AKLT Models with Quantum Spin Glass Ground States

We study AKLT models on locally tree-like lattices of fixed connectivity and find that they exhibit a variety of ground states depending upon the spin, coordination and global (graph) topology. We find a) quantum paramagnetic or valence bond solid ground states, b) critical and ordered N\'eel states on bipartite infinite Cayley trees and c) critical and ordered quantum vector spin glass states on random graphs of fixed connectivity. We argue, in consonance with a previous analysis, that all phases are characterized by gaps to local excitations. The spin glass states we report arise from random long ranged loops which frustrate N\'eel ordering despite the lack of randomness in the coupling strengths.Comment: 10 pages, 1 figur

Kernel-based independence tests for causal structure learning on functional data

Measurements of systems taken along a continuous functional dimension, such as time or space, are ubiquitous in many fields, from the physical and biological sciences to economics and engineering. Such measurements can be viewed as realisations of an underlying smooth process sampled over the continuum. However, traditional methods for independence testing and causal learning are not directly applicable to such data, as they do not take into account the dependence along the functional dimension. By using specifically designed kernels, we introduce statistical tests for bivariate, joint, and conditional independence for functional variables. Our method not only extends the applicability to functional data of the Hilbert–Schmidt independence criterion (hsic) and its d-variate version (d-hsic), but also allows us to introduce a test for conditional independence by defining a novel statistic for the conditional permutation test (cpt) based on the Hilbert–Schmidt conditional independence criterion (hscic), with optimised regularisation strength estimated through an evaluation rejection rate. Our empirical results of the size and power of these tests on synthetic functional data show good performance, and we then exemplify their application to several constraint- and regression-based causal structure learning problems, including both synthetic examples and real socioeconomic data

Effect of resistant and susceptible soybean cultivars on the attraction of egg parasitoids under field conditions.

Resumo 0162

The Valence Bond Glass phase

We show that a new glassy phase can emerge in presence of strong magnetic frustration and quantum fluctuations. It is a Valence Bond Glass. We study its properties solving the Hubbard-Heisenberg model on a Bethe lattice within the large $N$ limit introduced by Affleck and Marston. We work out the phase diagram that contains Fermi liquid, dimer and valence bond glass phases. This new glassy phase has no electronic or spin gap (although a pseudo-gap is observed), it is characterized by long-range critical valence bond correlations and is not related to any magnetic ordering. As a consequence it is quite different from both valence bond crystals and spin glasses

Influence of visual cues on host-searching and learning behaviour of the egg parasitoids Telenomus podisi and Trissolcus basalis.

Insect parasitoids use a variety of chemical and physical cues when foraging for hosts and food. Parasitoids can learn cues that lead themto the hosts, thus contributing to better foraging.One of the cues that in?uence host-searching behaviour could be colour. In this study, we investigated the ability of females of the parasitoid wasps Telenomus podisi Ashmead and Trissolcus basalisWollaston (both Hymenoptera: Scelionidae) to respond to colours and to associate the presence of hosts ? eggs of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) ? with coloured substrates after training (associative learning). Two sets of experiments were conducted: in one the innate preference for substrate colours was examined, in the other associative learning of substrate colour and host presence was tested in multiple-choice and dual-choice experiments. In the associative learning experiments, Te. podisi and Tr. basalis were trained to respond to differently coloured substrates containing hosts in two sessions of 2 h each, with 1-h intervals. In multiple-choice experiments, the wasps displayed innate preference for yellow substrates over green, brown, black, or white ones. Even after being trained on substrates of different colours, both parasitoids continued to show preference for yellow substrates. The response to the colours of substrates of both parasitoids was related with the orientation to the plant foliage during the search for hosts

Effect of resistant and susceptible soybean cultivars on the nymphal development, fecundity and mortality of Euschistus heros (Hemiptera:pentatomidae).

The association of resistant varieties and biological control has great interest and potential to be used for pest management. lhe aims of this work were to evaluate the effect of cultivars Silvânia (susceptible to stink bug attack), Dowling e IACI00 (resistant) on E. heras nymph development and to investigate the influence of the flavonoids on the resistance [1]. Nymphs of stink bug were placed in Petri dishes on a diet of soybean pods and observed daily. After adult emergence, they were weight and then put in pairs for mating. lhe nymph mortality, the adult longevity, fecundity and the eggs fertility were evaluated for each cultivar. To quantify the flavonoid compounds, extracts of immature seeds (cv Silvânia and Dowling) undamaged and damage by herbivory, were analysed using high performance liquid chromatography (HPLC). lhe nymphs reared on cv Dowling did not complete their biological cycle. Survivorship curves of immatures in cv. Sylvania and IAClOO, analysed by Kaplan-Meier Survival Distribution, did not show significant difference. lhe medium weight of adults on others cultivars was not different. lhe medium male longevity on cv IAClOOwas 11.0 days, while on cv Silvânia was 35.8 days; for females was 13.4 days on cv IAClOOand 40.6 days on cv Silvânia. lhe female fecundity (105.7 eggs/female) and egg fertility (66.3 nymphs) on cv Silvânia were higher than on cv IACI00 (10.2 eggs/female e 5.8 nymphs). Total amount of flavonoids compounds was higher in cv Silvânia than in cv Dowling, but did not differ when compared between herbivory damage and undamaged plants in the same cultivar. These results suggest that the cv IACI00 and Dowling present direct defense (constitutive) against E. heras, and that the herbivory damage did not induce flavonoids production