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The ancient sources for the location of Thule are reviewed.1 It is suggested that the identification of the Shetland Isles as Thule was an error by Agricola. The identification was then accepted by Ptolemy, who moved Thule from the more northerly location implied by Pytheas’ account to the site of the Shetland Isles. This would account for his description of Thule/Shetland as one island. The coincident location of Ptolemy's Thule with Shetland suggests that the Roman fleet did see the islands. The emendations of Wolfson relating to Thule are examined and rejected. There is no evidence that Agricola's fleet landed in Shetland.
The in situ formation of conductive carbon lines in polymeric substrates was demonstrated by “writing” with CO2 and Nd:YAG lasers. The formation of conductive carbon lines on polymer substrates proceeds through a series of steps including; absorption of light, initiation of decomposition reactions, and thermal propagation of the pyrolysis. The effect of material composition, power density, energy density, and wavelength on the electrical resistance and morphology of the carbon lines was investigated. Above a critical laser energy density (= 400 J/cm2) sufficient light is absorbed by the substrate such that initiation of the pyrolysis reactions occurs. The decomposed polymer strongly absorbs the incident radiation and the thermal propagation of the reactions forms shiny, conductive, carbon lines. The dimensions of these lines are dependent on the energy density impinging on the polymer and are independent of the wavelengths investigated. If too high a power density is employed (∼ 104 Watts/cm2), an ablated track is formed down the center of the carbon line. This results in the relative insensitivity of the linear resistance with increasing power above 104 Watts/cm2.
The very attractive bronze figure of a horse, found in 1971 under the floor of a house in the Vindolanda vicus, has understandably become an emblem of the site on publications of the Vindolanda Trust.
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