Time filter

Source Type

Madrid, Spain

Psychogiou D.,Purdue University | Gomez-Garcia R.,University of Alcal | Peroulis D.,Purdue University
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2016

This brief focuses on the radio frequency (RF) design of novel high-quality-factor (Q) reflective-type bandstop filters (BSFs) with narrow bandwidth (BW), small physical size, and large stopband attenuation levels. They are realized by merging acoustic-wave-lumped-element resonators (AWLRs) and lumped-element impedance inverters in a single filter architecture. In this manner, deep stopband notches that correspond to resonators with effective quality factors (Qeff) on the order of 1000 are created. Furthermore, the obtained rejection bands exhibit fractional BWs that are no longer restricted by the electromechanical coupling coefficient kt2 of the constituent acoustic wave (AW) resonators as opposed to the traditional all-AW filters. Experimental prototypes of first- and third-order frequency-static BSFs were built and tested at 418 MHz to validate the proposed concept. Measured stopbands with 3-dB BWs from 0.2 to 0.5 MHz, maximum stopband attenuation in the range of 15-43 dB, and passband insertion loss between 0.37 and 1.6 dB are reported. Moreover, an electronically switchable BSF with dynamic notch allocation is presented as a practical demonstrator device for switchable RF-interference suppression. A design methodology that relates to coupled-resonator filter formalism is also addressed to facilitate the systematic theoretical synthesis of the engineered AWLR-based reflective-type BSFs. © 2004-2012 IEEE.

Buendia R.,University of Boras | Gil-Pita R.,University of Alcal | Seoane F.,University of Boras | Seoane F.,KTH Royal Institute of Technology
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2011

Applications based on measurements of Electrical Bioimpedance Spectrocopy (EBIS) analysis are proliferating. The most spread and known application of EBIS is the non-invasive assessment of body composition. Fitting to the Cole function to obtain the Cole parameters, R 0 and R, is the core of the EBIS analysis to obtain the body fluid distribution. An accurate estimation of the Cole parameters is essential for the Body Composition Assessment (BCA) and the estimation process depends on several factors. One of them is the upper frequency limit used for the estimation and the other is the number of measured frequencies in the measurement frequency range. Both of them impose requirements on the measurement hardware, influencing largely in the complexity of the bioimpedance spectrometer. In this work an analysis of the error obtained when estimating the Cole parameters with several frequency ranges and different number of frequencies has been performed. The study has been done on synthetic EBIS data obtained from experimental Total Right Side (TRS) measurements. The results suggest that accurate estimations of R 0 and R for BCA measurements can be achieved using much narrower frequency ranges and quite fewer frequencies than electrical bioimpedance spectrometers commercially available nowadays do. © 2011 IEEE.

Gomez-Garcia R.,University of Alcal | Sanchez-Renedo M.,University of Alcal
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

A new class of microwave dual-band bandpass planar filter is reported. It uses an original generalized branch-line hybrid topology devised here, operating as dual-passband transversal filtering section. This type of filter network, under feedforward signal-interaction concepts, enables dual-band bandpass filtering actions with transmission zeros to be generated. Some design formulas and guidelines helping to synthesize the proposed dual-passband transversal filtering section are given. Furthermore, to prove its practical viability, theoretical, simulated and experimental results of two manufactured sharp-rejection dual-band bandpass microstrip filter prototypes are shown. © 2010 IEEE.

Prez-Rico C.,University Hospital Principe Of Asturias | Pascual G.,University of Alcal | Pascual G.,CIBER ISCIII | Sotomayor S.,University of Alcal | And 8 more authors.
American Journal of Ophthalmology | Year: 2011

Purpose To evaluate possible changes in the collagen and elastic components of the subepithelial connective tissue of human pterygium. Design Immunohistochemical study. Methods Immunohistochemical staining using antitropoelastin, anti-fibulin-2, and anti-fibulin-3 antibodies was performed in 10 normal conjunctival and 20 pterygium specimens. Masson trichome staining also was performed to study subepithelial connective tissue. Sirius red staining was used to identify collagen type I and III components. Tropoelastin, fibulin-2, and fibulin-3 messenger ribonucleic acid (mRNA) expressions were analyzed in 9 conjunctival and 12 pterygium specimens by quantitative real-time polymerase chain reaction assay. Results The subepithelial connective tissue and vessels were more predominant in pterygium compared with the normal conjunctival tissue. Amorphous subepithelial zones were observed in the areas of the pterygium tissue, but not in normal conjunctiva. Increased tropoelastin staining was seen in the pterygium tissue with areas of degenerative changes or immature formation of elastic fibers, as well an increase in tropoelastin mRNA, in contrast with fibulin-2 and fibulin-3 messenger levels. Fibulin-2 and fibulin-3 expression was colocalized in the subepithelial connective tissue and was distributed along blood and lymphatic vessels. Collagen type III, an immature form of collagen, was increased in the pathologic samples in association with a tissue remodeling process. Conclusions Elastin metabolism is dysregulated in the pathogenesis of human pterygium with tropoelastin, fibulin-2, and fibulin-3 overexpression in the subepithelial connective tissue.

del Campo E.M.,University of Alcal | Catala S.,University of Valencia | Gimeno J.,University of Valencia | del Hoyo A.,University of Alcal | And 4 more authors.
FEMS Microbiology Ecology | Year: 2013

The epiphytic lichen Ramalina farinacea is distributed throughout the northern hemisphere in which the same two algal Trebouxia species (provisionally named TR1 and TR9) coexist in every thallus. Ramalina farinacea symbionts were characterized based on the two fungal nuclear loci (nrITS and rpb2) along with the primary and secondary structures of nrITS from each Trebouxia species in the Iberian Peninsula and Canary Islands. The results indicated a noticeable genetic differentiation between mycobionts from these two geographic areas and also suggested concerted changes in the three partners of a lichen symbiosis toward two clearly distinguishable 'holobiont' lineages. Modeling of ITS2 RNA secondary structures suggested their temperature sensitivity in TR1 but not in TR9, which was consistent with the observed superior physiological performance of TR9 phycobionts under relatively high temperatures. Both TR1 and TR9 phycobionts have been also found in a variety of taxonomically distinct lichens with a preferably Mediterranean distribution, being TR1 much more widespread than TR9. Our observations support a model in which ecological diversification and speciation of lichen symbionts in different habitats could include a transient phase consisting of associations with more than one photobiont in individual thalli. Such diversification is likely to be promoted by different physiological backgrounds. © 2012 Federation of European Microbiological Societies.

Discover hidden collaborations