Monopoly

Mathematische Semesterberichte - Die Spielidee des Monopoly-Spiels ist mehr als 100 Jahre alt. Ein Grund für den beständigen Erfolg ist die Anpassungsfähigkeit der Spielidee....     

Profiles and Quantization of the Blow Up Mass for Critical Nonlinear Schrödinger Equation

We consider finite time blow up solutions to the critical nonlinear Schrödinger equation For a suitable class of initial data in the energy space H¹, we prove that the solution splits in two parts: the first part corresponds to the singular part and accumulates a quantized amount of L² mass at the blow up point, the second part corresponds to the regular part and has a strong L² limit at blow up time.Part of this work has been supported by grant DMS-0111298.     

A FeIII/Oxo Cubane Contained in an Octanuclear Complex of T Symmetry That Is Stable Over Five Oxidation States

Encapsulated in a protective [{Fe(pz)₃}₄] outer layer, which provides the complex with structural stability, the octanuclear complex [Fe₈(μ⁴-O)₄(μ-pz)₁₂Cl₄] contains a Fe₄O₄ core (see drawing) that withstands four consecutive reversible one-electron reductions. Iron–oxygen clusters are shown to possess redox properties which rival those of their better studied iron–sulfur analogues. pz=pyrazolate anion.     

Unorthodox intrasubunit interactions in the cellulosome ofClostridium thermocellum

Clostridium thermocellum, an anaerobic thermophilic cellulolytic bacterium, produces an extremely cohesive, very high-molecular-mass multicellulase-containing complex termed thecellulosome. One of its components, the S1 subunit, is a nonenzymatic, 210 kDa glycopolypeptide. Upon preconditioning of the intact cellulosome with lowionic-strength or low-pH solutions, the S1 subunit separates in hot sodium dodecyl sulfate (SDS) solutions into a series of defined lowermolecular-mass subcomponents. Under the same conditions, the purified S1 subunit demonstrated the same behavior. Higher levels of glycosylation associated with the larger S1 subcomponents. The data support alterations in the conformational state of the S1 structure that lead to its disintegration induced by combined treatments with SDS and heating. Evidence is provided that this phenomenon may reflect a physiological response of the cellulosome, since similar alterations in S1 appear to accompany its binding to cellulose.     

DNS of premixed turbulent V-flame: coupling spectral and finite difference methods

To allow for a reliable examination of the interaction between velocity fluctuations, acoustics and combustion, a novel numerical procedure is discussed in which a spectral solution of the Navier–Stokes equations is directly associated to a high-order finite difference fully compressible DNS solver (sixth order PADE). Using this combination of high-order solvers with accurate boundary conditions, simulations have been performed where a turbulent premixed V-shape flame develops in grid turbulence. In the light of the DNS results, a sub-model for premixed turbulent combustion is analyzed. To cite this article: R. Hauguel et al., C. R. Mecanique 333 (2005).     

Notions and relations for RKA-secure permutation and function families

The theory of designing block ciphers is mature, having seen significant progress since the early 1990s for over two decades, especially during the AES development effort. Nevertheless, interesting directions exist, in particular in the study of the provable security of block ciphers along similar veins as public-key primitives, i.e. the notion of pseudorandomness (PRP) and indistinguishability (IND). Furthermore, recent cryptanalytic progress has shown that block ciphers well designed against known cryptanalysis techniques including related-key attacks (RKA) may turn out to be less secure against RKA than expected. The notion of provable security of block ciphers against RKA was initiated by Bellare and Kohno, and subsequently treated by Lucks. Concrete block cipher constructions were proposed therein with provable security guarantees. In this paper, we are interested in the security notions for RKA-secure block ciphers. In the first part of the paper, we show that secure tweakable permutation families in the sense of strong pseudorandom permutation (SPRP) can be transformed into secure permutation families in the sense of SPRP against some classes of RKA (SPRP–RKA). This fact allows us to construct a secure SPRP–RKA cipher which is faster than the Bellare–Kohno PRP–RKA cipher. We also show that function families of a certain form secure in the sense of a pseudorandom function (PRF) can be transformed into secure permutation families in the sense of PRP against some classes of RKA (PRP–RKA). We can exploit it to get various constructions secure against some classes of RKA from known MAC algorithms. Furthermore, we discuss how the key recovery (KR) security of the Bellare–Kohno PRP–RKA, the Lucks PRP–RKA and our SPRP–RKA ciphers relates to existing types of attacks on block ciphers like meet-in-the-middle and slide attacks. In the second part of the paper, we define other security notions for RKA-secure block ciphers, namely in the sense of indistinguishability (IND) and non-malleability, and show the relations between these security notions. In particular, we show that secure tweakable permutation families in the sense of IND (resp. non-malleability) can be transformed into RKA-secure permutation families in the sense of IND (resp. non-malleability).     

Quantitative simulation of photoacoustic signals using finite element modelling software

This paper aims to demonstrate the quantitative simulation of photoacoustic signals using finite element modelling software. The software Comsol Multiphysics is used to calculate the response of a differential Helmholtz resonator cell previously modeled using an electrical analogy. Quality factors and resonance frequencies are compared with experimental ones. Moreover, for the first time, the absorption coefficient of the gas sample and the laser intensity are also used to quantitatively predict photoacoustic signal that can be obtained in such a configuration.     

Kolloidchemie des Bindegewebes

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