Through Bathroom Ventilation Ducts Associated with an Outbreak in a Residential Building in Santander, Spain, 2020
Get PDFDuring the COVID-19 pandemic, airborne transmission of SARS-CoV-2 via respiratory aerosols was acritical concern in indoor environments. In the city of Santander, Spain, an outbreak in a multi-familyresidential building during a period of low community transmission revealed vertical clustering of 15cases in four homes. The building’s design included single interior bathrooms without windows in eachhome, ventilated by a shared vertical bathroom duct system. Field measurements, computational fluiddynamics (CFD) simulations, and multi-zone airflow modeling were performed to evaluate verticaldisease transmission potential in the Santander building. Epidemiological and genetic data combinedwith the field-collected data and modeling indicated that the most plausible transmission route was thebathroom vertical ventilation duct system, which facilitated movement of infectious aerosol betweenvertically connected homes. Recommendations for mitigating future risks include the installation offorced air exhaust fans with non-return flaps in bathroom ducts.</p
Generalizing Low-Resource Morphology: Cognitive and Neural Perspectives on Inflection
Get PDFState of the art NLP methods to leverage enormous amounts of digital text are transforming the experience of working with computers and accessing the internet for many people. However, for most of the world’s languages, there is insufficient digital data to make recently popular technology like large language models (LLMs) possible. New technology like LLMs are typically not well-suited for underrepresented languages—often referred to as low-resource languages in NLP—without sufficient digital data. In this case, simpler language technologies like dictionaries, morphological analyzers, and text normalizers are useful. This is especially apparent for language documentary life-cycles, building educational tools, and the development of language typology databases. With this in mind, we propose techniques for automatically expanding coverage of morphological databases and develop methods for building morphological tools for the large set of languages with few available resources. We then study the generation capabilities of neural network models that learn from these resources. Finally we propose methods for training neural networks when only small amounts of data are available, taking inspiration from the recent successes of self-supervised pretraining in high-resource NLP.</p
History in Ruins: Dana Kavelina's Letter to a Turtledove
Get PDFThis paper explores Dana Kavelina’s 2020 experimental essay film Letter to a Turtledove, which speaks out against linear historical narratives of Donbas. Kavelina uses dialectical montage techniques – accumulation, juxtaposition, and contrast – to overlay Ukraine’s Soviet history with its turbulent present. Kavelina treats Ukraine’s Soviet past and post-Maidan present not as mutually exclusive, but as coexisting and intertwined historical temporalities. Letter to a Turtledove uses a nonlinear narrative to describe the isolation of Donbas, a region that became politically and culturally cut-off from the rest of Ukraine following the start of war in 2014 and the passing of the decommunization laws in 2015. The film presents Donbas as a liminal space dominated by the ghosts of the past. Kavelina also engages with the physical and cultural ruins left from Soviet society that were left abandoned when Ukraine transitioned to capitalism in the early 1990s. She calls us to listen to both the living and the dead of the region, employing Dziga Vertov’s techniques of sound montage from Enthusiasm: The Symphony of Donbas (1931). Simultaneously, she is in conversation with several anti-capitalist and antimilitant artistic movements, namely the German Expressionists of the interwar period and the Kharkiv School of Photography. Through an eclectic and fast-paced montage, Kavelina reveals how Donbas has become a region trapped in cycles of exploitation, displacement, and violence. However, she resists this cycle, using art as a space for envisioning utopia and redemption. Drawing on the theories of Walter Benjamin and nineteenth-century Russian Cosmists, Kavelina works to remember all of Donbas’ dead equally, returning agency to the silenced.</p
Interlimb Differences in Cartilage Strain and Relaxometry 6- and 12-Months Post-ACL Reconstruction: A Pre-Osteoarthritis Biomarker
Get PDFAnterior cruciate ligament (ACL) injuries cause deterioration of knee cartilage which can lead to osteoarthritis (OA). OA currently has no diagnostic methods to detect the early stages of disease. This study used non-invasive methods to detect changes in knee cartilage 6- and 12-months post ACL reconstruction surgery on both legs of a cohort of patients. Strain, displacement, and T1⍴ relaxation time were quantified using a combination of magnetic resonance imaging (MRI) sequences on the reconstructed knee and the uninjured contralateral knee. A linear mixed effects model was used to determine metrics capable of identifying subtle changes in cartilage over time and between legs of the patients. We found displacement in the X direction to be lower in the reconstructed limb than the contralateral limb. Displacement in Y was higher in the ACLR limb compared to the contralateral limb and decreased from 6- to 12-months. We found femoral shear strain to be higher in the ACLR limb. Tibial shear strain was higher at 6-months compared to 12-months. Tibial axial strain was lower in the ACLR leg compared to the contralateral leg. T1⍴ relaxation times were found to decrease from 6- to 12-months. At the 6-month time point the ACLR leg relaxation time was lower than the contralateral leg, but at 12-months we found the ACLR leg had greater relaxation times. This work demonstrates the potential for strain, displacement, and T1⍴ to be biomarkers for detecting early OA as they can pinpoint changes in cartilage health before symptom onset and damage is irreversible.</p
Leveraging Nanomaterials for Measurements at the Quantum Limit
Get PDFThis dissertation reports on sensing enhancements enabled by nanomaterials, focusing on twoareas: magnetic field sensing and imaging, and fluorescence microscopy. In both domains, we find that nanomaterials lead to sensors which outperform bulk and microscale materials.
Motivating the magnetic field sensing project, we observed that most existing magnetic field sensing techniques follow a trend where their magnetic field sensitivity is inversely proportional to sensor volume. This presents a challenge when attempting to perform high-sensitivity, spatially resolved magnetic field measurements.
The primary research question investigates whether this paradigm could be broken. Because the sensitivity of Faraday rotation magnetometry (FRM) depends on optical power rather than intensity, magnetic field sensitivity to be decoupled from spot size.
To leverage this benefit, two key improvements were required. First, we developed a new ma- terial to enhance sensitivity potential. Second, we optimized the sensing architecture to maximize performance using this newly developed transducer.
We discovered that a nanocomposite of terbium-doped magnetite nanoparticles embedded in a polymer host produced an extremely high Verdet constant while maintaining good optical clarity. However, the material exhibited a low optical damage threshold, which limited performance when tightly focused optical spots were used. Since magnetic field sensitivity can be improved by increasing optical power, this low optical damage threshold posed a problem.
To address this issue, we employed a non-common path heterodyne detection scheme. This approach allowed most of the light to bypass the sample, reducing illumination power while mixing the beams on the detector. This amplified the signal above the electronic noise floor, enabling shot-noise-limited measurements even with low optical illumination power. Using this method, we iii achieved a sensitivity of 568 nT/√Hz in our magnetometer.
Further exploration, inspired by polarization-sensitive optical coherence tomography, led us to propose an alternative and novel detection architecture called dual-balanced heterodyne detection (DBHD). This approach altered the power scaling of the measurement, providing additional signal amplification at low magnetic fields. This technique initially had potential to achieve pT/Hz sensitivity. A proof-of-concept device was implemented to validate the hypothesis. However, after extensive experimental work, I concluded that the sensitivity potential was not realizable due to nonlinear scaling of the noise. Though we explore some potential advantages of the technique.
The final part of this dissertation investigates the use of upconversion nanoparticles (UCNPs). These particles are employed in fluorescence microscopy, an imaging technique commonly used in biology to stain samples. UCNPs convert two low-energy photons into one higher-energy photon, enabling background-free measurements because the illumination light differs from the detection light. However, UCNPs are limited by their low photon absorption probability.
We hypothesized that the brightness of UCNPs could be increased using paired photons to enable instantaneous upconversion attempts. A rate-equation model was developed to simulate the dynamics of the nanoparticles. We found that the threshold for brightness enhancement between biphoton and conventional illumination depends on the lifetime of singly excited electrons. In our material, this lifetime is on the order of milliseconds. The threshold for enhancement was so low that it would produce fewer than one photon per second, rendering experimental pursuit impractical.
In summary, this dissertation examines two different systems, both with imaging applications, that leverage the properties of nanoparticles to enhance sensing. The magnetite nanoparticles enabled highly sensitive measurements when combined with a novel detection configuration. Meanwhile, the UCNP nanoparticles proved too efficient to justify the use of paired photon sources for illumination, as their performance could not be practically enhanced.</p
Assessing the Influence of Cultural Backgrounds on Lighting Preferences and Their Impact on Visual Performance
Get PDFThe aim of this study was to determine whether different cultural backgrounds influence visual performance and lighting preferences under various lighting scenes that vary in illuminance and correlated color temperature. Previous research identified cross-cultural differences in mood and preferences; however, no clear link has been established between these factors and visual performance. This study aims to address this gap by conducting an experiment in an office-like setting, where participants completed a cognitive task under six lighting conditions. A total of 27 participants from three world regions were involved. Results showed differences in performance between cultures, with sleep and culture emerging as the most significant factors. Lighting conditions had no effect on performance, suggesting that other cultural or environmental factors may play a stronger role. While preferences for lighting varied across cultures, no correlation was found between lighting preferences and visual performance. Future research should investigate additional factors that influence visual performance to ensure the needs of the diverse group of people working in offices and schools.</p
Contrasting Trends in Colorado Fire Weather Index from Reanalysis and Observations
Get PDFRecent wildfires in Colorado raise the question of whether rising global temperatures have increased fire weather occurrences in Colorado. The U.S. National Weather Service defines fire weather as when "forecast weather conditions will result in a significant threat for the ignition and/or spread of wildfires''. We use two datasets to address the question: “How has the occurrence of fire weather changed in Colorado?” Using 22 years of observed weather conditions from a meteorological tower at the National Renewable Energy Laboratory and 67 years of ERA5 reanalysis data, we assess changing trends in Colorado fire weather occurrences. Additionally, we explore if the difference in recorded wind speeds between observational data and reanalysis data can be explained by differences in spatial and temporal resolution, and what are the implications in the context of quantifying fire weather occurrences. The observational data are limited in temporal extent and spatial representativeness, but they capture exact real-world conditions at a location in complex terrain. The reanalysis data are available for an extended period of time and for the entire state, but the data are of relatively coarse spatial and temporal resolution and may fail to capture extremes. To quantify fire risk, we calculate the Hot-Dry-Windy Index (HDWI), which relies on wind speed and vapor pressure deficit. No statistically significant trend in the HDWI appears in the observational dataset. However, according to the reanalysis data, strong increasing trends in HDWI values emerge across all of Colorado. This apparent conflict between observational and reanalysis data suggests that reanalysis data may not be representative and more long-term observational datasets are required to assess fire risk.</p
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