Donna M. Mooney

Spectral analysis of heart rate variability during quiet sleep in normal human fetuses between 36 and 40 weeks of gestation.

Respiratory sinus arrhythmia (RSA) is a clinical manifestation of the parasympathetic nervous system which can be identified in the high-frequency region of the heart rate variability (HRV) power spectrum. The purpose of this study was to determine the relative contribution of RSA to overall HRV for human fetuses in quiet sleep. The study population consisted of 13 normal human fetuses between 36 and 40 weeks of gestation for whom data were collected during spontaneous breathing and normally occurring apneic periods. Fetal breathing was monitored continuously using real-time sonography. The fetal electrocardiogram was captured transabdominally in 3-min blocks at a rate of 833 Hz and fetal R-waves were extracted from the raw signal using adaptive signal processing techniques. Fetal behavioral state was determined at the beginning and end of each 3-min data collection period. The fetal R-wave interbeat intervals (IBIs) were converted to equally-spaced, time-based data, and linear detrending of the time series was accomplished by subtracting the mean heart period from each weighted IBI. Total power (TP, 0.0-2.5 Hz) was divided into RSA (0.4-1.0 Hz), high-frequency (HF, 0.2-2.5 Hz), low-frequency (LF, 0.04-0.2 Hz), and very-low-frequency (VLF, 0.0-0.04 Hz) regions, and the power densities were summed to determine the absolute power for each frequency component. A total of 81 3-min blocks (mean per subject 6.3, range 2-14) were available for analysis. Eleven (85%) of 13 fetuses demonstrated a HF peak during fetal breathing, and RSA accounted for approximately 20% of the TP.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral state affects heart rate response to low-intensity sound in human fetuses

The cardiac orienting reflex is elicited by a low-intensity sound, it consists of a sustained heart rate (HR) deceleration, and it is a specific physiological correlate of cognitive processing. In this study we examined the relationship between behavioral state and the cardiac orienting reflex in 75 human fetuses between 36 and 40 weeks gestation. Each fetus was stimulated with a 30-s speech sound at an average intensity of 83 dB SPL in quiet sleep (QS) and active sleep (AS). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal processing. Fetal behavioral states were assigned based on HR pattern and the presence or absence of eye and general body movements. We found that a significant HR deceleration occurred, in both QS and AS, following stimulus onset. However, HR decelerations occurred more often in QS than AS; and for fetuses exhibiting a HR deceleration, the magnitude of the deceleration was greater in AS compared to QS. In addition, in AS female fetuses exhibited a larger, more sustained HR deceleratory response than male fetuses, but the seconds x gender interaction in QS was not significant. Based on these results, we concluded that behavioral state is an important determinant of the HR deceleratory response in human fetuses.

Behavioural state change in normal human fetuses following a single vibroacoustic stimulus: effect of duration of quiet sleep prior to stimulation

We examined 96 normal human fetuses between 37 and 41 weeks of gestation to determine the relationship between the duration of the active state following a single vibroacoustic stimulus (VAS) and the time spent in prestimulus state 1F, i.e. quiet sleep (QS). All fetuses were observed to enter state 1F prior to testing. After remaining in this state for 3 min, each fetus was randomized into one of three groups: no stimulation (Group I, N = 32); a single 1-s VAS delivered after 3-5 min of QS (Group II, N = 33); and a single 1-s VAS delivered after 18-20 min of QS (Group III, N = 31). Fetuses in Groups I, II, and III were otherwise behaviourally indistinguishable. Heart rate and eye and body movements were monitored until the fetus either returned to state 1F and remained in that state for 3 min or did not return to state 1F within 60 min. Of the 64 fetuses who were stimulated, 62 responded, indicating that there was no effect of prestimulus state duration on the sensitivity to VAS. Fetuses stimulated after 18-20 min of QS behaved similarly to fetuses who entered an active period spontaneously.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Basal Autonomic Status in Normal Human Term Fetuses by Heart Rate Variability Spectral Analysis: Preliminary Report

Measures of autonomic nervous system functioning have received considerable attention because of the recognition that differences in sympathetic-parasympathetic balance may account for differences in neurobehavioral development. The purpose of this study was to determine if human fetuses could be categorized as either sympathetic-dominated or parasympathetic-dominated based on an analysis of the resting heart rate variability power distribution. The study population consisted of 17 normal human fetuses in quiet sleep between 36 and 40 weeks gestation. The fetal electrocardiogram was captured transabdominally in 3-min blocks at a rate of 833 Hz and fetal R-waves were extracted from the raw data using adaptive signal processing techniques. The fetal R-wave interbeat intervals (IBls) were converted to equally spaced, time-based data, and linear detrending was accomplished by subtracting the mean heart period from each weighted IBI. Total power (TP, 0.0-2.5 Hz) was divided into respiratory sinus arrhythmia (R...

A PC-controlled data acquisition system for transabdominal recording of cardiac activity in the human fetus

Transabdominal f~ el~ “ography is noninvasive and allows for relatively precise evaluation of fetal cardiac activity as comparedto methods based on the processing of Doppler signals generated by cardiac valve motion. We described a portable, _ ~puter (P@Xmtldled data acquisition system designed to noninvasively capture R-waves in the fetal elednxardiogram. Electrical pOtelltidS generated by fetal cardiac activity were captured using standard cardiac electrodes positioned across the mati abdomen. Data were collected over eight channels at a rate of approximately 800 samples per second. The signals were pmceswd with an analog-to-digital converter using a unique doublequeuing and Random Access Menmy sotlware routine. Fetal R-waves could be rapidly extracted tlorn the stored data via an interactive graphical user interfke. In order to investigate the applicability of this system in a clinical setting, we examined three normal human fetuses at approximately 36 weeks of gestation. Single-channel fd R-waves Llomeach subject were averaged with the overall mean single-channel loss of data being 40’?/0(range of data 10ss per single channel: 13.8-98.3%). However, when the cleanest of the single-channel records was selected for each subject, the average fetal R-wave loss was reduced to approximately 15Y0. A fhrther reduction in fetal signal loss to < 5% was achieved by displaying all channels simuhneously, and this signal 10SSwas due almost exclusively to coupling of the fetal and maternal signals. We concluded that transabdomind fetal R-wave detection was possible with very little sigmd loss using a PCudrolled data acquisition system with multichannel visualization. Win&ion tocapywit&Mt ree8fforpwl ofthkm

An evaluation of type-10 homograph discrimination at the semi-colon level in Roget's International Thesaurus

crbl MgnotaJ Wwhlolt tbsttbe cqliaam mtmdeordimibuti for direct ~lsdWt8grbth6AcMcO#ghtMtiOr Jmd tbetitteoftba pubfkmiooa~i btitetppmr,andmim k#veatbat~kby ~oftbeAnOOMOnfor~~ MaebkaY.Tocqy otbetw@ orto-N!quile4 afce Bnd/orspcci6c permkck A~-SAC W2t93AU USA ~ 1993ACM 0JJ9791-36b~S130 INTRODUCTION Although high resolution imaging techniques have greatly facilitatedthe earlyidentificationof stmctud anomaliesin the humanfetus,it is notpssible at the presenttimeto evaluatethe neurologicalstatus of even the grossly abnormalfetus. Sioce abnormalstructureis not at all synonymouswith abnd tkti~ the burdenis placed on the prinatdogist to predict neurobehavioraloutcome using indirectmeasures,suchas by assessingthe fetal heat rate (FHR) pattern. However, simply examhing long term variability in the FHR has a rather low predictive valw, although there is a relationship between FHR and specitic central nervous system (CNS) lesions in anencephalic f[1], the relationship between FHR sod fXS activity is tltr Iiom complete, since an abnormal FHR pattern is not predictive of developmental outcome in StNctumlly normal infknts [2]. However, considerable success in predicting neurobebavioml outcome has been achieved in neonates and irthts by aamhing the coupling between cardiac activity and other physiological variables, such as respiration [3-6]. Changes in hcmt rate associated with breathing are mediated by the vagus nerve and provide a measure of autonomic nervous system activity [6]. Abnormal sympathetiqxarmympathetic balance in the neonatal period appears to be a predictor of abnormal &velopmental outcome later in life [4]. Therefore, in an effort to enhance the predictive value of FHR monitoring, we have developed a portable, peraomd computer (PC)-controlled data acquisition system for noninvaaively collecting R-waves in the human fti eldmcardiogram (ECG) while simultaneously observkg f~ mspimtion with real-time sonography. The fetal cardiac signal was uptured over eight channels with standard cardiac eledrodes attached to the maternal abdomen. Adaptive signal pmcwing techniques, which included an interactive graphical intake, were used to extract fetal R-waves tiom the raw signal. In this paper we have discussed the hardware and Aware design considerations 622 which were adhased in the process of developing this PC-W data acquisition system. Particular emphasis was placed on the clinical application of this instrumentation.

Homograph discrimination for intelligent interfaces via thesaural lexicons (abstract)

This paper reports the results of evaluating a large sample of the 23,858 type-10 homographs found in Rogets International Thesaurus (3rd Ed.) as defined by the Bryan Model of abstract thesauri, of which Rogets is an instantiation. According to the Bryan model, two different entries in a thesaurus that have the same spelling are homographs (semantically unrelated) if and only if they cannot be the endpoints of a sequence of entries called a type-10 chain. The Bryan definition of a type-10 homograph has not been tested thoroughly until recently because of the combinatorial complexity associated with a direct application of the definition to a large instantiation such as Rogets. However, in 1989, the authors were able to decompose Rogets in into its type-10 components, and as a result, generate all 23,858 type-10 homographs at the semi-colon category level. The principal result is that Bryans definition of homographs by type-10 semantic disjunction does not appear to work uniformly over a broad range of entries in Rogets when the selected semantic category is the semi-colon group. Although there are many cases where type-10 homographs agree with conventional classifications, in general type-10 discrimination at the semi-colon level “over discriminates” in that it generates many more homographs than are found in standard English language dictionaries.

Heart rate dynamics in low risk human fetuses.

Thesaural lexicons, in particular Rogets International Thesaurus, represent a rich knowledge-base of culturally validated semantic associations which extend over most of the English language. It has been shown that the Thesaurus can be a valuable tool in non-domain-specific approaches to natural language Artificial Intelligence. The importance of this approach is being able to go beyond the explicit semantic connections within categories of association into the implicit semantic connections between categories. The implementation of Robert Bryans mathematical model for abstract thesauri is directed toward this implicit structure. Bryans model defines a strong semantic connectedness between two entries by a structure called a Type-10 chain. Type-10 connectedness is also an equivalence relation which defines a partition of the thesaurus. These strongly connected components can be used as a tool for disambiguation of homographs (words which are spelled identically which may have different meanings) an important feature of any natural language interface. The implementation of the model involves decomposition by the recently developed Method of Quarters. This algorithm is used to reduce the combinatoric complexity of the model.. Using this method, the authors were able to compute all 139,638 Type-10 components and locate 23,858 Type-10 homographs at the semi-colon category level in Rogets International Thesaurus, 3rd Edition. The present focus of the research is to combine a feature-based parser which will decompose sentences into syntactic components and then resolve any semantic ambiguities by application of the implicit semantic structures in the lexicon of Type-10 homographs. This technique is now being developed for a Student Advising Expert System. This work can also be extended to use semantic structures not only as a lexicon for the disambiguation of homographs, but also for text generation and for abstract classification applications.

An expert system for check routing (abstract and references only)

Evaluation of nonlinear heart rate (HR) dynamics has received considerable attention in the pediatric literature because such analyses not only provide insight into underlying control mechanisms, but may also help to differentiate between normal and abnormal infants. The purpose of this study was to determine, in eight low risk human fetuses, if nonlinear HR dynamics could be identified by analyzing the dispersion of interbeat intervals at slow (Ds) and fast (Df) HRs. The fetal cardiac electrical signal was captured transabdominally at a resolution of ±1 ms. To test the null hypothesis, that the time series is the result of a linear stochastic process, Ds and Df for the original time series were compared with the values calculated for three linear models. The linear models were constructed to preserve the major statistical properties of the original time series, including the mean, SD, and the Fourier power spectrum. For each fetus, there was no evidence of nonlinear cardiac dynamics based on analyses of Ds and Df. In contrast, the distribution of adjacent R-R intervals and the pattern of change across three successive interbeat intervals both revealed significant nonlinearities in HR control in each fetus. If the difference between normal and abnormal infants is the result of aberrant control of nonlinear processes, then our findings indicate that parameters which describe the nonlinearity may be more useful then Ds and Df in assigning a risk status.

Human fetuses have nonlinear cardiac dynamics

One of the most important tasks that a financial institution deals with on a daily basis is that of check processing. The goal of this project is to develop an automated systems that can perform an analysis of past item processing patterns and offer alternative routing and bundling procedures that will decrease costs and increase fund availability [4]. The system is intended to design cost-efficient sort patterns for those institutions that do not have a float manager and to offer an advanced decision support tool for managers at larger institutions.