Ancient tin production: Slags from the Iron Age Carvalhelhos hillfort (NW Iberian Peninsula)

Provenance and production of tin in the Ancient World has since long been a major topic of discussion among archaeologists. In Western Europe, where significant tin ore (cassiterite) deposits are known, only a few remains of ancient tin production, such as tin slags, have been detected. In the present work, elemental and microstructural analyses by WDXRF, SEM-EDS and XRD were performed on recently recognised tin slags from the Iron Age Carvalhelhos hillfort located in NW Iberia, a territory that represents the largest extension with tin mineralisation in Western Europe. Elemental and microstructural characterisation of cassiterite collected in a pilot field survey in the region of the hillfort are presented and discussed, as well as two ceramic fragments that could be part of a smelting structure and an iron slag from the settlement. Results show that the tin slags have variable but high contents in Sn, similarly to Pre-Medieval tin slags found in other Western European areas, but also high contents of Ta and Nb, which specifically distinguish them from other tin slags, such as those found in SW Britain. Tin ores from the hillfort region frequently have Ta and Nb in cassiterite solid solution or as inclusions of columbite group minerals, relating well with the Carvalhelhos tin slags. Up to present, the Carvalhelhos slags are amongst the very few ancient tin slags known in Western Europe, and their study can contribute to a better knowledge on ancient tin sources and trade routes

In situ transformation and cleaning of tin-drop contamination on mirrors for extreme ultraviolet light

Tin-drop contamination was cleaned from multilayer-coated mirrors by induction of phase transformation. The {\beta} - {\alpha} phase transition of tin was induced to initiate material embrittlement and enable facile removal of thick tin deposits. The necessary steps were performed under high-vacuum conditions for an in-situ demonstration of the removal of severe tin contamination from optics used for reflection of extreme ultraviolet light. Molten tin of high purity was dripped onto mirror samples, inoculated with small seed particles of gray tin and then cooled to temperatures in the range of -25 {\deg}C to -40 {\deg}C. As recorded by photographic imaging, the drops were converted in an evacuated chamber to gray tin by induction of tin pest leading to their disintegration within a few hours. They could then be easily cleaned or fell off from the surface without causing any damage of the multilayer coating. Cleaning of tin contamination from the mirrors with almost complete structural transformation of the tin drops and subsequent removal by puffs of dry gas could be achieved within a day. The fraction of area coverage of untransformed tin remaining on the samples after cleaning was evaluated from the images and generally found to be well below 1%. After tin dripping, phase transition and cleaning, analysis of the reflectance of a Mo/Si-coated mirror with measurements at wavelengths of 13.6 nm and 13.5 nm showed a reduction by only 0.5%, with an upper limit of 1%

Use of mangroves for aquaculture: Myanmar.

Aquaculture has only started to develop rapidly in the past few decades, due to better knowledge of culture species, improved methodologies and techniques in breeding, nutrition and increasing demand for food fish of high-value species such as shrimps, sea bass and groupers. Mangrove deforestation has an impact on shrimp culture itself, the success of the latter (when traditional culture method is used) depends on stocking of wild fry. For semi-intensive and intensive shrimp culture, the number of wild caught spawners may decrease because wild shrimp populations also use mangrove swamps as its feeding ground. Other negative effects of mangrove destruction to make way to shrimp ponds, include water pollution from pond effluents, sedimentation from the release of solid materials from pond, interruption of the tidal water flow, dwindling natural shrimp and fish stock due to increased pollution or product contamination due to indiscriminate use of chemicals. Chemicals and drugs (antibiotic) should not be used in fish and shrimp culture for prevention and control of bacteria and viral diseases. In order to ensure the sustainable development of aquaculture, it is important to bear in mind the interdependence of technology and natural resource under various socioeconomic setting

The Life-Cycle Motive and Money Demand: Further Evidence

This study takes a closer look at the relationship between money demand and the life-cycle motive using panel data from the Survey of Income and Program Participation. Findings indicate that the life-cycle motive exerts a direct impact on household demand for interest-earning monetary assets, but not on non-interest-earning checking deposits. The strength of the relationship, however, varies among households with divergent characteristics. There is no evidence of a unitary income elasticity for both interest- and non-interest-yielding monetary assets. The demand for interest-earning monetary assets is very sensitive to changes in the own rate of interest, but the interest rate elasticity for non-interest-earning checking accounts is quite small.life-cycle motive

Not invasive analyses on a tin-bronze dagger from Jericho. A case study

Tin-bronze makes its appearance in Southern Levant during the Early Bronze IV, the post-urban phase of the last centuries of the 3rdmillennium BC, when arsenical copper was still the most widespread copper alloy. Only from the following Middle Bronze Age tin-bronze will be the utmost spread alloy. The adoption of tin as alloying metal purports new technological skills, and a changed trade supply system, through new routes, thanks to itinerant coppersmiths. The examination of dagger TS.14.143 found in an EB IV (2300-2000 BC) tomb at Jericho by mean of trace elements and Energy Dispersive X-ray Diffraction analyses, provided info about its metal composition and technology. The detection of tin, testified only by a few specimens at the site so far, allows some reflections about the beginning of diffusion tin-bronze, and the presence of a small-scale melting activity in the post-urban phase in the key-site of Jericho

Sub-optimality of Treating Interference as Noise in the Cellular Uplink

Despite the simplicity of the scheme of treating interference as noise (TIN), it was shown to be sum-capacity optimal in the Gaussian 2-user interference channel in \cite{ShangKramerChen,MotahariKhandani,AnnapureddyVeeravalli}. In this paper, an interference network consisting of a point-to-point channel interfering with a multiple access channel (MAC) is considered, with focus on the weak interference scenario. Naive TIN in this network is performed by using Gaussian codes at the transmitters, joint decoding at the MAC receiver while treating interference as noise, and single user decoding at the point-to-point receiver while treating both interferers as noise. It is shown that this naive TIN scheme is never optimal in this scenario. In fact, a scheme that combines both time division multiple access and TIN outperforms the naive TIN scheme. An upper bound on the sum-capacity of the given network is also derived.Comment: 5 pages, 3 figures, typos correcte