366 research outputs found

    Adipositas von Kindern und Jugendlichen: Risiken, Ursachen und Therapie aus psychologischer Sicht

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    Zusammenfassung: Seit den 1990er-Jahren steigt der Anteil an übergewichtigen oder adipösen Kindern und Jugendlichen in Deutschland und Europa stark an. Etwa ein Drittel der adipösen Vorschulkinder und etwa die Hälfte der Schulkinder sind als Erwachsene adipös; die ökonomischen, medizinischen und psychosozialen Folgen sind erheblich. Der vorliegende Beitrag gibt einen Überblick über die psychischen Risikofaktoren und Ursachen von Adipositas bei Kindern und Jugendlichen. Hierzu zählen zum Beispiel eine Komorbidität mit psychischen Störungen, Stigmatisierung, ein schwieriges Verhältnis zu Gleichaltrigen, zur Familie, andere Umweltfaktoren und die genetische Veranlagung in Wechselwirkung mit dem Verhalten. Das Verständnis der Risikofaktoren und Ursachen für Adipositas ist die Basis für psychologische Therapieansätze. Es werden psychologische Aspekte der Adipositas, wie die Rolle von Motivation und Impulsivität, besprochen und verhaltenstherapeutische Komponenten sowie Interventionsmodalitäten im Rahmen der Therapie vorgestellt. Ein besseres Verständnis psychischer Faktoren ist notwendig, um effektivere Interventionen und langfristigere Behandlungserfolge zu erreichen. Dies gilt auch für Veränderungen der sozialen, medialen und physischen Umweltstruktur mit dem Ziel, gesunde Ernährung und körperliche Aktivität zu begünstige

    Electric field sensing with a scanning fiber-coupled quantum dot

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    We demonstrate the application of a fiber-coupled quantum-dot-in-a-tip as a probe for scanning electric field microscopy. We map the out-of-plane component of the electric field induced by a pair of electrodes by measurement of the quantum-confined Stark effect induced on a quantum dot spectral line. Our results are in agreement with finite element simulations of the experiment. Furthermore, we present results from analytic calculations and simulations which are relevant to any electric field sensor embedded in a dielectric tip. In particular, we highlight the impact of the tip geometry on both the resolution and sensitivity.Comment: 10 pages, 4 figure

    Quantum dot opto-mechanics in a fully self-assembled nanowire

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    We show that fully self-assembled optically-active quantum dots (QDs) embedded in MBE-grown GaAs/AlGaAs core-shell nanowires (NWs) are coupled to the NW mechanical motion. Oscillations of the NW modulate the QD emission energy in a broad range exceeding 14 meV. Furthermore, this opto-mechanical interaction enables the dynamical tuning of two neighboring QDs into resonance, possibly allowing for emitter-emitter coupling. Both the QDs and the coupling mechanism -- material strain -- are intrinsic to the NW structure and do not depend on any functionalization or external field. Such systems open up the prospect of using QDs to probe and control the mechanical state of a NW, or conversely of making a quantum non-demolition readout of a QD state through a position measurement.Comment: 20 pages, 6 figure

    Prevalence in Primary School Youth of Pica and Rumination Behavior: The Understudied Feeding

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    Objective: Little epidemiological evidence exists on rumination disorder behavior (RB) and pica behavior (PB). We examined prevalence of RB and PB and presence of comorbid feeding/eating disorder symptoms among school-aged children. Methods: In elementary schools in Switzerland, 1,430 children (54.0% female) ages seven to 13 completed Eating Disorder Examination-Questionnaire for children (ChEDE-Q) and Eating Disturbances in Youth Questionnaire (EDY-Q). Results: EDY-Q data behavior frequency showed 9.7% reported RB only, 10.0% reported PB only, and 3.1% reported RB+PB (≥1 on 0-6 Likert scale). At a clinical cut-off score of ≥4 (at least “often true”), 1.7% had RB only, 3.8% had PB only, and 1.1% had RB+PB. Avoidant/restrictive food intake disorder symptoms were most common in those with RB+PB, and more common in those with RB or PB than those without. Degree of eating disorder symptoms (by ChEDE-Q) over the past 28 days were similar among those with RB, PB, or RB+PB, but less common in those without RB or PB. Discussion: RB and PB were commonly reported in our sample of school-aged children, even at a potential clinically significant cut-off. Our findings also suggest that degree of eating disorder symptom comorbidity is similar between those with RB and PB

    An artificial Rb atom in a semiconductor with lifetime-limited linewidth

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    We report results important for the creation of a best-of-both-worlds quantum hybrid system consisting of a solid-state source of single photons and an atomic ensemble as quantum memory. We generate single photons from a GaAs quantum dot (QD) frequency-matched to the Rb D2-transitions and then use the Rb transitions to analyze spectrally the quantum dot photons. We demonstrate lifetime-limited QD linewidths (1.48 GHz) with both resonant and non-resonant excitation. The QD resonance fluorescence in the low power regime is dominated by Rayleigh scattering, a route to match quantum dot and Rb atom linewidths and to shape the temporal wave packet of the QD photons. Noise in the solid-state environment is relatively benign: there is a blinking of the resonance fluorescence at MHz rates but negligible upper state dephasing of the QD transition. We therefore establish a close-to-ideal solid-state source of single photons at a key wavelength for quantum technologies

    Resonant driving of a single photon emitter embedded in a mechanical oscillator

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    Coupling a microscopic mechanical resonator to a nanoscale quantum system enables control of the mechanical resonator via the quantum system and vice-versa. The coupling is usually achieved through functionalization of the mechanical resonator, but this results in additional mass and dissipation channels. An alternative is an intrinsic coupling based on strain. Here we employ a monolithic semiconductor system: the nanoscale quantum system is a semiconductor quantum dot (QD) located inside a nanowire. We demonstrate the resonant optical driving of the QD transition in such a structure. The noise spectrum of the resonance fluorescence signal, recorded in the single-photon counting regime, reveals a coupling to mechanical modes of different types. We measure a sensitivity to displacement of 65 fm/root Hz limited by charge noise in the device. Finally, we use thermal excitation of the different modes to determine the location of the QD within the trumpet, and calculate the contribution of the Brownian motion to the dephasing of the emitter
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