Characterization of the Role of CG12479 in
Drosophila melanogaster Mitochondrial Morphogensis
Rosalind Spell and Bradley G. Johnson
Legacy of Intensive Agriculture:
The Timing and Cause of Gully Formation in the Davidson Area
Gullies are common geomorphological features in the Piedmont of North Carolina that leave evidence of their erosion and deposition in the form of alluvial fans and gully fill sediment. We hypothesize that the formation of gullies in the Davidson area can be tied to intensive land use in the early years of Euromerican settlement in Mecklenburg County. Methods of investigation included digital and field mapping of gullies, soil pit observation, loss on ignition and particle size analysis, and radiocarbon dating. Results show that soils in gullies or their alluvial fans are less developed than the typical soil of the region and show evidence of erosion. Radiocarbon data link sedimentary deposition in alluvial fans and gully fill to the 18th century, which is concurrent with early Euromerican settlements in the Davidson area. This study concludes that land-use practices utilized by Euromericans had a detrimental erosive effect on Piedmont soils.
Hannah Thigpen
Determining Distances to Galactic Molecular Clouds
Molecular clouds in our Galaxy act as nurseries for star formation and are also important for other observed physical phenomena. It is a vital pursuit in astrophysics to locate these galactic molecular clouds to obtain a full understanding of the galaxy in which we live. In this poster, I present a spectroscopic method for calculating clouds’ radial velocities; by the application of the velocities to a galactic rotation curve model, we may determine the distance of the molecular clouds from our Sun. We determined radial velocities of molecular clouds by performing multicomponent Gaussian fits to the 1667 MHz OH ground-state absorption lines observed with the Arecibo telescope. By comparing these velocities to the known Galactic rotation curve, galacto- and heliocentric distances were determined to the molecular clouds.
Annalee Tutterow and Kevin Smith
Rarity, richness, and randomness:
assessing the sampling effect of biodiversity at the local scale
The presence of rare and endemic species is often used to identify areas of conservation priority. However, it is unclear if rare species diversity varies independently of overall species richness or if it is instead an artifact of a sampling effect of biodiversity. We created a null model to test whether, through a random sampling effect, the presence of locally rare species is primarily a function of overall species richness. We conducted a thorough literature review for biodiversity datasets from various taxa occupying environmentally-bound sites (e.g., ponds and islands) and defined rare species as those occurring at 10% or fewer sites in a dataset. To develop the null model, we used a 2×2 swapping algorithm that simulated random combinations of species at different sites, with fixed species occupancy and local richness. In other words, each site retained the same number of species and each species occupied the same number of sites in the simulations. Our simulation results showed a strong, positive curvilinear relationship between total species richness and the number of expected rare species. Across all sites, expected rare species richness from the simulation analysis was a remarkably strong predictor of the observed number of rare species per site (R²=0.92; p<0.001), providing strong support for the sampling effect of biodiversity in determining the number of rare species per site. Within individual systems, however, our results were more variable, including cases of strong (gastropods: R² = 0.99) and weak relationships (aquatic invertebrates: R² = 0.094) between expected and observed rarity values for certain taxa. Ultimately, our study suggests that at a local level, management efforts directed towards habitats with high species richness are also likely to capture large proportions of rare species of high conservation concern and provides additional evidence for the sampling effect of biodiversity.
Yufei Wang and D.R. Striplin
Computational Study of Excited States of Luminescent Bimetallic 1,1-Bis(diphenylphosphino)methane complexes
Many bimetallic complexes with bridging phosphorus ligands have a unique luminescence in that they both phosphoresce and fluoresce. The low lying phosphoresce denotes a transition from what is formally three degenerate excited states, a triplet state. In reality the three states are not iso-energetic but split into what is believed to be one lower state and two upper states separated by 10’s of cm-1 in energy, a splitting that occurs because of relativistic spin-orbit coupling (SOC). What was once a prohibitive computation, quantum mechanically, because of computation limitations should now be possible for these large heavy metal complexes. The bimetallic complexes [Pt2(pop)4]4-, [Pt(CN)2Rh(tBuNC)2(µ-dppm)2][PF6], Pt2(CN)4(µ-dppm)2, [AuIrCl(CO)(µ-dppm)2][PF6], [AuPt(CN)2(µ-dppm)2][PF6], [AuRh(tBuNC)2(µ-dppm)2][PF6]2, where dppm = (diphenylphosphino)methane; tBuNC = terr-butyl isocyanide; pop= pyrophosphate were studied computationally utilizing density functional theory (DFT) to compute molecular orbitals and excited state energies utilizing open shell computations, B3lyp functionals, a SDD pseudopotential for the metals, and a 6-31G(d) basis set for all other atoms. Computational results showed that lowest energy excited state transition in these complexes originate from a metal-metal anti-bonding dz2 highest occupied molecular orbital (HOMO) and a metal-metal bonding pz lowest unoccupied molecular orbital (LUMO). The results are consistent with the systems ability to both fluorescence and phosphorescence because both orbitals have zero angular momentum and will not couple well with higher lying singlet states. Using the excited state energies and transitions from the computations, SOC perturbations was applied to estimate the energy splitting of the lowest triplet state and the results compared to experimental work.
Caleb Warren
Predicting Parent Elements in Radioactive Decay
Research with radioactive samples often requires taking its spectrum and determining what elements are within a sample. This project aims to ease that process by creating a program to read data from a spectrum and present an ordered list of likely radioactive elements in this spectrum. This is done by comparing NNDC’s database of elemental data to intensity peaks in this sample and reporting those intensities who are most common between the two systems.
Erin Xu, Anthony Ciancone, Kaley Gonzalez, and Prof. Nicole Snyder
Synthesis of linear and branched glycomacromolecules targeting CD44
The affinity between hyaluronic acid (HA) and CD44, a protein overexpressed on the surface of many tumor cells, offers promise for delivering HA-based therapeutics conjugates to tumors. In principle, HA-therapeutic conjugates can selectively target tumor cells, increase the solubility of the therapeutic, and aid in its passage through the blood-brain barrier via receptor mediated endocytosis, thus improving pharmacological uptake. We are particularly interested in HA-phototherapeutics for photodyamic and photothermal therapy due to the less invasive nature of these techniques. One of the main limitations of this work is the synthesis of hyaluronic acid analogs that maximize the HA-CD44 interaction. In this session we present our progress on the synthesis of a series of HA-based mimetics of different lengths and their conjugation to phototherapeutics.
Alec Custer
“add / drop / swap”:
Developing Privacy and Trust in a Web Application
for Trading Courses at Davidson College
A number of recently popular online platforms, such as Uber, Airbnb, and Tinder facilitate complex and potentially dangerous interactions between users. For users to feel confident entering these communications, software developers must carefully engineer trust both in other users and in the platform itself. This thesis in Digital Studies introduces Swaptime, an open-source web application that helps Davidson students secure seats in high-demand courses by organizing trades with their peers. Swaptime also asks its users to navigate potentially risky transactions, but unlike Uber and similar platforms that coordinate non-repeating interactions between complete strangers, Swaptime targets a student body that prizes accountability and trust between its members. This distinction enables Swaptime as a lens for exploring the challenges involved in preserving an offline community’s values and cohesion in a new online space. By applying prior research on security, trust, and identity online to the advent of single sign-on services (SSOs), this project theorizes that developers can utilize SSO logins to “embed” trust into community technologies.