A Spatial Mixture Model of Innovation Diffusion

The diffusion of new product or technical innovation over space is here modeled as an event‐based process in which the likelihood of the next adopter being in region r is influenced by two factors: (i) the potential interactions of individuals in r with current adopters in neighboring regions, and (ii) all other attributes of individuals in r that may influence their adoption propensity. The first factor is characterized by a logit model reflecting the likelihood of adoption due to spatial contacts with previous adopters, and the second by a logit model reflecting the likelihood of adoption due to other intrinsic effects. The resulting spatial diffusion process is then assumed to be driven by a probabilistic mixture of the two. A number of formal properties of this model are analyzed, including its asymptotic behavior. But the main analytical focus is on statistical estimation of parameters. Here it is shown that standard maximum‐likelihood estimates require large sample sizes to achieve reasonable results. Two estimation approaches are developed which yield more sensible results for small sample sizes. These results are applied to a small data set involving the adoption of a new Internet grocery‐shopping service by consumers in the Philadelphia metropolitan area.     

Fluid evolution along multistage composite fault systems at the southern margin of the Lower Palaeozoic Anglo-Brabant fold belt, Belgium

Mineralised vein systems have been investigated at nine localities at the southern margin of the Anglo‐Brabant fold belt in Belgium. During the late Silurian to early Middle Devonian Caledonian orogeny, shear zones formed, inferred to be associated with granitoid basement blocks in the subsurface. The circulation of a metamorphic fluid, possibly originating in the Cambrian core of the fold belt, along these shear zones resulted in the formation of mesozonal orogenic mineralisation at the southern margin of the Anglo‐Brabant fold belt. The fluid had a composition dominated by H₂O–CO₂–X–NaCl–KCl. The shear zones form part of a greater fault zone, the Nieuwpoort–Asquempont fault zone, which is characterised by normal faulting that started before the Givetian and by the reactivation of the shear zones. Two fluid generations are associated with this normal faulting. First, a low salinity H₂O–NaCl(–KCl) fluid migrated through the Palaeozoic rocks after the Silurian. Based on the isotopic composition, this fluid could be a late‐metamorphic Caledonian fluid or a younger fluid that originated from the Rhenohercynian basin and interacted with Lower Devonian rocks along its migration path. Second, a high salinity H₂O–NaCl–CaCl₂ fluid was identified in the fault systems. Similar fluids have been found in southern and eastern Belgium, where they produced Mississippi Valley‐type Zn–Pb deposits. These fluids are interpreted as evaporative brines that infiltrated the Lower Palaeozoic basement, from where they were expelled during extensional tectonism in the Mesozoic.     

Human ecological niches and ranges during the LGM in Europe derived from an application of eco-cultural niche modeling

We apply eco-cultural niche modeling (ECNM), an heuristic approach adapted from the biodiversity sciences, to identify habitable portions of the European territory for Upper Paleolithic hunter-gatherers during the Last Glacial Maximum (LGM), circumscribe potential geographic extents of the Solutrean and Epigravettian technocomplexes, evaluate environmental and adaptive factors that influenced their distributions, and discuss this method's potential to illuminate past human–environment interaction. Our ECNM approach employed the Genetic Algorithm for Rule-Set Prediction (GARP) and used as input a combination of archaeological and geographic data, in conjunction with high-resolution paleoclimatic simulations for this time frame. The archaeological data consist of geographic coordinates of sites dated by Accelerator Mass Spectrometry to the LGM and attributed to the Solutrean and Epigravettian technocomplexes. The areas predicted by ECNM consistently outline the northern boundary of human presence at 22,000–20,000 cal BP. This boundary is mainly determined by climatic constraints and corresponds well to known southern limits of periglacial environments and permafrost conditions during the LGM. Differences between predicted ecological niches and known ranges of the Solutrean and Epigravettian technocomplexes are interpreted as Solutrean populations being adapted to colder and more humid environments and as reflecting influences of ecological risk on geographic distributions of cultures.     

Enrolling the Private Sector in Community Development: Magic Bullet or Sleight of Hand?

The role of the private sector in international development is growing, supported by new and evolving official programmes, financing, partnerships and narratives. This article examines the place of the private sector in ‘community development’ in the global South. It situates corporate community development (CCD) conceptually in long‐standing debates within critical development studies to consider the distinct roles that corporations are playing and how they are responding to the challenges and contradictions entailed within ‘community development’. Drawing on field‐based research across three different contexts and sectors for CCD in Fiji, Papua New Guinea and South Africa, the article suggests that caution is required in assuming that corporations can succeed where governments, non‐governmental organizations (NGOs) and international development organizations have so often met with complex challenges and intractable difficulties. We argue that four specific problems confront CCD: (a) the problematic ways in which ‘communities’ are defined, delineated and constructed; (b) the disconnected nature of many CCD initiatives, and lack of alignment and integration with local and national development planning policies and processes; (c) top‐down governance, and the absence or erosion of participatory processes and empowerment objectives; (d) the tendency towards highly conservative development visions.     

Erosive osteoarthritis in a medieval skeleton

In human skeletons from archaeological sites, osteoarthritis is by far the most common disease found, but no case of erosive osteoarthritis has been described and we present here what we believe to be the first such case.