Our Team

Our Team

One Tree Learning Institute's team brings decades of front-line experience in fire fighting, emergency services, veteran's health, and cutting-edge professional education and academic research to help our partners develop strength and resiliency.


Dr. Michael Marks

Executive Director
Michael Wm. Marks, Ph.D., ABPP: Dr. Marks is currently the Executive Director of the One Tree Learning Institute. He is a former Professor of Practice in Psychology and Program Director of the Supportive Education for Returning Veterans at the University of Arizona. Previously, he served as Lead Psychologist and Evidence Based Practices Coordinator at the Southern Arizona VA Health Care System. Dr. Marks has functioned as the PTSD Outpatient Clinic Team Leader and as a PTSD Mentor for VA Hospitals across Arizona, New Mexico and West Texas. Dr. Marks was co-founder of Vietnam Veterans of Montana and has received the Disabled Americans Veterans Humanitarian Award. He was selected as the 2012 “Outstanding Clinician of the Year” by the American Psychological Associations Division 18, VA Section. He is also co-developer of the nationally recognized, Supportive Education for Returning veterans (SERV) program, which is a cohort based curriculum designed to help veterans transition from military to academic life. The SERV curriculum has been cited by the Veteran’s Administration (VAOIG) as a best practice and is part of the VA’s “Strong Practices Project.” He received the 2019 "Sarah Haley Memorial Award for Clinical Excellence" presented by the International Society for Traumatic Stress Studies. Dr. Marks has co-authored numerous books and articles and presented nationally on resilience and post-traumatic growth. He and his colleagues at One Tree Learning Institute provide resilience training to members across the healthcare and public service communities. Dr. Marks has dedicated his career to working with trauma survivors, both military and civilian, adults and children, for the last 44 years.

Jeff Dyar

Vice President for Resiliency Training
Jeff Dyar is in his 4th decade of public service as an emergency responder. He has operated as a Paramedic, firefighter, emergency manager and an educator/author during that time. Jeff has responded to some of the largest and most high profile incidents in American history such as both World Trade attacks, Oklahoma City Bombing, Flight 232 Sioux City Iowa Plane Crash, Columbine High School Shootings to mention a few. He has also has responded to several large national security events, natural disasters such as hurricanes, tornadoes, floods, wildfires, riots and large hazardous materials incidents. Jeff held a Program Chair position at the National Fire Academy in Emmitsburg, MD for a decade and has worked as an instructor at four community colleges and two major Universities. Jeff received the James O. Page Award for contributions to advancing EMS on a national level, given by the EMS Section of the International Association of Fire Chiefs. As an author he has authored or co-authored four major book titles, written dozens of news and magazine articles and served on several Media Boards. Jeff currently resides in South West Colorado and is the Board President of a Local Fire District that provides ALS level EMS transport services and Structure/Wildland Fire mitigation and suppression to a 285 Sq mile area.
Amy Devins

Amy Devins

Ms. Amy Devins leads the First Responder Services and Urgent Engagement teams within the Crisis Services and Justices Services Division of Arizona Complete Health-Complete Care Plan, the Regional Behavioral Health Authority (RBHA) in eight Southern Arizona counties. In this role, Ms. Devins and her staff are responsible for developing partnerships with first responder agencies to increase first responder confidence in, and usage of, crisis system alternatives to detention and emergency departments. With 15 years of experience as a detective and patrol officer in Colorado and Wyoming, Ms. Devins understands the need for robust crisis services ready to serve their communities. She is a proud University of Iowa alumna and a passionate advocate of emergency services peer support programs, Critical Incident Stress Management (CISM), Resiliency: 5 Skills training, Mental Health First Aid (MHFA) and Crisis Intervention Teams (CIT). Additionally, Ms. Devins serves as Vice-Chair of the Hearts of Gold Police Family Outreach Foundation.
Tony Lo Giudice1

Dr. Tony Lo Giudice

Tony is the Public Health Director for Alamance County, North Carolina and served previously as a fire captain-paramedic for the City of Mesa, AZ. He has 20 years of experience in public administration and public policy with an emphasis on public safety. He has worked in city management and as a policy consultant to local, state, and federal officials. He also served as project director for the Centers for Medicare and Medicaid funded Community Care Initiative project, which was a $12.5 million-dollar collaboration between local government, fire departments, EMS services, behavioral health, hospital systems, non-profits, universities, and private businesses. Tony has had the honor and privilege to serve as a co-investigator for first responder behavioral research, for which he has trained over 700 firefighters/EMS, police officers, nurses, 911 dispatchers and social workers from Arkansas, Arizona, California and Colorado in stress-related illness prevention and post-traumatic growth.
Wanda Larson

Dr. Wanda Larson

Ph.D., M.Ed, Rn, CEN, CPEN
Dr. Larson is a professor teaching, part time, at the UA College of Nursing and in other healthcare Inter-professional coursework. She regularly instructs ACLS, PALS, BLS, paramedic refreshers, Emergency Nurse Pediatric and Advanced Trauma Nurse workshops. She serves on the planning committee for statewide trauma conferences and for EMS on the border conferences. Dr. Larson has been involved in developing resiliency training within emergency response work for more than 47 years. Her career began in Search and Rescue which led to her becoming an EMT, a Paramedic Educator, a Flight Nurse, a Certified Emergency Nurse and a Certified Pediatric Emergency Nurse. She has been involved in Critical Incident Stress Management (CISM) education and responded in emergency response and disaster work, as well as been involved in teams providing peer support. Dr. Larson has worked with Dr. Michael Marks and Dr. Phil Callahan, along with her nursing colleagues to transition the Resiliency 5 Skills training into the College of Nursing's Master's Entry to Nursing Degree program, the Doctor of Nursing Practice degree program and “train-the-trainer” resilience workshops for emergency providers, educators and other high stress professions.

Dr. Phil Callahan

Technical Advisor & Author
Dr. Callahan has served as Assistant Director of the Division of Academic Resources, Arizona Health Sciences Center (AHSC), University of Arizona, Associate Professor and Program Coordinator, Educational Psychology, University of Arizona South, Associate Professor of Veterans Education, College of Agriculture and Life Sciences, University of Arizona and is currently Emeritus, Professor University of Arizona. He has developed Server-based test diagnostic application software to help educators identify and intervene with at risk students (CatTrax) and has spent his professional career assisting faculty in improving the retention and graduation of their students. Dr. Callahan has written and presented nationally on issues related to academic success among student veterans. Along with his academic career he also served southern Arizona as a paramedic and firefighter. In 2013, Dr. Callahan was named “Top 10 Innovators in Emergency Medical Services.” He currently serves as Director of Research and Development for One Tree Learning Institute and Resilient Hacks.
Nathan Hogan

Dr. Nathan Hogan

Nathan is a retired veteran, having served nearly 22 years in both the U.S. Air Force and Army. His military experience included multiple combat tours in Iraq and Afghanistan as well as numerous operational deployments around the world. Nathan earned his M.A. in History with a concentration in Global History from American Military University and his Ph.D. in Mythological Studies with emphasis in Depth Psychology from Pacifica Graduate Institute. He served on the senior committee for the University of Arizona’s College of Humanities “Thunder of War – Winds of Return” project, focused on using important humanities sources to create dialogues about the experience of war. Nathan currently serves on the board of KMK Yoga, a 501.3C non-profit that brings the healing aspects of yoga to underserved communities. His academic focus is studying ancient mythologies from around the world that are concerned with martial lifeways and bring that wisdom into modern practice for servicemembers, veterans, and first responders. He emphasizes bringing the cornerstone values of service into harmony with one’s life to “live forward.” Nathan currently works as a senior analyst for Titania Solutions Group, Inc.