Inelastic Coulomb scattering rates due to acoustic and optical plasmon modes in coupled quantum wires

We report a theoretical study on the inelastic Coulomb scattering rate of an injected electron in two coupled quantum wires in quasi-one-dimensional doped semiconductors. Two peaks appear in the scattering spectrum due to the optical and the acoustic plasmon scattering in the system. We find that the scattering rate due to the optical plasmon mode is similar to that in a single wire but the acoustic plasmon scattering depends crucially on its dispersion relation at small $q$. Furthermore, the effects of tunneling between the two wires are studied on the inelastic Coulomb scattering rate. We show that a weak tunneling can strongly affect the acoustic plasmon scattering.Comment: 6 Postscript figure

Coulomb correlation effects in semiconductor quantum dots: The role of dimensionality

We study the energy spectra of small three-dimensional (3D) and two-dimensional (2D) semiconductor quantum dots through different theoretical approaches (single-site Hubbard and Hartree-Fock hamiltonians); in the smallest dots we also compare with exact results. We find that purely 2D models often lead to an inadequate description of the Coulomb interaction existing in realistic structures, as a consequence of the overestimated carrier localization. We show that the dimensionality of the dots has a crucial impact on (i) the accuracy of the predicted addition spectra; (ii) the range of validity of approximate theoretical schemes. When applied to realistic 3D geometries, the latter are found to be much more accurate than in the corresponding 2D cases for a large class of quantum dots; the single-site Hubbard hamiltonian is shown to provide a very effective and accurate scheme to describe quantum dot spectra, leading to good agreement with experiments.Comment: LaTeX 2.09, RevTeX, 25 pages, 9 Encapsulated Postscript figures. To be published in Physical Review

FaceHash: Face detection and robust hashing

In this paper, we introduce a concept to counter the current weakness of robust hashing with respect to cropping. We combine face detectors and robust hashing. By doing so, the detected faces become a subarea of the overall image which always can be found as long as cropping of the image does not remove the faces. As the face detection is prone to a drift effect altering size and position of the detected face, further mechanisms are needed for robust hashing. We show how face segmentation utilizing blob algorithms can be used to implement a face-based cropping robust hash algorithm

Stirmark Benchmark: Audio Watermarking Attacks

In this paper we will briefly present the architecture of a public automated evaluation service we are developing for still images, sound and video. We will also detail new tests that will be included in this platform. The set of tests is related to audio data and addresses the usual equalisation and normalisation but also time stretching, pitch shifting and specially designed audio attack algorithms. These attacks are discussed and results on watermark attacks and perceived quality after applying the attacks are provided

Generosity, peer-support, and positive development in youth

In adolescence, many physical, emotional, and cognitive changes bring along their own problems and risks. But they also offer the chance to develop new skills, including those connected with mindfulness, compassion, or generosity. Social relationships can support positive developments. Even in adolescence, family remains important, contributing to the satisfaction of basic needs. Peers can also support positive development and become particularly important in adolescence. With them, young people’s radius widens into a more comprehensive and differentiated social and physical environment. The newly acquired competences also promote the acceptance of responsibility. The social and physical environments become relevant learning fields for the integration of identity, values, and norms. Generosity as part of one’s own identity becomes a touchstone for positive development. In this paper, we discuss several forms and conditions of prosocial behavior as well as of generosity. We assign different internal conditions to “prosocial personality”, ranging from genetic or biological factors to self-efficacy. External factors for prosocial behavior and generosity are described. In everyday life, young people must feel needed and require places to show their new autonomous generosity skills. Being generous not only helps others: it also satisfies one’s own basic needs and thus contributes to positive development and well-being

Economic and ecological trade-offs of agricultural specialization at different spatial scales

AbstractSpecialization in agricultural systems can lead to trade-offs between economic gains and ecosystem functions. We suggest and explore a conceptual framework in which economic gains can be maximized when production activities are specialized at increasingly broader scales (from the household to the village, region or above), particularly when markets for outputs and inputs function well. Conversely, more specialization likely reduces biodiversity and significantly limits ecosystem functions. When agricultural specialization increases and moves to broader scales as a result of improved infrastructure and markets or other drivers, ecosystem functions can also be endangered at broader spatial scales. Policies to improve agricultural incomes may influence the level of specialization at different scales and thus affect the severity of the trade-offs. This paper takes Jambi province in Indonesia, a current hotspot of rubber and oil palm monoculture, as a case study to illustrate these issues. We empirically show that the level of specialization differs across scales with higher specialization at household and village levels and higher diversification towards the province level. We discuss ways to resolve trade-offs between economic gains and ecological costs, including landscape design, targeted policies, and adoption of long-term perspectives

A Modern Guide of Public Policy

Taken together, these 15 chapters provide a very rich but concise guide to both the empirical reality of public policy-making and the literature in the field. They set out and answer key questions ranging from basic definitions and assumptions to the nature of key actors and institutions, the mechanisms, tools and resources that make policies work, and the manner in which policies evolve and change over time. They present not only the state of the art of the topics treated, but also a source of inspiration for further theoretical advances and new research into this still young field of academic inquiry