Cues for shelter use in a phytophagous insect

Many insects spend a large proportion of their life inactive, often hiding in shelters. The presence of shelters may, therefore, influence where insects feed. This study examines stimuli affecting the use of shelters by adults of the pine weevil, Hylobius abietis (L.) (Coleoptera, Curculionidae). This species is an economically important forest pest in Europe since the adults feed on the stem bark of newly planted conifer seedlings. When there are hiding or burrowing places present in close proximity to a seedling, pine weevils may hide there and repeatedly return to feed on the same seedling. Experiments were conducted in a laboratory arena with above-ground or below-ground shelters and in the presence or absence of wind. Pine weevils were highly attracted to shelters both above and below ground. Weevils in shelters were often observed assuming a characteristic "resting" posture. Experiments with opaque and transparent shelters showed that visual stimuli are used for orientation towards shelters and also increase the probability of an individual remaining in a shelter. The presence of wind increased the weevils' propensity to use shelters both above and below ground. The present study indicates that shelters have a major influence on the behavior of the pine weevil and possible implications of the results are discussed

Higher loops, integrability and the near BMN limit

In this note we consider higher-loop contributions to the planar dilatation operator of N=4 SYM in the su(2) subsector of two complex scalar fields. We investigate the constraints on the form of this object due to interactions of two excitations in the BMN limit. We then consider two scenarios to uniquely fix some higher-loop contributions: (i) Higher-loop integrability fixes the dilatation generator up to at least four-loops. Among other results, this allows to conjecture an all-loop expression for the energy in the near BMN limit. (ii) The near plane-wave limit of string theory and the BMN correspondence fix the dilatation generator up to three-loops. We comment on the difference between both scenarios.Comment: 6 page

Journal Staff

Water and supercritical carbon dioxide have different wetting angles to a glass surface, where water has a lower angle. In a microfluidic channel, the lower wetting angle draws the water to surround the supercritical carbon dioxide and the supercritical carbon dioxide therefore easily form droplets or segments if the flow rate is low. In this study, the flow of supercritical carbon dioxide and water has been studied in a microfluidic system with a double Y-channel. The micro channels have been built in borofloat glass to withstand high mechanical and chemical forces, still enabling in situ characterization. The aim has been to analyze flow changes in the water and supercritical carbon dioxide in structured channels with and without surface modification.             The result shows that the flow regime of supercritical carbon dioxide and water can be controlled by changing flow rates, adding walls, or coating a channel as well as any combination of these three. If adding a large enough wall in a channel, the flow will be segmented only in half the channel at moderate flow rates from both sources, and parallel if the flow rate of supercritical carbon dioxide is high enough. A non-polar coating of half a channel will make the supercritical carbon dioxide flow along the coated side and supercritical carbon dioxide can by that way be forced to only take one of the outlets. However, still water exit at both outlets

The su(2|3) Dynamic Spin Chain

The complete one-loop, planar dilatation operator of the N=4 superconformal gauge theory was recently derived and shown to be integrable. Here, we present further compelling evidence for a generalisation of this integrable structure to higher orders of the coupling constant. For that we consider the su(2|3) subsector and investigate the restrictions imposed on the spin chain Hamiltonian by the symmetry algebra. This allows us to uniquely fix the energy shifts up to the three-loop level and thus prove the correctness of a conjecture in hep-th/0303060. A novel aspect of this spin chain model is that the higher-loop Hamiltonian, as for N=4 SYM in general, does not preserve the number of spin sites. Yet this dynamic spin chain appears to be integrable.Comment: 34 pages, 5 figures, v2: additional coefficient at three loops explained, discussion of integrability enhanced, figures adde

On Yangian Symmetry in Planar N=4 SYM

Planar N=4 supersymmetric Yang-Mills theory appears to be perturbatively integrable. This work reviews integrability in terms of a Yangian algebra and compares the application to the problems of anomalous dimensions and scattering amplitudes.Comment: 24 pages, To Lev Lipatov on the occasion of his 70th birthday, v2: references and typos corrected, v3: no changes, references updated, published in "Subtleties in Quantum Field Theory", pp. 175, ed: D. Diakonov and "Gribov-80 Memorial Volume: Quantum Chromodynamics and Beyond", pp. 413, ed: Yu. Dokshitzer, P. L\'evai, J. Ny\'ir

The Analytic Bethe Ansatz for a Chain with Centrally Extended su(2|2) Symmetry

We investigate the integrable structure of spin chain models with centrally extended su(2|2) and psu(2,2|4) symmetry. These chains have their origin in the planar AdS/CFT correspondence, but they also contain the one-dimensional Hubbard model as a special case. We begin with an overview of the representation theory of centrally extended su(2|2). These results are applied in the construction and investigation of an interesting S-matrix with su(2|2) symmetry. In particular, they enable a remarkably simple proof of the Yang-Baxter relation. We also show the equivalence of the S-matrix to Shastry's R-matrix and thus uncover a hidden supersymmetry in the integrable structure of the Hubbard model. We then construct eigenvalues of the corresponding transfer matrix in order to formulate an analytic Bethe ansatz. Finally, the form of transfer matrix eigenvalues for models with psu(2,2|4) symmetry is sketched.Comment: 66 pages, v2: minor changes, references added, to appear in JSTA

Computing the Tutte Polynomial of a Matroid from its Lattice of Cyclic Flats

We show how the Tutte polynomial of a matroid $M$ can be computed from its condensed configuration, which is a statistic of its lattice of cyclic flats. The results imply that the Tutte polynomial of $M$ is already determined by the abstract lattice of its cyclic flats together with their cardinalities and ranks. They furthermore generalize a similiar statement for perfect matroid designs due to Mphako and help to understand families of matroids with identical Tutte polynomial as constructed by Ken Shoda.Comment: New version published in: Electronic Journal Of Combinatorics Volume 21, Issue 3 (2014) http://www.combinatorics.org/ojs/index.php/eljc/article/view/v21i3p4