Emergence of a Chern-insulating state from a semi-Dirac dispersion

A Chern insulator (quantum anomalous Hall insulator) phase is demonstrated to exist in a typical semi-Dirac system, the TiO2/VO2 heterostructure. By combining first-principles calculations with Wannier-based tight-binding model, we calculate the Berry curvature distribution, finding a Chern number of -2 for the valence bands, and demonstrate the existence of gapless chiral edge states, ensuring quantization of the Hall conductivity to 2e^2/h. A new semi-Dirac model, where each semi-Dirac cone is formed by merging three conventional Dirac points, is proposed to reveal how the nontrivial topology with finite Chern number is compatible with a semi-Dirac electronic spectrum.Comment: 12 pages, 3 figure

Why Does Spousal Education Matter for Earnings? Assortative Mating or Cross-productivity

In interpreting the positive relationship between spousal education and one's earnings, economists have two major hypotheses: cross-productivity between couples and assortative mating. However, no prior empirical study has been able to separate the two effects. This paper empirically disentangles the two effects by using twins data that we collected from urban China. We have two major innovations: we use twins data to control for the unobserved mating effect in our estimations, and we estimate both current and wedding-time earnings equations. Arguably, the cross-productivity effect takes time to be realized and thus is relatively unimportant at the time of the wedding. Any effect of spousal education on wedding-time earnings should more likely be the mating effect. We find that both cross-productivity and mating are important in explaining the current earnings. Although the mating effect exists for both husbands and wives, the cross-productivity effect only runs from Chinese husbands to wives. We further show that the cross-productivity effect is realized by increasing the hourly wage rate rather than working hours.

Amygdalin protects apoptosis of retinal ganglionic cells in glaucoma rats by regulating the expressions of anti- and pro-apoptotic proteins

Purpose: To evaluate the protective effect of amygdalin against glaucoma.Methods: Glaucoma was induced in rats via ischemia/reperfusion. The rats were treated with amygdalin (1 mg/kg) intraperitoneally (ip) for 5 weeks. Intra-ocular pressure (IOP), viability of retinal ganglion cell (RGCs) and histopathological changes in the retinal tissue of the glaucoma rats were determined. The expression levels of inflammatory cytokines and expressions of apoptotic factors were assessed in retinal tissues of all groups.Results: Intra-ocular pressure was reduced in amygdalin-treated group, when compared with the glaucoma group (p < 0.05). Moreover, the viability and thickness of RGCs in the amygdalin-treated group were enhanced, relative to untreated glaucoma rats. There was decrease in retinal cytokinelevels in amygdalin-treated group, when compared with untreated glaucoma rats. Amygdalin treatment ameliorated altered expressions of apoptosis proteins in the retinal tissue of ischemia/reperfusioninduced glaucoma rats.Conclusion: Amygdalin has a protective effect against ischemia/reperfusion-induced glaucoma in rats. Thus, it has a potential for use in the clinical management of glaucoma. Keywords: Glaucoma, Amygdalin, Cytokines, Ischemia/reperfusion, Apoptosi

Online Robot Introspection via Wrench-based Action Grammars

Robotic failure is all too common in unstructured robot tasks. Despite well-designed controllers, robots often fail due to unexpected events. How do robots measure unexpected events? Many do not. Most robots are driven by the sense-plan act paradigm, however more recently robots are undergoing a sense-plan-act-verify paradigm. In this work, we present a principled methodology to bootstrap online robot introspection for contact tasks. In effect, we are trying to enable the robot to answer the question: what did I do? Is my behavior as expected or not? To this end, we analyze noisy wrench data and postulate that the latter inherently contains patterns that can be effectively represented by a vocabulary. The vocabulary is generated by segmenting and encoding the data. When the wrench information represents a sequence of sub-tasks, we can think of the vocabulary forming a sentence (set of words with grammar rules) for a given sub-task; allowing the latter to be uniquely represented. The grammar, which can also include unexpected events, was classified in offline and online scenarios as well as for simulated and real robot experiments. Multiclass Support Vector Machines (SVMs) were used offline, while online probabilistic SVMs were are used to give temporal confidence to the introspection result. The contribution of our work is the presentation of a generalizable online semantic scheme that enables a robot to understand its high-level state whether nominal or abnormal. It is shown to work in offline and online scenarios for a particularly challenging contact task: snap assemblies. We perform the snap assembly in one-arm simulated and real one-arm experiments and a simulated two-arm experiment. This verification mechanism can be used by high-level planners or reasoning systems to enable intelligent failure recovery or determine the next most optima manipulation skill to be used.Comment: arXiv admin note: substantial text overlap with arXiv:1609.0494

Coevolution of synchronous activity and connectivity in coupled chaotic oscillators

We investigate the coevolution dynamics of node activities and coupling strengths in coupled chaotic oscillators via a simple threshold adaptive scheme. The coupling strength is synchronous activity regulated, which in turn is able to boost the synchronization remarkably. In the case of weak coupling, the globally coupled oscillators present a highly clustered functional connectivity with a power-law distribution in the tail with γ≃3.1, while for strong coupling, they self-organize into a network with a heterogeneously rich connectivity at the onset of synchronization but exhibit rather sparse structure to maintain the synchronization in noisy environment. The relevance of the results is briefly discussed