Theses and Dissertations at Montana State University (MSU)
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Item Analysis of dynamic biological systems imagery(Montana State University - Bozeman, College of Letters & Science, 2022) Dudiak, Cameron Drew; Chairperson, Graduate Committee: Scott McCallaBiological systems pose considerable challenges when attempting to isolate experimental variables of interest and obtain viable data. Developments in image analysis algorithms and techniques allow for further mathematical interpretation, model integration, and even model optimization ('training'). We formulate two distinct methods for obtaining robust quantitative data from time-series imagery of two biological systems: Paenibacillus dendritiformis bacterial colonies, and human gastric organoids. Boundary parameterizations of P. dendritiformis are extracted from timelapse image sequences displaying colony repulsion, and are subsequently used to 'train' a previously developed nonlocal PDE model through the means of error minimization between observation and simulation. Particle tracking is conducted for small colloidal beads embedded within human gastric organoids, and then used to perform particle tracking analysis. This information is analyzed to quantify the local complex viscoelastic properties of organoids' interior mucosal environment.Item Using time lapse photography to document terrain preferences of backcountry skiers(Montana State University - Bozeman, College of Letters & Science, 2018) Saly, Diana Ilona Patricia; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Karl W. Birkeland, Stuart Challender and Jerry Johnson were co-authors of the article, 'Using time lapse photograpy to document terrain preferences of backcountry skiers' submitted to the journal 'Journal of outdoor recreation and tourism' which is contained within this thesis.Avalanches are one of the greatest hazards for those recreating in snow covered mountainous terrain. In the past 20 years an average of 13 people in Canada and 27 people in the US are killed in avalanches each winter. Meanwhile, uncontrolled backcountry avalanche terrain use has significantly increased demonstrated by increased demand for avalanche education and increased sales in backcountry equipment. Lift-accessed backcountry (LABC), or avalanche terrain easily accessed from the ski resort, has seen increased usage since resorts opened boundaries in the mid-1990s. This has led to increased research interest in how people are using backcountry avalanche terrain. A simple method to reduce exposure to avalanche hazard is avoidance, however total avoidance is seldom practical. Professionals and recreational skiers alike mitigate avalanche hazard by managing exposure to terrain containing the avalanche hazard. Current research studies use GPS tracking to study the terrain metrics of backcountry skiers. This GPS research is limited to studying volunteers and professionals that willingly track and submit their trips. This approach ignores many users and thus presents a biased picture of use. This paper develops a method to capture the terrain metrics of all skiers on an avalanche-prone backcountry slope. A remote time-lapse camera focused on a high skier-use backcountry slope, (Saddle Peak, in the Bridger Mountain Range of southwest Montana, USA) captured skiers descending Saddle Peak in ten-second increments. Skier locations were digitized from the photos, then transformed onto a geo-referenced digital elevation model (DEM) such that terrain metrics could be applied to each skier location. Analysis of terrain metrics for each skier point compared slope, profile curvature (downslope), and plan curvature (cross slope) over days with different forecasted avalanche hazard. Terrain metrics on Considerable avalanche hazard days differed significantly from Moderate or Low avalanche hazard days (p-value < 0.001). Transformed data fell within a 49-m horizontal accuracy for all skier point locations with a 95% confidence interval. By capturing all skiers on a slope without their knowledge, the data collected provides a large and diverse data set of the terrain preferences of backcountry skiers under varying conditions.Item Sympathetic ganglia formation in the chick peripheral nervous system(Montana State University - Bozeman, College of Letters & Science, 2005) Kasemeier-Kulesa, Jennifer Caroline; Chairperson, Graduate Committee: Frances Lefcort.The neural crest is a unique population of pluripotent cells that are crucial in vertebrate embryogenesis. In the trunk, NCCs migrate along a ventromedial pathway give rise to the dorsal root ganglia or the sympathetic ganglia (SG), or follow a dorsolateral pathway and give rise to melanocytes. Intriguingly, NCCs following the ventromedial pathway migrate in a metameric pattern through the rostral half somite and avoid the caudal somite and this is thought to dictate the metameric pattern of the SG. Static analyses have characterized the development of these structures, but timelapse imaging of NCCs in their normal environment could potentially reveal unidentified cellular and molecular interactions integral to SG development. However, because NCCs migrate deep within the embryo, it is challenging to track NCCs little is known about the cellular mechanisms mediating their migration, aggregation and differentiation. Here, we follow fluorescently labeled trunk NCCs using a novel sagittal explant culture system and timelapse confocal microscopy. We show trunk NCCs migrate in chain-like formations, and restriction to the rostral somite is not maintained once these cells arrive at the dorsal aorta. Instead, discrete SG only arise after an intermixing of cells along the ventral border of the somite followed by segregation into ganglia. The diverse cell migratory behaviors and active reorganization at the target sites suggest that cell-cell and cell-environment interactions are coordinated with dynamic molecular processes. In a screen for molecules expressed on NCCs during SG formation, we identified the cell adhesion molecule N-cadherin expressed once NCCs arrive adjacent to the dorsal aorta and form ganglia. Additionally, altering cadherin function drastically alters ganglia size. Additionally, we found EphrinB1 expression was absent adjacent to the dorsal aorta as NCCs had dispersed in this corridor, but strikingly up-regulated in the inter-ganglionic regions after discrete ganglia formation. The ephrinB1 receptor, EphB2, is also expressed on NCCs distributed adjacent to the dorsal aorta when discrete ganglia form. Altering ephrinB1/EphB2 signaling interferes with formation of the primary SG chain and blocks the formation of discrete ganglia. Taken together, these results indicate the importance of adhesive and inhibitory mechanisms in the formation of SG.