University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Membrane. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Fast context-aware recommendations with factorization machines

Abstract: The situation in which a choice is made is an important information for recommender systems. Context-aware recommenders take this information into account to make predictions. So far, the best performing method for context-aware rating prediction in terms of predictive accuracy is Multiverse Recommendation based on the Tucker tensor factorization model. However this method has two drawbacks: (1) its model complexity is exponential in the number of context variables and polynomial in the size of the factorization and (2) it only works for categorical context variables. On the other hand there is a large variety of fast but specialized recommender methods which lack the generality of context-aware methods. We propose to apply Factorization Machines (FMs) to model contextual information and to provide context-aware rating predictions. This approach results in fast context-aware recommendations because the model equation of FMs can be computed in linear time both in the number of context variables and the factorization size. For learning FMs, we develop an iterative optimization method that analytically finds the least-square solution for one parameter given the other ones. Finally, we show empirically that our approach outperforms Multiverse Recommendation in prediction quality and runtime.

The Interplay Between Goal Intentions and Implementation Intentions

Abstract: Two studies tested whether action control by implementation intentions is sensitive to the activation and strength of participants’ underlying goal intentions. In Study 1, participants formed implementation intentions (or did not) and their goal intentions were measured. Findings revealed a significant interaction between implementation intentions and the strength of respective goal intentions. Implementation intentions benefited the rate of goal attainment when participants had strong goal intentions but not when goal intentions were weak. Study 2 activated either a task-relevant or a neutral goal outside of participants’ conscious awareness and found that implementation intentions affected performance only when the relevant goal had been activated. These findings indicate that the rate of goal attainment engendered by implementation intentions takes account of the state (strength, activation) of people’s superordinate goal intentions.

Emotional transmission in the classroom : exploring the relationship between teacher and student enjoyment

Abstract: In this study, the authors examined the relationship between teacher and student enjoyment. Based on social-cognitive approaches to emotions, they hypothesized (a) that teacher enjoyment and student enjoyment within classrooms are positively linked and (b) that teacher enthusiasm mediates the relationship between teacher and student enjoyment. Self-reported enjoyment of mathematics classes was available from 1,542 students from 71 classrooms at 2 time points (Grades 7 and 8). At Time 2, mathematics teachers' reports of their enjoyment of teaching were available (N = 71), as well as student ratings of teacher enthusiasm. The findings were in line with theoretical expectations. Multilevel structural equation modeling showed that teacher and student enjoyment were positively related even when the authors adjusted for students' previous-class levels of mathematics enjoyment, and that the effect of teacher enjoyment on student enjoyment was mediated by teacher enthusiasm. Discussion centers on the practical implications for affective interactions in the classroom.

Photoelectrochromic windows and displays

Abstract: PHOTOCHROMIC materials1,2 change colour on absorption of light, whereas electrochromic materials3,4 change colour in response to an electrically induced change in oxidation state. Both classes of materials are being investigated for potential applications in displays, imaging devices and 'smart' windows5–8,15,16. Here we describe an alternative route to such applications, in which an electrochromic film and a photovoltaic film form the two electrodes of an electrochemical cell. The resulting structure exhibits photochromism, but unlike conventional photochromic films, the light-absorption process (in the photovoltaic film) is separate from the coloration process (in the electrochromic film): both may therefore be optimized individually. Moreover, as the coloration process in our cells requires an external electrical current between the two electrodes, the optical state of the cell—transparent, absorbing or, in the case of non-uniform illumination, patterned—can be stored when the circuit is open, or changed when the electrodes are connected.

Quantum State Reconstruction of the Single-Photon Fock State

Abstract: We have reconstructed the quantum state of optical pulses containing single photons using the method of phase-randomized pulsed optical homodyne tomography. The single-photon Fock state 1> was prepared using conditional measurements on photon pairs born in the process of parametric down-conversion. A probability distribution of the phase-averaged electric field amplitudes with a strongly non-Gaussian shape is obtained with the total detection efficiency of (55+/-1)%. The angle-averaged Wigner function reconstructed from this distribution shows a strong dip reaching classically impossible negative values around the origin of the phase space.