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\n  \n 2024\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Multifractal organization of EEG signals in multiple sclerosis.\n \n \n \n \n\n\n \n Wątorek, M.; Tomczyk, W.; Gawłowska, M.; Golonka-Afek, N.; Żyrkowska, A.; Marona, M.; Wnuk, M.; Słowik, A.; Ochab, J. K.; Fafrowicz, M.; Marek, T.; and Oświęcimka, P.\n\n\n \n\n\n\n Biomedical Signal Processing and Control, 91: 105916. May 2024.\n \n\n\n\n
\n\n\n\n \n \n \"MultifractalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@article{watorek_multifractal_2024,\n\ttitle = {Multifractal organization of {EEG} signals in multiple sclerosis},\n\tvolume = {91},\n\tcopyright = {All rights reserved},\n\tissn = {1746-8094},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1746809423013496},\n\tdoi = {10/gtdj6f},\n\tabstract = {Quantifying the complex/multifractal organization of the brain signals is crucial to fully understanding the brain processes and structure. In this contribution, we performed the multifractal analysis of the electroencephalographic (EEG) data obtained from a controlled multiple sclerosis (MS) study, focusing on the correlation between the degree of multifractality, disease duration, and disability level. Our results reveal a significant correspondence between the complexity of the time series and multiple sclerosis development, quantified respectively by scaling exponents and the Expanded Disability Status Scale (EDSS). Namely, for some brain regions, a well-developed multifractality and little persistence of the time series were identified in patients with a high level of disability, whereas the control group and patients with low EDSS were characterized by persistence and monofractality of the signals. The analysis of the cross-correlations between EEG signals supported these results, with the most significant differences identified for patients with EDSS {\\textgreater}1 and the combined group of patients with EDSS ≤1 and controls. No association between the multifractality and disease duration was observed, indicating that the multifractal organization of the data is a hallmark of developing the disease. The observed complexity/multifractality of EEG signals is hypothetically a result of neuronal compensation – i.e., of optimizing neural processes in the presence of structural brain degeneration. The presented study is highly relevant due to the multifractal formalism used to quantify complexity and due to scarce resting-state EEG evidence for cortical reorganization associated with compensation.},\n\turldate = {2024-01-13},\n\tjournal = {Biomedical Signal Processing and Control},\n\tauthor = {Wątorek, Marcin and Tomczyk, Wojciech and Gawłowska, Magda and Golonka-Afek, Natalia and Żyrkowska, Aleksandra and Marona, Monika and Wnuk, Marcin and Słowik, Agnieszka and Ochab, Jeremi K. and Fafrowicz, Magdalena and Marek, Tadeusz and Oświęcimka, Paweł},\n\tmonth = may,\n\tyear = {2024},\n\tkeywords = {Complexity, EEG, Multifractal, Nonlinearity, Time series},\n\tpages = {105916},\n}\n\n
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\n Quantifying the complex/multifractal organization of the brain signals is crucial to fully understanding the brain processes and structure. In this contribution, we performed the multifractal analysis of the electroencephalographic (EEG) data obtained from a controlled multiple sclerosis (MS) study, focusing on the correlation between the degree of multifractality, disease duration, and disability level. Our results reveal a significant correspondence between the complexity of the time series and multiple sclerosis development, quantified respectively by scaling exponents and the Expanded Disability Status Scale (EDSS). Namely, for some brain regions, a well-developed multifractality and little persistence of the time series were identified in patients with a high level of disability, whereas the control group and patients with low EDSS were characterized by persistence and monofractality of the signals. The analysis of the cross-correlations between EEG signals supported these results, with the most significant differences identified for patients with EDSS \\textgreater1 and the combined group of patients with EDSS ≤1 and controls. No association between the multifractality and disease duration was observed, indicating that the multifractal organization of the data is a hallmark of developing the disease. The observed complexity/multifractality of EEG signals is hypothetically a result of neuronal compensation – i.e., of optimizing neural processes in the presence of structural brain degeneration. The presented study is highly relevant due to the multifractal formalism used to quantify complexity and due to scarce resting-state EEG evidence for cortical reorganization associated with compensation.\n
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\n  \n 2023\n \n \n (2)\n \n \n
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\n \n\n \n \n \n \n \n \n Investigating structural and functional aspects of the brain’s criticality in stroke.\n \n \n \n \n\n\n \n Janarek, J.; Drogosz, Z.; Grela, J.; Ochab, J. K.; and Oświęcimka, P.\n\n\n \n\n\n\n Scientific Reports, 13(1): 12341. July 2023.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
\n\n\n\n \n \n \"InvestigatingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@article{janarek_investigating_2023,\n\ttitle = {Investigating structural and functional aspects of the brain’s criticality in stroke},\n\tvolume = {13},\n\tcopyright = {2023 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-023-39467-x},\n\tdoi = {10.1038/s41598-023-39467-x},\n\tabstract = {This paper addresses the question of the brain’s critical dynamics after an injury such as a stroke. It is hypothesized that the healthy brain operates near a phase transition (critical point), which provides optimal conditions for information transmission and responses to inputs. If structural damage could cause the critical point to disappear and thus make self-organized criticality unachievable, it would offer the theoretical explanation for the post-stroke impairment of brain function. In our contribution, however, we demonstrate using network models of the brain, that the dynamics remain critical even after a stroke. In cases where the average size of the second-largest cluster of active nodes, which is one of the commonly used indicators of criticality, shows an anomalous behavior, it results from the loss of integrity of the network, quantifiable within graph theory, and not from genuine non-critical dynamics. We propose a new simple model of an artificial stroke that explains this anomaly. The proposed interpretation of the results is confirmed by an analysis of real connectomes acquired from post-stroke patients and a control group. The results presented refer to neurobiological data; however, the conclusions reached apply to a broad class of complex systems that admit a critical state.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2023-07-31},\n\tjournal = {Scientific Reports},\n\tauthor = {Janarek, Jakub and Drogosz, Zbigniew and Grela, Jacek and Ochab, Jeremi K. and Oświęcimka, Paweł},\n\tmonth = jul,\n\tyear = {2023},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {Complex networks, Dynamical systems, Network models, Phase transitions and critical phenomena, Stroke},\n\tpages = {12341},\n}\n\n
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\n This paper addresses the question of the brain’s critical dynamics after an injury such as a stroke. It is hypothesized that the healthy brain operates near a phase transition (critical point), which provides optimal conditions for information transmission and responses to inputs. If structural damage could cause the critical point to disappear and thus make self-organized criticality unachievable, it would offer the theoretical explanation for the post-stroke impairment of brain function. In our contribution, however, we demonstrate using network models of the brain, that the dynamics remain critical even after a stroke. In cases where the average size of the second-largest cluster of active nodes, which is one of the commonly used indicators of criticality, shows an anomalous behavior, it results from the loss of integrity of the network, quantifiable within graph theory, and not from genuine non-critical dynamics. We propose a new simple model of an artificial stroke that explains this anomaly. The proposed interpretation of the results is confirmed by an analysis of real connectomes acquired from post-stroke patients and a control group. The results presented refer to neurobiological data; however, the conclusions reached apply to a broad class of complex systems that admit a critical state.\n
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\n \n\n \n \n \n \n \n \n The importance of ocular artifact removal in single-trial ERP analysis: The case of the N250 in face learning.\n \n \n \n \n\n\n \n Kotowski, K.; Ochab, J.; Stapor, K.; and Sommer, W.\n\n\n \n\n\n\n Biomedical Signal Processing and Control, 79: 104115. January 2023.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@article{kotowski_importance_2023,\n\ttitle = {The importance of ocular artifact removal in single-trial {ERP} analysis: {The} case of the {N250} in face learning},\n\tvolume = {79},\n\tcopyright = {All rights reserved},\n\tissn = {1746-8094},\n\tshorttitle = {The importance of ocular artifact removal in single-trial {ERP} analysis},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1746809422005729},\n\tdoi = {10.1016/j.bspc.2022.104115},\n\tabstract = {Objective\nSingle-trial event-related potentials (ERPs) offer fine-grained information about the trajectories of the neurocognitive processes but are highly sensitive to any artifacts in the EEG signal. The primary aim of this study was to assess the impact of ocular artifact removal on the single-trial N250 ERP analysis of face learning in individual participants.\nMethods\nWe present a detailed description of our research-grade EEG hardware setup and a highly reproducible code (https://osf.io/aqhmn/) for generating time series of single-trial N250 ERP amplitudes and precise identification of a changepoint between face memory trace acquisition and maintenance. Ocular artifacts were removed using a new semi-automatic approach with only one hyperparameter based on the correlation between EEG components from independent component analysis (ICA) and the EOG signal.\nResults\nResults from the simulation study showed that our ocular artifact filtration decreased the average RMSE by half and achieved the highest increase of SNR among all the compared methods. It decreased standard deviations and improved the fit of the broken-line regression models for all participants by 25\\% ± 17\\% (min. 2\\%, max. 63\\%).\nConclusions and significance\nOcular artifact filtration had a substantial positive impact on the regression modeling of single-trial ERP amplitudes. Lack of ocular artifact removal can drastically distort the conclusions about the face learning process from single-trial N250 ERP experiments for individual participants. The changepoint locations changed for 13 out of 15 participants. This is the first published analysis of time series of single-trial N250 ERP amplitudes in face learning.},\n\tlanguage = {en},\n\turldate = {2022-08-22},\n\tjournal = {Biomedical Signal Processing and Control},\n\tauthor = {Kotowski, Krzysztof and Ochab, Jeremi and Stapor, Katarzyna and Sommer, Werner},\n\tmonth = jan,\n\tyear = {2023},\n\tkeywords = {Event-related potentials, Face learning, ICA, N250, Ocular artifacts, Single-trial},\n\tpages = {104115},\n}\n\n
\n
\n\n\n
\n Objective Single-trial event-related potentials (ERPs) offer fine-grained information about the trajectories of the neurocognitive processes but are highly sensitive to any artifacts in the EEG signal. The primary aim of this study was to assess the impact of ocular artifact removal on the single-trial N250 ERP analysis of face learning in individual participants. Methods We present a detailed description of our research-grade EEG hardware setup and a highly reproducible code (https://osf.io/aqhmn/) for generating time series of single-trial N250 ERP amplitudes and precise identification of a changepoint between face memory trace acquisition and maintenance. Ocular artifacts were removed using a new semi-automatic approach with only one hyperparameter based on the correlation between EEG components from independent component analysis (ICA) and the EOG signal. Results Results from the simulation study showed that our ocular artifact filtration decreased the average RMSE by half and achieved the highest increase of SNR among all the compared methods. It decreased standard deviations and improved the fit of the broken-line regression models for all participants by 25% ± 17% (min. 2%, max. 63%). Conclusions and significance Ocular artifact filtration had a substantial positive impact on the regression modeling of single-trial ERP amplitudes. Lack of ocular artifact removal can drastically distort the conclusions about the face learning process from single-trial N250 ERP experiments for individual participants. The changepoint locations changed for 13 out of 15 participants. This is the first published analysis of time series of single-trial N250 ERP amplitudes in face learning.\n
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\n  \n 2022\n \n \n (4)\n \n \n
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\n \n\n \n \n \n \n \n \n How Output Outweighs Input and Interlocutors Matter for Study-Abroad SLA: Computational Social Network Analysis of Learner Interactions.\n \n \n \n \n\n\n \n Paradowski, M. B.; Cierpich–Kozieł, A.; Chen, C.; and Ochab, J. K.\n\n\n \n\n\n\n The Modern Language Journal, 106(4): 694–725. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/modl.12811\n\n\n\n
\n\n\n\n \n \n \"HowPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
\n
@article{paradowski_how_2022,\n\ttitle = {How {Output} {Outweighs} {Input} and {Interlocutors} {Matter} for {Study}-{Abroad} {SLA}: {Computational} {Social} {Network} {Analysis} of {Learner} {Interactions}},\n\tvolume = {106},\n\tcopyright = {All rights reserved},\n\tissn = {1540-4781},\n\tshorttitle = {How {Output} {Outweighs} {Input} and {Interlocutors} {Matter} for {Study}-{Abroad} {SLA}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/modl.12811},\n\tdoi = {10.1111/modl.12811},\n\tabstract = {This data-driven study framed in the interactionist approach investigates the influence of social graph topology and peer interaction dynamics among foreign exchange students enrolled in an intensive German language course on second language acquisition (SLA) outcomes. Applying the algorithms and metrics of computational social network analysis (SNA), we find that (a) the best predictor of target language (TL) performance is reciprocal interactions in the language being acquired, (b) the proportion of output in the TL is a stronger predictor than input (Principle of Proportional Output), (c) there is a negative relationship between performance and interactions with same-first-language speakers, (d) a significantly underperforming English native-speaker dominated cluster is present, and (e) there are more intense interactions taking place between students of different proficiency levels. Unlike previous study abroad social network research concentrating on the microlevel of individual learners’ egocentric networks and presenting an emic view only, this study constitutes the first application of computational SNA to a complete learner network (sociogram). It provides new insights into the link between social relations and SLA with an etic perspective, showing how social network configuration and peer learner interaction are stronger predictors of TL performance than individual factors such as attitude or motivation, and offering a rigorous methodology for investigating the phenomenon.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2023-02-02},\n\tjournal = {The Modern Language Journal},\n\tauthor = {Paradowski, Michał B. and Cierpich–Kozieł, Agnieszka and Chen, Chih–Chun and Ochab, Jeremi K.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/modl.12811},\n\tkeywords = {community/cluster detection, computational social network analysis, interactionist approach, peer learner network, social graph, study abroad},\n\tpages = {694--725},\n}\n\n
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\n This data-driven study framed in the interactionist approach investigates the influence of social graph topology and peer interaction dynamics among foreign exchange students enrolled in an intensive German language course on second language acquisition (SLA) outcomes. Applying the algorithms and metrics of computational social network analysis (SNA), we find that (a) the best predictor of target language (TL) performance is reciprocal interactions in the language being acquired, (b) the proportion of output in the TL is a stronger predictor than input (Principle of Proportional Output), (c) there is a negative relationship between performance and interactions with same-first-language speakers, (d) a significantly underperforming English native-speaker dominated cluster is present, and (e) there are more intense interactions taking place between students of different proficiency levels. Unlike previous study abroad social network research concentrating on the microlevel of individual learners’ egocentric networks and presenting an emic view only, this study constitutes the first application of computational SNA to a complete learner network (sociogram). It provides new insights into the link between social relations and SLA with an etic perspective, showing how social network configuration and peer learner interaction are stronger predictors of TL performance than individual factors such as attitude or motivation, and offering a rigorous methodology for investigating the phenomenon.\n
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\n \n\n \n \n \n \n \n \n Detecting Ottokar II’s 1248–1249 uprising and its instigators in co-witnessing networks.\n \n \n \n \n\n\n \n Ochab, J. K.; Škvrňák, J.; and Škvrňák, M.\n\n\n \n\n\n\n Historical Methods: A Journal of Quantitative and Interdisciplinary History, 55(4): 189–208. October 2022.\n Publisher: Routledge _eprint: https://doi.org/10.1080/01615440.2022.2065397\n\n\n\n
\n\n\n\n \n \n \"DetectingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
\n
@article{ochab_detecting_2022,\n\ttitle = {Detecting {Ottokar} {II}’s 1248–1249 uprising and its instigators in co-witnessing networks},\n\tvolume = {55},\n\tcopyright = {All rights reserved},\n\tissn = {0161-5440},\n\turl = {https://doi.org/10.1080/01615440.2022.2065397},\n\tdoi = {10.1080/01615440.2022.2065397},\n\tabstract = {We provide a detailed case study showing how social network analysis allows scholars to detect an event affecting the entire historical network under consideration and identify the responsible actors. We study the middle 13th century in Czech lands, where a rigid political structure of noble families surrounding the monarchs led to the uprising of part of the nobility. Having collected data on approximately 2,400 noblemen from 576 charters, we attempted to uncover social network features pointing to the rebellion and expose the noblemen who joined it. We observed, among other such quantifiable features, assortativity increasing before and resetting to random after the rebellion, a drop in the number of stable connections and subgraph similarity between yearly networks and regional titles (burgraves) rising in centrality above royal court officials in that period. The presented methods can be directly translated to other person-document data of comparable or larger sizes, and we hope it can help detect or disambiguate the timing of similar major events and the roles of people involved in them.},\n\tnumber = {4},\n\turldate = {2022-12-27},\n\tjournal = {Historical Methods: A Journal of Quantitative and Interdisciplinary History},\n\tauthor = {Ochab, Jeremi K. and Škvrňák, Jan and Škvrňák, Michael},\n\tmonth = oct,\n\tyear = {2022},\n\tnote = {Publisher: Routledge\n\\_eprint: https://doi.org/10.1080/01615440.2022.2065397},\n\tkeywords = {Social network analysis, anomaly detection, medieval Bohemia, nobility, temporal networks},\n\tpages = {189--208},\n}\n\n
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\n We provide a detailed case study showing how social network analysis allows scholars to detect an event affecting the entire historical network under consideration and identify the responsible actors. We study the middle 13th century in Czech lands, where a rigid political structure of noble families surrounding the monarchs led to the uprising of part of the nobility. Having collected data on approximately 2,400 noblemen from 576 charters, we attempted to uncover social network features pointing to the rebellion and expose the noblemen who joined it. We observed, among other such quantifiable features, assortativity increasing before and resetting to random after the rebellion, a drop in the number of stable connections and subgraph similarity between yearly networks and regional titles (burgraves) rising in centrality above royal court officials in that period. The presented methods can be directly translated to other person-document data of comparable or larger sizes, and we hope it can help detect or disambiguate the timing of similar major events and the roles of people involved in them.\n
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\n \n\n \n \n \n \n \n \n Task-dependent fractal patterns of information processing in working memory.\n \n \n \n \n\n\n \n Ochab, J. K.; Wątorek, M.; Ceglarek, A.; Fafrowicz, M.; Lewandowska, K.; Marek, T.; Sikora-Wachowicz, B.; and Oświęcimka, P.\n\n\n \n\n\n\n Scientific Reports, 12(1): 17866. October 2022.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
\n\n\n\n \n \n \"Task-dependentPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@article{ochab_task-dependent_2022,\n\ttitle = {Task-dependent fractal patterns of information processing in working memory},\n\tvolume = {12},\n\tcopyright = {2022 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-022-21375-1},\n\tdoi = {10.1038/s41598-022-21375-1},\n\tabstract = {We applied detrended fluctuation analysis, power spectral density, and eigenanalysis of detrended cross-correlations to investigate fMRI data representing a diurnal variation of working memory in four visual tasks: two verbal and two nonverbal. We show that the degree of fractal scaling is regionally dependent on the engagement in cognitive tasks. A particularly apparent difference was found between memorisation in verbal and nonverbal tasks. Furthermore, the detrended cross-correlations between brain areas were predominantly indicative of differences between resting state and other tasks, between memorisation and retrieval, and between verbal and nonverbal tasks. The fractal and spectral analyses presented in our study are consistent with previous research related to visuospatial and verbal information processing, working memory (encoding and retrieval), and executive functions, but they were found to be more sensitive than Pearson correlations and showed the potential to obtain other subtler results. We conclude that regionally dependent cognitive task engagement can be distinguished based on the fractal characteristics of BOLD signals and their detrended cross-correlation structure.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-10-25},\n\tjournal = {Scientific Reports},\n\tauthor = {Ochab, Jeremi K. and Wątorek, Marcin and Ceglarek, Anna and Fafrowicz, Magdalena and Lewandowska, Koryna and Marek, Tadeusz and Sikora-Wachowicz, Barbara and Oświęcimka, Paweł},\n\tmonth = oct,\n\tyear = {2022},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {Cognitive neuroscience, Computational neuroscience, Neuroscience, Short-term memory, Statistical physics, Working memory, thermodynamics and nonlinear dynamics},\n\tpages = {17866},\n}\n\n
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\n We applied detrended fluctuation analysis, power spectral density, and eigenanalysis of detrended cross-correlations to investigate fMRI data representing a diurnal variation of working memory in four visual tasks: two verbal and two nonverbal. We show that the degree of fractal scaling is regionally dependent on the engagement in cognitive tasks. A particularly apparent difference was found between memorisation in verbal and nonverbal tasks. Furthermore, the detrended cross-correlations between brain areas were predominantly indicative of differences between resting state and other tasks, between memorisation and retrieval, and between verbal and nonverbal tasks. The fractal and spectral analyses presented in our study are consistent with previous research related to visuospatial and verbal information processing, working memory (encoding and retrieval), and executive functions, but they were found to be more sensitive than Pearson correlations and showed the potential to obtain other subtler results. We conclude that regionally dependent cognitive task engagement can be distinguished based on the fractal characteristics of BOLD signals and their detrended cross-correlation structure.\n
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\n \n\n \n \n \n \n \n \n Changepoint Detection in Noisy Data Using a Novel Residuals Permutation-Based Method (RESPERM): Benchmarking and Application to Single Trial ERPs.\n \n \n \n \n\n\n \n Sommer, W.; Stapor, K.; Kończak, G.; Kotowski, K.; Fabian, P.; Ochab, J.; Bereś, A.; and Ślusarczyk, G.\n\n\n \n\n\n\n Brain Sciences, 12(5): 525. May 2022.\n Number: 5 Publisher: Multidisciplinary Digital Publishing Institute\n\n\n\n
\n\n\n\n \n \n \"ChangepointPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@article{sommer_changepoint_2022,\n\ttitle = {Changepoint {Detection} in {Noisy} {Data} {Using} a {Novel} {Residuals} {Permutation}-{Based} {Method} ({RESPERM}): {Benchmarking} and {Application} to {Single} {Trial} {ERPs}},\n\tvolume = {12},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\tissn = {2076-3425},\n\tshorttitle = {Changepoint {Detection} in {Noisy} {Data} {Using} a {Novel} {Residuals} {Permutation}-{Based} {Method} ({RESPERM})},\n\turl = {https://www.mdpi.com/2076-3425/12/5/525},\n\tdoi = {10.3390/brainsci12050525},\n\tabstract = {An important problem in many fields dealing with noisy time series, such as psychophysiological single trial data during learning or monitoring treatment effects over time, is detecting a change in the model underlying a time series. Here, we present a new method for detecting a single changepoint in a linear time series regression model, termed residuals permutation-based method (RESPERM). The optimal changepoint in RESPERM maximizes Cohen’s effect size with the parameters estimated by the permutation of residuals in a linear model. RESPERM was compared with the SEGMENTED method, a well-established and recommended method for detecting changepoints, using extensive simulated data sets, varying the amount and distribution characteristics of noise and the location of the change point. In time series with medium to large amounts of noise, the variance of the detected changepoint was consistently smaller for RESPERM than SEGMENTED. Finally, both methods were applied to a sample dataset of single trial amplitudes of the N250 ERP component during face learning. In conclusion, RESPERM appears to be well suited for changepoint detection especially in noisy data, making it the method of choice in neuroscience, medicine and many other fields.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2022-04-21},\n\tjournal = {Brain Sciences},\n\tauthor = {Sommer, Werner and Stapor, Katarzyna and Kończak, Grzegorz and Kotowski, Krzysztof and Fabian, Piotr and Ochab, Jeremi and Bereś, Anna and Ślusarczyk, Grażyna},\n\tmonth = may,\n\tyear = {2022},\n\tnote = {Number: 5\nPublisher: Multidisciplinary Digital Publishing Institute},\n\tkeywords = {changepoint detection, event-related potentials, noisy time series, permutation method, segmented method},\n\tpages = {525},\n}\n\n
\n
\n\n\n
\n An important problem in many fields dealing with noisy time series, such as psychophysiological single trial data during learning or monitoring treatment effects over time, is detecting a change in the model underlying a time series. Here, we present a new method for detecting a single changepoint in a linear time series regression model, termed residuals permutation-based method (RESPERM). The optimal changepoint in RESPERM maximizes Cohen’s effect size with the parameters estimated by the permutation of residuals in a linear model. RESPERM was compared with the SEGMENTED method, a well-established and recommended method for detecting changepoints, using extensive simulated data sets, varying the amount and distribution characteristics of noise and the location of the change point. In time series with medium to large amounts of noise, the variance of the detected changepoint was consistently smaller for RESPERM than SEGMENTED. Finally, both methods were applied to a sample dataset of single trial amplitudes of the N250 ERP component during face learning. In conclusion, RESPERM appears to be well suited for changepoint detection especially in noisy data, making it the method of choice in neuroscience, medicine and many other fields.\n
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\n  \n 2021\n \n \n (7)\n \n \n
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\n \n\n \n \n \n \n \n \n Szerzőazonosítás Jacob és Wilhelm Grimm zajos, digitalizált levelezésében.\n \n \n \n \n\n\n \n Franzini, G.; Kestemont, M.; Rotari, G.; Jander, M.; Ochab, J. K.; Franzini, E.; Byszuk, J.; and Rybicki, J.\n\n\n \n\n\n\n Digitális Bölcsészet, (5). December 2021.\n \n\n\n\n
\n\n\n\n \n \n \"SzerzőazonosításPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{franzini_szerzoazonositas_2021,\n\ttitle = {Szerzőazonosítás {Jacob} és {Wilhelm} {Grimm} zajos, digitalizált levelezésében},\n\tcopyright = {All rights reserved},\n\tissn = {2630-9696},\n\turl = {http://ojs.elte.hu/digitalisbolcseszet/article/view/3144},\n\tdoi = {10.31400/dh-hun.2021.5.3144},\n\tabstract = {Az alábbi cikk egy multidiszciplináris projekt eredményeit mutatja be, amely a különböző digitalizációs stratégiák számítógépes szöveganalízisben való használhatóságát járja körül. Pontosabban Jacob és Wilhelm Grimm szerzőségének automatizált megkülönböztetésére tettünk kísérletet, melyet egy HTR (HandwrittenText Recognition – kézzel írott szöveg felismerése) és OCR (Optical Character Recognition – optikai karakterfelismerés) által feldolgozott levelezéskorpuszban hajtottunk végre, korrekció nélkül – felmérve, hogy az így keletkezett zaj milyen hatással van a fivérek különböző írásmódjának azonosítására. Összegezve,úgy tűnik, hogy az OCR megbízható helyettesítője lehet a manuális átírásnak, legalábbis a szerzőazonosítás kérdéskörét illetően. Eredményeink továbbá abba az irányba mutatnak, miszerint még a különböző digitalizációs eljárásokból származó tanító- és tesztkorpuszok (training and test set) is használhatók a szerzőazonosítás során. A HTR-t tekintve a kutatás azt demonstrálja, hogy ez az automatizált átírás ugyan az OCR-hez képest szignifikánsan növeli a szövegek félrecsoportosításának veszélyét, ám körülbelül 20\\% feletti tisztaság már önmagában elegendő ahhoz, hogy a véletlennél nagyobb esélye legyen a helyes binárismegfeleltetésnek.},\n\tnumber = {5},\n\turldate = {2022-01-18},\n\tjournal = {Digitális Bölcsészet},\n\tauthor = {Franzini, Greta and Kestemont, Mike and Rotari, Gabriela and Jander, Melina and Ochab, Jeremi K. and Franzini, Emily and Byszuk, Joanna and Rybicki, Jan},\n\tmonth = dec,\n\tyear = {2021},\n}\n\n
\n
\n\n\n
\n Az alábbi cikk egy multidiszciplináris projekt eredményeit mutatja be, amely a különböző digitalizációs stratégiák számítógépes szöveganalízisben való használhatóságát járja körül. Pontosabban Jacob és Wilhelm Grimm szerzőségének automatizált megkülönböztetésére tettünk kísérletet, melyet egy HTR (HandwrittenText Recognition – kézzel írott szöveg felismerése) és OCR (Optical Character Recognition – optikai karakterfelismerés) által feldolgozott levelezéskorpuszban hajtottunk végre, korrekció nélkül – felmérve, hogy az így keletkezett zaj milyen hatással van a fivérek különböző írásmódjának azonosítására. Összegezve,úgy tűnik, hogy az OCR megbízható helyettesítője lehet a manuális átírásnak, legalábbis a szerzőazonosítás kérdéskörét illetően. Eredményeink továbbá abba az irányba mutatnak, miszerint még a különböző digitalizációs eljárásokból származó tanító- és tesztkorpuszok (training and test set) is használhatók a szerzőazonosítás során. A HTR-t tekintve a kutatás azt demonstrálja, hogy ez az automatizált átírás ugyan az OCR-hez képest szignifikánsan növeli a szövegek félrecsoportosításának veszélyét, ám körülbelül 20% feletti tisztaság már önmagában elegendő ahhoz, hogy a véletlennél nagyobb esélye legyen a helyes binárismegfeleltetésnek.\n
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\n \n\n \n \n \n \n \n \n Revisiting Nonlinear Functional Brain Co-activations: Directed, Dynamic, and Delayed.\n \n \n \n \n\n\n \n Cifre, I.; Miller Flores, M. T.; Penalba, L.; Ochab, J. K.; and Chialvo, D. R.\n\n\n \n\n\n\n Frontiers in Neuroscience, 15: 1194. 2021.\n \n\n\n\n
\n\n\n\n \n \n \"RevisitingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{cifre_revisiting_2021,\n\ttitle = {Revisiting {Nonlinear} {Functional} {Brain} {Co}-activations: {Directed}, {Dynamic}, and {Delayed}},\n\tvolume = {15},\n\tcopyright = {All rights reserved},\n\tissn = {1662-453X},\n\tshorttitle = {Revisiting {Nonlinear} {Functional} {Brain} {Co}-activations},\n\turl = {https://www.frontiersin.org/article/10.3389/fnins.2021.700171},\n\tdoi = {10.3389/fnins.2021.700171},\n\tabstract = {The center stage of neuro-imaging is currently occupied by studies of functional correlations between brain regions. These correlations define the brain functional networks, which are the most frequently used framework to represent and interpret a variety of experimental findings. In the previous study, we first demonstrated that the relatively stronger blood oxygenated level dependent (BOLD) activations contain most of the information relevant to understand functional connectivity, and subsequent work confirmed that a large compression of the original signals can be obtained without significant loss of information. In this study, we revisit the correlation properties of these epochs to define a measure of nonlinear dynamic directed functional connectivity (nldFC) across regions of interest. We show that the proposed metric provides at once, without extensive numerical complications, directed information of the functional correlations, as well as a measure of temporal lags across regions, overall offering a different and complementary perspective in the analysis of brain co-activation patterns. In this study, we provide further details for the computations of these measures and for a proof of concept based on replicating existing results from an Autistic Syndrome database, and discuss the main features and advantages of the proposed strategy for the study of brain functional correlations.},\n\turldate = {2021-10-12},\n\tjournal = {Frontiers in Neuroscience},\n\tauthor = {Cifre, Ignacio and Miller Flores, Maria T. and Penalba, Lucia and Ochab, Jeremi K. and Chialvo, Dante R.},\n\tyear = {2021},\n\tpages = {1194},\n}\n\n
\n
\n\n\n
\n The center stage of neuro-imaging is currently occupied by studies of functional correlations between brain regions. These correlations define the brain functional networks, which are the most frequently used framework to represent and interpret a variety of experimental findings. In the previous study, we first demonstrated that the relatively stronger blood oxygenated level dependent (BOLD) activations contain most of the information relevant to understand functional connectivity, and subsequent work confirmed that a large compression of the original signals can be obtained without significant loss of information. In this study, we revisit the correlation properties of these epochs to define a measure of nonlinear dynamic directed functional connectivity (nldFC) across regions of interest. We show that the proposed metric provides at once, without extensive numerical complications, directed information of the functional correlations, as well as a measure of temporal lags across regions, overall offering a different and complementary perspective in the analysis of brain co-activation patterns. In this study, we provide further details for the computations of these measures and for a proof of concept based on replicating existing results from an Autistic Syndrome database, and discuss the main features and advantages of the proposed strategy for the study of brain functional correlations.\n
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\n \n\n \n \n \n \n \n \n Non-linear Functional Brain Co-activations in Short-Term Memory Distortion Tasks.\n \n \n \n \n\n\n \n Ceglarek, A.; Ochab, J. K.; Cifre, I.; Fafrowicz, M.; Sikora-Wachowicz, B.; Lewandowska, K.; Bohaterewicz, B.; Marek, T.; and Chialvo, D. R.\n\n\n \n\n\n\n Frontiers in Neuroscience, 15: 1611. 2021.\n \n\n\n\n
\n\n\n\n \n \n \"Non-linearPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ceglarek_non-linear_2021,\n\ttitle = {Non-linear {Functional} {Brain} {Co}-activations in {Short}-{Term} {Memory} {Distortion} {Tasks}},\n\tvolume = {15},\n\tcopyright = {Creative Commons Attribution 4.0 International Licence (CC-BY)},\n\tissn = {1662-453X},\n\turl = {https://www.frontiersin.org/article/10.3389/fnins.2021.778242},\n\tdoi = {10.3389/fnins.2021.778242},\n\tabstract = {Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 ± 3.56 y.o.) performed in MR scanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects’ responses were modeled with a general linear model, which includes as a predictor the non-linear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.},\n\turldate = {2021-12-03},\n\tjournal = {Frontiers in Neuroscience},\n\tauthor = {Ceglarek, Anna and Ochab, Jeremi K. and Cifre, Ignacio and Fafrowicz, Magdalena and Sikora-Wachowicz, Barbara and Lewandowska, Koryna and Bohaterewicz, Bartosz and Marek, Tadeusz and Chialvo, Dante R.},\n\tyear = {2021},\n\tpages = {1611},\n}\n\n
\n
\n\n\n
\n Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 ± 3.56 y.o.) performed in MR scanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects’ responses were modeled with a general linear model, which includes as a predictor the non-linear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.\n
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\n \n\n \n \n \n \n \n \n Untangling the brain web: from the early days of complex functional networks to the non-linear dynamical directed functional connectivity measures.\n \n \n \n \n\n\n \n Chialvo, D. R.; Cifre, I.; and Ochab, J. K.\n\n\n \n\n\n\n arXiv:2112.09806 [nlin, q-bio]. December 2021.\n arXiv: 2112.09806\n\n\n\n
\n\n\n\n \n \n \"UntanglingPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n\n\n\n
\n
@article{chialvo_untangling_2021,\n\ttitle = {Untangling the brain web: from the early days of complex functional networks to the non-linear dynamical directed functional connectivity measures},\n\tshorttitle = {Untangling the brain web},\n\turl = {http://arxiv.org/abs/2112.09806},\n\tabstract = {Already two decades passed since the first applications of graph theory to brain neuroimaging. Since that early description, the characterization of the brain as a very large interacting complex network has evolved in several directions. In this brief review we discuss our contributions to this topic and discuss some perspective for future work.},\n\turldate = {2022-01-10},\n\tjournal = {arXiv:2112.09806 [nlin, q-bio]},\n\tauthor = {Chialvo, Dante R. and Cifre, Ignacio and Ochab, Jeremi K.},\n\tmonth = dec,\n\tyear = {2021},\n\tnote = {arXiv: 2112.09806},\n\tkeywords = {Nonlinear Sciences - Adaptation and Self-Organizing Systems, Quantitative Biology - Neurons and Cognition, Quantitative Biology - Quantitative Methods, ⛔ No DOI found},\n}\n\n
\n
\n\n\n
\n Already two decades passed since the first applications of graph theory to brain neuroimaging. Since that early description, the characterization of the brain as a very large interacting complex network has evolved in several directions. In this brief review we discuss our contributions to this topic and discuss some perspective for future work.\n
\n\n\n
\n\n\n
\n \n\n \n \n \n \n \n \n Non-linear functional brain co-activations in short-term memory distortion tasks.\n \n \n \n \n\n\n \n Ceglarek, A.; Ochab, J. K.; Cifre, I.; Fafrowicz, M.; Sikora-Wachowicz, B.; Lewandowska, K.; Bohaterewicz, B.; Marek, T.; and Chialvo, D. R.\n\n\n \n\n\n\n bioRxiv,2021.09.12.459960. January 2021.\n \n\n\n\n
\n\n\n\n \n \n \"Non-linearPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ceglarek_non-linear_2021-1,\n\ttitle = {Non-linear functional brain co-activations in short-term memory distortion tasks},\n\tcopyright = {All rights reserved},\n\turl = {http://biorxiv.org/content/early/2021/09/15/2021.09.12.459960.abstract},\n\tdoi = {10.1101/2021.09.12.459960},\n\tabstract = {Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 y.o., SD: 3.56 y.o.) performed in MR scanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects' responses were modeled with a general linear model, which includes as a predictor the non-linear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.Competing Interest StatementThe authors have declared no competing interest.},\n\tjournal = {bioRxiv},\n\tauthor = {Ceglarek, Anna and Ochab, Jeremi K. and Cifre, Ignacio and Fafrowicz, Magdalena and Sikora-Wachowicz, Barbara and Lewandowska, Koryna and Bohaterewicz, Bartosz and Marek, Tadeusz and Chialvo, Dante R.},\n\tmonth = jan,\n\tyear = {2021},\n\tpages = {2021.09.12.459960},\n}\n\n
\n
\n\n\n
\n Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 y.o., SD: 3.56 y.o.) performed in MR scanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects' responses were modeled with a general linear model, which includes as a predictor the non-linear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.Competing Interest StatementThe authors have declared no competing interest.\n
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\n \n\n \n \n \n \n \n \n Observing changes in human functioning during induced sleep deficiency and recovery periods.\n \n \n \n \n\n\n \n Ochab, J. K.; Szwed, J.; Oleś, K.; Bereś, A.; Chialvo, D. R.; Domagalik, A.; Fąfrowicz, M.; Ogińska, H.; Gudowska-Nowak, E.; Marek, T.; and Nowak, M. A.\n\n\n \n\n\n\n PLOS ONE, 16(9): e0255771. September 2021.\n \n\n\n\n
\n\n\n\n \n \n \"ObservingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 4 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ochab_observing_2021,\n\ttitle = {Observing changes in human functioning during induced sleep deficiency and recovery periods},\n\tvolume = {16},\n\tcopyright = {All rights reserved},\n\tissn = {1932-6203},\n\turl = {https://dx.plos.org/10.1371/journal.pone.0255771},\n\tdoi = {10.1371/journal.pone.0255771},\n\tabstract = {Prolonged periods of sleep restriction seem to be common in the contemporary world. Sleep loss causes perturbations of circadian rhythmicity and degradation of waking alertness as reflected in attention, cognitive efficiency and memory. Understanding whether and how the human brain recovers from chronic sleep loss is important not only from a scientific but also from a public health perspective. In this work we report on behavioral, motor, and neurophysiological correlates of sleep loss in healthy adults in an unprecedented study conducted in natural conditions and comprising 21 consecutive days divided into periods of 4 days of regular life (a baseline), 10 days of chronic partial sleep restriction (30\\% reduction relative to individual sleep need) and 7 days of recovery. Throughout the whole experiment we continuously measured the spontaneous locomotor activity by means of actigraphy with 1-minute resolution. On a daily basis the subjects were undergoing EEG measurements (64-electrodes with 500 Hz sampling frequency): resting state with eyes open and closed (8 minutes long each) followed by Stroop task lasting 22 minutes. Altogether we analyzed actigraphy (distributions of rest and activity durations), behavioral measures (reaction times and accuracy from Stroop task) and EEG (amplitudes, latencies and scalp maps of event-related potentials from Stroop task and power spectra from resting states). We observed unanimous deterioration in all the measures during sleep restriction. Further results indicate that a week of recovery subsequent to prolonged periods of sleep restriction is insufficient to recover fully. Only one measure (mean reaction time in Stroop task) reverted to baseline values, while the others did not.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2021-09-02},\n\tjournal = {PLOS ONE},\n\tauthor = {Ochab, Jeremi K. and Szwed, Jerzy and Oleś, Katarzyna and Bereś, Anna and Chialvo, Dante R. and Domagalik, Aleksandra and Fąfrowicz, Magdalena and Ogińska, Halszka and Gudowska-Nowak, Ewa and Marek, Tadeusz and Nowak, Maciej A.},\n\teditor = {Scarpelli, Serena},\n\tmonth = sep,\n\tyear = {2021},\n\tpages = {e0255771},\n}\n\n
\n
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\n Prolonged periods of sleep restriction seem to be common in the contemporary world. Sleep loss causes perturbations of circadian rhythmicity and degradation of waking alertness as reflected in attention, cognitive efficiency and memory. Understanding whether and how the human brain recovers from chronic sleep loss is important not only from a scientific but also from a public health perspective. In this work we report on behavioral, motor, and neurophysiological correlates of sleep loss in healthy adults in an unprecedented study conducted in natural conditions and comprising 21 consecutive days divided into periods of 4 days of regular life (a baseline), 10 days of chronic partial sleep restriction (30% reduction relative to individual sleep need) and 7 days of recovery. Throughout the whole experiment we continuously measured the spontaneous locomotor activity by means of actigraphy with 1-minute resolution. On a daily basis the subjects were undergoing EEG measurements (64-electrodes with 500 Hz sampling frequency): resting state with eyes open and closed (8 minutes long each) followed by Stroop task lasting 22 minutes. Altogether we analyzed actigraphy (distributions of rest and activity durations), behavioral measures (reaction times and accuracy from Stroop task) and EEG (amplitudes, latencies and scalp maps of event-related potentials from Stroop task and power spectra from resting states). We observed unanimous deterioration in all the measures during sleep restriction. Further results indicate that a week of recovery subsequent to prolonged periods of sleep restriction is insufficient to recover fully. Only one measure (mean reaction time in Stroop task) reverted to baseline values, while the others did not.\n
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\n \n\n \n \n \n \n \n \n The N250 event-related potential as an index of face familiarity: a replication study.\n \n \n \n \n\n\n \n Sommer, W.; Stapor, K.; Kończak, G.; Kotowski, K.; Fabian, P.; Ochab, J.; Bereś, A.; and Ślusarczyk, G.\n\n\n \n\n\n\n Royal Society Open Science, 8(6): 202356. June 2021.\n Publisher: Royal Society\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{sommer_n250_2021,\n\ttitle = {The {N250} event-related potential as an index of face familiarity: a replication study},\n\tvolume = {8},\n\tcopyright = {All rights reserved},\n\tshorttitle = {The {N250} event-related potential as an index of face familiarity},\n\turl = {https://royalsocietypublishing.org/doi/10.1098/rsos.202356},\n\tdoi = {10.1098/rsos.202356},\n\tabstract = {The neural correlates of face individuation—the acquisition of memory representations for novel faces—have been studied only in coarse detail and disregarding individual differences between learners. In their seminal study, Tanaka et al. (Tanaka et al. 2006 J. Cogn. Neurosci.18, 1488–1497. (doi:10.1162/jocn.2006.18.9.1488)) required the identification of a particular novel face across 70 trials and found that the N250 component in the EEG event-related potentials became more negative from the first to the second half of the experiment, where it reached a similar amplitude as a well-known face. We were unable to directly replicate this finding in our study when we used the original split of trials. However, when we applied a different split of trials we observed very similar changes in N250 amplitude. We conclude that the N250 component is indeed sensitive to the build-up of a robust representation of a face in memory; the time course of this process appears to vary as a function of variables that may be determined in future research.},\n\tnumber = {6},\n\turldate = {2021-06-02},\n\tjournal = {Royal Society Open Science},\n\tauthor = {Sommer, Werner and Stapor, Katarzyna and Kończak, Grzegorz and Kotowski, Krzysztof and Fabian, Piotr and Ochab, Jeremi and Bereś, Anna and Ślusarczyk, Grażyna},\n\tmonth = jun,\n\tyear = {2021},\n\tnote = {Publisher: Royal Society},\n\tpages = {202356},\n}\n\n
\n
\n\n\n
\n The neural correlates of face individuation—the acquisition of memory representations for novel faces—have been studied only in coarse detail and disregarding individual differences between learners. In their seminal study, Tanaka et al. (Tanaka et al. 2006 J. Cogn. Neurosci.18, 1488–1497. (doi:10.1162/jocn.2006.18.9.1488)) required the identification of a particular novel face across 70 trials and found that the N250 component in the EEG event-related potentials became more negative from the first to the second half of the experiment, where it reached a similar amplitude as a well-known face. We were unable to directly replicate this finding in our study when we used the original split of trials. However, when we applied a different split of trials we observed very similar changes in N250 amplitude. We conclude that the N250 component is indeed sensitive to the build-up of a robust representation of a face in memory; the time course of this process appears to vary as a function of variables that may be determined in future research.\n
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\n  \n 2020\n \n \n (4)\n \n \n
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\n \n\n \n \n \n \n \n \n Single trial ERP amplitudes reveal the time course of acquiring representations of novel faces in individual participants.\n \n \n \n \n\n\n \n Sommer, W.; Stapor, K.; Konczak, G.; Kotowski, K.; Fabian, P.; Ochab, J.; Beres, A.; and Slusarczyk, G.\n\n\n \n\n\n\n arXiv:2012.00667 [q-bio, stat]. December 2020.\n arXiv: 2012.00667\n\n\n\n
\n\n\n\n \n \n \"SinglePaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n
@article{sommer_single_2020,\n\ttitle = {Single trial {ERP} amplitudes reveal the time course of acquiring representations of novel faces in individual participants},\n\tcopyright = {All rights reserved},\n\turl = {http://arxiv.org/abs/2012.00667},\n\tabstract = {The neural correlates of face individuation - the acquisition of memory representations for novel faces - have been studied only in coarse detail and disregarding individual differences between learners. In their seminal study, (Tanaka, Curran, Porterfield, \\& Collins, 2006) required the identification of a particular novel face across 70 trials and found that the N250 component in the ERP became more negative from the first to the second half of the experiment, where it reached a similar amplitude as a well-known face. We were unable to directly replicate this finding in our study when we used the original split of trials. However, when we applied a different split of trials we observed very similar changes in N250 amplitude. Then, we developed and applied a new two-step explorative-confirmative non-parametric method based on permutation testing to determine the time course of face individuation in individual participants based on single-trial N250 amplitudes. We show that the assumption of a steep initial increase of N250 amplitude across multiple presentations of the target face, followed by a plateau, yields plausible results in fitting linear trends for most participants. The transition point from initial acquisition to the plateau phase differed strongly between participants and tended to be earlier when performance in target face recognition was better. Hence, face individuation may be accounted for by a biphasic process of early, fast acquisition, followed by a slower, asymptotic consolidation or maintenance phase. The current approach might be fruitfully applied to further investigations into face individuation and their neural correlates},\n\turldate = {2021-03-12},\n\tjournal = {arXiv:2012.00667 [q-bio, stat]},\n\tauthor = {Sommer, W. and Stapor, K. and Konczak, G. and Kotowski, K. and Fabian, P. and Ochab, J. and Beres, A. and Slusarczyk, G.},\n\tmonth = dec,\n\tyear = {2020},\n\tnote = {arXiv: 2012.00667},\n\tkeywords = {Quantitative Biology - Neurons and Cognition, Statistics - Applications, ⛔ No DOI found},\n}\n\n
\n
\n\n\n
\n The neural correlates of face individuation - the acquisition of memory representations for novel faces - have been studied only in coarse detail and disregarding individual differences between learners. In their seminal study, (Tanaka, Curran, Porterfield, & Collins, 2006) required the identification of a particular novel face across 70 trials and found that the N250 component in the ERP became more negative from the first to the second half of the experiment, where it reached a similar amplitude as a well-known face. We were unable to directly replicate this finding in our study when we used the original split of trials. However, when we applied a different split of trials we observed very similar changes in N250 amplitude. Then, we developed and applied a new two-step explorative-confirmative non-parametric method based on permutation testing to determine the time course of face individuation in individual participants based on single-trial N250 amplitudes. We show that the assumption of a steep initial increase of N250 amplitude across multiple presentations of the target face, followed by a plateau, yields plausible results in fitting linear trends for most participants. The transition point from initial acquisition to the plateau phase differed strongly between participants and tended to be earlier when performance in target face recognition was better. Hence, face individuation may be accounted for by a biphasic process of early, fast acquisition, followed by a slower, asymptotic consolidation or maintenance phase. The current approach might be fruitfully applied to further investigations into face individuation and their neural correlates\n
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\n \n\n \n \n \n \n \n \n Deep Learning Methods in Electroencephalography.\n \n \n \n \n\n\n \n Kotowski, K.; Stapor, K.; and Ochab, J.\n\n\n \n\n\n\n In Tsihrintzis, G. A.; and Jain, L. C., editor(s), Machine Learning Paradigms: Advances in Deep Learning-based Technological Applications, of Learning and Analytics in Intelligent Systems, pages 191–212. Springer International Publishing, Cham, 2020.\n \n\n\n\n
\n\n\n\n \n \n \"DeepPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@incollection{kotowski_deep_2020,\n\taddress = {Cham},\n\tseries = {Learning and {Analytics} in {Intelligent} {Systems}},\n\ttitle = {Deep {Learning} {Methods} in {Electroencephalography}},\n\tcopyright = {All rights reserved},\n\tisbn = {978-3-030-49724-8},\n\turl = {https://doi.org/10.1007/978-3-030-49724-8_8},\n\tabstract = {The volume, variability and high level of noise in electroencephalographic (EEG) recordings of the electrical brain activity make them difficult to approach with standard machine learning techniques. Deep learning methods, especially artificial neural networks inspired by the structure of the brain itself are better suited for the domain because of their end-to-end approach. They have already shown outstanding performance in computer vision and they are increasingly popular in the EEG domain. In this chapter, the state-of-the-art architectures and approaches to classification, segmentation, and enhancement of EEG recordings are described in applications to brain-computer interfaces, medical diagnostics and emotion recognition. In the experimental part, the complete pipeline of deep learning for EEG is presented on the example of the detection of erroneous responses in the Eriksen flanker task with results showing advantages over a traditional machine learning approach. Additionally, the refined list of public EEG data sources suitable for deep learning and guidelines for future applications are given.},\n\tlanguage = {en},\n\turldate = {2020-08-25},\n\tbooktitle = {Machine {Learning} {Paradigms}: {Advances} in {Deep} {Learning}-based {Technological} {Applications}},\n\tpublisher = {Springer International Publishing},\n\tauthor = {Kotowski, Krzysztof and Stapor, Katarzyna and Ochab, Jeremi},\n\teditor = {Tsihrintzis, George A. and Jain, Lakhmi C.},\n\tyear = {2020},\n\tdoi = {10.1007/978-3-030-49724-8_8},\n\tpages = {191--212},\n}\n\n
\n
\n\n\n
\n The volume, variability and high level of noise in electroencephalographic (EEG) recordings of the electrical brain activity make them difficult to approach with standard machine learning techniques. Deep learning methods, especially artificial neural networks inspired by the structure of the brain itself are better suited for the domain because of their end-to-end approach. They have already shown outstanding performance in computer vision and they are increasingly popular in the EEG domain. In this chapter, the state-of-the-art architectures and approaches to classification, segmentation, and enhancement of EEG recordings are described in applications to brain-computer interfaces, medical diagnostics and emotion recognition. In the experimental part, the complete pipeline of deep learning for EEG is presented on the example of the detection of erroneous responses in the Eriksen flanker task with results showing advantages over a traditional machine learning approach. Additionally, the refined list of public EEG data sources suitable for deep learning and guidelines for future applications are given.\n
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\n \n\n \n \n \n \n \n \n From Synaptic Interactions to Collective Dynamics in Random Neuronal Networks Models: Critical Role of Eigenvectors and Transient Behavior.\n \n \n \n \n\n\n \n Gudowska-Nowak, E.; Nowak, M. A.; Chialvo, D. R.; Ochab, J. K.; and Tarnowski, W.\n\n\n \n\n\n\n Neural Computation, 32(2): 395–423. February 2020.\n \n\n\n\n
\n\n\n\n \n \n \"FromPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 4 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{gudowska-nowak_synaptic_2020,\n\ttitle = {From {Synaptic} {Interactions} to {Collective} {Dynamics} in {Random} {Neuronal} {Networks} {Models}: {Critical} {Role} of {Eigenvectors} and {Transient} {Behavior}},\n\tvolume = {32},\n\tcopyright = {All rights reserved},\n\tissn = {0899-7667, 1530-888X},\n\tshorttitle = {From {Synaptic} {Interactions} to {Collective} {Dynamics} in {Random} {Neuronal} {Networks} {Models}},\n\turl = {https://www.mitpressjournals.org/doi/abs/10.1162/neco_a_01253},\n\tdoi = {10.1162/neco_a_01253},\n\tabstract = {The study of neuronal interactions is at the center of several big collaborative neuroscience projects (including the Human Connectome Project, the Blue Brain Project, and the Brainome) that attempt to obtain a detailed map of the entire brain. Under certain constraints, mathematical theory can advance predictions of the expected neural dynamics based solely on the statistical properties of the synaptic interaction matrix. This work explores the application of free random variables to the study of large synaptic interaction matrices. Besides recovering in a straightforward way known results on eigenspectra in types of models of neural networks proposed by Rajan and Abbott ( 2006 ), we extend them to heavy-tailed distributions of interactions. More important, we analytically derive the behavior of eigenvector overlaps, which determine the stability of the spectra. We observe that on imposing the neuronal excitation/inhibition balance, despite the eigenvalues remaining unchanged, their stability dramatically decreases due to the strong nonorthogonality of associated eigenvectors. This leads us to the conclusion that understanding the temporal evolution of asymmetric neural networks requires considering the entangled dynamics of both eigenvectors and eigenvalues, which might bear consequences for learning and memory processes in these models. Considering the success of free random variables theory in a wide variety of disciplines, we hope that the results presented here foster the additional application of these ideas in the area of brain sciences.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-02-24},\n\tjournal = {Neural Computation},\n\tauthor = {Gudowska-Nowak, E. and Nowak, M. A. and Chialvo, D. R. and Ochab, J. K. and Tarnowski, W.},\n\tmonth = feb,\n\tyear = {2020},\n\tpages = {395--423},\n}\n\n
\n
\n\n\n
\n The study of neuronal interactions is at the center of several big collaborative neuroscience projects (including the Human Connectome Project, the Blue Brain Project, and the Brainome) that attempt to obtain a detailed map of the entire brain. Under certain constraints, mathematical theory can advance predictions of the expected neural dynamics based solely on the statistical properties of the synaptic interaction matrix. This work explores the application of free random variables to the study of large synaptic interaction matrices. Besides recovering in a straightforward way known results on eigenspectra in types of models of neural networks proposed by Rajan and Abbott ( 2006 ), we extend them to heavy-tailed distributions of interactions. More important, we analytically derive the behavior of eigenvector overlaps, which determine the stability of the spectra. We observe that on imposing the neuronal excitation/inhibition balance, despite the eigenvalues remaining unchanged, their stability dramatically decreases due to the strong nonorthogonality of associated eigenvectors. This leads us to the conclusion that understanding the temporal evolution of asymmetric neural networks requires considering the entangled dynamics of both eigenvectors and eigenvalues, which might bear consequences for learning and memory processes in these models. Considering the success of free random variables theory in a wide variety of disciplines, we hope that the results presented here foster the additional application of these ideas in the area of brain sciences.\n
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\n \n\n \n \n \n \n \n \n Evaluating the reliability of neurocognitive biomarkers of neurodegenerative diseases across countries: A machine learning approach.\n \n \n \n \n\n\n \n Bachli, M. B.; Sedeño, L.; Ochab, J. K.; Piguet, O.; Kumfor, F.; Reyes, P.; Torralva, T.; Roca, M.; Cardona, J. F.; Campo, C. G.; Herrera, E.; Slachevsky, A.; Matallana, D.; Manes, F.; García, A. M.; Ibáñez, A.; and Chialvo, D. R.\n\n\n \n\n\n\n NeuroImage, 208: 116456. March 2020.\n \n\n\n\n
\n\n\n\n \n \n \"EvaluatingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{bachli_evaluating_2020,\n\ttitle = {Evaluating the reliability of neurocognitive biomarkers of neurodegenerative diseases across countries: {A} machine learning approach},\n\tvolume = {208},\n\tcopyright = {All rights reserved},\n\tissn = {10538119},\n\tshorttitle = {Evaluating the reliability of neurocognitive biomarkers of neurodegenerative diseases across countries},\n\turl = {https://linkinghub.elsevier.com/retrieve/pii/S105381191931047X},\n\tdoi = {10.1016/j.neuroimage.2019.116456},\n\tlanguage = {en},\n\turldate = {2020-02-24},\n\tjournal = {NeuroImage},\n\tauthor = {Bachli, M. Belen and Sedeño, Lucas and Ochab, Jeremi K. and Piguet, Olivier and Kumfor, Fiona and Reyes, Pablo and Torralva, Teresa and Roca, María and Cardona, Juan Felipe and Campo, Cecilia Gonzalez and Herrera, Eduar and Slachevsky, Andrea and Matallana, Diana and Manes, Facundo and García, Adolfo M. and Ibáñez, Agustín and Chialvo, Dante R.},\n\tmonth = mar,\n\tyear = {2020},\n\tpages = {116456},\n}\n\n
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\n  \n 2019\n \n \n (4)\n \n \n
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\n \n\n \n \n \n \n \n \n Classifying attention deficit hyperactivity disorder in children with non-linearities in actigraphy.\n \n \n \n \n\n\n \n Ochab, J. K.; Gerc, K.; Fafrowicz, M.; Gudowska-Nowak, E.; Marek, T.; Nowak, M. A.; Oginska, H.; Oles, K.; Rams, M.; Szwed, J.; and Chialvo, D. R.\n\n\n \n\n\n\n arXiv:1902.03530 [nlin, physics:physics, q-bio]. February 2019.\n arXiv: 1902.03530\n\n\n\n
\n\n\n\n \n \n \"ClassifyingPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n\n\n\n
\n
@article{ochab_classifying_2019,\n\ttitle = {Classifying attention deficit hyperactivity disorder in children with non-linearities in actigraphy},\n\turl = {http://arxiv.org/abs/1902.03530},\n\tabstract = {Objective This study provides an objective measure based on actigraphy for Attention Deficit Hyperactivity Disorder (ADHD) diagnosis in children. We search for motor activity features that could allow further investigation into their association with other neurophysiological disordered traits. Method The study involved \\$n=29\\$ (48 eligible) male participants aged \\$9.89{\\textbackslash}pm0.92\\$ years (8 controls, and 7 in each group: ADHD combined subtype, ADHD hyperactive-impulsive subtype, and autism spectrum disorder, ASD) wearing a wristwatch actigraph continuously for a week (\\$9{\\textbackslash}\\%\\$ losses in daily records) in two acquisition modes. We analyzed 47 quantities: from sleep duration or movement intensity to theory-driven scaling exponents or non-linear prediction errors of both diurnal and nocturnal activity. We used them in supervised classification to obtain cross-validated diagnostic performance. Results We report the best performing measures, including a nearest neighbors 4-feature classifier providing \\$69.4{\\textbackslash}pm1.6{\\textbackslash}\\%\\$ accuracy, \\$78.0{\\textbackslash}pm2.2{\\textbackslash}\\%\\$ sensitivity and \\$60.8{\\textbackslash}pm2.6{\\textbackslash}\\%\\$ specificity in a binary ADHD vs control classification and \\$46.5{\\textbackslash}pm1.1{\\textbackslash}\\%\\$ accuracy (against \\$25{\\textbackslash}\\%\\$ baseline), \\$61.8{\\textbackslash}pm1.4{\\textbackslash}\\%\\$ sensitivity and \\$79.30 {\\textbackslash}pm0.43{\\textbackslash}\\%\\$ specificity in 4-class task (two ADHD subtypes, ASD, and control). The most informative feature is skewness of the shape of Zero Crossing Mode (ZCM) activity. Mean and standard deviation of nocturnal activity are among the least informative. Conclusion Actigraphy causes only minor discomfort to the subjects and is inexpensive. The range of existing mathematical and machine learning tools also allow it to be a useful add-on test for ADHD or differential diagnosis between ADHD subtypes. The study was limited to a small, male sample without the inattentive ADHD subtype.},\n\turldate = {2020-02-24},\n\tjournal = {arXiv:1902.03530 [nlin, physics:physics, q-bio]},\n\tauthor = {Ochab, Jeremi K. and Gerc, Krzysztof and Fafrowicz, Magdalena and Gudowska-Nowak, Ewa and Marek, Tadeusz and Nowak, Maciej A. and Oginska, Halszka and Oles, Katarzyna and Rams, Małgorzata and Szwed, Jerzy and Chialvo, Dante R.},\n\tmonth = feb,\n\tyear = {2019},\n\tnote = {arXiv: 1902.03530},\n\tkeywords = {Nonlinear Sciences - Adaptation and Self-Organizing Systems, Physics - Physics and Society, Quantitative Biology - Quantitative Methods, ⛔ No DOI found},\n}\n\n
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\n\n\n
\n Objective This study provides an objective measure based on actigraphy for Attention Deficit Hyperactivity Disorder (ADHD) diagnosis in children. We search for motor activity features that could allow further investigation into their association with other neurophysiological disordered traits. Method The study involved $n=29$ (48 eligible) male participants aged $9.89{\\}pm0.92$ years (8 controls, and 7 in each group: ADHD combined subtype, ADHD hyperactive-impulsive subtype, and autism spectrum disorder, ASD) wearing a wristwatch actigraph continuously for a week ($9{\\}%$ losses in daily records) in two acquisition modes. We analyzed 47 quantities: from sleep duration or movement intensity to theory-driven scaling exponents or non-linear prediction errors of both diurnal and nocturnal activity. We used them in supervised classification to obtain cross-validated diagnostic performance. Results We report the best performing measures, including a nearest neighbors 4-feature classifier providing $69.4{\\}pm1.6{\\}%$ accuracy, $78.0{\\}pm2.2{\\}%$ sensitivity and $60.8{\\}pm2.6{\\}%$ specificity in a binary ADHD vs control classification and $46.5{\\}pm1.1{\\}%$ accuracy (against $25{\\}%$ baseline), $61.8{\\}pm1.4{\\}%$ sensitivity and $79.30 {\\}pm0.43{\\}%$ specificity in 4-class task (two ADHD subtypes, ASD, and control). The most informative feature is skewness of the shape of Zero Crossing Mode (ZCM) activity. Mean and standard deviation of nocturnal activity are among the least informative. Conclusion Actigraphy causes only minor discomfort to the subjects and is inexpensive. The range of existing mathematical and machine learning tools also allow it to be a useful add-on test for ADHD or differential diagnosis between ADHD subtypes. The study was limited to a small, male sample without the inattentive ADHD subtype.\n
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\n \n\n \n \n \n \n \n \n On the pros and cons of using temporal derivatives to assess brain functional connectivity.\n \n \n \n \n\n\n \n Ochab, J. K.; Tarnowski, W.; Nowak, M. A.; and Chialvo, D. R.\n\n\n \n\n\n\n NeuroImage, 184: 577 – 585. 2019.\n \n\n\n\n
\n\n\n\n \n \n \"OnPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{ochab_pros_2019,\n\ttitle = {On the pros and cons of using temporal derivatives to assess brain functional connectivity},\n\tvolume = {184},\n\tcopyright = {All rights reserved},\n\tissn = {1053-8119},\n\turl = {http://www.sciencedirect.com/science/article/pii/S1053811918318676},\n\tdoi = {10.1016/j.neuroimage.2018.09.063},\n\tjournal = {NeuroImage},\n\tauthor = {Ochab, Jeremi K. and Tarnowski, Wojciech and Nowak, Maciej A. and Chialvo, Dante R.},\n\tyear = {2019},\n\tkeywords = {Functional connectivity, Resting state networks, fmri},\n\tpages = {577 -- 585},\n}\n\n
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\n \n\n \n \n \n \n \n \n Stylometry of literary papyri.\n \n \n \n \n\n\n \n Ochab, J. K.; and Essler, H.\n\n\n \n\n\n\n In Proceedings of the 3rd International Conference on Digital Access to Textual Cultural Heritage - DATeCH2019, pages 139–142, Brussels, Belgium, 2019. ACM Press\n \n\n\n\n
\n\n\n\n \n \n \"StylometryPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@inproceedings{ochab_stylometry_2019,\n\taddress = {Brussels, Belgium},\n\ttitle = {Stylometry of literary papyri},\n\tisbn = {9781450371940},\n\turl = {http://dl.acm.org/citation.cfm?doid=3322905.3322930},\n\tdoi = {10.1145/3322905.3322930},\n\tlanguage = {en},\n\turldate = {2020-02-24},\n\tbooktitle = {Proceedings of the 3rd {International} {Conference} on {Digital} {Access} to {Textual} {Cultural} {Heritage}  - {DATeCH2019}},\n\tpublisher = {ACM Press},\n\tauthor = {Ochab, Jeremi K. and Essler, Holger},\n\tyear = {2019},\n\tpages = {139--142},\n}\n\n
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\n \n\n \n \n \n \n \n \n The effects of a 10-day partial sleep deprivation and the following recovery on cognitive functioning – a behavioural and EEG study.\n \n \n \n \n\n\n \n Beres, A. M.; Domagalik, A.; Ochab, J. K.; Oleś, K.; Ogińska, H.; Fąfrowicz, M.; Marek, T.; Gudowska-Nowak, E.; Nowak, M. A.; Chialvo, D.; and Szwed, J.\n\n\n \n\n\n\n bioRxiv. 2019.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{beres_effects_2019,\n\ttitle = {The effects of a 10-day partial sleep deprivation and the following recovery on cognitive functioning – a behavioural and {EEG} study},\n\tcopyright = {All rights reserved},\n\turl = {https://www.biorxiv.org/content/early/2019/06/11/666396},\n\tdoi = {10.1101/666396},\n\tjournal = {bioRxiv},\n\tauthor = {Beres, Anna M. and Domagalik, Aleksandra and Ochab, Jeremi K. and Oleś, Katarzyna and Ogińska, Halszka and Fąfrowicz, Magdalena and Marek, Tadeusz and Gudowska-Nowak, Ewa and Nowak, Maciej A. and Chialvo, Dante and Szwed, Jerzy},\n\tyear = {2019},\n}\n
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\n  \n 2018\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Attributing Authorship in the Noisy Digitized Correspondence of Jacob and Wilhelm Grimm.\n \n \n \n \n\n\n \n Franzini, G.; Kestemont, M.; Rotari, G.; Jander, M.; Ochab, J. K.; Franzini, E.; Byszuk, J.; and Rybicki, J.\n\n\n \n\n\n\n Frontiers in Digital Humanities, 5: 4. 2018.\n \n\n\n\n
\n\n\n\n \n \n \"AttributingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{franzini_attributing_2018,\n\ttitle = {Attributing {Authorship} in the {Noisy} {Digitized} {Correspondence} of {Jacob} and {Wilhelm} {Grimm}},\n\tvolume = {5},\n\tcopyright = {All rights reserved},\n\tissn = {2297-2668},\n\turl = {https://www.frontiersin.org/article/10.3389/fdigh.2018.00004},\n\tdoi = {10.3389/fdigh.2018.00004},\n\tabstract = {This article presents the results of a multidisciplinary project aimed at better understanding the impact of different digitization strategies in computational text analysis. More specifically, it describes an effort to automatically discern the authorship of Jacob and Wilhelm Grimm in a body of uncorrected correspondence processed by HTR (Handwritten Text Recognition) and OCR (Optical Character Recognition), reporting on the effect this noise has on the analyses necessary to computationally identify the different writing style of the two brothers. In summary, our findings show that OCR digitization serves as a reliable proxy for the more painstaking process of manual digitization, at least when it comes to authorship attribution. Our results suggest that attribution is viable even when using training and test sets from different digitization pipelines. With regard to HTR, this research demonstrates that even though automated transcription significantly increases risk of text misclassification when compared to OCR, a cleanliness above ≈ 20\\% is already sufficient to achieve a higher-than-chance probability of correct binary attribution.},\n\tjournal = {Frontiers in Digital Humanities},\n\tauthor = {Franzini, Greta and Kestemont, Mike and Rotari, Gabriela and Jander, Melina and Ochab, Jeremi K. and Franzini, Emily and Byszuk, Joanna and Rybicki, Jan},\n\tyear = {2018},\n\tpages = {4},\n}\n\n
\n
\n\n\n
\n This article presents the results of a multidisciplinary project aimed at better understanding the impact of different digitization strategies in computational text analysis. More specifically, it describes an effort to automatically discern the authorship of Jacob and Wilhelm Grimm in a body of uncorrected correspondence processed by HTR (Handwritten Text Recognition) and OCR (Optical Character Recognition), reporting on the effect this noise has on the analyses necessary to computationally identify the different writing style of the two brothers. In summary, our findings show that OCR digitization serves as a reliable proxy for the more painstaking process of manual digitization, at least when it comes to authorship attribution. Our results suggest that attribution is viable even when using training and test sets from different digitization pipelines. With regard to HTR, this research demonstrates that even though automated transcription significantly increases risk of text misclassification when compared to OCR, a cleanliness above ≈ 20% is already sufficient to achieve a higher-than-chance probability of correct binary attribution.\n
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\n  \n 2017\n \n \n (2)\n \n \n
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\n \n\n \n \n \n \n \n \n Stylometric Networks and Fake Authorships.\n \n \n \n \n\n\n \n Ochab, J. K.\n\n\n \n\n\n\n Leonardo, 50(5): 502–502. 2017.\n \n\n\n\n
\n\n\n\n \n \n \"StylometricPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ochab_stylometric_2017,\n\ttitle = {Stylometric {Networks} and {Fake} {Authorships}},\n\tvolume = {50},\n\tcopyright = {All rights reserved},\n\turl = {https://doi.org/10.1162/LEON_a_01279},\n\tdoi = {10.1162/LEON_a_01279},\n\tabstract = {This paper addresses two problems: (a) whether and how tools developed to analyze network structures can be applied to the stylometric analysis of texts or text corpora and specifically to authorship attribution problems; and (b) whether it is possible to sample text fragments of an author A so as to imitate the style of an author B. The sample corpora in this study comprise 10–500 English novels from the 19th and 20th centuries.},\n\tnumber = {5},\n\tjournal = {Leonardo},\n\tauthor = {Ochab, Jeremi K.},\n\tyear = {2017},\n\tpages = {502--502},\n}\n\n
\n
\n\n\n
\n This paper addresses two problems: (a) whether and how tools developed to analyze network structures can be applied to the stylometric analysis of texts or text corpora and specifically to authorship attribution problems; and (b) whether it is possible to sample text fragments of an author A so as to imitate the style of an author B. The sample corpora in this study comprise 10–500 English novels from the 19th and 20th centuries.\n
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\n \n\n \n \n \n \n \n T\\lumacz rzeczy Randalla Munroe: zadania t\\lumacza książki objaśniającej świat obrazami.\n \n \n \n\n\n \n Ochab, J. K; and others\n\n\n \n\n\n\n Przek\\ladaniec, 2017(34): 88–107. 2017.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ochab_tlumacz_2017,\n\ttitle = {T{\\textbackslash}lumacz rzeczy {Randalla} {Munroe}: zadania t{\\textbackslash}lumacza książki objaśniającej świat obrazami},\n\tvolume = {2017},\n\tcopyright = {All rights reserved},\n\tdoi = {10.4467/16891864PC.17.005.8211},\n\tnumber = {34},\n\tjournal = {Przek{\\textbackslash}ladaniec},\n\tauthor = {Ochab, Jeremi K and {others}},\n\tyear = {2017},\n\tpages = {88--107},\n}\n\n
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\n  \n 2016\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Seeking a fingerprint: analysis of point processes in actigraphy recording.\n \n \n \n \n\n\n \n Gudowska-Nowak, E.; Ochab, J. K.; Oleś, K.; Beldzik, E.; Chialvo, D. R.; Aleksandra Domagalik; Fąfrowicz, M.; Marek, T.; Nowak, M. A.; Ogińska, H.; Szwed, J.; and Jacek Tyburczyk\n\n\n \n\n\n\n Journal of Statistical Mechanics: Theory and Experiment, 2016(5): 054034. 2016.\n \n\n\n\n
\n\n\n\n \n \n \"SeekingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{gudowska-nowak_seeking_2016,\n\ttitle = {Seeking a fingerprint: analysis of point processes in actigraphy recording},\n\tvolume = {2016},\n\tcopyright = {All rights reserved},\n\turl = {http://stacks.iop.org/1742-5468/2016/i=5/a=054034},\n\tdoi = {10.1088/1742-5468/2016/05/054034},\n\tabstract = {Motor activity of humans displays complex temporal fluctuations which can be characterised by scale-invariant statistics, thus demonstrating that structure and fluctuations of such kinetics remain similar over a broad range of time scales. Previous studies on humans regularly deprived of sleep or suffering from sleep disorders predicted a change in the invariant scale parameters with respect to those for healthy subjects. In this study we investigate the signal patterns from actigraphy recordings by means of characteristic measures of fractional point processes. We analyse spontaneous locomotor activity of healthy individuals recorded during a week of regular sleep and a week of chronic partial sleep deprivation. Behavioural symptoms of lack of sleep can be evaluated by analysing statistics of duration times during active and resting states, and alteration of behavioural organisation can be assessed by analysis of power laws detected in the event count distribution, distribution of waiting times between consecutive movements and detrended fluctuation analysis of recorded time series. We claim that among different measures characterising complexity of the actigraphy recordings and their variations implied by chronic sleep distress, the exponents characterising slopes of survival functions in resting states are the most effective biomarkers distinguishing between healthy and sleep-deprived groups.},\n\tnumber = {5},\n\tjournal = {Journal of Statistical Mechanics: Theory and Experiment},\n\tauthor = {Gudowska-Nowak, Ewa and Ochab, Jeremi K. and Oleś, Katarzyna and Beldzik, Ewa and Chialvo, Dante R. and {Aleksandra Domagalik} and Fąfrowicz, Magdalena and Marek, Tadeusz and Nowak, Maciej A. and Ogińska, Halszka and Szwed, Jerzy and {Jacek Tyburczyk}},\n\tyear = {2016},\n\tpages = {054034},\n}\n\n
\n
\n\n\n
\n Motor activity of humans displays complex temporal fluctuations which can be characterised by scale-invariant statistics, thus demonstrating that structure and fluctuations of such kinetics remain similar over a broad range of time scales. Previous studies on humans regularly deprived of sleep or suffering from sleep disorders predicted a change in the invariant scale parameters with respect to those for healthy subjects. In this study we investigate the signal patterns from actigraphy recordings by means of characteristic measures of fractional point processes. We analyse spontaneous locomotor activity of healthy individuals recorded during a week of regular sleep and a week of chronic partial sleep deprivation. Behavioural symptoms of lack of sleep can be evaluated by analysing statistics of duration times during active and resting states, and alteration of behavioural organisation can be assessed by analysis of power laws detected in the event count distribution, distribution of waiting times between consecutive movements and detrended fluctuation analysis of recorded time series. We claim that among different measures characterising complexity of the actigraphy recordings and their variations implied by chronic sleep distress, the exponents characterising slopes of survival functions in resting states are the most effective biomarkers distinguishing between healthy and sleep-deprived groups.\n
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\n  \n 2015\n \n \n (3)\n \n \n
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\n \n\n \n \n \n \n \n \n How we move is universal: Scaling in the average shape of human activity.\n \n \n \n \n\n\n \n Chialvo, D.; Torrado, A. G.; Gudowska-Nowak, E.; Ochab, J.; Montoya, P.; Nowak, M.; and Tagliazucchi, E.\n\n\n \n\n\n\n Papers in Physics, 7(0). 2015.\n \n\n\n\n
\n\n\n\n \n \n \"HowPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{chialvo_how_2015,\n\ttitle = {How we move is universal: {Scaling} in the average shape of human activity},\n\tvolume = {7},\n\tcopyright = {All rights reserved},\n\tissn = {1852-4249},\n\turl = {http://www.papersinphysics.org/papersinphysics/article/view/275},\n\tabstract = {Human motor activity is constrained by the rhythmicity of the 24 hours circadian cycle, including the usual 12-15 hours sleep-wake cycle. However, activity fluctuations also appear over a wide range of temporal scales, from days to a few seconds, resulting from the concatenation of a myriad of individual smaller motor events. Furthermore, individuals present different propensity to wakefulness and thus to motor activity throughout the circadian cycle. Are activity fluctuations across temporal scales intrinsically different, or is there a universal description encompassing them? Is this description also universal across individuals, considering the aforementioned variability? Here we establish the presence of universality in motor activity fluctuations based on the empirical study of a month of continuous wristwatch accelerometer recordings. We study the scaling of average fluctuations across temporal scales and determine a universal law characterized by critical exponents , and . Results are highly reminiscent of the universality described for the average shape of avalanches in systems exhibiting crackling noise. Beyond its theoretical relevance, the present results can be important for developing objective markers of healthy as well as pathological human motor behavior.Received: 18 October 2015, Accepted: 10 November 2015; Edited by: E. Mizraji; Reviewed by: J. Lin, Department of Physics, Washington College, Maryland, USA.; DOI: http://dx.doi.org/10.4279/PIP.070017Cite as: D R Chialvo, A M Gonzalez Torrado, E Gudowska-Nowak, J K Ochab, P Montoya, M A Nowak, E Tagliazucchi, Papers in Physics 7, 070017 (2015)This paper, by D R Chialvo, A M Gonzalez Torrado, E Gudowska-Nowak, J K Ochab, P Montoya, M A Nowak, E Tagliazucchi, is licensed under the Creative Commons Attribution License 3.0.},\n\tnumber = {0},\n\tjournal = {Papers in Physics},\n\tauthor = {Chialvo, Dante and Torrado, Ana Gonzalez and Gudowska-Nowak, Ewa and Ochab, Jeremi and Montoya, Pedro and Nowak, Maciej and Tagliazucchi, Enzo},\n\tyear = {2015},\n\tkeywords = {Circadian Cycle, Motor Activity, ⛔ No DOI found},\n}\n\n
\n
\n\n\n
\n Human motor activity is constrained by the rhythmicity of the 24 hours circadian cycle, including the usual 12-15 hours sleep-wake cycle. However, activity fluctuations also appear over a wide range of temporal scales, from days to a few seconds, resulting from the concatenation of a myriad of individual smaller motor events. Furthermore, individuals present different propensity to wakefulness and thus to motor activity throughout the circadian cycle. Are activity fluctuations across temporal scales intrinsically different, or is there a universal description encompassing them? Is this description also universal across individuals, considering the aforementioned variability? Here we establish the presence of universality in motor activity fluctuations based on the empirical study of a month of continuous wristwatch accelerometer recordings. We study the scaling of average fluctuations across temporal scales and determine a universal law characterized by critical exponents , and . Results are highly reminiscent of the universality described for the average shape of avalanches in systems exhibiting crackling noise. Beyond its theoretical relevance, the present results can be important for developing objective markers of healthy as well as pathological human motor behavior.Received: 18 October 2015, Accepted: 10 November 2015; Edited by: E. Mizraji; Reviewed by: J. Lin, Department of Physics, Washington College, Maryland, USA.; DOI: http://dx.doi.org/10.4279/PIP.070017Cite as: D R Chialvo, A M Gonzalez Torrado, E Gudowska-Nowak, J K Ochab, P Montoya, M A Nowak, E Tagliazucchi, Papers in Physics 7, 070017 (2015)This paper, by D R Chialvo, A M Gonzalez Torrado, E Gudowska-Nowak, J K Ochab, P Montoya, M A Nowak, E Tagliazucchi, is licensed under the Creative Commons Attribution License 3.0.\n
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\n \n\n \n \n \n \n \n \n A simple non-equilibrium, statistical-physics toy model of thin-film growth.\n \n \n \n \n\n\n \n Ochab, J. K.; Nagel, H.; Janke, W.; and Waclaw, B.\n\n\n \n\n\n\n Journal of Statistical Mechanics: Theory and Experiment, 2015(9): P09013. 2015.\n \n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
\n
@article{ochab_simple_2015,\n\ttitle = {A simple non-equilibrium, statistical-physics toy model of thin-film growth},\n\tvolume = {2015},\n\tcopyright = {All rights reserved},\n\turl = {http://stacks.iop.org/1742-5468/2015/i=9/a=P09013},\n\tdoi = {10.1088/1742-5468/2015/09/P09013},\n\tabstract = {We present a simple non-equilibrium model of mass condensation with Lennard–Jones interactions between particles and the substrate. We show that when some number of particles is deposited onto the surface and the system is left to equilibrate, particles condense into an island if the density of particles becomes higher than some critical density. We illustrate this with numerically obtained phase diagrams for three-dimensional systems. We also solve a two-dimensional counterpart of this model analytically and show that not only the phase diagram but also the shape of the cross-sections of three-dimensional condensates qualitatively matches the two-dimensional predictions. Lastly, we show that when particles are being deposited with a constant rate, the system has two phases: a single condensate for low deposition rates, and multiple condensates for fast deposition. The behaviour of our model is thus similar to that of thin film growth processes, and in particular to Stranski–Krastanov growth.},\n\tnumber = {9},\n\tjournal = {Journal of Statistical Mechanics: Theory and Experiment},\n\tauthor = {Ochab, Jeremi K. and Nagel, Hannes and Janke, Wolfhard and Waclaw, Bartlomiej},\n\tyear = {2015},\n\tpages = {P09013},\n}\n\n
\n
\n\n\n
\n We present a simple non-equilibrium model of mass condensation with Lennard–Jones interactions between particles and the substrate. We show that when some number of particles is deposited onto the surface and the system is left to equilibrate, particles condense into an island if the density of particles becomes higher than some critical density. We illustrate this with numerically obtained phase diagrams for three-dimensional systems. We also solve a two-dimensional counterpart of this model analytically and show that not only the phase diagram but also the shape of the cross-sections of three-dimensional condensates qualitatively matches the two-dimensional predictions. Lastly, we show that when particles are being deposited with a constant rate, the system has two phases: a single condensate for low deposition rates, and multiple condensates for fast deposition. The behaviour of our model is thus similar to that of thin film growth processes, and in particular to Stranski–Krastanov growth.\n
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\n \n\n \n \n \n \n \n Reinventing the Triangles: Rule of Thumb for Assessing Detectability.\n \n \n \n\n\n \n Ochab, J. K.\n\n\n \n\n\n\n In 2015 11th International Conference on Signal-Image Technology Internet-Based Systems (SITIS), pages 337–342, 2015. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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@inproceedings{ochab_reinventing_2015,\n\ttitle = {Reinventing the {Triangles}: {Rule} of {Thumb} for {Assessing} {Detectability}},\n\tcopyright = {All rights reserved},\n\tdoi = {10.1109/SITIS.2015.44},\n\tbooktitle = {2015 11th {International} {Conference} on {Signal}-{Image} {Technology} {Internet}-{Based} {Systems} ({SITIS})},\n\tauthor = {Ochab, J. K.},\n\tyear = {2015},\n\tkeywords = {Benchmark testing, Chlorine, Complex networks, Detection algorithms, Eigenvalues and eigenfunctions, Erbium, Standards, adjacency matrices, clustering coefficient, community detection, detectability limit, eigenspectra, global clustering coefficient, graph theory, matrix algebra, nonrandom module, pattern clustering, random matrix theory, triangle enumeration, undirected network, unweighted network},\n\tpages = {337--342},\n}\n\n
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\n  \n 2014\n \n \n (1)\n \n \n
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\n \n \n
\n \n\n \n \n \n \n \n \n Scale-Free Fluctuations in Behavioral Performance: Delineating Changes in Spontaneous Behavior of Humans with Induced Sleep Deficiency.\n \n \n \n \n\n\n \n Ochab, J. K.; Tyburczyk, J.; Beldzik, E.; Chialvo, D. R.; Domagalik, A.; Fafrowicz, M.; Gudowska-Nowak, E.; Marek, T.; Nowak, M. A.; Oginska, H.; and Szwed, J.\n\n\n \n\n\n\n PLoS ONE, 9(9): e107542. 2014.\n \n\n\n\n
\n\n\n\n \n \n \"Scale-FreePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 1 download\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ochab_scale-free_2014,\n\ttitle = {Scale-{Free} {Fluctuations} in {Behavioral} {Performance}: {Delineating} {Changes} in {Spontaneous} {Behavior} of {Humans} with {Induced} {Sleep} {Deficiency}},\n\tvolume = {9},\n\tcopyright = {All rights reserved},\n\turl = {http://dx.doi.org/10.1371%2Fjournal.pone.0107542},\n\tdoi = {10.1371/journal.pone.0107542},\n\tabstract = {{\\textless}p{\\textgreater}The timing and dynamics of many diverse behaviors of mammals, e.g., patterns of animal foraging or human communication in social networks exhibit complex self-similar properties reproducible over multiple time scales. In this paper, we analyze spontaneous locomotor activity of healthy individuals recorded in two different conditions: during a week of regular sleep and a week of chronic partial sleep deprivation. After separating activity from rest with a pre-defined activity threshold, we have detected distinct statistical features of duration times of these two states. The cumulative distributions of activity periods follow a stretched exponential shape, and remain similar for both control and sleep deprived individuals. In contrast, rest periods, which follow power-law statistics over two orders of magnitude, have significantly distinct distributions for these two groups and the difference emerges already after the first night of shortened sleep. We have found steeper distributions for sleep deprived individuals, which indicates fewer long rest periods and more turbulent behavior. This separation of power-law exponents is the main result of our investigations, and might constitute an objective measure demonstrating the severity of sleep deprivation and the effects of sleep disorders.{\\textless}/p{\\textgreater}},\n\tnumber = {9},\n\tjournal = {PLoS ONE},\n\tauthor = {Ochab, Jeremi K. and Tyburczyk, Jacek and Beldzik, Ewa and Chialvo, Dante R. and Domagalik, Aleksandra and Fafrowicz, Magdalena and Gudowska-Nowak, Ewa and Marek, Tadeusz and Nowak, Maciej A. and Oginska, Halszka and Szwed, Jerzy},\n\tyear = {2014},\n\tpages = {e107542},\n}\n\n
\n
\n\n\n
\n \\textlessp\\textgreaterThe timing and dynamics of many diverse behaviors of mammals, e.g., patterns of animal foraging or human communication in social networks exhibit complex self-similar properties reproducible over multiple time scales. In this paper, we analyze spontaneous locomotor activity of healthy individuals recorded in two different conditions: during a week of regular sleep and a week of chronic partial sleep deprivation. After separating activity from rest with a pre-defined activity threshold, we have detected distinct statistical features of duration times of these two states. The cumulative distributions of activity periods follow a stretched exponential shape, and remain similar for both control and sleep deprived individuals. In contrast, rest periods, which follow power-law statistics over two orders of magnitude, have significantly distinct distributions for these two groups and the difference emerges already after the first night of shortened sleep. We have found steeper distributions for sleep deprived individuals, which indicates fewer long rest periods and more turbulent behavior. This separation of power-law exponents is the main result of our investigations, and might constitute an objective measure demonstrating the severity of sleep deprivation and the effects of sleep disorders.\\textless/p\\textgreater\n
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\n  \n 2013\n \n \n (2)\n \n \n
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\n \n\n \n \n \n \n \n \n Static and dynamic properties of selected stochastic processes on complex networks.\n \n \n \n \n\n\n \n Ochab, J. K.\n\n\n \n\n\n\n Ph.D. Thesis, Jagiellonian University, July 2013.\n \n\n\n\n
\n\n\n\n \n \n \"StaticPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@phdthesis{ochab_static_2013,\n\ttype = {Doctoral thesis},\n\ttitle = {Static and dynamic properties of selected stochastic processes on complex networks},\n\tcopyright = {Creative Commons Attribution-ShareAlike 4.0 International Licence (CC-BY-SA)},\n\turl = {http://doi.org/10.31237/osf.io/4kbgj},\n\tabstract = {This thesis is concerned with the properties of a number of selected processes taking place on complex networks  and the way they are affected by structure and evolution of the networks.  What is meant here by 'complex networks' is the graph-theoretical representations and models of various empirical networks (e.g., the Internet network)  which contain both random and deterministic structures,  and are characterised among others by the small-world phenomenon, power-law vertex degree distributions, or modular and hierarchical structure.  The mathematical models of the processes taking place on these networks include percolation and random walks we utilise.\nThe results presented in the thesis are based on five thematically coherent papers.  The subject of the first paper is calculating thresholds for epidemic outbreaks on dynamic networks, where the disease spread is modelled by percolation.  In the paper, known analytical solutions for the epidemic thresholds were extended to a class of dynamically evolving networks;  additionally, the effects of finite size of the network on the magnitude of the epidemic were studied numerically.  The subject of the second and third paper is the static and dynamic properties of two diametrically opposed random walks on model highly symmetric deterministic graphs.  Specifically, we analytically and numerically find the stationary states and relaxation times of the ordinary, diffusive random walk and the maximal-entropy random walk.  The results provide insight into localisation of random walks or their trapping in isolated regions of networks.  Finally, in the fourth and fifth paper, we examine the utility of random walks in detecting topological features of complex networks.  In particular, we study properties of the centrality measures (roughly speaking, the ranking of vertices)  based on random walks,  as well as we conduct a systematic comparative study of random-walk based methods of detecting modular structure of networks.\nThese studies thus aimed at specific problems in modelling and analysis of complex networks,  including theoretical examination of the ways the behaviour of random processes intertwines with the structure of complex networks.},\n\tlanguage = {en-us},\n\turldate = {2021-12-15},\n\tschool = {Jagiellonian University},\n\tauthor = {Ochab, Jeremi K.},\n\tmonth = jul,\n\tyear = {2013},\n}\n\n
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\n This thesis is concerned with the properties of a number of selected processes taking place on complex networks and the way they are affected by structure and evolution of the networks. What is meant here by 'complex networks' is the graph-theoretical representations and models of various empirical networks (e.g., the Internet network) which contain both random and deterministic structures, and are characterised among others by the small-world phenomenon, power-law vertex degree distributions, or modular and hierarchical structure. The mathematical models of the processes taking place on these networks include percolation and random walks we utilise. The results presented in the thesis are based on five thematically coherent papers. The subject of the first paper is calculating thresholds for epidemic outbreaks on dynamic networks, where the disease spread is modelled by percolation. In the paper, known analytical solutions for the epidemic thresholds were extended to a class of dynamically evolving networks; additionally, the effects of finite size of the network on the magnitude of the epidemic were studied numerically. The subject of the second and third paper is the static and dynamic properties of two diametrically opposed random walks on model highly symmetric deterministic graphs. Specifically, we analytically and numerically find the stationary states and relaxation times of the ordinary, diffusive random walk and the maximal-entropy random walk. The results provide insight into localisation of random walks or their trapping in isolated regions of networks. Finally, in the fourth and fifth paper, we examine the utility of random walks in detecting topological features of complex networks. In particular, we study properties of the centrality measures (roughly speaking, the ranking of vertices) based on random walks, as well as we conduct a systematic comparative study of random-walk based methods of detecting modular structure of networks. These studies thus aimed at specific problems in modelling and analysis of complex networks, including theoretical examination of the ways the behaviour of random processes intertwines with the structure of complex networks.\n
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\n \n\n \n \n \n \n \n \n Maximal entropy random walk in community detection.\n \n \n \n \n\n\n \n Ochab, J.; and Burda, Z.\n\n\n \n\n\n\n The European Physical Journal Special Topics, 216(1): 73–81. 2013.\n \n\n\n\n
\n\n\n\n \n \n \"MaximalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ochab_maximal_2013,\n\ttitle = {Maximal entropy random walk in community detection},\n\tvolume = {216},\n\tcopyright = {All rights reserved},\n\tissn = {1951-6355},\n\turl = {http://dx.doi.org/10.1140/epjst/e2013-01730-6},\n\tdoi = {10.1140/epjst/e2013-01730-6},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {The European Physical Journal Special Topics},\n\tauthor = {Ochab, J.K. and Burda, Z.},\n\tyear = {2013},\n\tpages = {73--81},\n}\n\n
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\n  \n 2012\n \n \n (2)\n \n \n
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\n \n\n \n \n \n \n \n \n Maximal-entropy random walk unifies centrality measures.\n \n \n \n \n\n\n \n Ochab, J. K.\n\n\n \n\n\n\n Phys. Rev. E, 86(6): 066109. 2012.\n \n\n\n\n
\n\n\n\n \n \n \"Maximal-entropyPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ochab_maximal-entropy_2012,\n\ttitle = {Maximal-entropy random walk unifies centrality measures},\n\tvolume = {86},\n\tcopyright = {All rights reserved},\n\turl = {http://link.aps.org/doi/10.1103/PhysRevE.86.066109},\n\tdoi = {10.1103/PhysRevE.86.066109},\n\tnumber = {6},\n\tjournal = {Phys. Rev. E},\n\tauthor = {Ochab, J. K.},\n\tyear = {2012},\n\tpages = {066109},\n}\n\n
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\n \n\n \n \n \n \n \n \n Exact solution for statics and dynamics of maximal-entropy random walks on Cayley trees.\n \n \n \n \n\n\n \n Ochab, J. K.; and Burda, Z.\n\n\n \n\n\n\n Phys. Rev. E, 85(2): 021145. 2012.\n \n\n\n\n
\n\n\n\n \n \n \"ExactPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ochab_exact_2012,\n\ttitle = {Exact solution for statics and dynamics of maximal-entropy random walks on {Cayley} trees},\n\tvolume = {85},\n\tcopyright = {All rights reserved},\n\turl = {http://link.aps.org/doi/10.1103/PhysRevE.85.021145},\n\tdoi = {10.1103/PhysRevE.85.021145},\n\tnumber = {2},\n\tjournal = {Phys. Rev. E},\n\tauthor = {Ochab, J. K. and Burda, Z.},\n\tyear = {2012},\n\tpages = {021145},\n}\n\n
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\n  \n 2011\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Shift of percolation thresholds for epidemic spread between static and dynamic small-world networks.\n \n \n \n \n\n\n \n Ochab, J.; and Góra, P.\n\n\n \n\n\n\n The European Physical Journal B, 81(3): 373–379. 2011.\n \n\n\n\n
\n\n\n\n \n \n \"ShiftPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ochab_shift_2011,\n\ttitle = {Shift of percolation thresholds for epidemic spread between static and dynamic small-world networks},\n\tvolume = {81},\n\tcopyright = {All rights reserved},\n\tissn = {1434-6028},\n\turl = {http://dx.doi.org/10.1140/epjb/e2011-10975-6},\n\tdoi = {10.1140/epjb/e2011-10975-6},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {The European Physical Journal B},\n\tauthor = {Ochab, J.K. and Góra, P.F.},\n\tyear = {2011},\n\tpages = {373--379},\n}\n\n
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\n  \n 2010\n \n \n (1)\n \n \n
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\n \n\n \n \n \n \n \n \n Synchronization of Coupled Oscillators in a Local One-dimensional Kuramoto Model.\n \n \n \n \n\n\n \n Ochab, J; and Góra, P F\n\n\n \n\n\n\n Acta Physica Polonica B Proceedings Supplement, 3(2): 453–462. 2010.\n \n\n\n\n
\n\n\n\n \n \n \"SynchronizationPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ochab_synchronization_2010,\n\tseries = {Proceedings {Supplement}},\n\ttitle = {Synchronization of {Coupled} {Oscillators} in a {Local} {One}-dimensional {Kuramoto} {Model}},\n\tvolume = {3},\n\tcopyright = {All rights reserved},\n\tissn = {2082-7865},\n\turl = {https://www.actaphys.uj.edu.pl/S/3/2/453/pdf},\n\tlanguage = {en},\n\tnumber = {2},\n\tjournal = {Acta Physica Polonica B Proceedings Supplement},\n\tauthor = {Ochab, J and Góra, P F},\n\tyear = {2010},\n\tkeywords = {⛔ No DOI found},\n\tpages = {453--462},\n}\n\n
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