14,726 research outputs found
Antimatter, Lorentz Symmetry, and Gravity
A brief introduction to the Standard-Model Extension (SME) approach to
testing CPT and Lorentz symmetry is provided. Recent proposals for tests with
antimatter are summarized, including gravitational and spectroscopic tests.Comment: Presented at the 12th International Conference on Low Energy
Antiproton Physics, Kanazawa Japan, March 6-11, 2016, Accepted for
publication in JPS Conference Proceeding
Effect of bilayer coupling on tunneling conductance of double-layer high T_c cuprates
Physical effects of bilayer coupling on the tunneling spectroscopy of high
T cuprates are investigated. The bilayer coupling separates the bonding
and antibonding bands and leads to a splitting of the coherence peaks in the
tunneling differential conductance. However, the coherence peak of the bonding
band is strongly suppressed and broadened by the particle-hole asymmetry in the
density of states and finite quasiparticle life-time, and is difficult to
resolve by experiments. This gives a qualitative account why the bilayer
splitting of the coherence peaks was not clearly observed in tunneling
measurements of double-layer high-T oxides.Comment: 4 pages, 3 figures, to be published in PR
Regularization of the Roy Equations with a Smooth Cut-Off
The Roy equations for ππ scattering are combined with unitarity to give a nonlinear system of equations for the determination of the low‐energy amplitudes. A Hölder continuous interpolation between the input high‐energy absorptive parts and the output low‐energy absorptive parts is implemented; and the resultant singular equations are regularized by means of an effective inelastic N/D method. If the scattering lengths, the CDD parameters, and the high‐energy absorptive parts satisfy certain constraints, then there exists a locally unique solution of the system
Extinction of impurity resonances in large-gap regions of inhomogeneous d-wave superconductors
Impurity resonances observed by scanning tunneling spectroscopy in the
superconducting state have been used to deduce properties of the underlying
pure state. Here we study a longstanding puzzle associated with these
measurements, the apparent extinction of these resonances for Ni and Zn
impurities in large-gap regions of the inhomogeneous BSCCO superconductor. We
calculate the effect of order parameter and hopping suppression near the
impurity site, and find that these two effects are sufficient to explain the
missing resonances in the case of Ni. There are several possible scenarios for
the extinction of the Zn resonances, which we discuss in turn; in addition, we
propose measurements which could distinguish among them.Comment: 10 pages, 8 figure
About the maximal rank of 3-tensors over the real and the complex number field
High dimensional array data, tensor data, is becoming important in recent
days. Then maximal rank of tensors is important in theory and applications. In
this paper we consider the maximal rank of 3 tensors. It can be attacked from
various viewpoints, however, we trace the method of Atkinson-Stephens(1979) and
Atkinson-Lloyd(1980). They treated the problem in the complex field, and we
will present various bounds over the real field by proving several lemmas and
propositions, which is real counterparts of their results.Comment: 13 pages, no figure v2: correction and improvemen
Exchanging uncertainty: interoperable geostatistics?
Traditionally, geostatistical algorithms are contained within specialist GIS and spatial statistics software. Such packages are often expensive, with relatively complex user interfaces and steep learning curves, and cannot be easily integrated into more complex process chains. In contrast, Service Oriented Architectures (SOAs) promote interoperability and loose coupling within distributed systems, typically using XML (eXtensible Markup Language) and Web services. Web services provide a mechanism for a user to discover and consume a particular process, often as part of a larger process chain, with minimal knowledge of how it works. Wrapping current geostatistical algorithms with a Web service layer would thus increase their accessibility, but raises several complex issues. This paper discusses a solution to providing interoperable, automatic geostatistical processing through the use of Web services, developed in the INTAMAP project (INTeroperability and Automated MAPping). The project builds upon Open Geospatial Consortium standards for describing observations, typically used within sensor webs, and employs Geography Markup Language (GML) to describe the spatial aspect of the problem domain. Thus the interpolation service is extremely flexible, being able to support a range of observation types, and can cope with issues such as change of support and differing error characteristics of sensors (by utilising descriptions of the observation process provided by SensorML). XML is accepted as the de facto standard for describing Web services, due to its expressive capabilities which allow automatic discovery and consumption by ‘naive’ users. Any XML schema employed must therefore be capable of describing every aspect of a service and its processes. However, no schema currently exists that can define the complex uncertainties and modelling choices that are often present within geostatistical analysis. We show a solution to this problem, developing a family of XML schemata to enable the description of a full range of uncertainty types. These types will range from simple statistics, such as the kriging mean and variances, through to a range of probability distributions and non-parametric models, such as realisations from a conditional simulation. By employing these schemata within a Web Processing Service (WPS) we show a prototype moving towards a truly interoperable geostatistical software architecture
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Functional Imaging of the Outer Retinal Complex using High Fidelity Imaging Retinal Densitometry
We describe a new technique, high fidelity Imaging Retinal Densitometry (IRD), which probes the functional integrity of the outer retinal complex. We demonstrate the ability of the technique to map visual pigment optical density and synthesis rates in eyes with and without macular disease. A multispectral retinal imaging device obtained precise measurements of retinal reflectance over space and time. Data obtained from healthy controls and 5 patients with intermediate AMD, before and after photopigment bleaching, were used to quantify visual pigment metrics. Heat maps were plotted to summarise the topography of rod and cone pigment kinetics and descriptive statistics conducted to highlight differences between those with and without AMD. Rod and cone visual pigment synthesis rates in those with AMD (v = 0.043 SD 0.019 min-1 and v = 0.119 SD 0.046 min-1, respectively) were approximately half those observed in healthy controls (v = 0.079 SD 0.024 min-1 for rods and v = 0.206 SD 0.069 min-1 for cones). By mapping visual pigment kinetics across the central retina, high fidelity IRD provides a unique insight into outer retinal complex function. This new technique will improve the phenotypic characterisation, diagnosis and treatment monitoring of various ocular pathologies, including AMD
An "Accidental" Symmetry Operator for the Dirac Equation in the Coulomb Potential
On the basis of the generalization of the theorem about K-odd operators (K is
the Dirac's operator), certain linear combination is constructed, which appears
to commute with the Dirac Hamiltonian for Coulomb field. This operator
coincides with the Johnson and Lippmann operator and is intimately connected to
the familiar Laplace-Runge-Lenz vector. Our approach guarantees not only
derivation of Johnson-Lippmann operator, but simultaneously commutativity with
the Dirac Hamiltonian follows.Comment: 6 page
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