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41.
Artifact removal in magnetoencephalogram background activity with independent component analysis 总被引:2,自引:0,他引:2
Escudero J Hornero R Abásolo D Fernández A López-Coronado M 《IEEE transactions on bio-medical engineering》2007,54(11):1965-1973
The aim of this study was to assess whether independent component analysis (ICA) could be valuable to remove power line noise, cardiac, and ocular artifacts from magnetoencephalogram (MEG) background activity. The MEGs were recorded from 11 subjects with a 148-channel whole-head magnetometer. We used a statistical criterion to estimate the number of independent components. Then, a robust ICA algorithm decomposed the MEG epochs and several methods were applied to detect those artifacts. The whole process had been previously tested on synthetic data. We found that the line noise components could be easily detected by their frequency spectrum. In addition, the ocular artifacts could be identified by their frequency characteristics and scalp topography. Moreover, the cardiac artifact was better recognized by its skewness value than by its kurtosis one. Finally, the MEG signals were compared before and after artifact rejection to evaluate our method. 相似文献
42.
A CMOS current-mode approach for implementing the defuzzification function in analogue fuzzy controllers is proposed. The circuit computes the centre of area of the output fuzzy conclusion using switched current adders and a current divider. Simulation results of the defuzzifier show how the circuit can produce a good approximation of the centre of area even if a small number of levels are used to quantise the output variable.<> 相似文献
43.
Pereda J.A. Vielva L.A. Solano M.A. Vegas A. Prieto A. 《Microwave Theory and Techniques》1995,43(2):350-357
The finite-difference time-domain (FDTD) method is extended to include magnetized ferrites. The treatment of the ferrite material is based on the equation of motion of the magnetization vector. Magnetic losses are also included in the equation of motion by means of Gilbert's approximation of the phenomenological Landau-Lifschitz damping term. The discretization scheme is based on central finite-differences and linear interpolation. This scheme allows the fully explicit nature of the FDTD method to be maintained. This extension of the FDTD method to magnetized ferrites is applied to the full-wave analysis of ferrite-loaded waveguides. The dispersion curves are calculated by using a recently proposed 2D-FDTD formulation for dispersion analysis which has been adapted to the present problem. The results for both the phase and attenuation constants of various transversely and longitudinally magnetized ferrite-loaded waveguides are compared with the exact values and with those obtained by means of Schelkunoff's method 相似文献
44.
Marianna Rossetti Lorenzo Stella Judit Morlà-Folch Sara Bobone Ariadna Boloix Lorena Baranda Danila Moscone Mònica Roldán Jaume Veciana Miguel F. Segura Mariana Köber Nora Ventosa Alessandro Porchetta 《Advanced functional materials》2021,31(46):2103511
The development of artificial vesicles into responsive architectures capable of sensing the biological environment and simultaneously signaling the presence of a specific target molecule is a key challenge in a range of biomedical applications from drug delivery to diagnostic tools. Herein, the rational design of biomimetic DNA-grafted quatsome (QS) nanovesicles capable of translating the binding of a target molecule to amphiphilic DNA probes into an optical output is presented. QSs are synthetic lipid-based nanovesicles able to confine multiple organic dyes at the nanoscale, resulting in ultra-bright soft materials with attractiveness for sensing applications. Dye-loaded QS nanovesicles of different composition and surface charge are grafted with fluorescent amphiphilic nucleic acid-based probes to produce programmable FRET-active nanovesicles that operate as highly sensitive signal transducers. The photophysical properties of the DNA-grafted nanovesicles are characterized and the highly selective, ratiometric detection of clinically relevant microRNAs with sensitivity in the low nanomolar range are demonstrated. The potential applications of responsive QS nanovesicles for biosensing applications but also as functional nanodevices for targeted biomedical applications is envisaged. 相似文献
45.
Bazil Taha?AhmedEmail author Miguel Calvo?Ramón Leandro?De?Haro Ariet 《Wireless Personal Communications》2004,31(1-2):19-31
The uplink capacity and the interference statistics (mean and variance) of the sectors of the cigar-shaped W-CDMA microcell are studied. A model with eighteen sectors is used to analyze the uplink. The microcells are assumed to exist in a long tunnel with at least nine base stations. The hybrid model of propagation is used in the calculations. The capacity and the interference statistics of the sectors are studied in terms of the most important parameters: sector radius, specific attenuation factor, antenna sidelobe levels, bend losses and the power control standard deviation error. 相似文献
46.
This article presents the first results of our study and experimentation with the new IPv6 IX-based address assignment model and its deployment in IXs where peering is organized around route servers. An IX model that identifies where the new IX customers can be located and how services like provider choice or multihoming can be offered is proposed. The article also describes the emulation environment that has been developed to easily create and experiment with complex IX scenarios without involving setup of costly configurations made of several pieces of equipment. This work has been carried out in the context of the European Union funded project Euro6IX. 相似文献
47.
Suman Mukherjee John Federici Paulo Lopes Miguel Cabral 《Journal of Infrared, Millimeter and Terahertz Waves》2013,34(9):539-555
For the past few decades there has been tremendous innovation and development of Terahertz (THz) science and imaging. In particular, the technique of 3-D computed tomography has been adapted from the X-Ray to the THz range. However, the finite refractive index of materials in the THz range can severally refract probing THz beams during the acquisition of tomography data. Due to Fresnel reflection power losses at the boundaries as well as steering of the THz beam through the sample, refractive effects lead to anomalously high local attenuation coefficients near the material boundaries of a reconstructed image. These boundary phenomena can dominate the reconstructed THz-CT images making it difficult to distinguish structural defect(s) inside the material. In this paper an algorithm has been developed to remove the effects of refraction in THz-CT reconstructed images. The algorithm is successfully implemented on cylindrical shaped objects. 相似文献
48.
Gomila D. Colet P. San Miguel M. Scroggie A.J. Oppo G.-L. 《Quantum Electronics, IEEE Journal of》2003,39(2):238-244
Two kinds of cavity solitons, stable circular domain walls (droplets) and dark-ring cavity solitons, are presented in models of vectorial Kerr resonators and degenerate optical parametric oscillators. These structures are universal in systems with two equivalent homogeneous states and are found for parameter values close to those of a modulational instability of a flat front. Stable droplets owe their existence to curvature effects and, therefore, they are not present in one-dimensional systems. We show that stable droplets nucleate out of dark-ring cavity solitons and that in some systems there are regimes in which they coexist. 相似文献
49.
Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions 总被引:2,自引:0,他引:2
Carl Holt Deborah McPhail Ian Nevison Tommy Nylander Jeanette Otte Richard H. Ipsen Rogert Bauer Lars gendal Kees Olieman Kees G. de Kruif Joëlle Léonil Daniel Mollé Gwénaële Henry Jean Louis Maubois M. Dolores Pérez Pilar Puyol Miguel Calvo Stella M. Bury George Kontopidis Iain McNae Lindsay Sawyer Laura Ragona Lucia Zetta Henriette Molinari Bert Klarenbeek Margrethe J. Jonkman Jacques Moulin & Dereck Chatterton 《International Journal of Food Science & Technology》1999,34(5-6):543-556
Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999). 相似文献
50.
Sergey Tkachev Miguel Monteiro João Santos Ernesto Placidi Mohamed Ben Hassine Pedro Marques Paulo Ferreira Pedro Alpuim Andrea Capasso 《Advanced functional materials》2021,31(33):2103287
Graphene-based materials have attracted significant attention in many technological fields, but scaling up graphene-based technologies still faces substantial challenges. High-throughput top-down methods generally require hazardous, toxic, and high-boiling-point solvents. Here, an efficient and inexpensive strategy is proposed to produce graphene dispersions by liquid-phase exfoliation (LPE) through a combination of shear-mixing (SM) and tip sonication (TS) techniques, yielding highly concentrated graphene inks compatible with spray coating. The quality of graphene flakes (e.g., lateral size and thickness) and their concentration in the dispersions are compared using different spectroscopic and microscopy techniques. Several approaches (individual SM and TS, and their combination) are tested in three solvents (N-methyl-2-pyrrolidone, dimethylformamide, and cyrene). Interestingly, the combination of SM and TS in cyrene yields high-quality graphene dispersions, overcoming the environmental issues linked to the other two solvents. Starting from the cyrene dispersion, a graphene-based ink is prepared to spray-coat flexible electrodes and assemble a touch screen prototype. The electrodes feature a low sheet resistance (290 Ω □−1) and high optical transmittance (78%), which provide the prototype with a high signal-to-noise ratio (14 dB) and multi-touch functionality (up to four simultaneous touches). These results illustrate a potential pathway toward the integration of LPE-graphene in commercial flexible electronics. 相似文献