1,937 research outputs found

    Reply to "Comment on `Performance of different synchronization measures in real data: A case study on electroencephalographic signals'"

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    We agree with the Comment by Nicolaou and Nasuto about the utility of mutual information (MI) when properly estimated and we also concur with their view that the estimation based on k nearest neighbors gives optimal results. However, we claim that embedding parameters can indeed change MI results, as we show for the electroencephalogram data sets of our original study and for coupled chaotic systems. Furthermore, we show that proper embedding can actually improve the estimation of MI with the k nearest neighbors algorithm

    Fluvic acid carbon as a dignostic feature for agricultural soil evaluation

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    The fluvic acid fraction in considered to be sensitive to agronomic and environment factors. Therefore, the objectives of this study were to evaluate total carbon (TC) and fluvic acid carbon (FC) contens and to establish a possible relationship between the FC fraction and coarse organic matter in agricultural soils (CTVs), (ii) conservation tilled soils (CSTs), and (iii) virgins soils (VIRs) from a wide region in Argentina. The investigation includes 114 surface samples of Hapludolls, Haplustolls, and Entisols ranging in texture from sand to slit loam. In 29 selected samples, two separate soil mineral fraction were used (<0.05 mm and 0.1-2 mm) to determinate FC and TC contents. No statistically significant differences were found in TC contents in the fine fraction < 0.05 mm between VlRs, CSTs, and CVTs; however, FC contents were higher in VIRs than in CSTs and CVTs at the 0.05 probability level. In addition" statistically significant differences (P< 0.05) observed in FC contents among all three treatments in the coarse fraction 0.1-2 mm confirm that the FC fraction Is more influenced by the farming-system thn Is TC. Moreover, FC I TC ratios tended to increase under agricultural land use (CVTs > CSTs > VIRs), and this radio also Increased from finer textured soils to creaser tent was highly related to recently incorporated organic residues.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Soil Science 1999; Vol 164: 57-6

    Analytic results for NN particles with 1/r21/r^2 interaction in two dimensions and an external magnetic field

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    The 2N2N-dimensional quantum problem of NN particles (e.g. electrons) with interaction β/r2\beta/r^2 in a two-dimensional parabolic potential ω0\omega_0 (e.g. quantum dot) and magnetic field BB, reduces exactly to solving a (2N4)(2N-4)-dimensional problem which is independent of BB and ω0\omega_0. An exact, infinite set of relative mode excitations are obtained for any NN. The N=3N=3 problem reduces to that of a ficticious particle in a two-dimensional, non-linear potential of strength β\beta, subject to a ficticious magnetic field BficJB_{\rm fic}\propto J, the relative angular momentum.Comment: To appear in Physical Review Letters (in press). RevTeX file. Two figures available from [email protected] or [email protected]

    Probing ferroelectricity in highly conducting materials through their elastic response: persistence of ferroelectricity in metallic BaTiO3-d

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    The question whether ferroelectricity (FE) may coexist with a metallic or highly conducting state, or rather it must be suppressed by the screening from the free charges, is the focus of a rapidly increasing number of theoretical studies and is finally receiving positive experimental responses. The issue is closely related to the thermoelectric and multiferroic (also magnetic) applications of FE materials, where the electrical conductivity is required or spurious. In these circumstances, the traditional methods for probing ferroelectricity are hampered or made totally ineffective by the free charges, which screen the polar response to an external electric field. This fact may explain why more than 40 years passed between the first proposals of FE metals and the present experimental and theoretical activity. The measurement of the elastic moduli, Young's modulus in the present case, versus temperature is an effective method for studying the influence of doping on a FE transition because the elastic properties are unaffected by electrical conductivity. In this manner, it is shown that the FE transitions of BaTiO3-d are not suppressed by electron doping through O vacancies; only the onset temperatures are depressed, but the magnitudes of the softenings, and hence of the piezoelectric activity, are initially even increased

    Millimetre spectral indices of transition disks and their relation to the cavity radius

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    Transition disks are protoplanetary disks with inner depleted dust cavities and excellent candidates to investigate the dust evolution under the existence of a pressure bump. A pressure bump at the outer edge of the cavity allows dust grains from the outer regions to stop their rapid inward migration towards the star and efficiently grow to millimetre sizes. Dynamical interactions with planet(s) have been one of the most exciting theories to explain the clearing of the inner disk. We look for evidence of the presence of millimetre dust particles in transition disks by measuring their spectral index with new and available photometric data. We investigate the influence of the size of the dust depleted cavity on the disk integrated millimetre spectral index. We present the 3mm photometric observations carried out with PdBI of four transition disks: LkHa330, UXTauA, LRLL31, and LRLL67. We use available values of their fluxes at 345GHz to calculate their spectral index, as well as the spectral index for a sample of twenty transition disks. We compare the observations with two kind of models. In the first set of models, we consider coagulation and fragmentation of dust in a disk in which a cavity is formed by a massive planet located at different positions. The second set of models assumes disks with truncated inner parts at different radius and with power-law dust size distributions, where the maximum size of grains is calculated considering turbulence as the source of destructive collisions. We show that the integrated spectral index is higher for transition disks than for regular protoplanetary disks. For transition disks, the probability that the measured spectral index is positively correlated with the cavity radius is 95%. High angular resolution imaging of transition disks is needed to distinguish between the dust trapping scenario and the truncated disk case.Comment: Accepted for publication in A&A, including language editio

    Two and three electrons in a quantum dot: 1/|J| - expansion

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    We consider systems of two and three electrons in a two-dimensional parabolic quantum dot. A magnetic field is applied perpendicularly to the electron plane of motion. We show that the energy levels corresponding to states with high angular momentum, J, and a low number of vibrational quanta may be systematically computed as power series in 1/|J|. These states are relevant in the high-B limit.Comment: LaTeX, 15 pages,6 postscript figure

    Kullback-Leibler and Renormalized Entropy: Applications to EEGs of Epilepsy Patients

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    Recently, renormalized entropy was proposed as a novel measure of relative entropy (P. Saparin et al., Chaos, Solitons & Fractals 4, 1907 (1994)) and applied to several physiological time sequences, including EEGs of patients with epilepsy. We show here that this measure is just a modified Kullback-Leibler (K-L) relative entropy, and it gives similar numerical results to the standard K-L entropy. The latter better distinguishes frequency contents of e.g. seizure and background EEGs than renormalized entropy. We thus propose that renormalized entropy might not be as useful as claimed by its proponents. In passing we also make some critical remarks about the implementation of these methods.Comment: 15 pages, 4 Postscript figures. Submitted to Phys. Rev. E, 199

    Commutative CC^*-algebras of Toeplitz operators on complex projective spaces

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    We prove the existence of commutative CC^*-algebras of Toeplitz operators on every weighted Bergman space over the complex projective space Pn(C)\mathbb{P}^n(\mathbb{C}). The symbols that define our algebras are those that depend only on the radial part of the homogeneous coordinates. The algebras presented have an associated pair of Lagrangian foliations with distinguished geometric properties and are closely related to the geometry of Pn(C)\mathbb{P}^n(\mathbb{C})

    The nexus between climate change, ecosystem services and human health: Towards a conceptual framework

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    This paper addresses the impact that changes in natural ecosystems can have on health and wellbeing focusing on the potential co-benefits that green spaces could provide when introduced as climate change adaptation measures. Ignoring such benefits could lead to sub-optimal planning and decision-making. A conceptual framework, building on the ecosystem-enriched Driver, Pressure, State, Exposure, Effect, Action model (eDPSEEA), is presented to aid in clarifying the relational structure between green spaces and human health, taking climate change as the key driver. The study has the double intention of (i) summarising the literature with a special emphasis on the ecosystem and health perspectives, as well as the main theories behind these impacts, and (ii) modelling these findings into a framework that allows for multidisciplinary approaches to the underlying relations between human health and green spaces. The paper shows that while the literature based on the ecosystem perspective presents a well-documented association between climate, health and green spaces, the literature using a health-based perspective presents mixed evidence in some cases. The role of contextual factors and the exposure mechanism are rarely addressed. The proposed framework could serve as a multidisciplinary knowledge platform for multi-perspecitve analysis and discussion among experts and stakeholders, as well as to support the operationalization of quantitative assessment and modelling exercises. © 2018 The AuthorsAuthors would like to acknowledge the support provided by two research projects: Horizon 2020 research project INHERIT (INter-sectoral Health and Environment Research for InnovaTion); and EU COST Action IS1204: Tourism, Wellbeing and Ecosystem Services (TObeWELL)

    The nexus between climate change, ecosystem services and human health: Towards a conceptual framework

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    This is the final version. Available on open access from Elsevier via the DOI in this recordThis paper addresses the impact that changes in natural ecosystems can have on health and wellbeing focusing on the potential co-benefits that green spaces could provide when introduced as climate change adaptation measures. Ignoring such benefits could lead to sub-optimal planning and decision-making. A conceptual framework, building on the ecosystem-enriched Driver, Pressure, State, Exposure, Effect, Action model (eDPSEEA), is presented to aid in clarifying the relational structure between green spaces and human health, taking climate change as the key driver. The study has the double intention of (i) summarising the literature with a special emphasis on the ecosystem and health perspectives, as well as the main theories behind these impacts, and (ii) modelling these findings into a framework that allows for multidisciplinary approaches to the underlying relations between human health and green spaces. The paper shows that while the literature based on the ecosystem perspective presents a well-documented association between climate, health and green spaces, the literature using a health-based perspective presents mixed evidence in some cases. The role of contextual factors and the exposure mechanism are rarely addressed. The proposed framework could serve as a multidisciplinary knowledge platform for multi-perspecitve analysis and discussion among experts and stakeholders, as well as to support the operationalization of quantitative assessment and modelling exercises.European Union Horizon 202
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