Anisotropic excitonic effects in the energy loss function of hexagonal boron nitride

We demonstrate that the valence energy-loss function of hexagonal boron nitride (hBN) displays a strong anisotropy in shape, excitation energy and dispersion for momentum transfer q parallel or perpendicular to the hBN layers. This is manifested by e.g. an energy shift of 0.7 eV that cannot be captured by single-particle approaches and is a demonstration of a strong anisotropy in the two-body electron-hole interaction. Furthermore, for in-plane directions of q we observe a splitting of the -plasmon in the M direction that is absent in the K direction and this can be traced back to band-structure effects.Comment: 10 pages, 4 figure

Partitioning 3-homogeneous latin bitrades

A latin bitrade $(T^{\diamond}, T^{\otimes})$ is a pair of partial latin squares which defines the difference between two arbitrary latin squares $L^{\diamond} \supseteq T^{\diamond}$ and $L^{\diamond} \supseteq T^{\otimes}$ of the same order. A 3-homogeneous bitrade $(T^{\diamond}, T^{\otimes})$ has three entries in each row, three entries in each column, and each symbol appears three times in $T^{\diamond}$. Cavenagh (2006) showed that any 3-homogeneous bitrade may be partitioned into three transversals. In this paper we provide an independent proof of Cavenagh's result using geometric methods. In doing so we provide a framework for studying bitrades as tessellations of spherical, euclidean or hyperbolic space.Comment: 13 pages, 11 figures, fixed the figures. Geometriae Dedicata, Accepted: 13 February 2008, Published online: 5 March 200

Size Dependence of Domain Pattern Transfer in Multiferroic Heterostructures

Magnetoelectric coupling in multiferroic heterostructures can produce large lateral modulations of magnetic anisotropy enabling the imprinting of ferroelectric domains into ferromagnetic films. Exchange and magnetostatic interactions within ferromagnetic films oppose the formation of such domains. Using micromagnetic simulations and a one-dimensional model, we demonstrate that competing energies lead to the breakdown of domain pattern transfer below a critical domain size. Moreover, rotation of the magnetic field results in abrupt transitions between two scaling regimes with different magnetic anisotropy. The theoretical predictions are confirmed by experiments on CoFeB/BaTiO3 heterostructures.Peer reviewe

Multilingual speech recognition for the elderly: The AALFred personal life assistant

The PaeLife project is a European industry-academia collaboration in the framework of the Ambient Assisted Living Joint Programme (AAL JP), with a goal of developing a multimodal, multilingual virtual personal life assistant to help senior citizens remain active and socially integrated. Speech is one of the key interaction modalities of AALFred, the Windows application developed in the project; the application can be controlled using speech input in four European languages: French, Hungarian, Polish and Portuguese. This paper briefly presents the personal life assistant and then focuses on the speech-related achievements of the project. These include the collection, transcription and annotation of large corpora of elderly speech, the development of automatic speech recognisers optimised for elderly speakers, a speech modality component that can easily be reused in other applications, and an automatic grammar translation service that allows for fast expansion of the automatic speech recognition functionality to new languages.info:eu-repo/semantics/publishedVersio

X-ray Raman scattering study of aligned polyfluorene

We present a non-resonant inelastic x-ray scattering study at the carbon K-edge on aligned poly[9,9-bis(2-ethylhexyl)-fluorene-2,7-diyl] and show that the x-ray Raman scattering technique can be used as a practical alternative to x-ray absorption measurements. We demonstrate that this novel method can be applied to studies on aligned $\pi$-conjugated polymers complementing diffraction and optical studies. Combining the experimental data and a very recently proposed theoretical scheme we demonstrate a unique property of x-ray Raman scattering by performing the symmetry decomposition on the density of unoccupied electronic states into $s$- and $p$-type symmetry contributions.Comment: 19 pages, 8 figure

Transformative Pedagogies for Sustainable Development

Transformative pedagogies for sustainable development encourage learners to change the direction of development that seems to be inevitable by enhancing their awareness, understanding of complexities, empathy, compassion and empowermentPeer reviewe

Reversible Electric-Field-Driven Magnetic Domain-Wall Motion

Control of magnetic domain-wall motion by electric fields has recently attracted scientific attention because of its potential for magnetic logic and memory devices. Here, we report on a new driving mechanism that allows for magnetic domain-wall motion in an applied electric field without the concurrent use of a magnetic field or spin-polarized electric current. The mechanism is based on elastic coupling between magnetic and ferroelectric domain walls in multiferroic heterostructures. Pure electric-field-driven magnetic domain-wall motion is demonstrated for epitaxial Fe films on BaTiO3 with in-plane and out-of-plane polarized domains. In this system, magnetic domain-wall motion is fully reversible and the velocity of the walls varies exponentially as a function of out-of-plane electric-field strength.Peer reviewe