602 research outputs found

    Detection of time reversibility in time series by ordinal patterns analysis

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    Time irreversibility is a common signature of nonlinear processes, and a fundamental property of non-equilibrium systems driven by non-conservative forces. A time series is said to be reversible if its statistical properties are invariant regardless of the direction of time. Here we propose the Time Reversibility from Ordinal Patterns method (TiROP) to assess time-reversibility from an observed finite time series. TiROP captures the information of scalar observations in time forward, as well as its time-reversed counterpart by means of ordinal patterns. The method compares both underlying information contents by quantifying its (dis)-similarity via Jensen-Shannon divergence. The statistic is contrasted with a population of divergences coming from a set of surrogates to unveil the temporal nature and its involved time scales. We tested TiROP in different synthetic and real, linear and non linear time series, juxtaposed with results from the classical Ramsey's time reversibility test. Our results depict a novel, fast-computation, and fully data-driven methodology to assess time-reversibility at different time scales with no further assumptions over data. This approach adds new insights about the current non-linear analysis techniques, and also could shed light on determining new physiological biomarkers of high reliability and computational efficiency.Comment: 8 pages, 5 figures, 1 tabl

    Beware of the Small-World neuroscientist!

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    The SW has undeniably been one of the most popular network descriptors in the neuroscience literature. Two main reasons for its lasting popularity are its apparent ease of computation and the intuitions it is thought to provide on how networked systems operate. Over the last few years, some pitfalls of the SW construct and, more generally, of network summary measures, have widely been acknowledged

    Hacia una crítica del positivismo en la historia de las organizaciones

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    El comportamiento humano actual es un reflejo de su experiencia y evolución frente a nuevos retos, en donde la prioridad se ha basado en satisfacer sus principales necesidades, las cuales se han complejizado a medida que la vida ha demandado nuevas prácticas, a costa de cualquier sacrificio, sea éste de carácter humano, material o ambiental. A través de este documento de investigación se evidencia un corto recuento de los hechos históricos más relevantes asociados con las organizaciones, en donde la práctica crematística y la obtención de poder han sido la principal causa en los conflictos más caóticos de nuestra humanidad debido a que estamos inmersos aún en el paradigma del positivismo.The current human behavior is a reflection of the human own experience and evolution in front of new challenges, in which the central point has been based in satisfying our main needs. These needs have been more complex at the same time as life demands new practices at the expenses of any human, material or environmental sacrifice. Throughout this research document a short report of the most relevant historical events related with organizations is evidenced, where the chrematistic practices and the power struggle have been the main cause of the most chaotic human conflicts, because we continue to be immersed in the positivism paradigm

    Evaluating the effect of aging on interference resolution with time-varying complex networks analysis

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    In this study we used graph theory analysis to investigate age-related reorganization of functional networks during the active maintenance of information that is interrupted by external interference. Additionally, we sought to investigate network differences before and after averaging network parameters between both maintenance and interference windows. We compared young and older adults by measuring their magnetoencephalographic recordings during an interference-based working memory task restricted to successful recognitions. Data analysis focused on the topology/temporal evolution of functional networks during both the maintenance and interference windows. We observed that: (a) Older adults require higher synchronization between cortical brain sites in order to achieve a successful recognition, (b) The main differences between age groups arise during the interference window, (c) Older adults show reduced ability to reorganize network topology when interference is introduced, and (d) Averaging network parameters leads to a loss of sensitivity to detect age differences. © 2015 Ariza, Solesio-Jofre, Martínez, Pineda-Pardo, Niso, Maestú and Buldú

    Evaluating the effect of aging on interference resolution with time-varying complex networks analysis

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    In this study we used graph theory analysis to investigate age-related reorganization of functional networks during the active maintenance of information that is interrupted by external interference. Additionally, we sought to investigate network differences before and after averaging network parameters between both maintenance and interference windows. We compared young and older adults by measuring their magnetoencephalographic recordings during an interference-based working memory task restricted to successful recognitions. Data analysis focused on the topology/temporal evolution of functional networks during both the maintenance and interference windows. We observed that: (a) Older adults require higher synchronization between cortical brain sites in order to achieve a successful recognition, (b) The main differences between age groups arise during the interference window, (c) Older adults show reduced ability to reorganize network topology when interference is introduced, and (d) Averaging network parameters leads to a loss of sensitivity to detect age differencesThis work has been supported by the Spanish MINECO under project [FIS2013-41057], as well as Fundación Carolina Doctoral Scholarship Program and Colciencias Doctoral Program 56

    Evaluating the effect of aging on interference resolution with time-varying complex networks analysis

    Get PDF
    In this study we used graph theory analysis to investigate age-related reorganization of functional networks during the active maintenance of information that is interrupted by external interference. Additionally, we sought to investigate network differences before and after averaging network parameters between both maintenance and interference windows. We compared young and older adults by measuring their magnetoencephalographic recordings during an interference-based working memory task restricted to successful recognitions. Data analysis focused on the topology/temporal evolution of functional networks during both the maintenance and interference windows. We observed that: (a) Older adults require higher synchronization between cortical brain sites in order to achieve a successful recognition, (b) The main differences between age groups arise during the interference window, (c) Older adults show reduced ability to reorganize network topology when interference is introduced, and (d) Averaging network parameters leads to a loss of sensitivity to detect age differencesThis work has been supported by the Spanish MINECO under project [FIS2013-41057], as well as Fundación Carolina Doctoral Scholarship Program and Colciencias Doctoral Program 56
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