Talk of the Nation

One week ago, two bombs rocked the finish of the Boston Marathon, killing three people and injuring more than 170 others. Some of the injured lost limbs in the explosion and now face a long and difficult recovery period.

Investigators in the Boston Marathon bombings were able to identify the suspects using footage from surveillance cameras. Some believe that this shows the need for surveillance cameras in public spaces, while others believe that such cameras encroach on our civil liberties.

South Sudan is the world's newest country, and with stunning wildlife and plentiful oil reserves, it's got the raw materials to thrive as a tourist attraction. The African nation's new independence also shed light on what it lacks: infrastructure, government and stable civil society.

Now in its 43rd year, Earth Day has become an international day dedicated to promoting environmental awareness and action. Lester Brown, president of the Earth Policy Institute, explains what's changed, as concern about climate change and green energy have come to the forefront of the movement.

After a swift investigation, law enforcement identified the suspects as brothers Tamerlan and Dzhokhar Tsarnaev. As investigators piece together a timeline and motive, many questions are still unanswered. NPR's Dina Temple-Raston explains where the investigation goes from here.

News of the bombings at the Boston Marathon on April 15, 2013 made headlines around the world. Boston Globe columnist Dan Shaughnessy talks about the significance of the events for himself and fellow Bostonians one week after the attack.

In his latest book Hallucinations, neurologist Oliver Sacks collects stories of individuals who can see, hear and smell things that aren't really there--such as strange voices, or collages of unrecognizable faces--and explores the disorders and drugs that can produce such illusions.

Writer Barbara Kingsolver is one of a handful of novelists with a science background, and she puts it to use in her new novel Flight Behavior. Kingsolver discusses the book and why she chose to look at the the issue of climate change in a fictional work set in rural Tennessee.

Deep-sea voyager Robert Ballard has discovered everything from 10-foot-tall tube worms to the Titanic on his ocean expeditions around the world. Ballard discusses his underwater finds and how new robotic technology allows scientists to explore the sea from ashore.

What happens when scientific research borders on science fiction? Michael Belfiore, author of the new book The Department of Mad Scientists, talks about the bizarre projects happening behind the scenes at DARPA — the secretive research arm of the Department of Defense.

Explosions at the Boston Marathon, potentially ricin-laced letters intercepted en route to the White House and Sen. Roger Wicker, and an explosion at a fertilizer plant in Texas have each prompted investigations. In each case, authorities sift through evidence to construct a timeline of events.

Fifteen-year-old Malala Yousafzai has become a symbol of hope for change in Pakistan and the world. Since her near-fatal shooting in 2012, her voice and reach has grown, as she speaks out against the Taliban's influence, and advocates for education for Pakistani youth.

After the bombings in Boston, law professor Khaled Beydoun was gripped by the fear that the culprit would be found to be an Arab or Muslim American. Since Sept. 11, 2001, he says this anxiety has become quite familiar in Arab and Muslim communities, and that has transformed the grieving process.

Race and ethnicity influence nearly all aspects of American life. Matt Thompson, leader of NPR's race, ethnicity and culture team Code Switch, and Beverly Cross, professor of urban education at the University of Memphis, discuss how the relationship between ethnicity and identity morphs over time.

Many of those injured, and at least two of those who were killed, in the Boston Marathon explosions were there to cheer the runners on. Runners count the smiles, cheers and witty signs from spectators to motivate them along the way. Runner and writer Erin Ryan talks about what spectators contribute.