A number of organizations ranging from terrorist groups such as ISIS to politicians and nation states reportedly conduct explicit campaigns to influence opinion on social media, posing a risk to democratic processes. There is thus a growing need to identify and eliminate "influence bots" - realistic, automated identities that illicitly shape discussion on sites like Twitter and Facebook - before they get too influential. Spurred by such events, DARPA held a 4-week competition in February/March 2015 in which multiple teams supported by the DARPA Social Media in Strategic Communications program competed to identify a set of previously identified "influence bots" serving as ground truth on a specific topic within Twitter. Past work regarding influence bots often has difficulty supporting claims about accuracy, since there is limited ground truth (though some exceptions do exist [3,7]). However, with the exception of [3], no past work has looked specifically at identifying influence bots on a specific topic. This paper describes the DARPA Challenge and describes the methods used by the three top-ranked teams.Comment: IEEE Computer Magazine, in pres

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IntroductionKernza intermediate wheatgrass (IWG) is a perennial grain and forage crop. Intercropping IWG with legumes may increase the forage yields and nutritive value but may compromise Kernza grain yields. The interaction between IWG and legumes depends on planting season, row spacing, and legume species. Our aim was to evaluate the effects of those management practices on Kernza grain yield, summer and fall forage yield and nutritive value, weed biomass and, the profitability of the cropping system in Wisconsin, USA.MethodsIn the spring and fall of 2017, we planted eight cropping systems at 38 and 57 cm of row spacing: four IWG monocultures [control without N fertilization or weed removal (IWG), hand weed removal (hand weeded), IWG fertilized with urea at rates of 45 or 90 kg ha−1], and four IWG-legume intercrops (IWG with alfalfa, Berseem clover, Kura clover, or red clover).Results and discussionMost of the intercropping systems were similar to IWG monoculture in grain (ranging from 652 to 1,160 kg ha−1) and forage yield (ranging from 2,740 to 5,190 kg ha−1) and improved the forage quality. However, for spring planted IWG, intercropped with red clover or alfalfa, the grain and forage yields were lower than the IWG monoculture (~80 and 450 kg ha−1, respectively). The best performing intercrops in the first year were Kura clover in the spring planting (652 kg Kernza grain ha−1, 4,920 kg IWG forage ha−1 and 825 kg legume forage ha−1) and red clover in the fall planting (857 kg Kernza grain ha−1, 3,800 kg IWG forage ha−1, and 450 kg legume forage ha−1). In the second year, grain yield decreased 84% on average. Overall, the profitability of the IWG legume intercropping was high, encouraging the adoption of dual-purpose perennial crops.