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The occurrence of self-avoiding closed paths (cycles) in networks is studied under varying rules of wiring. As a main result, we find that the dependence between network size and typical cycle length is algebraic, (h) proportional to Nalpha, with distinct values of for different wiring rules. The Barabasi-Albert model has alpha=1. Different preferential and nonpreferential attachment rules and the growing Internet graph yield alpha<1. Computation of the statistics of cycles at arbitrary length is made possible by the introduction of an efficient sampling algorithm.

Local minima and the saddle points separating them in the energy landscape are known to dominate the dynamics of biopolymer folding. Here we introduce a notion of a “folding funnel” that is concisely defined in terms of energy minima and saddle points, while at the same time conforming to a notion of a “folding funnel” as it is discussed in the protein folding literature.

In dieser Arbeit soll der Messeffekt einer BeO-Sonde korrigiert werden. Dieser wird durch Radiolumineszenz im Sondenmaterial ausgelöst. Abhängig vom Stoßbremsvermögen der auftretenden Teilchen treten dabei Sättigungseffekte der Sonde auf, welche zu einer Dosisunterschätzung führen. Das Lumineszenzspektrum der Sonde zeigt Maxima bei zwei verschiedenen Wellenlängen. Diese werden bei variabler Geschwindigkeit der auftretenden Teilchenstrahlung untersucht. Durch Kombination des Messaufbaus mit einem geeigneten Strahlteiler kann das Spektrum am Wendepunkt in zwei Anteile zerlegt und das Verhältnis der Zählraten untersucht werden. Es zeigt sich, dass sich dieses Verhältnis mit der Geschwindigkeit der auftretenden Teilchen ändert. Da es auch mit deren Bremsvermögen korreliert, wird es genutzt um eine Korrekturfunktion für den Messeffekt der BeO-Sonde aufzustellen.

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Quantum information technologies require networks of interacting defect bits. Color centers, especially the nitrogen vacancy (NV-) center in diamond, represent one promising avenue, toward the realisation of such devices. The most successful technique for creating NV- in diamond is ion implantation followed by annealing. Previous experiments have shown that shallow nitrogen implantation (<10 keV) results in NV- centers with a yield of 0.01%–0.1%. We investigate the influence of channeling effects during shallow implantation and statistical diffusion of vacancies using molecular dynamics and Monte Carlo simulation techniques. Energy barriers for the diffusion process were calculated using density functional theory. Our simulations show that 25% of the implanted nitrogens form a NV center, which is in good agreement with our experimental findings.

Usually one distinguishes partial and complete wetting of surfaces or interfaces. In case of partial wetting contact angle θ > 0 and the liquid droplet is surrounded by “dry” surface or interface. In the majority of cases the direct transition occurs from partial wetting into complete wetting, for example by increasing temperature or decreasing pressure. However, in some cases the state of pseudopartial wetting occurs between partial and complete wetting. In this case the contact angle θ > 0, the liquid droplet does not spread over the substrate, but the thin (few nm) precursor film exists around the droplet and separates substrate and gas. Such precursor film is very similar for the liquid “pancake” in case of complete wetting and deficit of the liquid phase. The pseudopartial wetting has been observed before only for liquid/liquid mixtures (alcanes/water solution of salt or glucose) or Pb and Bi on the Cu surface. We observed the pseudopartial wetting of Al/Al grain boundaries (GBs) by solid Zn in the Al – 10 wt.% Zn ultra-fine grained polycrystals. The solid Zn partially wets Al/Al GBs (with non-zero contact angle). Nevertheless, the Al/Al GBs contain the 2 nm thin uniform Zn-rich layer connected with Zn grains. Such thin layers are the reason of high ductility of ultra-fine grained Al–Zn alloys at room temperature. This phenomenon opens the way for development of novel light-weight alloys. The pseudopartieal GB wetting by a liquid phase exists also in the WC–Co hard alloys. The pseudopartieal GB wetting by various liquid and solid phases also controls the properties of Nd–Fe–B-based hard magnetic alloys.

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No description available.

We present the generalized method of separation of variables (GMSV) to solve boundary value problems for the stationary diffusion equation in three-dimensional canonical domains (e.g., parallelepipeds, cylinders, spheres, spheroids, ..., and also their combinations).