About this issue Abstract Time domain reflectrometry (TDR) has been used by soil scientists for many years to measure the volumetric water content of soils. The basic theory relating the dielectric ...

Wanna see a trick? Give us any topic and we can tie it back to the economy. At Planet Money, we explore the forces that shape our lives and bring you along for the ride. Don't just understand the ...

The currency value of the SDR is determined by summing the values in U.S. dollars, based on market exchange rates, of a basket of major currencies (the U.S. dollar, Euro, Japanese yen, pound sterling ...

It takes a lot of brainpower to run a country—see how the top presidents stack up! Here are the smartest presidents, ranked by IQ.