Semantics-Space-Time Cube. A Conceptual Framework for Systematic Analysis of Texts in Space and Time

We propose an approach to analyzing data in which texts are associated with spatial and temporal references with the aim to understand how the text semantics vary over space and time. To represent the semantics, we apply probabilistic topic modeling. After extracting a set of topics and representing the texts by vectors of topic weights, we aggregate the data into a data cube with the dimensions corresponding to the set of topics, the set of spatial locations (e.g., regions), and the time divided into suitable intervals according to the scale of the planned analysis. Each cube cell corresponds to a combination (topic, location, time interval) and contains aggregate measures characterizing the subset of the texts concerning this topic and having the spatial and temporal references within these location and interval. Based on this structure, we systematically describe the space of analysis tasks on exploring the interrelationships among the three heterogeneous information facets, semantics, space, and time. We introduce the operations of projecting and slicing the cube, which are used to decompose complex tasks into simpler subtasks. We then present a design of a visual analytics system intended to support these subtasks. To reduce the complexity of the user interface, we apply the principles of structural, visual, and operational uniformity while respecting the specific properties of each facet. The aggregated data are represented in three parallel views corresponding to the three facets and providing different complementary perspectives on the data. The views have similar look-and-feel to the extent allowed by the facet specifics. Uniform interactive operations applicable to any view support establishing links between the facets. The uniformity principle is also applied in supporting the projecting and slicing operations on the data cube. We evaluate the feasibility and utility of the approach by applying it in two analysis scenarios using geolocated social media data for studying people's reactions to social and natural events of different spatial and temporal scales

Cities on and off the map: A bibliometric assessment of urban globalisation research

Growing out of writings on Global (North) cities, urban globalisation research (UGR) has expanded its canon to engage with an increasing diversity of cities and locations. Yet, this broadening has been uneven and controversial in its theoretical horizons and empirical universe. Focusing on the latter, this paper combines bibliometric, demographic, economic and georeferenced data to assess how UGR maps onto internationally documented cities ( n : 1692). Our study analyses city-themed publications by city location, demographic size and home-country income (2000–2014). Drawing on social science publications indexed in English (Scopus database), our results provide grounds for cautious optimism: recent publications offer broader, though still uneven coverage. The moving spatial average of publication counts also implies that the topical centre of published research gravity is shifting away from Euro-America. Yet, UGR lags in its coverage of the urban geographical universe, failing to keep pace with the economic/demographic trends that are resulting in southward/eastward shifts in worldwide urbanisation. Furthermore, while smaller cities and those in lower-income countries are still sidelined, cities in upper-middle income countries exhibit the largest gaps between observed and expected publication values. In our conclusion, we contend that urban bibliometrics could be further mobilised to identify publication foci and lacunae. Applied to cities on and off the map and a broader universe of urban knowledges, bibliometrics could help move contentious debates forward, identifying newer paradigms that may be engaging the world of cities beyond the globalisation umbrella and charting out multiple and complex topical relations across variegated worlds of urbanism

New perspectives on Web search engine research

Purpose–The purpose of this chapter is to give an overview of the context of Web search and search engine-related research, as well as to introduce the reader to the sections and chapters of the book. Methodology/approach–We review literature dealing with various aspects of search engines, with special emphasis on emerging areas of Web searching, search engine evaluation going beyond traditional methods, and new perspectives on Webs earching. Findings–The approaches to studying Web search engines are manifold. Given the importance of Web search engines for knowledge acquisition, research from different perspectives needs to be integrated into a more cohesive perspective. Researchlimitations/implications–The chapter suggests a basis for research in the field and also introduces further research directions. Originality/valueofpaper–The chapter gives a concise overview of the topics dealt with in the book and also shows directions for researchers interested in Web search engines