2015
Authors
Pereira, T; Correia, C; Cardoso, J;
Publication
Journal of Medical and Biological Engineering
Abstract
The great incidence of cardiovascular (CV) diseases in the world spurs the search for new solutions to enable an early detection of pathological processes and provides more precise diagnosis based in multi-parameters assessment. The pulse wave velocity (PWV) is considered one of the most important clinical parameters for evaluate the CV risk, vascular adaptation, and therapeutic efficacy. Several studies were dedicated to find the relationship between PWV measurement and pathological status in different diseases, and proved the relevance of this parameter. The commercial devices dedicate to PWV estimation make a regional assessment (measured between two vessels), however a local measurement is more precise evaluation of artery condition, taking into account the differences in the structure of arteries. Moreover, the current devices present some limitations due to the contact nature. Emerging trends in CV monitoring are moving away from more invasive technologies to non-invasive and non-contact solutions. The great challenge is to explore the new instrumental solutions that allow the PWV assessment with fewer approximations for an accurately evaluation and relatively inexpensive techniques in order to be used in the clinical routine. © The Author(s) 2015.
2015
Authors
Pereira, T; Sanches, R; Reis, P; Pego, J; Simoes, R;
Publication
2015 IEEE 4TH PORTUGUESE MEETING ON BIOENGINEERING (ENBENG)
Abstract
Blood pressure (BP) determination is a fundamental parameter in cardiovascular assessment. The gold standard method to measure BP is based on the inflatable arm cuff, however has several disadvantages for continuous monitoring. New techniques were developed to overcome these limitations using correlations between the pulse transit time (PTT) and BP. This work draws attention to the PTT rationale using several methods. In order to determine the PTT, an electrocardiogram (ECG) was used combined with multiple photoplethysmography (PPG) sensors applied to different arm locations, these signals were acquired with a bioPLUX device. The Ultrassound system (SonoSite Edge) was used to measure the artery diameter. As reference, BP was measured using a cuff- based sphygmomanometric device. Measurements were performed in a study population of 36 volunteers. The correlation coefficient for DBP determined and DBP measured was r = 0,689. The results suggest PTT deduced from different locations can be used to measure BP.
2015
Authors
Pereira, T; Correia, C; Cardoso, J;
Publication
JOURNAL OF MEDICAL AND BIOLOGICAL ENGINEERING
Abstract
The great incidence of cardiovascular (CV) diseases in the world spurs the search for new solutions to enable an early detection of pathological processes and provides more precise diagnosis based in multi-parameters assessment. The pulse wave velocity (PWV) is considered one of the most important clinical parameters for evaluate the CV risk, vascular adaptation, and therapeutic efficacy. Several studies were dedicated to find the relationship between PWV measurement and pathological status in different diseases, and proved the relevance of this parameter. The commercial devices dedicate to PWV estimation make a regional assessment (measured between two vessels), however a local measurement is more precise evaluation of artery condition, taking into account the differences in the structure of arteries. Moreover, the current devices present some limitations due to the contact nature. Emerging trends in CV monitoring are moving away from more invasive technologies to non-invasive and non-contact solutions. The great challenge is to explore the new instrumental solutions that allow the PWV assessment with fewer approximations for an accurately evaluation and relatively inexpensive techniques in order to be used in the clinical routine.
2015
Authors
Pereira, T; Pereira, TS; Santos, H; Correia, C; Cardoso, J;
Publication
INTERNATIONAL JOURNAL OF CARDIOLOGY
Abstract
2015
Authors
Bharmal N.A.; Beltramo-Martin O.; Correia C.M.;
Publication
Optics InfoBase Conference Papers
Abstract
A novel technique to measure C2n and L0 in the atmosphere from anisokinetism in tip/tilt corrected images of star fields by fitting parameter-based PSF models, enabling a low-complexity 24×7 capability.
2015
Authors
Bond C.Z.; Correia C.; Teixeira J.; Sauvage J.F.; Véran J.P.; Fusco T.;
Publication
Adaptive Optics for Extremely Large Telescopes 4 - Conference Proceedings
Abstract
The discrete sampling of a wave-front using a Shack-Hartmann sensor limits the maximum spatial frequency we can measure and impacts sensitivity to frequencies at the high end of the correction band due to aliasing. Here we present Wiener filters for wave-front reconstruction in the spatial-frequency domain, ideally suited for systems with a high number of degrees of freedom. We develop a theoretical anti-aliasing (AA) Wiener filter that optimally takes into account high-order wave-front terms folded in-band during the sensing (i.e., discrete sampling) process. We present Monte-Carlo simulation results for residual wave-fronts and propagated noise and compare to standard reconstruction techniques (in the spatial domain). To cope with finite telescope aperture we've developed and optimised a Gerchberg-Saxton like iterative-algorithm that provides superior performance.
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