464 research outputs found

    Sociomoral atmosphere and prosocial and democratic value orientations in enterprises with different levels of structurally anchored participation

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    This study examines effects of structurally anchored organisational democracy on perceived sociomoral atmosphere and on employees' prosocial, democratic behavioural orientations. Data result from the ODEM research project. Beside a description of the concept of sociomoral atmosphere, within this project, 30 small and medium sized enterprises from Austria, North Italy, South Germany, and Liechtenstein (542 participants) were surveyed with questionnaires, interviews, and document analyses. Based on organisational science criteria, several types of enterprises were derived and pooled into three groups of structurally anchored organisational democracy (no, medium, and high democracy). Multivariate group analyses show significant differences between those groups in parts of their prosocial and democratic behavioural orientations and in their sociomoral atmosphere.Die vorliegende Arbeit fokussiert die Effekte strukturell verankerter organisationaler Demokratie auf die wahrgenommene soziomoralische Atmosphäre der Beschäftigten und auf deren soziale und demokratieförderliche Handlungsbereitschaften. Vorgestellt werden neben einem Konzeptvorschlag zur soziomoralischen Atmosphäre empirische Ergebnisse aus dem Forschungsprojekt ODEM, in welchem 30 KMUs aus dem deutschsprachigen Raum (542 Probanden) mittels standardisiertem Fragebogen, Experteninterviews und Dokumentenanalysen untersucht wurden. Zur Auswertung wurden - nach organisationswissenschaftlichen Kriterien gebildete - Unternehmenstypen theoriegeleitet zu drei Gruppen struktureller organisationaler Demokratie (keine, mittlere und hohe Demokratieausprägung) zusammengefasst. Multivariate Gruppenvergleiche zeigen signifikante Unterschiede zwischen diesen Gruppen hinsichtlich der soziomoralischen Atmosphäre sowie in Teilen der prosozialen und demokratischen Handlungsbereitschaften

    CEP-stable Tunable THz-Emission Originating from Laser-Waveform-Controlled Sub-Cycle Plasma-Electron Bursts

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    We study THz-emission from a plasma driven by an incommensurate-frequency two-colour laser field. A semi-classical transient electron current model is derived from a fully quantum-mechanical description of the emission process in terms of sub-cycle field-ionization followed by continuum-continuum electron transitions. For the experiment, a CEP-locked laser and a near-degenerate optical parametric amplifier are used to produce two-colour pulses that consist of the fundamental and its near-half frequency. By choosing two incommensurate frequencies, the frequency of the CEP-stable THz-emission can be continuously tuned into the mid-IR range. This measured frequency dependence of the THz-emission is found to be consistent with the semi-classical transient electron current model, similar to the Brunel mechanism of harmonic generation

    Bound-to-bound and bound-to-continuum optical transitions in combined quantum dot - superlattice systems

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    By combining band gap engineering with the self-organized growth of quantum dots, we present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot based photodetectors. Embedding the self organized InAs quantum dots into an AlAs/GaAs superlattice enables us to tune the optical transition energy by changing the superlattice period as well as by changing the growth conditions of the dots. Using a one band envelope function framework we are able, in a fully three dimensional calculation, to predict the photocurrent spectra of these devices as well as their polarization properties. The calculations further predict a strong impact of the dots on the superlattices minibands. The impact of vertical dot alignment or misalignment on the absorption properties of this dot/superlattice structure is investigated. The observed photocurrent spectra of vertically coupled quantum dot stacks show very good agreement with the calculations.In these experiments, vertically coupled quantum dot stacks show the best performance in the desired photodetector application.Comment: 8 pages, 10 figures, submitted to PR

    Electrically Switchable Photonic Molecule Laser

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    We have studied the coherent intercavity coupling of the evanescent fields of the whispering gallery modes of two terahertz quantum-cascade lasers implemented as microdisk cavities. The electrically pumped single-mode operating microcavities allow to electrically control the coherent mode coupling for proximity distances of the cavities up to 30-40 \mu\m. The optical emission of the strongest coupled photonic molecule can be perfectly switched by the electrical modulation of only one of the coupled microdisks. The threshold characteristics of the strongest coupled photonic molecule demonstrates the linear dependence of the gain of a quantum-cascade laser on the applied electric field.Comment: 4 pages, 4 figure

    Intraband transitions in quantum dot-superlattice heterostructures

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    8 pages, 10 figuresWe present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot-based photodetectors by combining band gap engineering with the self-organized growth of quantum dots. Embedding the self-organized InAs quantum dots into an AlAs/GaAs superlattice enables us to tune the optical transition energy by changing the superlattice period as well as by changing the growth conditions of the dots. Using a one-band envelope function framework, we are able, in a three-dimensional calculation, to predict the absorption spectra of these devices as well as their polarization properties. These calculations further predict a strong impact of the dots on the superlattice minibands. By comparing aligned, periodic dot stacks with nonperiodic dot arrangements within the superlattice, we can experimentally confirm this prediction

    Linear optical absorption spectra of mesoscopic structures in intense THz fields: free particle properties

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    We theoretically study the effect of THz radiation on the linear optical absorption spectra of semiconductor structures. A general theoretical framework, based on non-equilibrium Green functions, is formulated, and applied to the calculation of linear optical absorption spectrum for several non-equilibrium mesoscopic structures. We show that a blue-shift occurs and sidebands appear in bulk-like structures, i.e., the dynamical Franz-Keldysh effect [A.-P. Jauho and K. Johnsen, Phys. Rev. Lett. 76, 4576 (1996)]. An analytic calculation leads to the prediction that in the case of superlattices distinct stable steps appear in the absorption spectrum when conditions for dynamical localization are met.Comment: 13 Pages, RevTex using epsf to include 8 ps figures. Submitted to Phys. Rev. B (3 April 97

    Intersubband gain in a Bloch oscillator and Quantum cascade laser

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    The link between the inversion gain of quantum cascade structures and the Bloch gain in periodic superlattices is presented. The proposed theoretical model based on the density matrix formalism is able to treat the gain mechanism of the Bloch oscillator and Quantum cascade laser on the same footing by taking into account in-plane momentum relaxation. The model predicts a dispersive contribution in addition to the (usual) population-inversion-dependent intersubband gain in quantum cascade structures and - in the absence of inversion - provides the quantum mechanical description for the dispersive gain in superlattices. It corroborates the predictions of the semi-classical miniband picture, according to which gain is predicted for photon energies lower than the Bloch oscillation frequency, whereas net absorption is expected at higher photon energies, as a description which is valid in the high-temperature limit. A red-shift of the amplified emission with respect to the resonant transition energy results from the dispersive gain contribution in any intersubband transition, for which the population inversion is small.Comment: 10 pages, 6 figure

    Subjektive Repräsentation der Zusammenhänge zwischen Organisationsstruktur, soziomoralischer Atmosphäre und prosozialem Arbeitshandeln in demokratischen Unternehmen – eine Kreuzvalidierung

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    Theoretischer Hintergrund und Fragestellung Bei der Erforschung der individuellen moralischen Urteilskompetenz wurde zunehmend die Frage verfolgt, more about welche organisationalen Merkmale, buy Interaktionspraktiken und Interventionen in Institutionen sich fördernd bzw. hemmend auf die Genese von Kompetenzen und Handlungsorientierungen, die ethisch angemessenem Handeln zugrunde liegen, auswirken (z.B. Lempert, 2009; Oser & Althof, 2001; Power, Higgins, & Kohlberg, 1989

    Detection of Splenic Tissue Using Tc-99m-Labelled Denatured Red Blood Cells Scintigraphy-A Quantitative Single Center Analysis

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    Background: Red blood cells (RBC) scintigraphy can be used not only for detection of bleeding sites, but also of spleen tissue. However, there is no established quantitative readout. Therefore, we investigated uptake in suspected splenic lesions in direct quantitative correlation to sites of physiologic uptake in order to objectify the readout. Methods: 20 patients with Tc-99m-labelled RBC scintigraphy and SPECT/low-dose CT for assessment of suspected splenic tissue were included. Lesions were rated as vital splenic or non-splenic tissue, and uptake and physiologic uptake of bone marrow, pancreas, and spleen were then quantified using a volume-of-interest based approach. Hepatic uptake served as a reference. Results: The median uptake ratio was significantly higher in splenic (2.82 (range, 0.58-24.10), n = 47) compared to other lesions (0.49 (0.01-0.83), n = 7), p < 0.001, and 5 lesions were newly discovered. The median pancreatic uptake was 0.09 (range 0.03-0.67), bone marrow 0.17 (0.03-0.45), and orthotopic spleen 14.45 (3.04-29.82). Compared to orthotopic spleens, the pancreas showed lowest uptake (0.09 vs. 14.45, p = 0.004). Based on pancreatic uptake we defined a cutoff (0.75) to distinguish splenic from other tissues. Conclusion: As the uptake in extra-splenic regions is invariably low compared to splenules, it can be used as comparator for evaluating suspected splenic tissues
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