Starch residue analysis was carried out on stone tools recovered from the bottom layer of the Anakena site on Rapa Nui (Easter Island). These deposits have been dated to AD 1000-1300 AD and so far, represent the earliest evidence of human settlement on this island. Twenty obsidian tools were analyzed.
View Article and Find Full Text PDFIn Open Dialogue, sharing of reflections by professionals constitutes an important contribution to promoting a polyphonic dialogue between participants. In the inner dialogue, past and future influence the present moment. In this study, we explore the influence of sharing or withholding reflections by professionals on the interplay between inner and outer dialogue.
View Article and Find Full Text PDFMetal chalcogenides are important materials for a myriad of devices, but the ability to control their porosity is lacking. We report a method of inducing hierarchically ordered porosity using surface-treated nanocrystals and complementary architecture-directing agents. The resulting mesoporous materials are robust to thermal annealing and chemical transformations.
View Article and Find Full Text PDFWe report on the first observation of optically excited surface plasmon polaritons (SPPs) in the conducting phase of vanadium dioxide (VO(2)) thin films. VO(2) is low-loss optical material that undergoes an insulator-metal transition (IMT) under suitable thermal, optical, or electrical stimulation, thus enabling tunable SPP excitation of the conducting phase. Here we applied IR light (1520 nm) to excite SPPs while thermally inducing the IMT by changing the VO(2) temperature, and observed a clear trend from nonabsorption in the insulator phase to high absorption in the conducting phase due to SPP excitation in the latter phase.
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