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Engineering analysis of biological variables: An example of blood pressure over 1 day

Huang, Wei and Shen, Zheng and Huang, Norden E. and Fung, Yuan Cheng (1998) Engineering analysis of biological variables: An example of blood pressure over 1 day. Proceedings of the National Academy of Sciences of the United States of America, 95 (9). pp. 4816-4821. ISSN 0027-8424. PMCID PMC20170. doi:10.1073/pnas.95.9.4816.

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Almost all variables in biology are nonstationarily stochastic. For these variables, the conventional tools leave us a feeling that some valuable information is thrown away and that a complex phenomenon is presented imprecisely. Here, we apply recent advances initially made in the study of ocean waves to study the blood pressure waves in the lung. We note first that, in a long wave train, the handling of the local mean is of predominant importance. It is shown that a signal can be described by a sum of a series of intrinsic mode functions, each of which has zero local mean at all times. The process of deriving this series is called the “empirical mode decomposition method.” Conventionally, Fourier analysis represents the data by sine and cosine functions, but no instantaneous frequency can be defined. In the new way, the data are represented by intrinsic mode functions, to which Hilbert transform can be used. Titchmarsh [Titchmarsh, E. C. (1948) Introduction to the Theory of Fourier Integrals (Oxford Univ. Press, Oxford)] has shown that a signal and i times its Hilbert transform together define a complex variable. From that complex variable, the instantaneous frequency, instantaneous amplitude, Hilbert spectrum, and marginal Hilbert spectrum have been defined. In addition, the Gumbel extreme-value statistics are applied. We present all of these features of the blood pressure records here for the reader to see how they look. In the future, we have to learn how these features change with disease or interventions.

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Additional Information:© 1998 National Academy of Sciences. Contributed by Yuan Cheng Fung, February 20, 1998. This work was supported by National Institutes of Health-National Heart, Lung, and Blood Institute Grant HL 43026; American Heart Association, California Affiliate, Postdoctoral Fellowship 96-95 (W.H.); National Science Foundation CM-9615897 (Z.S.); and National Aeronautics and Space Administration RTOP 622-47-11-20 (N.E.H.). The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked ‘‘advertisement’’ in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Funding AgencyGrant Number
NIHHL 43026
American Heart Association96-95
NASARTOP 622-47-11-20
Subject Keywords:Fourier spectrum; Hilbert spectrum; Gumbel extreme-value statistics; pulmonary artery
Issue or Number:9
PubMed Central ID:PMC20170
Record Number:CaltechAUTHORS:20141126-101042358
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Official Citation:Huang, W., Shen, Z., Huang, N. E., & Fung, Y. C. (1998). Engineering analysis of biological variables: An example of blood pressure over 1 day. Proceedings of the National Academy of Sciences, 95(9), 4816-4821.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52178
Deposited On:26 Nov 2014 18:59
Last Modified:10 Nov 2021 19:22

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