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14th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 1992

作者： De Sá, A.M.F.L. Miranda Simpson, D.M. Infantosi, A.F.C. Biomedical Engineering Program COPPE Federal University of Rio de Janeiro CP. 68510 Rio de Janeiro21945 Brazil

ISBN: (纸本)0780307852

Coherence has been used to study the dependence between EEG derivations as a function of frequency. In order bto arrive at meaningful conclusions the statistics of the estimates must be known and are investigated in this paper - since the literature is rather confusing in this respect. The work is based on simulations with random signals and comparison with the values given in the literature. © 1992 IEEE.

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Decision support system to assist mechanical ventilation in the adult respiratory distress syndrome

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INTERNATIONAL JOURNAL OF CLINICAL MONITORING AND COMPUTING 1997年第2期14卷 73-81页

作者： Bottino, DA GiannellaNeto, A David, CMN Melo, MFV Biomedical Engineering Program Federal University of Rio de Janeiro Coppe/UFRJ Rio de Janeiro Brazil Dept. of Anesthesiology and Pain Management University of Texas Southwestern Medical Center Dallas USA

This paper presents a knowledge-based decision support system to assist mechanical ventilation in patients with the Adult Respiratory Distress Syndrome (DSSARDS). The knowledge base uses clinical algorithms developed from interviews and seminars with experts. The system contains 140 rules, applies backward chaining and was built on an IBM-PC compatible microcomputer. Clinical and physiological data and ventilator settings were used for suggestions of ventilatory support mode (VSMODE) and settings (MVSET) and for hemodynamic evaluation and therapy (HEMO). Success rates (s) and kappa coefficient (k) were used to measure agreement between DSSARDS and physicians at 4 decision steps related to: beginning of mechanical ventilation (FIRSTSET), VSMODE, MVSET and HEMO. DSSARDS prototype was evaluated in a development phase with 6 patients aged 48.6 +/- 15.9 years. Agreement results for 142 decision steps were: FIRSTSET k = 0.90, s = 0.93;VSMODE k = 0.76, s = 0.92;HEMO k = 0.58, s = 0.70, MVSET k = 0.86, s = 0.92 (p < 0.05 for all k). Improvements in the knowledge base were performed mainly in HEMO and VSMODE modules. The subsequent test phase studied 5 patients aged 54.8 +/- 11.0 years in a total of 900 decision steps. Results were: FIRSTSET k = 0.93, s = 0.95;VSMODE k = 0.93, s = 0.96;HEMO k = 0.97, s = 0.99, MVSET k = 0.96, s = 0.97 (p < 0.05 for all k). The results indicate significant agreement between DSSARDS and physicians for all decision steps. This suggests that DSSARDS may be used as a support for decision making and a training tool for mechanical ventilation in patients with the adult respiratory distress syndrome.

关键词： adult respiratory distress syndrome mechanical ventilators computer assisted decision making expert system

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Accurate calibration of pneumotacographs using a syringe and polynomial curve fitting 14

Accurate calibration of pneumotacographs using a syringe and...

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14th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 1992

作者： Neto, Antonio Giannella Do Vale, Marcio J. O. Melo, Marcos F. Vidal Biomedical Engineering Program COPPE Federal University of Rio de Janeiro PO Box 68510 Rio de Janeiro RJ21945 Brazil

ISBN: (纸本)0780307852

This work presents a simple, reliable and accurate calibration technique for pneumotacographs. It is based on a polynomial curve fitting which minimizes the calculated volume error for a set of injections of a calibrated syringe. In conditions similar to human spirometry the results meet the standards of the American Thoracic Society. © 1992 IEEE.

关键词： Syringes

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Construction of mixed covering arrays using a combination of simulated annealing and variable neighborhood search

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Electronic Notes in Discrete Mathematics 2015年 47卷 109-116页

作者： Rodriguez-Cristerna, Arturo Torres-Jimenez, Jose Gómez, W. Pereira, W.C.A. Technology Information Laboratory CINVESTAV Ciudad Victoria Tamaulipas Mexico Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

The construction of Mixed Covering Arrays (MCA) with the minimum number of rows has been a problem faced in different ways. This paper aims to construct near optimal MCAs through a novel approach based on Simulated Annealing (SA) and Variable Neighborhood Search (VNS). The solution quality of the proposed algorithm was measured by solving two benchmarks and the obtained results show a significant quality improvement over the results of previously reported metaheuristics. © 2014 Elsevier B.V.

关键词： Mixed covering arrays Simulated annealing Variable neighborhood search

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Influence of temperature on Mean Scattering Spacing estimation of in vitro bovine muscle

Influence of temperature on Mean Scattering Spacing estimati...

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作者： Cortela, G.A. Von Kruger, M.A. MacHado, C.B. Negreira, C.A. Pereira, W.C.A. Laboratorio de Acústica Ultrasónica UdelaR Montevideo Uruguay Biomedical Engineering Program COPPE/UFRJ Rio de Janeiro RJ Brazil

ISBN: (纸本)9781612849164

Periodicity of structures can be investigated with backscattered ultrasound, usually by applying spectral methods and estimating the Mean Scatterer Spacing (MSS). Biological tissues, such as skeletal muscle, or liver or trabecular bone, can present periodic or quasi-periodic structures. In this work it is studied the behavior of MSS with temperature and frequency for in vitro samples of bovine muscular tissues. MSS was obtained in the range of 37C to 43C, and between 1 MHz to 10.0 MHz Results show that, for the studied sample, MSS decreased with temperature for the muscle. It seems to be in agreement with the expected physiologic behavior of muscular fibers. Further complementary experiments are being envisaged. © 2011 IEEE.

关键词： Ultrasonics

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A frequency-compensated coded-excitation pulse to improve axial resolution of ultrasonic system

A frequency-compensated coded-excitation pulse to improve ax...

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2006 IEEE International Ultrasonics Symposium, IUS

作者： Barros, Álvaro Luiz Pereira Machado, João Carlos Da Costa-Félix, Rodrigo Pereira Barretto Biomedical Engineering Program COPPE Federal University of Rio de Janeiro Rio de Janeiro RJ Brazil Duque de Caxias RJ Brazil

ISBN: (纸本)1424402018

This work presents a method for coded excitation of ultrasound system using a compensated frequency modulation based on the spectral response of the echo from a flat reflector. The method provides an improvement of the overall range resolution of the ultrasound system comprising the pulse generator, impedance matching networks, receive amplifier and transmit/receive transducer. The method was tested in terms of the range resolution for the echo from a flat reflector and with the transducer of the ultrasound system excited with a linear frequency modulated coded excitation and with the proposed compensated frequency modulation coded excitation. The received echo was compressed using the cross-correlation technique and the width of the compressed echo-pulse envelope was around 1.02 and 0.85 μs for linear frequency modulation and compensated frequency modulation coded excitations, respectively. © 2006 IEEE.

关键词： Frequency modulation

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Evaluating periodicity of trabecular bone phantoms using ultrasound signals

Evaluating periodicity of trabecular bone phantoms using ult...

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Pan American Health Care Exchanges, PAHCE 2011 - Conference, Workshops, and Exhibits. Cooperation / Linkages: An Independent Forum for Patient Care and Technology Support

作者： Rosa, P.T.C.R. Matusin, D.P. Pereira, A.J.F. MacHado, C.B. Pereira, W.C.A. Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro RJ Brazil Laboratoire d'Imagerie Paramétrique Université Paris VI France

ISBN: (纸本)9781612849164

The aim of this work was to characterize the periodicity of a commercial available trabecular bone phantom with ultrasound (US) backscattered signals. Three US frequencies were applied (1.0, 2.25 and 5.0 MHz), and spectral analysis methods were used to estimate the mean scatterer spacing (MSS) of 100 signals/sample from five different samples. The results showed that it is possible to estimate the medium periodicity (trabecular spacings varying from 1.5 to 2.5 mm), and at higher frequencies the average MSS decreased, which is expected because of a higher spatial resolution (identification of the trabecular thickness periodicity). MSS values are in agreement with intertrabecular distances declared by the product supplier. © 2011 IEEE.

关键词： Ultrasonics

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NARX structures for non-invasive temperature estimation in non-homogeneous media

NARX structures for non-invasive temperature estimation in n...

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2007 IEEE International Symposium on Intelligent Signal Processing, WISP

作者： Teixeira, C.A. Pereira, W.C.A. Ruano, A.E. Graça Ruano, M. Centre for Intelligent Systems Faculty of Sciences and Technology University of Algarve PRT Portugal Biomedical Engineering Program-COPPE Federal University of Rio de Janeiro Brazil

ISBN: (纸本)142440830X

The safe and effective application of thermal therapies are limited by the existence of precise non-invasive temperature estimators. Such estimators would enable a correct power deposition on the region of interest by means of a correct instrumentation control. In multi-layered media, the temperature should be estimated at each layer and especially at the interfaces, where significant temperature changes should occur during therapy. In this work, a non-linear autoregressive structure with exogenous inputs (NARX) was applied to non-invasively estimate temperature in a multi-layered (non-homogeneous) medium, while submitted to physiotherapeutic ultrasound. The NARX structure is composed, by a static feed-forward radial basis functions neural network (RBFNN), with external dynamics induced by its inputs. The NARX structure parameters were optimized by means of a multi-objective genetic algorithm. The best attained models reached a maximum absolute error inferior to 0.5C (proposed threshold in hyperthermia/diathermia) at both the interface and inner layer points, at four radiation intensities. These models present also a small computational complexity as desired for real-time applications. To the best of ours knowledge this is the first non-invasive estimation approach in multi-layered media using ultrasound for both heating and estimation. ©2007 IEEE.

关键词： Ultrasonics

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In Vitro Degradation of Polydioxanone (PDO) Lifting Threads in Microfocused Ultrasound

In Vitro Degradation of Polydioxanone (PDO) Lifting Threads ...

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2024 Global Medical engineering Physics Exchanges/Pan American Health Care Exchanges, GMEPE/PAHCE 2024

作者： Silva, M.H.R. Raybolt, A. Pereira, W.C.A. Federal University of Rio de Janeiro Biomedical Engineering Program - Coppe RJ Brazil Federal University of Rio de Janeiro School of Dentistry RJ Brazil

ISBN: (纸本)9798350390490

Objective: Analyze the static degradation time of polydioxanone (PDO) threads with or without the association of microfocused ultrasound, which are techniques for aesthetic purposes. Materials and Methods: In vitro assays were conducted in isotonic solution using smooth polydioxanone (PDO) threads divided into 2 groups (n=3): FPL (Smooth Polydioxanone Thread) and FPLU (Smooth Polydioxanone Thread with Ultrasound). The FPLU group underwent microfocused ultrasound. Both groups endured the following analyses: UV spectroscopy Absorbance and Scanning Electron Microscopy (SEM). Results: Absorbance by UV spectroscopy: The concentration levels of molecules in the aliquots showed that at 8 days both FPL and FPLU groups exhibited absorbance levels of 0.0040 (mol-1/***-1) and 0.00585 (mol-1/***-1), respectively. At 30 days, these levels were 0.0799 (mol-1/***-1) and 0.0543 (mol-1/***-1). At 60 days, the FPLU group showed significant increase to 0.2039 (mol-1/***-1) compared to the FPL group at 0.1152 (mol-1/***-1) reaching a degradation peaks at 60 days. At 90 days, the FPL group presented 0.1299 (mol-1/***-1) and the FPLU group presented 0.2377 (mol-1/***-1). SEM: Morphological differences were observed in both groups. Conclusion: FPLU group showed higher absorbance over time. Microfocused ultrasound accelerated degradation time PDO threads, diminishing its functionality. © 2024 IEEE.

关键词： Ultrasonics

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Noninvasive cardiac output estimates during quiet respiration through partial CO2 rebreathing 14

Noninvasive cardiac output estimates during quiet respiratio...

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14th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 1992

作者： Melo, Marcos F. Vidal Abreu, Marcelo G. Giannella-Neto, Antonio Biomedical Engineering Program COPPE Federal University of Rio de Janeiro P.O. Box 68510 Rio de Janeiro RJ21945 Brazil

ISBN: (纸本)0780307852

A noninvasive technique to measure cardiac output in spontaneously breathing subjects is evaluated. It is based on a differential form of the Fick equation and a partial rebreathing maneuver. Corrections for experimental error and a new ventilatory maneuver are introduced to reduce variability. Results suggest that the technique may attain error performance compatible with the invasive thermodilution method. © 1992 IEEE.

关键词： Hemodynamics

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