Dr. Hawa Abdi and her daughters, Dr. Deqo Mohamed and Dr. Amina Mohamed, treat Somali refugee women and children, often for free.

Samuel Cohen researches Alzheimer's disease and other neurodegenerative disorders.

Photojournalist James Nachtwey is considered by many to be the greatest war photographer of recent decades. He has covered conflicts and major social issues in more than 30 countries.

Professor Sajay Samuel's proposal to reduce the burden of student loans is part of his larger preoccupation with thinking beyond the conventional categories of economics and ecology.

Halima Aden was the first ever hijab-wearing fashion model.

Billy Samuel Mwape is a computer scientist, project management expert and business strategist with more than 16 years of experience in the banking and mining sectors.

Paul Conneally is the public communications manager for the International Federation of the Red Cross and Red Crescent Societies, and a leader in using digital technologies for humanitarian aid.

Human rights advocate Mohamed Ali fights terrorism with entrepreneurship.

Zoologist Dr. Lucy King helms the Human-Elephant Coexistence Program for the Kenyan research charity Save the Elephants.

One of Australia's foremost tech leaders, Jamila Gordon is CEO and founder of Lumachain.

Janine di Giovanni reports from war zones around the world.

Samantha Nutt envisions a world where no child knows war.

Luma Mufleh does something revolutionary: she coaches soccer. A Jordanian immigrant and Muslim of Syrian descent, Mufleh is determined to empower refugee children everywhere.

Could our culture have misdiagnosed violence? As the director of the initiative Cure Violence, Gary Slutkin approaches gunfire on neighborhood streets as a contagious disease, looking to science and public health for strategies to stop it.

Photojournalist