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Math professor making big impact as researcher, mentor

Hristo Kojouharov
Hristo Kojouharov came to UT Arlington in 2000 and has taken on a leadership role in the Department of Mathematics.

When Bulgarian native Hristo Kojouharov came to the University of Wyoming to study for his doctoral degree in 1995, he knew very little English. It’s a pretty safe bet no one in Laramie knew any Bulgarian, either.

He found Wyoming wasn’t too much like what he had read and heard about the United States. Plus, he arrived in January, in the midst of a brutally cold winter.

While the language barrier was a challenge at first, Kojouharov’s studies were in a universal language - mathematics.

“Luckily, the language of mathematics is the same everywhere, so I could read numbers, mathematical notation, theorems and algorithms, which allowed me to not fall behind in my studies,” he said. “Plus, being the only person in Laramie speaking Bulgarian turned out to also have a positive effect on me, as it left me with no choice but to learn English as fast as I could and to adapt to the local culture.”

After receiving his Ph.D. in Applied Mathematics in 1998, he set about fulfilling the goal he had made for himself in high school - becoming a math professor at a research university. In 2000, Kojouharov joined the faculty of the Department of Mathematics at UT Arlington, where he is heavily involved in outreach and mentoring students in addition to his research and teaching.

“I enjoy teaching and doing research in mathematics at the university level - now that I have several years’ experience with that, I am totally convinced that I made the right choice,” he said. “I also very much enjoy mentoring students, both at the undergraduate and graduate level.”

Said Jianping Zhu, chair of the Department of Mathematics, “He is a great asset to the department. He is doing interesting research in mathematical biology and numerical analysis, and he is a popular teacher who attracts both undergraduate and graduate students.”

Kojouharov, who lives in Mansfield with his wife, Daniela, and young sons, Velin and Martin, has taken on a leadership role in the department in research, outreach and in mentoring students. His passion for research and for helping his students is obvious to his colleagues.

“I can say that he is one of the most dedicated educators I know anywhere,” said biology professor James Grover, who often collaborates with Kojouharov. “He is deeply concerned about all the students he teaches, from those who take a single undergraduate class to the graduate students he has mentored.”

Added math professor Benito Chen Charpentier, “Hristo is a man of many qualities. I am always impressed by his willingness to help and to take leadership roles. Whether it is helping a student or doing committee work or even giving a ride to the airport, he is always there with a smile. Collaborating with him is always a pleasure because of the knowledge, time and effort that he puts into writing a paper or a grant proposal.”

Kojouharov’s main research interests are in numerical analysis and mathematical biology. His work is motivated by practical applications, and he is interested in mathematical modeling and theoretical analysis of biological phenomena, as well as in developing accurate, efficient numerical methods for solving mathematical models that preserve vital characteristics of the biological system.

“I like the fact that my mathematics research can be applied to practical situations and that it can have positive effects on various aspects of life,” he said. “I enjoy very much collaborating with other people and working in a team environment. Doing research in applied mathematics at the interface of mathematics and biology, bioengineering, and other sciences provides me with the perfect opportunity to work with other scientists and engineers, exchange research ideas, and discuss and advance joint research projects.”

Kojouharov’s research projects have ranged from modeling the spread of bovine tuberculosis in African buffalo to modeling the colonization resistance of resident microflora in the mammalian gut to modeling the formation and persistence of multi-species biobarriers that restrict the flow of pollutants in contaminated groundwater systems.

One of his current projects, in collaboration with Chen Charpentier and professor of bioengineering Liping Tang, is aimed at developing new discrete, hybrid, and continuous mathematical models of the complex interaction between bacteria and white blood cells on biomedical implants pre-coated with different proteins. On the numerical analysis side, the goal is to develop a new class of nonstandard finite-difference models for the aforementioned mathematical models that preserve the essential properties of the corresponding biomedical system.

The knowledge gained from this research, Kojouharov said, could be used to determine the types of implant protein coatings that will improve the body’s defense against bacterial infections while simultaneously decreasing adverse foreign body reactions. This could minimize the risk of serious infections, the cost of medical treatments, and help design safer medical implants.

“Professor Kojouharov is a bright, hard-working and very productive mathematician with great interest in biomedical problems,” Tang said. “Since the beginning of our collaboration about one year ago, he and his student have made great progress on the topic issue, with one pending manuscript and one proposed grant application.”

Another of his projects is being done with math professor Jianzhong Su, Tang and visiting professor Michail Todorov.

“Recently, I have started a very pleasant and productive collaboration with Hristo in developing mathematical models for inflammatory reactions, which is related to human responses to medical implantation,” Su said. “The new mathematical method can be either a traditional continuum differential equation model or multi-scale model involving continuum equations and discrete cells. I expect we can find many useful applications for the method, and our collaborations will continue for many years to come.”

Kojouharov was born in Razgrad, Bulgaria. He enjoyed and excelled in math from a young age and regularly attended regional and national math competitions, beginning in fourth grade. After high school, he went on to Sofia University in Sofia, Bulgaria, where he received a combined bachelor’s and master’s degree in Mathematics in 1994. A sense of adventure and a desire for greater opportunities led him to come to the United States for his doctoral work, and he received a full graduate research scholarship to the University of Wyoming. A semester later, his wife joined him from Bulgaria, also on a full graduate research scholarship, to work toward a Ph.D. in Statistics.

After earning his Ph.D., he spent two years at Arizona State University as a visiting assistant professor, and then came to UT Arlington, where he has sought ways to collaborate with peers from both inside and outside the math department.

In 2008, he was the principal investigator in securing a five-year, $780,946 grant from the National Science Foundation for creation of the Undergraduate Training in Theoretical Ecology Research (UTTER) program, which provides an integrated research and educational experience for cohorts of biology and mathematics undergraduates.

Each cohort of eight students pursues a two-year program of mentoring, seminars, research, and interdisciplinary coursework. The program also facilitates transition into graduate studies and other interdisciplinary careers through extensive faculty and peer mentoring as well as guidance in pursuing graduate studies.

As director of the UTTER program, Kojouharov leads a faculty team which includes Grover (co-director), Chen Charpentier, Laura Gough, Doyle Hawkins, Christopher Kribs Zaleta and Laura Mydlarz, and graduate students Alicia Prieto Langarica and Betty Scarbrough, who serve as teaching/research assistants.

“At this point in the UTTER program, we have successfully recruited the first two diverse cohorts of undergraduate students,” Kojouharov said. “Curriculum and the new courses have been developed and well-received by the students, and have been incorporated in a Mathematical Biology option for the Mathematics B.S. degree at UT Arlington. The student research projects are now being developed into conference presentations and draft publications. Some of the members of the first cohort are nearing graduation, and all of them have expressed an interest in graduate studies.”

With UTTER, Kojouharov is in charge of project management, coordinating student recruitment and selection and, with Grover, co-teaching courses and the five-week intensive summer research workshop.

“I've been on several doctoral committees with him, and we co-teach two [UTTER] courses. I've seen the personal commitment he makes to his teaching and his interactions with students, and I'm always impressed by it,” Grover said.

Kojouharov was also the co-PI for a four-year, $483,000 NSF grant to support the Scholarships for Undergraduates to Reach Goals in Education (SURGE) program, which is designed to enhance undergraduate education in mathematics. SURGE provides students in financial need with scholarships and strong mentoring support to ensure that they receive degrees in a timely manner, and that they are well-prepared to enter the workforce or to continue advanced graduate studies.

In addition, he serves as faculty advisor of the student chapter of the Mathematical Association of America (MAA) at UT Arlington. The MAA’s goal is to promote unity among members, stimulate interest in a variety of mathematical subjects, and promote and encourage the study of mathematical sciences.

Kojouharov also created the UT Arlington Calculus Bowl, a community outreach program aimed at area high school students. The annual event is a contest in which teams of students compete to answer challenging pre-calculus and calculus questions to earn points, with the top teams receiving awards. The event, held on campus, is a superb recruiting tool for the department; last year, a record 28 teams competed. The 11th annual Calculus Bowl is scheduled for Feb. 4.

“The main goal of the Calculus Bowl is to provide an atmosphere in which interest in mathematics is stimulated among high school students and to recognize those who exhibit exceptional talent regardless of socioeconomic status,” Kojouharov said. “I like to see the students excited about mathematics. It is a way for me to give back to the community, to show students that math can be fun and interesting.”

His work has led to accolades from colleagues and University administration. He has received five Travel/Professional Development Awards and three Research Excellence Awards from the UT Arlington provost’s office in the past five years, and was named Professor of the Year by the MAA UT Arlington chapter in 2005.

He has also found time to serve as mentor to five master’s and five doctoral students since 2003, and says their accomplishments are among the most rewarding parts of his career. Having achieved his goal of becoming a math professor at a major research university, Kojouharov is now intent on helping others attain their dreams.

“I enjoy mentoring students and helping them, so they can have a positive influence on other students once they become teachers and researchers,” he said. “It is a very good feeling to see others get better because of something that you did.”