January-February 2019

Current Issue

January-February 2019

Volume: 107 Number: 1

For about 2,000 years, starting in about 1000 BCE, the Maya city of El Ceibal was a bustling urban center with an estimated peak population of up to 52,000 inhabitants. Today this important archaeological site is almost inaccessible beneath farmlands, modern settlements, and protected forest, but archaeologists can create a detailed map of the site, thanks to a laser-based technique known as airborne lidar, short for light detection and ranging. As explained in “Estimating Ancient Populations by Aerial Survey,” the technique calls for aircraft with specialized laser equipment to fly slowly over the site, collecting topographic information from laser reflections from the ground, archaeological structures, and vegetation. Computer programs then create a contour map of the area that includes buildings, earthworks, irrigation canals, and roads, with decimeter accuracy. (Lidar data collected and image created by the National Center for Airborne Laser Mapping.)

In This Issue

  • Art
  • Biology
  • Chemistry
  • Communications
  • Computer
  • Engineering
  • Environment
  • Ethics
  • Evolution
  • Medicine
  • Physics
  • Policy
  • Technology

Is Wildlife Conservation Policy Based in Science?

Kyle A. Artelle

Environment Policy

Common claims that management of animal populations in the United States and Canada is “the best in the world” and “science-based” are often unfounded. But substantial improvements are possible.

Random Paths to Frequency Hopping

Tony Rothman

Communications Technology

Actress Hedy Lamarr famously co-patented a widely used secure communication technology, but popular accounts overlook many predecessors.