Modulation of the Work Function by the Atomic Structure of Strong Organic Electron Acceptors on H-Si(111)

Advances in hybrid organic/inorganic architectures for optoelectronics can be achieved by understanding how the atomic and electronic degrees of freedom cooperate or compete to yield the desired functional properties. Here we show how work-function changes are modulated by the structure of the organic components in model hybrid systems. We consider two cyano-quinodimethane derivatives (F4-TCNQ and F6-TCNNQ), which are strong electron-acceptor molecules, adsorbed on H-Si(111). From systematic structure searches employing range-separated hybrid HSE06 functional including many body van der Waals contributions, we predict that despite their similar composition, these molecules adsorb with significantly different densely-packed geometries in the first layer, due to strong intermolecular interaction. F6-TCNNQ shows a much stronger intralayer interaction (primarily due to van der Waals contributions) than F4-TCNQ in multilayered structures. The densely-packed geometries induce a large interface-charge rearrangement that result in a work-function increase of 1.11 and 1.76 eV for F4-TCNQ and F6-TCNNQ, respectively. Nuclear fluctuations at room temperature produce a wide distribution of work-function values, well modeled by a normal distribution with {\sigma}=0.17 eV. We corroborate our findings with experimental evidence of pronounced island formation for F6-TCNNQ on H-Si(111) and with the agreement of trends between predicted and measured work-function changes

Determine Task Demand from Brain Activity

Our society demands ubiquitous mobile devices that offer seamless interaction with everybody, everything, everywhere, at any given time. However, the effectiveness of these devices is limited due to their lack of situational awareness and sense for the users ’ needs. To overcome this problem we develop intelligent transparent human-centered systems that sense, analyze, and interpret the user’s needs. We implemented learning approaches that derive the current task demand from the user’s brain activity by measuring the electroencephalogram. Using Support Vector Machines we can discriminate high versus low task demand with an accuracy of 92.2 % in session dependent experiments, 87.1 % in session independent experiments, and 80.0 % in subject independent experiments. To make brain activity measurements less cumbersome, we built a comfortable headband with which we achieve 69 % classification accuracy on the same task.

Kiri Karl Morgensternile, Kiel

http://tartu.ester.ee/record=b1808526~S1*es

Vorbereitung auf das Unterrichten mit digitalen Medien: szenarien-basierte Selbsteinschätzung in der Aus- und Weiterbildung von Lehrkräften

Teachers’ technology-related skills are often measured with self-assessments. However, self-assessments are often criticised for being inaccurate and biased. Scenario-based self-assessment is a promising approach to make self-assessment more accurate and less biased. In this study with N = 552 inservice and student teachers, we validated a scenario-based self-assessment instrument IN.K19+ for teachers. The instrument enables scenario-based self-assessment of instrumental and critical digital skills and technology-related teaching skills for teachers. In a confirmatory factor analysis, we show that the instrument has sufficient factorial validity. To test the predictive validity of the instrument, we examined the instruments’ relationship to the frequency of technology use during teaching and teacher-initiated student learning activities involving digital technologies. Results from structural equation modelling show that instrumental digital skills and technology-related teaching skills are positively related to the frequency of digital technology use during teaching, while critical digital skills are not. In terms of the initiation of student learning activities, instrumental and critical digital skills show relationships with initiating student learning activities that include lower cognitive engagement. Technology-related teaching skills are related to initiating learning activities that indicate higher cognitive engagement. The results show that instrumental and critical digital skills play an important role with respect to the basic use of digital technologies in the classroom, while technology-related teaching skills turn out to be crucial for more complex scenarios of digital technology use. This pattern of findings supports the predictive validity of the IN.K19+ instrument

Primal and Dual Methods for Unit Commitment in a Hydro-Thermal Power System

The unit commitment problem in a power generation system comprising thermal and pumped-storage hydro units is adressed. A large-scale mixed-integer optimization model for unit commitment in a real power system is developed and solved by primal and dual approaches. Both solution methods employ state-of-the-art algorithms and software. Results of test runs are reported

4SALE – A tool for synchronous RNA sequence and secondary structure alignment and editing

BACKGROUND: In sequence analysis the multiple alignment builds the fundament of all proceeding analyses. Errors in an alignment could strongly influence all succeeding analyses and therefore could lead to wrong predictions. Hand-crafted and hand-improved alignments are necessary and meanwhile good common practice. For RNA sequences often the primary sequence as well as a secondary structure consensus is well known, e.g., the cloverleaf structure of the t-RNA. Recently, some alignment editors are proposed that are able to include and model both kinds of information. However, with the advent of a large amount of reliable RNA sequences together with their solved secondary structures (available from e.g. the ITS2 Database), we are faced with the problem to handle sequences and their associated secondary structures synchronously. RESULTS: 4SALE fills this gap. The application allows a fast sequence and synchronous secondary structure alignment for large data sets and for the first time synchronous manual editing of aligned sequences and their secondary structures. This study describes an algorithm for the synchronous alignment of sequences and their associated secondary structures as well as the main features of 4SALE used for further analyses and editing. 4SALE builds an optimal and unique starting point for every RNA sequence and structure analysis. CONCLUSION: 4SALE, which provides an user-friendly and intuitive interface, is a comprehensive toolbox for RNA analysis based on sequence and secondary structure information. The program connects sequence and structure databases like the ITS2 Database to phylogeny programs as for example the CBCAnalyzer. 4SALE is written in JAVA and therefore platform independent. The software is freely available and distributed from the website a