176 research outputs found
Predicting Bradycardia in Preterm Infants Using Point Process Analysis of Heart Rate
No full textObjective: Episodes of bradycardia are common and recur sporadically in preterm infants, posing a threat to the developing brain and other vital organs. We hypothesize that bradycardias are a result of transient temporal destabilization of the cardiac autonomic control system and that fluctuations in the heart rate signal might contain information that precedes bradycardia. We investigate infant heart rate fluctuations with a novel application of point process theory. Methods: In ten preterm infants, we estimate instantaneous linear measures of the heart rate signal, use these measures to extract statistical features of bradycardia, and propose a simplistic framework for prediction of bradycardia. Results: We present the performance of a prediction algorithm using instantaneous linear measures (mean area under the curve = 0.79 ± 0.018) for over 440 bradycardia events. The algorithm achieves an average forecast time of 116 s prior to bradycardia onset (FPR = 0.15). Our analysis reveals that increased variance in the heart rate signal is a precursor of severe bradycardia. This increase in variance is associated with an increase in power from low content dynamics in the LF band (0.04-0.2 Hz) and lower multiscale entropy values prior to bradycardia. Conclusion: Point process analysis of the heartbeat time series reveals instantaneous measures that can be used to predict infant bradycardia prior to onset. Significance: Our findings are relevant to risk stratification, predictive monitoring, and implementation of preventative strategies for reducing morbidity and mortality associated with bradycardia in neonatal intensive care units
Uncovering statistical features of bradycardia severity in premature infants using a point process model
No full textImproving heart rate estimation in preterm infants with bivariate point process analysis of heart rate and respiration
No full textAccurate estimation of heart rate dynamics in preterm infants is important for predicting recurrent episodes of severe bradycardia. We hypothesize that estimation of heart rate can be improved by including respiration as a state variable, based on mechanisms that underlie cardio-respiratory coherence. For ten preterm infants, we demonstrate that including respiration as a covariate improves estimation accuracy by an average of 11% across bradycardia severity, and reduces the maximum error by 8%. We also find that cardio-respiratory coherence increases in low frequency content just prior to severe bradycardia. Thus, incorporating respiratory information may improve models of heart rate dynamics and narrow potential features for bradycardia prediction
Point process time-frequency analysis of dynamic respiratory patterns during meditation practice
No full textRespiratory sinus arrhythmia (RSA) is largely mediated by the autonomic nervous system through its modulating influence on the heart beats. We propose a robust algorithm for quantifying instantaneous RSA as applied to heart beat intervals and respiratory recordings under dynamic breathing patterns. The blood volume pressure-derived heart beat series (pulse intervals, PIs) are modeled as an inverse Gaussian point process, with the instantaneous mean PI modeled as a bivariate regression incorporating both past PIs and respiration values observed at the beats. A point process maximum likelihood algorithm is used to estimate the model parameters, and instantaneous RSA is estimated via a frequency domain transfer function evaluated at instantaneous respiratory frequency where high coherence between respiration and PIs is observed. The model is statistically validated using Kolmogorov–Smirnov goodness-of-fit analysis, as well as independence tests. The algorithm is applied to subjects engaged in meditative practice, with distinctive dynamics in the respiration patterns elicited as a result. The presented analysis confirms the ability of the algorithm to track important changes in cardiorespiratory interactions elicited during meditation, otherwise not evidenced in control resting states, reporting statistically significant increase in RSA gain as measured by our paradigm
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An Ultra-Wide Band Radar Based Noncontact Device for Real-time Apnea Detection
No full textThis thesis presents a real-time noncontact system that can monitor an infant's respiration and detect apnea when it occurs. For infants, bedside monitoring of respiratory signals using non-contact sensors is desirable at the hospital and for in-home care. Traditional approach employs acoustic sensors which can hardly detect infant breathing due to low SNR. In this thesis, a novel method is introduced by using a ultra-wideband (UWB) radar that obtains breathing signal from an infant's weak chest vibration. Furthermore, advanced signal processing techniques are proposed to monitor the breathing signal and to detect apnea. Since an infant may move in the crib, a location algorithm is applied periodically to track the current location of the infant's chest. An apnea warning is issued when the respiration is absent for a pre-defined period of time
Assessment of cardio-respiratory interactions in preterm infants by bivariate autoregressive modeling and surrogate data analysis
No full textBackground: Cardio-respiratory interactions are weak at the earliest stages of human development, suggesting that assessment of their presence and integrity may be an important indicator of development in infants. Despite the valuable research devoted to infant development, there is still a need for specifically targeted standards and methods to assess cardiopulmonary functions in the early stages of life. We present a new methodological framework for the analysis of cardiovascular variables in preterm infants. Our approach is based on a set of mathematical tools that have been successful in quantifying important cardiovascular control mechanisms in adult humans, here specifically adapted to reflect the physiology of the developing cardiovascular system.
Methods: We applied our methodology in a study of cardio-respiratory responses for 11 preterm infants. We quantified cardio-respiratory interactions using specifically tailored multivariate autoregressive analysis and calculated the coherence as well as gain using causal approaches. The significance of the interactions in each subject was determined by surrogate data analysis. The method was tested in control conditions as well as in two different experimental conditions; with and without use of mild mechanosensory intervention.
Results: Our multivariate analysis revealed a significantly higher coherence, as confirmed by surrogate data analysis, in the frequency range associated with eupneic breathing compared to the other ranges.
Conclusions: Our analysis validates the models behind our new approaches, and our results confirm the presence of cardio-respiratory coupling in early stages of development, particularly during periods of mild mechanosensory intervention, thus encouraging further application of our approach.Center for Integration of Medicine and Innovative Technology (U.S. Army Medical Research Acquisition Activity Cooperative Agreement W81XWH-07-2-0011)National Institutes of Health (U.S.) (Grant R01-HL084502)National Institutes of Health (U.S.) (Grant R01-DA015644)National Institutes of Health (U.S.) (Grant DP1-OD003646
History of Indic Scripts
No full textThe present study offers an introductory survey on the history of Indic scripts. It was prepared in the frame of the E-QUAL project, and it provided the narrative structure on which a Moodle module on the same topic was built by the present author. Basically, it focuses on the developments of the Indic scripts, from the time of their earliest available attestations up to the time when the major present-day (modern) scripts reached their current form.
The study is organized in six chapters. The first chapter has a prefatory character, in that it offers a general contextualization of what will be covered in the following sections of the work: the general plan of the work is outlined, the basic concepts are defined, and the major phenomena connected with the history of the Indic scripts are presented. In chapters two through six, a chronological account of the development of the Indic scripts is given, from their earliest attestations up to their current form. Chapter six is followed by three additional sections (Appendices), each focusing on a specific topic, i.e. the languages used in Indian inscriptions, the Siddhamātṛkā script, and the typological classification of the Indic scripts
T. S. Eliot and Indic Traditions
No full textT. S. Eliot's allusions to Indic philosophy in several poems - from the Sanskrit ending of The Waste Land to the 'What Krishna meant' section of Four Quartets - have puzzled and intrigued readers since the poems first appeared. In T. S. Eliot and Indic Traditions, Professor Cleo McNelly Kearns places Eliot's lifelong interest in Indic philosophy and religion in the context of his concomitant studies in Western philosophy and his views on literary theory and poetic practice. The author establishes the depth and extent of his knowledge not only of Sanskrit and Pali texts but also of the scholarly tradition through which they were interpreted in the West. She explores as well Eliot's keen sense of the important distinctions between specific schools of thought. Kearns concludes that Eliot was less interested in synthesizing various traditions than in comparing texts and traditions for what he called 'the difference they can make to one another'.</jats:p
Indic Lexicon in the English/Creole of Trinidad
No full textExamines the contemporary lexical component of the English/Creole of Trinidad (TEC) that is derived from languages of India. Author focuses on the TEC as spoken among Indo-Trinidadians, but also pays attention to Indic words used in the TEC of Afro-Trinidadians and other groups. Author sketches the history of Indian immigration into Trinidad, explaining how most came from the Bihar province in northern India and spoke Bhojpuri, rather than (closely related) Hindi, and how in the 20th c. Indian languages were replaced by English with education. She further focuses on retained Indic words incorporated in current-day TEC, and found 1844 of such words in usage. She discusses words misassigned locally as Indian-derived, but actually from other (European or African) languages. Then, she describes most of the Indo-TEC lexicon, categorizing items by their semantic-cultural domain, with major domains for Indian-derived words: religious practice, music, dance and stickfighting, food preparation, agriculture, kinship, and behaviour or appearance. Further, the author discusses to what degree Indic words have been mainstreamed within the non-Indian population of Trinidad, sometimes via standard English, sometimes directly assimilated into TEC, and made salient through the press or street food selling
Indic Lexicon in the English/Creole of Trinidad
No full textExamines the contemporary lexical component of the English/Creole of Trinidad (TEC) that is derived from languages of India. Author focuses on the TEC as spoken among Indo-Trinidadians, but also pays attention to Indic words used in the TEC of Afro-Trinidadians and other groups. Author sketches the history of Indian immigration into Trinidad, explaining how most came from the Bihar province in northern India and spoke Bhojpuri, rather than (closely related) Hindi, and how in the 20th c. Indian languages were replaced by English with education. She further focuses on retained Indic words incorporated in current-day TEC, and found 1844 of such words in usage. She discusses words misassigned locally as Indian-derived, but actually from other (European or African) languages. Then, she describes most of the Indo-TEC lexicon, categorizing items by their semantic-cultural domain, with major domains for Indian-derived words: religious practice, music, dance and stickfighting, food preparation, agriculture, kinship, and behaviour or appearance. Further, the author discusses to what degree Indic words have been mainstreamed within the non-Indian population of Trinidad, sometimes via standard English, sometimes directly assimilated into TEC, and made salient through the press or street food selling
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