Hunting and gathering was presumably the subsistence strategy employed by human societies beginning some 1.8 million years ago, by Homo erectus, and from its appearance some 0.2 million years ago by Homo sapiens. It remained the only mode of subsistence until the end of the Mesolithic period some 10,000 years ago, and after this was replaced only gradually with the spread of the Neolithic Revolution.
What phase of human used subsistence strategies to find food?
Homo erectus

A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.
Why is the use of solar balloons typically limited to the toy market?
the surface-area to payload-weight ratio is relatively high

The Midwest Regional Medical Center located in the suburb of Midwest City; other major hospitals in the city include the Oklahoma Heart Hospital and the Mercy Health Center. There are 347 physicians for every 100,000 people in the city.
Where is the Midwest Regional Medical Center?
Midwest City