Electrochemical control of quantum interference in anthraquinone-based molecular switches

Using first-principles calculations we analyze the electronic transport properties of a recently proposed anthraquinone based electrochemical switch. Robust conductance on/off ratios of several orders of magnitude are observed due to destructive quantum interference present in the anthraquinone, but absent in the hydroquinone molecular bridge. A simple explanation of the interference effect is achieved by transforming the frontier molecular orbitals into localized molecular orbitals thereby obtaining a minimal tight-binding model describing the transport in the relevant energy range in terms of hopping via the localized orbitals. The topology of the tight-binding model, which is dictated by the symmetries of the molecular orbitals, determines the amount of quantum interference.Comment: 6 pages, 6 figure

The Yoneda algebra of a graded Ore extension

Let A be a connected-graded algebra with trivial module k, and let B be a graded Ore extension of A. We relate the structure of the Yoneda algebra E(A) := Ext_A(k,k) to E(B). Cassidy and Shelton have shown that when A satisfies their K_2 property, B will also be K_2. We prove the converse of this result.Comment: 9 page

Fruit thinning in organic apple growing with optimized timing and combination strategies including (new) natural spray products and mechanical rope-devices

The aim of our study was to find new thinning methods for organic apple production able to fulfil the standards of Bio-Suisse, the main label organisation of the organic food sector in Switzerland. The 14 trials reported were carried out during flowering period in 2003 and 2004 on the cultivars Pinova, Gala, Maigold, Elstar, Golden Delicious and Otava at different sites. The results confirm the good efficiency of mechanical thinning with the rope thinner and the thinning potential of vinasse, a by-product of molasses. Different vinasse products were tested (K-Vinasse, light-vinasse, N-Vinasse) and it was observed that those containing less nitrogen had a minor thinning effect. To avoid phytotoxicity on leaves, the concentration of N-Vinasse should not exceed 10 %. It seems that for Gala higher concentrations are needed, 7.5-10%, whereas with Maigold the efficacy of N-Vinasse was the same with the 2.5 % concentration as with 5 % and 10 %. On the other hand, partly good results were obtained when N-Vinasse was over-concentrated to 12 %, applied at warm weather and rinsed with clear water 4-6 hours later to avoid the phyto-toxic effect (“burn & rinse” method). Corn Oil, a commercial product from New Zealand, gave encouraging results. Lime sul-phur didn’t effectuate a significantly better thinning effect. The best method tested (fruit set reduction by 44 % and 26 % higher flower bud set next year) was achieved with a combination of rope thinner and N-Vinasse: rope thinner to thin the peripheral branches and to exert a physiological stress; and N-Vinasse to thin the inner parts of the canopy that the ropes can’t reach. Other tested products did not show satisfying effects. Trials also confirmed the importance of applying these thinning agents at least two times, at the appropriate phenological stage of flowering period (F,) F2 (full bloom) and G (= F2 of the one-year old shoots). Hitting also the flowers of the one-year old shoots is important to break bi-annual bearing. Pollen tube growth was assessed by fluorescence microscopy. Almost complete inhibition of pollen tube germina-tion was observed with Lime Sulphur and over-concentrated N-Vinasse (12 %) whereas with N-Vinasse at 5 % inhibition was 50 % less compared to untreated styles. Some contradictory results between different trials we ascribe to the air temperature during and after the treatments. It seems that treatments with N-Vinasse should be carried out at warm and sunny days above 16, better 18-20 deg. C. to maximize phytotoxicity on the styles; whereas we recommend to apply the rope thinner during periods of cold and clouded weather to maximize the thinning effect due to physiological stress and shortage of assimilates to the fruitlets. Concrete practical recommendations are given

Trajectory similarity analysis in movement parameter space

This paper introduces a similarity analysis method for moving object trajectories. The proposed method assesses the similarity between a set of trajectories in a multidimensional space, whose dimensions are formed by different movement parameters (e.g. position, speed, acceleration, direction), plus time. We investigate the applicability of the proposed method in finding relative movement patterns such as coincidence and concurrence in the movement of North Atlantic hurricanes

Exploring movement – similarity analysis of moving objects

Extracting knowledge about the movement of different types of mobile agents (e.g. human, animals, vehicles) and dynamic phenomena (e.g. hurricanes) requires new exploratory data analysis methods for massive movement datasets. Different types of moving objects share similarities but also express differences in terms of their dynamic behavior and the nature of their movement. Extracting such similarities can significantly contribute to the prediction, modeling and simulation dynamic phenomena. Therefore, with the development of a quantitative methodology this research intends to investigate and explore similarities in the dynamics of moving objects by using methods of GIScience in knowledge discovery. This paper presents a summary of the ongoing Ph.D. research project

Plumage convergence in Picoides woodpeckers based on a molecular phylogeny, with emphasis on convergence in downy and hairy woodpeckers

Adult and juvenile plumage characters were traced onto a well-resolved molecular based phylogeny for Picoides woodpeckers, and a simple phylogenetic test of homology, parallelism, and convergence of plumage characters was performed. Reconstruction of ancestral character states revealed multiple events of independent evolution of derived character states in most characters studied, and a concentrated changes test revealed that some plumage characters evolved in association with habitat type. For example, there was a statistically significant association between loss of dorsal barring and use of densely vegetated habitats among Picoides species. Two analyses indicated that convergence, as opposed to parallel evolution or shared ancestry, underlies the similarity in plumage patterns between the Downy (Picoides pubescens) and Hairy (P. villosus) Woodpeckers. Possible causal explanations for convergence in plumage patterns may include mimicry and interspecific territoriality