Measuring Frictional Costs in E-Commerce: The Case of Name-Your-Own-Price Auctions

Frictional costs are defined as the disutility related to the conduct of an online transaction. Thus,frictional costs can accrue through the consumer‘s decision-making process prior to an onlinetransaction, e.g., bidding in interactive pricing mechanisms like auctions. We present two models forthe measurement of frictional costs in Name-Your-Own-Price auctions where these costs can either bemeasured through a discount factor or in absolute values. We compare the fit and estimation results ofthese models by analyzing bidding data from a German NYOP seller. Our results show that bothmodels are equally parsimonious, explain a comparable fraction of variance and both models yieldrobust and reasonable parameter estimates

Unsupervised Classification of Neolithic Pottery From the Northern Alpine Space Using t-SNE and HDBSCAN

Terms of “Neolithic cultures” are still used to describe spatial and temporal differences in pottery styles across central Europe. These terms date back to research periods when absolute dating methods were lacking and typological classification was used to establish chronologies. Those terms are charged with problematic, biasing notions of social configurations: cultural homogeneity, spatial boundedness, and immobility. In this article, we present an alternative approach to pottery classification by using ceramics from dendrochronologically and C14-dated sites of the 40th–38th c. BC located in the northern Alpine Foreland. The newly developed methodology uses a computational unsupervised classification based on profile shape and additional nominal characteristics using t-Distributed Stochastic Neighbour Embedding and Hierarchical Density-Based Spatial Clustering of Applications with Noise for cluster analyses. Its role in our project was to provide a quantitative, algorithm-based approach to classify large datasets of pottery while simultaneously account for a large number of variables. This enabled us to find similarity structures that would escape human cognitive capacities on which typological classification is based on. It formed one pilar of a mixed method research approach combining qualitative and quantitative methods of pottery classification. Our results show that the premises of cultural homogeneity are untenable but can be methodologically overcome by using the proposed classification approaches

Epilithic diatoms (Bacillariophycae) from streams in Ramsar, Iran

Epilithic diatoms were identified from five small streams and one canal in Ramsar, northwest Iran. Atotal of 155 diatom taxa belonging to 37 genera were found and only two species remained unidentified (Fragilaria sp. and Nitzschia sp.). Achnanthes, Nitzschia, Navicula, Cocconeis, Melosira, Amphora, Craticula, Diatoma, Surirella, Cymbella, Diploneis and Entomoneis were among the most abundant genera. Eighty seven taxa were recorded for the first time in Iran. Thirty two of the genera belong to the Pennales and 5 to the Centrales. Species richness was rather high ranging from 66 to 95 taxa at the six sites studied. The epilithic diatom species found in Ramsar were dominated by cosmopolitan taxa found in meso- to fairly eutrophic waters with high conductivity and high nutrient concentrations. The abundances found at all six sites were compiled in order to estimate the overall abundance of each taxon in Ramsar. This study includes EM pictures of diatoms observed in Ramsar, Iran

Territoriale und soziale Strukturen. Modelle zur Kollektivgrabsitte der Wartberg-Gruppe

The element identity is regarded as the reason for the monumental erection of collective burials.Estimations of the labour costs for the graves as well as calculations of the living population show that the associated society could have been much smaller than usualy thought. For the only well investigated contemporary settlement (Wittelsberg, Kr. Marburg-Biedenkopf) for example can a much larger population be expected. Anthropological Investigations show a distribution of ages and sex which do not imply an exclusive access to the burial site. The graves themselve are according to GIS-analysis grouped in small clusters in constant distance. Radiocarbon dating shows that at least some of the grouped graves where erected at the same time.Because of these results a model of the burying society can be build which organised themselve according to ancestry (lineage) in oposition to the usual interpretation as territorial markers of regional comunities. Ethnological researches underpin this model. In all recent collective burying societies the access to a grave is controled by descent

Pose Normalization of Indoor Mapping Datasets Partially Compliant with the Manhattan World Assumption

In this paper, we present a novel pose normalization method for indoor mapping point clouds and triangle meshes that is robust against large fractions of the indoor mapping geometries deviating from an ideal Manhattan World structure. In the case of building structures that contain multiple Manhattan World systems, the dominant Manhattan World structure supported by the largest fraction of geometries is determined and used for alignment. In a first step, a vertical alignment orienting a chosen axis to be orthogonal to horizontal floor and ceiling surfaces is conducted. Subsequently, a rotation around the resulting vertical axis is determined that aligns the dataset horizontally with the coordinate axes. The proposed method is evaluated quantitatively against several publicly available indoor mapping datasets. Our implementation of the proposed procedure along with code for reproducing the evaluation will be made available to the public upon acceptance for publication

Mobility as resilience capacity in northern Alpine Neolithic settlement communities

Resilience has recently become an insightful conceptual framework that helps scholars explore how communities respond to external shocks, such as environmental changes. In prehistoric archaeology, this notion has primarily been investigated using the Resilience Theory (RT) and the Adaptive Cycle model (AC), developed by Gunderson and Holling, which are applied to adaptive systems in order to understand the source and role of change. However, such systems-theoretical approaches, which derive from ecology and psychology, bear the danger of leading to a top-down application of deductive models when appropriated to the fragmented archaeological sources. In other words, the risk is to assume the RT and AC model first and then to fit archaeological data within those assumptions. In this paper, we propose an alternative, inductive bottom-up approach in which we define resilience as a set of adaptive capacities grounded in social practices that enabled communities to cope with and respond to challenges. We use the Neolithic wetland sites from the Three-Lakes Region in the northern Alpine foreland of western Switzerland as a case study. These sites provide an abundance of archaeological and palaeoecological information, which can be used to examine the resilience of settlement communities to climate fluctuations. We will evaluate whether a causal relationship might have existed between climate changes in the period between 3600 and 3200 BCE and an observable decline of settlement activities on the shores of the large lakes. In addition to year-accurate reconstructions of settlement histories, we will apply statistical significance tests on archaeological and palaeoclimatic time series to question the correlation and causality between settlement activities and climate fluctuations. Besides the settlement frequency curve, we will use the radioactive beryllium-10 isotope (Be10) content in the GISP2 ice core from the Greenland Ice Sheet and the δ18O values of well-dated speleothems as proxies for temperature and precipitation, respectively. The inferred hypothesis, i.e. that periodically rising lake levels led to the flooding of former inhabitable spaces on the lakes’ shore zones and forced communities to relocate their settlements to the hinterland, will further be tested. Therefore, we apply multivariate statistics to pollen data to evaluate human influence on vegetation (land clearing) taken as settlement activity beyond the shores of large lakes. In addition, we examine the relevance of transformations in pottery styles as further indicators for spatial mobility