Structurally and functionally unique complexins at retinal ribbon synapses

Ribbon synapses in retinal sensory neurons maintain large pools of readily releasable synaptic vesicles. This allows them to release several hundreds of vesicles per second at every presynaptic release site. The molecular components that cause this high transmitter release efficiency of ribbon synapses are unknown. In the present study, we identified and characterized two novel vertebrate complexins (CPXs), CPXs III and IV, that are the only CPX isoforms present in retinal ribbon synapses. CPXs III and IV are COOH-terminally farnesylated, and, like CPXs I and II, bind to SNAP receptor complexes. CPXs III and IV can functionally replace CPXs I and II, and their COOH-terminal farnesylation regulates their synaptic targeting and modulatory function in transmitter release. The novel CPXs III and IV may contribute to the unique release efficacy of retinal sensory neurons

Herstellungs-optimierte Struktur-Montage (HERMO) - Schlussbericht

Im Rahmen des Projekts HERMO wurde innerhalb des KOSMO-Verbundes das Friction Stir Welding (FSW) für die Herstellung von Tailored Welded Blanks sowie zur Ermöglichung splicefreier Faser Metall Laminate (FML) durch FSW dünner Aluminiumbleche untersucht. Hierbei wurden auch wesentliche Aspekte beleuchtet, die für den Einsatz des FSW in der industriellen Praxis relevant sind, wie z.B. Robustheit des FSW-Prozesses hinsichtlich Parametervariation, die Möglichkeit der Ultraschallprüfung von FSW-TWB sowie der Verzug von FSW-Verbindungen wie auch FML. Zusammengefasst konnten basierend auf den Arbeiten Empfehlungen für das TWB-Design sowie geeignete FSW-Parameter (hinsichtlich Fehlerfreiheit und Festigkeit der FSW-Verbindung) für die untersuchten Legierungen 6013 sowie Ko8242 gegeben werden. Auch konnte gezeigt werden, dass der Aspekt des Verzugs beim FSW in erster Näherung sinnvoll über transiente thermo-mechanische FE-Simulationen qualitativ richtig abgebildet werden kann. Erste Untersuchungen zur Ermüdungsrissausbreitung in der FSW-Naht sowie zur Restfestigkeit bei vorhandenem Riss zeigen, dass die bereitgestellten FSW-Parameter grundsätzlich geeignet scheinen, um auch Quer- oder Längsnähte in metallischen Rumpfstrukturen zu erzeugen

Active zone proteins are dynamically associated with synaptic ribbons in rat pinealocytes

Synaptic ribbons (SRs) are prominent organelles that are abundant in the ribbon synapses of sensory neurons where they represent a specialization of the cytomatrix at the active zone (CAZ). SRs occur not only in neurons, but also in neuroendocrine pinealocytes where their function is still obscure. In this study, we report that pinealocyte SRs are associated with CAZ proteins such as Bassoon, Piccolo, CtBP1, Munc13–1, and the motorprotein KIF3A and, therefore, consist of a protein complex that resembles the ribbon complex of retinal and other sensory ribbon synapses. The pinealocyte ribbon complex is biochemically dynamic. Its protein composition changes in favor of Bassoon, Piccolo, and Munc13–1 at night and in favor of KIF3A during the day, whereas CtBP1 is equally present during the night and day. The diurnal dynamics of the ribbon complex persist under constant darkness and decrease after stimulus deprivation of the pineal gland by constant light. Our findings indicate that neuroendocrine pinealocytes possess a protein complex that resembles the CAZ of ribbon synapses in sensory organs and whose dynamics are under circadian regulation

Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.Comment: 19 pages, 3 figures. V2: Few typos corrected and references added. Matches published version JCAP 02 (2016) 03

Concerted action of zinc and ProSAP/Shank in synaptogenesis and synapse maturation

ProSAP/Shank are scaffolding proteins that localize to the postsynaptic density (PSD). This study shows that Zn2+ ions directly regulate the localization and recruitment of Shank/ProSAP1/2 to PSDs to facilitate synapse formation and maturation

Influence of R-Ratio on Fatigue of Aluminum Bonding Wires

Bonding wires made of aluminum are the most used materials for the transmission of electrical signals in power electronic devices. During operation, different cyclic mechanical and thermal stresses can lead to fatigue loads and a failure of the bonding wires. A prediction or prevention of the wire failure is not yet possible by design for all cases. The following work presents meaningful fatigue tests in small wire dimensions and investigates the influence of the R-ratio on the lifetime of two different aluminum wires with a diameter of 300 µm each. The experiments show very reproducible fatigue results with ductile failure behavior. The endurable stress amplitude decreases linearly with an increasing stress ratio, which can be displayed by a Smith diagram, even though the applied maximum stresses exceed the initial yield stresses determined by tensile tests. A scaling of the fatigue results by the tensile strength indicates that the fatigue level is significantly influenced by the strength of the material. Due to the very consistent findings, the development of a generalized fatigue model for predicting the lifetime of bonding wires with an arbitrary loading situation seems to be possible and will be further investigated

Adaption of a material model and development of a stochastic failure criterion for ceramic matrix composite structures

Ceramic matrix composites (CMCs) show high thermal resistance combined with damage tolerance and non-brittle failure. Therefore, they are suitable for mechanically loaded components at high temperatures. For dimensioning of components, an adaption of existing simulation and calculation methods for CMC materials is required. The material investigated in this work is a wound oxide CMC with a defined fiber orientation and a highly porous matrix. Due to manufacturing conditions, randomly distributed macroscopic pores are present in the composite. Since failure is initiated by these pores, a statistical investigation of strength is performed based on the weakest link theory. Several series of tensile tests were performed to reveal the relation between stress and strain and obtain their ultimate values. The application of two statistical criteria showed that fracture strains are well represented by Weibull distributions. The tensile tests were compared with results of finite element simulations, using the simulation software ANSYS. An anisotropic Weibull criterion was set up and adapted to the results of the tensile tests. Hereby, the anisotropic nonlinear deformation behavior as well as the scatter of failure strain could be reproduced by numerical simulations. The adapted material model and failure criterion were validated by further experiments and exemplified by application in a reliability analysis of a notional flame tube