Skalendokumentation der Schüler- und Lehrerbefragung im Rahmen des Projektes "Komm Mit - Fördern statt Sitzenbleiben"

Die vorliegende Skalendokumentation informiert über die Instrumente, die innerhalb der wissenschaftlichen Begleitung der Initiative "Komm Mit - Fördern statt sitzenbleiben" zum Zeitpunkt der ersten Datenerhebung eingesetzt wurden. "Komm Mit - Fördern statt Sitzenbleiben" ist eine landesweite Initiative in NRW, deren Ziel die Reduzierung der Sitzenbleiberquote ist. Von Januar bis März 2009 fand an 70 ausgewählten Schulen eine Fragebogenerhebung von Achtklässlern sowie des gesamten Lehrerkollegiums statt. Insgesamt urteilten ca. 2000 Schülerinnen und Schüler über die im Fragenbogen enthaltenen Aussagen zu motivationalen und emotionalen Voraussetzungen sowie über die Unterrichtsqualität. Der Lehrerfragebogen umfasste Aussagen zur Schul- und Unterrichtsqualität sowie zu Merkmalen der Lehrerschaft. Die einzelnen Bereiche werden durch verschiedene Items abgedeckt. In der Skalendokumentation werden die Skalen und die dazugehörigen Items dargestellt. Ferner sind die Gütekriterien der Skalen sowie die deskriptiven Kennwerte beschrieben. Die Instrumente der Befragungen wurden zum einen unverändert aus bewährten Studien übernommen. Zum anderen wurden Items umformuliert oder neue Items entwickelt. Auf die Quellen der Instrumente wird im Text jeweils verwiesen

Classical surrogates for quantum learning models

The advent of noisy intermediate-scale quantum computers has put the search for possible applications to the forefront of quantum information science. One area where hopes for an advantage through near-term quantum computers are high is quantum machine learning, where variational quantum learning models based on parametrized quantum circuits are discussed. In this work, we introduce the concept of a classical surrogate, a classical model which can be efficiently obtained from a trained quantum learning model and reproduces its input-output relations. As inference can be performed classically, the existence of a classical surrogate greatly enhances the applicability of a quantum learning strategy. However, the classical surrogate also challenges possible advantages of quantum schemes. As it is possible to directly optimize the ansatz of the classical surrogate, they create a natural benchmark the quantum model has to outperform. We show that large classes of well-analyzed re-uploading models have a classical surrogate. We conducted numerical experiments and found that these quantum models show no advantage in performance or trainability in the problems we analyze. This leaves only generalization capability as possible point of quantum advantage and emphasizes the dire need for a better understanding of inductive biases of quantum learning models.Comment: 4 pages, 3 figure

Classical Surrogates for Quantum Learning Models

The advent of noisy intermediate-scale quantum computers has put the search for possible applications to the forefront of quantum information science. One area where hopes for an advantage through near-term quantum computers are high is quantum machine learning, where variational quantum learning models based on parametrized quantum circuits are discussed. In this work, we introduce the concept of a classical surrogate, a classical model which can be efficiently obtained from a trained quantum learning model and reproduces its input-output relations. As inference can be performed classically, the existence of a classical surrogate greatly enhances the applicability of a quantum learning strategy. However, the classical surrogate also challenges possible advantages of quantum schemes. As it is possible to directly optimize the Ansatz of the classical surrogate, they create a natural benchmark the quantum model has to outperform. We show that large classes of well-analyzed reuploading models have a classical surrogate. We conducted numerical experiments and found that these quantum models show no advantage in performance or trainability in the problems we analyze. This leaves only generalization capability as a possible point of quantum advantage and emphasizes the dire need for a better understanding of inductive biases of quantum learning models

Tribological mechanisms of slurry abrasive wear

Abrasive wear mechanisms—including two-body and three-body abrasion—dominate the performance and lifespan of tribological systems in many engineering fields, even of those operating in lubricated conditions. Bearing steel (100Cr6) pins and discs in a flat-on-flat contact were utilized in experiments together with 5 and 13 µm Al$_{2}$O$_{3}$-based slurries as interfacial media to shed light on the acting mechanisms. The results indicate that a speed-induced hydrodynamic effect occurred and significantly altered the systems’ frictional behavior in tests that were performed using the 5 µm slurry. Further experiments revealed that a speed-dependent hydrodynamic effect can lead to a 14% increase in film thickness and a decrease in friction of around 2/3, accompanied by a transition from two-body abrasion to three-body abrasion and a change in wear mechanism from microcutting and microploughing to fatigue wear. Surprisingly, no correlation could be found between the total amount of wear and the operating state of the system during the experiment; however, the wear distribution over pin and disc was observed to change significantly. This paper studies the influence of the hydrodynamic effect on the tribological mechanism of lubricated abrasive wear and also highlights the importance to not only consider a tribological systems’ global amount of wear

Taxing away M&A : the effect of corporate capital gains taxes on acquisition activity

Taxing capital gains is an important obstacle to the efficient allocation of resources because it imposes a transaction cost on the vendor which locks in appreciated assets by raising the vendor’s reservation price in prospective transactions. For M&As, this effect has been intensively studied with regard to shareholder taxation, whereas empirical evidence on the effect of capital gains taxes paid by corporations is scarce. This paper analyzes how corporate level taxation of capital gains affects inter-corporate M&As. Studying several substantial tax reforms in a panel of 30 countries for the period of 2002-2013, we identify a significant lock-in effect. Results from estimating a Poisson pseudo-maximumlikelihood (PPML) model suggest that a one percentage point decrease in the corporate capital gains tax rate would raise both the number and the total deal value of acquisitions by about 1.1% per year. We use this result to estimate an efficiency loss resulting from corporate capital gains taxation of 3.06 bn USD per year in the United States

Modeling of Fluctuations in Dynamical Optoelectronic Device Simulations within a Maxwell-Density Matrix Langevin Approach

We present a full-wave Maxwell-density matrix simulation tool including c-number stochastic noise terms for the modeling of the spatiotemporal dynamics in active photonic devices, such as quantum cascade lasers (QCLs) and quantum dot (QD) structures. The coherent light-matter interaction in such devices plays an important role in the generation of frequency combs and other nonlinear and nonclassical optical phenomena. Since the emergence of nonlinear and nonclassical features is directly linked to the noise properties, detailed simulations of the noise characteristics are required for the development of low-noise quantum optoelectronic sources. Our semiclassical simulation framework is based on the Lindblad equation for the electron dynamics, coupled with Maxwell's equations for the optical propagation in the laser waveguide. Fluctuations arising from interactions of the optical field and quantum system with their reservoirs are treated within the quantum Langevin theory. Here, the fluctuations are included by adding stochastic c-number terms to the Maxwell-density matrix equations. The implementation in the mbsolve dynamic simulation framework is publicly available.Comment: 18 pages, 5 figure

Effects of territorial and worldwide corporation tax systems on outbound M&As

Repatriation taxes reduce the competitiveness of multinational firms from tax credit countries when bidding for targets in low tax countries. This comparative disadvantage with respect to bidders from exemption countries violates ownership neutrality, which results in production inefficiencies due to second-best ownership structures. This paper empirically estimates the magnitude of these effects. The abolishment of repatriation taxes in Japan and in the U.K. in 2009 has increased the number of acquisitions abroad by Japanese and British firms by 31.9% and 3.9 %, respectively. A similar policy switch in the U.S. is simulated to increase the number of U.S. cross-border acquisition by 17.1 %. We estimate the yearly gain in efficiency to be around 525 million dollar due to the Japanese reform and 13.5 million dollar due to the U.K. reform. Simulating such a reform for the U.S. results in a yearly efficiency gain of 1134 million dollar

Coulomb Branch Amplitudes from a Deformed Amplituhedron Geometry

The Amplituhedron provides, via geometric means, the all-loop integrand of scattering amplitudes in maximally supersymmetric Yang-Mills theory. Unfortunately, dimensional regularization, used conventionally for integration, breaks the beautiful geometric picture. This motivates us to propose a 'deformed' Amplituhedron. Focusing on the four-particle amplitude, we introduce two deformation parameters, which can be interpreted as particle masses. We provide evidence that the mass pattern corresponds to a specific choice of vacuum expectation values on the Coulomb branch. The deformed amplitude is infrared finite, making the answer well-defined in four dimensions. Leveraging four-dimensional integration techniques based on differential equations, we compute the amplitude up to two loops. In the limit where the deformation parameters are taken to zero, we recover the known Bern-Dixon-Smirnov amplitude. In the limit where only one deformation parameter is taken to zero, we find a connection to the angle-dependent cusp anomalous dimension.Comment: 6 pages, 2 figure