Poster 30 – Undergraduate Research Symposium Abstracts

The Effect of Muscle Strength on Performance during the Sit-to-Walk Task in Elderly Subjects

Presenter: Hannah Miller

Mentor: Li Shan Chou

PM Poster Presentation

Poster 30

Aging results in declines in many physiological functions, which can negatively affect the performance of everyday activities such as mov- ing from a sitting position to walking. This study was intended to determine how decreases in lower extremity strength can negatively influence elderly performance during Sit-to-Walk, putting them at risk for falling. Forty eight subjects above the age of 70 were recruited to perform the Timed-Up-and-Go (TUG) as well as strength tests targeting hip abductors, knee extensors and ankle dorsiflexors. Lower strength subjects took longer to complete the TUG test. Smaller GRFs were correlated with longer duration of TUG, which indicates a decrease in overall performance and a higher probability of falling as a result of poor muscle strength. This study provides an explanation to how muscle strength correlates with performance in terms of GRF’s and time.

Variation Through Tooth Wear Obscures the Differential Diagnoses of the Fossil Beavers Dipoides stirtoni and Dipoides smithi

Presenter : Savannah Olroyd

Mentor : Sam Hopkins

Major : Biology

Poster 30

Diagnostic features that show variation can be problematic when their variation interferes with clear distinction between species. Fossil identification can be further confounded when highly variable supposedly diagnostic dental characters change with tooth wear. The fossil beavers Dipoides stirtoni and Dipoides smithi are distinguished from one another by the presence or absence of striations on the fourth premolars. D. stirtoni has a parastria running down the cheek side of the upper P4 and a parastriid on the tongue side of the lower p4 in all wear stages. D. smithi lacks the parastria and only occasionally has a parastriid in later wear stages.

We have reviewed this diagnosis by examining over 200 cheek teeth of both species. No well-worn upper P4s of D. smithi have a para- stria, but the parastria is present in the earlier wear stages of all upper cheek teeth. Approximately 25% of the lower p4s of D. smithi studied have a parastriid in later wear stages, and one D. stirtoni lower p4 had no parastriid. We investigated other dental characters to see if other features were diagnostic to these species. The two are indistinguishable in tooth size, molar shape, and wear stages. The cur- rent diagnosis makes confident identification of new specimens difficult unless the specimen includes a well-worn upper P4. Complex series of tooth wear can produce a large amount of apparent dental variation in mammals with high-crowned teeth. Caution should be taken when using dental characters to assign diagnoses to such taxa.

University of Oregon’s Environmental Leadership Program: Critters and Currents Environmental Education Team

Presenter: Makenzie Shepherd

Mentor: Katie Lynch

Poster: 30

Major: Environmental Studies

The prominence of technology and urbanization in the 21st century has established a concrete distinction between the urban and natural worlds. Younger generations, increasingly disengaged and separated from their local natural environments, are exhibiting symptoms of what is colloquially called “nature-deficit disorder.” Marked by rising levels of ADD/ADHD, obesity, depression, and muted creativity, nature-deficit disorder reflects a concerning trend that will accelerate if not immediately and holistically addressed. As the 2014 Critters and Currents team of the Environmental Leadership Program at the University of Oregon, it is our mission to bridge the gap between youth in Eugene, OR and their environment by inspiring them to form connections with the McKenzie River Watershed. Our place-based environmental education curriculum emphasizes hands-on learning by providing creative, collaborative, and physically active lessons that challenge our students to engage the senses and think critically about the local environment and our interdependence with it. Scavenger hunts, field journaling, and storytelling are all activities that empower our students with the attitudes, skills, knowledge, and confidence to create and maintain a strong bond with nature. It is crucial that younger generations restore this connection because our youth have the potential to transform the ways in which our society views and interacts with nature. The Critters & Currents curriculum promotes environmental awareness, inspires respect and compassion for the natural world, and encourages positive environmental action now and in the future.

The Colossal Hats (pukao) of Monumental Statues: An Analysis of Shape Variability among the pukao of Rapa Nui

Presenter: Sean Hixon

Mentors: Terry Hunt, Honors College Anthropology; Carl Lipo, CA State Anthropology

Poster: 30

Major: Geology and Anthropology

As part of monumental statue (moai) construction during the prehistory of Rapa Nui, islanders quarried bodies of red scoria, carved them into hats (pukao), and placed them atop statues measuring up to 10 meters tall. Despite overall great interest in moai and the improbable magnitude of pukao that were raised to reach their positions on the heads of statues, few studies have investigated pukao production and transport. This study seeks to analyze three-dimensional variability of pukao using 15,000 photos of 50 pukao found near statues and 13 red scoria cylinders located in quarries. Three-dimensional computer models based on these photos are used to evaluate which surface features are stylistic with associated temporal and spatial variability and which are functional and relate to construction and transport of these multi-ton objects. The functional detail has the potential to shed light on how prehistoric islanders designed pukao to be placed atop moai. To this end, additional three-dimensional models of statue platforms (ahu) and moai are combined with the models of pukao to test the feasibility of the conventional hypothesis that the pukao were placed atop moai using stone ramps.

Fatiguing During Repetitive Sit-To-Stand Movement: How Can We Tell

Presenter(s): Spencer Smith − Human Physiology, Psychology

Faculty Mentor(s): Li-Shan Chou, Teresa Chen

Poster 30

Research Area: Biomechanics

Funding: Undergraduate Research Opportunity Program Mini Grant

The biomechanically challenging sit-to-stand (STS) task, in which subjects repeatedly sit on and stand up from a chair, has been widely used as a functional mobility assessment as well as fatigue protocol. The purpose of this study was to identify the biomechanical measures that could potentially indicate muscle fatigue during repetitive STS movement. Subjects sat on an armless chair with their shanks perpendicular to the floor and were instructed to perform a repetitive STS movement at a self-selected pace, with arms across the chest for 30 minutes. The center of mass (CoM) trajectory on the sagittal plane (plane that divides body into left and right) was plotted and the area enclosed by rising and falling trajectories was calculated (CoMarea). No significant difference of CoMarea from start to finish was found. However, different changing patterns were observed between participants who were able to finish the fatigue protocol (Groupfinish) and those who failed to complete the task (Groupfail). CoMarea in Groupfail was significantly larger than Groupfinish during the first 3 durations (0-60% of STS protocol), indicated by independent t test, p < .05. In Groupfail, CoMarea has a higher value during 20-40% of the STS protocol, while it showed lower values at beginning and end stages.

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The role of limb dominance in visuoproprioceptive tasks

Presenter(s): Kieley Trempy

Faculty Mentor(s): Kate Spitzley & Andy Karduna

Poster 30

Session: Sciences

Movement is the product of sensory input, mainly from vision and proprioception, and motor output. Vision is the sense of the surrounding space and proprioception is the sense of the body’s position in space. Joint position sense (JPS) is commonly used as a measure of proprioception. JPS of the dominant and nondominant shoulder was measured in healthy subjects to quantify error in a JPS task with and without visual information. Previous studies have examined sensory differences in limb dominance with conflicting results. Some have shown that no differences exist, while others show that movements with the dominant arm rely more on visual information and movements with the nondominant arm rely more on proprioceptive information. The latter theory is illustrated in activities of daily living, such as with preparing food, where the dominant arm uses a knife by viewing the movement while the nondominant arm guides the food by feeling the movement. It was hypothesized that in a JPS task, the dominant arm would have less error with visual information whereas the nondominant arm would have less error without visual information. Subjects wore a virtual reality headset with a tracker on their arm while performing a JPS task. Using the headset, subjects were presented with either a visual representation of their arm location or no visual information about arm location. No difference was found between sides. However, difference was seen between the vision and no vision conditions regardless of limb dominance. Higher error with no vision indicates that proprioception alone is not as effective in driving accurate movements as the combination of vision and proprioception. Future studies analyzing the contributions of vision and proprioception to movement may rule out variation associated with limb dominance.

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