1,618 research outputs found

    Real-time monitoring of stress evolution during thin film growth by in situ substrate curvature measurement

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    Strain engineering is the art of inducing controlled lattice distortions in a material to modify specific physicochemical properties. Strain engineering is applied for basic fundamental studies of physics and chemistry of solids but also for device fabrication through the development of materials with new functionalities. Thin films are one of the most important tools for strain engineering. Thin films can in fact develop large strain due to the crystalline constrains at the interface with the substrate and/or as the result of specific morphological features that can be selected by an appropriate tuning of the deposition parameters. Within this context, the in situ measurement of the substrate curvature is a powerful diagnostic tool allowing a real time monitoring of the stress state of the growing film. This manuscript reviews a few recent applications of this technique and presents new measurements that point out the great potentials of the substrate curvature measurement in strain engineering. Our study also shows how, due to the high sensitivity of the technique, the correct interpretation of the results can be in certain cases not trivial and require complementary characterizations and an accurate knowledge of the physicochemical properties of the materials under investigation

    Orbital parameters of extrasolar planets derived from polarimetry

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    Polarimetry of extrasolar planets becomes a new tool for their investigation, which requires the development of diagnostic techniques and parameter case studies. Our goal is to develop a theoretical model which can be applied to interpret polarimetric observations of extrasolar planets. Here we present a theoretical parameter study that shows the influence of the various involved parameters on the polarization curves. Furthermore, we investigate the robustness of the fitting procedure. We employ the physics of Rayleigh scattering to obtain polarization curves of an unresolved extrasolar planet. Calculations are made for two cases: (i) assuming an angular distribution for the intensity of the scattered light as from a Lambert sphere and for polarization as from a Rayleigh-type scatterer, and (ii) assuming that both the intensity and polarization of the scattered light are distributed according to the Rayleigh law. We show that the difference between these two cases is negligible for the shapes of the polarization curves. In addition, we take the size of the host star into account, which is relevant for hot Jupiters orbiting giant stars

    Cosmological constraints from noisy convergence maps through deep learning

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    Deep learning is a powerful analysis technique that has recently been proposed as a method to constrain cosmological parameters from weak lensing mass maps. Due to its ability to learn relevant features from the data, it is able to extract more information from the mass maps than the commonly used power spectrum, and thus achieve better precision for cosmological parameter measurement. We explore the advantage of Convolutional Neural Networks (CNN) over the power spectrum for varying levels of shape noise and different smoothing scales applied to the maps. We compare the cosmological constraints from the two methods in the ΩMσ8\Omega_M-\sigma_8 plane for sets of 400 deg2^2 convergence maps. We find that, for a shape noise level corresponding to 8.53 galaxies/arcmin2^2 and the smoothing scale of σs=2.34\sigma_s = 2.34 arcmin, the network is able to generate 45% tighter constraints. For smaller smoothing scale of σs=1.17\sigma_s = 1.17 the improvement can reach 50%\sim 50 \%, while for larger smoothing scale of σs=5.85\sigma_s = 5.85, the improvement decreases to 19%. The advantage generally decreases when the noise level and smoothing scales increase. We present a new training strategy to train the neural network with noisy data, as well as considerations for practical applications of the deep learning approach.Comment: 17 pages, 12 figure

    Rollen und Aufgaben der Ergotherapie in der Palliative Care bei erwachsenen Menschen mit Krebserkrankungen in der Schweiz

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    Darstellung des Themas: Die Zahl der Menschen mit Krebserkrankungen in der Schweiz nimmt zu. Sie und ihre Angehörigen benötigen oft über längere Zeit umfassende Behandlung und Betreuung. Deshalb werden Palliative Care Leistungen in den kommenden Jahren stärker gefragt und ein Arbeitsfeld für die Ergotherapie sein. Ziel: Mit dieser Arbeit soll aufgezeigt werden, welche Rollen und Aufgaben die Ergotherapie bei erwachsenen Menschen mit Krebserkrankungen in der Palliative Care in der Schweiz im Zusammenhang mit der Nationalen Strategie Palliative Care 2013 – 2015 übernehmen kann. Methode: Eine systematische Literaturrecherche ergab drei qualitative und zwei Mixed-Method Studies, die zusammengefasst und kritisch beurteilt wurden. Die Studienergebnisse wurden in die Struktur des ergotherapeutischen Modells CMOP-E eingebunden, mit den CanMed Rollen in Verbindung gebracht und mit ergänzender Literatur diskutiert. Relevante Ergebnisse: Die Ergotherapie richtet ihren Fokus auf die Wünsche und Bedürfnisse der Klientinnen und Klienten und ihren Angehörigen. Durch das Ermöglichen von Betätigung oder Umweltanpassungen fördert sie die Teilhabe am sozialen Leben und verbessert die Autonomie und Lebensqualität am Lebensende. Schlussfolgerung: Die Ergotherapie bietet eine nach den Bedürfnissen ausgerichtete Behandlung und leistet deshalb in der Umsetzung der Nationalen Strategie Palliative Care 2013 – 2015 einen wichtigen Beitrag

    Hanle effect in the CN violet system with LTE modeling

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    Weak entangled magnetic fields with mixed polarity occupy the main part of the quiet Sun. The Zeeman effect diagnostics fails to measure such fields because of cancellation in circular polarization. However, the Hanle effect diagnostics, accessible through the second solar spectrum, provides us with a very sensitive tool for studying the distribution of weak magnetic fields on the Sun. Molecular lines are very strong and even dominate in some regions of the second solar spectrum. The CN B2ΣX2ΣB {}^{2} \Sigma - X {}^{2} \Sigma system is one of the richest and most promising systems for molecular diagnostics and well suited for the application of the differential Hanle effect method. The aim is to interpret observations of the CN B2ΣX2ΣB {}^{2} \Sigma - X {}^{2} \Sigma system using the Hanle effect and to obtain an estimation of the magnetic field strength. We assume that the CN molecular layer is situated above the region where the continuum radiation is formed and employ the single-scattering approximation. Together with the Hanle effect theory this provides us with a model that can diagnose turbulent magnetic fields. We have succeeded in fitting modeled CN lines in several regions of the second solar spectrum to observations and obtained a magnetic field strength in the range from 10--30 G in the upper solar photosphere depending on the considered lines.Comment: Accepted for publication in Astronomy and Astrophysic

    Flip-Flops as Observational Signatures of Different Dynamo Modes in Cool Stars

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    Cool, rapidly rotating stars exhibit enhanced magnetic activity with cyclic behavior on various time scales. In particular, the longitude of the dominant activity region switches quasi-periodically by 180∘, which is known as the "flip-flop” phenomenon. In the present paper we introduce a new approach for the interpretation of stellar cycles based on light curve modeling with dipole and quadrupole dynamo modes. We discuss the observational signatures of different combinations of the dynamo modes. The proposed simple model is able to reproduce the basic properties of long-term photometric behavior of active stars and allows us to study different mechanisms resulting in flip-flop
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