56 research outputs found
Pairwise Quantum Correlations for Superpositions of Dicke States
Pairwise correlation is really an important property for multi-qubit states.
For the two-qubit X states extracted from Dicke states and their superposition
states, we obtain a compact expression of the quantum discord by numerical
check. We then apply the expression to discuss the quantum correlation of the
reduced two-qubit states of Dicke states and their superpositions, and the
results are compared with those obtained by entanglement of formation, which is
a quantum entanglement measure.Comment: 17pages, 8 figures,slightly improved and slightly extended
version,and added some reference
The association between periodontal disease and the risk of myocardial infarction: a pooled analysis of observational studies
Quality scores of caseâcontrol and cohort studies using Newcastle-Ottawa Scale. (PDF 37 kb
The one-way unlocalizable quantum discord
In this paper, we present the concept of the one-way unlocalizable quantum
discord and investigate its properties. We provide a polygamy inequality for it
in tripartite pure quantum system of arbitrary dimension. Several tradeoff
relations between the one-way unlocalizable quantum discord and other
correlations are given. If the von Neumann measurement is on a part of the
system, we give two expressions of the one-way unlocalizable quantum discord in
terms of partial distillable entanglement and quantum disturbance. Finally, we
also provide a lower bound for bipartite shareability of quantum correlation
beyond entanglement in a tripartite system.Comment: 6 pages, 3 figures. Minor corrections, references adde
Necessary and sufficient condition for saturating the upper bound of quantum discord
We revisit the upper bound of quantum discord given by the von Neumann
entropy of the measured subsystem. Using the Koashi-Winter relation, we obtain
a trade-off between the amount of classical correlation and quantum discord in
the tripartite pure states. The difference between the quantum discord and its
upper bound is interpreted as a measure on the classical correlative capacity.
Further, we give the explicit characterization of the quantum states saturating
the upper bound of quantum discord, through the equality condition for the
Araki-Lieb inequality. We also demonstrate that the saturating of the upper
bound of quantum discord precludes any further correlation between the measured
subsystem and the environment.Comment: 5 pages, 1figures, version accepted Phys.Rev.A, 85, 032109 (2012
The retropharyngeal reduction plate for atlantoaxial dislocation: a finite element analysis
Objective: To investigate the biomechanical properties of the retropharyngeal reduction plate by comparing the traditional posterior pedicle screw-rod fixation by finite element analysis.Methods: Two three-dimensional finite element digital models of the retropharyngeal reduction plate and posterior pedicle screw-rod fixation were constructed and validated based on the DICOM (Digital Imaging and Communications in Medicine) data from C1 to C4. The biomechanical finite element analysis values of two internal fixations were measured and calculated under different conditions, including flexion, extension, bending, and rotation.Results: In addition to the backward extension, there was no significant difference in the maximum von Mises stress between the retropharyngeal reduction plate and posterior pedicle screw fixation under other movement conditions. The retropharyngeal reduction plate has a more uniform distribution under different conditions, such as flexion, extension, bending, and rotation. The stress tolerance of the two internal fixations was basically consistent in flexion, extension, left bending, and right bending.Conclusion: The retropharyngeal reduction plate has a relatively good biomechanical stability without obvious stress concentration under different movement conditions. It shows potential as a fixation option for the treatment of atlantoaxial dislocation
Measurement-induced nonlocality based on the relative entropy
We quantify the measurement-induced nonlocality [Luo and Fu, Phys. Rev. Lett.
106, 120401 (2011)] from the perspective of the relative entropy. This
quantification leads to an operational interpretation for the
measurementinduced nonlocality, namely, it is the maximal entropy increase
after the locally invariant measurements. The relative entropy of nonlocality
is upper bounded by the entropy of the measured subsystem. We establish a
relationship between the relative entropy of nonlocality and the geometric
nonlocality based on the Hilbert- Schmidt norm, and show that it is equal to
the maximal distillable entanglement. Several trade-off relations are obtained
for tripartite pure states. We also give explicit expressions for the relative
entropy of nonlocality for Bell-diagonal states.Comment: 5 pages, 1 figures, version accepted Phys. Rev. A, PHYSICAL REVIEW A
85, 042325 (2012
Biomechanical evaluation of different posterior fixation techniques for treating thoracolumbar burst fractures of osteoporosis old patients: a finite element analysis
Objective: To investigate the biomechanical characteristics of different posterior fixation techniques in treatment of osteoporotic thoracolumbar burst fractures by finite element analysis.Methods: The Dicom format images of T10-L5 segments were obtained from CT scanning of a volunteer, and transferred to the Geomagic Studio software, which was used to build digital models. L1 osteoporotic burst fracture and different posterior fixation techniques were simulated by SolidWorks software. The data of ROM, the maximum displacement of fixed segment, ROM of fractured L1 vertebrae, the stress on the screws and rods as well as on fractured L1 vertebrae under different movement conditions were collected and analysed by finite element analysis.Results: Among the four groups, the largest ROM of fixed segment, the maximum displacement of fixed segment and ROM of fractured vertebrae occurred in CBT, and the corresponding data was 1.3°, 2.57 mm and 1.37°, respectively. While the smallest ROM of fixed segment, the maximum displacement of fixed segment and ROM of fractured vertebrae was found in LSPS, and the corresponding data was 0.92°, 2.46 mm and 0.89°, respectively. The largest stress of screws was 390.97 Mpa, appeared in CBT, and the largest stress of rods was 84.68 MPa, appeared in LSPS. The stress concentrated at the junction area between the root screws and rods. The maximum stress on fractured vertebrae was 93.25 MPa, appeared in CBT and the minimum stress was 56.68 MPa, appeared in CAPS. And the stress of fractured vertebrae concentrated in the middle and posterior column of the fixed segment, especially in the posterior edge of the superior endplate.Conclusion: In this study, long-segment posterior fixation (LSPF) provided with the greatest stability of fixed segment after fixation, while cortical bone screw fixation (CBT) provided with the smallest stability. Cement-augmented pedicle screw-rod fixation (CAPS) and combined using cortical bone screw and pedicle screw fixation (CBT-PS) provided with the moderate stability. CBT-PS exhibited superiority in resistance of rotational torsion for using multiple connecting rods. CAPS and CBT-PS maybe biomechanically superior options for the surgical treatment of burst TL fractures in osteoporotic patients
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