Dr. Frauke Tillmans

Vice President of Research

Dr. Tillmans holds a degree in Neuroscience, and a Ph.D. in Human Biology from the University of Ulm, Germany. She oversees research initiatives in diving injury and fatality monitoring, population health, and diving physiology including acute diving injuries as well as long-term health effects of extreme exposures. She is an avid diver, dive safety officer, and dive instructor. Her experience spans recreational, technical, rebreather, scientific, and public safety diving. Throughout her scientific career she has participated in numerous projects covering a variety of medical aspects in recreational, professional, and military diving. Since leaving a position at the German Naval Medical Institute in 2019 to relocate to the United States, she has become DAN’s point of contact for global scientific collaborations and is in charge of DAN’s research grant program and STEM-focused internship program, inspiring young scientists and prospective physicians to pursue a career in diving and hyperbaric medicine. Dr. Tillmans is also an adjunct assistant professor in the Department of Biomedical Engineering at the University of North Carolina at Chapel Hill and a visiting scientist at the University of California, San Diego.

Dr. Ted Bateman

Senior Researcher

Dr. Bateman spent a summer at Kennedy Space Center as an undergraduate (Bachelor of Science in Physics, DePauw University) and from there decided he needed to become an engineer. He went on to earn an MS in Solid Mechanics/Civil Engineering (Colorado State) with a thesis on FE analysis of inflatable structures for the moon and Mars. He then earned a Ph.D. (Bio/Aerospace Engineering) and post-doc at CU Boulder, where he got to fly mice and rats in space, examining changes in skeletal biomechanics with cytokine therapies. He then went on to be a professor for 20 years. He first taught at Clemson University and then at the University of North Carolina at Chapel Hill, in Biomedical Engineering, where his lab continued to participate in Space Shuttle experiments, making new discoveries including the effects of space radiation on bone loss.Dr. Bateman is excited to start a new chapter in his career at DAN as a Senior Researcher where he is building a team to posit a structural analysis approach to dysbaric osteonecrosis. As NASA transitions from ISS (research laboratory) to lunar exploration missions, there will be exponentially more space walks (EVAs). This adds DCS to the existing biomedical risks of reduced gravity and space radiation. He hopes to slowly convince the Space Biology society that he grew up in to add DCS to their basic science portfolio, particularly in the context of greater space radiation on the moon.

Dr. Emmanuel Dugrenot

Senior Researcher

After completing a master’s degree in molecular biology, Dr. Dugrenot worked as a dive instructor, specializing in technical and rebreather diving and earning an instructor trainer certification. Around that time, he also created and ran a company to develop improved decompression procedures, collaborating with engineers, mathematicians, and biologists. After several years working full time in the dive industry, Dr. Dugrenot completed a Ph.D. in Physiology at the University of Western Brittany (France) on genetic resistance to decompression sickness. It was only natural that he joined DAN in November 2022 to continue working on divers’ safety.

Dr. Dugrenot is also a visiting researcher in the Department of Biomedical Engineering at the University of North Carolina at Chapel Hill and at the ORPHY laboratory at the University of Western Brittany. His research interests include Hypobaric Decompression Sickness (DCS) in space walks, and his work is supported by external funding sources such as the Office of Naval Research (ONR).

Christi Opresko

DoW SkillBridge Visiting Scientist

Christi Opresko is a Lieutenant Colonel in the United States Air Force working at DAN through the Department of War SkillBridge Program. She earned a bachelor’s degree in Exercise Science from the University of Georgia and a master’s degree in Health Promotion with a Sports Performance Emphasis from Virginia Polytechnic and State University. She is a senior Aerospace Physiologist with over 20 years of experience in aircrew training, aviation safety, human factors, and Air Force Operations Policy. Prior to participating in the DOW SkillBridge Program, Christi was the Aerospace Physiology Senior Research Advisor in the Air and Space Biosciences Division at the Air Force Research Laboratory located at Wright-Patterson Air Force Base near Dayton, Ohio.

Alannah Johnson

Research Grant Manager

Alannah Johnson is a Research Grant Administrator at DAN, where she advances the organization’s mission by coordinating funding opportunities and managing grant projects that promote diver health and safety. She holds a bachelor’s degree in Biology from the University of Alaska Southeast and a Master of Science in Biomimicry from Arizona State University. A certified recreational scuba diver, Alannah blends her passion for tropical diving with expertise in grant writing, management, and project oversight. Her entrepreneurial experience includes owning and operating a commercial mushroom farm in Southeast Alaska, where she secured funding to combat regional food insecurity and was selected by the Biomimicry Institute’s Launch Pad program for her innovative work reimagining health care systems modeled on fungal networks. Building on these diverse experiences, she is now preparing for medical school, reflecting her ongoing commitment to health and the well-being of the diving community.

Tyler Horton

Research Associate – Medical Research

Tyler Horton is a native of Indiana and a graduate of the University of Dayton, where she earned a Bachelor of Science in Biology with minors in Neuroscience and Spanish. After graduation, she worked as the Executive Director of an international public health nonprofit focused on bridging gaps in cancer care. Her work spanned from Cali, Colombia, where programming focused on the early screening, preventive care, and patient navigation of breast and cervical cancer, to across North America, where initiatives focused on awareness, patient navigation, and a resource network for individuals affected by advanced gastrointestinal and gynecologic cancers.

Tyler then spent a year solo backpacking around the world. Along the way, she fell in love with scuba diving, discovered the field of dive science, and has not stopped diving since. Dive physiology proved to be a beautiful intersection of her passions for human physiology, global health, and safety. This inspired her to apply for the DAN Research internship, which she completed in summer 2025. Tyler is now working as a DAN Research Associate focused on dive physiology projects and has special interests in continuing her education in extreme environment physiology and public health.

Olivia Jackson

Research Associate – Medical Research

Olivia Jackson is a Research Associate II whose work has focused on health and performance in extreme environments since 2018. Her research experience spans diverse populations, including astronauts, aviation pilots, warfighters, divers, and marine mammals. She holds a strong interest in neuroscience and has developed a particular focus on diving physiology and safety, with the goal of advancing evidence-based practices that improve diver health and performance. Olivia recently completed her master’s degree at the University of North Carolina Wilmington. Funded by the Office of Naval Research (ONR), her graduate research focused on characterizing the brain lymphatic system in marine mammals, with an emphasis on implications for health and diving performance. This work strengthened her interdisciplinary approach to studying health and safety in extreme environments.

Although she grew up along Florida’s panhandle and loved the water, Olivia was scared of diving. However, through research exposure and the support of experienced mentors and peers, hesitation evolved into confidence and a strong sense of belonging underwater. Today, diving is central to both her research and professional identity. Outside of research, Olivia is passionate about education, safety, and science communication, and is driven to translate rigorous science into accessible knowledge for both scientific and public audiences.

Zainab Manzoor

Research Associate – Injury Monitoring

Zainab Manzoor is a novice scuba diver who began her diving journey in 2024. She has quickly realized that she was very spoiled by getting certified during her Master of Public Health (MPH) internship in Suva, Fiji. Originally from Wisconsin, Zainab grew up near Lake Michigan and spent countless hours in or by the water while studying at the University of Wisconsin–Madison, earning her Bachelor of Science in International Studies and Global Health in 2021. She then moved to Indianapolis to work on fatal and non-fatal opioid overdoses with the Centers for Disease Control and Prevention (CDC) at the Marion County Public Health Department. During her time at the CDC, Zainab discovered her passion for injury epidemiology and left in 2023 to pursue an MPH in Global Health Epidemiology, specializing in Injury Sciences at the University of Michigan–Ann Arbor, and graduated in 2025. Zainab’s experience in injury prevention has focused on unique and vulnerable populations, including people with substance use disorders, domestic violence survivors. Zainab is excited to grow as a diver with DAN’s research team while applying her injury epidemiology expertise to identify patterns in dive-related injuries and fatalities, helping improve dive safety and advancing DAN’s mission to make diving safer for everyone.

Raana Zakeri

Graduate Research Assistant – Epidemiology

Raana Zakeri is a Ph.D, candidate in Epidemiology at the University of North Carolina at Chapel Hill,, with nearly a decade of experience in injury research and prevention from both international settings and her work at the UNC Injury Prevention Research Center. Her research focuses on developing real-world prevention solutions for injuries, with multiple publications in this area. Raana joined DAN in 2014, where she has dedicated her work to the prevention of diving injuries and the advancement of diving safety within the research department under the supervision of Dr. Tillmans, including collaborative projects between DAN and UNC.

She analyzes long-term trends in diving injuries spanning nearly 25 years, examining injury types, fatality incidence, and locations of incidents. This work provides rare and valuable insight in a field where globally available data remain limited. Raana also examines diving injury rates and associated risk factors through large-scale survey studies among DAN members. In addition, she contributes to improving post-treatment guidance for divers treated for decompression illness, with the goal of preventing symptom recurrence or worsening. Raana has explored real-world clinical management of diving injuries by examining patterns of barotrauma diagnosis across healthcare settings. A central aspect of her work is its interdisciplinary and interdepartmental focus on strengthening injury surveillance. One of her key projects involves developing a comprehensive diving injury registry that integrates multiple internal and external data sources to support strategic oversight, informed decision-making, and effective prevention planning to advance diver health and safety.

Dr. Vincent Benoit

Data Architect and Software Developer

Vincent Benoit is a passionate recreational diver that started collaborating with DAN Research in 2025. Born in Brest, France, he has been fascinated by Jacques Cousteau and sea exploration since a young age. Although he only started diving in 2019, he has not stopped since. From Imagine Institute to Greater Paris University Hospital, Vincent has nearly 20 years of experience in IT, with a focus on managing medical research data. His main areas of expertise include interoperability, standardization, and, above all, providing researchers with the means to store and analyze their data in a secure way. At DAN, he serves as a bridge between researchers and IT, helping to build tools to gather data and enhance knowledge around diving and hyperbaric medicine.

Dr. Lesley Blogg

Research Consultant, Medical Writer, and Editor

Lesley Bogg has been part of the DAN Research team since 2023, and also runs SLB Consulting from her home in the north-west of England. She started her scientific career with at Birmingham University, UK, with a scholarship studying the diving response in birds and mammals. In 1999 after achieving her doctorate, she took a sideways step to human divers, studying decompression illness and submarine escape and rescue strategies at QinetiQ, UK. She also trained as a hyperbaric paramedic attendant and engineer. In 2002 she became a research post doc at the Karolinska Institute working with the Swedish Navy, an alliance that continued on her return to the UK until 2019.

In 2014, she was appointed the European (Deputy) Editor of the Diving and Hyperbaric Medicine (DHM) Journal, a role she continues to date. In 2019, she widened her skill set, working as a medical writer for an international medical communications agency, where she honed her writing and editing skills. In 2021 she started a research collaboration with the University of California at San Diego, DAN, Duke University and the University of Chapel Hill, working on a project collating the Big Doppler Database. Having helped DAN with their Annual Diving Report (ADR) in the past, Lesley became part of the research team in late 2023 and took on responsibility of producing the ADR. She also ran the 2025 DAN Research Workshop – the second consensus meeting on Ultrasound in Diving research – in Summer 2025, having arranged the inaugural meeting in Sweden back in 2015.

Rhiannon Brenner

Graduate Research Scholar

Rhiannon Brenner graduated from the University of North Carolina at Chapel Hill in 2021 with a bachelor’s degree in Biological Anthropology, and in 2025, attained a master’s degree in Physiology from the University of Western Brittany in Brest, France. She has been diving since she was 16 years old, and continued working her way through training, becoming a Divemaster in 2020 and a technical diver in 2022. Rhiannon has a specialized interest in the variation that exists within underwater physiology and has been working on studies such as DAN’s New Bubble study in an attempt to narrow down possible physiological contributors to increased decompression stress. She is currently pursuing a Ph.D. at the University of Western Brittany, where she studies the variation in decompression stress amongst women divers.

Sherri Ferguson

Injury Monitoring Liaison, Canada

Sherri Ferguson is a Canadian scientist and expert in hyperbaric and diving physiology. She is the president of Shanfe Research & Consulting Ltd., and a DAN Research Associate. She was the Director of the Environmental Medicine and Physiology Unit (EMPU) at Simon Fraser University for 18 years, where she oversaw all research into the physiological effects of hyper and hypobaric environments. A professional diver, Ferguson is dedicated to advancing safety standards in the diving community and is the Vice Chair of the Canadian Standards Association Z275 Occupational Diving and Hyperbaric standards and is the Chair of the sub-committee on Hyperbaric operations and work in compressed air environments. She serves on many diving and hyperbaric committees including UHMS Hyperbaric Safety, the Canadian Association for Underwater Science executive committee, and Scuba Diving International training advisory council and a Director at Large on the Board of the Canadian Undersea and Hyperbaric Medical Association. She is also the first Canadian recipient of the Paul C. Baker Award for excellence in hyperbaric oxygen therapy safety, underscoring her significant contributions to science and public health.

Doug Fraedrich

Decompression Modeling and Biostatistician

Doug Fraedrich earned a bachelor’s degree in Physics from the College of William and Mary and a master’s degree in Applied Statistics from the George Washington University. During his 30-year career as a scientist for the US Navy, he developed methodologies to rigorously validate scientific models using limited and imperfect data. An avid diver for 25 years, he enjoys wreck diving around the world. Since retiring as a Navy scientist, he has enjoyed combining his expertise on the validation of scientific models with his diving hobby, researching how to best test and validate decompression models. He has been a consultant for DAN since February 2024.

Dr. Jana Johnson

Injury Monitoring Consultant

Dr. Johnson is a retired pulmonary and critical care physician. She also obtained a Master of Public Health in Preventive Medicine and worked for the North Carolina State Health Department as director of tobacco cessation. She has a Divemaster certification and enjoys underwater photography. She volunteers with Diving With a Purpose (DWP) as an instructor, helping to teach other divers the basics of underwater archeology. Jana is very happy to be volunteering with DAN Research helping to prepare reports from the DAN Incident Reporting System for use by DAN to promote dive education and safety.