A rounding lemma is presented which has applications in the field of discrete mathematics. The lemma can be used to simplify complex terms and analyse certain recurrence relations.
A rounding lemma is presented which has applications in the field of discrete mathematics. The lemma can be used to simplify complex terms and analyse certain recurrence relations.
Measurement of aortic input impedance in the rat is complicated by a high basal heart rate but is possible if appropriate compensation is made for frequency-dependent errors in modulus and phase resulting from analog ...
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Measurement of aortic input impedance in the rat is complicated by a high basal heart rate but is possible if appropriate compensation is made for frequency-dependent errors in modulus and phase resulting from analog filters in the equipment and from nonalignment of pressure and flow sensors. Because input impedance is a complex quantity, accurate values for both phase and modulus are required before meaningful interpretation of the data can be made. We measured aortic pressure and electromagnetic ascending aortic blood flow in mature, ether-anesthetized, open-chest male Wistar rats. Pressure and flow waveforms were averaged in the time domain and converted to Fourier series. Flow moduli were corrected for the measured frequency response of the flowmeter. Phase spectra were corrected by the classic frequency-domain and two new time-domain methods. Compensation for instrumentation errors was assessed at two different flowmeter filter settings in five animals. Reproducibility, variability, and the effects of vasoconstriction were assessed in 43 animals. Three methods of estimating characteristic impedance from the impedance spectra were evaluated and found to produce comparable results at baseline and following pharmacological elevation of blood pressure with graded methexamine infusion. Physiologically equivalent values for phase, as assessed by comparing oscillatory power calculated from the impedance spectra, were obtained with each of the phase-correction techniques. The new time-domain methods facilitate the assessment of aortic input impedance in this small animal model because they do not require measurement of the spatial separation between pressure and flow transducers and pulse wave velocity in the proximal aorta.
A technique is presented for three-dimensional (3-D) reconstruction of the left-ventricular endocardial surface from multiplanar transesophageal echocardiograms, using both commercial software and investigator written...
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A technique is presented for three-dimensional (3-D) reconstruction of the left-ventricular endocardial surface from multiplanar transesophageal echocardiograms, using both commercial software and investigator written Fortran programs for Intel 80286 and 80386 microcomputers. The approach provides quantitative global and regional cardiac performance measures and allows viewing the endocardial surface, at end-diastole and end-systole, from chosen perspectives. Anatomical landmarks are incorporated to aid in orientation. For regional calculation, the surface is divided into equal angular elements with each conceptually connected to the left-ventricular end-diastole centroid, forming a pyramidal volume element. This angular division automatically normalizes for heart size. The fractional change of these elements over the cardiac cycle provides a regional ejection fraction measure which is color-coded on the reconstructed endocardial surface. Composite perspective views, regional ejection fraction histograms and calculations of global end-diastolic, end-systolic, and stroke volumes, are all performed by the method.
In this paper, computer algorithms are developed for determining optimal purchasing strategies for firms that receive extended payment terms from vendors. The resultant models are particularly attractive in high-volum...
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In this paper, computer algorithms are developed for determining optimal purchasing strategies for firms that receive extended payment terms from vendors. The resultant models are particularly attractive in high-volume environments with extended payment terms, a high opportunity cost of capital, and relatively large inventory-related costs. It is shown that purchases of quantities smaller than the traditional Economic Order Quantity may be appropriate in these environments and other situations where vendors offer either all-units or incremental purchase price discounts. The resultant algorithms are solved in this study using a spreadsheet-based search procedure implemented on a personal computer.
A comprehensive analysis of reported hepatitis C virus genomic sequences comprising 151 partial or complete nucleotide sequences and 159 partial or complete amino acid sequences revealed an irregular composition of co...
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A comprehensive analysis of reported hepatitis C virus genomic sequences comprising 151 partial or complete nucleotide sequences and 159 partial or complete amino acid sequences revealed an irregular composition of conserved and variable regions. There were but eight conserved nucleotide sequences, none outside the 5' noncoding and structural regions. A search among conserved amino acid sequences revealed 14 candidate B-cell epitopes, which were chosen mainly on the basis of their hydrophilicity profiles. Twenty five candidate T-cell epitopes were selected according to the criteria of absolute conservation of amino acid sequence, together with characteristic sequence motifs, amphipathic helical structure, or both. Conserved peptide sequences, with the characteristics of both B- and T-cell epitopes, were identified in the nonstructural 5 (NS5) region of the genome.
An important, yet seemingly unattainable, goal in structural molecular biology is to be able to predict the native three-dimensional structure of a protein entirely from its amino acid sequence. Prediction methods bas...
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An important, yet seemingly unattainable, goal in structural molecular biology is to be able to predict the native three-dimensional structure of a protein entirely from its amino acid sequence. Prediction methods based on rigorous energy calculations have not yet been successful, and best results have been obtained from homology modelling and statistical secondary structure prediction. Homology modelling is limited to cases where significant sequence similarity is shared between a protein of known structure and the unknown. Secondary structure prediction methods are not only unreliable, but also do not offer any obvious route to the full tertiary structure. Recently, methods have been developed whereby entire protein folds are recognized from sequence, even where little or no sequence similarity is shared between the proteins under consideration. In this paper we review the current methods, including our own, and in particular offer a historical background to their development. In addition, we also discuss the future of these methods and outline the developments under investigation in our laboratory.
A mechanical system, such as a robot system for man-robot cooperation, a master-slave manipulator system, a power-steering system, an extender etc. has interactions among the system, the operator and its environment. ...
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ISBN:
(纸本)0780307534
A mechanical system, such as a robot system for man-robot cooperation, a master-slave manipulator system, a power-steering system, an extender etc. has interactions among the system, the operator and its environment. How to control the interactions so that the desired interaction is realized, is one of the key issues for the control of such a mechanical system. The design of the controller of mechanical systems with man-machine interactions is discussed. The authors first model the mechanical system, which has interactions with its environment and an operator, then propose a control algorithm so that the desired interaction is realized. The proposed control system, consists of two controllers: one generates the desired motion of the mechanical system based on the force applied to the system, and the other one controls the interaction between the system and its environment. The proposed control algorithm specifies both force augmentation and maneuverability of the system. The algorithm is applied to a planar manipulator with one degree of freedom and the experimental system illustrates the concept of the system.
We investigate numerically totalistic cellular automata rules in four and five dimensions that have been recently proposed by Chaté and Manneville and that show periodic or quasiperiodic time sequences in the mag...
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We investigate numerically totalistic cellular automata rules in four and five dimensions that have been recently proposed by Chaté and Manneville and that show periodic or quasiperiodic time sequences in the magnetization. We show how to implement such rules fast on a Connection Machine. We confirm the proposed behavior by analyzing the time and size dependence of the distance from the attractor. Also the dependence of the initial configuration, the behavior of very small systems and mean-field calculations are presented.
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