2013 Bruning Award Winner 

 

Modeling the Spread of White-Nose Syndrome in Hibernating North American Bat Populations
Sarah Bogen, Isaac Ressler
Mentor: Paula Federico
 


North American bat populations are currently being threatened by an emergent infectious fungal disease known as white-nose syndrome (WNS) which causes mass mortality in hibernating colonies. Since it was first detected in New York in 2006, WNS has spread rapidly in the United States and Canada and killed over 5.5 million bats. Control of WNS is of major concern to both the scientific and caving communities, and the disease and mechanisms of transmission are still not well understood. We developed an individual-based model at the county level to gain insight into the spatial and temporal spread of the disease. We assume the probability of infection for each county in a given year is a function of the density of caves, the estimated cave temperature, and relative proximity to other infected counties. Model parameters were estimated by means of maximum likelihood. We compared model predictions with known infection data from 2006 until 2011. The model imitates the overall spatial and temporal patterns of the data and may be improved by decreasing the number of “false alarm” predictions in future extensions of the study. 

 

 

2012 Bruning Award Winners 

  

Optimal Pricing Decisions for a Start-Up Company in the Car Rental Industry  

Alexander Maze
Mentor: M. Ali Ülkü
 

The car rental industry is worth more than $20 billion, accounting for 1.4% of the total GDP in the U.S., where car is the main mode of transportation. It is thus crucial to have a deeper look into the pricing decisions of the car-rental agencies (CRAs). This research aims to shed light on and to provide an analytical framework that can aid management of CRAs in making optimal pricing decisions while achieving the service expectations of the customers. Under the case of private information, and given the pricing scheme of the competitor, this research investigates and compares various multi-part pricing schemes, such as “fixed plus per-mileage,” to determine which one yields the maximum target profit for the sustainability of a start-up CRA. Regarding the value of transparency in service pricing to the customer, this research also studies the impact of the variability of probability distributions of mileage on the optimal prices and the resulting revenues. The determination of and the conditions under which a pricing scheme is superior to the others are attained by the theory of optimization and various operations management techniques.

  

 

The Hopelessness of Traditional Eschatological Hope: A Broken World’s Cry for Active Hope in Suffering
Sarah McIlvried
Mentors: Monica Mueller, Joy Schroeder
 


Eschatology, the study of the end of things, is often pointed to as the source of hope within the Christian faith. Such theology, which focuses on a new future without suffering, has sometimes been interpreted to ask humans to patiently endure their suffering and wait for it to pass, without providing anything substantial to help them cope. In the face of injustice this is often insufficient. Liberation Theology presents an alternative, more active, form of hope which exists in the midst of suffering and leads to change. I examine the movement of the Arpilleristas in Chile during the dictatorship of Pinochet to better understand how justice movements embrace a more active hope. By applying the beliefs of liberation theologians such as Dorothee Soelle, Jurgen Moltmann, and Vaclav Havel, I find that in a time when success seemed impossible and suffering dominated their lives, these women were able to cultivate hope through solidarity, a redefining of meaning in their lives, and action. For the sake of justice movements everywhere, such an understanding of hope is essential and must be adopted if we are to engage with this world rather than accept its injustices and suffering.

 

 

2011 Bruning Award Winner 

 

Microelectrode Arrays Formed via Reduction of Chromate Ion
Jamie Schwefel
Mentor: William J. Clark
 

 

Chromate ion (CrO42-) is used extensively as a corrosion inhibitor for many different applications. The mechanism of inhibition involves reduction to chromium [III] ion and strong attachment to the surface of the substrate. The layers formed are exceedingly thin, less than 10 nanometers, but the immobilized chromium [III] ion strongly resists electron transfer thereby inhibiting further electrochemical reactions. Using this property, a controlled deposition of chromate has been achieved on glassy carbon electrode material that partially inhibits the electrode surface by forming an incomplete barrier. As the surface coverage of chromium [III] increases, the remaining active areas of the electrode surface become smaller and more isolated from one another; beginning to behave as microelectrodes. These active areas ultimately form a random microelectrode array on the electrode surface and show altered voltammetric response towards model electrochemical systems as compared to a macroelectrode. Depending on experimental time scale, the array can exhibit semi-infinite linear or radial diffusion or a hybrid of the two. Conditions for optimal microelectrode array formation are presented including variations with chromate concentration, exposure time, and reducing potential. An assessment of electrode coverage and observations of microelectrode array behavior is shown.

 

 

2010 Bruning Award Winners 

 

Investigating the Molecular Basis of Temperature-Dependent Sex Determination in the Painted Turtle
Katherine L. O'Shaughnessy
Mentor: Nicole Valenzuela
 

 

Temperature dependent sex determination (TSD) is a commonly found mechanism in many reptilian species; however the molecular and evolutionary basis for this form of environmental sex determination remains unclear. This study used the painted turtle (Chrysemys picta) as a TSD model to analyze expression of two genes involved in vertebrate gonadogenesis, the Wilms’ tumor-suppressor gene (Wt1) and steroidogenic factor 1 (Sf1) respectively. Previous study observed differential expression of Sf1 and Wt1 in C. picta at constant temperature incubation. In order to mimic more ecologically relevant conditions this study compared expression of Sf1 and Wt1 under fluctuating incubation temperatures. The results obtained demonstrate significant differences in Wt1 and Sf1 expression; however, the timing of the differential expression is shifted to an earlier developmental period than under constant incubation conditions. These findings suggest that fluctuating incubation temperatures might affect the timing of the thermal sensitive period (TSP) and consequent activation of the genetic network responsible for sex determination in TSD species. This study was funded in part by the National Science Foundation (NSF IOS 0743284) and REU supplement IOS-0925486 to N. Valenzuela, and REU grant DBI-0552371 to M. Rothschild.

 

A Comparison of Design Modifications to a Novel Microbial Fuel Cell for Electrical Production and Bacterial Load Reduction
Rachel Yoho
Mentors: Patrick Shields, Jerry Thomas
 

 

The future of electrical production is one of the most pressing issues facing society. Microbial fuel cells have the potential to offset some of this problem through their ability to use many different materials to generate electrical power. Nine microbial fuel cells were constructed using different cathode materials and carbon cloth anodes for voltage production from a pig manure substrate. The open circuit voltage (OCV) of each of these cells was collected continuously, and the internal resistance (Rint) was measured at periodic intervals. From this information, the current (I) could be estimated. The change in the bacterial load of the manure in colony forming units per mL (CFU/mL) was also determined. Data collection on six of the cells was discontinued due to low voltage production. The remaining three cells (copper, brass, and carbon cloth) continuously generated an OCV for over eighteen weeks. Compared to the discontinued cells, the copper and brass cathode cells produced consistently higher voltages (approximately 0.65 V and 0.55 V) and had currents in the range of 15 to 25 mA and 8 to 10 mA, respectively, for the majority of their life spans. The carbon cloth cathode cell produced high voltages, approximately 0.68 V, but displayed a current of less than 10 mA. These three cells displayed an average bacterial load reduction of 93.6%. This information can be applied towards the development of more efficient microbial fuel cells with higher OCV and current outputs, and cells with increasing efficacy at reducing the bacterial load.

 

 

2009 Bruning Award Winner 

 

Structure and Function of a sno-like RNA in Haloferax volcanii
Julia Harris
Mentors: Jens Hemmingsen, Margaret E. Ginn-Pease
 

 

Small nucleolar RNA (snoRNA) is known to guide modification of RNA in eukaryotes and archaea. In this study, the structure and function of a conserved halophile sno-like RNA (sRNA) from the moderately halophilic archaeon, Haloferax volcanii (Hvo), has been characterized using genetic and biochemical methods. The sRNA is predicted to guide 2´-O- ribose methylation of cytidine-34 (C34) in elongator methionine tRNA (met tRNA). Northern analysis, RT-PCR walking and RT-PCR of cyclized sRNA show that the sRNA is likely to be cotranscibed with an adjoining gene and processed from a larger transcript. A mutant strain of Hvo. (sRNA) has been constructed in which the sRNA gene has been deleted. The mutant exhibits normal growth, indicating that this gene is not essential. An RNase H cleavage assay has been used to characterize the methylation of met tRNA isolated from wild-type and sRNA strains. Preliminary results suggest that the mutant may be lacking in methylation at C34. This work furthers our understanding of the mechanisms of tRNA maturation in the archaea.

 

 

2008 Bruning Award Winners 

 

Genetic Modification in Organics - Are the Labeling Laws Being Followed?
Claire Brandon
Mentor: Kerry L. Cheesman

 

The labeling of organic products in the U.S. can be confusing. Although there is an increasing demand for organic products, most consumers do not know what organic means or that there are laws governing the use of the organic label. By U.S. standards, a product labeled "100% organic" must contain only ingredients grown under standard conditions with no pesticides and no genetic modification (GM). Products labeled organic must contain at least 95% organic ingredients. "Made with organics" must contain 75-95% organic ingredients; less than 75% organic ingredients cannot use the word organic. So are the manufacturing companies following these important laws? This experiment was designed to determine whether soy and corn products labeled organic are truly organic and not genetically modified. Using standard techniques and materials from Bio-Rad Laboratories, DNA was extracted in duplicate from various store-bought foods, and amplified with PCR to detect the transgenic CaMV 35S promoter and/or NOS terminator sequences (found in approximately 85% of all GM foods). Samples were run on 3% agarose gels, with known GM-positive and negative controls, and visualized with UV light after staining with ethidium bromide. None of the corn products labeled organic (n=12), including corn meal and corn starch, were found to contain GM. Of the soy products labeled organic (n=11), only one (8%) was positive for GM. Analysis of corn and soy products with no indication of GM content on the label revealed a 70% rate (n=18) of GM. It appears from these data that in nearly all cases U.S. manufacturers are indeed following the law, and American consumers can be confident in purchasing organic corn and soy products.

 

Identification of a sno-like RNA in Haloferax volcanii
Meghan B. Williams
Mentors: Jens Hemmingsen, Margaret E. Ginn-Pease

 

A putative sno-like RNA (sRNA) has been identified and characterized in Haloferax volcanii (Hvo), a moderately halophilic archaea. Based on its sequence characteristics and the mechanism of snoRNA-mediated modifications, this sRNA would target 2’-O-ribose methylation of cytidine-34 in Hvo methionine tRNA. Bioinformatics studies have identified that this sequence motif is present in all known halophilic archaea. RT-PCR and Northern blot analysis have detected expression of the sRNA with a length of 120 nucleotides. RT-PCR results also show that the sRNA is initially transcribed as part of the 3’ untranslated region of a mRNA and is subsequently processed. A mutant strain of Hvo lacking the sRNA gene exhibits normal growth indicating that the sRNA-mediated modification is not essential for viability. This study advances understanding of RNA processing in archaea. 

 

 

2007 Bruning Award Winner 

 

A Model for the Prediction of Substrate Use during Exercise
Tayler A. Blake
Mentors: Catherine Boulant, John Phillips, Edward Lipinsky


Energy for endurance exercise is primarily derived from carbohydrate (CHO) and fat. The relative contribution of substrates is affected by a number of variables including the following: exercise intensity, exercise duration, diet, and training status. During steady state exercise, respiratory exchange ratio (R) is a reliable predictor of relative substrate contribution. The present model was developed to predict percent contribution of substrates during steady state exercise. Input variables include exercise duration and intensity (as a percentage of maximal aerobic capacity), and the fitness level of the individual (on self-rated, 5 point scale). The model assumes a mixed diet of 60%:15%:25% :: CHO: protein: fat. The model system is simulated using STELLA®, a dynamic mathematical modeling software that represents inputs and outputs graphically. This tool is especially useful for simulating systems over time. The model uses a diagram of stocks and flows which is supported by the language of STELLA® to simulate the system. Stocks and flows were enumerated using values obtained from published exercise research. The results include graphs and tables plotting predicted R and predicted percentages of CHO and fat utilized as substrate during the exercise bout. Outputs were then compared to values obtained from different published exercise data. Continued development of the model may include changing nutritional status from a mixed diet to a high fat or high CHO diet.