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Search Results: 1 - 10 of 4725 matches for " Wolfgang Henke "
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Downregulation of COP9 signalosome subunits differentially affects the CSN complex and target protein stability
Andreas Peth, Christoph Berndt, Wolfgang Henke, Wolfgang Dubiel
BMC Biochemistry , 2007, DOI: 10.1186/1471-2091-8-27
Abstract: Permanent knockdowns of CSN1 and CSN3 led to a reduction of the subunits to approximately 40%, which is accompanied by a proportional decrease of the CSN holocomplex. In contrast, downregulation of CSN5 in HeLa cells reduced the CSN5 protein below 20% without significant effects on the remaining complex. The CRL component Rbx1 was characterized by accelerated proteolysis in siCSN1 and siCSN3 and also in siCSN5 cells, however, with lesser extent. Immunoprecipitated CSN complex from siCSN5 cells was less effective in phosphorylating c-Jun and p27. Accelerated degradation of c-Jun in siCSN5 cells was rescued by overexpression of CSN5 as well as of the deneddylation mutant CSN5D151N. Overexpression of CSN5 cannot rescue c-Jun destabilization in siCSN1.There exists a coordinated downregulation of CSN subunits in the CSN1 and CSN3 knockdowns. The underlying regulatory mechanisms are obscure. CSN5 seems to possess a specific status in HeLa cells. Its reduction is not connected with coordinated downregulation of other subunits. CSN knockdowns confirm that the stabilization of the CRL component Rbx1 is a major CSN function. In addition, downregulation of CSN subunits influences the stability of important cellular regulators such as c-Jun and p27.The COP9 signalosome (CSN) is a conserved protein complex, which controls eukaryotic protein degradation via the ubiquitin (Ub) proteasome system (UPS) [1,2]. In mammals the core complex consists of 8 subunits (CSN1 to CSN8) [3], the exact function of which is not exactly known. CSN5 exhibits a MPN+/JAMM domain [4,5] responsible for metalloprotease activity. As a complex-bound protein CSN5 removes NEDD8, an ubiquitin-like protein, from cullins. This cleavage of an isopeptide bond called deneddylation controls the ubiquitination by cullin-RING Ub ligases (CRLs), a large family of multisubunit E3s [6,7]. Cullin proteins (Cul1 to Cul7) are components of CRLs functioning as scaffolds of the Ub ligase complexes. Cullin neddylation and den
A Grid Concept for Reliable, Flexible and Robust Remote Engineering Laboratories
Karsten Henke
International Journal of Online Engineering (iJOE) , 2012, DOI: 10.3991/ijoe.v8is3.2263
Abstract: Within this paper, we will describe a grid concept to realize a universal remote lab infrastructure as well as different operation modes based on this concept. This new infrastructure consists of three parts: an internal serial remote lab bus, a bus protection unit to interface the remote lab bus and to protect it from misuse and damage as well as a protection unit, which protects the physical systems (the electro-mechanical models in our remote lab) against deliberate damage or accidentally wrong control commands and which offers different access and control mechanisms. The interconnection between the Web-control units and the selected physical system during a remote lab work session (experiment) as well as the user management is done by the lab server, which also handles the webcams. The implemented remote lab infrastructure is based on the iLab architecture of the MIT, which allows to interconnect remote labs and to exchange remote lab experiments among different universities worldwide.
Fields of Applications for Hybrid Online Labs
Karsten Henke
International Journal of Online Engineering (iJOE) , 2013, DOI: 10.3991/ijoe.v9is3.2542
Abstract: Based on a grid concept of an interactive hybrid online laboratory we will describe different fields of applications in different learning scenarios. The infrastructure is based on a universal grid concept which guaranties a reliable, flexible as well as robust usage of this online lab. By using the online lab, students are able to design control algorithms with different specification techniques to control electro-mechanical models in the online lab. Additionally, the reconfigurable rapid prototyping platform of the REAL system can be used to test all the taught topics of a given lectures in the field of digital system design. Finally, a special demonstration platform (a ball in a labyrinth on a balance plate) can be used to give the students a better feeling about the possibilities and limitations of remote control and observation via Internet and to evaluate these technologies critically. The implemented online lab infrastructure is based on the iLab architecture of the MIT, which allows to interconnect online labs and to exchange remote lab experiments among different universities worldwide.
Rapid Prototyping Modules for Remote Engineering Applications
Karsten Henke
International Journal of Online Engineering (iJOE) , 2008,
Abstract: This contribution describes the concept and implementation for an integration of microcontroller and FPGA based Rapid Prototyping modules into a Remote Lab system. This implementation enables a Web-based access to electro-mechanical models. A student uploads a source file implementation to the Remote Lab server in order to test an implementation directly within a hardware environment. The Remote Lab server offers the interfaces to integrate specific project and hardware plug-ins. These plug-ins access a hardware specific software environment to automatically compile and program the resulting firmware. To stimulate this design, the Remote Lab server exchanges digital signals via a serial interface. To allow the student to compare architectures of different designs using the same hardware model, a specific controller (using the Remote Lab interface) can be selected. For this, an IP-based multiplexer provides the control connection between the respective controller and the hardware model. In our contribution we would like to give examples of such a complex design task and how the students can use different tools during several design steps.
Separation of acoustic waves in isentropic flow perturbations
Christian Henke
Physics , 2014, DOI: 10.1016/j.aop.2015.01.030
Abstract: The present contribution investigates the mechanisms of sound generation and propagation in the case of highly-unsteady flows. Based on the linearisation of the isentropic Navier-Stokes equation around a new pathline-averaged base flow, it is demonstrated for the first time that flow perturbations of a non-uniform flow can be split into acoustic and vorticity modes, with the acoustic modes being independent of the vorticity modes. Therefore, we can propose this acoustic perturbation as a general definition of sound. As a consequence of the splitting result, we conclude that the present acoustic perturbation is propagated by the convective wave equation and fulfils Lighthill's acoustic analogy. Moreover, we can define the deviations of the Navier-Stokes equation from the convective wave equation as true sound sources. In contrast to other authors, no assumptions on a slowly varying or irrotational flow are necessary. Using a symmetry argument for the conservation laws, an energy conservation result and a generalisation of the sound intensity are provided.
Minimal Fusion Systems with a Unique Maximal Parabolic
Ellen Henke
Mathematics , 2010,
Abstract: We define minimal fusion systems in a way that every non-solvable fusion system has a section which is minimal. Minimal fusion systems can also be seen as analogs of Thompson's N-groups. In this paper, we consider a minimal fusion system $\mathcal{F}$ on a finite $p$-group $S$ that has a unique maximal $p$-local subsystem containing $N_{\mathcal{F}}(S)$. For an arbitrary prime $p$, we determine the structure of a certain (explicitly described) $p$-local subsystem of $\mathcal{F}$. If $p=2$, this leads to a complete classification of the fusion system $\mathcal{F}$.
Products in Fusion Systems
Ellen Henke
Mathematics , 2012,
Abstract: We revisit the notion of a product of a normal subsystem with a $p$-subgroup as defined by Aschbacher. In particular, we give a previously unknown, more transparent construction.
A characterization of saturated fusion systems over abelian 2-groups
Ellen Henke
Mathematics , 2013,
Abstract: Given a saturated fusion system $\mathcal{F}$ over a $2$-group $S$, we prove that $S$ is abelian provided any element of $S$ is $\mathcal{F}$-conjugate to an element of $Z(S)$. This generalizes a Theorem of Camina--Herzog, leading to a significant simplification of its proof. More importantly, it follows that any $2$-block $B$ of a finite group has abelian defect groups if all $B$-subsections are major. Furthermore, every $2$-block with a symmetric stable center has abelian defect groups.
Products of partial normal subgroups
Ellen Henke
Mathematics , 2015,
Abstract: We show that the product of two partial normal subgroups of a locality (in the sense of Chermak) is again a partial normal subgroup. This generalizes a theorem of Chermak and fits into the context of building a local theory of localities.
Subcentric linking systems
Ellen Henke
Mathematics , 2015,
Abstract: We propose a definition of a linking system which is slightly more general than the one currently in the literature. Whereas the objects of linking systems in the current definition are always quasicentric, the objects of our linking systems only need to satisfy a weaker condition. This leads to the definition of subcentric subgroups of fusion systems. We prove that there is a unique linking system associated to each fusion system whose objects are the subcentric subgroups. Furthermore, the nerve of such a subcentric linking system is homotopy equivalent to the nerve of the centric linking system. The existence of subcentric linking systems seems to be of interest for a classification of fusion systems of characteristic $p$-type. The various results we prove about subcentric subgroups indicate furthermore that the concept is of interest for studying extensions of linking system and fusion systems.
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