Low Temperature Superfluid Response of High-Tc Superconductors

We have reviewed our theoretical and experimental results of the low temperature superfluid response function of high temperature superconductors (HTSC). In clean high-Tc materials the in-plane superfluid density rho_s^{ab} varies linearly with temperature. The slope of this linear T term is found to scale approximately with 1/Tc which, according to the weak coupling BCS theory for a d-wave superconductor, implies that the gap amplitude scales approximately with Tc. A T^5 behavior of the out-of-plane superfluid density rho_s^c for clean tetragonal HTSC was predicted and observed experimentally in the single layer Hg-compound HgBa_2CuO_{4+delta}. In other tetragonal high-Tc compounds with relatively high anisotropy, such as Hg_2Ba_2Ca_2Cu_3O_{8+delta}, rho_s^c varies as T^2 due to disorder effects. In optimally doped YBa_2Cu_3O_{7-delta}, rho_s^c varies linearly with temperature at low temperatures, but in underdoped YBa_2Cu_3O_{7-delta}, rho_s^c varies as T^2 at low temperatures; these results are consistent with our theoretical calculations.Comment: 26 pages, 8 figure

Development and Verification of a Flight Stack for a High-Altitude Glider in Ada/SPARK 2014

SPARK 2014 is a modern programming language and a new state-of-the-art tool set for development and verification of high-integrity software. In this paper, we explore the capabilities and limitations of its latest version in the context of building a flight stack for a high-altitude unmanned glider. Towards that, we deliberately applied static analysis early and continuously during implementation, to give verification the possibility to steer the software design. In this process we have identified several limitations and pitfalls of software design and verification in SPARK, for which we give workarounds and protective actions to avoid them. Finally, we give design recommendations that have proven effective for verification, and summarize our experiences with this new language

Thermodynamic properties and phase diagrams of spin-1 quantum Ising systems with three-spin interactions

The spin-1 quantum Ising systems with three-spin interactions on two-dimensional triangular lattices are studied by mean-field method. The thermal variations of order parameters and phase diagrams are investigated in detail. The stable, metastable and unstable branches of the order parameters are obtained. According to the stable conditions at critical point, we find that the systems exhibit tricritical points. With crystal field and biquadratic interactions, the system has rich phase diagrams with single reentrant or double reentrant phase transitions for appropriate ranges of the both parameters.Comment: 10 pages, 5 figure

On the Origin and Survival of UHE Cosmic-Ray Nuclei in GRBs and Hypernovae

The chemical composition of the ultra-high-energy (UHE) cosmic rays serves as an important clue for their origin. Recent measurements of the elongation rates by the Pierre Auger Observatory hint at the possible presence of heavy or intermediate mass nuclei in the UHE cosmic rays. Gamma-ray bursts (GRBs) and hypernovae have been suggested as possible sources of the UHE cosmic rays. Here we derive the constraints on the physical conditions under which UHE heavy nuclei, if they are accelerated in these sources, can survive in their intense photon fields. We find that in the GRB external shock and in the hypernova scenarios, UHE nuclei can easily survive photo-disintegration. In the GRB internal shock scenario, UHE nuclei can also survive, provided the dissipation radius and/or the bulk Lorentz factor of the relativistic outflow are relatively large, or if the low-energy self-absorption break in the photon spectrum of the prompt emission occurs above several KeV. In internal shocks and in the other scenarios, intermediate-mass UHE nuclei have a higher probability of survival against photo-disintegration than UHE heavy nuclei such as Fe.Comment: accepted by ApJ, references added, 12 pages, 4 figures, emulateapj styl

Applying Deep Learning to Answer Selection: A Study and An Open Task

We apply a general deep learning framework to address the non-factoid question answering task. Our approach does not rely on any linguistic tools and can be applied to different languages or domains. Various architectures are presented and compared. We create and release a QA corpus and setup a new QA task in the insurance domain. Experimental results demonstrate superior performance compared to the baseline methods and various technologies give further improvements. For this highly challenging task, the top-1 accuracy can reach up to 65.3% on a test set, which indicates a great potential for practical use.Comment: To appear in the proceedings of ASRU 201

Modified dispersion relations and black hole physics

A modified formulation of energy-momentum relation is proposed in the context of doubly special relativity. We investigate its impact on black hole physics. It turns out that such modification will give corrections to both the temperature and the entropy of black holes. In particular this modified dispersion relation also changes the picture of Hawking radiation greatly when the size of black holes approaching the Planck scale. It can prevent black holes from total evaporation, as a result providing a plausible mechanism to treat the remnant of black holes as a candidate for dark matter.Comment: 4 pages, Revtex. Final version to appear in PR