31,038 research outputs found
Anyonic statistics with continuous variables
We describe a continuous-variable scheme for simulating the Kitaev lattice
model and for detecting statistics of abelian anyons. The corresponding quantum
optical implementation is solely based upon Gaussian resource states and
Gaussian operations, hence allowing for a highly efficient creation,
manipulation, and detection of anyons. This approach extends our understanding
of the control and application of anyons and it leads to the possibility for
experimental proof-of-principle demonstrations of anyonic statistics using
continuous-variable systems.Comment: 5 pages, 2 figures, appear in Phys. Rev.
Positive mass theorems for asymptotically AdS spacetimes with arbitrary cosmological constant
We formulate and prove the Lorentzian version of the positive mass theorems
with arbitrary negative cosmological constant for asymptotically AdS
spacetimes. This work is the continuation of the second author's recent work on
the positive mass theorem on asymptotically hyperbolic 3-manifolds.Comment: 17 pages, final version, to appear in International Journal of
Mathematic
Modeling Pressure-Ionization of Hydrogen in the Context of Astrophysics
The recent development of techniques for laser-driven shock compression of
hydrogen has opened the door to the experimental determination of its behavior
under conditions characteristic of stellar and planetary interiors. The new
data probe the equation of state (EOS) of dense hydrogen in the complex regime
of pressure ionization. The structure and evolution of dense astrophysical
bodies depend on whether the pressure ionization of hydrogen occurs
continuously or through a ``plasma phase transition'' (PPT) between a molecular
state and a plasma state. For the first time, the new experiments constrain
predictions for the PPT. We show here that the EOS model developed by Saumon
and Chabrier can successfully account for the data, and we propose an
experiment that should provide a definitive test of the predicted PPT of
hydrogen. The usefulness of the chemical picture for computing astrophysical
EOS and in modeling pressure ionization is discussed.Comment: 16 pages + 4 figures, to appear in High Pressure Researc
Electron Delocalization in Gate-Tunable Gapless Silicene
The application of a perpendicular electric field can drive silicene into a
gapless state, characterized by two nearly fully spin-polarized Dirac cones
owing to both relatively large spin-orbital interactions and inversion symmetry
breaking. Here we argue that since inter-valley scattering from non-magnetic
impurities is highly suppressed by time reversal symmetry, the physics should
be effectively single-Dirac-cone like. Through numerical calculations, we
demonstrate that there is no significant backscattering from a single impurity
that is non-magnetic and unit-cell uniform, indicating a stable delocalized
state. This conjecture is then further confirmed from a scaling of conductance
for disordered systems using the same type of impurities.Comment: 6 pages, 3 figures, published versio
Magnetic ordering and structural phase transitions in strained ultrathin SrRuO/SrTiO superlattice
Ruthenium-based perovskite systems are attractive because their Structural,
electronic and magnetic properties can be systematically engineered.
SrRuO/SrTiO superlattice, with its period consisting of one unit cell
each, is very sensitive to strain change. Our first-principles simulations
reveal that in the high tensile strain region, it transits from a ferromagnetic
(FM) metal to an antiferromagnetic (AFM) insulator with clear tilted octahedra,
while in the low strain region, it is a ferromagnetic metal without octahedra
tilting. Detailed analyses of three spin-down Ru-t orbitals just below
the Fermi level reveal that the splitting of these orbitals underlies these
dramatic phase transitions, with the rotational force constant of RuO
octahedron high up to 16 meV/Deg, 4 times larger than that of TiO.
Differently from nearly all the previous studies, these transitions can be
probed optically through the diagonal and off-diagonal dielectric tensor
elements. For one percent change in strain, our experimental spin moment change
is -0.140.06 , quantitatively consistent with our theoretical value
of -0.1 .Comment: 3 figures, 1 supplementary material, accepted by Phys. Rev. Let
Harnessing the Power of Machine Learning in Dementia Informatics Research: Issues, Opportunities and Challenges
Dementia is a chronic and degenerative condition affecting millions globally. The care of patients with dementia presents an ever continuing challenge to healthcare systems in the 21st century. Medical and health sciences have generated unprecedented volumes of data related to health and wellbeing for patients with dementia due to advances in information technology, such as genetics, neuroimaging, cognitive assessment, free texts, routine electronic health records etc. Making the best use of these diverse and strategic resources will lead to high quality care of patients with dementia. As such, machine learning becomes a crucial factor in achieving this objective. The aim of this paper is to provide a state-of-the-art review of machine learning methods applied to health informatics for dementia care. We collate and review the existing scientific methodologies and identify the relevant issues and challenges when faced with big health data. Machine learning has demonstrated promising applications to neuroimaging data analysis for dementia care, while relatively less efforts have been made to make use of integrated heterogeneous data via advanced machine learning approaches. We further indicate the future potentials and research directions of applying advanced machine learning, such as deep learning, to dementia informatics
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