The development of single-step printable holographic recording techniques can enable applications in rapid data storage, imaging, and bio-sensing. The personalized use of holography is limited due to specialist level of knowledge, time consuming recording techniques, and high-cost equipment. Here, we report a rapid and feasible in-line reflection recording strategy for printing surface holograms consisting of ink using a single pulse of a laser light within seconds. The laser interference pattern and periodicity of surface grating as a function of tilt angle are predicted by computationally and demonstrated experimentally to create 2D linear gratings and three-dimensional (3D) images. We further demonstrate the utility of our approach in creating personalized handwritten signatures and 3D images.
The chipped stone industry of Cihuatan and Santa Maria, Postclassic sites of north-central El Salvador, is discussed briefly in terms of behavioral/technological typology. The industry was based almost exclusively on obsidian and emphasized specialized production of prismatic blades. Source determinations by X-ray fluorescence and neutron activation analysis of 20 obsidian specimens from Cihuatan indicate that at least three highland Guatemalan sources supplied obsidian to the site. Twelve specimens are attributed to the Ixtepeque source, seven to El Chayal, and one to San Martín Jilotepeque. The multiple-source procurement pattern is interpreted as a hedge against the fragility of Postclassic sociopolitical alliances and shifting exchange networks.
Salvage excavations in 1977–1978 of Structure E3-7 at Chalchuapa, El Salvador, revealed the structure to have been a multiple-episode Late Preclassic burial mound. The skeletal remains of 33 individuals were found in the construction fill. These remains are interpreted as evidence for human sacrifice. Osteological analysis was performed with the skeletal materials in situ. The individuals whose sex could be determined were adult males. This and other evidence suggests that the E3-7 burials might have been war captives from a “foreign” (non-Chalchuapa) population.
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