sinopseV3n3.pdf - FEEC - Unicamp

and enhance the critical current density values, especially for a
sample with 0.5%Ni. A negligible amount of Ni diffuses inside
the MgB2 grains, thus having a small effect on the transition
temperature, which remains around 37.5 K.
Optical Amplitude Modulation Extinction by a
Deep Saturated Ultra-Long Semiconductor
Optical Amplifier
Napoleão S. Ribeiro, André L. R. Cavacalcante, Cristiano M.
Gallep, Evandro Conforti
Optics Express
ISSN: 1094-4087 v:18 n:26 Dec-2010 pp:27298-27305
doi: 10.1364/OE.18.027298
Abstract: The recovery of an optical carrier with the deletion
of its amplitude modulation is introduced using a deeply
saturated ultra-long semiconductor optical amplifier (UL-SOA).
The experimental results were achieved for input signal bit
rates up to 12.5 Gbps with high extinction ratio (up to 13.9 dB).
The influence of parameters such as UL-SOA bias current,
optical bandwidth, signal input power, modulation depth and
bit rate are analyzed including the carrier spectral broadening
effects due to the self-phase modulation effect.
Tridimensional Yagi antenna: shaping radiation
pattern with a non-planar array
Juliano Rodrigues Brianeze, Arismar Cerqueira Sodre Jr.,
Hugo Enrique Hernández Figueroa
IET Microwaves, Antennas & Propagation
ISSN: 1751-8725 v:4 n:9 Sep-2010 pp:1434-1441
doi: 10.1049/iet-map.2009.0480
Abstract: This work presents the concept and development of
the tridimensional Yagi antenna, which is a novel type of Yagi
antenna operating in P band. It is idealised from two other types
of Yagi antennas: Quasi-Yagi and Yagi-Uda. The resultant
antenna is based on a microstrip balun, as in the first, and its
driver and directors are made from metal tubes, as in the
second, both integrated to a reflecting plane. The key point of
this new antenna model is its asymmetric and reconfigurable
radiation pattern and therefore the possibility of a high rejection
between sectors in a plane. This feature was accomplished with
the new concept of progressive rotation of directors around the
driver. The authors present a design methodology to adjust
return loss and radiation pattern characteristics. The final
prototype presents 9.4 dB gain at 450 MHz and 47% bandwidth
centred at 425 MHz.
Keywords: tridimensional Yagi antenna, radiation
pattern, nonplanar antenna array, quasi Yagi antenna,
Yagi-Uda antenna, microstrip balun, gain 9.4 dB,
frequency 450 MHz, bandwidth 425 MHz
Biomedical Engineering
Functional antagonism of β-adrenoceptor
subtypes in the catecholamine-induced
automatism in rat myocardium
D.C. Boer, José Wilson Magalhães Bassani, Rosana Almada
Bassani
British Journal of Pharmacology
ISSN: 1476-5381
Nov-2010
doi: 10.1111/j.1476-5381.2010.01121.x.
Abstract: Background and purpose. Myocardial automatism
and arrhythmias may ensue during strong sympathetic
stimulation. We sought to investigate the relevant types of
adrenoceptor, as well as the role of phosphodiesterase (PDE)
activity, in the production of catecholaminergic automatism in
atrial and ventricular rat myocardium. Experimental approach.
The effects of adrenoceptor agonists on the rate of spontaneous
contractions (automatic response) and the amplitude of
electrically-evoked contractions (inotropic response) were
determined in left atria and ventricular myocytes isolated from
Wistar rats. Key results. Catecholaminergic automatism was
Ca(2+) -dependent, as it required a functional sarcoplasmic
reticulum to be exhibited. Although both á- and â adrenoceptor
activation caused inotropic stimulation, only β(1) adrenoceptors
seemed to mediate the induction of spontaneous activity.
Catecholaminergic automatism was enhanced and suppressed
by β(2) adrenoceptor blockade and stimulation, respectively.
Inhibition of either PDE3 or PDE4 (by milrinone and rolipram,
respectively) potentiated the automatic response of myocytes to
catecholamines. However, only rolipram abolished the
attenuation of automatism produced by β(2) adrenoceptor
stimulation. Conclusions and Implications. α- and β(2) -
adrenoceptors do not seem to be involved in the mediation of
catecholaminergic stimulation of spontaneous activity in atrial
and ventricular myocardium. However, a functional antagonism
of β(1) - and β(2) adrenoceptor activation was identified, the
former mediating catecholaminergic myocardial automatism,
and the latter attenuating this effect. Results suggest that
hydrolysis of cAMP by PDE4 is involved in the protective
effect mediated by β(2) adrenoceptor stimulation.
Keywords: arrhythmias, PDE, β(2) adrenoceptors
Wrist Movement Characterization by
Mechanomyography Technique
Eduardo Mendonça Scheeren, Eddy Krueger, Guilherme
Nogueira, Percy Nohama, Vera Lucia da Silveira Nantes
Button
Journal of Medical and Biological Engineering
ISSN: 1609-0985 v:30 n:6 Sep-2010 pp:373-380
doi: 10.5405/jmbe.757
Abstract: Mechanomyography (MMG) monitors the
oscillations caused by muscle contraction. Muscle contractions
generate motion artifacts which can significantly affect signal
processing of MMG. In order to avoid such interference during
signal analysis, one can respect a time delay (TD) after the
onset of contraction (OC). This study aimed to identify wrist
antagonist movements from signals recorded with MMG
sensors. The distinction was performed after evaluating the
correlation between windows of interest in signals between 0.2
s after OC (0.2 AOC) and 1.0 s after OC (1.0 AOC). Twelve
volunteers performed concentric wrist contractions: flexion and
ulnar deviation (inner side) and extension and radial deviation
(outer side). Two triaxial MMG sensors were placed on the
inner and outer sides of the forearm. The features used in the
analysis of MMG signals were root mean square (RMS),
number of zero-crossings, peak counting and the multiplication
RMS times number of zero-crossings (RZ). Two analysis
window lengths (0.25 s and 0.5 s) were evaluated. ANOVA
tests indicated that flexion was different from extension, ulnar
and radial deviation, and radial deviation was different from
ulnar deviation and flexion. The results suggest that it is
possible to identify whether the movements are antagonistic
and to distinguish movements from the same side. There were
strong correlations between the acquired signals and TD,
mainly the devised RZ feature (0.81~0.95). This study
proposed an approach to determine whether triaxial MMG
features can be used for motor prosthesis control. The triaxial
modulus presented strong correlations for all movements and
can be useful in future applications.
Keywords: TAccelerometer, Prosthesis control, Upper
limb
Computer Engineering
Watershed from propagated markers: An
interactive method to morphological object
segmentation in image sequences
Franklin César Flores, Roberto de Alencar Lotufo
Image and Vision Computing
ISSN: 0262-8856 v:28 n:11 Nov-2010 pp:1491-1514
doi: 10.1016/j.imavis.2009.06.015
Abstract: In this paper, it is introduced an interactive method
to object segmentation in image sequences, by combining
56 Sinopse da FEEC