What does this equation mean?

The device geometry is a bending-beam flexure cell: clamp a thin slab of the crystal at its ends, bend it to a controlled radius of curvature, and the resulting surface strain varies smoothly along the beam, sweeping the local tilt through the critical value across a channel roughly a hundred nanometres to a micrometre long. The line where the tilt crosses 1 is the horizon, with an analog surface gravity set by how fast the tilt changes along the channel and an analog Hawking temperature that follows from it in the same way a real event horizon’s surface gravity fixes its radiation temperature. At the paper’s chosen design point — a Fermi velocity of 2$\times$10^5 metres per second, a strain of three-tenths of one percent delivered over a hundred-nanometre channel — the analog Hawking temperature comes out around a tenth of a kelvin, comfortably inside dilution-refrigerator range, with the design envelope spanning roughly 0.04 to 0.4 kelvin depending on how the channel length and strain sensitivity are chosen. None of the mechanical pieces of that design are new on their own: the strain itself can be delivered by a piezoelectric bending-beam cell of the kind Clifford Hicks and Andrew Mackenzie’s group built for tuning correlated-electron materials, reaching continuously tunable, reversible strain up to about 0.23 percent at cryogenic temperature [ 7 ] , and ohmic contacts to a transition-metal ditelluride channel are available by laser phase-patterning a metallic region directly into the semiconducting crystal, a technique that raised a MoTe _2 transistor’s mobility roughly fifty-fold while holding a million-to-one on/off ratio [ 8 ] .