Competitive Multifacility Location on Networks: the (r∣Xp)‐Medianoid Problem

Abstract.  We investigate the ( r ∣ X _p )‐medianoid problem for networks. This is a competitive location problem that consists of determining the locations of r facilities belonging to a firm in order to maximize its market share in a space where a competitor is already operating with p facilities. We consider six scenarios resulting from the combination of three customer choice rules (binary, partially binary, and proportional) with two types of services (essential and unessential).
Known discretization results about the existence of a solution for the set of nodes are extended. Some examples and computational experience using heuristic algorithms are presented.     

‘Guard the Good Deposit’: Technology,Provenance and Dating of Bipyramidal Iron Semi‐Products of the Durrenentzen Deposit (Haut‐Rhin,France)

In the early days of iron metallurgy in Western Europe, the most widespread type of ‘trade iron’ (semi‐product) was bipyramidal in shape. Although they are frequently found, little is known about how they were manufactured and circulated, or even about their age. An interdisciplinary approach was applied to the Durrenentzen deposit (Haut‐Rhin, France), the third‐largest in Europe in terms of artefact quantities, in an attempt to reconstruct the technological, social and economic context that caused them to be abandoned. A morphometric study of the 51 iron bars revealed a high degree of homogeneity, despite variations in detail. Four objects were selected for archaeometric studies. Metallographic analyses show internal differences (quality of the material, nature of the alloys and manufacturing techniques). Chemical analyses also showed different provenances. Finally, radiocarbon analyses of the carbon in steel (iron/carbon alloy) linked this deposit to the early Iron Age. This study provided the first benchmark for more general research, significantly changing perceptions of the economics of iron at the beginning of the Iron Age.     

Metallurgical traditions and metal exchange networks in late prehistoric central Myanmar,c. 1000 BC to c. AD 500

Myanmar has been notably underrepresented in recent studies of archaeometallurgy in Southeast Asia, despite its richness in both mineral and cultural resources and its potentially central role in long-distance exchange networks linking India, China and peninsular neighbours. Here, we present original analytical data on copper-base artefacts from several Bronze Age and Iron Age sites in Myanmar. Observed microstructures range from as-cast, worked, to fully annealed; compositions include leaded copper, low-tin to high-tin bronzes, and arsenical copper/bronze. Lead isotope analyses indicate that the metal originates from different geological sources, including several that match the lead isotope signatures of known prehistoric copper mines in Thailand and Laos. These archaeometallurgical data, including evidence for secondary copper-base production, more than double those currently available for Myanmar and document the presence of multiple local alloying and working traditions, perhaps chronologically differentiated, as well as identifying possible links to primary mineral sources across the region. Overall, this adds significant new information to the emerging picture of Southeast Asian prehistoric metallurgy at the crossroads of several major ancient cultures.     

Ground truthing of remotely identified fortifications on the Central Coast of Perú

Remote imagery, including freely available satellite images viewed in Google Earth^® and historic aerial photographs, was used to identify anomalies in a 25,000 km² macroregion encompassing 13 river valleys along the Peruvian coast. These anomalies, located atop hills and mountains, were hypothesized prehispanic fortifications. A sample of remotely identified anomalies was ground truthed in the Huaura and Fortaleza Valleys on the Central Coast of Perú. 140 positive anomalies were documented and assessed using a simple defensibility index. Our results significantly increase the number of fortifications identified in both valleys. We demonstrate the efficacy of this method for locating fortifications in a very large region to facilitate the systematic documentation of these durable indicators of warfare.     

Contribution of the resistivity method to characterize mud walls in a very dry region and comparison with GPR

Mud walls are frequent in many archaeological sites, including sites located in semi-desert regions. In cases with buried walls, the geophysical methods can be useful tools for their investigation, since they provide maps of the subsoil in a non-invasive way and in relatively short times. This article deals with the characterization of mud walls in very dry soils through the resistivity method, discussing a methodology to satisfactorily apply the method in this kind of adverse environment and how to interpret the results. The case of the Palo Blanco archaeological site, a pre-Incaic village located in the NW region of Argentina, is analyzed.     

Tiwanaku trade patterns in southern Peru

This paper provides data and analysis from an intensive settlement survey in the southwestern Titicaca Basin. This research was designed to assess the nature of Tiwanaku (AD 600–1100) long-distance trade. The survey area was placed between the prehistoric urban capital of Tiwanaku and its primary colony in Moquegua, a valley located on the Pacific watershed approximately 325 km away. The survey was specifically placed in an area where GIS analysis indicated a least-cost transit route between Tiwanaku and Moquegua. Field adjustments to the survey area were made based upon informant data about the historic location of caravan routes. The results of the survey indicate that there is a light but virtually continuous string of Tiwanaku occupation along the trails and roads in the area sampled between Tiwanaku and Moquegua. However, in contrast to the later Inca (AD 1450–1532) period pattern, Tiwanaku did not maintain way stations or build any kind of formal road system. The data indicate that Tiwanaku had indeed relied upon camelid caravans utilizing the least-cost pathways, but it did so in a more decentralized and informal way than the later Inca state.     

THE SLX MODEL

We provide a comprehensive overview of the strengths and weaknesses of different spatial econometric model specifications in terms of spillover effects. Based on this overview, we advocate taking the SLX model as point of departure in case a well‐founded theory indicating which model is most appropriate is lacking. In contrast to other spatial econometric models, the SLX model also allows for the spatial weights matrix W to be parameterized and the application of standard econometric techniques to test for endogenous explanatory variables. This starkly contrasts commonly used spatial econometric specification strategies and is a complement to the critique of spatial econometrics raised in a special theme issue of the Journal of Regional Science (Volume 52, Issue 2). To illustrate the pitfalls of the standard spatial econometrics approach and the benefits of our proposed alternative approach in an empirical setting, the Baltagi and Li (2004) cigarette demand model is estimated.     

Macusani obsidian from southern Peru: A characterization of its elemental composition with a demonstration of its ancient use

Transparent obsidian artifacts have been reported for the northern Lake Titicaca Basin. Based on instrumental neutron activation analysis (INAA) of these artifacts a distinct chemical group was identified. Yet, the location of the source of transparent obsidian in the southern Andes remained unreported in the archaeological literature. This paper reports on the chemical composition and geographic location of a source of transparent obsidian from the Macusani region of Peru. Through the use of INAA and portable X-ray fluorescence (PXRF) we demonstrate that Macusani obsidian or macusanite comprises (at least) two chemical groups. One of these groups was used for making artifacts during the Archaic Period. Artifacts made of this obsidian were found more than 120 km from the source and yet, one-third of the obsidian artifacts encountered at Macusani were from the non-local source of Chivay which is 215 km to the southwest.