The intuitions of higher dimensional algebra for the study of structured space

Higher dimensional algebra frees mathematics from the restriction to a purely linear notation, in order to improve the modelling of geometry and so obtain more understanding and more modes of computation. It gives new tools for noncommutative, higher dimensional, local to global problems, through the notion of «algebraic inverse to subdivision». We explain the way these ideas arose for the writters, in extending first the classical notion of abstract group to abstract groupoid, in which composition is only partially defined, as in composing journeys, and which brings a spatial component to the usual group theory: An example from knot theory is used to explain how such algebra can be used to describe some structure of a space. The extension to dimension 2 uses compositions of squares in two directions, and the richness of the resulting algebra is shown by some 2-dimensional calculations. The difficulty of the jump from dimension 1 to dimension 2 is also illustrated by the comparison of the commutative square with the commutative cube-discussion of the latter requires new ideas. The importance of category theory is explained, and a range of current and potential applications of higher dimensional algebra indicated.     

Electron Microprobe Analysis of 9th–12th Century Islamic Glass from Córdoba,Spain

Twenty‐six samples from domestic assemblages of 9th–12th century Córdoba were subjected to electron microprobe analysis. The results reveal two main compositional types. The first, encountered in 13 of the samples, seems to result from the combination of plant ashes with high‐impurity sand, and has some contemporary parallels from Syria and Egypt. The second type is a lead–soda–silica glass, encountered in a relatively high proportion of the glasses (11 of the 26 sampled), possibly formed by the addition of lead metal to existing glasses and with very few known parallels. These are among a very small number of results available to date on the chemical composition of glasses from medieval Spain, and the presence of a high proportion of lead–soda–silica glasses is particularly interesting, possibly indicating a technological practice unique to, or originating in, the western Muslim world.     

Plasters from Different Buildings of the Sacred Precinct of Tenochtitlan (Mexico City): Characterization And Provenance

In this work, we present the results of the characterization of 20 lime plaster samples taken from the Sacred Precinct of Tenochtitlan (Mexico City), the ancient capital of the Aztec empire. The samples come from different buildings of this precinct (A, B and D) and from the west façade of phase VI of the Templo Mayor pyramid. The objective of the work is to characterize the plaster samples, to understand the raw materials used, and to evaluate the presence of similarities and differences among the samples in the building techniques and raw materials employed. All the samples were studied with OM, SEM–EDS and LA–ICP–MS. The study provided evidence of the plastering and replastering practice in the same constructive phases. The results of the analyses showed the existence of important similarities and differences among buildings and constructive phases in the Sacred Precinct. In order to understand the provenance of the limestone used in the plasters, the lumps and the binder of the samples were analysed. The results were compared with those of the limestone outcrops located in central Mexico. The provenance study showed that all the limestone used in the construction of the analysed buildings of Tenochtitlan's Sacred Precinct comes from the Tula region.     

THE EFFECT OF ACCESSIBILITY ON PRODUCTIVITY IN SPANISH MANUFACTURING FIRMS

This paper evaluates the impact of accessibility on the productivity of Spanish manufacturing firms. We suggest the use of accessibility indicators of workers and commodities, integrating transport, land use, and individual components, computing real distances or traveling times using the Spanish full road network. Estimated firms’ total factor productivity is explained as a function of the accessibility indicators and additional control variables. Results evidence the crucial role on firms’ productivity to the accessibility of commodities and to a slightly lesser extent the workers.     

Geoarchaeology and spatial distributions of the ‘Coche Quemado' obsidian source in north-western Patagonia

In north-western Patagonia, obsidian was used during the entire Holocene, and its importance increased with time. Recent fieldwork discovered a new obsidian source located in the Río Grande, which was called ‘Coche Quemado' (CQ). The results indicate that the CQ source has a different geochemical signal than all other sources in the region. Its use is spatially restricted to piedmont and, to a lesser extent, the plains. Chronologically, CQ was exploited in the middle and late Holocene, and its use accounts for a range of spatial distribution between 150 and 200 km.     

Altamira 1937: <Emphasis Type="Italic">Grotta Aperta—</Emphasis>Conflict Archaeology of a World Heritage Cave

This article addresses the dark and barely known side of one of the most iconic symbols of Spanish heritage: the Palaeolithic cave of Altamira (region of Cantabria). The cave is a benchmark of European rock art and was declared a World Heritage Site by UNESCO in 1985. Access to the cave’s guestbook (inaugurated on 18 August 1928 with King Alfonso XIII’s signature) has granted us the opportunity to deconstruct the hegemonic discourse therein, and to approach a time, the Spanish Civil War (1936–1939), which had been left almost without discussion in historical literature on the archaeological site. Conflict Archaeology can cast light on this unknown reality and raise controversial and contentious issues about the Altamira cave and its role as a wartime cultural asset during the war.     

First record of a fossil selenariid bryozoan in South America

López-Gappa, J., Pérez, L.M. & Griffin, M. February 2017. First record of a fossil selenariid bryozoan in South America. Alcheringa XX, xxx-xxx. ISSN 0311-5518.

Selenariidae Busk 1854 (Bryozoa) is considered endemic to Australia and New Zealand. Here we describe a new species of Selenaria Busk 1854 from the lower Miocene Monte León Formation (Patagonia, Argentina). Selenaria lyrulata sp. nov. is characterized by autozooids with a lyrula-like, anvil-shaped cryptocystal denticle, opesiular indentations and lateral condyles, as well as avicularia with a shield of fused costae. This is the first record of a selenariid bryozoan in South America.

Juan López-Gappa [lgappa@macn.gov.ar] CONICET—Museo Argentino de Ciencias Naturales. Av. Ángel Gallardo 470, C1405DJR, Ciudad Autónoma de Buenos Aires, Argentina; Leandro Martín Pérez [pilosaperez@gmail.com] and Miguel Griffin [patagonianoyster@gmail.com], CONICET—División Paleozoología Invertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina.