Some experiments on very resinous Longleaf Pine specimens indicate an increase in strength, due to the resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby.
What is fat lighter practically impervious to in addition to termites?
rot

Worldwide use of solar power and wind power continued to grow significantly in 2012. Solar electricity consumption increased by 58 percent, to 93 terawatt-hours (TWh). Use of wind power in 2012 increased by 18.1 percent, to 521.3 TWh. Global solar and wind energy installed capacities continued to expand even though new investments in these technologies declined during 2012. Worldwide investment in solar power in 2012 was $140.4 billion, an 11 percent decline from 2011, and wind power investment was down 10.1 percent, to $80.3 billion. But due to lower production costs for both technologies, total installed capacities grew sharply. This investment decline, but growth in installed capacity, may again occur in 2013. Analysts expect the market to triple by 2030. In 2015, investment in renewables exceeded fossils.
In what year did investment in renewables exceed fossils?
2015

During the rule of the Fatimid and Mamluk dynasties and their successor states in the medieval Middle East, many of the ruling elite founded madaris through a religious endowment known as the waqf. Not only was the madrasa a potent symbol of status but it was an effective means of transmitting wealth and status to their descendants. Especially during the Mamlūk period, when only former slaves could assume power, the sons of the ruling Mamlūk elite were unable to inherit. Guaranteed positions within the new madaris thus allowed them to maintain status. Madaris built in this period include the Mosque-Madrasah of Sultan Ḥasan in Cairo.
What class of people inherited status during the Mamluk Period?
former slaves