We present reservoir effects on shells of species Terebralia palustris and Marcia spp. that were recovered during archaeological excavations at the multi-period site of Tell Abraq, Sharjah Emirate, UAE (This paper was presented at the combined 24th Radiocarbon and 10th Radiocarbon & Archaeology International Conference, Zurich, Switzerland, Sept. 2022.). The site was inhabited during the mid to late Holocene. It is situated in a lagoonal environment with former mangrove forests at the Arabian Gulf coast of southeast Arabia. Due to availability in the immediate proximity, shellfish played an important role for the local subsistence throughout the site’s occupation. Tell Abraq provides a well-defined and stratigraphically controlled archaeological context for investigations on the reservoir effect of the two species chosen. Crucial for the determination of the marine reservoir effect is comparison with contemporaneous terrestrial carbon samples. We discuss the data in a wider context with respect to results obtained at other sites.

We have investigated the possibility of direct accelerator mass spectrometry radiocarbon (AMS 14C) measurement of carbonate samples at ANSTO using the STAR 2 MV tandem accelerator. Each carbonate sample was powdered, mixed with metal powder and pressed into an aluminum cathode for direct carbonate measurement by AMS 14C. Of the three high-purity metal powders (Fe, Nb, and Ag) used in our investigation, Nb was found to be the best metal, which delivered higher carbon beam currents and lower background. Beam currents for targets containing the optimal carbonate mass of 1.5–2.0 mg were ∼8% of those obtained from graphite targets of standard size (>0.5 mg C). Typical measured blank for Carrara marble (IAEA-C1) of ∼40 ka was obtained. Background-corrected 14C values of carbonate targets agreed well with their associated values obtained from high-precision analysis of graphite targets within 2σ uncertainties. Typical precision of this rapid AMS analysis was ∼1% for samples <8 ka. Despite lower precision for carbonate target ages (compared to standard graphite target ages), these ages are useful for palaeobiological applications where a large number of dates are required, such as time-averaging studies.

The imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.

The analyses of work traces in the shell objects found in the offerings of the Great Temple of Tenochtitlan, by scanning electron microscopy (SEM), has allowed to find an important group of objects made locally in Tenochtitlan. These shell pieces have been found in the constructive stages IVb to VII (1469-1520). Recently, another groups of objects have been found that present different work traces and that seems to be foreign productions. In this paper this new data will be presented and it will be discuss the possible origin of the objects.

In four offerings of the Great Temple of Tenochtitlan five groupings of Pinctada Mazatlanica shell pendants were found. Due to the burial conditions, damages on the surfaces can be observed in almost all the objects. In order to assess the deterioration degree, we used a visible light spectrometer. This is an inexpensive method to determine qualitatively the reflectance of the light at the surface that is directly related to the amount of organic material remains in these objects. This data may be used as a conservation marker for monitoring the collection and it can provide outstanding information to preserve the fragile shell pendants using a non-destructive method.

The morphostructures of larval and juvenile shells of two common species of bivalves of the north-western Sea of Japan, Mytilus trossulus and Crenomytilus grayanus have been examinated. Two types of morphological features were identified on the basis of the results obtained and comparison with materials of other species of the subfamily Mytilinae. One group of morphological features (absence or presence of the nepioconch; form and size of posterior lateral teeth) characterizes the higher taxonomic categories, while the other one (morphological details of general outline of the secondary prodissoconch and juvenile shell; ratio shell height/length; form, size and number of provincular and additional teeth; number of posterior lateral teeth, and others) serves to separate taxa of the generic or specific ranks.

The present paper proposes and analyzes a general locking free mixed strategy for computing the deformation of incompressible three dimensional structures placed inside flexible membranes. The model involves as in Chapelle and Ferent [Math. Models Methods Appl. Sci.13 (2003) 573–595] a bending dominated shell envelope and a quasi incompressible elastic body. The present work extends an earlier work ofArnold and Brezzi [Math Comp.66 (1997) 1–14] treating the shell part and proposes a global stable finite element approximation by coupling optimal mixed finite element formulations of the different subproblems by mortar techniques. Examples of adequate finite elements are proposed. Convergence results are derived in two steps. First a global inf-sup condition is proved, deducedfrom the local conditions to be satisfied by the finite elements used for the external shell problem, the internal incompressible 3D problem, and the mortar coupling, respectively. Second, the analysis ofArnold and Brezzi [Math. Comp.66 (1997) 1–14] is extended to the present problem and least to convergence results for the full coupled problem, withconstants independent of the problem's small parameters.

We consider a model problem (with constant coefficients and simplified geometry) for the boundary layer phenomena which appear in thin shell theoryas the relative thickness ε of the shell tends tozero. For ε = 0 our problem is parabolic, then it is amodel of developpable surfaces. Boundary layers along and across the characteristichave very different structure. It also appears internal layers associatedwith propagations of singularities along the characteristics. The specialstructure of the limit problem often implies solutions which exhibitdistributional singularities along the characteristics. The correspondinglayers for small ε have a very large intensity. Layers alongthe characteristics have a special structure involving subspaces; thecorresponding Lagrange multipliers are exhibited. Numerical experimentsshow the advantage of adaptive meshes in these problems.