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NEPC Review: Productive Struggle: How Artificial Intelligence is Changing Learning, Effort, and Youth Development in Education (Bellwether, June 2025)
Get PDFA report from Bellwether explores when the ease provided by GenAI promotes learning versus when it becomes a shortcut with hidden costs. It examines AI’s influence on students’ memory, attention, motivation, and self-regulation but conflates key definitions of learning, leading to shaky conclusions. Framed through an overly individualistic lens, it overlooks classroom complexity and fails to offer strategies to prevent harm from GenAI’s use with children and youth. Though it raises important questions, its value for policymakers is limited.</p
German Newspaper Coverage of Climate Change or Global Warming, 2004-2025 - September 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
Latin American Newspaper Coverage of Climate Change or Global Warming, 2005-2025 - September 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
European 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
Finnish 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
Design, Synthesis, and Characterization of Degradable Crosslinked Polymers Towards Reversible Biological Stasis
Get PDFThis thesis explores the degradation of polymer systems through mechanical or hydrolytic mechanisms to firstly, better understand the relationship between polymer network structure and mechanophore reactivity in mechanically labile systems and secondly, to investigate the effect of inducing a reversible intracellular biostasis through the introduction of degradable PEG-based macromers.
The first part of this thesis (Chapter 3) incorporates phthalaldehyde mechanophores into multi-arm poly(ethylene glycol) macromers to create mechanically labile hydrogels. The degradation of these hydrogels was shown to be compatible with the suspension and release of proteins and blood cells without causing complete denaturation or annihilation of the cells. Mechanical stimulation in the presence of mechanophores provides a means of spatiotemporal control, similar to that of photodegradation. This study provides a basis for the use of sonication waves to penetrate biological tissues to activate a mechanically responsive material more uniformly than heat or light stimuli, maintaining spatiotemporal of the stimuli-response.
The following chapter of this thesis (Chapter 4) builds on the understanding of mechanophore activation in crosslinked polymer networks by investigating the difference in mechanophore activation of step versus chain growth crosslinked polymers. Current limitations of this technique include resolution, compatibility of mechanophore units (ie. insolubility or mechanophore activation during the polymerization), and challenging analysis of mechanophores once activated in crosslinked systems. Developing a greater understanding of the polymer factors that influence mechanophore activation and the degradation profile associated with mechanical degradation is of particular interest to facilitate the utilization of mechanophores in more advanced applications as the limitations and intrinsic characteristics of these moieties are better understood. To visualize where and when mechanophores are activated in these networks a mchanofluorophore was used. This study found that the homogeneity of the polymer network plays a role in mechanophore activation, likely due to mechanophores being directionally activated. In heterogeneous, chain growth polymers, the distribution of mechanophores that may be located in network non-idealities (ie. loops or dangling ends) reduces the number of mechanically labile crosslink junctions that are aligned with the direction of an applied uniaxial load. When a dynamic chemistry, disulfides, was added to the step or chain network composition minimal change in these results was observed, likely due to the dynamic chemistry not taking place on the time scale used.
In the second half of this thesis, the degradation characterization techniques and applications outlined in Chapter 3 are employed for hydrolytically degradable materials. This section begins with the design and synthesis of hydrolytically degradable PEG carbamate, carbonate, and ester derivatives and studies their degradation at physiological conditions. Similar to the earlier chapter, these groups were incorporated into PEG macromers which were subsequently used to form hydrogels. These hydrolytically labile macromers were also transfected and crosslinked intracellularly to induce transient cellular quiescence that is shown to be capable of inducing reversible biostasis of cells with 60% of cells treated with the carbonate macromer returning to their proliferative state and rebounding in translational activity after 72 hours. The successfully induced reversible biostasis of these materials facilitates the subsequent chapter where carbonate, anhydride, ester, or dithiolane functionalized multi-arm PEG hydrogel systems are utilized as treatments for partial thickness burns on porcine models. The effects of these treatments is evaluated over a 21 day period with the results finding all the hydrolytically degradable systems to provide positive healing environments that facilitate similar results to the current standard of care for burns compared to untreated wound sites.</p
A Numerical Investigation Into the Asymptotics of Rotationally and Magnetically Constrained Convection
Get PDFNumerical simulations of thermal convection with either rapid rotation or a strong imposed magnetic field are carried out. The scaling of various quantities such as flow speeds, heat transport, and length scales are analyzed for these systems, with a focus on the asymptotic nature of these quantities. The geometry and boundary conditions are varied, with each chapter focusing on a particular configuration.
Chapter two considers a non-conducting fluid contained between rotating spherical shells with no magnetic field. Both the Ekman number and the Rayleigh number are varied in order to study the influence of these parameters. It is found that the asymptotic scaling of the small-scale flow speeds, forces, and some length scales roughly follow the same asymptotic scaling found in quasi-geostrophic plane layer convection. However, due to the use of stress-free boundary conditions, a large-scale zonal flow develops. This large-scale zonal flow follows a different asymptotic dependence than the small-scale flow, and a balance between Reynolds stresses and viscous stresses can be used to determine an asymptotic scaling of the large-scale zonal flow. This suggests that the saturation of the zonal flow occurs when the zonal flow becomes large enough such that the viscous stresses are as large as the Reynolds stresses.
Chapter three considers plane layer convection with an imposed magnetic field. The imposed magnetic field is misaligned with the direction of gravity, forming an angle of 135 degrees. The strength of the magnetic field and Rayleigh number are varied, which allows for a similar analysis as conducted in chapter two. Heat transport and convective flow speeds are found to be similar to the case of a vertical magnetic field, though the tilt of the magnetic field ends up introducing a large-scale horizontal flow. This large-scale flow is again found to result from a balance between the Reynolds stresses and viscous stresses, analogous to the rotating case in chapter two. An empirical asymptotic scaling with respect to magnetic field strength for the small-scale flow speeds is found, which can be used with the Reynolds stress relationship to predict the scaling of the large-scale flow speeds. The balance between the Reynolds stresses and viscous stresses also predicts that the zonal flow speeds should increase as the aspect ratio of the simulation domain is changed, which is confirmed for one case. Horizontally averaged flows and magnetic fields are also investigated, though these are found to be asymptotically small, and so appear to be largely irrelevant when the imposed magnetic field is strong.
Chapter four compares a set of rotating spherical shell dynamo cases with an approximate MAC (magnetic-Archimedes-Coriolis) force balance to otherwise identical non-magnetic cases. Since the magnetic field is self-generated and not imposed, it is the rotation rate of the system which is important to the asymptotics, and the Ekman number dependence of the dynamo and non-magnetic cases is compared. It is found that the flow speeds, the viscous dissipation length scale, the viscous force, and the advective term of the momentum equation follow roughly the same Ekman number dependence for the dynamo and non-magnetic cases. However, owing to the strong influence of the Lorentz force in the dynamo cases, the buoyancy force for the dynamo cases is found to be asymptotically stronger than the buoyancy force in the non-magnetic cases, with the buoyancy force for the dynamo cases entering at the same asymptotic order as the Coriolis force. The reason for this change in the asymptotic size of the buoyancy force is at least partly explained by changes in the dissipation equation: the non-magnetic cases require that all dissipation is viscous, which, under a few assumptions, limits the buoyancy force to be asymptotically the same order as the viscous force. However, the dynamo cases also have magnetic dissipation, so for strong magnetic field strength, the magnetic dissipation can allow the buoyancy force to be asymptotically larger than the viscous force.</p
Advanced Methodologies to Translate High-Level System Requirements into Bounded Metrics to Progress Mechanical Counter-Pressure Spacesuit Technology Maturation
Get PDFThe feasibility of conducting human surface exploration on planetary bodies is largely dependent on the design and implementation of spacesuits. Gas pressure (GP) has successfully served as the pressure system for spacesuits over the past 60 years, but, with a change in operational and environmental demands for Mars, GP may not be feasible due to fundamental limitations. Alternative spacesuit architectures, such as mechanical counter-pressure (MCP) or hybrid systems, offer potential solutions to the current limitations of GP spacesuits. These may include increased mobility, decreased metabolic work, simplified thermal cooling, and increased safety, while potentially decreasing fit-related injuries. Despite the numerous potential advantages, MCP technology development has stalled. While prior efforts have developed high-quality prototypes, there has been increased attention put on establishing design requirements to better drive technology maturation.
This dissertation explores methods for developing MCP spacesuit design requirements for the Martian environment across several critical areas of MCP development. Specifically, this work includes modeling thermal regulation systems, compression garment fabrication, and reliable pressure measurements. In doing so, it takes steps to inform future design requirements that can be used to develop bounded metrics and enable MCP advancements, ultimately taking steps towards making MCP feasible for an operational environment. This research was accomplished through four research Aims.
Aim 1 models active and passive thermal control for different Martian spacesuit architectures including traditional GP, MCP, and a hybrid GP/MCP layered system to demonstrate how this approach can be used to develop environmental, operational, and mission-specific thermal system requirements. The analytical models incorporate the maximum and minimum conditions of the Martian environment. This aim builds from prior efforts but includes for the first time differences in sex and body region. The models were developed using first principles and empirical data from the literature. A sensitivity analysis was performed on suit design parameters to inform which variables are the most useful for engineers to focus on optimizing. The results can be used to inform the design of novel spacesuit architectures to inform thermal regulation estimations for the life support system and provide bounded requirements for supplemental heating and cooling systems.
As technology in the textile industry continues to rapidly progress, novel textile fabrication methods become available for MCP garment production and facilitate design improvements to address the challenges of prior work on MCP system development. Aim 2 investigates advances in materials and whole garment fabrication as a means by which to improve current MCP pressure production performance for the hybrid spacesuit concept with a focus on pressure magnitude and uniformity. By exploring the mechanical characteristics of knit materials and novel knit whole-garment structures, this aim takes steps to integrate advanced knit structures and study MCP pressure production performance with a partial pressure MCP glove as a proof of concept. Exploring these fabrication advancements methods can inform the feasibility of pressure garment development by understanding their capabilities and limitations.
While monitoring the pressure of an MCP spacesuit is critical to the health, safety, and performance of the astronaut, there are currently no low-profile force sensors that can reliably measure the pressure. Identifying design requirements for the development and testing of reliable pressure systems is critical to increase our understanding of the interface between high-performance compression garments and the skin. Aim 3 uses a literature-derived taxonomy to identify functional and fabrication characteristics for on-body pressure measurement systems to design, develop, validate, and monitor MCP technology. In doing so, future sensor development can be directed by identifying sensor characteristics that produce performance metrics that fulfill MCP application requirements.
Finally, Aim 4 provides a synthesis of current MCP literature as well as the results from the previous aims to guide future MCP development. Operational considerations were incorporated to focus on the limitations or benefits of MCP in addressing Martian surface exploration. From the evaluation of each technology gap, recommendations for how to address gaps in future work were determined. Ultimately, a technology development roadmap is proposed leveraging potential fabrication, modeling, and literature analysis methodologies to increase the fundamental understanding of the MCP design space as it relates to Martian surface exploration.</p
Analyzing Periodic Orbit Structures with Applications to Astrodynamics
Get PDFUnderstanding the behavior of chaotic dynamical systems is essential for scientists investigating the formation and evolution of the solar system and for spacecraft mission designers. Equilibrium points and periodic orbits are two of the simplest features that we can reliably use to analyze these systems. While simplified models are useful for a rudimentary analysis into the environments around celestial bodies of interest, higher-fidelity models are known to possess fundamentally different characteristics, resulting in new dynamical structures with qualitatively different behavior. For example, even though the Homogeneous Rotating Gravitating Triaxial Ellipsoid (HRGTE) model can be used to represent motion in the vicinity of a small body, considering a more realistic shape model of the body will destroy the symmetries of the HRGTE. In this work, we use a detailed shape model of the asteroid (101955) Bennu to conduct a detailed analysis of the periodic orbit structure that exists around Bennu. We also present a new method to compute the equilibrium points that exist around small bodies and use it to study the natural evolution of the dynamical environment caused by a change in the body's spin rate as a result of the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect.
As another example, while the Circular Restricted 3-Body Problem (CR3BP) is an autonomous model used to represent motion in cislunar space, increasing the fidelity of the model by adding the effect of the Sun makes the new system non-autonomous. So, we conduct a comprehensive study on the periodic orbit structure in the Sun-Earth-Moon (SEM) Hill Restricted 4-Body Problem (HR4BP) and develop the application of a Melnikov-like function to initialize transitioning resonant periodic orbits from the CR3BP to HR4BP. We also identify and describe the numerical behavior of the Gateway’s planned orbit as a set of periodic orbits foliating a 2-D torus in multiple models representing the SEM system. Finally, we develop a procedure to transition periodic orbits and quasi-periodic orbits (QPOs) from the SEM HR4BP into ephemeris models and prove the robust existence of trajectories around the Gateway’s orbit in a full ephemeris model that are qualitatively similar to 2-D QPOs found in simpler models.</p
Assessing Plant Community Response to Environment, Invasion, and Disturbance for Strategic Management and Restoration
Get PDFConservation and restoration of native biodiversity is a pressing challenge for ecosystem management. Native biodiversity is itself an ecosystem service and supports other services through bolstering ecosystem multifunctionality. Management and restoration require anticipating species interactions within a diverse, dynamic community and with the environment. This is complicated by how changing climate, increasing frequency and intensity of extreme weather and disturbance events, and increasing biological invasion may impact species and modify species interactions. While conservation and restoration were already difficult, shifting conditions and context of this work means managers and restoration practitioners must be strategic in where, when, and how to intervene. I argue through collaborating with practitioners, harnessing broad spatiotemporal, standardized datasets, and leveraging increasingly efficient and powerful computational tools, researchers can produce useful, usable, and timely science to support strategic ecological management and restoration.
This dissertation addresses the challenge of native plant species conservation and restoration in grassland and sagebrush systems across the Western United States. Through observational data synthesis and experimental work, I assessed plant species impacts and community change from environmental variability, climate change, disturbance, and plant invasion.
In Chapter II, I assessed annual invasive grass-fire impacts on regionally common flora in the U.S. Great Basin to identify data-driven post-fire restoration candidates. I identified several native species as robust candidates, including some not often used in restoration. These species could be prioritized for future seed collection and materials development. In Chapter III, I examined the resilience of a xeric tallgrass community to seasonal climate variability and resistance to transient invasion over 27 years. Lack of functional group complementarity in climate responses and the emergence of fall climate as an important driver were among the key findings with implications for management given projected climate change. Finally, in Chapter IV, I examined consequences of precipitation variability and management action for reintroducing native plants to a California non-native annual grassland. Native species seeded recruited to half or more plots and had divergent responses to treatments. This finding encourages using native annual plants in California grassland restoration and using environmental and biotic heterogeneity known in this system to enhance restoration.</p
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