Lower bound for the ground state energy of the no-pair Hamiltonian

A lower bound for the ground state energy of a one particle relativistic Hamiltonian - sometimes called no-pair operator - is provided.Comment: 5 pages, 1 figure, 1 table, Latex2e (amssymb,amsmath,graphicx

Exponential localization of hydrogen-like atoms in relativistic quantum electrodynamics

We consider two different models of a hydrogenic atom in a quantized electromagnetic field that treat the electron relativistically. The first one is a no-pair model in the free picture, the second one is given by the semi-relativistic Pauli-Fierz Hamiltonian. We prove that the no-pair operator is semi-bounded below and that its spectral subspaces corresponding to energies below the ionization threshold are exponentially localized. Both results hold true, for arbitrary values of the fine-structure constant, $e^2$, and the ultra-violet cut-off, $\Lambda$, and for all nuclear charges less than the critical charge without radiation field, $Z_c=e^{-2}2/(2/\pi+\pi/2)$. We obtain similar results for the semi-relativistic Pauli-Fierz operator, again for all values of $e^2$ and $\Lambda$ and for nuclear charges less than $e^{-2}2/\pi$.Comment: 37 page

Generic Weakest Precondition Semantics from Monads Enriched with Order

Abstract. We devise a generic framework where a weakest precondi-tion semantics, in the form of indexed posets, is derived from a monad whose Kleisli category is enriched by posets. It is inspired by Jacobs’ recent identification of a categorical structure that is common in various predicate transformers, but adds generality in the following aspects: 1) different notions of modality (such as “may ” vs. “must”) are captured by Eilenberg-Moore algebras; 2) nested branching—like in games and in probabilistic systems with nondeterministic environments—is modularly modeled by a monad on the Eilenberg-Moore category of another.

Weiterentwickelte Modellansaetze chemischer und physikalischer Effekte im Grubengebaeude eines Endlagers im Salinar

The study examines the radioactivity transport within an underground mine structure by means of a simplified structural model. This approach yields relative results on the significance of sorption processes, but will not deliver absolute results for safety assessments. The containment of nuclides within the close-in area is simulated by a linear approach describing sorption according to the K_d-concept, with the K_d values being varied for determination of the effects of sorption. The report firstly explains the underground mine structure considered and the modelling assumptions and effects of the release and transport calculations, as well as, in great detail, the modelling of sorption processes in the underground structure. Then the modelling computations performed and the movement of brines are discussed, brines being salt solutions entering the underground structure from the outside of the mine or flowing in from the host rock. Further aspects examined are the effects of sorption processes along a snicket gate within the structure, or within the emplacement area. The two variants are comparatively analysed, and the concluding chapter shows the effects of sorption by a model combining the two variants. (orig./DG)In der Studie wird der Aktivitaetstransport im Grubengebaeude anhand einer vereinfachten Grubengebaeudestruktur untersucht. Hierdurch sind relative Aussagen zur Bedeutung der Sorption, jedoch keine Absolutaussagen zur Bewertung der Sicherheit des Endlagers moeglich. Die Rueckhaltung der Nuklide im Nahbereich wird mit einem linearen Sorptionsansatz nach dem K_d-Konzept realisiert, wobei die K_d-Werte zur Feststellung des Einflusses der Sorption variiert werden. Zunaechst werden die betrachtete Grubengebaeudestruktur und die Modellannahmen und Effekte der Freisetzungs- und Ausbreitungsrechnungen sowie im Detail die Modellierung der Sorption im Grubengebaeude erlaeutert. Danach wird auf die durchgefuehrten Modellrechnungen und auf die Laugenbewegung eingegangen. Mit Lauge wird die von aussen oder aus dem Wirtsgestein in das Grubengebaeude zugeflossene Salzloesung bezeichnet. Weiterhin werden die Auswirkungen der Sorption innerhalb einer Verbindungsstrecke im Grubengebaeude und die Sorption innerhalb des Einlagerungsbereichs behandelt sowie die beiden Varianten verglichen und abschliessend erfolgt die Darstellung des Sorptionseinflusses fuer die Kombination beider Varianten. (orig./DG)SIGLEAvailable from TIB Hannover: RN 6050(123) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman