Talk of the Nation

The bombings at the Boston Marathon have lead to heightened security across the world. Organizers of the London Marathon contacted local police to discuss increased security measures. Officials in California monitored its emergency system after the blast.

Hours after the bombing at the Boston Marathon on Monday, the president reminded the country of its resilient nature and assured the public that those responsible will be brought to justice. Wednesday, the toxic substance ricin was detected in mail addressed to the White House.

In the hours after the Boston Marathon bombings, social media was alight with offers of assistance — from restaurants inviting guests to pay what they could, to Bostonians offering couches and inflatable mattresses to anyone who needed a place to stay.

Less than 24 hours after two explosions rocked the finish line at the Boston Marathon and there are still more questions than answers about what happened. Three people were killed and more than 170 were injured. The FBI is investigating the event as an act of terrorism.

The Senate's Gang of Eight will roll out comprehensive immigration reform legislation Wednesday. The law is expected to create a path to citizenship for the estimated 11 million individuals living in the U.S. illegally, beef up border security and enhance the country's legal immigration system.

In the moments following the twin explosions at the Boston Marathon, many of the initial reports disseminated through social media proved to be false. Jeremy Stahl, social media editor for Slate.com, shares his rules for social media responsibly in the midst of tragic, breaking news.

Two apparent explosions have rocked the finish line at the Boston Marathon, about three hours after the winners crossed the finish line. The explosions occurred as thousands of runners finished running 26.2 mile course at the 117th Boston Marathon. NPR's Tovia Smith provides an update.

Chilean poet Pablo Neruda was exhumed in early April, with the goal of discovering whether the poet's death was from prostate cancer or poison. In a The New York Times op-ed, Amherst College professor Ilan Stavans argues that Neruda's legacy is more important than the way he died.

According to the National Registry of Exonerations, more than a thousand individual have been exonerated in the U.S. since 1989. After a wrongful conviction, the lives of both the accused and the victim are permanently altered.

A system known as "return-free filing" would allow filers to receive a pre-filled tax return prepared by the government and make any necessary tweaks. According to a ProPublica-NPR report, this approach, which exists in some countries, has taxpayer advocates at odds with tax preparation companies.

Reporting in Nature Medicine, researchers write that a chemical in red meat, L-carnitine, may up the risk of heart disease in people and mice--but only in frequent red-meat eaters. Study author Stanley Hazen of the Cleveland Clinic explains how diet changes the gut's bacterial flora, and how that can affect heart health.

Bacteriophages, viruses that infect bacterial cells, employ an arsenal of chemical weapons. Microbiologist Vincent Fischetti of Rockefeller University describes using tricks learned from the phage in developing new antibiotics that may be effective even where others fail.

Last month monarch butterflies began an annual northward journey from their overwintering habitat in Mexico. Monarch expert Lincoln Brower discusses the dwindling monarch populations, and explains how habitat loss in Mexico and a decline in milkweed plant numbers in the U.S. may be harming the familiar orange and black fliers.

Brewing coffee is a neverending science project, according to barista Sam Penix, owner of Everyman Espresso in New York City. Grind-size, brew method, coffee beans (which are really seeds), water temperature can all affect the flavors that end up in your cup. Harold McGee, author of On Food and Cooking, explains some of the chemistry of coffee.

In Gulp. Adventures on the Alimentary Canal, science writer Mary Roach takes a journey through the gut, from the secret healing powers of saliva to the taxonomy of poop. Along the trip, she serves up odd medical anecdotes, such as the story of William Beaumont, an eccentric surgeon who once ate chicken from another man's stomach.