Diskriminierungsbereitschaft in der beruflichen Bildung: Ergebnisse und Folgerungen aus einer Betriebsbefragung

"Strukturen und Praktiken, die zu Diskriminierung aufgrund askriptiver Merkmale führen, stehen in einem Widerspruch zum menschenrechtlich fundamentalen Diskriminierungsverbot und sie konterkarieren den Anspruch auf eine meritokratische Zuweisung sozialer Positionen unter Bedingungen der Chancengleichheit. Im vorliegenden Beitrag wird auf der Grundlage einer Betriebsbefragung aufgezeigt, dass dieser Anspruch im Bereich der beruflichen Bildung nicht eingelöst wird, sondern eine Diskriminierung migrantischer Jugendlicher nachweisbar ist, die über die Folgeeffekte schulischer Benachteiligung hinausreicht. Davon betroffen sind insbesondere Muslime und Muslima, deren Diskriminierung in einem erheblichen Umfang offen deklariert und als sozial zulässig wahrgenommen wird. Gezeigt wird weiter, dass Diskriminierung bei der Lehrstellenvergabe auch als Ergebnis von Ausschlussprozessen verstanden werden kann, deren Grundlage die Wahrnehmung migrantischer Jugendlicher als problematische Fremde ist." (Autorenreferat)"Social structures and practices that entail discrimination based on ascribed attributes violate the prohibition of discrimination, a proclaimed human right fundamental for modern societies, and thwart the postulated meritocratic attainment of social positions based on equal opportunities. This article documents the results of a survey of firms with regard to their criteria for vocational training candidate selection which show that meritocratic principles are not being upheld within the scope of vocational training. Rather, they provide evidence for the discrimination of juveniles with a so called 'migration Background' that reaches beyond the effects of discrimination during years of school education. In particular, this is apparent for Muslims whose discrimination is frequently openly admitted and considered to be socially acceptable. Furthermore this article argues that discrimination related to the offering of apprenticeships can be understood as resulting of derived processes whose basis is the perception of immigrants as being problematic strangers." (author's abstract

Epitaxially grown p‐type silicon wafers ready for cell efficiencies exceeding 25%

Combining the advantages of a high‐efficiency solar cell concept and a low carbon footprint base material is a promising approach for highly efficient, sustainable, and cost‐effective solar cells. In this work, we investigate the suitability of epitaxially grown p‐type silicon wafers for solar cells with tunnel oxide passivating contact rear emitter. As a first proof of principle, an efficiency limiting bulk recombination analysis of epitaxially grown p‐type silicon wafers deposited on high quality substrates (EpiRef) unveils promising cell efficiency potentials exceeding 25% for three different base resistivities of 3, 14, and 100 Ω cm. To understand the remaining limitations in detail, concentrations of metastable defects Fe i , CrB and BO are assessed by lifetime‐calibrated photoluminescence imaging and their impact on the overall recombination is evaluated. The EpiRef wafers’ efficiency potential is tracked along the solar cell fabrication process to quantify the impact of high temperature treatments on the material quality. We observe large areas with few structural defects on the wafer featuring lifetimes exceeding 10 ms and an efficiency potential of 25.8% even after exposing the wafer to a thermal oxidation at 1050 °C

On the problem of supersonic gas flow in two-dimensional channel with the oscillating upper wall

In the present paper we solve the problem of supersonic gas flow in two-dimensional channel with the moving upper wall making oscillations according to the harmonic law. In order to get a numerical solution for gas dynamics equations we have implemented a difference scheme with space and time approximation of the first order and one with space approximation of the second order. Depending on a type of harmonic law and initial gas inflow conditions, the peculiarities of angle-shock wave propagation in moving curvilinear domains have been investigated. It has been determined that the increase of oscillation amplitude causes the increase of shock wave intensity. It has been shown that under particular oscillation amplitude the moving wall has practically no effect on the flow within the domain

Super-enhancer-based identification of a BATF3/IL-2R-module reveals vulnerabilities in anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL), an aggressive CD30-positive T-cell lymphoma, comprises systemic anaplastic lymphoma kinase (ALK)-positive, and ALK-negative, primary cutaneous and breast implant-associated ALCL. Prognosis of some ALCL subgroups is still unsatisfactory, and already in second line effective treatment options are lacking. To identify genes defining ALCL cell state and dependencies, we here characterize super-enhancer regions by genome-wide H3K27ac ChIP-seq. In addition to known ALCL key regulators, the AP-1-member BATF3 and IL-2 receptor (IL2R)-components are among the top hits. Specific and high-level IL2R expression in ALCL correlates with BATF3 expression. Confirming a regulatory link, IL-2R-expression decreases following BATF3 knockout, and BATF3 is recruited to IL2R regulatory regions. Functionally, IL-2, IL-15 and Neo-2/15, a hyper-stable IL-2/IL-15 mimic, accelerate ALCL growth and activate STAT1, STAT5 and ERK1/2. In line, strong IL-2Rα-expression in ALCL patients is linked to more aggressive clinical presentation. Finally, an IL-2Rα-targeting antibody-drug conjugate efficiently kills ALCL cells in vitro and in vivo. Our results highlight the importance of the BATF3/IL-2R-module for ALCL biology and identify IL-2Rα-targeting as a promising treatment strategy for ALCL

16p11.2 600 kb Duplications confer risk for typical and atypical Rolandic epilepsy

Rolandic epilepsy (RE) is the most common idiopathic focal childhood epilepsy. Its molecular basis is largely unknown and a complex genetic etiology is assumed in the majority of affected individuals. The present study tested whether six large recurrent copy number variants at 1q21, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 previously associated with neurodevelopmental disorders also increase risk of RE. Our association analyses revealed a significant excess of the 600 kb genomic duplication at the 16p11.2 locus (chr16: 29.5-30.1 Mb) in 393 unrelated patients with typical (n = 339) and atypical (ARE; n = 54) RE compared with the prevalence in 65 046 European population controls (5/393 cases versus 32/65 046 controls; Fisher's exact test P = 2.83 × 10−6, odds ratio = 26.2, 95% confidence interval: 7.9-68.2). In contrast, the 16p11.2 duplication was not detected in 1738 European epilepsy patients with either temporal lobe epilepsy (n = 330) and genetic generalized epilepsies (n = 1408), suggesting a selective enrichment of the 16p11.2 duplication in idiopathic focal childhood epilepsies (Fisher's exact test P = 2.1 × 10−4). In a subsequent screen among children carrying the 16p11.2 600 kb rearrangement we identified three patients with RE-spectrum epilepsies in 117 duplication carriers (2.6%) but none in 202 carriers of the reciprocal deletion. Our results suggest that the 16p11.2 duplication represents a significant genetic risk factor for typical and atypical R

Determining crystal structures through crowdsourcing and coursework

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality

Amorphes Siliciumkarbid für photovoltaische Anwendungen

Within this work amorphous SiC is investigated for its applicability in photovoltaic devices. The temperature stability and dopability of SiC makes this material very attractive for applications in this area. Physical basics of amorphous SiC networks and plasma processes are discussed and first measurements with FTIR of the different layer types show the complexity of the network. The special features of the plasma reactor such as high temperature deposition and two-source excitation are also discussed. Beside plasma etching I furthermore tested the etching behaviour of stoichiometric SiC in different wet chemical etching solutions. The results show that etching of SiC, especially when it is already annealed, is very difficult for both etching processes. Furthermore, stress measurements of our layers deposited and annealed at different temperatures show the change of stress from compressive

Silicon nanocrystals embedded in silicon carbide for tandem solar cell applications

Tandem solar cells are potentially much more efficient than the silicon solar cells that currently dominate the market but require materials with different bandgaps. This thesis presents work on silicon nanocrystals (Si-NC) embedded in silicon carbide (SiC), which are expected to have a higher bandgap than bulk Si due to quantum confinement, with a view to using them in the top cell of a tandem cell. The strong photoluminescence (PL) of precursor films used to prepare Si-NC in SiC (Si-NC/SiC) was markedly reduced upon Si-NC formation due to simultaneous out-diffusion of hydrogen that passivated dangling bonds. This cannot be reversed by hydrogenation and leads to weak PL that is due to, and limited by, non-paramagnetic defects, with an estimated quantum yield of ≤5×10-7. Optical interference was identified as a substantial artefact and a method proposed to account for this. Majority carrier transport was found to be Ohmic at all temperatures for a wide range of samples. Hydrogenation decreases dangling bond density and increases conductivity up to 1000 times. The temperature-dependence of conductivity is best described by a combination of extended-state and variable-range hopping transport where the former takes place in the Si nanoclusters. Furthermore, n-type background doping by nitrogen and/or oxygen was identified. In the course of developing processing steps for Si-NC-based tandem cells, a capping layer was developed to prevent oxidation of Si-NC/SiC, and diffusion of boron and phosphorus in nanocrystalline SiC was found to occur via grain boundaries with an activation energy of 5.3±0.4 eV and 4.4±0.7 eV, respectively. Tandem cells with a Si-NC/SiC top cell and bulk Si bottom cell were prepared that exhibited open-circuit voltages Voc of 900 mV and short-circuit current densities of 0.85 mAcm-2. Performance was limited by photocurrent collection in the top cell; however, the Voc obtained demonstrates tandem cell functionality.This thesis is not currently available via ORA

Reorganization of Porous Silicon. Effect on Epitaxial Layer Quality and Detachment

Cost reduction is still a main goal in solar cell research and can be achieved by going towards thinner silicon bulk material. One way to avoid kerf loss and to reach thicknesses of less than 50 μm is a lift-off approach using porous silicon and epitaxial thickening for silicon foil fabrication. The porous layer structure requires a reorganization step that was varied in this work to optimize the detachment properties and the crystal quality of the epitaxial Si film. All processes were carried out in a quasi-inline Atmospheric Pressure Chemical Vapour Deposition (APCVD) reactor. Cross–sections were observed to see if the porous layer shows the desired structure. Stacking fault densities in epitaxial layers deposited on porous silicon layers significantly decrease with increasing reorganization time but are at least one order of magnitude higher than in epitaxial layers deposited on polished wafers. Microwave photoconductive decay (MWPCD) measurements and photo luminescence (PL) imaging were carried out to determine the effective carrier lifetimes of the detached foils and to correlate them with stacking faults and cracks. A detached 40 μm thin silicon foil with an averaged effective carrier lifetime of 22 μs is shown which corresponds to a diffusion length of over 200 μm. This investigation shows that silicon foils deposited in a quasi-inline APCVD reactor exhibit good detachment properties and a good crystal quality, which is both needed for high efficiency solar cell processing