We investigated the feasibility of obtaining body surface Laplacian maps (BSLMs) from unipolar electrocardiographic recordings in humans. The overall pattern of the BSLMs during ventricular depolarization is reproduci...
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We investigated the feasibility of obtaining body surface Laplacian maps (BSLMs) from unipolar electrocardiographic recordings in humans. The overall pattern of the BSLMs during ventricular depolarization is reproducible for subjects examined and for multiple sets of maps within a single subject. Right and left ventricular activities are well resolved in the BSLMs over the anterior chest as compared with body surface potential maps (BSPMs). Our experimental results demonstrate the feasibility of performing body surface Laplacian electrocardiographic mapping from potential recordings. The effects of measurement noise and electrode position uncertainty on the Laplacian derivation were also evaluated by computer simulation.
Tissue elasticity can be estimated from displacement and strain images acquired under controlled deformation. We extend this approach for coronary arteries, deformed and imaged by an integrated angioplasty balloon and...
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Tissue elasticity can be estimated from displacement and strain images acquired under controlled deformation. We extend this approach for coronary arteries, deformed and imaged by an integrated angioplasty balloon and ultrasonic imaging probe. Because the lumen cross section of a severely occluded artery is generally not circular, we have also developed a technique to perform all motion computations in the reference frame of the lumen's geometric center. This coordinate system is independent of the imaging catheter, and consequently referencing to this frame removes artifacts associated with probe motion within the balloon during deformation. Displacements and strains estimated by phase-sensitive correlation-based speckle tracking were used to distinguish arterial plaques in simulated coronary arteries of differing elastic moduli: hard, soft, and homogenous. We have also applied these methods to images of a homogeneous gelatin phantom collected with the integrated probe. The spatial dependence of these quantities shows good agreement with theoretically predicted values.
A capacitance humidity sensor is used as a test de- vice to characterize the performance of thirteen polyimide films in relative humidity sensing applications. This sensor has a multilayer, free-standing film construc...
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A capacitance humidity sensor is used as a test de- vice to characterize the performance of thirteen polyimide films in relative humidity sensing applications. This sensor has a multilayer, free-standing film construction. It consists of a humidity sensitive polyinfide dielectric core and conductive layers consisting of carbon filled polysul- fone on each side of the polyimide film to form a capacitor. Thirteen polyimide films, including commercial polyimides and films of novel chemistry, are investigated to determine the long term stability of sensors using the films exposed to 85'C/85% RH for a total of 28 days. Differences in film chemistry are used to interpret trends in the environmental stability of the films.
The characterization of microemboli located in whole blood is attempted by determining the Legendre coefficients of phase function from the scattered light distribution around the medium. In the radiative transport eq...
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The characterization of microemboli located in whole blood is attempted by determining the Legendre coefficients of phase function from the scattered light distribution around the medium. In the radiative transport equation, a microembolus is represented as a secondary source and assumed to have a spherical form and the first order transport approximate solution of the equation is used to describe the scattered intensity distribution. After the scattered intensities are determined at the surfaces of the medium, the orthogonal property of Legendre polynomial is used to extract the coefficients out of the intensities. From the obtained coefficients, the size and complex index of refraction of microemboli are determined.
Gas desorption from a field emitter array (FEA) cathode and phosphor screen anode in a flat panel display must be controlled so that outgassing products produced during display operation do not change cathode electron...
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Gas desorption from a field emitter array (FEA) cathode and phosphor screen anode in a flat panel display must be controlled so that outgassing products produced during display operation do not change cathode electron emission and degrade display performance and uniformity. In order to help understand such desorption processes and to help define pumping requirements in FEA displays, we have determined the major species outgassing from two phosphor screen-FEA cathode systems. The screens were made from YAG:Cr and ZnGa/sub 2/O/sub 4/, candidate materials for use as low voltage phosphors. The YAG:Cr phosphor screen has spectral output primarily in the red, the ZnGa/sub 2/O/sub 4/, in the blue. Outgassing products were measured outside the line-of-sight of both the FEA and phosphor screens. Therefore, if the FEA-screen pairs studied were in a flat panel display, the products detected would be those pumped by appendage pumps mounted on the flat panel. In the current study, we do not measure the source of the products (FEA or screen).
Previous synthetic array methods for intraluminal imaging of coronary arteries have been greatly extended. First, a 64 element, high efficiency, ceramic piezoelectric, array transducer operating at 20 MHz has been con...
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Previous synthetic array methods for intraluminal imaging of coronary arteries have been greatly extended. First, a 64 element, high efficiency, ceramic piezoelectric, array transducer operating at 20 MHz has been constructed. The array is mounted on the surface of a 1.2 mm diameter catheter appropriate for coronary artery applications. Second, integrated into the catheter tip is a custom analog chip set permitting complete data capture from the array. That is, on each firing any combination of array elements can be selected independently as transmitter or receiver. Using data acquired in this way, a complete phased array aperture (i.e. independent transmit and receive apertures) can be reconstructed. To create real-time images, a beam former based on a custom application specific integrated circuit (ASIC) has been designed and built. Beam forming coefficients were derived using an optimal filtering approach accounting for the circular geometry of the array.
作者:
Tonjes, David J.Heil, James H.Black, John A.David J. Tonjes is a doctoral candidate in coastal oceanography at the Marine Sciences Research Center
University at Stony Brook through its Waste Management Institute (Waste Management Institute Marine Sciences Research Center University at Stony Brook 11794–5000). Under a grant from the Town Board he is a technical adviser to the commissioner of waste management of the town of Brookhaven New York in solid waste planning regulatory compliance and environmental site monitoring. Tonjes has a B.A. in liberal arts from St. John's College an M.S. in computer science from New York Institute of Technology and an M.S. in technological systems management from the University at Stony Brook. James H. Heil is commissioner of waste management for the town of Brookhaven (Department of Waste Management
Town of Brookhaven 3233 Rte. 112 Medford NY 11763). Heil received a B.S. from Manhattan College and an M.S. from New York University in civil engineering and is a licensed professional engineer in New York. He is a former president of the New York State Solid Waste Management Association. John A. Black is the coordinator of the environmental science program at Suffolk County Community College (Environmental Science Program
Suffolk County Community College Selden NY 11784). He is currently the chair of the Ecology Committee of the Pine Barrens Advisory Committee for Suffolk County and is a member of the Suffolk County Pine Barrens Review Commission. Black received a B.S. in chemistry from Adephi University an M.S. in public administration from the University at Stony Book an M. S. from Hofstra University and a Ph. D. from Adlephi in marine sciences.
Stiff diagrams arc a multivariate method of analysis used to describe the chemical state of ground water. The use of Stiff diagrams to describe multiconstituent contamination sites, such as landfills, has distinct adv...
This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (DECmpp 12000), the technique of distributed computing in the UNIX environment, and the comb...
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This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (DECmpp 12000), the technique of distributed computing in the UNIX environment, and the combination of TLM analysis with Prony's method as well as with autoregressive moving average (ARMA) digital signal processing for electromagnetic field modelling. By combining these advanced computation techniques, typical electromagnetic field modelling of microwave structures by TLM analysis can be accelerated by a few orders of magnitude.
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