Phase diagrams of a classical two-dimensional Heisenberg antiferromagnet with single-ion anisotropy

A classical variant of the two-dimensional anisotropic Heisenberg model reproducing inelastic neutron scattering experiments on La_5 Ca_9 Cu_24 O_41 [M. Matsuda et al., Phys.Rev. B 68, 060406(R) (2003)] is analysed using mostly Monte Carlo techniques. Phase diagrams with external fields parallel and perpendicular to the easy axis of the anisotropic interactions are determined, including antiferromagnetic and spin-flop phases. Mobile spinless defects, or holes, are found to form stripes which bunch, debunch and break up at a phase transition. A parallel field can lead to a spin-flop phase.Comment: 9 pages, 9 figures; final version as accepted by Phys. Rev. B (Fig. 5 replaced, added remarks in Secs. I, III, and V

Overcoming the roadblocks to cardiac cell therapy using tissue engineering

Transplantations of various stem cells or their progeny have repeatedly improved cardiac performance in animal models of myocardial injury; however, the benefits observed in clinical trials have been generally less consistent. Some of the recognized challenges are poor engraftment of implanted cells and, in the case of human cardiomyocytes, functional immaturity and lack of electrical integration, leading to limited contribution to the heart’s contractile activity and increased arrhythmogenic risks. Advances in tissue and genetic engineering techniques are expected to improve the survival and integration of transplanted cells, and to support structural, functional, and bioenergetic recovery of the recipient hearts. Specifically, application of a prefabricated cardiac tissue patch to prevent dilation and to improve pumping efficiency of the infarcted heart offers a promising strategy for making stem cell therapy a clinical reality. [Display omitted

Generating multimedia presentations: from plain text to screenplay

In many Natural Language Generation (NLG) applications, the output is limited to plain text – i.e., a string of words with punctuation and paragraph breaks, but no indications for layout, or pictures, or dialogue. In several projects, we have begun to explore NLG applications in which these extra media are brought into play. This paper gives an informal account of what we have learned. For coherence, we focus on the domain of patient information leaflets, and follow an example in which the same content is expressed first in plain text, then in formatted text, then in text with pictures, and finally in a dialogue script that can be performed by two animated agents. We show how the same meaning can be mapped to realisation patterns in different media, and how the expanded options for expressing meaning are related to the perceived style and tone of the presentation. Throughout, we stress that the extra media are not simple added to plain text, but integrated with it: thus the use of formatting, or pictures, or dialogue, may require radical rewording of the text itself

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This work paves the way for a fully integrated quantum technology platform based on the GaAs material system.Comment: 10 pages, 4 figure

New Clues About Light Sterile Neutrinos: Preference for Models with Damping Effects in Global Fits

This article reports global fits of short-baseline neutrino data to oscillation models involving light sterile neutrinos. In the commonly-used 3+1 plane wave model, there is a well-known 4.9$\sigma$ tension between data sets sensitive to appearance and disappearance of neutrinos. We find that models that damp the oscillation prediction for the reactor data sets, especially at low energy, substantially improve the fits and reduce the tension. We consider two such scenarios. The first introduces one sterile neutrino (3+1) and the Quantum Mechanical wavepacket effect that accounts for the source size in reactor experiments. We find that inclusion of the wavepacket effect greatly improves the overall fit compared to the null model by $\Delta \chi^2/\textrm{dof}=60.2/4$ ($7\sigma$ improvement) with best-fit $\Delta m^2=1.4~\textrm{eV}^2$ and wavepacket length of 67 fm; internal tension is reduced to 3.6$\sigma$. If reactor-data only is fit, that the wavepacket preferred length is 91 fm ($>20$ fm at 99\% CL). The second model introduces oscillations involving sterile flavor and allows the decay of the heavier, mostly sterile, mass state $\nu_4$. This model introduces a damping term similar to the wavepacket effect, but across all experiments. Compared to null, this has a $\Delta \chi^2/\textrm{dof}=60.6/4$ ($7\sigma$ improvement) with preferred $\Delta m^2=1.4~\textrm{eV}^2$ and decay $\Gamma = 0.35~\textrm{eV}$; and internal tension of 3.7$\sigma$.Comment: Errors are the prospect plot updated from the collaboration. Tension figures have updated plot styl