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• 1. [Article] Comprehensive examination of the differences in thermoregulatory and ventilatory responses between humans with and without a PFO under different environmental conditions

  The existence of a patent foramen ovale (PFO) has been known about for nearly 2,000 years. The prevalence of a PFO has been shown to be 25-40% in the general population. Despite the fact that blood flowing ...

  Citation × Citation Citation Abstract Copy Title: Comprehensive examination of the differences in thermoregulatory and ventilatory responses between humans with and without a PFO under different environmental conditions Author: Davis, James Year: 2016 The existence of a patent foramen ovale (PFO) has been known about for nearly 2,000 years. The prevalence of a PFO has been shown to be 25-40% in the general population. Despite the fact that blood flowing through a PFO acts as a shunt, there has been little research looking at the effect a PFO has on physiology in otherwise healthy humans. In Chapter IV, the effect of a PFO on core temperature (Tcore) prior to, and during exercise, was investigated. The design of this experiment included appropriate controls for a thermoregulatory study (i.e. measuring at same time of day, appropriate hydration and food intake, etc.). Results from this study indicate that subjects with a PFO (PFO+) have a Tcore that is ~0.4°C higher at rest and during exercise than subjects without a PFO (PFO–). Additionally, this study showed that PFO– subjects do not increase Tcore to the same extent breathing cold air as they do breathing ambient air during a 10-minute exercise bout, whereas there was no difference in Tcore increase between these two conditions for PFO+ subjects. These findings suggest that the difference in Tcore between PFO+ and PFO– subjects is potentially due to differences in respiratory heat loss. The studies for Chapter V examined differences in thermoregulatory and ventilatory responses during hot water (40°C) and cold water (20°C) immersion. This study found that compared to PFO– subjects, PFO+ subjects 1) increase Tcore at the same rate during hot water immersion and 2) do not cool off as quickly during cold water immersion. Additionally, in subjects who reached a ventilatory threshold, PFO+ subjects had blunted ventilatory responses to increased Tcore compared to PFO– subjects. Finally, in Chapter VI it was shown that PFO+ subjects have blunted ventilatory responses during acute exposure to hyperoxic and normoxic hypercapnia. However, there were no differences in ventilatory responses between PFO+ and PFO– subjects during exposure to either isocapnic or poikilocapnic hypoxia. These findings suggest that PFO+ subjects have a blunted central chemoreflex. This dissertation contains previously, unpublished co-authored material. Title: Comprehensive examination of the differences in thermoregulatory and ventilatory responses between humans with and without a PFO under different environmental conditions Author: Davis, James Year: 2016 The existence of a patent foramen ovale (PFO) has been known about for nearly 2,000 years. The prevalence of a PFO has been shown to be 25-40% in the general population. Despite the fact that blood flowing through a PFO acts as a shunt, there has been little research looking at the effect a PFO has on physiology in otherwise healthy humans. In Chapter IV, the effect of a PFO on core temperature (Tcore) prior to, and during exercise, was investigated. The design of this experiment included appropriate controls for a thermoregulatory study (i.e. measuring at same time of day, appropriate hydration and food intake, etc.). Results from this study indicate that subjects with a PFO (PFO+) have a Tcore that is ~0.4°C higher at rest and during exercise than subjects without a PFO (PFO–). Additionally, this study showed that PFO– subjects do not increase Tcore to the same extent breathing cold air as they do breathing ambient air during a 10-minute exercise bout, whereas there was no difference in Tcore increase between these two conditions for PFO+ subjects. These findings suggest that the difference in Tcore between PFO+ and PFO– subjects is potentially due to differences in respiratory heat loss. The studies for Chapter V examined differences in thermoregulatory and ventilatory responses during hot water (40°C) and cold water (20°C) immersion. This study found that compared to PFO– subjects, PFO+ subjects 1) increase Tcore at the same rate during hot water immersion and 2) do not cool off as quickly during cold water immersion. Additionally, in subjects who reached a ventilatory threshold, PFO+ subjects had blunted ventilatory responses to increased Tcore compared to PFO– subjects. Finally, in Chapter VI it was shown that PFO+ subjects have blunted ventilatory responses during acute exposure to hyperoxic and normoxic hypercapnia. However, there were no differences in ventilatory responses between PFO+ and PFO– subjects during exposure to either isocapnic or poikilocapnic hypoxia. These findings suggest that PFO+ subjects have a blunted central chemoreflex. This dissertation contains previously, unpublished co-authored material. Close

• 2. [Article] Emergent thermodynamics in a system of macroscopic, chaotic surface waves

  The properties of conventional materials are inextricably linked with their molecular composition; to make water flow like wine would require changing its molecular identity. To circumvent this restriction, ...

  Citation × Citation Citation Abstract Copy Title: Emergent thermodynamics in a system of macroscopic, chaotic surface waves Author: Welch, Kyle Year: 2016 The properties of conventional materials are inextricably linked with their molecular composition; to make water flow like wine would require changing its molecular identity. To circumvent this restriction, I have contstructed and characterized a two-dimensional metafluid, so-called because its constitutive dynamics are derived not from atoms and molecules but from macroscopic, chaotic surface waves excited on a vertically agitated fluid. Unlike in conventional fluids, the viscosity and temperature of this metafluid are independantly tunable. Despite this unconventional property, our system is surprisingly consistent with equilibrium thermodynamics, despite being constructed from macroscopic, non-equilibrium elements. As a programmable material, our metafluid represents a new platform on which to study complex phenomena such as self-assembly and pattern formation. We demonstrate one such application in our study of short-chain polymer analogs embedded in our system. Title: Emergent thermodynamics in a system of macroscopic, chaotic surface waves Author: Welch, Kyle Year: 2016 The properties of conventional materials are inextricably linked with their molecular composition; to make water flow like wine would require changing its molecular identity. To circumvent this restriction, I have contstructed and characterized a two-dimensional metafluid, so-called because its constitutive dynamics are derived not from atoms and molecules but from macroscopic, chaotic surface waves excited on a vertically agitated fluid. Unlike in conventional fluids, the viscosity and temperature of this metafluid are independantly tunable. Despite this unconventional property, our system is surprisingly consistent with equilibrium thermodynamics, despite being constructed from macroscopic, non-equilibrium elements. As a programmable material, our metafluid represents a new platform on which to study complex phenomena such as self-assembly and pattern formation. We demonstrate one such application in our study of short-chain polymer analogs embedded in our system. Close

• 3. [Article] A Hierarchical Modeling Approach to Simulating the Geomorphic Response of River Systems to Climate Change

  Anthropogenic climate change significantly affects water resources. River flows in mountainous regions are driven by snowmelt and are therefore highly sensitive to increases in temperature resulting from ...

  Citation × Citation Citation Abstract Copy Title: A Hierarchical Modeling Approach to Simulating the Geomorphic Response of River Systems to Climate Change Author: Praskievicz, Sarah Year: 2014 Anthropogenic climate change significantly affects water resources. River flows in mountainous regions are driven by snowmelt and are therefore highly sensitive to increases in temperature resulting from climate change. Climate-driven hydrological changes are potentially significant for the fluvial geomorphology of river systems. In unchanging climatic and tectonic conditions, a river's morphology will develop in equilibrium with inputs of water and sediment, but climate change represents a potential forcing on these variables that may push the system into disequilibrium and cause significant changes in river morphology. Geomorphic factors, such as channel geometry, planform, and sediment transport, are major determinants of the value of river systems, including their suitability for threatened and endangered species and for human uses of water. This dissertation research uses a hierarchical modeling approach to investigate potential impacts of anthropogenic climate change on river morphology in the interior Pacific Northwest. The research will address the following theoretical and methodological objectives: 1) Develop downscaled climate change scenarios, based on regional climate-model output, including changes in daily minimum and maximum temperature and precipitation. 2) Estimate how climate change scenarios affect river discharge and suspended-sediment load, using a basin-scale hydrologic model. 3) Examine potential impacts of climate-driven hydrologic changes on stream power and shear stress, bedload sediment transport, and river morphology, including channel geometry and planform. The downscaling approach, based on empirically-estimated local topographic lapse rates, produces high-resolution climate grids with positive forecast skill. The hydrologic modeling results indicate that projected climate change in the study rivers will change the annual cycle of hydrology, with increased winter discharge, a decrease in the magnitude of the spring snowmelt peak, and decreased summer discharge. Geomorphic modeling results suggest that changes in reach-averaged bedload transport are highly sensitive to likely changes in the recurrence interval of the critical discharge needed to mobilize bed sediments. This dissertation research makes an original contribution to the climate-change impacts literature by linking Earth processes across a wide range of spatial scales to project changes in river systems that may be significant for management of these systems for societal and ecological benefits. This dissertation includes unpublished co-authored material. Title: A Hierarchical Modeling Approach to Simulating the Geomorphic Response of River Systems to Climate Change Author: Praskievicz, Sarah Year: 2014 Anthropogenic climate change significantly affects water resources. River flows in mountainous regions are driven by snowmelt and are therefore highly sensitive to increases in temperature resulting from climate change. Climate-driven hydrological changes are potentially significant for the fluvial geomorphology of river systems. In unchanging climatic and tectonic conditions, a river's morphology will develop in equilibrium with inputs of water and sediment, but climate change represents a potential forcing on these variables that may push the system into disequilibrium and cause significant changes in river morphology. Geomorphic factors, such as channel geometry, planform, and sediment transport, are major determinants of the value of river systems, including their suitability for threatened and endangered species and for human uses of water. This dissertation research uses a hierarchical modeling approach to investigate potential impacts of anthropogenic climate change on river morphology in the interior Pacific Northwest. The research will address the following theoretical and methodological objectives: 1) Develop downscaled climate change scenarios, based on regional climate-model output, including changes in daily minimum and maximum temperature and precipitation. 2) Estimate how climate change scenarios affect river discharge and suspended-sediment load, using a basin-scale hydrologic model. 3) Examine potential impacts of climate-driven hydrologic changes on stream power and shear stress, bedload sediment transport, and river morphology, including channel geometry and planform. The downscaling approach, based on empirically-estimated local topographic lapse rates, produces high-resolution climate grids with positive forecast skill. The hydrologic modeling results indicate that projected climate change in the study rivers will change the annual cycle of hydrology, with increased winter discharge, a decrease in the magnitude of the spring snowmelt peak, and decreased summer discharge. Geomorphic modeling results suggest that changes in reach-averaged bedload transport are highly sensitive to likely changes in the recurrence interval of the critical discharge needed to mobilize bed sediments. This dissertation research makes an original contribution to the climate-change impacts literature by linking Earth processes across a wide range of spatial scales to project changes in river systems that may be significant for management of these systems for societal and ecological benefits. This dissertation includes unpublished co-authored material. Close

• 4. [Article] MORPHOLOGICAL VARIATION OF PISASTER OCHRACEUS IN RESPONSE TO WAVE EXPOSURE

  52 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2...

  Citation × Citation Citation Abstract Copy Title: MORPHOLOGICAL VARIATION OF PISASTER OCHRACEUS IN RESPONSE TO WAVE EXPOSURE Author: Bjorkquist, Alyssa Year: 2016 52 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Title: MORPHOLOGICAL VARIATION OF PISASTER OCHRACEUS IN RESPONSE TO WAVE EXPOSURE Author: Bjorkquist, Alyssa Year: 2016 52 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Close

• 5. [Article] NITRIC OXIDE SIGNALLING PATHWAYS FOLLOWING CHRONIC PASSIVE HEAT THERAPY

  64 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, ...

  Citation × Citation Citation Abstract Copy Title: NITRIC OXIDE SIGNALLING PATHWAYS FOLLOWING CHRONIC PASSIVE HEAT THERAPY Author: Eymann, Taylor Year: 2016 64 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Title: NITRIC OXIDE SIGNALLING PATHWAYS FOLLOWING CHRONIC PASSIVE HEAT THERAPY Author: Eymann, Taylor Year: 2016 64 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Close

• 6. [Article] EFFECTS OF ACUTE PASSIVE HEAT EXPOSURE

  42 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, ...

  Citation × Citation Citation Abstract Copy Title: EFFECTS OF ACUTE PASSIVE HEAT EXPOSURE Author: Harris, Sarianne Year: 2016 42 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Title: EFFECTS OF ACUTE PASSIVE HEAT EXPOSURE Author: Harris, Sarianne Year: 2016 42 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Close

• 7. [Article] THE EFFECT OF A PATENT FORAMEN OVALE ON THERMOREGULATORY AND VENTILATORY RESPONSES DURING PASSIVE HEATING AND COOLING

  41 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, ...

  Citation × Citation Citation Abstract Copy Title: THE EFFECT OF A PATENT FORAMEN OVALE ON THERMOREGULATORY AND VENTILATORY RESPONSES DURING PASSIVE HEATING AND COOLING Author: Hay, Madeline Year: 2016 41 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Title: THE EFFECT OF A PATENT FORAMEN OVALE ON THERMOREGULATORY AND VENTILATORY RESPONSES DURING PASSIVE HEATING AND COOLING Author: Hay, Madeline Year: 2016 41 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016. Close

• 8. [Article] Chronic passive heat therapy as a novel means of improving vascular function in sedentary humans

  Cardiovascular disease is the leading cause of death in the developed world. The majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial ...

  Citation × Citation Citation Abstract Copy Title: Chronic passive heat therapy as a novel means of improving vascular function in sedentary humans Author: Brunt, Vienna Year: 2016 Cardiovascular disease is the leading cause of death in the developed world. The majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial dysfunction and arterial stiffening. Passive heat stress results in elevations in core temperature (inducing heat shock protein expression) and changes in cardiovascular hemodynamics, such as increased cardiac output and shear stress, that are similar to exercise. Thus, repeated passive heat stress (“heat therapy”) may provide an alternative means of improving cardiovascular health, particularly for patients with limited exercise tolerance and/or capabilities. Therefore, the goal of this dissertation was to perform integrative studies to determine the effects of heat therapy on vascular function and the associated cellular pathways in young, sedentary humans. Twenty subjects were assigned to participate in 8 weeks (4-5x/week) of heat therapy (N=10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ≥38.5°C for 60 min/session) or thermoneutral water immersion (N=10; sham). As discussed in Chapter V, we found that heat therapy improved numerous well-established biomarkers of conduit vessel/macrovascular function, including flow-mediated dilation (a measure of endothelial function), arterial stiffness, intima media thickness, and blood pressure. Heat therapy also improved microvascular function, as discussed in Chapter VI, measured as improved cutaneous thermal hyperemia and nitric oxide-dependent dilation (the difference between microdialysis sites receiving Lactated Ringer’s [control] and nitric oxide synthase inhibition). No changes were observed in any variables in sham subjects. In Chapter VII, we showed that both direct cellular heating and serum collected from human subjects following heat therapy improved nitric oxide bioavailability and angiogenesis in cultured endothelial cells, providing potential mechanisms by which heat therapy improves vascular function in vivo. Therefore, the studies described herein provide comprehensive evidence that passive heat therapy improves vascular health and insight into the mechanisms involved. Our data presented in Chapters IV-VII, combined with pilot data we conducted in spinal cord injured individuals (Chapter VIII), strongly indicate that passive heat therapy could be used as a simple and effective tool to improve cardiovascular health in a variety of patient populations. This dissertation includes published and unpublished co-authored material. Title: Chronic passive heat therapy as a novel means of improving vascular function in sedentary humans Author: Brunt, Vienna Year: 2016 Cardiovascular disease is the leading cause of death in the developed world. The majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial dysfunction and arterial stiffening. Passive heat stress results in elevations in core temperature (inducing heat shock protein expression) and changes in cardiovascular hemodynamics, such as increased cardiac output and shear stress, that are similar to exercise. Thus, repeated passive heat stress (“heat therapy”) may provide an alternative means of improving cardiovascular health, particularly for patients with limited exercise tolerance and/or capabilities. Therefore, the goal of this dissertation was to perform integrative studies to determine the effects of heat therapy on vascular function and the associated cellular pathways in young, sedentary humans. Twenty subjects were assigned to participate in 8 weeks (4-5x/week) of heat therapy (N=10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ≥38.5°C for 60 min/session) or thermoneutral water immersion (N=10; sham). As discussed in Chapter V, we found that heat therapy improved numerous well-established biomarkers of conduit vessel/macrovascular function, including flow-mediated dilation (a measure of endothelial function), arterial stiffness, intima media thickness, and blood pressure. Heat therapy also improved microvascular function, as discussed in Chapter VI, measured as improved cutaneous thermal hyperemia and nitric oxide-dependent dilation (the difference between microdialysis sites receiving Lactated Ringer’s [control] and nitric oxide synthase inhibition). No changes were observed in any variables in sham subjects. In Chapter VII, we showed that both direct cellular heating and serum collected from human subjects following heat therapy improved nitric oxide bioavailability and angiogenesis in cultured endothelial cells, providing potential mechanisms by which heat therapy improves vascular function in vivo. Therefore, the studies described herein provide comprehensive evidence that passive heat therapy improves vascular health and insight into the mechanisms involved. Our data presented in Chapters IV-VII, combined with pilot data we conducted in spinal cord injured individuals (Chapter VIII), strongly indicate that passive heat therapy could be used as a simple and effective tool to improve cardiovascular health in a variety of patient populations. This dissertation includes published and unpublished co-authored material. Close

• 9. [Article] Forgetting Nature: The Importance of Including Environmental Flows in International Water Agreements

  34 pages

  Citation × Citation Citation Abstract Copy Title: Forgetting Nature: The Importance of Including Environmental Flows in International Water Agreements Author: Hardberger, Amy Year: 2016 34 pages Title: Forgetting Nature: The Importance of Including Environmental Flows in International Water Agreements Author: Hardberger, Amy Year: 2016 34 pages Close

• 10. [Article] Modeling Circulation Dynamics and Submarine Melt in Greenland Fjords

  Meltwater accumulated on the Greenland Ice Sheet drains to glacier beds, discharging into fjords hundreds of meters below sea level. The injection of meltwater at depth generates an upwelling plume that ...

  Citation × Citation Citation Abstract Copy Title: Modeling Circulation Dynamics and Submarine Melt in Greenland Fjords Author: Carroll, Dustin Year: 2017 Meltwater accumulated on the Greenland Ice Sheet drains to glacier beds, discharging into fjords hundreds of meters below sea level. The injection of meltwater at depth generates an upwelling plume that entrains warm ocean water as it rises along the terminus, increasing submarine melt and driving a fjord-scale exchange flow. However, due to sparse ocean-glacier observations, we lack a process understanding of how plumes control fjord circulation and submarine melt. Combining numerical modeling, theory, and observations, this dissertation investigates near-glacier plume dynamics, the influence of glacier depth on plume structure and submarine melt, and the role of fjord-glacier geometry on circulation in tidewater glacier fjords. In Chapter II, I use buoyant plume theory and a nonhydrostatic, three-dimensional ocean–ice model to investigate the sensitivity of plume dynamics to subglacial discharge, turbulent diffusivity, and conduit geometry. Large discharges result in plumes with positive temperature and salinity anomalies in the upper water column. Fjord circulation is sensitive to conduit geometry; distributed subglacial discharge results in a stronger return flow of warm water toward the terminus. In Chapter III, I use buoyant plume theory, initialized with realistic ranges of subglacial discharge, glacier depth, and ocean stratification, to investigate how plume structure and submarine melt vary during summer months in 12 Greenland fjords. Grounding line depth is a primary control on plume-induced submarine melt: deep glaciers produce warm, salty subsurface plumes that undercut termini, and shallow glaciers produce cold, fresh surface-confined plumes that can overcut. Finally, in Chapter IV, I use regional-scale numerical ocean simulations to systematically evaluate how fjord circulation forced by subglacial plumes, tides, and wind stress depends on fjord width, glacier depth, and sill height. Glaciers grounded below sill depth can draw shelf waters over a shallow sill and into fjord basins with seasonal subglacial discharge; this process is independent of external shelf forcing. These results underscore the first-order effect that subglacial discharge and fjord-glacier geometry have in controlling fjord circulation and, thus, ocean heat flux to the ice. This dissertation includes previously published and co-authored material. Title: Modeling Circulation Dynamics and Submarine Melt in Greenland Fjords Author: Carroll, Dustin Year: 2017 Meltwater accumulated on the Greenland Ice Sheet drains to glacier beds, discharging into fjords hundreds of meters below sea level. The injection of meltwater at depth generates an upwelling plume that entrains warm ocean water as it rises along the terminus, increasing submarine melt and driving a fjord-scale exchange flow. However, due to sparse ocean-glacier observations, we lack a process understanding of how plumes control fjord circulation and submarine melt. Combining numerical modeling, theory, and observations, this dissertation investigates near-glacier plume dynamics, the influence of glacier depth on plume structure and submarine melt, and the role of fjord-glacier geometry on circulation in tidewater glacier fjords. In Chapter II, I use buoyant plume theory and a nonhydrostatic, three-dimensional ocean–ice model to investigate the sensitivity of plume dynamics to subglacial discharge, turbulent diffusivity, and conduit geometry. Large discharges result in plumes with positive temperature and salinity anomalies in the upper water column. Fjord circulation is sensitive to conduit geometry; distributed subglacial discharge results in a stronger return flow of warm water toward the terminus. In Chapter III, I use buoyant plume theory, initialized with realistic ranges of subglacial discharge, glacier depth, and ocean stratification, to investigate how plume structure and submarine melt vary during summer months in 12 Greenland fjords. Grounding line depth is a primary control on plume-induced submarine melt: deep glaciers produce warm, salty subsurface plumes that undercut termini, and shallow glaciers produce cold, fresh surface-confined plumes that can overcut. Finally, in Chapter IV, I use regional-scale numerical ocean simulations to systematically evaluate how fjord circulation forced by subglacial plumes, tides, and wind stress depends on fjord width, glacier depth, and sill height. Glaciers grounded below sill depth can draw shelf waters over a shallow sill and into fjord basins with seasonal subglacial discharge; this process is independent of external shelf forcing. These results underscore the first-order effect that subglacial discharge and fjord-glacier geometry have in controlling fjord circulation and, thus, ocean heat flux to the ice. This dissertation includes previously published and co-authored material. Close