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A. J. Rawson

Bio: A. J. Rawson is an academic researcher. The author has contributed to research in topics: Cardiac function curve & BALLISTOCARDIOGRAPH. The author has an hindex of 2, co-authored 2 publications receiving 377 citations.


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Journal ArticleDOI
TL;DR: Evidence bearing on the intrinsic control of the human cerebral circulation as revealed by quantitative measurements is derived.
Abstract: A method for measuring quantitatively the volume of cerebral blood flow in man by inhalation of nitrous oxide (1) found its first application in a study of the cerebral circulatory effects of low CO2 tension achieved by hyperventilation; of high CO2 tension, and of high and low 02 tensions obtained by inhalation of appropriate gas mixtures (2). Only the first part of this study, the effects of active and passive hyperventilation, has been published in detail (3). The purpose of the present paper is to present the remainder of these findings and to derive from them, together with those of the hyperventilation experiments, evidence bearing on the intrinsic control of the human cerebral circulation as revealed by quantitative measurements.

1,768 citations

Journal ArticleDOI
TL;DR: This review explains the conventional BP measurement methods and their limitations; presents models to summarize the theory of the PTT-BP relationship; outlines the approach while pinpointing the key challenges; and discusses realistic expectations for the approach.
Abstract: Ubiquitous blood pressure (BP) monitoring is needed to improve hypertension detection and control and is becoming feasible due to recent technological advances such as in wearable sensing. Pulse transit time (PTT) represents a well-known potential approach for ubiquitous BP monitoring. The goal of this review is to facilitate the achievement of reliable ubiquitous BP monitoring via PTT. We explain the conventional BP measurement methods and their limitations; present models to summarize the theory of the PTT-BP relationship; outline the approach while pinpointing the key challenges; overview the previous work toward putting the theory to practice; make suggestions for best practice and future research; and discuss realistic expectations for the approach.

648 citations

Proceedings ArticleDOI
23 Jun 2013
TL;DR: This method tracks features on the head and performs principal component analysis (PCA) to decompose their trajectories into a set of component motions and chooses the component that best corresponds to heartbeats based on its temporal frequency spectrum.
Abstract: We extract heart rate and beat lengths from videos by measuring subtle head motion caused by the Newtonian reaction to the influx of blood at each beat. Our method tracks features on the head and performs principal component analysis (PCA) to decompose their trajectories into a set of component motions. It then chooses the component that best corresponds to heartbeats based on its temporal frequency spectrum. Finally, we analyze the motion projected to this component and identify peaks of the trajectories, which correspond to heartbeats. When evaluated on 18 subjects, our approach reported heart rates nearly identical to an electrocardiogram device. Additionally we were able to capture clinically relevant information about heart rate variability.

580 citations

Journal ArticleDOI
01 Jul 2015
TL;DR: The recent advances in modern BCG and SCG research are reviewed, including reduced measurement noise, clinically relevant feature extraction, and signal modeling.
Abstract: In the past decade, there has been a resurgence in the field of unobtrusive cardiomechanical assessment, through advancing methods for measuring and interpreting ballistocardiogram (BCG) and seismocardiogram (SCG) signals. Novel instrumentation solutions have enabled BCG and SCG measurement outside of clinical settings, in the home, in the field, and even in microgravity. Customized signal processing algorithms have led to reduced measurement noise, clinically relevant feature extraction, and signal modeling. Finally, human subjects physiology studies have been conducted using these novel instruments and signal processing tools with promising results. This paper reviews the recent advances in these areas of modern BCG and SCG research.

558 citations