This period also saw some contacts with Jesuits and Capuchins from Europe, and in 1774 a Scottish nobleman, George Bogle, came to Shigatse to investigate prospects of trade for the British East India Company. However, in the 19th century the situation of foreigners in Tibet grew more tenuous. The British Empire was encroaching from northern India into the Himalayas, the Emirate of Afghanistan and the Russian Empire were expanding into Central Asia and each power became suspicious of the others' intentions in Tibet.
Who came to Tibet from Europe?
Jesuits and Capuchins

High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens. LED power densities up to 300 W/cm2 have been achieved. Since overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from a HP-LED is not removed, the device will fail in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.
Why must High-power LEDs be mounted on a heat sink?
to allow for heat dissipation

The five Great Lakes are located in the north-central portion of the country, four of them forming part of the border with Canada, only Lake Michigan situated entirely within United States. The southeast United States contain subtropical forests and, near the gulf coast, mangrove wetlands, especially in Florida. West of the Appalachians lies the Mississippi River basin and two large eastern tributaries, the Ohio River and the Tennessee River. The Ohio and Tennessee Valleys and the Midwest consist largely of rolling hills and productive farmland, stretching south to the Gulf Coast.
What type of land makes up the Ohio and Tennessee valleys?
rolling hills and productive farmland