Level crossing problems and drift reliability

Reliability of products is often determined by special technical or physical drift parameters. Suitable stochastic processes are applied to model such drift processes. An failure can be observed when the drift process leaves a given region at the first time. Then the lifetime is the random time to first exit. Applying the first exit theory it is possible to find the type of lifetime distribution. Further the parameters of the lifetime distribution are to be estimated by observations of realisations of the underlying drift process.     

The spatial product of Arveson systems is intrinsic

We prove that the spatial product of two spatial Arveson systems is independent of the choice of the reference units. This also answers the same question for the minimal dilation of the Powers sum of two spatial CP-semigroups: It is independent up to cocycle conjugacy.     

Geometric combinatorics of Weyl groupoids

We extend properties of the weak order on finite Coxeter groups to Weyl groupoids admitting a finite root system. In particular, we determine the topological structure of intervals with respect to weak order, and show that the set of morphisms with fixed target object forms an ortho-complemented meet semilattice. We define the Coxeter complex of a Weyl groupoid with finite root system and show that it coincides with the triangulation of a sphere cut out by a simplicial hyperplane arrangement. As a consequence, one obtains an algebraic interpretation of many hyperplane arrangements that are not reflection arrangements.     

Myelination in the absence of UDP-galactose:ceramide galactosyl-transferase and fatty acid 2 -hydroxylase

Background  

The sphingolipids galactosylceramide (GalCer) and sulfatide are major myelin components and are thought to play important roles in myelin function. The importance of GalCer and sulfatide has been validated using UDP-galactose:ceramide galactosyltransferase-deficient (Cgt ^-/-) mice, which are impaired in myelin maintenance. These mice, however, are still able to form compact myelin. Loss of GalCer and sulfatide in these mice is accompanied by up-regulation of 2-hydroxylated fatty acid containing (HFA)-glucosylceramide in myelin. This was interpreted as a partial compensation of the loss of HFA-GalCer, which may prevent a more severe myelin phenotype. In order to test this hypothesis, we have generated Cgt ^-/- mice with an additional deletion of the fatty acid 2-hydroxylase (Fa2h) gene.     

Annealing effects in commercial aluminium hot-rolled 7075(–Sc–Zr) alloys

In the present work, the effect of hot rolling (at temperature 300 °C/60 min) on mechanical, thermal properties, microstructure and recrystallization behaviour of the commercial AlZnMgCuFe(ScZr) (7075-Sc,Zr) alloys was investigated. Microhardness together with differential scanning calorimetry measurements was compared to microstructure development that was observed by transmission and scanning electron microscopy and electron backscatter diffraction. Microstructure observation proved two types of eutectic phase (T-phase and Mn,Fe,Si-containing phase) at (sub)grain boundaries in hot-rolled alloys. The grain size was?~?20 μm in the AlZnMgCuFeScZr and?~?1000 μm in the AlZnMgCuFe alloy. Sc,Zr-addition in hot-rolled AlZnMgCuFe(ScZr) alloys significantly refined the grains. Primary multilayer Al₃(Sc,Zr) particles precipitated during casting and subsequent cooling in the alloy with Sc,Zr-addition. These particles were stable up to 450 °C. No changes of microhardness values (in accuracy of measurement) from room temperature up to 450 °C in the alloys were observed there. Thus, the probable presence of these secondary Al₃(Sc,Zr) particles is most likely the reason of hardening (ΔHV?≈?20) of the AlZnMgCuFeScZr alloy. A little higher electrochemical potential was measured for AlZnMgCuFeScZr alloy (??1144 mV) than for AlZnMgCuFe alloy (??1171 mV). One exothermic process was observed in hot-rolled alloys; apparent activation energy of this process was calculated as?~?100 kJ mol^?1. Additional precipitation and/or coarsening of S-phase together with precipitation of T-phase are probably connected with the exothermic process. Sc,Zr-addition has a significant antirecrystallization effect. No recrystallization was observed in the hot-rolled AlZnMgCuFeScZr alloy, neither after annealing at 350 °C/10 h nor after annealing at 450 °C/10 h. A partial recrystallization effect of the hot-rolled AlZnMgCuFe alloy is clearly registered after annealing at 350 °C/10 h and occurs very strongly after annealing at 450 °C/10 h.

     

Der Einflu? von Eigen- und Fremddotierung des CdTe auf den Reaktionsmechanismus der doppelten Umsetzung zwischen PbSe und CdTe

Ohne Zusammenfassung     

Der Einfluß von Eigen- und Fremddotierung des CdTe auf den Reaktionsmechanismus der doppelten Umsetzung zwischen PbSe und CdTe

Ohne Zusammenfassung