Radon Predictions with Geographical Information System Covariates: From Spatial Sampling to Modeling

Radon (Rn) is a potentially toxic gas in soil which may affect human health. Assessing Rn levels in soil gas usually requires enormous efforts in terms of time and costs, since the sampling protocol is very complex. In most cases, the variable under study is sparsely sampled over the domain and this could affect the reliability of the spatial predictions. For this reason, it is useful to incorporate, into the estimation procedure, some auxiliary variables, correlated with the in soil gas Rn concentrations (primary variable) and more densely available over the domain. On the basis of this latter aspect, it is even better if the covariates are derived from a geographical information system (GIS). In this article, the Rn sampling protocol used during a measurement campaign planned over a risk area is described and the process of deriving GIS covariates considered as secondary information for predicting the primary variable is clarified. Then, multivariate modeling and prediction of the Rn concentrations over the domain of interest are discussed and a comparative study regarding the performance of the prediction procedures is presented. Rn prone areas are also analyzed with respect to urban and school density. All these aspects can clearly support decisions on environmental and human safeguard.     

The circulation of precious metals in the Arab Empire: the case of the near and the Middle East*

The analysis by nuclear activation techniques and by inductively coupled plasma mass spectrometry combined with an UV laser of a large number of gold coins issued in the Arab Empire from the seventh to the 12th century ad showed that several different supplying sources were used, according to the region and to the period. The aim of this paper is to point out the circulation of gold in the Near and Middle Eastern mints of the Arab Empire and to make a parallel with the mints’ policies running in the other regions of the Empire, such as North Africa, the Iberian Peninsula and the Sicily. The identification of different gold ores by means of characteristic trace elements indicated recycling of the ancient coinage and, after ad 750, the minting in the entire Arab Empire of different new gold ores: Egyptian type, North Eastern type and West African type. The analysis of a small number of silver coins from the same periods and regions also showed a change in the ore supply after ad 750.     

3D electrical prospection in the archaeological site of El Pahñú, Hidalgo State,Central Mexico

The implementation of a 3D Electrical Resistivity Tomography (ERT-3D) survey was carried out in El Pahñú archaeological site, Hidalgo State, Central Mexico. A combination of a new ERT arrays allowed studying the subsoil beneath the Main Pyramid built near the edge of a plateau, along with another important structure (the Tecpan), which was a smaller structure that lodged the governmental council in pre-Hispanic times. The recorded information was acquired through the combination of several electrodic designs: L-Corner (LC), Equatorial (Eq), and Minimum Coupling (MC). For the Main Pyramid, the electrodes were set up around the perimeter of the structure, since they were not permitted to be inserted over the edifice, thus preventing damages to the architectonic elements. The second structure allowed inserting electrodes on selected spots within the architectonic space. The combination of the different arrays made possible the acquisition of 1204 apparent resistivities beneath the Main Pyramid and 2460 resistivity data beneath the Tecpan. The apparent resistivity data were inverted to obtain a three dimensional display of the subsoil electrical resistivity beneath the archaeological structure. The interpreted resistivity model under the Main Pyramid displayed a highly resistive structure towards its northern face that could be associated with infill. Such material was employed by the ancient constructors to level the terrain close to the edge of the cliff. Another interesting anomaly was found towards the central portion of the structure that could be associated to a foundation offer. The interpretation of data beneath the Tecpan identified the structural foundations and other interesting anomalies related to the different occupational times. The investigation supported the archaeological investigation of the site, suggesting areas of potential geological risk and of archaeological interest. For example, the Main Pyramid presents serious stability problems, indicating that the infill has weakened, producing cracks threatening long-term pyramid integrity.     

First Trials to Set Up a Microwave Reflectometric Tool for the Survey of Historic Timber Structures

Timber structures can be degraded during their life both by structural problems and by biological degradation factors like fungi and insects. The occurrence of those biodegradation agents could lead to a loss of their structural integrity, in the absence of appropriate maintenance. An early assessment of the decay is even more important when the wooden structures are part of historical buildings, in the interest of conservation of cultural heritage.

This article presents an application of microwave reflectometry for the in situ evaluation of timber structures. The measurement system allows detecting anomalies inside the material in a non-destructive and non-invasive manner.

The reflection coefficient is measured by means of a vector network analyzer (VNA) using a double-ridge antenna which transmits the continuous-wave (CW) microwave signal and receives the signal reflected by the material under investigation.

Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its possible usefulness during the diagnostic phase as a non-invasive tool for preliminary screening.     

Chemical tracers of Lusitanian amphorae kilns from the Tagus estuary (Portugal)

In this paper, the characterization of Roman amphorae from the Porto dos Cacos (PC) and Quinta do Rouxinol (QR) workshops, in the Tagus estuary, dating to a period between the 1st and 5th century AD was carried out on the basis of instrumental neutron activation analysis data on 260 amphorae fragments, together with mineralogical compositional studies obtained by X-ray diffraction.     

Flake scar patterns of Clovis points analyzed with a new digital morphometrics approach: evidence for direct transmission of technological knowledge across early North America

Clovis points are the principal diagnostic artifacts of a Clovis complex that spread across North America between ca. 11,050–10,800 radiocarbon years before present. Clovis may be the best documented Paleoamerican culture in North America, but much remains to be learned about the movement and interactions of Clovis peoples. Similarities among Clovis points from geographically diverse locations have led some researchers to suggest that a uniform projectile point technology existed across North America during Clovis times. Others have rejected this idea, proposing local and independent technological adaptations to different regional environments. To investigate these ideas, we used digital morphometrics to analyze 50 Clovis points from nine different contexts. First, 3D surface models of the points were created with a portable laser scanner. Next, these models were digitally cross-sectioned through both faces, yielding two-dimensional isoheight contours of flake scar patterns that reflect the original reduction techniques used to shape the projectile points. In the final step, the contours were transformed with elliptic Fourier analysis into Fourier coefficient series, and patterns of variation and symmetry were explored with principal components analysis. When compared to modern Clovis point replicas made by an expert knapper, the flake scar contours of the ancient Clovis points showed little morphological variation and a large degree of bifacial symmetry. Our results support the existence of a widespread standardized “Clovis” knapping technique, most likely transmitted through direct interaction between knappers from different groups.     

Local culture as a context for entrepreneurial activities

This paper examines how an industrial legacy leads to the formation of a distinct local culture and how the culture’s survival provides a context for the subsequent entrepreneurial activities in new local industries. The discussion about culture as a key driver of entrepreneurship and economic growth is well established in the academic debate. However, we know little about how culture is formed. Through a qualitative case study of two polar Swedish cities, the study highlights four key factors which are instrumental in the formation of local culture: initial conditions, characteristics of key players, network activities and composition of newcomers. We show how the local entrepreneurs responded to the underlying assumptions of the two different cultures.     

The “Hidden” Code: Coding and Classifying in Rock Art. The Case of Northwestern Patagonia

In spite of its importance for rock art studies, rock art motifs coding and classification process is not always made explicit. In this discussion of the process of rock art classification, we consider an exploratory research employing two different criteria for the coding of a northwestern Patagonian rock art motifs database. One coding makes use of a ‘lumping’ criterion, and the other uses a ‘splitting’ criterion. Each of these criteria will be evaluated using cladistic analysis, recording how each coding criterion affects results. As a conclusion, and given our results, the use of more than one coding criterion is suggested when classifying rock art.