Dynamic Response of a Cylindrical Shell Segment Subjected to an Arbitrary Loading

Dynamic response analysis for underground cylindrical shell segments subjected to blast loadin

Forces and conductances in a single-molecule bipyridine junction

Inspired by recent measurements of forces and conductances of bipyridine nano-junctions, we have performed density functional theory calculations of structure and electron transport in a bipyridine molecule attached between gold electrodes for seven different contact geometries. The calculations show that both the bonding force and the conductance are sensitive to the surface structure, and that both properties are in good agreement with experiment for contact geometries characterized by intermediate coordination of the metal atoms corresponding to a stepped surface. The conductance is mediated by the lowest unoccupied molecular orbital, which can be illustrated by a quantitative comparison with a one-level model. Implications for the interpretation of the experimentally determined force and conductance distributions are discussed

Axisymmetric Dynamic Response of Spherical and Cylindrical Shells

Axisymmetric dynamic response of spherical and cylindrical shell

Towards Grower-friendly Apple Crop Thinning by Tree Shading

Light management with shading nets, which reduce sunlight by 74%, might be an alternative to chemicals commonly used for thinning on apple trees. To study the effect of shading on crop load and fruit quality, trials were conducted in field experiments with the cultivars Golden Delicious and Elstar in 2006. Trees were either covered 25 days after full bloom (DAFB) with a net during three days, or until the peak of fruit fall, observed after seven days shading. Ideal time length for optimal crop yield was seven days shading for Elstar and three days shading for Golden Delicious. Alternate bearing could be decreased as flower initiation counts the following year showed. In both experiments, inner quality of fruit such as sugar and firmness showed good values at optimal shading duration compared with chemical + hand thinning. In 2007, a second field trial was conducted with cultivars Golden Delicious and Topaz to study the time period for shading in further detail. Shading was done for three days at 19, 26 and 33 DAFB using two net types (three- and two-meter-net width, covering the trees entirely or only down to 50 cm above ground). For Golden Delicious, shading after 19 and 26 days reduced fruits per 100 flower cluster to the same extent as with chemical + hand thinning. There was no difference between the two net types. For Topaz, shading after 19 days showed the best results. Regarding inner quality of both cultivars, only sugar content for Golden Delicious could be significantly improved after 19 and 26 days shading. Further analyses are still under way (e.g. for acidity). This study is part of an effort for increasing European consumption with fruit from sustainable production systems, the ISAFRUIT-EU-project

The Emergence of Insight in Problem Solving

This paper relates the notion of insight in problem solving to the current debate concerning epistemological and ontological emergence. The psychological school that stresses the relevance of insight for solving certain types of problems has been Gestalt theory. In classical Gestaltist writings, however, there is not much information about the question of whether or not insights are wholes with emergent properties. It is only in the more recent literature that this question is formulated. The present paper provides examples of insight problems (section I). Then it shows how insight was characterized in Gestalt theoretical writings, in particular by K. Duncker (II), and how this relates to the philosophical debate on emergence (III). After presenting two stances in research on problem solving that resemble the positions arguing for epistemological and ontological emergence (IV), I conclude with suggesting an alternative by complementing the basic part-whole framework with bidirectional processes found in perceptual reversals of ambiguous figures (V). In so doing I suggest to understand insight as ‘intersight,’ which is not an emergent whole, but a hinge or switch that mediates between two or more part-whole structures (here: problem and solution).This paper relates the notion of insight in problem solving to the current debate concerning epistemological and ontological emergence. The psychological school that stresses the relevance of insight for solving certain types of problems has been Gestalt theory. In classical Gestaltist writings, however, there is not much information about the question of whether or not insights are wholes with emergent properties. It is only in the more recent literature that this question is formulated. The present paper provides examples of insight problems (section I). Then it shows how insight was characterized in Gestalt theoretical writings, in particular by K. Duncker (II), and how this relates to the philosophical debate on emergence (III). After presenting two stances in research on problem solving that resemble the positions arguing for epistemological and ontological emergence (IV), I conclude with suggesting an alternative by complementing the basic part-whole framework with bidirectional processes found in perceptual reversals of ambiguous figures (V). In so doing I suggest to understand insight as ‘intersight,’ which is not an emergent whole, but a hinge or switch that mediates between two or more part-whole structures (here: problem and solution)

Faddeev equations with three-nucleon force in momentum space

Modified Faddeev equations that allow the inclusion of irreducible three-body forces in addition to two-body interactions are formulated and the technical apparatus for their solution in momentum space is described. Results for the triton binding energy are obtained with realistic two-nucleon interactions and the Tucson-Melbourne two-pion exchange three-nucleon force and compared with previous calculations. Excellent agreement with the results of other groups is found confirming that the accuracy of present-day techniques for handling three-nucleon forces is very high indeed

Josephson current through a quantum dot coupled to a molecular magnet

Josephson currents are carried by sharp Andreev states within the superconducting energy gap. We theoretically study the electronic transport of a magnetically tunable nanoscale junction consisting of a quantum dot connected to two superconducting leads and coupled to the spin of a molecular magnet. The exchange interaction between the molecular magnet and the quantum dot modifies the Andreev states due to a spin-dependent renormalization of the quantum dot's energy level and the induction of spin-flips. A magnetic field applied to the central region of the quantum dot and the molecular magnet further tunes the Josephson current and starts a precession of the molecular magnet's spin. We use a non-equilibrium Green's function approach to evaluate the transport properties of the junction. Our calculations reveal that the energy level of the dot, the magnetic field and the exchange interaction between the molecular magnet and the electrons occupying the energy level of the quantum dot can trigger transitions from a 0 to a $\pi$ state of the Josephson junction. The redistribution of the occupied states induced by the magnetic field strongly modifies the current-phase relation. The critical current exhibits a sharp increase as a function of either the energy level of the dot, the magnetic field or the exchange interaction.Comment: 10 pages, 7 figure

Relativistic calculation of the triton binding energy and its implications

First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic OBE models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.Comment: 5 pages, RevTeX 3.0, 1 figure (uses epsfig.sty