Model Uncertainty in Matrix Exponential Spatial Growth Regression Models

This article considers the most important aspects of model uncertainty for spatial regression models, namely, the appropriate spatial weight matrix to be employed and the appropriate explanatory variables. We focus on the spatial Durbin model (SDM) specification in this study that nests most models used in the regional growth literature, and develop a simple Bayesian model‐averaging approach that provides a unified and formal treatment of these aspects of model uncertainty for SDM growth models. The approach expands on previous work by reducing the computational costs through the use of Bayesian information criterion model weights and a matrix exponential specification of the SDM model. The spatial Durbin matrix exponential model has theoretical and computational advantages over the spatial autoregressive specification due to the ease of inversion, differentiation, and integration of the matrix exponential. In particular, the matrix exponential has a simple matrix determinant that vanishes for the case of a spatial weight matrix with a trace of zero. This allows for a larger domain of spatial growth regression models to be analyzed with this approach, including models based on different classes of spatial weight matrices. The working of the approach is illustrated for the case of 32 potential determinants and three classes of spatial weight matrices (contiguity‐based, k‐nearest neighbor, and distance‐based spatial weight matrices), using a data set of income per capita growth for 273 European regions.     

792 or 793? Charlemagne’s canal project: craft,nature and memory

In autumn 793, Charlemagne visited the fossatum magnum (the ‘big ditch’ or canal) between the Rhine and Danube. Excavations, dendrochronology and a re‐reading of Carolingian Annals shed new light on the chronology and setting of this canal, which was planned in 792, initiated in 793, and abandoned later that year. The abandonment is attested by both written and archaeological evidence. The different versions of the annals offer a unique opportunity for comparison with the archaeological record. Evidence that works of Vitruvius circulated in the Carolingian court suggests that Charlemagne’s advisers were drawing on classical tradition when they pitched the idea of digging the canal.     

An Umm an‐Nar culture stone bas‐relief from Al‐Qutainah,Sultanate of Oman

The Al‐Qutainah stone with its bas‐relief decoration was found in a secondary position, reused through time. The object is clearly a facing stone, originally part of an Umm an‐Nar period tomb, and was subsequently repeatedly reused for making new engravings. While working out the sequence of images it became clear that the very first image was a pair of human figures. This artwork is associated to grave architecture and therefore dates to the Umm an‐Nar period. Two models of interpretation can be suggested, the image of a human pair or the image of a supplicant and deity. Changes in the original meaning of the image indicate conceptual changes in subsequent periods, most probably alterations in the underlying social structure. The importance of the Qutainah stone is not solely due to rare monumental human figurative expression of the period in Oman; furthermore, the find spot in the Adam region is at a distance from the central location of Umm an‐Nar culture that has so far emerged.     

Age determination of Petra's engineered landscape – optically stimulated luminescence (OSL) and radiocarbon ages of runoff terrace systems in the Eastern Highlands of Jordan

The unfavourable mountainous environment of the Petra region in southern Jordan was modified by ancient engineers to supply the Nabataean/Roman city of Petra with food and water. The area was reclaimed by installing extended runoff terrace systems and hydraulic structures. The agricultural terrace systems have so far been dated based on surface pottery, and the chronology of the systems is under debate. In this study, optically stimulated luminescence (OSL) and radiocarbon dating techniques were successfully applied to date these terrace systems. Samples were taken from the fills of agricultural terraces and underneath their walls to determine the chronology of the construction, use and abandonment of the agricultural terraces. The results suggest that runoff farming in the Petra region started around the beginning of the Common Era, and construction, use and maintenance lasted at least until 800 AD.     

From “Spitsbergen” to “Svalbard”. Norwegianization in Norway and in the “Norwegian Sea”, 1820–1925

Abstract

The aim of the paper is to enhance our understanding of the Norwegian acquisition of Spitsbergen/Svalbard by using the concept of Norwegianization as a tool for analyzing the political and diplomatic background for the Spitsbergen treaty of 1920, and comparing the Norwegianization polar politics with the Norwegianization concept used to analyze the internal colonization in the Sami districts of northern Norway during the same period. The paper concludes that the politics of Norwegianization on the main islands in the North Ocean – renamed the Norwegian Sea by Norwegian oceanographers in the 1870s – was an offensive policy of expansionism, motivated by historical and geographical considerations and alleged rights to re-establish the Medieval Norse empire.     

Optical dating of alluvial deposits at the orogenic front of the andean precordillera (Mendoza,Argentina)

Well constrained numerical ages of alluvial fan sediments are key to understanding the chronology of alluvial episodes and tectonic activity at the front of the Andean Precordillera. We tested the application of radiocarbon and optically stimulated luminescence (OSL) dating in the distal part of an alluvial fan five kilometers north of Mendoza. For OSL dating a large number of aliquots (n > 70) — each composed of ∼50 quartz grains — were measured in order to obtain reliable burial ages despite scattered dose distributions. Owing to a feldspar contamination in all samples, an infrared stimulation was inserted before each OSL measurement, which reduced the feldspar OSL signal successfully. By using the minimum age model we obtained stratigraphically consistent burial ages of alluvial deposits in a depth profile. The uppermost ∼1 m of sediment is composed of debris flow deposits buried 770±76 years ago. Three plant remnants used for radiocarbon dating from the same layer, however, yielded ages younger than 350 years, which are interpreted to underestimate the depositional age. Underneath the debris flow, a major unconformity cuts a series of distal alluvial fan sediments with interstratified floodplain deposits, which are composed of sandy and calciterich silt layers, respectively. Three samples from this unit which were distributed over one meter of sediment thickness yielded statistically concordant OSL ages of 12.3±1.2 ka, 12.3±1.2 ka, and 11.7±1.1 ka. The deposition of these sediments during the latest Pleistocene coincides with a phase of cool and humid climate, which occurred before the alluvial fan propagated farther into the foreland. The overlying debris flow sediments are associated with alluvial fan incision during the arid Late Holocene.     

Dividing Homer (continued): Innovation vs. Tradition in Homer - an Overlooked Piece of Evidence

In Homeric studies, the evidence of metrics has often been overlooked. The authors argue that the hexameter must be a recent development, closely bound up with the transition from an Aeolic to a Ionic phase in the development of the epic diction. The Ionic phase must have been very short, and the rise of the Iliad is probably also to be situated at the very moment of change in meter and dialect.