Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon

The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that the electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction due to impurity scattering vanishes and the effect is therefore robust against disorder. The orbital Hall effect can lead to the accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.Comment: 4 page

Study-related Use of Instructional Videos by Undergraduate Engineering Students

[EN] In this paper, a questionnaire-based survey on the use of online videos by undergraduate engineering students for study-related purposes is presented. Over the last few years, a large number of instructional videos has been uploaded to websites such as YouTube. Due to the widespread distribution of high-speed internet connections and (mobile) devices, such as smartphones or laptops, which are nowadays routinely used by students, online videos are also frequently used in higher education. While much research on this subject focuses on Massive Open Online Courses (MOOCs) or flipped classroom approaches, this survey examines use of videos for self-study, complementary to traditional face-to-face courses. Furthermore, we analyze the acceptance of a characteristic video production style, which uses specific 3D animations to clarify complex connections between technical and mathematical aspects. The results indicate extensive use of short videos which address subjects that are particularly difficult for the students. This survey can help educators to develop an impression of current video use by undergraduate engineering students. In this paper, a questionnaire-based survey on the use of online videos by undergraduate engineering students for study-related purposes is presented. Especially over the last few years, a large number of instructional videos has been uploaded to websites such as YouTube. Due to the widespread distribution of high-speed internet connections and (mobile) devices, such as smartphones or laptops, which are nowadays routinely used by students, online videos are also frequently used in higher education. While much research on this subject focuses on Massive Open Online Courses (MOOCs) or flipped classroom approaches, this survey examines usage behavior concerning the apparently much more common use of videos for self-study, complementary to traditional face-to-face courses. Furthermore, we analyze the acceptance of a characteristic video production style using specific 3D animations to clarify complex connections between technical and mathematical aspects. The results indicate that short videos addressing subjects that are particularly difficult for the students are extensively used. Additionally, this survey can help educators to develop a realistic understanding of current video use by undergraduate engineering students.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Hennig, M.; Mertsching, B. (2018). Study-related Use of Instructional Videos by Undergraduate Engineering Students. Editorial Universitat Politècnica de València. 1377-1385. https://doi.org/10.4995/HEAD18.2018.8207OCS1377138

Innovative 3D Animations for Teaching Electromagnetic Field Theory and its Mathematics in Undergraduate Engineering

[EN] In this work, an innovative approach for the design and structuring of teaching videos systematically using 3D animations is presented. The approach focuses on the quantitative description of electromagnetic fields and the mathematical methods and competencies required for this purpose, exemplarily with regard to an undergraduate electrical engineering course during the initial phase of corresponding degree programs. An essential part of this course is the spatial and time-dependent description of electromagnetic fields. For this purpose, students have to work with multiple integrals in 3D space and in different coordinate systems. Such subjects are typically covered only later in mathematics courses and without a technical context, therefore leading to major difficulties for many students. The videos presented in this work are intended to support students and lecturers to work with these subjects in an instructive fashion. The 3D animations allow for effectively clarifying complex connections between technical and mathematical aspects. The videos and their specific design are discussed with regard to didactic and technical considerations. Additionally, their integration with existing interventions for the course is described.Hennig, M.; Mertsching, B. (2017). Innovative 3D Animations for Teaching Electromagnetic Field Theory and its Mathematics in Undergraduate Engineering. En Proceedings of the 3rd International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 625-632. https://doi.org/10.4995/HEAD17.2017.532762563

Pop-out and IOR in Static Scenes with Region Based Visual Attention

This paper proposes a novel approach to construct the saliency map by combining region-based maps of distinct features. The multiplication style feature fusion process in the natural visual attention is modelled as weighted average of the features under influence of the external top-down and the internal bottom-up inhibitions. The recently discovered aspect of feature-based inhibition is also included in the procedure of IOR along with the commonly implemented spatial and feature-map based inhibitions. Results obtained from the proposed method are compatible with the well known attention models but with the advantages of faster computation, direct usability of focus of attention in machine vision, and broader coverage of visually prominent objects

Generic Phase Diagram of Fermion Superfluids with Population Imbalance

It is shown by microscopic calculations for trapped imbalanced Fermi superfluids that the gap function has always sign changes, i.e., the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state like, up to a critical imbalance $P_c$, beyond which normal state becomes stable, at temperature T=0. A phase diagram is constructed in $T$ vs $P$, where the BCS state without sign change is stable only at $T\neq 0$. We reproduce the observed bimodality in the density profile to identify its origin and evaluate $P_c$ as functions of $T$ and the coupling strength. These dependencies match with the recent experiments.Comment: 5 pages, 5 figures, replaced by the version to appear in PR

Pop-out and IOR in Static Scenes with Region Based Visual Attention

This paper proposes a novel approach to construct the saliency map by combining region-based maps of distinct features. The multiplication style feature fusion process in the natural visual attention is modelled as weighted average of the features under influence of the external top-down and the internal bottom-up inhibitions. The recently discovered aspect of feature-based inhibition is also included in the procedure of IOR along with the commonly implemented spatial and feature-map based inhibitions. Results obtained from the proposed method are compatible with the well known attention models but with the advantages of faster computation, direct usability of focus of attention in machine vision, and broader coverage of visually prominent objects

One Dimensional Chain with Long Range Hopping

The one-dimensional (1D) tight binding model with random nearest neighbor hopping is known to have a singularity of the density of states and of the localization length at the band center. We study numerically the effects of random long range (power-law) hopping with an ensemble averaged magnitude \expectation{|t_{ij}|} \propto |i-j|^{-\sigma} in the 1D chain, while maintaining the particle-hole symmetry present in the nearest neighbor model. We find, in agreement with results of position space renormalization group techniques applied to the random XY spin chain with power-law interactions, that there is a change of behavior when the power-law exponent $\sigma$ becomes smaller than 2