Analyzing and Modeling Special Offer Campaigns in Location-based Social Networks

The proliferation of mobile handheld devices in combination with the technological advancements in mobile computing has led to a number of innovative services that make use of the location information available on such devices. Traditional yellow pages websites have now moved to mobile platforms, giving the opportunity to local businesses and potential, near-by, customers to connect. These platforms can offer an affordable advertisement channel to local businesses. One of the mechanisms offered by location-based social networks (LBSNs) allows businesses to provide special offers to their customers that connect through the platform. We collect a large time-series dataset from approximately 14 million venues on Foursquare and analyze the performance of such campaigns using randomization techniques and (non-parametric) hypothesis testing with statistical bootstrapping. Our main finding indicates that this type of promotions are not as effective as anecdote success stories might suggest. Finally, we design classifiers by extracting three different types of features that are able to provide an educated decision on whether a special offer campaign for a local business will succeed or not both in short and long term.Comment: in The 9th International AAAI Conference on Web and Social Media (ICWSM 2015

The Influence of Safety, Efficacy, and Medical Condition Severity on Natural v. Synthetic Drug Preference

Research indicates that there is a preference for natural v. synthetic products, but the influence of this preference on drug choice in the medical domain is largely unknown. We present 5 studies in which participants were asked to consider a hypothetical situation in which they had a medical issue requiring pharmacological therapy. Participants ( N = 1223) were asked to select a natural, plant-derived, or synthetic drug. In studies 1a and 1b, approximately 79% of participants selected the natural v. synthetic drug, even though the safety and efficacy of the drugs were identical. Furthermore, participants rated the natural drug as safer than the synthetic drug, and as that difference increased, the odds of choosing the natural over synthetic drug increased. In studies 2 and 3, approximately 20% of participants selected the natural drug even when they were informed that it was less safe (study 2) or less effective (study 3) than the synthetic drug. Finally, in study 4, approximately 65% of participants chose a natural over synthetic drug regardless of the severity of a specific medical condition (mild v. severe hypertension), and this choice was predicted by perceived safety and efficacy differences. Overall, these data indicate that there is a bias for natural over synthetic drugs. This bias could have implications for drug choice and usage

Practical Results on the Development of a Control Moment Gyro Based Attitude Control System for Agile Small Satellites

In this paper a new practical Attitude Control System is proposed, based on Control Moment Gyroscopes (CMG). These actuators can provide unique torque, angular momentum and slew rate capabilities to small satellites without any increase in power, mass or volume. This will help small satellites become more agile and maneuverable. Agility considerably increases the operational envelope and efficiency of spacecraft and substantially increases the return of earth and science mission data. The paper focuses on the practical work on developing the hardware for a low cost, miniature CMG for agile small satellites. Experimental results indicate the potential benefits of using CMGs. Specifically, a cluster of four Single Gimbal CMGs (SGCMG) is used to practically demonstrate full 3-axis control for a microsatellite class spacecraft. Additionally, results are presented on the development of a larger SGCMG proposed as an experimental payload for future enhanced microsatellite missions

Extrapolation of compactness on weighted Morrey spaces

In a previous work, "compact versions" of Rubio de Francia's weighted extrapolation theorem were proved, which allow one to extrapolate the compactness of a linear operator from just one space to the full range of weighted Lebesgue spaces where this operator is bounded. In this paper, we extend these results to the setting of weighted Morrey spaces. As applications, we easily obtain new results on the weighted compactness of commutators of Calderon-Zygmund singular integrals, rough singular integrals and Bochner-Riesz multipliers.Peer reviewe