Efficient Beacon Deployment for Large-scale Positioning

Instant and precise localization of indoor mobile users is fundamental for supporting various sophisticated location-aware services. Using Bluetooth low-power beacons for mobile user positioning has been reported as an effective approach, where the beacon deployment positioning (BDP) problem has been defined. The paper introduces a novel approach for solving large-scale BDP problems, aiming to significantly reduce beacon consumption from existing solutions with much less computation complexity. Extensive simulations are conducted to verify the proposed algorithm, whose beacon consumption is about 1.14 to 1.67 times and 0.2 to 0.48 times compared to those of the Mixed Integer Linear Program (ILP) and a naive iBeacon solution respectively. We have also observed that the running time scales well with the growth of the number of Test Positions and attenuation factors.

Patterns of Cannabis Consumption, Social Networks, and Foraging

This study considered contextual factors (i.e., times, places, peers) associated with cannabis use. A total of 153 participants answered an anonymous online survey, completed the Cannabis Use Disorders Identification Test – Revised (CUDIT-R), and indicated their numbers of regular smoking partners, and times and places cannabis was normally purchased. Recent cannabis smokers had higher CUDIT-R scores and purchased cannabis from more places more often. Multiple regression considered subscales of the CUDIT-R. Greater cannabis consumption was associated with more smoking partners and purchases of cannabis at more times and places. Cannabis dependence was associated with cannabis purchases from more places and times and reports that there were more people prepared to do them favors. Harmful use was associated with more purchases at more locations. Patterns of cannabis foraging were compared with foraging behaviors previously observed for caffeine, nicotine, and alcohol. The data could inform the development and use of social media and location-aware services seeking to target risky substance use.