Our Team

Marni Sommer, Professor of Sociomedical Sciences, Director of GATE 

Marni Sommer, DrPH, MSN, RN, has worked in global health and development on issues ranging from improving access to essential medicines to humanitarian relief in conflict settings. Dr. Sommer's particular areas of expertise include conducting participatory research with adolescents, understanding and promoting healthy transitions to adulthood, the intersection of public health and education, gender and sexual health, and the implementation and evaluation of adolescent-focused interventions. Dr. Sommer presently leads the Gender, Adolescent Transitions and Environment (GATE) Program, based in the Department of Sociomedical Sciences. GATE explores the intersections of gender, health, education and the environment for girls and boys transitioning into adulthood in low-income countries and in the United States. GATE also generates research and practical resources focused on improving the integration of menstrual hygiene management and gender-supportive sanitation solutions into global humanitarian response.


Sarah Blake, Senior Research Program Manager

Sarah Blake, PhD, MPH, MSc has worked at the intersections of research and programming in gender, adolescent health and well-being and rights across diverse global contexts, including West Africa and Central Asia. Her research focuses on qualitative and participatory research on the health and social dimensions of adolescents’ transitions to adulthood. Dr. Blake has contributed to policy and evidence reviews, and program evaluations of health and educational interventions in school and community settings. In addition, she has worked with community, national, and international non-governmental organizations to gather and translate evidence into adolescent-centered, community-based programming. Dr. Blake holds a PhD in Sociology from the University of California, San Francisco, an MPH in Population and Family Health from Columbia University, and an MSc in Gender, Development, and Globalisation from the London School of Economics and Political Science. 


Angela Nguyen, Postdoctoral Research Scientist

Angela Nguyen, DrPH, MPH, is a postdoctoral research scientist for the GATE Program. She earned her doctorate from the University of California, Berkeley School of Public Health and her MPH from the New York University School of Global Public Health. Angela’s interdisciplinary research to date has focused on vulnerable populations, social determinants of health, and environmental exposures. Her dissertation centered on the epidemiology of disaster mental health, particularly the community- and individual-level factors associated with mental health recovery among displaced women survivors. More recently, she collaborated on a quantitative research study on the impacts of the COVID-19 pandemic on period poverty in the U.S. With GATE, Angela will engage on several research projects ranging from examining the dissemination of puberty educational content to young people, to assessing the impact of menstrual health on the daily lives of those with periods.


Sadie Bergen, Research Assistant

Sadie Bergen, MA, is a fifth year PhD student in the Department of Sociomedical Sciences where she is a predoctoral fellow in Gender, Sexuality and Health. Her research examines the ways that institutions like hospitals and corporations have historically shaped reproductive health access and outcomes. Her dissertation project traces the history of neonatal intensive care in the United States. In her time at Columbia, Sadie has participated in qualitative research on a range of subjects related to reproductive health equity, including the experiences of women living with HIV and the role of pro-choice physicians play in abortion politics. 

Sarah Branoff, Research Assistant

Sarah Branoff is pursuing her Master of Public Health at Columbia Mailman School of Public Health in the Department of Population and Family Health. She has a background in child-focused community development and global health programs, having worked with national and international organizations to improve the health of kids and communities. Most recently, Sarah worked with FHI 360 to manage programs responding to HIV and COVID-19 in Latin America, Southeast Asia and Central Africa. Sarah is interested in public health program design and adolescent sexual and reproductive health, with a particular interest in menstrual health. Sarah is from California and has a BA in Public Health from UC Berkeley.

Sally Kim, Communications and Social Media Assistant

Sally Kim is a second-year MPH student in the Department of Health Policy and Management with a certificate in Health Communication. Sally supports the GATE program as the Communications and Social Media Assistant. She graduated from the University of California Berkeley with a BA in Public Health in 2020. Prior to Mailman, she worked in Portland, Oregon as a CDC Public Health Associate supporting ScreenWise, Oregon’s breast and cervical cancer program. Sally's areas of interest in public health include

promoting equitable access to health care and improving health literacy.


Gabriella Modesti, Global Mental Health Intern

Gabriella Modesti is a senior at Skidmore College with a major in Psychology with a minor in Gender Studies. She was a summer intern for Columbia’s Global Mental Health Programs when she began working alongside the GATE team. Gabriella has participated in research at Skidmore focusing on the intersections of gender, race, and stigmatization in the field of mental health, as well as studies revolving around how children think and learn about the social world. During the summer of 2023, she worked on a project with GATE assessing the relationship between menstrual health management and mental health.