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A GENERAL SAMPLING THEORY FOR NONIDEAL ACQUISITION DEVICES

IEEE TRANSACTIONS ON SIGNAL PROCESSING 1994年第11期42卷 2915-2925页

作者： UNSER, M ALDROUBI, A Biomedical Engineering and Instrumentation Program National Center for Research Resources National Institutes of Health DHHS Bethesda MD USA

We first describe the general class of approximation spaces generated by translation of a function rho(x), and provide a full characterization of their basis functions. We then present a general sampling theorem for computing the approximation of signals in these subspaces based on a simple consistency principle. The theory puts no restrictions on the system input which can be an arbitrary finite energy signal;bandlimitedness is not required. In contrast to previous approaches, this formulation allows for an independent specification of the sampling (analysis) and approximation (synthesis) spaces. In particular, when both spaces are identical, the theorem provides a simple procedure for obtaining the least squares approximation of a signal. We discuss the properties of this new sampling procedure and present some examples of applications involving bandlimited, and polynomial spline signal representations. We also define a spectral coherence function that measures the ''similarity'' between the sampling and approximation spaces, and derive a relative performance bound for the comparison with the least squares solution.

关键词： Sampling methods Least squares approximation Filters Polynomials Spline Signal sampling Interpolation Signal representations Kernel Signal resolution

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Corneal thermal damage quantification from birefringence image analysis using morphological filtering 5

Corneal thermal damage quantification from birefringence ima...

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Laser-Tissue Interaction V;and Ultraviolet Radiation Hazards 1994

作者： McMurray, Tom Smithpeter, Cohn Welch, A.J. Rylander, H.G. Pearce, John A. University of Texas at Austin Biomedical Engineering Program AustinTX United States

Decreased cornea! collagen birefringence in transmission polarizing microscopy is an observable quantitative measure of degree of tissue damage. A damage assessment algorithm based on monochrome tissue images exhibiting decreased birefringence is presented identifying image regions with designated damage values. Initially, several video frames of the microscopic tissue image are time averaged to reduce additive noise components, and an additional multiplicative correction for optical nonuniformities is performed. Subsequently, linear scaling improves the low contrast of the birefringence image by increasing the image value set to the standard 8-bit range of integers in the interval [0,255]. Finally, morphological erosion employing a 5 x 5 pixel template reduces impulsive bright tissue artifacts. Formal damage quantification consists of a 25 x 25 pixel template mean filtering of the image, followed by background subtraction and scaling. This produces the components required for the damage computation according to the volume fraction kinetic damage model. In this investigation, the corneal damage region resembles an edge. Therefore, standard edge detection algorithms applied to the eroded image are cornpared to the damage region identified by this algorithm. This damage quantification algorithm provides significantly superior edge delineation relative to Roberts, Sobel, Frei-Chen, Laplacian of Gaussian, and Blur-Minimum and Erosion Residue morphological edge detection algorithms. © 1994 Proceedings of SPIE - The International Society for Optical engineering. All rights reserved.

关键词： Birefringence

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CORRELATIONAL ACCUMULATION AS A METHOD FOR SIGNAL RESTORATION

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SIGNAL PROCESSING 1994年第1-2期39卷 89-106页

作者： YAROSLAVSKY, L EDEN, M Biomedical Engineering and Instrumentation Program Building 13 Room 3W13 National Institutes of Health 900 Rockvulle Pike Bethesda MD 20892 USA

This work analyses the method of correlational accumulation (averaging) of a set of multiple copies of a signal from the same object arbitrarily displaced with relation to one another and observed in a mixture with additive signal independent sensor noise in which the signal displacements are measured by localization of maximum of the signal cross-correlation function. Three main problems are addressed and investigated both analytically and by computer simulation: optimality of the correlational accumulation method, signal distortions which originate from the signal registration errors and noise reduction capability of the correlational accumulation as a function of signal-to-noise ratio in the observed signal-plus-noise realizations.

关键词： CORRELATION LOCALIZATION ACCURACY SIGNAL AVERAGING SIGNAL REGISTRATION SIGNAL RESTORATION

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Development of a direct systolic cardiac augmentation device

Development of a direct systolic cardiac augmentation device

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Proceedings of the 31st Annual Rocky Mountain Bioengineering Symposium (RMBS)

作者： Frake, B.C. Young, D.F. Kudej, R.K. Biomedical Engineering Program Iowa State University Ames IA 50011 United States

A direct systolic cardiac augmentation device, called a heart Cuff, has been developed. The device is designed to be placed around a 'weakened' heart to improve cardiac function.

ISBN: (纸本)1556174985

A direct systolic cardiac augmentation device, called a heart Cuff, has been developed. The device is designed to be placed around a 'weakened' heart to improve cardiac function.

关键词： Cardiovascular system

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FIR APPROXIMATIONS OF INVERSE FILTERS AND PERFECT RECONSTRUCTION FILTER BANKS

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SIGNAL PROCESSING 1994年第2期36卷 163-174页

作者： UNSER, M EDEN, M Biomedical Engineering and Instrumentation Program Bldg 13 Room 3W13 National Center for Research Resources National Institutes of Health Bethesda MD 20892 USA

This paper first describes an algorithm that finds the approximate finite impulse response (FIR) inverse of an FIR filter by minimizing the inversion (or reconstruction) error constrained to zero-bias. The generalization of the inverse filtering problem in the two channel case is the design of perfect reconstruction filter banks that use critical sampling. These considerations lead to the derivation of an algorithm that provides a minimum error and unbiased FIR/FIR approximation of a perfect reconstruction IIR/FIR (or FIR/IIR) filter bank. The one-channel algorithm is illustrated with the design of an FIR filter to compute the B-spline coefficients for cubic spline signal interpolation. The two-channel algorithm is applied to the design of a FIR/FIR filter bank that implements the cubic B-spline wavelet transform. Finally, we consider a modification of this technique for the design of modulated-filter banks, which are better suited for subband coding.

关键词： LEAST-SQUARES DESIGN INVERSE FILTER PERFECT RECONSTRUCTION FILLER BANK WAVELET TRANSFORM SPLINE FUNCTIONS CUBIC SPLINES B-SPLINES GABOR TRANSFORM INTERPOLATION

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Abstract

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Pflügers Archiv 1996年第6期431卷 R322-R356页

作者： L. J. Andries S. U. Sys A. L. Meulemans J. A. J. Schuurkes B. Vanheel J. Van de Voorde P. De Smet J. Li W. Van Driessche B. Flamion S. Foulon M. Abramow P. Calders W. Eechaute E. Lacroix I. Weyne D. Hoeben C. Burvenich P. Fransen D. Van Bedaf M. Demolder R. Ouedraogo P. Lebrun A. Herchuelz M. -H. Antoine S. Vandenput D. Votion N. Anciaux D. H. Duvivier T. Art P. Lekeux Y. Ghafir M. Geurts E. Hermans J. -M. Maloteaux B. Perrad B. Noel F. Lagache J. L. Bister R. Paquay G. Derycke M. A. Vandermeir S. de Brouwer C. -A. Porret N. Stergiopulos J. -J. Meister M. Verbeke N. Lameire N. M. De Clerck J. De Schuytter J. Tytgato G. Buyse J. Eggermont G. Droogmans B. Nilius P. Daenens S. Salomone O. Feron C. Dessy N. Morel T. Godfraind A. M. Aloisi P. Sacerdote L. Lodi G. Carli C. Carobi G. Garinei U. C. Miniaci P. Scotto M. Sabatino P. Sardo L. Iurato V. La Grutta M. A. Bagni G. Cecchi E. Cecchini F. Colomo P. Garzella R. Bottinelli S. D. H. Harridge M. Canepari C. Reggiani Saltin Reggiani D. Bambagioni G. Fanò G, Menchetti P. Danieli-Betto A. Esposito R. Betto A. Megighian M. Midrio D. Danieli Betto C. Orizio D. Liberati C. Locatelli D. De Grandis A. Veicsteinas D. Angoli D. Delia E. Wanke M. Bramucci A. Miano L. Quassinti E. Maccari O. Murri D. Amici G. Cibelli S. Jüngling S. Schoch H. H. Gerdest G. Thiel I. Demori C. Bottazzi A. Voci E. Fugassa A. Barreca F. Minuto G. Gallo S. Fulle S. Belia G. Menchetti M. Cacchio G. Gastaldi U. Laforenza G. Ferrari G. Rindi M. G. Doni E. Padoin O. Residori M. Cesaro L. Toma A. Rubini F Mutinelli L. Paulesu R. Romagnolie M. Cintorino P. Pippia M. A. Meloni L. Sciola A. Spano M. Cogoli-Greuter A. Cogoli A. Sardini G. M. Mintenig M. A. Valverde F. V. Sepùlveda D. R. Gill S. C. Hyde C. F. Higgins P. A. McNaughton A. Spena M. T. Arcuri S. Bonofiglio R. Chimenti C. Covello T. De Cicco S. Mazzulla G. Martino A. Tottene A. Moretti D. Pietrobon M. C. Baccari F. Calamai G. Staderini E. Cova R. Marelli P. Sommi U. Ventura A. M. Lombardi R. Fabris C. Pagano G. Federspil R. Vettor R. Mancinelli P. To Laboratory of Physiology RUCA University of Antwerp Belgium Dept. of Gastroint. Pharmacol. Janssen Research Foundation Beerse Belgium Department of Physiology and Physipathology University of Gent De Pintelaan 185 Gent Belgium Laboratory of Physiology K. U. Leuven Leuven Belgium Laboratory of Pathophysiology University of Bruxelles (ULB) Brussels Belgium Laboratory of Normal and Pathological Physiology University of Gent Belgium Department of Physiology Biochemistry and Biometrics Faculty of Veterinary Medicine University of Ghent Merelbeke Belgium Laboratory of Physiology University of Antwerp (RUCA) Antwerp Belgium Lab. de Pharmacodynamie et de Thérapeutique Université Libre de Bruxelles Bruxelles Belgique Laboratory for Functional Investigation Faculty of Veterinary Medicine University of Liége Liège Belgium Laboratory for Functional Investigation Faculty of Veterinary Medicine University of Liège Liège Belgium Laboratory of Pharmacology Catholic University of Louvain Brussels Laboratoire de Physiologie Animale FUNDP Namur Laboratory of animal Physiology Facultés universitaires Notre-Dame de la Paix Namur Belgium Biomedical Engineering Laboratory Swiss Federal Institute of Technology Lausanne Switzerland RUCA University of Antwerp Antwerp Belgium Laboratory of Physiology Laboratory of Toxicology University of Leuven Leuven Belgium Laboratoire de Pharmacologie Université Catholique de Louvain Bruxelles Belgium Istituto di Fisiologia Umana Università degli Studi Siena Dipartimento di Farmacologia Università degli Studi di Milano Milano Istituto di Fisiologia Umana Università di Perugia Perugia Dipartimento di Medicina Sperimentale Università di Reggio Calabria Laboratorio di Fisiologia Umana Catanzaro Istituto di Fisiologia umana Palermo Dipartimento di Scienze Fisiologiche Università di Firenze Firenze Dipartimento Biologia Cellulare e Molecolare (sez. Fisiologia e Biofisica) Università di Perugia Perugia Istituto di Fisiologia Umana Univer

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A Network Thermodynamic Model of Kidney Perfusion

引用

IFAC Proceedings Volumes 1994年第1期27卷 289-290页

作者： Charles A. Lachenbruch Kenneth R. Diller Department of Mechanical Engineering Biomedical Engineering Program The University of Texas at Austin Austin Texas

A network thermodynamic model has been devised to describe the coupled movement of water and glycerol molecules within the kidney during perfusion with solutions of time-varying glycerol and impermeant comcentrations. Both flows are governed by a combination of the individual osmotic potential differences between compartments, the viscoelastic behavior of the tissue, and the momentum transferred between the two flows. The system is modelled using the bond graph technique and simulated with the ENPORT7 package (Rosencode Associates, 1993).

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RELATION BETWEEN FLUORESCENCE-SPECTRA OF DILUTE AND TURBID SAMPLES

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APPLIED OPTICS 1994年第3期33卷 414-423页

作者： DURKIN, AJ JAIKUMAR, S RAMANUJAM, N RICHARDSKORTUM, R The authors are with the Biomedical Engineering Program Engineering Science Building The University of Texas at Austin Austin Texas 78712-1084.

We present a method to extend rank-annihilation-factor analysis (RAFA) for the analysis of fluorescence from homogeneous turbid samples. The method is based on a fundamental relationship between the fluorescence of a dilute solution and that of a turbid solution. We have derived this relationship, known as the transfer function, for turbid materials using the two-flux Kubelka-Munk theory. The method is tested with spectroscopic data from optically thin and turbid samples of the media of a human aorta. At 450-nm excitation, agreement between the measured and predicted dilute-solution fluorescence spectra is within 5% at all emission wavelengths;at 340-nm excitation, agreement is within 20% at all wavelengths, with some residual Soret-band absorption. The simulations presented indicate that the transfer function is markedly more sensitive to absorption than to scattering properties.

关键词： FLUORESCENCE SCATTERING TURBID KUBELKA-MUNK THEORY TISSUE

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LIGHT DOSIMETRY - EFFECTS OF DEHYDRATION AND THERMAL-DAMAGE ON THE OPTICAL-PROPERTIES OF THE HUMAN AORTA (VOL 32, PG 477, 1993)

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APPLIED OPTICS 1994年第16期33卷 3571-3571页

作者： CILESIZ, I WELCH, AJ []The authors are with the Biomedical Engineering Program The University of Texas at Austin 639 Engineering Science Building Austin Texas 78712-1084.

No abstract available.

关键词： Optical properties Reflection Scattering Thermal effects Tissue optical properties

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Monitoring of blood gases during prolonged experimental cardiopulmonary bypass and their relationship to brain pH, PO2, and PCO2

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ASAIO Journal 1994年第3期40卷 M344-M350页

作者： Briceno, J.C. Runge, T.M. Biomedical Engineering Program University of Texas Austin TX 78712 United States

Eight adult goats underwent 5 hr of normothermic cardiopulmonary bypass (CPB) with pulsatile (n = 3) and nonpulsatile flow (n = 5). PaCO2 was maintained at 30-40 mmHg and blood flow rate at 50 ml/min/kg. Brain tissue pH, PO2, and PCO2, arterial and venous blood gases, and other systemic variables were monitored. No significant differences in brain electrochemistrybetween pulsatile and nonpulsatile perfusion were observed owing to the large variability of the results and the small number of experiments. The overall data for brain tissue pH, PO2, and PCO2 were analyzed and compared to the results of arterial and venous pH, PO2, and PCO2. Brain acidosis developed at the onset of bypass, and the values for brain tissue pH dissociated from those of blood pH, suggesting that hemodilution and the initial body response to CPB are involved in its development. Brain hypercapnia also developed during CPB, the values of brain tissue PCO2 dissociated from those of blood PCO2, and brain hypercapnia appears to be secondary to brain acidosis. Brain tissue PO2 closely followed the values of PvO2, suggesting that PvO2 can be an indicator of brain tissue PO2 during normothermic CPB and must be monitored during the procedure. Brain tissue acidosis is evidently related to neurologic dysfunction after CPB, and must be addressed. Replacement of the priming solution with whole blood or artificial blood, reduction of the priming volume, and application of vigorous pulsatile flow appear feasible interventions to mitigate brain tissue acidosis during CPB.

关键词： Blood gas analysis

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