Search results for "Cross-correlation"

Automatic Extraction of Blood Vessels, Bifurcations and End Points in the Retinal Vascular Tree

2008

In this paper we present an effective algorithm for automated extraction of the vascular tree in retinal images, including bifurcations, crossovers and end-points detection. Correct identification of these features in the ocular fundus helps the diagnosis of important systematic diseases, such as diabetes and hypertension. The pre-processing consists in artefacts removal based on anisotropic diffusion filter. Then a matched filter is applied to enhance blood vessels. The filter uses a full adaptive kernel because each vessel has a proper orientation and thickness. The kernel of the filter needs to be rotated for all possible directions. As a consequence, a suitable kernel has been designed …

When financial economics influences physics: The role of Econophysics

2019

This paper aims at analyzing the unexpected influence of Financial economics on Physics. The rise of Econophysics, a fundamentally new approach in finance, suggests that the influence between the two disciplines becomes less unilateral than in the past. Methodological debates emerging in Econophysics led physicists to acknowledge that dealing with financial complex systems contributed to a wider modelling of their field. The approach of econophysicists suggests that physicists might try to conceptualize physical phenomena by integrating elements they faced with in Financial economics, and more generally in Economics. Surprisingly, many of econophysicists’ argumentations have some methodolog…

A New Dissimilarity Measure for Clustering Seismic Signals

2011

Hypocenter and focal mechanism of an earthquake can be determined by the analysis of signals, named waveforms, related to the wave field produced and recorded by a seismic network. Assuming that waveform similarity implies the similarity of focal parameters, the analysis of those signals characterized by very similar shapes can be used to give important details about the physical phenomena which have generated an earthquake. Recent works have shown the effectiveness of cross-correlation and/or cross-spectral dissimilarities to identify clusters of seismic events. In this work we propose a new dissimilarity measure between seismic signals whose reliability has been tested on real seismic dat…

CROSS-POWER SPECTRAL DENSITY AND CROSS-CORRELATION REPRESENTATION BY USING FRACTIONAL SPECTRAL MOMENTS

2012

Scanning near-field optical microscopy using semiconductor nanocrystals as a local fluorescence and fluorescence resonance energy transfer source

2003

Local fluorescence probes based on CdSe semiconductor nanocrystals were prepared and tested by recording scanning near-field optical microscopy (SNOM) images of calibration samples and fluorescence resonance energy transfer SNOM (FRET SNOM) images of acceptor dye molecules inhomogeneously deposited onto a glass substrate. Thousands of nanocrystals contribute to the signal when this probe is used as a local fluorescence source while only tens of those (the most apical) are involved in imaging for the FRET SNOM operation mode. The dip-coating method used to make the probe enables diminishing the number of active fluorescent nanocrystals easily. Prospects to realize FRET SNOM based on a single…

Synergistic Information Transfer in the Global System of Financial Markets.

2020

Uncovering dynamic information flow between stock market indices has been the topic of several studies which exploited the notion of transfer entropy or Granger causality, its linear version. The output of the transfer entropy approach is a directed weighted graph measuring the information about the future state of each target provided by the knowledge of the state of each driving stock market index. In order to go beyond the pairwise description of the information flow, thus looking at higher order informational circuits, here we apply the partial information decomposition to triplets consisting of a pair of driving markets (belonging to America or Europe) and a target market in Asia. Our …

Time resolved confocal luminescence investigations on reverse proton exchange Nd : LiNbO3 channel waveguides

2009

In this work we report on the time and spatial resolved fluorescence of Neodymium ions in LiNbO(3) channel waveguides fabricated by Reverse Proton Exchange. The analysis of the fluorescence decay curves obtained with a sub-micrometric resolution has evidenced the presence of a relevant fluorescence quenching inside the channel waveguide. From the comparison between diffusion simulations and the spatial dependence of the (4)F(3/2) fluorescence decay rate we have concluded that the observed fluorescence quenching can be unequivocally related to the presence of H+ ions in the LiNbO(3) lattice. Nevertheless, it turns out that Reverse Proton Exchange guarantees a fluorescence quenching level sig…

Direct temporal reconstruction of picosecond pulse by cross-correlation in semiconductor device

2012

Cross-correlation measurements using the two-photon absorption process in a semiconductor is experimentally demonstrated for two pulses of different wavelengths (shifted by ~200 nm) and durations (20 times ratio). These measurements were found to be highly repeatable and fully suitable for the determination of the temporal intensity profile of picosecond (ps) pulses.

Easy-use and low-cost fiber-based two-color dynamic light-scattering apparatus

2011

We present a small and compact two-color cross-correlation light-scattering setup designed to study the structure and dynamics of colloidal suspensions in the regime of considerable turbidity. Using a homemade concentric four-arm goniometer, combined with fiber-optical illumination and detection devices, allows an easy and long time stable alignment-even under a temperature variation of ∼5 °C. Tests with a nearly multiple scattering free suspension of small Rayleigh scatterers show intercepts in cross correlation near 0.4 over a wide range of scattering angles from 20° to 150°. Measuring slightly turbid samples in cross-correlation mode multiple scattering is sufficiently suppressed allowin…

Thermal restraint of a bacterial exopolysaccharide of shallow vent origin

2018

This is the post-print version of the following article: "Thermal restraint of a bacterial exopolysaccharide of shallow vent origin", which has been published in final form at https://www.sciencedirect.com/science/article/pii/S0141813018308250?via%3Dihub; International audience; To dynamically characterize the thermal properties of the fructose-rich exopolysaccharide (EPS1-T14), produced by themarine thermophilic Bacillus licheniformis T14, the Attenuated Total Reflectance Fourier Transform Infra-Redspectroscopy was coupled to variable temperature ranging from ambient to 80 °C.The spectra were analyzed by the following innovative mathematical tools: i) non-ideal spectral deviation, ii) OHst…