Simple Scan Tests for Spatial Clustering on a Square Lattice

Many data sets collected for study areas consist of data values collected on a square lattice or for a set of pixels. Remotely sensed data provide perhaps the most common example. Frequently, we wish to know whether there are subregions of the study area that exhibit spatial clustering. In this article, we suggest how an approach for finding spatial clusters may be combined with the common practice of using 3‐by‐3 and 5‐by‐5 smoothing filters or kernels to construct two simple and easy‐to‐implement scan‐type tests. A simulation experiment shows that the power of these tests to find clusters compares favorably with an alternative test that is more complicated. The tests use simulated data, changes in a remotely sensed image for a study region in Texas, and data about wheat yields. Muchas bases de datos que se recopilan para una zona de estudio, consisten en valores recopilados en una retícula cuadrada o en un conjunto de pixeles. Los datos obtenidos por sensores remotos son quizá el ejemplo más común. Frecuentemente deseamos saber si existen subregiones de la zona de estudio que exhiban agrupamiento espacial. En este artículo, sugerimos cómo una aproximación para ubicar agrupamientos espaciales se puede combinar con la práctica común de usar filtros de suavizado (kernels) de 3‐por‐3 y 5‐por‐5 filtros, para construir dos test tipo scan, sencillos y fáciles de implementar. Un experimento de simulación demuestra que el poder de estas pruebas para ubicar agrupamientos, se compara favorablemente frente a otra prueba alternativa, que resulta más complicada. Las pruebas usan datos simulados, cambios en una imagen de satélite para un área de estudio en Texas, y con data acerca de los rendimientos de cultivos de trigo. 研究区收集的许多数据集是由基于方格网和像素采集的数据值组成的,遥感数据可能提供了最常见的范例。通常,我们希望了解研究区的子区域是否呈现空间集聚特征。本文提出了一种如何发现空间集聚的方法,可以与采用3*3和5*5平滑滤波或核函数的普通试验相结合,构造两个简单且易于操作的扫描试验。模拟实验结果显示,这些试验在寻找聚集特征的性能上优于更复杂的可替换性试验。文中所用的仿真模拟数据来源于德克萨斯州小麦产量的多时相遥感影像。     

Documentary Evidence and the Medieval Pottery Industry

EARLY in my study of the medieval pottery industry it became clear to me that, contrary to general belief, a reasonable body of documentary evidence bearing on the industry had survived, but that it would take some years to assemble and interpret. There is no corpus of documents from which to begin, for surviving evidence is not only scattered in a very wide variety of documents, but is also dispersed geographically in a number of local record repositories. It might seem sensible to delay publication until a larger proportion of this evidence has been studied, or at least to avoid analysis and generalization at this stage; but pottery and potters are of interest to archaeologists here and now, and there is nothing written on the industry save assemblages of unrelated facts, often strung together from widely different periods. An effort has, therefore, been made to assemble the material so far available into a coherent pattern. Since this is the first time that this has been done, the result will probably require drastic modification in a few years' time. If the interim report here presented stimulates others to prove it wrong, this paper will have achieved at least one of its purposes.¹     

Technological successions in the Middle Stone Age sequence of Diepkloof Rock Shelter,Western Cape,South Africa

The southern African MSA comprises a series of phases of unique technological innovations that fuel current models on the evolutionary processes of Anatomically Modern Humans. However, the nature and variability of these technological phases remain poorly documented. This study reports on the previously unpublished sequence of Diepkloof Rock Shelter (South Africa) and investigates the main technological changes therein, particularly emphasizing the emergence, succession and disappearance of the Still Bay (SB) and the Howiesons Poort (HP). We argue for technological change that occurred at different rates and under the influence of variable driving factors. Our model implies that the SB and the HP are not related to the influx of new populations but have regionally specific origins. Unlike the other techno-complexes, the HP at Diepkloof is subdivided into different phases (Early, Intermediate and Late) but only the upper phases resemble the so-called “classic” HP. Finally, the technological sequence of Diepkloof questions the homogeneous picture which has been so far assumed for the southern African MSA and places emphasis on the importance of exploring long regional sequences.     

An Overview of Maritime Archaeological Research of the Colonial Period in the French Antilles

This article provides a summary of the various maritime archaeology projects undertaken in the French Antilles (Guadeloupe and Martinique) since the 1980s that date to the 17th–19th century Colonial period. These projects are presented in the context of the principal maritime archaeological research questions. The results are analysed thematically touching on different aspects of archaeological research in littoral and underwater zones: coastal plantations, ports, and micro‐islets. Research carried out on wreck‐sites is presented with respect to their maritime use (commercial, naval, and cabotage). The nature and distribution of such sites provides information both on maritime routes and traffic, trade, conflicts, and environmental risks specific to the Antilles in the Colonial period.     

Large Kombewa flake production in north Oman

In this paper we present the results of surveys carried out in February 2016 along a palaeo‐drainage system near the village of Bisyah. We report first on the geological prospection, which was our main goal, and then present our discovery of the only known localities in north Oman of large Kombewa flake production (>10 cm up to 20 cm). Among the scatter of artefacts, we found cores and large Kombewa flakes with two opposed bulbs of percussion, a technology that had not been known in this region until now. In spite of the local features, the typo‐technological traits of the artefacts suggest that at least part of them resemble in some way the Acheulean techno‐complex, but there are still many questions remaining on the age of these artefacts.     

Contentious Realities: Politics of Creating an Image Archive with the Negev Bedouin in Southern Israel

This paper discusses the politics of creating an image archive amidst local Bedouin historicity in Southern Israel. To do so, it summarizes an archival initiative conducted during my fieldwork in Rāha?, Israel between 2011 and 2013, which broadly examined the presence and values of images in their society. I suggest that members compete over historical resources in attempts to augment limited cultural capital in the Negev, making efforts to collect and exhibit ‘shared’ histories contentious. This is particularly the case when local societies consider archival images rare artefacts and thus objects to be owned and protected. This paper concludes that control over archives and image objects, and the past, present, and future ideals to which they are used, is far from uniform amongst peripheral peoples in the Middle East. Visual evidence and the histories and presents it serves are indelibly localized within the prevailing status negotiations and current spatial divisions between Bedouin members in the Negev.