2,024 research outputs found

    Typical Borel measures on [0,1]d[0,1]d satisfy a multifractal formalism

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    In this article, we prove that in the Baire category sense, measures supported by the unit cube of Rd\R^d typically satisfy a multifractal formalism. To achieve this, we compute explicitly the multifractal spectrum of such typical measures μ\mu. This spectrum appears to be linear with slope 1, starting from 0 at exponent 0, ending at dimension dd at exponent dd, and it indeed coincides with the Legendre transform of the LqL^q-spectrum associated with typical measures μ\mu.Comment: 17 pages. To appear in Nonlinearit

    Development of a watercourse-based model to assess the canal water supply at the farm level

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    Irrigation systems / Irrigation canals / Water supply / Watercourses / Water allocation / Irrigation scheduling / Hydraulics / Models / Seepage loss / Flumes / Calibrations / Discharges / Performance indexes / Pakistan / Indus River

    Resting EEG Microstates and Autonomic Heart Rate Variability Do Not Return to Baseline One Hour After a Submaximal Exercise.

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    Recent findings suggest that an acute physical exercise modulates the temporal features of the EEG resting microstates, especially the microstate map C duration and relative time coverage. Microstate map C has been associated with the salience resting state network, which is mainly structured around the insula and cingulate, two brain nodes that mediate cardiovascular arousal and interoceptive awareness. Heart rate variability (HRV) is dependent on the autonomic balance; specifically, an increase in the sympathetic (or decrease in the parasympathetic) tone will decrease variability while a decrease in the sympathetic (or increase in the parasympathetic) tone will increase variability. Relying on the functional interaction between the autonomic cardiovascular activity and the salience network, this study aims to investigate the effect of exercise on the resting microstate and the possible interplay with this autonomic cardiovascular recovery after a single bout of endurance exercise. Thirty-eight young adults performed a 25-min constant-load cycling exercise at an intensity that was subjectively perceived as "hard." The microstate temporal features and conventional time and frequency domain HRV parameters were obtained at rest for 5 min before exercise and at 5, 15, 30, 45, and 60 min after exercise. Compared to the baseline, all HRV parameters were changed 5 min after exercise cessation. The mean durations of microstate B and C, and the frequency of occurrence of microstate D were also changed immediately after exercise. A long-lasting effect was found for almost all HRV parameters and for the duration of microstate C during the hour following exercise, indicating an uncompleted recovery of the autonomic cardiovascular system and the resting microstate. The implication of an exercise-induced afferent neural traffic is discussed as a potential modulator of both the autonomic regulation of heart rate and the resting EEG microstate

    Architecture for Multi-Technology Real-Time Location Systems

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    [Abstract]The rising popularity of location-based services has prompted considerable research in the field of indoor location systems. Since there is no single technology to support these systems, it is necessary to consider the fusion of the information coming from heterogeneous sensors. This paper presents a software architecture designed for a hybrid location system where we can merge information from multiple sensor technologies. The architecture was designed to be used by different kinds of actors independently and with mutual transparency: hardware administrators, algorithm developers and user applications. The paper presents the architecture design, work-flow, case study examples and some results to show how different technologies can be exploited to obtain a good estimation of a target position.[Resumen]El aumento de la popularidad de servicios localización-basados ha llevado a una investigación considerable en el campo de los sistemas de localización en interiores. Ya no hay solo tecnología para soportar estos sistemas, es necesario considerar la fusión de la información proveniente de sensores heterogéneos. Este papel presenta una arquitectura de software diseñada para un sistema de localización de híbridos donde nosotros podemos combinar información de múltiples tecnologías de sensor. La arquitectura fue diseñada para ser utilizada por diferentes tipos de actores independientemente y con transparencia mutua: los administradores de hardware, los desarrolladores de algoritmo y aplicaciones de usuario. El documento presenta el diseño de arquitectura, flujo de trabajo, ejemplos de estudios de caso y algunos resultados para mostrar cómo las diferentes tecnologías pueden explotarse para obtener una buena estimación de la posición de destinoMinisterio de Industria, Turismo y Comercio; IPT-020000-2010-35Ministerio de Educación y Ciencia; TEC2010-19545-C04-01Ministerio de Educación y Ciencia; CSD2008-0001

    Artificial Rheotaxis

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    Motility is a basic feature of living microorganisms, and how it works is often determined by environmental cues. Recent efforts have focused on develop- ing artificial systems that can mimic microorganisms, and in particular their self-propulsion. Here, we report on the design and characterization of syn- thetic self-propelled particles that migrate upstream, known as positive rheo- taxis. This phenomenon results from a purely physical mechanism involving the interplay between the polarity of the particles and their alignment by a viscous torque. We show quantitative agreement between experimental data and a simple model of an overdamped Brownian pendulum. The model no- tably predicts the existence of a stagnation point in a diverging flow. We take advantage of this property to demonstrate that our active particles can sense and predictably organize in an imposed flow. Our colloidal system represents an important step towards the realization of biomimetic micro-systems withthe ability to sense and respond to environmental changesComment: Published in Science Advances [Open access journal of Science Magazine

    "El café tiene cafeína y nos despierta, nos da energía" : concepciones sobre la energía química, una buena razón para poner de acuerdo a los profesores de Física y Química y ciencias Naturales

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    A research was carried on students' conceptions about chemical energy. The experimental sample were students from primary level to university. Word association tasks and a paper and pencil question were used as instruments for collecting data. The test revealed that some students share certain alternative conceptions about chemical energy, and that most of them use ideas about chemical energy in a similar way to what people without formal instruction in this issue would do. Some implications for science teaching-learning are suggested

    Activation and inhibition of bimanual movements in school-aged children

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    The development of motor activation and inhibition was compared in 6-to-12 year-olds. Children had to initiate or stop the externally paced movements of one hand, while maintaining that of the other hand. The time needed to perform the switching task (RT) and the spatio-temporal variables show different agerelated evolutions depending on the coordination pattern (inor anti-phase) and the type of transition (activation, selective inhibition, non selective inhibition) required. In the anti-phase mode, activation perturbs the younger subjects' responses while temporal and spatial stabilities transiently decrease around 9 years when activating in the in-phase mode. Aged-related changes differed between inhibition and activation in the antiphase mode, suggesting either the involvement of distinct neural networks or the existence of a single network that is reorganized. In contrast, stopping or adding one hand in the in-phase mode shows similar aged-related improvement. We suggest that selectively stopping or activating one arm during symmetrical coordination rely on the two faces of a common processing in which activation could be the release of inhibitio

    Quantifying entropy production in active fluctuations of the hair-cell bundle from time irreversibility and uncertainty relations

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    We introduce lower bounds for the rate of entropy production of an active stochastic process by quantifying the irreversibility of stochastic traces obtained from mesoscopic degrees of freedom. Our measures of irreversibility reveal signatures of time's arrow and provide bounds for entropy production even in the case of active fluctuations that have no drift. We apply these irreversibility measures to experimental recordings of spontaneous hair-bundle oscillations in mechanosensory hair cells from the ear of the bullfrog. By analyzing the fluctuations of only the tip position of hair bundles, we reveal irreversibility in active oscillations and estimate an associated rate of entropy production of at least similar to 3k (B)/s, on average. Applying thermodynamic uncertainty relations, we predict that measuring both the tip position of the hair bundle and the mechano-electrical transduction current that enters the hair cell leads to tighter lower bounds for the rate of entropy production, up to similar to 10(3) k (B)/s in the oscillatory regime
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