The USDA defines a food desert as any census tract where at least 20% of the residents earn below the poverty line and at least 33% of the residents live more than one mile (urban locations) or ten miles (rural locations) from a supermarket selling fresh groceries. The presence of a food desert has been correlated with negative health outcomes in obesity, diabetes, and heart disease. The Healthy Food Financing Initiative launched in 2010 hoped to eliminate food deserts by 2016, but this result has yet to be seen in communities across America. However, since 2010 the geographical location and density of food deserts has shifted. It is unknown whether this shift is due to government intervention or demographic changes. Likewise, the census tracts where food deserts have appeared or disappeared have yet to be characterized. This study utilized data from the USDA, US census, and American Community Survey to identify how demographic changes and government spending is related to food desert movement between 2010 and 2015. This data was also used to characterize individual census tracts for poverty, SNAP enrollment, and other factors that may explain food desert movement. A regression analysis produced a more complete explanation of this phenomenon through an empirical and quantitative examination of the relationship between these metrics. Ultimately, this geographical and statistical study will serve as both a policy and a demographic analysis that explains trends in recent food desert movement. Researchers and policymakers can expand upon the conclusions of this study to create more targeted, effective, and efficient programming that improves food access across the United States.

The goal of this project is to design a faster and more efficient motion controller for the leaf collimator that is used to shape a neutron beam around a tumor for use in intensity modulated neutron radiation therapy. The system currently in operation was developed in the 80’s and is too slow for new treatment techniques we plan to support. We started with familiarizing ourselves with the Galil motion controller and the Experimental Physics and Industrial Control System (EPICS) software to control 40 motors that will adjust the position of the collimator leaves within an accuracy of 2 mm. Because we augmented an existing system, there are some system aspects that could not change and needed to be worked into our design: the 40 motors need to be driven manually with analog feedback and the overall mechanical setup should remain mostly the same. Additionally, we rewired the system to accommodate bipolar power supplies in order to half the number of wires used in the gantry, allowing us to save on space and increase the ease of future system maintenance. This was accomplished by configuring diodes in parallel with relays that allows us to control the direction of the current, which in turn controls the rotation of the motors. Since our system’s internal components are heavily exposed to radiation, we implemented the diodes on a printed circuit board to ensure that the system upkeep and component replacement is manageable. Finally, we updated the existing Extensible Display Manager (EDM) user interface so the radiation therapists and technicians can see real-time leaf locations and interact with our motion control system. The final deliverable is a complete installation of our new fully tested system inside the the gantry.

Our goal is to create an inverted pendulum in the form of a cube. An inverted pendulum is an object with a center of mass above its pivot point. Having the center of mass above the pivot point makes for an unstable system. The object will tend to fall over when it is not perfectly balanced, or when no external force is applied. To balance the object and keep it stable, a controlled counter force must be applied. Generating the counter force for our cube will be accomplished by using angular momentum. Controlling the angular momentum will be achieved through counter-torque generated by the three internal motors, each spinning on an axis perpendicular to the others. These motors will spin flywheels in order to store angular momentum. The stored angular momentum can be utilized by controlling the torque and direction of the motors. This will ultimately cause a net force to be applied to the cube in a direction determined by the sensor feedback and control algorithm. This project has its significance in the field of aerospace. For instance, having an object fixed in a certain angular position in the outer space. Moreover, the control system, which takes input of gyroscopes and accelerometers to control flywheels and motors, has various applications in the field of automobiles and construction machinery.