ABSTRACT
In research on early invention and innovation, technological "firsts" receive enormous attention, but technological "lasts"-instances of abandonment and rejection-are arguably more informative about human technological behavior. Yet, cases of technological discontinuance are largely ignored in studies of early innovation, as the lack of robust datasets makes identification and analysis difficult. A large-scale geospatial analysis of more than 4500 gold objects from the Caucasus, an early center of gold innovation, shows a precipitous decline at 1500 BC in precisely the places with the earliest global evidence of gold mining (c. 3000 BC). Testing various causal models reveals that social factors, rather than resource limitations or demographic disruption, were the primary causes of this rejection. These results indicate that prior models of technological rejection and loss have underestimated the range of conditions in which they can occur, and provide empirical support for theories of innovation that reject notions about the linearity of technological progress.
ABSTRACT
Optical polarization, absorption, and scattering studies along with confocal microscopy reveal that Benzopurpurin 4B forms aggregates of micrometer size at very low concentrations in aqueous solution. A chromonic liquid crystal phase is stable at room temperature down to concentrations as low as 0.4 wt %, which can only be possible if the aggregates contain an ample amount of water. The kinetics of aggregate formation are extremely slow, with changes going on for days before equilibrium is reached. The stacking free energy change is estimated to be 10.3 +/- 0.4 k(B)T, which is in the higher range of values for recently studied chromonic liquid crystals. However, the very low concentration of the liquid crystal phase puts it in a different class, probably more similar to Scheibe or Jelly aggregates than the typical chromonic systems that are formed by simple stacks of molecules.
