1,613 research outputs found

    Single-atom control of the optoelectronic response in sub-nanometric cavities

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    By means of ab-initio time dependent density functional theory calculations carried out on an prototypical hybrid plasmonic device (two metallic nanoparticles bridged by a one-atom junction), we demonstrate the strong interplay between photoinduced excitation of localized surface plasmons and electron transport through the single atom. Such an interplay is remarkably sensitive to the atomic orbitals of the junction. Therefore, we show the possibility of a twofold tuning (plasmonic response and photoinduced current across the juntion) just by changing a single atom in the device.Comment: 5 pages, 5 figure

    The key role of off-axis singularities in free-space vortex transmutation

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    We experimentally demonstrate the generation of off-axis phase singularities in a vortex transmutation process induced by the breaking of rotational symmetry. The process takes place in free space by launching a highly-charged vortex, owning full rotational symmetry, into a linear thin diffractive element presenting discrete rotational symmetry. It is shown that off-axis phase singularities follow straight dark rays bifurcating from the symmetry axis. This phenomenon may provide new routes towards the spatial control of multiple phase singularities for applications in atom trapping and particle manipulation.Comment: 4 pages, 4 figures, to appear in Applied Physics B: Lasers and Optic

    Bayesian Sequential Track Formation

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    This paper presents a theoretical framework for track building in multiple-target scenarios from the Bayesian point of view. It is assumed that the number of targets is fixed and known. We propose two optimal methods for building tracks sequentially. The first one uses the labelling of the current multitarget state estimate that minimizes the mean-square labeled optimal subpatternassignment error. This method requires knowledge of the posterior density of the vector-valued state. The second assigns the labeling that maximizes the probability that the current multi-targetstate estimate is optimally linked with the available tracks at the previous time step. In this case, we only require knowledge of the random finite-set posterior density without labels

    Acculturation, Gender, and Active Life Expectancy in the Mexican-Origin Population

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    Objective—This study examines the potential effects of nativity and acculturation on active life expectancy (ALE) among Mexican-origin elders. Method—We employ 17 years of data from the Hispanic Established Population for the Epidemiologic Study of the Elderly to calculate ALE at age 65 with and without disabilities. Results—Native-born males and foreign-born females spend a larger fraction of their elderly years with activities of daily living (ADL) disability. Conversely, both foreign-born males and females spend a larger fraction of their remaining years with instrumental activities of daily life (IADL) disability than the native-born. In descriptive analysis, women with low acculturation report higher ADL and IADL disability. Men manifest similar patterns for IADLs. Discussion—Although foreign-born elders live slightly longer lives, they do so with more years spent in a disabled state. Given the rapid aging of the Mexican-origin population, the prevention and treatment of disabilities, particularly among the foreign born, should be a major public health priority
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