MY RESEARCH

During the summer of 2019, I was a faculty mentor of the interdisciplinary Collaborative Summer Research Experience (CSRE) at Fitchburg State University. The project consists of sub-groups from different scientific disciplines working together to analyze the health of the Nashua River watershed. I led an undergraduate mathematical modeling sub-team consisting of myself and two rising senior undergraduate mathematics majors. We obtained water testing data for E. coli and conductivity in our region from the Nashua River Watershed Association and conducted a spatial modeling study of contaminants in the Nashua River watershed using Maximum Entropy Modeling (Maxent). Over a nine week period we conducted a full literature review, gathered dozens of potential predictor variables in the form of GIS raster maps, and analyzed dozens of Maxent models. We ultimately settled on four models for conductivity levels in the region and four models for levels of E. coli in the region (see image 1 below)...

This project was conducted in the summer of 2018 with a senior mathematics major. This work was recently submitted for publication.

Overview

               Diamondback terrapins (Malaclemys terrapin) live in estuarine habitats along the Atlantic and Gulf coasts of the United States. Populations in many locations are declining due to increased nest destruction and drowning in crab traps. Using data collected by collaborator Dr. John Ludlam, we developed three models to evaluate these threats and consider the conditions needed for terrapins in South Carolina to persist. 

               We first developed a matrix model that includes both sexes with age classes partitioned by size since smaller terrapins, especially males, perish in crab traps at a higher rate. This can lead to the sex-ratio of the population becoming skewed towards females. By adjusting the class-specific survival rates in the two-sex model to reproduce collected data, we use the...

Pseudorabies is a herpesvirus that is relatively harmless to hogs but is deadly to a number of other wild and domestic animals. Since it lowers the birthrate and infant survival of domestic swine, the USDA has worked hard to eliminate the disease from the domestic swine industry. Wild hogs are the largest reservoir for pseudorabies in the United States, and its prevalence in GSMNP has been increasing since 2005.

After considering recent results related to pseudorabies in feral hogs, I built a compartmental disease model into the metapopulation model to analyze the spread of the disease in wild hogs in the Park. This involved considering various potential transmission routes and fitting parameters to available data. Results provide evidence that more than one transmission route exists for pseudorabies in wild hog populations. 

FULL PUBLICATION HERE

The Ebola Virus Disease (EVD) poses a significant threat to the human race. The resurgence of this highly infectious disease in 2014 produced over four times as many deaths as all previous outbreaks combined. Even more concerning, the threat is no longer isolated in Africa because modern travel has connected the world in ways that allow the deadly disease to jump across continents in a single flight. I have obtained data related to the outbreak in the three countries most affected by the recent outbreak of EVD: Guinea, Sierra Leone, and Liberia.

The data was was collected at the region level and include percent of population living in an urban area, density, average level of education and many more. These variables will be related to the total confirmed cases of ebola in each region using statistical modeling techniques.

This work is in collaboration with Dr. Agricola Odoi of the University of Tennessee. We initially tried using a poisson model before...

FULL PUBLICATION HERE

 

 

                     Since a considerable amount of time and money are spent on the control program, officials have a vested interest in efficiently removing hogs from GSMNP. I assisted in this effort by using removal locations to develop a spatial model for the population's niche. The form of the harvest data lends itself to a presence-only distribution modeling method such as an environmental niche factor analysis (ENFA). This approach uses the concepts of marginality and specialization to quantify a species’ niche by relating ecogeographic data to known presence locations. Marginality determines the types of conditions the species prefers and specialization measures how much the species deviates from their preferences.

 

 

                     In order to measure these correlated and multi-variable dependent values, ENFA leverages the theory of principal component analy...

          FULL PUBLICATION HERE

 

 

                  I used a discrete metapopulation model to evaluate the importance of the Park’s control program, estimate key population parameters, and to gauge the size of the population in the Park. Vegetation data was used to partition GSMNP into eight regions based on overstory type. To match Park policy, harvesting is modeled on a seasonal basis in which more hogs are removed during the winter months. The primary food source for feral hogs is acorns, the abundance of which significantly influences survival, birth, and movement rates of the population. To model this relationship, mast-dependent parameters vary at each time step. The model accounts for the influence of spatial variation in GSMNP by implementing a seasonal movement pattern and integrating vegetation data with yearly mast data.      

 

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                FULL PUBLICATION HERE

During the summer of 2015, I mentored a group of undergraduate researchers at the National Institute for Mathematical and Biological Synthesis (NIMBioS) at the University of Tennessee. We studied canine distemper virus (CDV), which is a highly infectious disease that affects a variety of animals. Common symptoms in canines include sinus discharge, gastrointestinal unrest, and neurological ailments, often resulting in death.

             A vaccine for the disease was developed for domestic dogs in the 1950s and resulted in near elimination of CDV from pets in the United States. However, wild animals remain a reservoir for the disease and a lapse in vaccinations lead to several recent outbreaks of CDV in animal shelters in Tennessee. The local resurgence of CDV inspired work between mathematicians and veterinarians to create a compartmental model with ordinary differential equations (ODEs) for the disease in a general...

FULL PUBLICATION HERE 

The 2014 EVD outbreak reached unprecedented levels in part due to the general public in affected countries being uninformed about the disease. As a result, a large portion of the population did not take necessary precautions to avoid infection and many infected individuals did not seek medical treatment in a timely manner. This behavior exacerbated the spread of the disease because when a highly infectious individual refuses medical treatment, they expose additional uninformed community members, which has a compounding eff ect. These dynamics are what lead researchers to predict that over 1.4 million cases of EVD would occur by mid-January 2015. However, a massive international e ort began in September 2014 that largely focused on educating the general public about key aspects of EVD transmission. This immense response can be credited with limiting new EVD cases and highlights how education and resulting behavior change can have a profound impact on a disease epid...

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© 2015 by Benjamin Levy

 

Fitchburg State University

National Institute for Mathematical and Biological Synthesis