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3. Simplistic Collection and Labeling Practices Limit the Utility of Benchmark Datasets for Twitter Bot Detection

Author

Hays, Chris, Schutzman, Zachary, Raghavan, Manish, Walk, Erin, and Zimmer, Philipp

Subjects
Computer Science - Machine Learning, Computer Science - Social and Information Networks
Abstract

Accurate bot detection is necessary for the safety and integrity of online platforms. It is also crucial for research on the influence of bots in elections, the spread of misinformation, and financial market manipulation. Platforms deploy infrastructure to flag or remove automated accounts, but their tools and data are not publicly available. Thus, the public must rely on third-party bot detection. These tools employ machine learning and often achieve near perfect performance for classification on existing datasets, suggesting bot detection is accurate, reliable and fit for use in downstream applications. We provide evidence that this is not the case and show that high performance is attributable to limitations in dataset collection and labeling rather than sophistication of the tools. Specifically, we show that simple decision rules -- shallow decision trees trained on a small number of features -- achieve near-state-of-the-art performance on most available datasets and that bot detection datasets, even when combined together, do not generalize well to out-of-sample datasets. Our findings reveal that predictions are highly dependent on each dataset's collection and labeling procedures rather than fundamental differences between bots and humans. These results have important implications for both transparency in sampling and labeling procedures and potential biases in research using existing bot detection tools for pre-processing., Comment: 10 pages, 6 figures; updated citation, clarified language

Published
2023
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7. Unraveling the Contribution of Serotonergic Polymorphisms, Prefrontal Alpha Asymmetry, and Individual Alpha Peak Frequency to the Emotion-Related Impulsivity Endophenotype

Author

Javelle, Florian, Löw, Andreas, Bloch, Wilhelm, Hosang, Thomas, Jacobsen, Thomas, Johnson, Sheri L, Schenk, Alexander, and Zimmer, Philipp

Subjects
Clinical Research, Behavioral and Social Science, Genetics, Neurosciences, Brain Disorders, Aetiology, 2.1 Biological and endogenous factors, Endophenotypes, Genotype, Humans, Impulsive Behavior, Monoamine Oxidase, Serotonin Plasma Membrane Transport Proteins, Cortical activity, Serotonergic polymorphisms, emotion-related impulsivity, 5-HTTLPR, MAO-A, STin2, Emotion-related impulsivity, Individual alpha peak frequency, Alpha asymmetry, Psychology, Cognitive Sciences, Neurology & Neurosurgery
Abstract

The unique contribution of the serotonin transporter-linked polymorphic region (5-HTTLPR), intronic region 2 (STin2), and monoamine oxidase A (MAO-A) genes to individual differences in personality traits has been widely explored, and research has shown that certain forms of these polymorphisms relate to impulsivity and impulsivity-related disorders. Humans showing these traits are also described as having an asymmetrical prefrontal cortical activity when compared to others. In this explorative study, we examine the relationship between serotonergic neurotransmission polymorphisms, cortical activity features (prefrontal alpha asymmetry, individual alpha peak frequency [iAPF]), emotion-related and non-emotion-related impulsivity in humans. 5-HTTLPR, MAO-A, and STin2 polymorphisms were assessed in blood taken from 91 participants with high emotion-related impulsivity levels. Sixty-seven participants completed resting electroencephalography and a more comprehensive impulsivity index. In univariate analyses, iAPF correlated with both forms of emotion-related impulsivity. In multiple linear regression models, 5-HTTLPR polymorphism (model 1, adj. R2 = 15.2%) and iAPF were significant interacting predictors of emotion-related impulsivity, explaining a large share of the results' variance (model 2, adj. R2 = 21.2%). Carriers of the low transcriptional activity 5-HTTPLR and MAO-A phenotypes obtained higher emotion-related impulsivity scores than others did. No significant results were detected for non-emotion-related impulsivity or for a form of emotion-related impulsivity involving cognitive/motivational reactivity to emotion. Our findings support an endophenotypic approach to impulsivity, showing that tri-allelic 5-HTTLPR polymorphism, iAPF, and their interaction are relevant predictors of one form of emotion-related impulsivity.

Published
2022

18. Dietary intake of tryptophan tied emotion-related impulsivity in humans.

Author

Javelle, Florian, Li, Descartes, Zimmer, Philipp, and Johnson, Sheri L

Subjects
Pharmacology and Pharmaceutical Sciences, Biomedical and Clinical Sciences, Clinical Research, Neurosciences, Basic Behavioral and Social Science, Mental Health, Behavioral and Social Science, Eating, Emotions, Female, Humans, Impulsive Behavior, Male, Tryptophan, Vitamin B 6, serotonin, diet, impulsivity, emotion, Nutrition and Dietetics, Nutrition & Dietetics, Nutrition and dietetics
Abstract

Emotion-related impulsivity, defined as the tendency to say or do things that one later regret during periods of heightened emotion, has been tied to a broad range of psychopathologies. Previous work has suggested that emotion-related impulsivity is tied to an impaired function of the serotonergic system. Central serotonin synthesis relies on the intake of the essential amino acid, tryptophan and its ability to pass through the blood brain barrier. Objective: The aim of this study was to determine the association between emotion-related impulsivity and tryptophan intake. Methods: Undergraduate participants (N = 25, 16 women, 9 men) completed a self-rated measure of impulsivity (Three Factor Impulsivity Index, TFI) and daily logs of their food intake and exercise. These data were coded using the software NutriNote to evaluate intakes of tryptophan, large neutral amino acids, vitamins B6/B12, and exercise. Results: Correlational analyses indicated that higher tryptophan intake was associated with significantly lower scores on two out of three subscales of the TFI, Pervasive Influence of Feelings scores r = -.502, p

Published
2021

20. Einführung

Author

Zimmer, Philipp, Appell, Hans-Joachim, Zimmer, Philipp, and Appell, Hans-Joachim

Published
2021
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27. Cancer-related cognitive impairment in non-CNS cancer patients: Targeted review and future action plans in Europe

Author

Sleurs, Charlotte, Amidi, Ali, Wu, Lisa M., Kiesl, David, Zimmer, Philipp, Lange, Marie, Rogiers, Anne, Giffard, Benedicte, Binarelli, Giulia, Borghgraef, Cindy, Deprez, Sabine, Duivon, Mylène, De Ruiter, Michiel, Schagen, Sanne, Ahmed-Lecheheb, Djihane, Castel, Hélène, Buskbjerg, Cecilie R., Dos Santos, Mélanie, Joly, Florence, and Perrier, Joy

Published
2022
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31. Design of a multinational randomized controlled trial to assess the effects of structured and individualized exercise in patients with metastatic breast cancer on fatigue and quality of life: the EFFECT study

Author

Hiensch, Anouk E., Monninkhof, Evelyn M., Schmidt, Martina E., Zopf, Eva M., Bolam, Kate A., Aaronson, Neil K., Belloso, Jon, Bloch, Wilhelm, Clauss, Dorothea, Depenbusch, Johanna, Lachowicz, Milena, Pelaez, Mireia, Rundqvist, Helene, Senkus, Elzbieta, Stuiver, Martijn M., Trevaskis, Mark, Urruticoechea, Ander, Rosenberger, Friederike, van der Wall, Elsken, de Wit, G. Ardine, Zimmer, Philipp, Wengström, Yvonne, Steindorf, Karen, and May, Anne M.

Published
2022
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32. Acute exercise activates the AHR in peripheral blood mononuclear cells in an intensity-dependent manner.

Author

Joisten, Niklas, Walzik, David, Schenk, Alexander, Metcalfe, Alan J., Belen, Sergen, Schaaf, Kirill, Jacko, Daniel, Gehlert, Sebastian, Spiliopoulou, Polyxeni, Garzinsky, Ann-Marie, Thevis, Mario, Rappelt, Ludwig, Donath, Lars, Meuth, Sven G., Bloch, Wilhelm, and Zimmer, Philipp

Subjects
MONONUCLEAR leukocytes, ARYL hydrocarbon receptors, EXERCISE physiology, EXERCISE intensity, KYNURENINE
Abstract

The kynurenine pathway (KP) of tryptophan degradation generates several metabolites such as kynurenine (KYN) or kynurenic acid (KA) that serve as endogenous ligands of the aryl hydrocarbon receptor (AHR). Due to its distinct biological roles particularly modulating the immune system, the AHR is a current therapeutic target across different inflammation-related diseases. Here, we show an acute exercise-induced increase in AHR ligand availability on a systemic level and a kynurenine pathway activation in peripheral blood mononuclear cells (PBMCs). Concurrently, the AHR is activated in PBMCs following acute exercise. Exercise effects on both, kynurenic acid and AHR activation in PBMCs were greater in response to high-intensity interval exercise (HIIE) (50 min, six 3-min intervals at 90% V̇ o 2peak, and 3-min intervals at 50% V̇ o 2peak in between) compared with workload-matched moderate-intensity continuous exercise (MICE) (50 min). In conclusion, these data indicate a novel mechanistic link in how exercise modulates the immune system through the kynurenine pathway-AHR axis, potentially underlying exercise-induced benefits in various chronic diseases. NEW & NOTEWORTHY: The findings of this study show that acute endurance exercise activates a receptor that has been described to integrate metabolic signals into the immune system. We uncover a potential mechanistic link on how exercise modulates the immune system through the kynurenine pathway-AHR axis, potentially underlying exercise-induced benefits in various chronic diseases and of relevance for other cell types. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Acute exercise increases systemic kynurenine pathway metabolites and activates the AHR in human PBMCs

Author

Joisten, Niklas, primary, Walzik, David, additional, Schenk, Alexander, additional, Metcalfe, Alan J, additional, Belen, Sergen, additional, Schaaf, Kirill, additional, Jacko, Daniel, additional, Gehlert, Sebastian, additional, Spiliopoulou, Polyxeni, additional, Garzinsky, Ann-Marie, additional, Thevis, Mario, additional, Rappelt, Ludwig, additional, Donath, Lars, additional, Meuth, Sven G, additional, Bloch, Wilhelm, additional, and Zimmer, Philipp, additional

Published
2024
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46. High-intensity interval training and energy management education, compared with moderate continuous training and progressive muscle relaxation, for improving health-related quality of life in persons with multiple sclerosis: study protocol of a randomized controlled superiority trial with six months’ follow-up

Author

Patt, Nadine, Kool, Jan, Hersche, Ruth, Oberste, Max, Walzik, David, Joisten, Niklas, Caminada, Daniel, Ferrara, Francesca, Gonzenbach, Roman, Nigg, Claudio Renato, Kamm, Christian Philipp, Zimmer, Philipp, and Bansi, Jens

Published
2021
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