102 research outputs found

    Covering and gluing of algebras and differential algebras

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    Extending work of Budzynski and Kondracki, we investigate coverings and gluings of algebras and differential algebras. We describe in detail the gluing of two quantum discs along their classical subspace, giving a C*-algebra isomorphic to a certain Podles sphere, as well as the gluing of U_{\sqrt{q}}(sl_2)-covariant differential calculi on the discs.Comment: latex2e, 27 page

    Connections on locally trivial quantum principal fibre bundles

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    Following the approach of Budzy\'nski and Kondracki, we define covariant differential algebras and connections on locally trivial quantum principal fibre bundles. We also consider covariant derivatives, connection forms and curvatures and explore the relations between these notions. As an example, a U(1) quantum principal bundle over a glued quantum sphere and a connection in this bundle is constructed. This connection may be interpreted as a q-deformed Dirac monopole.Comment: 42 page

    Mixed Valence Europium Nitridosilicate Eu2SiN3

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    The mixed valence europium nitridosilicate Eu2SiN3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH)2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a=542.3(11) pm, b=1061.0(2) pm, c=1162.9(2) pm, Z=8, 767 independent reflections, 37 parameters, R1=0.017, wR2=0.032). Eu2SiN3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN4 tetrahedra running parallel [100] with a maximum stretching factor fs=1.0. The compound is isostructural with Ca2PN3 and Rb2TiO3, and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu2+ and Eu3+, respectively. 151Eu Mössbauer spectroscopy of Eu2SiN3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu2+ and Eu3+ signals over the whole temperature range. The Eu2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 μB/f.u. and a small contribution of Eu3+, in accordance with Eu2+ and Eu3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at TC=24 K. DFT calculations of Eu2SiN3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu2+ and Eu3+

    Lehrkräfteversorgung in der Krise. Wege zur Gewinnung und Begleitung neuer Zielgruppen

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    Ausgehend von dem Mangel an Lehrkräften in gewerblich-technischen Fachrichtungen werden beruflich Qualifizierte als attraktive Zielgruppe für ein entsprechendes Lehramtsstudium betrachtet. Der Beitrag charakterisiert diese Zielgruppe und geht dabei auf deren besondere Bedürfnisse ein. An der TU Dresden können seit dem WS 2019/20 beruflich Qualifizierte im Projekt „Schulassistenz in Qualifizierung“ das Lehramtsstudium mit einer Anstellung im Schuldienst verbinden. Der Beitrag beschreibt das Konzept und geht in seinem Zentrum vor allem auf das bedeutsame Begleitkonzept ein. Ein zentraler Befund ist, dass beruflich Qualifizierte den Anforderungen eines akademischen Studiums gerecht werden, wenn eine entsprechende Begleitung gewährleistet ist. (DIPF/Orig.

    Erfolgreicher Studieneinstieg beruflich Qualifizierter im dualen Studium des technischen Lehramts

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    Der Beitrag informiert über eine dual angelegte Studienoption für das technische Lehramt für nicht-traditionell Studierende. Hintergrund ist, dem Mangel an Lehrkräften an berufsbildenden Schulen durch Aufschließen neuer Zielgruppen zu begegnen und Lehrpersonen auch für den ländlichen Raum zu gewinnen. Der Beitrag fokussiert zum Ersten die Charakterisierung der Studierenden in drei immatrikulierten Durchgängen mit Einblick in Studienwahlmotive und Studieneinstiegsverhalten. Zum Zweiten wird der spezifische Unterstützungsbedarf und das dafür entwickelte Begleitkonzept der Hochschule dargestellt, das einen erfolgreichen Übergang in das Studium sowie Unterstützungs- und Beratungsmöglichkeiten in der Studieneingangsphase gewährleisten soll. Ein Ein- und Ausblick zu Studienverlauf und Studienerfolg beschließen den Beitrag

    Entwicklung eines nationalen Allokationsplans im Rahmen des EU-Emissionshandels

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    The main objective of this project was to support the development of the National Allocation Plan for Germany for the first trading period 2005-07. For this purpose the allocation options had to be analysed and evaluated on the levels of the nation, the sectors, and the installations, considering the legal and political framework as well as the available data bases. In addition, the political process of negotiations in Germany and in Europe had to be accompanied scientifically. Emphasis was placed on the conceptual basics of the allocation planning, on issues of the necessary data bases, the alternatives for the calculation of the macro plan, the general and special allocation rules, and institutional questions. Furthermore, continuous work was required to give support und advice to the Federal Government for the concrete development of the allocation plan and to communicate with stakeholders, in particular with representatives of the German industry

    A Family of Nonlinear Fourth Order Equations of Gradient Flow Type

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    Global existence and long-time behavior of solutions to a family of nonlinear fourth order evolution equations on RdR^d are studied. These equations constitute gradient flows for the perturbed information functionals F[u]=1/(2α)D(uα)2dx+λ/2x2udxF[u] = 1/(2\alpha) \int | D (u^\alpha) |^2 dx + \lambda/2 \int |x|^2 u dx with respect to the L2L^2-Wasserstein metric. The value of α\alpha ranges from α=1/2\alpha=1/2, corresponding to a simplified quantum drift diffusion model, to α=1\alpha=1, corresponding to a thin film type equation.Comment: 33 pages, no figure
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