We identify a general property of concrete domains that is sufficient for proving decidability of DLs equipped with them and GCIs. We show that some useful concrete domains, such as temporal one based on the Allen relations and a spatial one based on the RCC-8 relations, have this property. Then, we present a tableau algorithm for reasoning in DLs equipped with such concrete domains.

Ubiquitinierungen sind dynamische, posttranslationale Proteinmarkierungen, die eine Vielzahl zellulärer Reaktionen hervorrufen. Die strukturell unterschiedlichen Signale werden von einer Ubiquitinierungsmaschinerie, bestehend aus E1-, E2- und E3-Enzymen, aufgebaut. Die Synthese von Polyubiquitin wird durch ubiquitinbindende Domänen (UBD) innerhalb der enzymatischen Kaskade stimuliert. Das E2-Enzym Ubc7 katalysiert zusammen mit dessen Kofaktor Cue1 die Polymerisierung von Ubiquitineinheiten und kennzeichnet Substratproteine mit Lysin 48 (K48)-ver¬knüpf¬ten Ubiquitinketten für den Endoplasmatische Retikulum-assoziierten Proteinabbau (ER-associated protein degradation, ERAD). In dieser Arbeit konnte mittels in vitro rekonstitu¬ierter Ubiquitinierungsreaktionen die Funktionsweise der ubiquitinbindenden CUE-Domäne von Cue1 während der Synthese von Polyubiquitin aufgeklärt werden. Verlängerungs¬reaktionen von Ubiquitinketten konnten durch Fluoreszenzmessungen verfolgt und die CUE-Domäne als Substratrezeptor von Ubc7 beschrieben werden. Anscheinend erhöht die Ubiquitin¬bindung durch Cue1 die lokale Konzentration von Ubc7 an den Ketten und positio¬niert das E2-Enzym effizient für die Übertragung der gebundenen Ubiquiti-neinheit. Die Reaktionen werden durch eine Bindungspräferenz der Cue1-CUE-Domäne für K48-ver¬knüpfte Ubiquitinmoleküle zusätzlich beschleunigt. Es ist bekannt, dass UBDs Ubiquitin¬signale entschlüsseln. Die Charakterisierung der CUE-Domäne beschreibt eine Notwendigkeit der Bindung von Ubiquitin bereits während der Entstehung von Polyubiquitin. Neben den E3-Ubiquitinligasen existieren Deubiquitinasen (DUB), die an der Reifung und dem Abbau von Ubiquitinsignalen beteiligt sind. Die proteasomalen DUBs Ubp6 und Rpn11 zeigen basale Aktivitäten in Isolation, die eingebunden in den 26S-Komplex moduliert werden. Fluoreszenz-basierte Untersuchungen von Kettenabbaureaktionen lassen erste Schlüsse über die Spezifitäten und die Abbaumechanismen der Enzyme zu. / Polyubiquitination is an essential process modulating protein function in eukaryotic cells. Only recently ubiquitin binding activity has emerged as an important factor in ubiquitin chain assembly. Cue1 is a crucial component of yeast endoplasmic reticulum associated protein degradation complexes which recruits and activates the E2 ubiquitin conjugating enzyme Ubc7. Our NMR solution structure reveals an unconventional CUE domain of Cue1 that substantially stimulates ubiquitin chain elongation by Ubc7.Results from NMR analysis combined with interaction studies and in vitro ubiquitination reactions imply that binding of CUE to a ubiquitin moiety adjacent to the acceptor ubiquitin is a prerequisite for rapid chain elongation. By this mode of action, the CUE domain counteracts the inability of associated Ubc7, to progressively elongate ubiquitin chains. Elongation of K48-linked ubiquitin chains is additionally accelerated since the CUE domain preferentially binds chains of K48-linkage. Our data support a model, where dynamic binding of ubiquitin chains assist to position Ubc7 for rapid elongation of K48-linked chains. Thus, the CUE domain acts as acceleration factor of elongation. Our study provides detailed mechanistic insight into how a ubiquitin binding domain governs polyubiquitin chain formation.

In der Optogenetik werden genetisch codierbare Photorezeptorproteine in Zellen eingebracht, um spezifische Parameter durch Licht zu kontrollieren. Um den sekundären Botenstoff zyklisches Adenosinmonophosphat (cAMP) zugänglich zu machen, haben wir vier neu identifizierte photoaktivierte Adenylatzyklasen untersucht. Die vier Gene stammen aus einem Sulfid oxidierenden Bakterium Beggiatoa und aus einem Amoeboflagellaten Naegleria gruberi. Sie codieren für 350 bis 489 Aminosäuren lange Proteine und enthalten eine Blaulicht wahrnehmende BLUF- (blue light sensors using FAD) und eine Adenylatzyklasedomäne. Zellbasierte Funktionstests in E. coli, Xenopus Oozyten und CHO Zellen sowie die Bestimmung der Adenylatzyklase-Aktivität in vitro zeigen, dass alle vier PACs lichtaktiviert arbeiten. Dabei besitzt die bakterielle PAC (bPAC) das größte Potenzial für eine optogenetische Anwendung, da sie eine hohe Lichtaktivität und ein große Licht-zu-Dunkel-Aktivitätsverhältnis besitzt. Um den Vorteil bPACs gegenüber PACalpha aus Euglena zu demonstrieren, verglichen wir beide PACS in Xenopus Oozyten, in Ratten Neuronen und in Drosophila Fliegen. Gegenüber PACalpha besitzt bPAC eine geringere Aktivität im Dunkeln, eine höhere Lichtsensitivität und einen breiteren dynamischen Bereiche und ist damit für viele Anwendungen die bevorzugte PAC. In einem analytischen Ansatz untersuchten wir die Bedeutung der BLUF-Domänen für die Regulation von bPAC. Nach Entfernen der BLUF-Domänen verblieb nur die inaktive Zyklase. Mutationen innerhalb der BLUF-Domäne, die die Photochemie oder die Signaltransduktion beeinflussten, führten zur Ausbildung eines partiell aktiven Rezeptorgrundzustandes. Dies verdeutlicht die Bedeutung eines intakten Wasserstoffbrückennetzwerkes für die funktionelle Regulation von bPAC. Als Ergenbis einer anwendungsorientierten Optimierung wurden eine bPAC Variante mit reduzierter Dunkelaktivität sowie eine Variante erhalten, die ein stabiles, neutrales Flavinradikal ausbildet. / Optogenetics represents the use of genetically encoded photoreceptor proteins to control specific parameters of cells by light. To particularly access optic control of the second messenger cyclic adenosine monophosphate (cAMP) we tested the suitability of four newly identified photoactivated adenylyl cyclases (PAC). Their genes originate from a soil bacterium Beggiatoa sp. and from an amoeboflagellate Naegleria gruberi. They code for 350 to 489 aa small proteins consisting of one blue light sensing BLUF (blue light sensors using FAD) and one adenylyl cyclase domain. Cell based functional assays in E. coli, Xenopus oocytes and CHO cells as well as in vitro analysis of recombinant protein reveal that all four PACs are light activated adenylyl cyclases. Moreover the bacterial PAC (bPAC) has the highest potential for an optogenetic application due to its high activity in light and low activity in the dark. To demonstrate the advantage of bPAC over the established Euglena PACalpha we compared both proteins in Xenopus oocytes, rat neurons and Drosophila fruit flies. It appears that bPAC features a lower activity in the dark, a higher light sensitivity and a broader dynamic range. Therefore bPAC is the superior optogenetic tool for many applications. In an analytical approach we investigated the impact of the BLUF domains on regulation of the cyclase. Removal of the BLUF domains left the bPAC cyclase in an inactive state. Mutating BLUF residues, which are involved either in photochemistry or signal transduction, resulted in a partially active dark state and reduced light activation of bPAC. Thus the integrity of the BLUF domain hydrogen bond network is essential for functional regulation of bPAC. As a result from application oriented optimization a bPAC variant with reduced dark activity as well as a variant that forms a stable neutral flavin radical was obtained.

No description available.

Magnetic shape memory (MSM) materials are a new class of smart materials which exhibit shape deformation under the influence of an external magnetic field. They are interesting for various types of applications, including actuators, displacement/force sensors, and motion dampers. Due to the huge strain and the magnetic field-driven nature, MSM materials show definite advantages over other smart materials, e.g. conventional thermal shape memory materials, in terms of displacement and speed. The principle behind the magnetic field induced strain (MFIS) is the strong coupling between magnetization and lattice structure. The investigation of both static and dynamic magnetic domain structures in MSM materials is a key step in optimizing the properties for future possible devices. In this work, optical polarization microscopy is applied to investigate the twin boundary and magnetic domain wall motion in bulk NiMnGa single crystals. Surface magnetic domain patterns on adjacent sides of bulk crystals are revealed for the first time providing comprehensive information about the domain arrangement inside the bulk and at the twin boundary. The tilting of the easy axis with respect to the sample surface determines the preferable domain size and leads to spike domain formation on the surface. Out-of-plane surface domains extend into the bulk within a single variant, while a twin boundary mirrors the domain pattern from adjacent variants. Furthermore, magnetic domain evolution during twin boundary motion is observed. The partial absence of domain wall motion throughout the process contradicts currently proposed models. The magnetic state alternates along a moving twin boundary. With the abrupt nucleation of the second variant this leads to the formation of sections of magnetically highly charged head-on domain structures at the twin boundaries. On the other hand, a dynamic actuation experimental setup, which is capable to provide high magnetic fields in a wide range of frequency, was developed in the course of this study. The observation of reversible twin boundary motion up to 600 Hz exhibits the dependence of strain, hysteresis, and twin boundary velocity on the actuation speed. MFIS increases with frequency, while the onset field is similar in all observed cases. Twin boundary mobility enhancement by fast twin boundary motion is proposed to explain the increase in MFIS. The twin boundary velocity is shown to be inversely proportional to the twin boundary density. No limit of twin boundary velocity is observed in the investigated frequency range.

From the Motivation: „Description Logics (DLs) are a family of formalisms well-suited for the representation of and reasoning about knowledge. Whereas most Description Logics represent only static aspects of the application domain, recent research resulted in the exploration of various Description Logics that allow to, additionally, represent temporal information, see [4] for an overview. The approaches to integrate time differ in at least two important aspects: First, the basic temporal entity may be a time point or a time interval. Second, the temporal structure may be part of the semantics (yielding a multi-dimensional semantics) or it may be integrated as a so-called concrete domain. Examples for multi-dimensional point-based logics can be find in, e.g., [21;29], while multi-dimensional interval-based logics are used in, e.g., [23;2]. The concrete domain approach needs some more explanation. Concrete domains have been proposed by Baader and Hanschke as an extension of Description Logics that allows reasoning about 'concrete qualities' of the entities of the application domain such as sizes, length, or weights of real-worlds objects [5]. Description Logics with concrete domains do usually not use a fixed concrete domain; instead the concrete domain can be thought of as a parameter to the logic. As was first described in [16], if a 'temporal' concrete domain is employed, then concrete domains may be point-based, interval-based, or both. ...”

We show how to combine the standard tableau system for the basic description logic ALC and Wolper´s tableau calculus for propositional temporal logic PTL (with the temporal operators ‘next-time’ and ‘until’) in order to design a terminating sound and complete tableau-based satisfiability-checking algorithm for the temporal description logic PTL ALC of [19] interpreted in models with constant domains. We use the method of quasimodels [17, 15] to represent models with infinite domains, and the technique of minimal types [11] to maintain these domains constant. The combination is flexible and can be extended to more expressive description logics or even do decidable fragments of first-order temporal logics.

No description available.

No description available.

No description available.