15,389 research outputs found
Quantum teleportation via two qubit Heisenberg XY chain - Effects of anisotropy and magnetic field
In this paper, we study the influence of anisotropy on the usefulness, of the
entanglement in a two-qubit Heisenberg XY chain at thermal equilibrium in the
presence of an external magnetic field, as resource for quantum teleportation
via the standard teleportation protocol. We show that the nonzero thermal
entanglement produced by adjusting the external magnetic field strength beyond
some critical strength is a useful resource. We also considered entanglement
teleportation via two two-qubit Heisenberg XY chains.Comment: 12 pages, 1 figur
Quantum Mechanical Search and Harmonic Perturbation
Perturbation theory in quantum mechanics studies how quantum systems interact
with their environmental perturbations. Harmonic perturbation is a rare special
case of time-dependent perturbations in which exact analysis exists. Some
important technology advances, such as masers, lasers, nuclear magnetic
resonance, etc., originated from it. Here we add quantum computation to this
list with a theoretical demonstration. Based on harmonic perturbation, a
quantum mechanical algorithm is devised to search the ground state of a given
Hamiltonian. The intrinsic complexity of the algorithm is continuous and
parametric in both time T and energy E. More precisely, the probability of
locating a search target of a Hamiltonian in N-dimensional vector space is
shown to be 1/(1+ c N E^{-2} T^{-2}) for some constant c. This result is
optimal. As harmonic perturbation provides a different computation mechanism,
the algorithm may suggest new directions in realizing quantum computers.Comment: 6 pages, 4 figures, revtex
Optical transmittance of multilayer graphene
We study the optical transmittance of multilayer graphene films up to 65
layers thick. By combing large-scale tight-binding simulation and optical
measurement on CVD multilayer graphene, the optical transmission through
graphene films in the visible region is found to be solely determined by the
number of graphene layers. We argue that the optical transmittance measurement
is more reliable in the determination of the number of layers than the commonly
used Raman Spectroscopy. Moreover, optical transmittance measurement can be
applied also to other 2D materials with weak van der Waals interlayer
interaction.Comment: Europhysics Letters (2014
Establishing isothermal contact at a known temperature under thermal equilibrium in elevated temperature instrumented indentation testing
Trait Sensitivity, Anxiety and Personality are predictive of Central Sensitisation Symptoms in Patients with Chronic Low Back Pain.
BACKGROUND:Sensitivity-related trait characteristics involving physical and emotional sensitivities and high trait anxiety personality types have been observed in individuals with non-specific chronic low back pain (NSCLBP). High trait sensitivity to sensory stimulation combined with interpretation biases based on personality type may contribute to the development of central sensitisation (CS) symptoms. To date there is limited research that has considered both sensitivity levels and personality type in NSCLBP with CS. The purpose of this study was to investigate 1) relationships between trait sensory profiles, trait anxiety and CS symptoms, and 2) the predictive capacity of sensory profiles, trait anxiety and personality types on CS symptoms, in people with NSCLBP. METHODS:This was a cross-sectional observational study using four self-report measures on adults (N = 165, mean age = 45 +-12 SD) from physiotherapy clinics in England, Ireland and New Zealand. Inclusion: NSCLBP > 6 months, aged 18-64, predominant CS pain presentation, no other pathology. Parametric and non-parametric correlation statistics and regression analyses were used. RESULTS:Positive correlations were found between central sensitisation inventory (CSI) scores and sensory hyper-sensitivity profiles and trait anxiety. CSI score increases could be predicted by: Sensory Sensitive, Low Registration profiles, trait anxiety scores and extreme defensive high anxious personality type. CONCLUSIONS:Trait sensory hyper- and/or hypo-sensitivity and high trait-anxiety related personality type characteristics predicts the extent of CS symptoms in people with NSCLBP. Further investigation is required to establish causality between these characteristics and CS symptoms. This article is protected by copyright. All rights reserved
"Optical conductance fluctuations: diagrammatic analysis in Landauer approach and non-universal effects"
The optical conductance of a multiple scattering medium is the total
transmitted light of a diffuse incoming beam. This quantity, very analogous to
the electronic conductance, exhibits universal conductance fluctuations. We
perform a detailed diagrammatic analysis of these fluctuations. With a
Kadanoff-Baym technique all the leading diagrams are systematically generated.
A cancellation of the short distance divergencies occurs, that yields a well
behaved theory. The analytical form of the fluctuations is calculated and
applied to optical systems. Absorption and internal reflections reduce the
fluctuations significantly.Comment: 25 pages Revtex 3.0, 18 seperate postscript figure
The impact of aquaculture soundscapes on whiteleg shrimp Litopenaeus vannamei and Atlantic salmon Salmo salar
Dynamic maps: a visual-analytic methodology for exploring spatio-temporal disease patterns
<p>Abstract</p> <p>Background</p> <p>Epidemiologic studies are often confounded by the human and environmental interactions that are complex and dynamic spatio-temporal processes. Hence, it is difficult to discover nuances in the data and generate pertinent hypotheses. Dynamic mapping, a method to simultaneously visualize temporal and spatial information, was introduced to elucidate such complexities. A conceptual framework for dynamic mapping regarding principles and implementation methods was proposed.</p> <p>Methods</p> <p>The spatio-temporal dynamics of <it>Salmonella </it>infections for 2002 in the U.S. elderly were depicted via dynamic mapping. Hospitalization records were obtained from the Centers of Medicare and Medicaid Services. To visualize the spatial relationship, hospitalization rates were computed and superimposed onto maps of environmental exposure factors including livestock densities and ambient temperatures. To visualize the temporal relationship, the resultant maps were composed into a movie.</p> <p>Results</p> <p>The dynamic maps revealed that the <it>Salmonella </it>infections peaked at specific spatio-temporal loci: more clusters were observed in the summer months and higher density of such clusters in the South. The peaks were reached when the average temperatures were greater than 83.4°F (28.6°C). Although the relationship of salmonellosis rates and occurrence of temperature anomalies was non-uniform, a strong synchronization was found between high broiler chicken sales and dense clusters of cases in the summer.</p> <p>Conclusions</p> <p>Dynamic mapping is a practical visual-analytic technique for public health practitioners and has an outstanding potential in providing insights into spatio-temporal processes such as revealing outbreak origins, percolation and travelling waves of the diseases, peak timing of seasonal outbreaks, and persistence of disease clusters.</p
Recognizing and Drawing IC-planar Graphs
IC-planar graphs are those graphs that admit a drawing where no two crossed
edges share an end-vertex and each edge is crossed at most once. They are a
proper subfamily of the 1-planar graphs. Given an embedded IC-planar graph
with vertices, we present an -time algorithm that computes a
straight-line drawing of in quadratic area, and an -time algorithm
that computes a straight-line drawing of with right-angle crossings in
exponential area. Both these area requirements are worst-case optimal. We also
show that it is NP-complete to test IC-planarity both in the general case and
in the case in which a rotation system is fixed for the input graph.
Furthermore, we describe a polynomial-time algorithm to test whether a set of
matching edges can be added to a triangulated planar graph such that the
resulting graph is IC-planar
Statistical Properties of Charmonium Spectrum and a New Mechanism of J/\psi Suppression
The statistical properties of Charmonium energy spectrum determined by the
Bethe-Salpeter equation are investigated. It is found that the regular motion
of the system can be expected at a small value of color screening
mass but the chaotic motion at a large one. It is shown that the level mixing
due to color screening serves as a new mechanism resulting in the J/
suppression. Moreover, this kind of suppression can occur before the color
screening mass reaches its critical value for J/ dissociation. It implies
that a strong J/ suppression is possible in the absence of dissociation
of J/.Comment: 13 latex pages, 2 figures. Phys. Rev. C in pres
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