Gaussian Process Regression and Bayesian Model Averaging: An Alternative Approach to Modeling Spatial Phenomena

Gaussian Process Regression (GPR) is a nonparametric technique that is capable of yielding reliable out‐of‐sample predictions in the presence of highly nonlinear unknown relationships between dependent and explanatory variables. But in terms of identifying relevant explanatory variables, this method is far less explicit about questions of statistical significance. In contrast, more traditional spatial econometric models, such as spatial autoregressive models or spatial error models, place rather strong prior restrictions on the functional form of relationships, but allow direct inference with respect to explanatory variables. In this article, we attempt to combine the best of both techniques by augmenting GPR with a Bayesian Model Averaging (BMA) component that allows for the identification of statistically relevant explanatory variables while retaining the predictive performance of GPR. In particular, GPR‐BMA yields a posterior probability interpretation of model‐inclusion frequencies that provides a natural measure of the statistical relevance of each variable. Moreover, while such frequencies offer no direct information about the signs of local marginal effects, it is shown that partial derivatives based on the mean GPR predictions do provide such information. We illustrate the additional insights made possible by this approach by applying GPR‐BMA to a benchmark BMA data set involving potential determinants of cross‐country economic growth. It is shown that localized marginal effects based on partial derivatives of mean GPR predictions yield additional insights into comparative growth effects across countries.     

Ruwayda: an historic urban settlement in north Qatar

SUMMARY: Ruwayda was first identified as an archaeological site in the 1970s and was excavated between 2009 and 2014. Despite a paucity of documentary evidence, this large settlement, which extends over an area of more than 90 hectares, contains a number of features indicative of an urban settlement including two mosques, a series of warehouses, a large multi-period fort, large courtyard houses interspersed with smaller, less substantial structures and a number of cemeteries. In addition to these buildings, there is also evidence for associated field systems and a walled garden.     

The history of econometric ideas. Historical perspectives in modern economics

This article presents a comparative analysis of the concepts of totalitarian democracy and positive liberty in the work of Jacob Leib Talmon and Isaiah Berlin. Its main purpose is to show that a combined analysis of Talmon and Berlin's biographical relationship and their individual texts demonstrates that Talmon's idea of totalitarian democracy may have had a greater influence on Berlin's notion of positive liberty than Berlin seems to have ever acknowledged. The article first summarises the intellectual and biographical relationships that tied these two authors together in a personal friendship and an intellectual fellowship that lasted for more than three decades. In the second part, the insights drawn from the investigation of the authors' intellectual and biographical relationships are linked to an analysis of their texts, The Origins of Totalitarian Democracy and Two Concepts of Liberty. Finally, in the third part of the article, three crucial aspects of Talmon's definition of totalitarian democracy are considered: the interpretation of the Enlightenment and Rousseau's thought, the view of the French revolution, and the possible impact each of these has on subsequent Marxist and socialist reflection, to see how they are addressed in Berlin's idea of positive liberty.     

The Landes de Gascogne (southwest France): periglacial desert and cultural frontier during the Palaeolithic

During the last glacial period, a large part of the Aquitaine basin (southwest France) was a periglacial desert comprising coversands with low-relief dune fields surrounded by loess accumulations. OSL and radiocarbon dates show that the phase of maximum sand deposition coincides with Marine Isotope Stage (MIS) 2. Peats and gleyic palaeosoils intercalated within the sands at some sites indicate that vegetation cover was able to develop locally during short events, possibly D–O interstadials, due to raised groundwater levels in interdunal depressions. Few Palaeolithic sites have been discovered in the coversand area in contrast to the peripheral loess region. Systematic survey along a future highway corridor demonstrates that this paucity of sites is not the result of insufficient survey nor deep site burial, but rather reflects an archaeological reality. This strongly suggests that the sand area was not attractive for hunter–gatherer populations due to its reduced levels of water resources, and available vegetation and animal biomass. The distribution of cultural markers such as art items and projectile points also shows that the coversand area probably acted as a barrier separating two different cultural sub-areas, one in the Pyrenees and Cantabria, the other in the Périgord. As a consequence, the commonly accepted view that southwest France, as a whole, served as a refugia during the cold and arid phases of the Pleistocene should be replaced by a more complex one that reflects the fact that a large part of the territory was almost unoccupied and that human populations were concentrated along alluvial valleys.     

On the tracks of the earliest dinosaurs: implications for the hypothesis of dinosaurian monophyly

From the record of dinosaurian skeletal remains it has been inferred that the origin and initial diversification of dinosaurs were rapid events, occupying an interval of about 5 million years in the Late Triassic. By contrast numerous reports of dinosauroid tracks imply that the emergence of dinosaurs was a more protracted affair extending through much of the Early and Middle Triassic. This study finds no convincing evidence of dinosaur tracks before the late Ladinian. Each of the three dinosaurian clades — Theropoda, Sauropodomorpha, Ornithischia — produced a unique track morphotype that appears to be an independent modification of the chirotherioid pattern attributed to stem-group archosaurs (thecodontian reptiles). The existence of three divergent track morphotypes is consistent with the concept of dinosaurian polyphyly but can be reconciled with the hypothesis of dinosaurian monophyly only by invoking many and rapid reversals in the locomotor anatomy of early dinosaurs. The origin of dinosaurs was not the correlate or consequence of any single event or process, be it global change, competitive replacement, or opportunism in the wake of mass extinction. Instead the origin of dinosaurs is envisaged as a series of three cladogenetic events over an interval of at least 10 million years and possibly as much as 25 million years. This scenario of dinosaurian polyphyly is as well-supported by fossil evidence as is the currently favoured view of dinosaurian monophyly.     

Poromoi Tamu and the Case of the Drowning Village: History, Lost Places and the Stories We Tell

Archaeological excavations at an ancestral village site within rainforest in Papua New Guinea has revealed buried cultural evidence that can be explained in a number of ways. While interpretations based on Western archaeological methods suggest regional landscape dynamics informed by geomorphological processes, Indigenous Rumu oral traditions suggest an interpretation of the site’s stratigraphy based on the workings of spiritual forces. The role of story-telling and new information in site interpretation and understanding is explored in light of these different yet complementary accounts.