Tag: Physical Science

Climate Change and Snow: How Pollutant Aerosols Impact Snow Grain and Albedo in Seasonal Snow Packs

Presenter(s): Neil Yotsuya − Architecture

Faculty Mentor(s): Dave Sutherland

Poster 194

Research Area: Physical Science

The ability for snow to reflect light, otherwise known as albedo, is plays a key role in both local and global environmental conditions. Snow grain size and snow albedo have a inverse relationship; the larger that a snow grain is, the lower its albedo will tend to be. Environmental factors that impact grain size are many and factors such as solar zenith, aerosol pollutants, time, and extreme weather must all be accounted for when understanding why snow grain changes in size. Crystal metamorphosis, the process by which ground snow increases in grain size, is susceptible to aerosol pollutants. Black Carbon (BC), in particular, is one major pollutant that can increase the speed at which snow grain undergoes metamorphosis. The exact degree to which BC and other aerosols have altered snow albedo of seasonal snowpack near urban regions is still not fully understood. Data seems to show a strong correlation between pollutant level and grain size. However, the amount of pollutants has no direct correlation with albedo. A possible conclusion may be made that, while not directly impacting snowpack albedo, BC and other aerosol pollutants do impact grain size, thereby impacting snowpack albedo. Better understanding how exactly pollution and climate change has impacted snowpack albedo through grain metamorphosis can help us to better understand the exact impact that urban pollution has on local and global environmental factors.

The Effect of Large Circumstellar Disks on the Formation of Short Orbital Period Binary Star Systems

Presenter(s): Carl Ranney − Physics

Faculty Mentor(s): James Imamura

Poster 36

Research Area: Physical Science

The purpose of this research is to determine the validity of the fission model of short orbital period binary star formation. The fission model describes the process in which a protostar with large angular velocities splits into two bodies in orbit around a common center of mass. The fission model is one of the three major models currently under investigation by the wider astrophysical community as possible sources for the formation of short orbital period binary star systems. While fission has not received much attention in the last two decades due to results found in large scale numerical simulations, the advances in computational power now available allow much more complex simulations that show promise in solving this problem. Rather than looking at single stars, we are simulating the evolution of a rotating protostar with a large circumstellar disk that is approaching a reverse Roche limit, where the mass of the disk starts to pull the protostar apart. By including this large disk in our calculations, we find that the prospects for fission is greatly enhanced. We are using the computer code Chymera in Aciss and Talapas, the University of Oregon high-performance computing clusters in our study to simulate the fluid dynamics of this system. Chymera includes many nonlinear instabilities which were not widely known or where undiscovered during the period when the last major simulations of the fission model were attempted. With the combination of these two factors, our research has provided valuable insight into previously unexplored aspects of the complex system.

Controls on glacial retreat in the West Antarctic Peninsula

Presenter(s): Ryan Obermeyer − Math, Spatial Data Science And Technology

Faculty Mentor(s): David Sutherland, Kiya Riverman

Poster 52

Research Area: Physical Science

Funding: NSF grant no. 1543012

The West Antarctic Peninsula has over 300 glaciers, all with unique environmental conditions. The peninsula is losing ice, but it is not fully understood what drives retreat rates for individual glaciers. The Antarctic Peninsula is rich in available data, but comparatively little analysis of glacial environmental controls has been performed. We used a Landsat-7 and laser altimetry derived grounding line, infrared temperature data, bathymetry swath data, Regional Ocean Modeling runs, and calculated retreat rates to find correlations between retreat and environment. Previous work has shown that glaciers in the region are sensitive to ocean temperatures. Glaciers in the northern portion of the peninsula interact with cooler ocean currents and have lower retreat rates than the glaciers in the south. We found a latitudinal cut off, north of which floating glaciers rarely exist. Warmer air temperatures in the northern portion of the peninsula may limit the prevalence of floating glaciers. In contrast, the south with cooler air and warmer water allows glaciers to interact with the ocean. Model runs of Circumpolar Deep Water flow highlight which glaciers are in contact with warmer water. There is correlation between glacial retreat and contact with Circumpolar Deep Water. These findings allow us to predict that as air temperatures in Antarctica continue to rise, the latitudinal cut off for floating glaciers could move south, and less ice will be interacting with the ocean. This means that there is potential for retreat rates to temporarily decline as glaciers will be less affected by ocean temperatures.

Determining Soil Organic Carbon Values in Association With Vegetation Community Types in the Chewaucan River Basin

Presenter(s): Aaron Lefore − Environmental Science

Faculty Mentor(s): Lucas Silva, Schyler Reis

Poster 71

Research Area: Physical Science

The terrestrial carbon pool, especially soils, have the potential to sequester large amounts of carbon by way of below ground carbon flux. However, the degree of carbon sequestration into soils is dependent upon the structure of the vegetation communities inhabiting them and the unique qualities of the soil itself. This study focuses on below ground carbon concentrations, specifically soil organic carbon (SOC), in relation to vegetation communities in the Chewaucan River Basin in southern Oregon. Over time, management practices within the Chewaucan site have resulted in major vegetation shifts, defined by woody Juniper encroachment, cheatgrass invasion, and dryland agriculture practices. To calculate SOC, cores from the top 10cm of soil were taken from different vegetation community plots across the site that included Juniper, Ponderosa Pine, sagebrush, Juniper/Pine, and alfalfa. Samples were dried to determine bulk density, texture, and Munsell color system rating. Soil sieving separated samples into coarse earth (>2.00mm) and fine earth fractions (< 2.00mm). A loss on ignition (LOI) test was completed on 5.00g fine earth from each sample to determine SOC values. Simple calculations show woody species (Ponderosa, and Juniper) plots having slightly elevated SOC concentrations than shallow rooted species (sagebrush, alfalfa). However, more complex analytical procedures will be completed using R statistical computing that account for multiple variables across all plots. This study has the potential to quantify SOC concentrations of soils that have not previously been analyzed. More importantly, this research could predict changes in SOC within rapidly changing ecosystems like the Chewaucan River Basin.

Search for Di-Higgs Resonance at the ATLAS Experiment

Presenter(s): Peace Kotamnives − Physics, Mathematics

Faculty Mentor(s): Eric Torrence

Poster 77

Research Area: Physical Science

Funding: Vice President for Research and Innovation (VPRI) Undergraduate Fellowship

With the question remaining whether there is only one Higgs boson or several, our research studies how a heavier Higgs boson could be found in the ATLAS data at the LHC. By the pure Standard Model phenomenon, we expect to find production of two SM Higgs bosons from the tri-linear Higgs coupling. However, the rate at which this will happen is far below what we will be able to see for many years at the LHC. As the discovered Higgs boson can decay to different pairs of particles, and the rate is expected to be proportional to the mass of the decay particle involved, the most likely decay channel is H→bb at 33%, and the second most likely channel is H→WW at 25%. Therefore, HH→bbbb channel has the highest rate of production, but HH→WWbb channel is chosen due to higher backgrounds in the four-b channel. In addition, two W bosons could decay into two quarks, one lepton and its neutrino. The performance of identifying HH→WWbb events for large heavy Higgs mass has studied specifically by using boosted object tagging. From the detector, we expect collimated jets from b quarks merging into a fat jet. By applying the relativistic kinematics theory and reducing some major backgrounds, we compare our alternative algorithms with the current algorithm in reconstructing the W→qq candidate. With the improved sensitivity, our expectation is to see a bump on top of the mass distribution indicating the new physics particle that we are searching for.

Asymmetry of the Dental Arcade in Six Populations from the Indian Sub-Continent 

Presenter(s): Aimee Herubin − Anthropology

Faculty Mentor(s): Jeanne McLaughlin, Frances White

Poster 76

Research Area: Physical science

Deviations from symmetry that arise during development are defined as fluctuating asymmetry (FA). Greater asymmetry is often related to differences in genetic and environmental factors experienced during development with males showing more asymmetry than females. We measured FA in human dental arcades from different Indian social castes. We hypothesized that men and women would have differing degrees of asymmetry as well as individuals in different castes. We measured samples from the John R. Lukacs Dental Cast Collection at the University of Oregon. Our sample consisted of 177 paired mandibles and maxillae (57 females, 120 males). Individuals were from one of six social castes. Permanent dentition was measured in a three-dimensional plane at the cervix between the first incisors and on the distal surface of premolars and molars. 13 landmarks were digitized using a microscribe-3DX© following the protocol of Frost et al (2003). Dental FA was measured by calculating the Procrustes’ distance between each individual and its mirror image. We compared mean asymmetry by sex and caste using a two-way ANOVA. We found significant differences in both the maxilla and mandible FA between castes (F=51.28, DF=5, p<0.0001 and F=19.40, DF=5, p<0.0001, respectively) but not between sexes with no significant interaction term. Our hypothesis that there would be a difference in asymmetry between sexes was not supported, however, our hypothesis that there would be differences in levels of asymmetry between castes was supported. This suggests that there may be genetic or environmental factors influencing dental arcade development differently in different castes.

Gait Stability Deficiencies In Veterans With Chronic mTBI

Presenter(s): Ravahn Enayati − Human Physiology

Faculty Mentor(s): Li-Shan Chou, Will Pitt

Poster 28

Research Area: Physical Science

While mTBI, or concussion, is typically associated with athletics, head trauma is widespread in the battlefield and combat training, as evidenced by 294,010 documented cases of mTBI in the Department of Defense between 2000 and 2016. It has been shown that veteran subjects with chronic mTBI continue to suffer from subjective symptoms. It is reasonable to believe they may also continue to exhibit impairment in their gait stability when tested under a dual-task condition. Eight veteran subjects diagnosed with chronic mTBI (1F; 32.3 6.5 years old) had their gait imbalance tested. Each subject walked barefoot in two conditions. The first condition involved each veteran providing their undivided attention toward their movements (single- task). The second condition had each subject concurrently completing a continuous auditory Stroop test, which consisted of the individual listening to different auditory stimuli and attempting to correctly identify the pitch (dual-task). A camera motion analysis system was used to collect imaging of each subject’s movements during both conditions. The results were then compared with those of an acutely concussed group of athletes which had a statistically significant gait deficit. The one-time test of the veteran group was compared with five different time points from the acute sample. The results found that in the dual-task condition, there was no statistically significant difference between the medial-lateral sway of the chronic veterans and the acutely concussed athletes. This indicates that the veterans that suffer from chronic mTBI suffer similar gait imbalance as the acutely concussed athletes.

Using Machine Learning for Source Detection at the First G-APD Cherenkov Telescope (FACT)

Presenter(s): Jacob Bieker – Physics, Computer and Information Science

Faculty Mentor(s): Tim Cohen

Poster 37

Oral Session 2S

Research Area: Physical Science

Funding: DAAD Research Internships in Science and Engineering (RISE)

Finding gamma-ray sources is of paramount importance for Imaging Air Cherenkov Telescopes (IACT). This study looks at using deep neural networks on data from the First G-APD Cherenkov Telescope (FACT) as a proof-of-concept of finding gamma-ray sources with deep learning for the upcoming Cherenkov Telescope Array (CTA). In this study, FACT’s individual photon level observation data from the last 5 years was used with convolutional neural networks to determine if one or more sources were present. The output from the neural networks were compared using the default method of finding sources as a baseline. The neural networks used various architectures to determine which architectures were most successful in finding sources. Neural networks offer a promising method for finding gamma-ray sources for IACTs. With further improvement and modifications, they offer a compelling method for source detection for the next generation of IACTs.

Using 3D Visualization to Study Immune Cell Distribution in Larval Zebrafish 

Presenter(s): Jacob Bieker – Physics, Computer and Information Science

Faculty Mentor(s): Raghu Parthasarathy

Poster 47

Research Area: Physical Science

Funding: Presidential Undergraduate Research Scholarship

Advances in microscopy and data visualization are enabling fundamental insights into a wide variety of biological processes. During the early development of zebrafish, a popular model organism, immune cells grow and migrate. How the distribution of immune cells in the organism changes with age, however, has been unclear. We therefore used light-sheet microscopy to image fluorescent neutrophils, a type of immune cell, in larval zebrafish during the first few days of the cells’ development. We then combined the imaging data with new three-dimensional visualization techniques using virtual reality to develop insights into the spatial organization of these cells. The virtual reality system is widely applicable and accessible, with the ability to run on common cell phones and work with various input types of input data. The use of virtual reality coupled with live imaging data shows the promise of three-dimensional visualization as an avenue for exploring biological data.