Search results for "Coherence"
showing 10 items of 905 documents
An improved method for estimating the frequency correlation function
2012
For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer fun…
Parametric and nonparametric methods to generate time-varying surrogate data.
2009
We present both nonparametric and parametric approaches to generating time-varying surrogate data. Nonparametric and parametric approaches are based on the use of the short-time Fourier transform and a time-varying autoregressive model, respectively. Time-varying surrogate data (TVSD) can be used to determine the statistical significance of the linear and nonlinear coherence function estimates. Two advantages of the TVSD are that it keeps one from having to make an arbitrary decision about the significance of the coherence value, and it properly takes into account statistical significance levels, which may change with time. Our simulation examples and experimental results on blood pressure …
Sense of coherence and psychological well-being among coronary heart disease patients: a moderated mediation model of affect and meaning in life
2020
AbstractThere are credible data that the indirect relationship of sense of coherence with well-being can involve potential mediation and moderation mechanisms related to emotional and meaning-oriented factors. The self-concordance model provides a theoretical framework through which these associations can be examined. The current research explored whether the relationship between sense of coherence and well-being in people with coronary heart disease can be mediated by affect and simultaneously moderated by meaning in life. A total of 176 patients with coronary heart disease completed four questionnaires. Positive and negative affect turned out to mediate, though differently, the relationsh…
Immune-Mediated Desquamative Gingivitis and Optical Coherence Tomography Diagnostic Patterns: Clinical Implication from a Systematic Review
2021
Desquamative Gingivitis (DG) comprises heterogeneous clinical manifestations of numerous immune-mediated muco-cutaneous diseases. Optical Coherence Tomography (OCT) has been proposed as a valuable diagnostic support even if, to date, there are no standardized OCT-diagnostic patterns applicable to DGs. A systematic review was performed to detect existing data on in vivo OCT diagnostic patterns of the most common immune-mediated DGs (i.e., pemphigus vulgaris, mucous membrane pemphigoid and oral lichen planus). It has been found that OCT exhibits specific patterns that address the diagnosis of DG by pemphigus vulgaris (i.e., intraepithelial unilocular blister, reduced epithelial thickness, pre…
Divided attention in music
2000
Two models have been advanced to account for the apparent ease with which attention can be divided in music: a “divided attention” model postulates that listeners effectively manage to follow two or more melodic lines played simultaneously. According to a “figure-ground model,” the harmonic coherence of Western polyphonies allows a listener to focus on one melody while staying aware of the other melody, which acts as a background. This figure-ground processing compensates for the inability to divide attention. The present study was designed to further investigate these two models. Participants were required to detect melodic errors in two familiar nursery tunes played simultaneously an octa…
Analyzing the Energy Efficiency of the Memory Subsystem in Multicore Processors
2014
In this paper we analyze the energy overhead incurred when operating with data stored in different levels of the memory subsystem (cache levels and DDR chips) of current multicore architectures. Our approach builds upon servet, a portable framework for the memory characterization of multicore processors, extending this suite with a power-related test that, when applied to a platform equipped with a power measurement mechanism, provides information on the efficiency of memory energy usage. As additional contributions, i) we provide a complete experimental study of the impact that the CPU performance states (also known as P-states) exert on the memory energy efficiency of a collection of rece…
Extending Quantum Links: Modules for Fiber‐ and Memory‐Based Quantum Repeaters
2020
We analyze elementary building blocks for quantum repeaters based on fiber channels and memory stations. Implementations are considered for three different physical platforms, for which suitable components are available: quantum dots, trapped atoms and ions, and color centers in diamond. We evaluate and compare the performances of basic quantum repeater links for these platforms both for present-day, state-of-the-art experimental parameters as well as for parameters that could in principle be reached in the future. The ultimate goal is to experimentally explore regimes at intermediate distances, up to a few 100 km, in which the repeater-assisted secret key transmission rates exceed the maxi…
A MEMS array-type Mirau interferometer for swept-source OCT imaging with applications in dermatology
2017
In the frame the European project VIAMOS (www.viamos.eu) we developed a microsystem based on Mirau interferometry and applied for optical coherence tomography (OCT) imaging of living tissues. The objective is to benefit from advanced MOEMS technologies, enabling a new generation of miniature and low-cost instruments using the concept of the swept-source OCT (SS-OCT) microsystem based on spectrally tuned Mirau interferometry, into which a doublet of microlens matrices (4×4) and a wafer of movable reference mirrors are included, building the active Mirau interferometer.
Evaluation of a Completely Robotized Neurosurgical Operating Microscope
2012
BACKGROUND Operating microscopes are essential for most neurosurgical procedures. Modern robot-assisted controls offer new possibilities, combining the advantages of conventional and automated systems. OBJECTIVE We evaluated the prototype of a completely robotized operating microscope with an integrated optical coherence tomography module. METHODS A standard operating microscope was fitted with motors and control instruments, with the manual control mode and balance preserved. In the robot mode, the microscope was steered by a remote control that could be fixed to a surgical instrument. External encoders and accelerometers tracked microscope movements. The microscope was additionally fitted…
Time dispersion characterization for UWB mobile radio channels between 3.1 and 10.6 GHz
2007
In this paper, a characterization of the UWB mobile radio channel time dispersion is presented. The results provided were obtained from a measurement campaign carried out in a typical indoor office scenario in the band from 3.1 to 10.6 GHz. Time dispersion metrics as delay spread, coherence bandwidth, delay interval and delay window, in both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions are provided.