https://research-explorer.ista.ac.at 2000-01-01T00:00+00:00 1 monthly https://research-explorer.ista.ac.at/record/454 Reiter, Johannes Hilbe, Christian Rand, David Chatterjee, Krishnendu Nowak, Martin 2018 Direct reciprocity is a mechanism for cooperation among humans. Many of our daily interactions are repeated. We interact repeatedly with our family, friends, colleagues, members of the local and even global community. In the theory of repeated games, it is a tacit assumption that the various games that a person plays simultaneously have no effect on each other. Here we introduce a general framework that allows us to analyze “crosstalk” between a player’s concurrent games. In the presence of crosstalk, the action a person experiences in one game can alter the person’s decision in another. We find that crosstalk impedes the maintenance of cooperation and requires stronger levels of forgiveness. The magnitude of the effect depends on the population structure. In more densely connected social groups, crosstalk has a stronger effect. A harsh retaliator, such as Tit-for-Tat, is unable to counteract crosstalk. The crosstalk framework provides a unified interpretation of direct and upstream reciprocity in the context of repeated games. https://research-explorer.ista.ac.at/record/454 https://research-explorer.ista.ac.at/download/454/4741 eng Nature Publishing Group info:eu-repo/semantics/altIdentifier/doi/10.1038/s41467-017-02721-8 info:eu-repo/semantics/altIdentifier/wos/000424318200001 info:eu-repo/grantAgreement/EC/FP7/279307 info:eu-repo/grantAgreement/FWF/P 23499-N23 info:eu-repo/grantAgreement/FWF/S11407 info:eu-repo/grantAgreement/EC/FP7/291734 info:eu-repo/semantics/openAccess Reiter J, Hilbe C, Rand D, Chatterjee K, Nowak M. Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness. <i>Nature Communications</i>. 2018;9(1). doi:<a href="https://doi.org/10.1038/s41467-017-02721-8">10.1038/s41467-017-02721-8</a> ddc:004 Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://research-explorer.ista.ac.at/record/7640 Kolesnikov, Alexander Kuznetsova, Alina Lampert, Christoph Ferrari, Vittorio 2019 We propose a new model for detecting visual relationships, such as "person riding motorcycle" or "bottle on table". This task is an important step towards comprehensive structured mage understanding, going beyond detecting individual objects. Our main novelty is a Box Attention mechanism that allows to model pairwise interactions between objects using standard object detection pipelines. The resulting model is conceptually clean, expressive and relies on well-justified training and prediction procedures. Moreover, unlike previously proposed approaches, our model does not introduce any additional complex components or hyperparameters on top of those already required by the underlying detection model. We conduct an experimental evaluation on two datasets, V-COCO and Open Images, demonstrating strong quantitative and qualitative results. https://research-explorer.ista.ac.at/record/7640 eng IEEE info:eu-repo/semantics/altIdentifier/doi/10.1109/ICCVW.2019.00217 info:eu-repo/semantics/altIdentifier/isbn/9781728150239 info:eu-repo/semantics/altIdentifier/wos/000554591601098 info:eu-repo/semantics/altIdentifier/arxiv/1807.02136 info:eu-repo/grantAgreement/EC/FP7/308036 info:eu-repo/semantics/openAccess Kolesnikov A, Kuznetsova A, Lampert C, Ferrari V. Detecting visual relationships using box attention. In: <i>Proceedings of the 2019 International Conference on Computer Vision Workshop</i>. IEEE; 2019. doi:<a href="https://doi.org/10.1109/ICCVW.2019.00217">10.1109/ICCVW.2019.00217</a> Detecting visual relationships using box attention info:eu-repo/semantics/conferenceObject doc-type:conferenceObject text http://purl.org/coar/resource_type/c_5794 https://research-explorer.ista.ac.at/record/9829 Baranov, Dmitry Šverko, Tara Moot, Taylor Keller, Helena R. Klein, Megan D. Vishnu, E. K. Balazs, Daniel Shulenberger, Katherine E. 2021 In 2020, many in-person scientific events were canceled due to the COVID-19 pandemic, creating a vacuum in networking and knowledge exchange between scientists. To fill this void in scientific communication, a group of early career nanocrystal enthusiasts launched the virtual seminar series, News in Nanocrystals, in the summer of 2020. By the end of the year, the series had attracted over 850 participants from 46 countries. In this Nano Focus, we describe the process of organizing the News in Nanocrystals seminar series; discuss its growth, emphasizing what the organizers have learned in terms of diversity and accessibility; and provide an outlook for the next steps and future opportunities. This summary and analysis of experiences and learned lessons are intended to inform the broader scientific community, especially those who are looking for avenues to continue fostering discussion and scientific engagement virtually, both during the pandemic and after. https://research-explorer.ista.ac.at/record/9829 eng American Chemical Society info:eu-repo/semantics/altIdentifier/doi/10.1021/acsnano.1c03276 info:eu-repo/semantics/altIdentifier/issn/1936-0851 info:eu-repo/semantics/altIdentifier/issn/1936-086X info:eu-repo/semantics/altIdentifier/wos/000679406500002 info:eu-repo/semantics/altIdentifier/pmid/34228432 info:eu-repo/semantics/openAccess News in Nanocrystals seminar: Self-assembly of early career researchers toward globally accessible nanoscience info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://research-explorer.ista.ac.at/record/9402 Schmid, Laura Chatterjee, Krishnendu Hilbe, Christian Nowak, Martin A. 2021 Direct and indirect reciprocity are key mechanisms for the evolution of cooperation. Direct reciprocity means that individuals use their own experience to decide whether to cooperate with another person. Indirect reciprocity means that they also consider the experiences of others. Although these two mechanisms are intertwined, they are typically studied in isolation. Here, we introduce a mathematical framework that allows us to explore both kinds of reciprocity simultaneously. We show that the well-known ‘generous tit-for-tat’ strategy of direct reciprocity has a natural analogue in indirect reciprocity, which we call ‘generous scoring’. Using an equilibrium analysis, we characterize under which conditions either of the two strategies can maintain cooperation. With simulations, we additionally explore which kind of reciprocity evolves when members of a population engage in social learning to adapt to their environment. Our results draw unexpected connections between direct and indirect reciprocity while highlighting important differences regarding their evolvability. https://research-explorer.ista.ac.at/record/9402 https://research-explorer.ista.ac.at/download/9402/14496 eng Springer Nature info:eu-repo/semantics/altIdentifier/doi/10.1038/s41562-021-01114-8 info:eu-repo/semantics/altIdentifier/issn/2397-3374 info:eu-repo/semantics/altIdentifier/wos/000650304000002 info:eu-repo/semantics/altIdentifier/pmid/33986519 info:eu-repo/grantAgreement/EC/H2020/863818 info:eu-repo/grantAgreement/EC/FP7/279307 info:eu-repo/semantics/openAccess Schmid L, Chatterjee K, Hilbe C, Nowak MA. A unified framework of direct and indirect reciprocity. <i>Nature Human Behaviour</i>. 2021;5(10):1292–1302. doi:<a href="https://doi.org/10.1038/s41562-021-01114-8">10.1038/s41562-021-01114-8</a> ddc:000 A unified framework of direct and indirect reciprocity info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://research-explorer.ista.ac.at/record/8434 Dimchev, Georgi A Amiri, Behnam Humphries, Ashley C. Schaks, Matthias Dimchev, Vanessa Stradal, Theresia E. B. Faix, Jan Krause, Matthias Way, Michael Falcke, Martin Rottner, Klemens 2020 Efficient migration on adhesive surfaces involves the protrusion of lamellipodial actin networks and their subsequent stabilization by nascent adhesions. The actin-binding protein lamellipodin (Lpd) is thought to play a critical role in lamellipodium protrusion, by delivering Ena/VASP proteins onto the growing plus ends of actin filaments and by interacting with the WAVE regulatory complex, an activator of the Arp2/3 complex, at the leading edge. Using B16-F1 melanoma cell lines, we demonstrate that genetic ablation of Lpd compromises protrusion efficiency and coincident cell migration without altering essential parameters of lamellipodia, including their maximal rate of forward advancement and actin polymerization. We also confirmed lamellipodia and migration phenotypes with CRISPR/Cas9-mediated Lpd knockout Rat2 fibroblasts, excluding cell type-specific effects. Moreover, computer-aided analysis of cell-edge morphodynamics on B16-F1 cell lamellipodia revealed that loss of Lpd correlates with reduced temporal protrusion maintenance as a prerequisite of nascent adhesion formation. We conclude that Lpd optimizes protrusion and nascent adhesion formation by counteracting frequent, chaotic retraction and membrane ruffling.This article has an associated First Person interview with the first author of the paper. https://research-explorer.ista.ac.at/record/8434 https://research-explorer.ista.ac.at/download/8434/8435 eng The Company of Biologists info:eu-repo/semantics/altIdentifier/doi/10.1242/jcs.239020 info:eu-repo/semantics/altIdentifier/issn/0021-9533 info:eu-repo/semantics/altIdentifier/issn/1477-9137 info:eu-repo/semantics/altIdentifier/wos/000534387800005 info:eu-repo/semantics/altIdentifier/pmid/ 32094266 info:eu-repo/grantAgreement/FWF/M02495 info:eu-repo/semantics/openAccess Dimchev GA, Amiri B, Humphries AC, et al. Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation. <i>Journal of Cell Science</i>. 2020;133(7). doi:<a href="https://doi.org/10.1242/jcs.239020">10.1242/jcs.239020</a> Cell Biology ddc:570 Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://research-explorer.ista.ac.at/record/17329 Alistarh, Dan-Adrian Chatterjee, Krishnendu Karrabi, Mehrdad Lazarsfeld, John M 2024 We initiate the study of game dynamics in the population protocol model: n agents each maintain a current local strategy and interact in pairs uniformly at random. Upon each interaction, the agents play a two-person game and receive a payoff from an underlying utility function, and they can subsequently update their strategies according to a fixed local algorithm. In this setting, we ask how the distribution over agent strategies evolves over a sequence of interactions, and we introduce a new distributional equilibrium concept to quantify the quality of such distributions. As an initial example, we study a class of repeated prisoner's dilemma games, and we consider a family of simple local update algorithms that yield non-trivial dynamics over the distribution of agent strategies. We show that these dynamics are related to a new class of high-dimensional Ehrenfest random walks, and we derive exact characterizations of their stationary distributions, bounds on their mixing times, and prove their convergence to approximate distributional equilibria. Our results highlight trade-offs between the local state space of each agent, and the convergence rate and approximation factor of the underlying dynamics. Our approach opens the door towards the further characterization of equilibrium computation for other classes of games and dynamics in the population setting. https://research-explorer.ista.ac.at/record/17329 https://research-explorer.ista.ac.at/download/17329/17335 eng Association for Computing Machinery info:eu-repo/semantics/altIdentifier/doi/10.1145/3662158.3662768 info:eu-repo/semantics/altIdentifier/isbn/9798400706684 info:eu-repo/grantAgreement/EC/H2020/863818 info:eu-repo/semantics/openAccess Alistarh D-A, Chatterjee K, Karrabi M, Lazarsfeld JM. Game dynamics and equilibrium computation in the population protocol model. In: <i>Proceedings of the 43rd Annual ACM Symposium on Principles of Distributed Computing</i>. Association for Computing Machinery; 2024:40-49. doi:<a href="https://doi.org/10.1145/3662158.3662768">10.1145/3662158.3662768</a> ddc:000 Game dynamics and equilibrium computation in the population protocol model info:eu-repo/semantics/conferenceObject doc-type:conferenceObject text http://purl.org/coar/resource_type/c_5794