2,663 research outputs found
Gapped quantum liquids and topological order, stochastic local transformations and emergence of unitarity
In this work we present some new understanding of topological order,
including three main aspects: (1) It was believed that classifying topological
orders corresponds to classifying gapped quantum states. We show that such a
statement is not precise. We introduce the concept of \emph{gapped quantum
liquid} as a special kind of gapped quantum states that can "dissolve" any
product states on additional sites. Topologically ordered states actually
correspond to gapped quantum liquids with stable ground-state degeneracy.
Symmetry-breaking states for on-site symmetry are also gapped quantum liquids,
but with unstable ground-state degeneracy. (2) We point out that the
universality classes of generalized local unitary (gLU) transformations
(without any symmetry) contain both topologically ordered states and
symmetry-breaking states. This allows us to use a gLU invariant -- topological
entanglement entropy -- to probe the symmetry-breaking properties hidden in the
exact ground state of a finite system, which does not break any symmetry. This
method can probe symmetry- breaking orders even without knowing the symmetry
and the associated order parameters. (3) The universality classes of
topological orders and symmetry-breaking orders can be distinguished by
\emph{stochastic local (SL) transformations} (i.e.\ \emph{local invertible
transformations}): small SL transformations can convert the symmetry-breaking
classes to the trivial class of product states with finite probability of
success, while the topological-order classes are stable against any small SL
transformations, demonstrating a phenomenon of emergence of unitarity. This
allows us to give a new definition of long-range entanglement based on SL
transformations, under which only topologically ordered states are long-range
entangled.Comment: Revised version. Figures and references adde
A readily accessible multifunctional probe: simultaneous recognition of the cation ZN²⁺ and the anion F⁻ via distinguishable wavelengths
The probe 1 was readily prepared via condensation of 8-formyl-7-hydroxy-coumarin and carbonic dihydrazide in a one-step procedure. Probe 1 exhibited high sensitivity and selectivity towards Zn²⁺ and F⁻ through a “turn-on” fluorescence response and/or ratiometric colorimetric response with low detection limits of the order of 10-8 M. The complex behaviour was fully investigated by spectral titration, isothermal titration calorimetry, 1H NMR spectroscopic titration and mass spectrometry. Interestingly, probe 1 not only recognizes the cation Zn²⁺ and the anion F⁻, but can also distinguish between these two ions via the max wavelength in their UV-vis spectra (360 nm for 1-Zn²⁺ versus 400 nm for 1-F⁻ complex) or their fluorescent spectra (λₑₓ / λₑm = 360 nm/ 454 nm for 1-Zn²⁺ versus λₑₓ / λₑm = 400 nm/ 475 nm for 1-F⁻ complex) due to their differing red-shifts. Additionally, probe 1 has been further explored in the detection of Zn²⁺ in living cells
Identifying Patch Correctness in Test-Based Program Repair
Test-based automatic program repair has attracted a lot of attention in
recent years. However, the test suites in practice are often too weak to
guarantee correctness and existing approaches often generate a large number of
incorrect patches.
To reduce the number of incorrect patches generated, we propose a novel
approach that heuristically determines the correctness of the generated
patches. The core idea is to exploit the behavior similarity of test case
executions. The passing tests on original and patched programs are likely to
behave similarly while the failing tests on original and patched programs are
likely to behave differently. Also, if two tests exhibit similar runtime
behavior, the two tests are likely to have the same test results. Based on
these observations, we generate new test inputs to enhance the test suites and
use their behavior similarity to determine patch correctness.
Our approach is evaluated on a dataset consisting of 139 patches generated
from existing program repair systems including jGenProg, Nopol, jKali, ACS and
HDRepair. Our approach successfully prevented 56.3\% of the incorrect patches
to be generated, without blocking any correct patches.Comment: ICSE 201
Investigating the Nature of EFL Pair Interactions in a Computer-Mediated Communication Task
In this article. we examined the patterns of pair interactions that emerged in a computermediated text-reconstruction task where 16 Chinese tertiary EFL learners worked in eight self-selected pairs in the chat rooms. This study drew on Storch's (2002) work on the nature of ESL pair work. Quantitative and qualitative data presented in this study suggested that six pairs fell under one of Storch's four patterns of interaction. The interactions of two pairs were more dynamic and did not match any of the four patterns. We did not find the significant relationship between thc pair patterns and the performance of their individualized posttests developed from language-related episodes during interaction. However, we did find that learning is more likely to occur when learners collaborate and jointly work out a successful solution in case of an emerging problem than when they have disagreements and cannot finally resolve them.</p
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