Wireless communication systems, such as wireless sensor networks and RFIDs, are increasingly adopted to transfer potential highly sensitive information. Since the wireless medium has a sharing nature, adversaries have a chance to eavesdrop confidential information from the communication systems. Adding artificial noises caused by friendly jammers emerges as a feasible defensive technique agains...

This paper aims to understand some of the mechanisms which dominate the phenomenon of knowledge diffusion in the process that is called 'interactive learning'. We examine how knowledge spreads in a network in which agents have 'face-toface' learning interactions. We define a social network structured as a graph consisting of agents (vertices) and connections (edges) and situated on a grid which...

Considering that in most developing countries there are still no comprehensive lists of addresses for a given geographical area, there has always been a problem in drawing samples from the community, ensuring randomisation in the selection of the subjects. This article discusses the geographical stratification by socio-economic status used to draw a multistage random sample from a community-bas...

Geographic disease surveillance methods identify regions that have higher disease rates than expected. These approaches are generally applied to incident or prevalent cases of disease. In some contexts, disease-related events rather than individuals are the appropriate units of analysis for geographic surveillance. We propose a compound Poisson approach that detects event clusters by testing in...

In mountain farms, challenges posed by the degree of land slope, altitude and harsh climate further compound multiple other possible constraints, particularly in relation to distance farm from farmstead. This study focused on how mountain-area dairy farmers factor geographical characteristics their fields into field-use decisions. To that end, we surveyed 72 who traditional Salers breed cattle ...

How does the geographic distance between potential acquiring and target firms affect acquisition strategy? Although popular discussions suggest that distance may be critically important to strategy, formal research on acquisition-based growth has paid little attention to spatial factors. This study examines how the distance between acquiring and target firms influences target selection, explori...

This vignette describes gdistance, an R package which provides functionality to calculate various distance measures and routes in heterogeneous geographic spaces represented as grids. Distances are fundamental to geospatial analysis (Tobler 1970). The most commonly used geographic distance measure is the great-circle distance, which represents the shortest line between two points, taking into a...