Density functional theory for a model quantum dot: Beyond the local-density approximation

We study both static and transport properties of model quantum dots, employing density functional theory as well as (numerically) exact methods. For the lattice model under consideration the accuracy of the local-density approximation generally is poor. For weak interaction, however, accurate results are achieved within the optimized effective potential method, while for intermediate interaction strengths a method combining the exact diagonalization of small clusters with density functional theory is very successful. Results obtained from the latter approach yield very good agreement with density matrix renormalization group studies, where the full Hamiltonian consisting of the dot and the attached leads has to be diagonalized. Furthermore we address the question whether static density functional theory is able to predict the exact linear conductance through the dot correctly - with, in general, negative answer.Comment: 8 page

Karpik in the Bottle: Erklären Instanzen der Urteilsbildung den Kauf von Luxuswein?

Processes of valuation and evaluation are especially complex and un-certain in markets for unique products. Consider the purchase of a bottle of finewine. Each wine was produced in a certain region, on a particular soil, by a famouswine producer, employing methods handed down for centuries. How can consumerscompare unique products in order to make a choice? How is a market for singularproducts possible? According to Lucien Karpik’s economics of singularities, suchmarkets necessarily rely on social actors and artifacts providing knowledge on howto compare unique products, called judgment devices. To systematically assess theexplanatory contribution of Karpik’s approach, this paper empirically tests funda-mental propositions of the economics of singularities in a quantitative framework,examining the case of the demand for fine wine. The analysis provides ample sup-port for Karpik’s theory. First, wine demand is substantially correlated with the useof judgment devices. Second, the effects of judgment devices on product demandcannot be explained by information deficits, in line with the theoretical arguments.However, the analysis also reveals deviations from the theoretical expectations. Cer-tain judgment devices prove more important for the demand for higher priced winesthan predicted, whereas others play a more minor role. Furthermore, the use of judg-ment devices is substantially linked to social distinction, something Karpik’s theoryoverlooks.Bewertungsprozesse sind besonders komplex in Märkten füreinzigartige Produkte. Man nehme den Kauf einer Flasche Luxuswein. Jeder Weinwurde in einer bestimmten Region, von einem bekannten Weinproduzenten und mittraditionellen Produktionsmethoden hergestellt. Wie können Konsumentinnen undKonsumenten solche einzigartigen Produkte miteinander vergleichen? Wie ist einMarkt für singuläre Produkte möglich? Lucien Karpiks „Ökonomie des Einzigarti-gen“ argumentiert, dass solche Märkte auf Instanzen der Urteilsbildung angewiesensind, die Wissen zum Vergleich einzigartiger Produkte bereitstellen. Um den Erklä-rungsgehalt dieses Ansatzes zu testen, überprüft der Beitrag grundlegende Proposi-tionen von Karpiks Theorie für die Nachfrage nach Luxuswein mittels quantitativerMethoden. Die Analyse kann die Theorie zu weiten Teilen bestätigen. Die Nachfra-ge nach Luxuswein korreliert mit der Verwendung der Instanzen der Urteilsbildung.Im Einklang mit der Theorie sind die Effekte der Instanzen der Urteilsbildung aufdie Nachfrage nicht durch Informationsdefizite erklärbar. Es zeigen sich jedochauch Abweichungen. Gewisse Instanzen der Urteilsbildung sind wichtiger für dieNachfrage als erwartet, währenddessen andere eine kleinere Rolle spielen. Zudemsteht die Verwendung der Instanzen der Urteilsbildung mit Distinktionsprozessen inVerbindung, was in Karpiks Theorie vernachlässigt wird.On the Comparison of Unique Wines Fundamental Propositions of the Economics of Singularities Data, Measurement, Method The Use of Judgment Devices in the Market for Fine Wine: Empirical Results "Valuing the Unique": The Explanatory Contribution of the Economics of Singularities Notes Reference

Aspectos gerais da fotossensibilizacao hepatogena em bovinos.

A sensibilização da pele a luz devido, geralmente, a ação de certas doenças, plantas ou outras substancias, e denominada fotossensibilizacao (Stedman's Medical 1972). O primeiro registro sobre a ocorrência de fotossensibilizacao hepatogena em bovinos mantidos em pastagens de Brachiaria decumbens, na América do Sul, foi feito na Venezuela (Centro Internacional de Agricultura Tropical 1975), onde a doença ocasionou a morte de doze garrotes nos primeiros dias de pastejo. No Brasil, Hutton (s.d.lL) fez observações sobre casos desta doença no gado Nelore, em pastagens de B. decumbens, em Rio Verde de Goiás. O surto acometeu, principalmente, bezerros antes e depois da desmama. Alem desta primeira constatação, vários outros autores descreveram esta doença em bovinos em pastagem de B. decumbens.bitstream/item/138531/1/COT-19.pdfCNPG

Collision-free inverse kinematics of a 7 link cucumber picking robot

The paper presents results of research on inverse kinematics algorithms to be used in a functional model of a cucumber harvesting robot consisting of a redundant manipulator with one prismatic and six rotational joints (P6R). Within a first generic approach, the inverse kinematics problem was reformulated as a non-linear programming problem and solved with a generic algorithm. Solutions were easily obtained, but the considerable calculation time needed to solve the problem prevented on line implementation. To circumvent this problem, a second, less generic approach was developed consisting of a mixed numerical-analytic solution of the inverse kinematics problem exploiting the particular structure of the P6R manipulator. This approach facilitated rapid and robust calculation of the inverse kinematics of the cucumber harvester. During the early stages of the cucumber harvesting project, this inverse kinematics algorithm was used to off-line evaluate the ability of the robot to harvest cucumbers using 3D-information of a cucumber crop obtained in a real greenhouse. Thereafter, the algorithm was employed successfully in a functional model of the cucumber harvester to determine if cucumbers were hanging within the reachable workspace of the robot and to determine a collision-free harvest posture to be used for motion control of the manipulator during harvesting

Analysis of the influence of phase noise in MIMO OFDM based WLAN systems

The influence of phase noise (PN) on the performance of a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) based communication system is analyzed. A PN power weighting function is derived which indicates the influence of the different subcarriers and the shape of the PN spectrum. For compensation of the common phase error (CPE), the maximum likelihood estimation of the CPE is shown to be equal to a determinant criterion optimization. For practical implementation an estimator with reduced complexity is found, for which an upper bound on the error is found. Using this bound the resulting PN spectrum after compensation can be found, which enables the derivation of the effect of the residual PN. The performance of the compensation scheme in an additive white Gaussian noise (AWGN) environment and resulting bit-error-rate (BER) are shown using results from simulations

Conflict-related sexual violence and international law: a critical assessment of the preventing sexual violence initiative

My research addresses how the international community goes about trying to prevent conflict-related sexual violence. With much of the focus on international law, I examine the Preventing Sexual Violence Initiative, put forth by the UK Government in 2012. I assess the legalistic approach to prevention and the progress that has been made over the last few decades

On large-scale diagonalization techniques for the Anderson model of localization

We propose efficient preconditioning algorithms for an eigenvalue problem arising in quantum physics, namely the computation of a few interior eigenvalues and their associated eigenvectors for large-scale sparse real and symmetric indefinite matrices of the Anderson model of localization. We compare the Lanczos algorithm in the 1987 implementation by Cullum and Willoughby with the shift-and-invert techniques in the implicitly restarted Lanczos method and in the Jacobi–Davidson method. Our preconditioning approaches for the shift-and-invert symmetric indefinite linear system are based on maximum weighted matchings and algebraic multilevel incomplete LDLT factorizations. These techniques can be seen as a complement to the alternative idea of using more complete pivoting techniques for the highly ill-conditioned symmetric indefinite Anderson matrices. We demonstrate the effectiveness and the numerical accuracy of these algorithms. Our numerical examples reveal that recent algebraic multilevel preconditioning solvers can accelerate the computation of a large-scale eigenvalue problem corresponding to the Anderson model of localization by several orders of magnitude

Axially linear slopes of composition for “delta” crystals

“Delta” crystals are solid solutions of miscible materials with large lattice parameter differences which contain high concentration gradients in one direction (parallel to a lattice plane strongly diffracting X-rays). The system GaSb-InSb has been chosen as suitable for study. By means of a “gradient projection method”, the growth of nearly linear composition profiles with relatively steep slopes of the lattice parameter (up to (Δa/ ) / Δz = 8.3% cm-1), adjustable by the temperature gradient, have been performed. However, the grown ingots were not monocrystalline due to the use of too high a growth rate

Sporopollenin, a natural copolymer, is robust under high hydrostatic pressure

Lycopodium sporopollenin, a natural copolymer, shows exceptional stability under high hydrostatic pressures (10 GPa) as determined by in situ high pressure synchrotron source FTIR spectroscopy. This stability is evaluated in terms of the component compounds of the sporopollenin: p-coumaric acid, phloretic acid, ferulic acid, and palmitic and sebacic acids, which represent the additional n-acid and ndiacid components. This high stability is attributed to interactions between these components, rather than the exceptional stability of any one molecular component. We propose a biomimetic solution for the creation of polymer materials that can withstand high pressures for a multitude of uses in aeronautics, vascular autografts, ballistics and light-weight protective materials