Online Human-Bot Interactions: Detection, Estimation, and Characterization

Increasing evidence suggests that a growing amount of social media content is generated by autonomous entities known as social bots. In this work we present a framework to detect such entities on Twitter. We leverage more than a thousand features extracted from public data and meta-data about users: friends, tweet content and sentiment, network patterns, and activity time series. We benchmark the classification framework by using a publicly available dataset of Twitter bots. This training data is enriched by a manually annotated collection of active Twitter users that include both humans and bots of varying sophistication. Our models yield high accuracy and agreement with each other and can detect bots of different nature. Our estimates suggest that between 9% and 15% of active Twitter accounts are bots. Characterizing ties among accounts, we observe that simple bots tend to interact with bots that exhibit more human-like behaviors. Analysis of content flows reveals retweet and mention strategies adopted by bots to interact with different target groups. Using clustering analysis, we characterize several subclasses of accounts, including spammers, self promoters, and accounts that post content from connected applications.Comment: Accepted paper for ICWSM'17, 10 pages, 8 figures, 1 tabl

Arming the public with artificial intelligence to counter social bots

The increased relevance of social media in our daily life has been accompanied by efforts to manipulate online conversations and opinions. Deceptive social bots -- automated or semi-automated accounts designed to impersonate humans -- have been successfully exploited for these kinds of abuse. Researchers have responded by developing AI tools to arm the public in the fight against social bots. Here we review the literature on different types of bots, their impact, and detection methods. We use the case study of Botometer, a popular bot detection tool developed at Indiana University, to illustrate how people interact with AI countermeasures. A user experience survey suggests that bot detection has become an integral part of the social media experience for many users. However, barriers in interpreting the output of AI tools can lead to fundamental misunderstandings. The arms race between machine learning methods to develop sophisticated bots and effective countermeasures makes it necessary to update the training data and features of detection tools. We again use the Botometer case to illustrate both algorithmic and interpretability improvements of bot scores, designed to meet user expectations. We conclude by discussing how future AI developments may affect the fight between malicious bots and the public.Comment: Published in Human Behavior and Emerging Technologie

Trypanosoma cruzi strain TcIV infects raccoons from Illinois

BACKGROUND The northern limits of Trypanosoma cruzi across the territory of the United States remain unknown. The known vectors Triatoma sanguisuga and T. lecticularia find their northernmost limits in Illinois; yet, earlier screenings of those insects did not reveal the presence of the pathogen, which has not been reported in vectors or reservoir hosts in this state. OBJECTIVES Five species of medium-sized mammals were screened for the presence of T. cruzi. METHODS Genomic DNA was isolated from heart, spleen and skeletal muscle of bobcats (Lynx rufus, n = 60), raccoons (Procyon lotor, n = 37), nine-banded armadillos (Dasypus novemcinctus, n = 5), Virginia opossums (Didelphis virginiana, n = 3), and a red fox (Vulpes vulpes). Infections were detected targeting DNA from the kinetoplast DNA minicircle (kDNA) and satellite DNA (satDNA). The discrete typing unit (DTU) was determined by amplifying two gene regions: the Spliced Leader Intergenic Region (SL), via a multiplex polymerase chain reaction, and the 24Sα ribosomal DNA via a heminested reaction. Resulting sequences were used to calculate their genetic distance against reference DTUs. FINDINGS 18.9% of raccoons were positive for strain TcIV; the rest of mammals tested negative. MAIN CONCLUSIONS These results confirm for the first time the presence of T. cruzi in wildlife from Illinois, suggesting that a sylvatic life cycle is likely to occur in the region. The analyses of sequences of SL suggest that amplicons resulting from a commonly used multiplex reaction may yield non-homologous fragments

Reaction rate uncertainties and 26Al in AGB silicon carbide stardust

Stardust is a class of presolar grains each of which presents an ideally uncontaminated stellar sample. Mainstream silicon carbide (SiC) stardust formed in the extended envelopes of carbon-rich asymptotic giant branch (AGB) stars and incorporated the radioactive nucleus 26Al as a trace element. The aim of this paper is to analyse in detail the effect of nuclear uncertainties, in particular the large uncertainties of up to four orders of magnitude related to the 26Al_g+(p,gamma)27Si reaction rate, on the production of 26Al in AGB stars and compare model predictions to data obtained from laboratory analysis of SiC stardust grains. Stellar uncertainties are also briefly discussed. We use a detailed nucleosynthesis postprocessing code to calculate the 26Al/27Al ratios at the surface of AGB stars of different masses (M = 1.75, 3, and 5 M_sun) and metallicities (Z = 0.02, 0.012, and 0.008). For the lower limit and recommended value of the 26Al_g(p,gamma)27Si reaction rate, the predicted 26Al/27Al ratios replicate the upper values of the range of the 26Al/27Al ratios measured in SiC grains. For the upper limit of the 26Al_g(p,gamma)27Si reaction rate, instead, the predicted 26Al/27Al ratios are approximately 100 times lower and lie below the range observed in SiC grains. When considering models of different masses and metallicities, the spread of more than an order of magnitude in the 26Al/27Al ratios measured in stellar SiC grains is not reproduced. We propose two scenarios to explain the spread of the 26Al/27Al ratios observed in mainstream SiC, depending on the choice of the 26Al_g+p reaction rate. One involves different times of stardust formation, the other involves extra-mixing processes. Stronger conclusions will be possible after more information is available from future nuclear experiments on the 26Al_g+p reaction.Comment: 6 pages, 5 Postscript figures, accepted for publication in Astronomy and Astrophysic

Light and heavy element isotopic compositions of mainstream SiC grains.

Although a variety of types of pre-solar SiC grains have been classified by their C, N, and Si isotopic composition, the majority of such grains are so-called mainstream grains and are believed to have come from asymptotic giant branch stars [1]. We have previously reported the Mo isotopic compositions of presolar SiC grains whose C, N, and Si isotopic compositions were not known [2]. Since most presolar SiC grains fall in the mainstream group, we assumed that these grains were mainstream. The excellent match of the Mo isotopic data with expectations for nucleosynthesis in AGB stars was consistent with this identification. In order to better understand the distribution of isotopic compositions in presolar grains, we have begun to measure heavy element isotopic compositions of presolar SiC grains of known C, N and Si isotopic composition

Processing and Technology of Fruits and Vegetables, 1960

Tomato Variety Evaluation for Processing, 1961 / W. A. Gould, J. R. Geisman and Wade Schulte -- Evaluation of Sweet Corn Varieties for Processing / J. R. Geisman and W. A. Gould -- Small Fruit Variety Evaluation Studies for Freezing / D. R. Davis and H. L. Stammer -- Evaluation of Apples for Processing. I. Fruit Juice Blends / D. R. Davis and H. L. Stammer -- Evaluation of Apples for Processing. II. Canned Apple Slices / D. R. Davis and H. L. Stammer -- Evaluation of Apples for Processing. III. Frozen Apple Slices / D. R. Davis and H. L. Stammer -- Evaluation of Apples for Processing. IV. Frozen Fruit Pies / D. R. Davis and H. L. Stammer -- A Study of Several Varieties of Pumpkin and Squash for Canning and Freezing for Use in Pies / Robert H. Clayton, J. R. Geisman and W. A. Gould -- Factors Effecting the Consistency of Cream Style Corn / D. R. Davis and W. A. Gould -- The Objective Measurement of Tomato Juice Consistency / Robert Kluter and W. A. Gould -- A Method for the Detection of Drosophila Fly Eggs and Larvae in Tomato Products / J. R. Geisman and Winston D. Bash -- A Chemical Study of Flavor and Flavor Substances in Tomatoes / John Hal Johnson and W. A. Gould -- Tannin Content Effects Grape Juice Quality / D. R. Davis and H. L. Stammer -- pH Survey for Tomatoes in Ohio / W. D. Bash -- Flavor Studies with Sauerkraut / J. R. Geisman, S. S. Verma and W. A. Gould -- The Effect of Fill Weight on Drained Weight of Canned Tomatoes / Wade A. Schulte and W. A. Gould -- A New Method for the Manufacture of Apple Sirup / M. P. Baldauf, D. R. Davis and H. L. Stammer -- Studies on Color Retention in Canned R.T.P. Cherries / D. R. Davis and H. L. Stammer -- Clumping Studies in Canned Blueberries / D. R. Davis and H. L. Stammer -- Infra-red Peeling Studies. I. Apples. / L. Lafferty and W. A. Gould -- Infra-red Peeling Studies. II. Tomatoes. / W. A. Gould, Richard Leiss and Donall Streets -- The Effect of Water Holding Times and Temperatures on Quality of Tomatoes / Richard Leiss, Ernest Anderson and W. A. Gould -- Quality Attributes of Sweet Potatoes - Glass Packed / Donald A. Giesser and W. A. Gould -- A Study of Some of the Factors Effecting the Efficiency of Washing of Fruits and Vegetables. I. Tomatoes / W. A. Gould and J. R. Geisman -- A Study of Some of the Factors Effecting the Efficiency of Washing of Fruits and Vegetables. II. Sweet Corn / J. R. Geisman and W. A. Gould -- A Study of Alpha-keto Acids, Amino Acids, and Citric Acid in Eight Tomato Varieties, and Their Changes During Processing / Mokhtar M. Hamdy and W. A. Goul

Effects of fleas on nest success of Arctic barnacle geese:experimentally testing the mechanism

Parasites have detrimental effects on their hosts' fitness. Therefore, behavioural adaptations have evolved to avoid parasites or, when an individual is already in contact with a parasite, prevent or minimize infections. Such anti-parasite behaviours can be very effective, but can also be costly for the host. Specifically, ectoparasites can elicit strong host anti-parasite behaviours and interactions between fleas (Siphonaptera) and their hosts are one of the best studied. In altricial bird species, nest fleas can negatively affect both parent and offspring fitness components. However, knowledge on the effects of fleas on precocial bird species is scarce. Research on geese in the Canadian Arctic indicated that fleas have a negative impact on reproductive success. One possible hypothesis is that fleas may affect female incubation behaviour. Breeding females with many fleas in their nest may increase the frequency and/or duration of incubation breaks and could even totally desert their nest. The aim of our study was to 1) determine if a similar negative relationship existed between flea abundance and reproductive success in our study colony of Arctic breeding barnacle geese Branta leucopsis and 2) experimentally quantify if such effects could be explained by a negative effect of nest fleas on female behaviour. We compared host anti-parasite and incubation behaviour between experimentally flea-reduced and control nests using wildlife cameras and temperature loggers. We found that flea abundance was negatively associated with hatching success. We found little experimental support, however, for changes in behaviour of the breeding female as a possible mechanism to explain this effect