1,939 research outputs found

    Exact results for the star lattice chiral spin liquid

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    We examine the star lattice Kitaev model whose ground state is a a chiral spin liquid. We fermionize the model such that the fermionic vacua are toric code states on an effective Kagome lattice. This implies that the Abelian phase of the system is inherited from the fermionic vacua and that time reversal symmetry is spontaneously broken at the level of the vacuum. In terms of these fermions we derive the Bloch-matrix Hamiltonians for the vortex free sector and its time reversed counterpart and illuminate the relationships between the sectors. The phase diagram for the model is shown to be a sphere in the space of coupling parameters around the triangles of the lattices. The abelian phase lies inside the sphere and the critical boundary between topologically distinct Abelian and non-Abelian phases lies on the surface. Outside the sphere the system is generically gapped except in the planes where the coupling parameters are zero. These cases correspond to bipartite lattice structures and the dispersion relations are similar to that of the original Kitaev honeycomb model. In a further analysis we demonstrate the three-fold non-Abelian groundstate degeneracy on a torus by explicit calculation.Comment: 7 pages, 8 figure

    Are high strivers for justice more unjust when they react to a victim? Further evidence on the effects of the belief in a just world, of the innocence of the victim and of the persistence of suffering on secondary victimization

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    This research aims to further explore the effects of Belief in a Just World (BJW), victim’s innocence and persistence of suffering on secondary victimization. Previous studies showed that an innocent victim whose suffering is more persistent is more secondarily victimized by high BJW participants than by low BJW participants (Correia & Vala, 2003). This study intends to replicate this finding and to overcome methodological limitations of these previous studies. Participants were 266 undergraduate students. The design was between-subjects 2 BJW (high, low) X 2 innocence of the victim (innocent, non-innocent) X 2 persistence of the suffering of the victim (more persistent, less persistent). The results supported partially the predictions. Theoretical as well as social implications of these findings are discussed

    Optical measurements of electrophoretic suspension kinetics

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    Electrophoretic deposition (EPD) was originally used for formation of coatings, e. g. in the automotive industry. Recently EPD is successfully utili zed for thin film preparation with an app lication in the optics and electronics. This paper investigates the process of the suspension formation and aggregation by ultraviolet and visible spectroscopy (UV- VIS) spectroscopy and Dynamic Light Scattering (DLS) methods. The suspensions were formed by a precipitation of solution of poly[2-methoxy-5-(3 ′ ,7 ′ -dimethyloctyloxy)-1,4-phenylenevinylene] in toluene using acetonitrile as a precipitator. It could be concluded that the progressive suspension particle growth observed by DLS affects regularly the first derivative of the UV-VIS spectra. By a comparison of the results obtained by both methods it could be seen that UV-VIS spectroscopy combined with the spline method could be successfully used for an estimation of electrophoretic suspensions

    Globally Optimal Quantum Control

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    Optimization methods for constrained quantum control problems power quantum technologies. Such control problems are notoriously difficult because they are non-convex and plagued with local extrema. Current optimization methods must be repeated many times to find good solutions, each time requiring many simulations of the system. Here we present Quantum Control via Polynomial Optimization (QCPOp), a method that eliminates this problem by directly finding globally optimal solutions. This remarkable ability is due to global optimization methods recently developed for polynomial functions. We demonstrate the tremendous improvement over current state-of-the-art methods using a number of non-trivial examples. Global optimization also allows QCPOp to find the simplest control solutions. Since QCPOp is able to reveal the optimum performance of quantum control with high confidence, we expect that it will not only enhance the utility of such control but provide a key tool for determining the limits of quantum technologies.Comment: Significantly updated content with many new cool examples (10 pages and 6 figures

    Relative vibrotactile spatial acuity of the torso

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    While tactile acuity for pressure has been extensively investigated, far less is known about acuity for vibrotactile stimulation. Vibrotactile acuity is important however, as such stimulation is used in many applications, including sensory substitution devices. We tested discrimination of vibrotactile stimulation from eccentric rotating mass motors with in-plane vibration. In 3 experiments, we tested gradually decreasing center-to-center (c/c) distances from 30 mm (experiment 1) to 13 mm (experiment 3). Observers judged whether a second vibrating stimulator (‘tactor’) was to the left or right or in the same place as a first one that came on 250 ms before the onset of the second (with a 50-ms inter-stimulus interval). The results show that while accuracy tends to decrease the closer the tactors are, discrimination accuracy is still well above chance for the smallest distance, which places the threshold for vibrotactile stimulation well below 13 mm, which is lower than recent estimates. The results cast new light on vibrotactile sensitivity and can furthermore be of use in the design of devices that convey information through vibrotactile stimulation.Peer Reviewe

    Histopathological features of organs in a rat model of mamamry carcinogenesis: a reference database

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    Mammary tumors’ development was induced through the intraperioneal administration of the carcinogen N-methyl-N-nitrosourea (MNU). Animals from group control were injected with the vehicle (saline solution). Animals were sacrificed at 25 weeks-old and the organs were histopathologically evaluated. A higher number of lesions was observed in the organs of animals from group MNU. The animals from group control did not present any lesion in lymph nodes. Independently of the experimental group, the internal organs presented hemodynamic alterations, degenerative and inflammatory changes. Hemodynamic changes may be consequence of euthanasia method. As expected, the higher number and the higher grade of the lesions in group MNU were due to the carcinogen administration.info:eu-repo/semantics/publishedVersio

    How fair is economic inequality? Belief in a just world and the legitimation of economic disparities in 27 European countries

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    This article aims to examine the role of Belief in a Just World (BJW) in the legitimation of economic inequality. Using data from 27 European countries (N=47,086), we conducted multilevel analyses and found that BJW positively predicted the legitimation of economic inequality, measured by three indicators: the perceived fairness of the overall wealth inequality, and the fairness of the earnings made by the Top 10% and the Bottom 10% of society. These results persisted after controlling for individual- and country-level variables. Moreover, the BJW effect was stronger on the legitimation of the Bottom 10% incomes, compared to the legitimation of the Top 10%. We also found that economic inequality at the country-level reduced the BJW effect on legitimation of inequality. Finally, BJW displayed a negative indirect effect on support for redistribution, via the legitimation of economic inequalities.info:eu-repo/semantics/acceptedVersio

    A scalable quantum computer with an ultranarrow optical transition of ultracold neutral atoms in an optical lattice

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    We propose a new quantum-computing scheme using ultracold neutral ytterbium atoms in an optical lattice. The nuclear Zeeman sublevels define a qubit. This choice avoids the natural phase evolution due to the magnetic dipole interaction between qubits. The Zeeman sublevels with large magnetic moments in the long-lived metastable state are also exploited to address individual atoms and to construct a controlled-multiqubit gate. Estimated parameters required for this scheme show that this proposal is scalable and experimentally feasible.Comment: 6 pages, 6 figure

    Evaluation of renal injury caused by acute volume replacement with hydroxyethyl starch 130/0.4 or Ringer's lactate solution in pigs

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    This work aimed to evaluate the effects on renal tissue integrity after hydroxyethyl starch (HES) 130/0.4 and Ringer’s lactate (RL) administration in pigs under general anesthesia after acute bleeding. A total of 30 mL/kg of blood were passively removed from the femoral artery in two groups of Large White pigs, under total intravenous anesthesia with propofol and remifentanil. After bleeding, Group 1 (n =11) received RL solution (25 mL/kg) and Group 2 (n = 11) received HES 130/0.4 solution (20 mL/kg). Additionally, Group 3 (n = 6) was not submitted to bleeding or volume replacement. Pigs were euthanized and kidneys were processed for histopathological and immunohistochemical analyses. Minimal to moderate glomerular, tubular, and interstitial changes, as well as papillary necrosis, were observed in all experimental groups. Pre-apoptosis and apoptosis indicators were higher in pigs that received HES 130/0.4, indicating a higher renal insult. Both HES 130/0.4 and RL administration may cause renal injury, although renal injury may be more significant in pigs receiving HES 13/0.4. Results also suggest that total intravenous anesthesia with propofol and remifentanil may cause renal injury, and this effect can be dose related.info:eu-repo/semantics/publishedVersio
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