PBS NewsHour

Tonight on the program, we take a look at the devastating tornado that hit Moore, Oklahoma earlier today that has left massive destruction and dozens dead. Also: Assad tries to retake border town in Syria, Yahoo makes a deal to acquire Tumblr, a new beginning to U.S.-Myanmar relations, coding skills combine with civics to improve government, and what an updated DSM-5 means for diagnosing patients.

The American Psychiatric Association released a new edition of the DSM, which doctors use to diagnose and treat mental disorders. Judy Woodruff discusses the changes and implications for both patients and professionals with Dr. Michael First of Columbia University and Dr. Steven Hyman of the Broad Institute.

Code for America, a San Francisco nonprofit, enlists high tech professionals to work with local governments to create tools to help average citizens tackle hunger, blight and other civic problems. NewsHour correspondent Spencer Michels reports.

At the White House, President Barack Obama welcomed Myanmar President Thein Sein, the first Burmese leader to visit Washington in nearly five decades. Ray Suarez talks to Jennifer Quigley of the U.S. Campaign for Burma and Priscilla Clap, former chief of the U.S. mission in Myanmar, about reforms in that country.

In Syria, Assad government troops pushed to retake the strategic town of , close to the border with Lebanon. Hezbollah fighters joined the Syrian regime army in laying siege to Qusayr, home to 40,000 civilians. Judy Woodruff reports on the growing involvement of Hezbollah in the Syrian conflict.

In other news Monday, a wave of sectarian killings across Iraq left at least 95 people dead. It was the single-worst day of violence in Iraq in more than a year and a half. Also The New York Times reports that computer hackers in the Chinese military have resumed attacks on U.S. companies and government agencies.

Two tornadoes struck the Oklahoma City area within 24 hours, leaving behind miles of devastation and leveling scores of homes. Kwame Holman reports on the extreme weather in Oklahoma. Jeffrey Brown talks to Gary Knight of the Oklahoma City Police Department and Bill Bunting of the National Severe Storm Prediction Center.

Tech company Yahoo bought Tumblr for a reported $1.1 billion, adding the fast-growing social media site with more than 100 million blogs to its roster of assets. Jeffrey Brown talks with Rebecca Lieb, a research analyst for the Altimeter Group, about the appeal of the image-centric and mobile-friendly blogging platform.

Science Correspondent Miles O'Brien talks with Jeffrey Brown about the legacy of astronaut Sally Ride.