Journal articles: 'Beat'

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Mungali, Kalpna, and Hema Joshi. "Phytosociological Analysis of Forest Vegetation of Binsar Wildlife Sanctuary, Uttarakhand." Indian Journal of Forestry 36, no. 4 (December 1, 2013): 487–502. http://dx.doi.org/10.54207/bsmps1000-2013-u18db3.

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Present study was carried out in Binsar Wildlife Sanctuary, Uttarakhand during the period 2006-2007 Phytosociologcal study of the vegetation was conducted on the basis of floristic and structural variations. The diversity of trees, shrubs and herbs varied with Beats and Compartments. For example in South Binsar Block maximum tree diversity was recorded in Binsar Beat and minimum in Patanainail Beat. In North Binsar maximum diversity was recorded in Dhaulchina Beat and minimum in Satri Beat. In Rithagar Block the diversity was Zero. The maximum value of concentration of dominance for tree layer was observed in Patnainail Beat and minimum in Badaur Beat (in South Binsar). This value also varied with Beats and Compartments of Sanctuary.

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Repp, Bruno H., John R. Iversen, and Aniruddh D. Patel. "Tracking an Imposed Beat within a Metrical Grid." Music Perception 26, no. 1 (September 1, 2008): 1–18. http://dx.doi.org/10.1525/mp.2008.26.1.1.

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RHYTHMIC STRUCTURE OFTEN FAVORS a particular beat that is marked by frequent tone onsets and grouping accents. Using rhythms similar to those of Povel and Essens (1985), we asked musically trained participants to tap on physically or mentally imposed beats that either coincided with the favored beat or were phase-shifted relative to it. Surprisingly, tapping was equally stable. Actually, variability tended to be lowest when the imposed beat was in anti-phase with the favored beat; however, this tendency was reversed when participants were instructed to tap in anti-phase with the beat. These results demonstrate that precise on-beat synchronization with different imposed beats can be achieved by locking into the metrical grid defined by a rhythm's basic pulse. The favored beat provides the most stable reference for off-beat tapping but not necessarily for onbeat tapping, which relies to a greater extent on intervening rhythm tones as temporal references.

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Bunting, Karina V., Simrat K. Gill, Alice Sitch, Samir Mehta, Kieran O'Connor, Gregory YH Lip, Paulus Kirchhof, et al. "Improving the diagnosis of heart failure in patients with atrial fibrillation." Heart 107, no. 11 (March 10, 2021): 902–8. http://dx.doi.org/10.1136/heartjnl-2020-318557.

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ObjectiveTo improve the echocardiographic assessment of heart failure in patients with atrial fibrillation (AF) by comparing conventional averaging of consecutive beats with an index-beat approach, whereby measurements are taken after two cycles with similar R-R interval.MethodsTransthoracic echocardiography was performed using a standardised and blinded protocol in patients enrolled in the RATE-AF (RAte control Therapy Evaluation in permanent Atrial Fibrillation) randomised trial. We compared reproducibility of the index-beat and conventional consecutive-beat methods to calculate left ventricular ejection fraction (LVEF), global longitudinal strain (GLS) and E/e’ (mitral E wave max/average diastolic tissue Doppler velocity), and assessed intraoperator/interoperator variability, time efficiency and validity against natriuretic peptides.Results160 patients were included, 46% of whom were women, with a median age of 75 years (IQR 69–82) and a median heart rate of 100 beats per minute (IQR 86–112). The index-beat had the lowest within-beat coefficient of variation for LVEF (32%, vs 51% for 5 consecutive beats and 53% for 10 consecutive beats), GLS (26%, vs 43% and 42%) and E/e’ (25%, vs 41% and 41%). Intraoperator (n=50) and interoperator (n=18) reproducibility were both superior for index-beats and this method was quicker to perform (p<0.001): 35.4 s to measure E/e’ (95% CI 33.1 to 37.8) compared with 44.7 s for 5-beat (95% CI 41.8 to 47.5) and 98.1 s for 10-beat (95% CI 91.7 to 104.4) analyses. Using a single index-beat did not compromise the association of LVEF, GLS or E/e’ with natriuretic peptide levels.ConclusionsCompared with averaging of multiple beats in patients with AF, the index-beat approach improves reproducibility and saves time without a negative impact on validity, potentially improving the diagnosis and classification of heart failure in patients with AF.

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Cheung, Albert T., Joseph S. Savino, and Stuart J. Weiss. "Beat-to-beat Augmentation of Left Ventricular Function by Intraaortic Counterpulsation." Anesthesiology 84, no. 3 (March 1, 1996): 545–54. http://dx.doi.org/10.1097/00000542-199603000-00009.

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Background Measuring the effects of intraaortic balloon counterpulsation (IABP) in single cardiac beats may permit an improved understanding of the physiologic mechanisms by which IABP improves the circulation. The objective of the study was to use trans- esophageal echocardiography in combination with hemodynamic measurements to test the hypothesis that IABP improves global left ventricular systolic function selectively in the IABP-augmented cardiac beats by acutely decreasing left ventricular afterload. Methods Twenty-seven studies in which the IABP-to-R wave trigger ratio was serially changed from 1:1, 1:2, 1:4, 0:1 (IABP off) and back to 1:1 were performed in 20 anesthetized cardiac surgical patients during IABP support. Left ventricular short-axis end-diastolic cross-sectional area, end-systolic area, mean end-systolic wall thickness, and ejection time were measured by transesophageal echocardiography at the midpapillary muscle level. Aortic pressure was measured simultaneously from the central lumen of the intraaortic balloon catheter. These measurements were used to calculate the fractional area change, end-systolic meridional wall stress, and heart rate-corrected velocity of circumferential fiber shortening. The echocardiographic and hemodynamic parameters of left ventricular preload, afterload, and systolic function immediately after balloon deflation (IABP-augmented cardiac beats) were compared to the parameters measured during nonaugmented cardiac beats to determine the beat-to-beat effects of IABP on left ventricular function. Results IABP-augmented cardiac beats had a decreased systolic arterial pressure and end-systolic meridional wall stress and increased diastolic blood pressure, fractional area change, and velocity of circumferential fiber shortening compared to nonaugmented cardiac beats. IABP did not cause significant beat-to-beat changes in heart rate, pulmonary artery diastolic pressure, or central venous pressure. The improvement in left ventricular systolic function associated with IABP-augmented cardiac beats correlated with the decrease in end-systolic meridional wall stress for that cardiac beat. Conclusions Beat-to-beat echocardiographic and hemodynamic measurements performed in anesthetized cardiac surgical patients during IABP support demonstrated improved left ventricular systolic function and decreased left ventricular systolic wall stress in the cardiac beats immediately after balloon deflation. The relationship between left ventricular systolic function and left ventricular systolic wall stress during IABP support suggests that afterload reduction was an important mechanism by which IABP instantaneously improved circulatory function in anesthetized cardiac surgical patients.

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Yang, Lulu, Junjiang Zhu, Tianhong Yan, Zhaoyang Wang, and Shangshi Wu. "A Modified Convolutional Neural Network for ECG Beat Classification." Journal of Medical Imaging and Health Informatics 10, no. 3 (March 1, 2020): 654–60. http://dx.doi.org/10.1166/jmihi.2020.2913.

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Most convolutional neural networks (CNNs) used to classify electrocardiogram (ECG) beats tend to focus only on the beat, ignoring its relationships with its surrounding beats. This study aimed to propose a hybrid convolutional neural network (HCNN) structure, which classified ECG beats based on the beat's morphology and relationship such as RR intervals. The difference between the HCNN and the traditional CNN lies in the fact that the relationship can be added to any layer in the former. The HCNN was fed with RR intervals at 3 different positions, trained using data from 2170 patients. It was then evaluated with labeled clinical data from 2102 patients to classify ECG beats into premature ventricular contraction beat, atrial premature contraction beat (APC), left bundle branch block beat, right bundle branch block beat, and normal sinus beat. The results showed that the performance of the proposed HCNN method (with an average score of 86.61% on 12 leads) was 3.31% higher than that of the traditional CNN (83.30%) on the test set. In particular, the APC improved most significantly from 57.67% to 76.92% in terms of sensitivity and from 58.80% to 78.46% in terms of the positive predictive value in lead V1.

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Swenberg, Thorbjörn, and Simon Carlgren. "On-Beat/Off-Beat." Projections 15, no. 1 (March 1, 2021): 28–54. http://dx.doi.org/10.3167/proj.2021.150103.

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Audio-visual rhythm can be achieved in a variety of ways, in film as well as in music videos. Here, we have studied human visual responses to video editing with regard to musical beats, in order to better understand the role of visual rhythm in an audio-visual flow. While some suggest that music videos should maintain synchrony in the audio-visual rhythm, and others claim that music videos should be rhythmically loose in their structure, there is a functional aspect of vision and hearing that reacts to the juxtaposition of audio and visual rhythms. We present empirical evidence of cognitive effects, as well as perceptual differences with attentional effects, for viewers watching music videos cut on-beat and off-beat.

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HUANG, YEN-CHIEH. "LASER BEAT-WAVE BUNCHED BEAM FOR COMPACT SUPERRADIANCE SOURCES." International Journal of Modern Physics B 21, no. 03n04 (February 10, 2007): 287–99. http://dx.doi.org/10.1142/s0217979207042069.

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A periodically bunched electron beam is useful for generating high-brightness electron superradiance. This paper studies the generation and acceleration of density-modulated electron beams from a photocathode electron gun driven by a laser beat wave. Computer simulation shows the feasibility of accelerating and preserving the density-modulated electron beam in an accelerator. This paper also details the implementation of a beat-wave laser system with a variable beat frequency for driving a photocathode electron gun.

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Suzuki, Shunsuke, Junichi Araki, Terumasa Morita, Satoshi Mohri, Takeshi Mikane, Hiroki Yamaguchi, Shunji Sano, Tohru Ohe, Masahisa Hirakawa, and Hiroyuki Suga. "Ventricular contractility in atrial fibrillation is predictable by mechanical restitution and potentiation." American Journal of Physiology-Heart and Circulatory Physiology 275, no. 5 (November 1, 1998): H1513—H1519. http://dx.doi.org/10.1152/ajpheart.1998.275.5.h1513.

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We recently found that contractility ( E max) of an individual irregularly arrhythmic beat in electrically induced atrial fibrillation (AF) is reasonably predictable from the ratio of the preceding beat interval (RR1) to the beat interval immediately preceding RR1 (RR2) in the canine left ventricle. Moreover, the monotonically increasing relation between E max and the RR1-to-RR2 ratio (RR1/RR2) passed through or by the mean arrhythmic beat E max as well as the regular beat E max at RR1/RR2 = 1. We hypothesized that this E max-RR1/RR2 relation during irregular arrhythmia could be attributed to the basic characteristics of the mechanical restitution and potentiation. To test this, we adopted a known comprehensive equation describing the force restitution and potentiation as a function of two preceding beat intervals and simulated contractilities of irregular arrhythmic beats with randomized beat intervals on a computer. The simulated E max-RR1/RR2 relation reasonably resembled the one that we recently observed experimentally, supporting our hypothesis. We therefore conclude that the primary mechanism underlying the varying contractilities of irregular beats in AF is mechanical restitution and potentiation.

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Derner, Marlene, Leila Chaieb, Gert Dehnen, Thomas P. Reber, Valeri Borger, Rainer Surges, Bernhard P. Staresina, Florian Mormann, and Juergen Fell. "Auditory Beat Stimulation Modulates Memory-Related Single-Neuron Activity in the Human Medial Temporal Lobe." Brain Sciences 11, no. 3 (March 12, 2021): 364. http://dx.doi.org/10.3390/brainsci11030364.

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Auditory beats are amplitude-modulated signals (monaural beats) or signals that subjectively cause the perception of an amplitude modulation (binaural beats). We investigated the effects of monaural and binaural 5 Hz beat stimulation on neural activity and memory performance in neurosurgical patients performing an associative recognition task. Previously, we had reported that these beat stimulation conditions modulated memory performance in opposite directions. Here, we analyzed data from a patient subgroup, in which microwires were implanted in the amygdala, hippocampus, entorhinal cortex and parahippocampal cortex. We identified neurons responding with firing rate changes to binaural versus monaural 5 Hz beat stimulation. In these neurons, we correlated the differences in firing rates for binaural versus monaural beats to the memory-related differences for remembered versus forgotten items and associations. In the left hemisphere, we detected statistically significant negative correlations between firing rate differences for binaural versus monaural beats and remembered versus forgotten items/associations. Importantly, such negative correlations were also observed between beat stimulation-related firing rate differences in the pre-stimulus window and memory-related firing rate differences in the post-stimulus windows. In line with concepts of homeostatic plasticity, our findings suggest that beat stimulation is linked to memory performance via shifting baseline firing levels.

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Dawes, G. S. "Beat-to-beat variation." American Journal of Obstetrics and Gynecology 173, no. 1 (July 1995): 349. http://dx.doi.org/10.1016/0002-9378(95)90231-7.

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Dilaveris, Polychronis, Georgios Giannopoulos, Maria Riga, Andreas Synetos, and Christodoulos Stefanadis. "Beat by Beat Variations." American Journal of Medicine 120, no. 1 (January 2007): 21–22. http://dx.doi.org/10.1016/j.amjmed.2006.10.009.

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Williams, Ruth, and Andrea Shaw. "Beat (Beat Eating Disorders)." Nursing Management 22, no. 6 (September 30, 2015): 17. http://dx.doi.org/10.7748/nm.22.6.17.s21.

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Suh, Youngbo, and Thomas K. Ferris. "Examining Change Sensitivity to Vibrotactile Beats in a Hand-Held Touchscreen Device." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 61, no. 1 (September 2017): 1569. http://dx.doi.org/10.1177/1541931213601756.

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While recent research has employed vibrotactile feedback as a means of communication, one novel form of vibrotactile feedback involves the generation of “beats”. They are amplitude-modulated vibratory signals that can be created by sending multiple sinusoidal signals at dissonant frequencies (Lim, Kyung, & Kwon, 2012; Yang et al., 2014). The resulting perception of a rising-and-falling amplitude signal (a single “beat”), can be characterized per unit time as beat frequency, which is a function of the difference between the two input signal frequencies. Although vibrotactile beat cues have potentials in better supporting multitasking contexts that are visually demanding, the fundamental psychophysical characteristics of absolute and difference sensitivities have not been well-studied. To build on the promising but sparse findings involving the application of vibrotactile beats, it is important to define the limits of human perceptual ability to differentiate vibrotactile beats at distinct beat frequencies.

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Omer, Osama A., Mostafa Salah, Ammar M. Hassan, Mohamed Abdel-Nasser, Norihiro Sugita, and Yoshifumi Saijo. "Blood Pressure Estimation from Photoplythmography Using Hybrid Scattering–LSTM Networks." BioMedInformatics 4, no. 1 (January 9, 2024): 139–57. http://dx.doi.org/10.3390/biomedinformatics4010010.

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One of the most significant indicators of heart and cardiovascular health is blood pressure (BP). Blood pressure (BP) has gained great attention in the last decade. Uncontrolled high blood pressure increases the risk of serious health problems, including heart attack and stroke. Recently, machine/deep learning has been leveraged for learning a BP from photoplethysmography (PPG) signals. Hence, continuous BP monitoring can be introduced, based on simple wearable contact sensors or even remotely sensed from a proper camera away from the clinical setup. However, the available training dataset imposes many limitations besides the other difficulties related to the PPG time series as high-dimensional data. This work presents beat-by-beat continuous PPG-based BP monitoring while accounting for the aforementioned limitations. For a better exploration of beats’ features, we propose to use wavelet scattering transform as a better descriptive domain to cope with the limitation of the training dataset and to help the deep learning network accurately learn the relationship between the morphological shapes of PPG beats and the BP. A long short-term memory (LSTM) network is utilized to demonstrate the superiority of the wavelet scattering transform over other domains. The learning scenarios are carried out on a beat basis where the input corresponding PPG beat is used for predicting BP in two scenarios; (1) Beat-by-beat arterial blood pressure (ABP) estimation, and (2) Beat-by-beat estimation of the systolic and diastolic blood pressure values. Different transformations are used to extract the features of the PPG beats in different domains including time, discrete cosine transform (DCT), discrete wavelet transform (DWT), and wavelet scattering transform (WST) domains. The simulation results show that using the WST domain outperforms the other domains in the sense of root mean square error (RMSE) and mean absolute error (MAE) for both of the suggested two scenarios.

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Møller, Cecilie, Jan Stupacher, Alexandre Celma-Miralles, and Peter Vuust. "Beat perception in polyrhythms: Time is structured in binary units." PLOS ONE 16, no. 8 (August 20, 2021): e0252174. http://dx.doi.org/10.1371/journal.pone.0252174.

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In everyday life, we group and subdivide time to understand the sensory environment surrounding us. Organizing time in units, such as diurnal rhythms, phrases, and beat patterns, is fundamental to behavior, speech, and music. When listening to music, our perceptual system extracts and nests rhythmic regularities to create a hierarchical metrical structure that enables us to predict the timing of the next events. Foot tapping and head bobbing to musical rhythms are observable evidence of this process. In the special case of polyrhythms, at least two metrical structures compete to become the reference for these temporal regularities, rendering several possible beats with which we can synchronize our movements. While there is general agreement that tempo, pitch, and loudness influence beat perception in polyrhythms, we focused on the yet neglected influence of beat subdivisions, i.e., the least common denominator of a polyrhythm ratio. In three online experiments, 300 participants listened to a range of polyrhythms and tapped their index fingers in time with the perceived beat. The polyrhythms consisted of two simultaneously presented isochronous pulse trains with different ratios (2:3, 2:5, 3:4, 3:5, 4:5, 5:6) and different tempi. For ratios 2:3 and 3:4, we additionally manipulated the pitch of the pulse trains. Results showed a highly robust influence of subdivision grouping on beat perception. This was manifested as a propensity towards beats that are subdivided into two or four equally spaced units, as opposed to beats with three or more complex groupings of subdivisions. Additionally, lower pitched pulse trains were more often perceived as the beat. Our findings suggest that subdivisions, not beats, are the basic unit of beat perception, and that the principle underlying the binary grouping of subdivisions reflects a propensity towards simplicity. This preference for simple grouping is widely applicable to human perception and cognition of time.

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Saito, Yuka, Tomoki Maezawa, and Jun I. Kawahara. "Beat Patterns Determine Inter-Hand Differences in Synchronization Error in a Bimanual Coordination Tapping Task." i-Perception 12, no. 5 (September 2021): 204166952110538. http://dx.doi.org/10.1177/20416695211053882.

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A previous study reported the unique finding that people tapping a beat pattern with the right hand produce larger negative synchronization error than when tapping with the left hand or other effectors, in contrast to previous studies that have shown that the hands tap patterns simultaneously without any synchronization errors. We examined whether the inter-hand difference in synchronization error occurred due to handedness or to a specificity of the beat pattern employed in that study. Two experiments manipulated the hand–beat assignments. A comparison between the identical beat to the pacing signal and a beat with a longer interval excluded the handedness hypothesis and demonstrated that beat patterns with relatively shorter intervals were tapped earlier (Experiment 1). These synchronization errors were not local but occurred consistently throughout the beat patterns. Experiment 2 excluded alternative explanations. These results indicate that the apparent inconsistency in previous studies was due to the specificity of the beat patterns, suggesting that a beat pattern with a relatively shorter interval between hands is tapped earlier than beats with longer intervals. Our finding that the bimanual tapping of different beat patterns produced different synchronization errors suggests that the notion of a central timing system may need to be revised.

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Nasim, Amnah, Agnese Sbrollini, Micaela Morettini, and Laura Burattini. "Extended Segmented Beat Modulation Method for Cardiac Beat Classification and Electrocardiogram Denoising." Electronics 9, no. 7 (July 20, 2020): 1178. http://dx.doi.org/10.3390/electronics9071178.

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Beat classification and denoising are two challenging and fundamental operations when processing digital electrocardiograms (ECG). This paper proposes the extended segmented beat modulation method (ESBMM) as a tool for automatic beat classification and ECG denoising. ESBMM includes four main steps: (1) beat identification and segmentation into PQRS and TU segments; (2) wavelet-based time-frequency feature extraction; (3) convolutional neural network-based classification to discriminate among normal (N), supraventricular (S), and ventricular (V) beats; and (4) a template-based denoising procedure. ESBMM was tested using the MIT–BIH arrhythmia database available at Physionet. Overall, the classification accuracy was 91.5% while the positive predictive values were 92.8%, 95.6%, and 83.6%, for N, S, and V classes, respectively. The signal-to-noise ratio improvement after filtering was between 0.15 dB and 2.66 dB, with a median value equal to 0.99 dB, which is significantly higher than 0 (p < 0.05). Thus, ESBMM proved to be a reliable tool to classify cardiac beats into N, S, and V classes and to denoise ECG tracings.

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Campbell, K. B., H. Taheri, R. D. Kirkpatrick, and B. K. Slinker. "Single perturbed beat vs. steady-state beats for assessing systolic function in the isolated heart." American Journal of Physiology-Heart and Circulatory Physiology 262, no. 6 (June 1, 1992): H1631—H1639. http://dx.doi.org/10.1152/ajpheart.1992.262.6.h1631.

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Single-beat and steady-state techniques for evaluating end-systolic pressure-volume relationship (ESPVR) and Frank-Starling mechanism (FSM) in the crystalloid-perfused isolated rabbit heart were compared. In the single-beat technique, a train of stable isovolumic beats was interrupted with a single perturbed beat that either ejected against various levels of imposed isobaric load (ESPVR protocol) or beat isovolumically against various levels of end-diastolic volume (V(ED); FSM protocol). In steady-state technique, sustained beating was established, isobarically, at each of various loads (ESPVR protocol) or, isovolumically, at each of various V(ED) values (FSM protocol). ESPVR from steady-state technique lay above and to the left of that from single-beat technique. Contractile state was not uniform within steady-state technique, whereas it was uniform within single-beat technique. In the FSM protocol, single-beat technique exhibited the following features relative to steady-state technique: 1) greater range of developed pressures, 2) steeper ascending limb and more sharply defined maxima, 3) higher maximal developed pressure (Pdmax), and 4) greater volume at Pdmax(Vmax). Again. a common contractile state existed within single-beat technique but not within steady-state technique. It was concluded that single-beat technique was preferable to steady-state technique for evaluating ESPVR and FSM because 1) single-beat technique required less time for obtaining data, 2) single-beat technique allowed identification of uncomplicated values of Pdmax and Vmax, and 3) single-beat technique provided a common contractile-state reference for all data, whereas steady-state technique did not.

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Suzuki, Shunsuke, Junichi Araki, Yumiko Doi, Waso Fujinaka, Hitoshi Minami, Gentaro Iribe, Satoshi Mohri, Juichiro Shimizu, Masahisa Hirakawa, and Hiroyuki Suga. "Coupling interval from slow to tachycardiac pacing decides sustained alternans pattern." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 3 (March 1, 2001): H1368—H1375. http://dx.doi.org/10.1152/ajpheart.2001.280.3.h1368.

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We discovered that the coupling beat interval from a slow to a tachycardiac pacing period considerably affected the pattern of the beat-to-beat alternation of the tachycardia-induced sustained contractile alternans. We analyzed the relationship between the coupling interval and the pattern and amplitude of the alternans in the isovolumic left ventricle of canine blood-perfused hearts. The alternans pattern and amplitude varied transiently over the first 30–50 beats and became gradually stable over the first minute in all 12 hearts. We discovered that stable alternans, even under the same tachycardiac pacing, had three different strong-weak beat patterns depending on the coupling interval. A relatively short coupling interval produced a representative sustained alternans of the strong and weak beats. A relatively long coupling interval produced a similar sustained alternans but in a reversed order of even- and odd-numbered beats counted from the coupling interval. However, sustained alternans disappeared after 1–3 specific coupling intervals. We conclude that ventricular pacing rate does not solely determine the pattern and amplitude of sustained contractile alternans induced by tachycardia.

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Ferreira, Leonardo F., Allison J. Harper, and Thomas J. Barstow. "Frequency-domain characteristics and filtering of blood flow following the onset of exercise: implications for kinetics analysis." Journal of Applied Physiology 100, no. 3 (March 2006): 817–25. http://dx.doi.org/10.1152/japplphysiol.01036.2005.

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We examined the validity and usefulness of a low-pass filter (LPFILTER) to reduce point-to-point variability and enhance parameter estimation of the kinetics of blood flow (BF). Computer simulations were used to determine the power spectrum of simulated responses. Moreover, we studied the leg BF response to a single transition in four subjects during supine knee-extension exercise using three methods of data processing [beat-by-beat, average of 3 cardiac cycles (AVG3 BEATS), and LPFILTER]. The power spectrum of BF containing the kinetics information (≤0.2 Hz) did not overlap with the oscillations due to muscle contraction and cardiac cycle (simulations and Doppler measurements). There were no significant differences between the parameter estimates for a two-exponential model using Beat-by-Beat, AVG3 BEATS, and LPFILTER ( P > 0.05; n = 4). However, LPFILTER (cutoff = 0.2 Hz) resulted in a significantly lower standard error of the estimate for all parameters ( P < 0.05). The means ± SD for the standard error of the estimate for Beat-by-Beat, AVG3 BEATS, and LPFILTER were, respectively, time constant- phase 1 = 5.0 ± 1.1 s, 4.5 ± 2.1 s, and 0.3 ± 0.2 s; time delay- phase 2 = 17.8 ± 7.9 s, 12.8 ± 7.5 s, and 1.4 ± 1.4 s; time constant- phase 2 = 15.8 ± 4.6 s, 9.9 ± 2.9 s, and 1.1 ± 0.5 s. In conclusion, LPFILTER appeared to be a valid procedure providing a high signal-to-noise ratio and data density and thus LPFILTER resulted in the smallest confidence interval for parameter estimates of BF kinetics.

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Phua, Jason. "Heart(beat) to Heart(beat)." JAMA Cardiology 5, no. 3 (March 1, 2020): 249. http://dx.doi.org/10.1001/jamacardio.2019.5302.

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Lee, Chan-Hee, Amaan Shafi, and Melvin M. Scheinman. "Beat-to-beat QRS alternans." Heart Rhythm 20, no. 11 (November 2023): 1586–88. http://dx.doi.org/10.1016/j.hrthm.2023.03.1524.

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Xie, You-Liang, and Che-Wei Lin. "Imbalanced Ectopic Beat Classification Using a Low-Memory-Usage CNN LMUEBCNet and Correlation-Based ECG Signal Oversampling." Mathematics 11, no. 8 (April 12, 2023): 1833. http://dx.doi.org/10.3390/math11081833.

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Objective: This study presents a low-memory-usage ectopic beat classification convolutional neural network (CNN) (LMUEBCNet) and a correlation-based oversampling (Corr-OS) method for ectopic beat data augmentation. Methods: A LMUEBCNet classifier consists of four VGG-based convolution layers and two fully connected layers with the continuous wavelet transform (CWT) spectrogram of a QRS complex (0.712 s) segment as the input of the LMUEBCNet. A Corr-OS method augmented a synthetic beat using the top K correlation heartbeat of all mixed subjects for balancing the training set. This study validates data via a 10-fold cross-validation in the following three scenarios: training/testing with native data (CV1), training/testing with augmented data (CV2), and training with augmented data but testing with native data (CV3). Experiments: The PhysioNet MIT-BIH arrhythmia ECG database was used for verifying the proposed algorithm. This database consists of a total of 109,443 heartbeats categorized into five classes according to AAMI EC57: non-ectopic beats (N), supraventricular ectopic beats (S), ventricular ectopic beats (V), a fusion of ventricular and normal beats (F), and unknown beats (Q), with 90,586/2781/7236/803/8039 heartbeats, respectively. Three pre-trained CNNs: AlexNet/ResNet18/VGG19 were utilized in this study to compare the ectopic beat classification performance of the LMUEBCNet. The effectiveness of using Corr-OS data augmentation was determined by comparing (1) with/without using the Corr-OS method and (2) the Next-OS data augmentation method. Next-OS augmented the synthetic beat using the next heartbeat of one subject. Results: The proposed LMUEBCNet can achieve a 99.4% classification accuracy under the CV2 and CV3 cross-validation scenarios. The accuracy of the proposed LMUEBCNet is 0.4–0.5% less than the performance obtained from AlexNet/ResNet18/VGG19 under the same data augmentation and cross-validation scenario, but the parameter usage is only 10% or less than that of the AlexNet/ResNet18/VGG19 method. The proposed Corr-OS method can improve ectopic beat classification accuracy by 0.3%. Conclusion: This study developed a LMUEBCNet that can achieve a high ectopic beat classification accuracy with efficient parameter usage and utilized the Corr-OS method for balancing datasets to improve the classification performance.

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Gouyon, Fabien, Gerhard Widmer, Xavier Serra, and Arthur Flexer. "Acoustic Cues to Beat Induction: A Machine Learning Perspective." Music Perception 24, no. 2 (December 1, 2006): 177–88. http://dx.doi.org/10.1525/mp.2006.24.2.177.

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This article brings forward the question of which acoustic features are the most adequate for identifying beats computationally in acoustic music pieces. We consider many different features computed on consecutive short portions of acoustic signal, among which those currently promoted in the literature on beat induction from acoustic signals and several original features, unmentioned in this literature. Evaluation of feature sets regarding their ability to provide reliable cues to the localization of beats is based on a machine learning methodology with a large corpus of beat-annotated music pieces, in audio format, covering distinctive music categories. Confirming common knowledge, energy is shown to be a very relevant cue to beat induction (especially the temporal variation of energy in various frequency bands, with the special relevance of frequency bands below 500 Hz and above 5 kHz). Some of the new features proposed in this paper are shown to outperform features currently promoted in the literature on beat induction from acoustic signals.We finally hypothesize that modeling beat induction may involve many different, complementary acoustic features and that the process of selecting relevant features should partly depend on acoustic properties of the very signal under consideration.

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Chen, Xiaoxiao, Javier A. Sala-Mercado, Robert L. Hammond, Masashi Ichinose, Soroor Soltani, Ramakrishna Mukkamala, and Donal S. O'Leary. "Dynamic control of maximal ventricular elastance via the baroreflex and force-frequency relation in awake dogs before and after pacing-induced heart failure." American Journal of Physiology-Heart and Circulatory Physiology 299, no. 1 (July 2010): H62—H69. http://dx.doi.org/10.1152/ajpheart.00922.2009.

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We investigated to what extent maximal ventricular elastance ( Emax) is dynamically controlled by the arterial baroreflex and force-frequency relation in conscious dogs and to what extent these mechanisms are attenuated after the induction of heart failure (HF). We mathematically analyzed spontaneous beat-to-beat hemodynamic variability. First, we estimated Emax for each beat during a baseline period using the ventricular unstressed volume determined with the traditional multiple beat method during vena cava occlusion. We then jointly identified the transfer functions (system gain value and time delay per frequency) relating beat-to-beat fluctuations in arterial blood pressure (ABP) to Emax (ABP→ Emax) and beat-to-beat fluctuations in heart rate (HR) to Emax (HR→ Emax) to characterize the dynamic properties of the arterial baroreflex and force-frequency relation, respectively. During the control condition, the ABP→ Emax transfer function revealed that ABP perturbations caused opposite direction Emax changes with a gain value of −0.023 ± 0.012 ml−1, whereas the HR→ Emax transfer function indicated that HR alterations caused same direction Emax changes with a gain value of 0.013 ± 0.005 mmHg·ml−1·(beats/min)−1. Both transfer functions behaved as low-pass filters. However, the ABP→ Emax transfer function was more sluggish than the HR→ Emax transfer function with overall time constants (indicator of full system response time to a sudden input change) of 11.2 ± 2.8 and 1.7 ± 0.5 s ( P < 0.05), respectively. During the HF condition, the ABP→ Emax and HR→ Emax transfer functions were markedly depressed with gain values reduced to −0.0002 ± 0.007 ml−1 and −0.001 ± 0.004 mmHg·ml−1·(beats/min)−1 ( P < 0.1). Emax is rapidly and significantly controlled at rest, but this modulation is virtually abolished in HF.

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Yan, Yiton T., C. J. McKinstrie, T. Katsouleas, and J. M. Dawson. "Counterstreaming electron-beam beat-wave accelerator." Physical Review A 36, no. 11 (December 1, 1987): 5455–58. http://dx.doi.org/10.1103/physreva.36.5455.

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Tschakovsky, M. E., J. K. Shoemaker, and R. L. Hughson. "Beat-by-beat forearm blood flow with Doppler ultrasound and strain-gauge plethysmography." Journal of Applied Physiology 79, no. 3 (September 1, 1995): 713–19. http://dx.doi.org/10.1152/jappl.1995.79.3.713.

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Simultaneous Doppler ultrasound estimates of brachial artery mean blood velocity (MBV) and venous occlusion strain-gauge plethysmography measures of forearm blood flow (FBF) were performed to determine the beat-by-beat relationship between the two methods and provide a method for flow calibration of Doppler MBV estimates. Such a calibration of Doppler MBV eliminates the need for knowledge of vessel cross-sectional area and angle of insonation while allowing for the quantification of limb blood flow. Six healthy subjects (5 men and 1 woman) performed 40 s of isometric forearm contraction at 35% maximal voluntary contraction with arterial inflow occluded. This resulted in elevated blood flow on relaxation and cuff deflation, and simultaneous beat-by-beat Doppler MBV and strain-gauge FBF measurements were then made over a period of 2–3 min as flow gradually decreased to resting levels. The r2 values for the fitted regression lines over a wide range of flows ranged from 0.87 to 0.98, and the mean square error terms ranged from 0.88 to 3.07 ml.100 ml-1.min-1. Significant day-to-day variation of the fitted regression parameters within subjects indicated that quantitative estimates of FBF from Doppler MBV require a calibration to be performed for each experiment. The finding of a strong linear relationship between Doppler MBV and venous occlusion strain-gauge plethysmography, as well as the marked beat-by-beat effect of cuff inflation on blood flow, confirms the importance of calibration on the same beats, not on adjacent segments of beats.

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Wang, Ziyin, Tom Beneke, Eva Gluenz, and Richard John Wheeler. "The single flagellum of Leishmania has a fixed polarisation of its asymmetric beat." Journal of Cell Science 133, no. 20 (October 15, 2020): jcs246637. http://dx.doi.org/10.1242/jcs.246637.

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ABSTRACTEukaryotic flagella undertake different beat types as necessary for different functions; for example, the Leishmania parasite flagellum undergoes a symmetric tip-to-base beat for forward swimming and an asymmetric base-to-tip beat to rotate the cell. In multi-ciliated tissues or organisms, the asymmetric beats are coordinated, leading to movement of the cell, organism or surrounding fluid. This coordination involves a polarisation of power stroke direction. Here, we asked whether the asymmetric beat of the single Leishmania flagellum also has a fixed polarisation. We developed high frame rate dual-colour fluorescence microscopy to visualise flagellar-associated structures in live swimming cells. This showed that the asymmetric Leishmania beat is polarised, with power strokes only occurring in one direction relative to the asymmetric flagellar machinery. Polarisation of bending was retained in deletion mutants whose flagella cannot beat but have a static bend. Furthermore, deletion mutants for proteins required for asymmetric extra-axonemal and rootlet-like flagellum-associated structures also retained normal polarisation. Leishmania beat polarisation therefore likely arises from either the nine-fold rotational symmetry of the axoneme structure or is due to differences between the outer doublet decorations.

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Handegard, Nils Olav, Geir Pedersen, and Ole Brix. "Estimating tail-beat frequency using split-beam echosounders." ICES Journal of Marine Science 66, no. 6 (February 4, 2009): 1252–58. http://dx.doi.org/10.1093/icesjms/fsp003.

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Abstract Handegard, N. O., Pedersen, G., and Brix, O. 2009. Estimating tail-beat frequency using split-beam echosounders. – ICES Journal of Marine Science, 66: 1252–1258. Data from a standard split-beam echosounder are used to estimate tail-beat frequency within a dense herring (Clupea harengus L.) layer. The data were collected by lowering a horizontally projecting 38 kHz split-beam transducer into a herring layer at 245-m depth. Individual targets were concatenated into tracks, and a fast Fourier transform was used to estimate the periodogram of the backscattering strengths along each track. A simple model, assumed accurate under certain conditions, was used to relate the periodogram to tail-beat frequency. The requisite conditions are discussed. Examples of accurate tail-beat estimates from single high-quality tracks, which are consistent with statistics on all tracks in the test dataset, are presented. In addition, the cross periodogram between closely spaced individuals was calculated on selected tracks to estimate the relative phase between the adjacent tracks within the school. Finally, the potential use of this method to resolve schooling behaviour, improve target-strength estimates, and even estimate fish condition, is discussed.

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Feeny, Albert, and Larisa G. Tereshchenko. "Beat-to-beat determinants of the beat-to-beat temporal and spatial variability of repolarization." Journal of Electrocardiology 49, no. 3 (May 2016): 417–22. http://dx.doi.org/10.1016/j.jelectrocard.2016.01.007.

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Reid, John D., John R. Rohde, and Dean L. Sicking. "Box-Beam Burster Energy-Absorbing Single-Sided Crash Cushion." Transportation Research Record: Journal of the Transportation Research Board 1797, no. 1 (January 2002): 72–81. http://dx.doi.org/10.3141/1797-09.

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A new box-beam burster energy-absorbing single-sided crash cushion (BEAT-SSCC) was designed and crash tested. This energy-absorbing crash cushion is designed to shield a rigid hazard, such as the end of a concrete safety-shaped barrier. Energy-absorbing capabilities of the BEAT-SSCC are based on the bursting tube technology, similar to that used with the box-beam burster energy-absorbing terminal. Five full-scale vehicle crash tests were conducted to evaluate the impact performance of the BEAT-SSCC in accordance with guidelines set forth in NCHRP Report 350: ( a) Test Designation 3-31—pickup truck head-on test; ( b) Test Designation 3-38—pickup truck critical impact point test (two tests to evaluate two different critical impact points); ( c) Test Designation 3-39—pickup truck reverse direction test at midpoint of crash cushion, and ( d) modified Test Designation 3-39—pickup truck reverse direction test at connection to the concrete barrier. The crash cushion performed as designed, and the BEAT-SSCC meets all evaluation criteria for a Test Level 3 crash cushion set forth in NCHRP Report 350. The BEAT-SSCC is being evaluated by FHWA for approval to be used on the National Highway System.

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Tabata, Tomotsugu, Richard A. Grimm, Junko Asada, Zoran B. Popović, Hirotsugu Yamada, Neil L. Greenberg, Don W. Wallick, et al. "Determinants of LV diastolic function during atrial fibrillation: beat-to-beat analysis in acute dog experiments." American Journal of Physiology-Heart and Circulatory Physiology 286, no. 1 (January 2004): H145—H152. http://dx.doi.org/10.1152/ajpheart.00588.2003.

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Left ventricular (LV) diastolic function during atrial fibrillation (AF) remains poorly understood due to the complex interaction of factors and beat-to-beat variability. The purpose of the present study was to elucidate the physiological determinants of beat-to-beat changes in LV diastolic function during AF. The RR intervals preceding a given cardiac beat were measured from the right ventricular electrogram in 12 healthy open-chest mongrel dogs during AF. Doppler echocardiography and LV pressure and volume beat-to-beat analyses were performed. The LV filling time (FT) and early diastolic mitral inflow velocity-time integral ( Evti) were measured using the pulsed Doppler method. The LV end-diastolic volume (EDV), peak systolic LV pressure (LVP), minimum value of the first derivative of LV pressure curve (dP/d tmin), and the time constant of LV pressure decay (τ) were evaluated with the use of a conductance catheter for 100 consecutive cardiac cycles. Beat-to-beat analysis revealed a cascade of important causal relations. LV-FT showed a significant positive linear relationship with Evti ( r = 0.87). Importantly, there was a significant positive linear relationship between the RR interval and LV-EDV in the same cardiac beat ( r = 0.53). Consequently, there was a positive linear relationship between LV-EDV and subsequent peak systolic LVP ( r = 0.82). Furthermore, there were significant positive linear and negative curvilinear relationships between peak systolic LVP and dP/d tmin ( r = 0.95) and τ ( r = –0.85), respectively, in the same cardiac beat. In addition, there was a significant negative curvilinear relationship between dP/d tmin and τ ( r = –0.86). We have concluded that the determinants of LV diastolic function in individual beats during AF depend strongly on the peak systolic LVP. This suggests that the major benefit of slower ventricular rate appears related to lengthening of LV filling interval, promoting subsequent higher peak systolic LVP and greater LV relaxation.

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SCHULTZ, BENJAMIN G., IRENA O’BRIEN, NATALIE PHILLIPS, DAVID H. McFARLAND, DEBRA TITONE, and CAROLINE PALMER. "Speech rates converge in scripted turn-taking conversations." Applied Psycholinguistics 37, no. 5 (November 25, 2015): 1201–20. http://dx.doi.org/10.1017/s0142716415000545.

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ABSTRACTWhen speakers engage in conversation, acoustic features of their utterances sometimes converge. We examined how the speech rate of participants changed when a confederate spoke at fast or slow rates during readings of scripted dialogues. A beat-tracking algorithm extracted the periodic relations between stressed syllables (beats) from acoustic recordings. The mean interbeat interval (IBI) between successive stressed syllables was compared across speech rates. Participants’ IBIs were smaller in the fast condition than in the slow condition; the difference between participants’ and the confederate's IBIs decreased across utterances. Cross-correlational analyses demonstrated mutual influences between speakers, with greater impact of the confederate on participants’ beat rates than vice versa. Beat rates converged in scripted conversations, suggesting speakers mutually entrain to one another's beat.

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Berger, David S., Katherine Vlasica, Christopher M. Quick, Kimberly A. Robinson, and Sanjeev G. Shroff. "Ejection has both positive and negative effects on left ventricular isovolumic relaxation." American Journal of Physiology-Heart and Circulatory Physiology 273, no. 6 (December 1, 1997): H2696—H2707. http://dx.doi.org/10.1152/ajpheart.1997.273.6.h2696.

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In isovolumically beating hearts, the speed of left ventricular (LV) relaxation is uniquely determined by peak active stress (ςmax). In contrast, such a succinct description of relaxation is lacking for the ejection beats, although ejection is generally thought to hasten relaxation. We set out to determine how ejection modifies the relaxation-ςmax relationship obtained in the isovolumically beating hearts. Experiments were performed on five isolated rabbit hearts subjected to various loading conditions. Instantaneous LV pressure and volume were recorded and converted to active stress, from which isovolumic relaxation time ( T r) was defined as the time for stress to fall from 75 to 25% of ςmax (isovolumic beats) or its end-ejection value (ejection beats). Steady-state and transient isovolumic beat and steady-state ejection beat data were used to develop a multiple regression model. This model identified stress, current beat ejection, and previous beat ejection history as independent predictor variables of T r and fit the data well in all hearts ( r 2 > 0.98). Furthermore, this model could predict relaxation in transient ejection beats ( r 2 = 0.80 for all hearts). Whereas the coefficient for the current beat ejection was negative (i.e., negative effect or hastening relaxation), the ejection history coefficient was positive (i.e., positive effect or slowing relaxation). The sum of these two coefficients was negative, corresponding to the commonly observed net negative effect of ejection on relaxation. The expected positive inotropic effect of ejection was also observed. The dissipations of both positive inotropic and relaxation effects were slow, suggesting a nonmechanical underlying mechanism(s). We postulate that these two effects are linked and caused by ejection-mediated changes in myofilament Ca2+ sensitivity.

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Ahmed, Solaiman, Tanveer Ahmed Bhuiyan, and Manabu Nii. "PPG Signal Morphology-Based Method for Distinguishing Stress and Non-Stress Conditions." Journal of Advanced Computational Intelligence and Intelligent Informatics 26, no. 1 (January 20, 2022): 58–66. http://dx.doi.org/10.20965/jaciii.2022.p0058.

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In this study, the morphology of the PPG signal has been analyzed to be a potential cardiovascular marker for physiological stress. The morphology of the PPG signal was quantified as signal quality index by comparing the template beat (extracted from resting conditions) to the PPG beats recorded during vigorous physical activity. Data was taken from eight subjects where they performed some physical activities ranging from low to high intensity. It was found that, the mean and standard deviation of correlation coefficient between non-stress condition template beat and annotated PPG beat, 89.43±5.17 (%) and 44.23±10.48 (%) for non-stress and stress beat respectively with P value of 2.04*10-06 shows significantly difference between correlation coefficients (stress and non-stress). Whereas, mean and standard deviation of dynamic time warping correlation coefficients are 93.43±5.06 (%) and 85.93±4.18 (%) for non-stress and stress beat respectively with P value of .04. The morphology results corroborate the findings from the traditional HRV parameters generally used for stratifying stress.

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Journal, IJSREM. "Beat Detection and Classification for Music Production Using RNN-LSTM Algorithm." INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, no. 02 (February 8, 2024): 1–13. http://dx.doi.org/10.55041/ijsrem28538.

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The process of creating music involves various techniques, including beat detection and classification. This research paper proposes a novel approach to detecting and classifying beats in music production using a recurrent neural network with long short-term memory (RNN-LSTM) algorithm. The proposed method uses a set of features that are extracted from the audio signal, including spectral flux, zero- crossing rate, and energy, to train the RNN-LSTM model. The model is trained using a large dataset of music tracks and is capable of predicting the beats and their respective classifications accurately. The proposed approach was evaluated on a dataset of various music genres, and the results showed that the RNN-LSTM algorithm outperforms traditional beat detection and classification techniques. The algorithm achieved an high accuracy as compared to the traditional techniques. Additionally, the proposed method is capable of detecting and classifying beats in real-time, making it useful formusic production applications. The proposed approach has several potential applications, including music production, DJing, and music analysis. It can be used to identify the beats ina song, which can be used to synchronize different tracks, createremixes, and enhance the overall listening experience. Furthermore, the proposed method can be used to analyze the characteristics of different music genres and identify the underlying patterns that define them. Keywords— Beat Detection, Beat Classification, Music Production, RNN-LSTM algorithm, Music Analysis.

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Ruth-Hirrel, Laura, and Sherman Wilcox. "Speech-gesture constructions in cognitive grammar: The case of beats and points." Cognitive Linguistics 29, no. 3 (August 28, 2018): 453–93. http://dx.doi.org/10.1515/cog-2017-0116.

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AbstractThe current study uses principles from Cognitive Grammar to better account for the symbolic integration of gesture and speech. Drawing on data collected from language use, we examine the use of two attention-directing strategies that are expressed through gesture, beats and pointing. It has been claimed that beats convey no semantic information. We propose that beat gestures are symbolic structures. It has also been noted that beats are often overlaid on other gestures. To date, however, no detailed explanation has been offered to account for the conceptual and phonological integration of beats with other co-expressed gestures. In this paper, we explore the integration of beats and pointing gestures as complex gestural expressions. We find that simple beat gestures, as well as beat gestures co-expressed with pointing gestures, are used to direct attention to meanings in speech that are associated with salient components of stancetaking acts. Our account further reveals a symbolic motivation for the apparent “superimposing” of beats onto pointing gestures. By closely examining actual usage events, we take an initial step toward demonstrating how the symbolic elements of both beats and points are integrated in multimodal constructions.

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Chen, T. Y., D. D. Grant, M. F. Lau, S. P. Ng, and V. R. Vasa. "BEAT." International Journal of Distance Education Technologies 4, no. 2 (April 2006): 44–56. http://dx.doi.org/10.4018/jdet.2006040104.

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Hubner, Patrick. "BEAT." Babel, no. 39 (June 1, 2019): 243–44. http://dx.doi.org/10.4000/babel.7383.

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Cherry, James E. "Beat." Callaloo 25, no. 1 (2002): 217. http://dx.doi.org/10.1353/cal.2002.0007.

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Freeman, G. L., L. E. Widman, J. M. Campbell, and J. T. Colston. "An evaluation of pulsus alternans in closed-chest dogs." American Journal of Physiology-Heart and Circulatory Physiology 262, no. 1 (January 1, 1992): H278—H284. http://dx.doi.org/10.1152/ajpheart.1992.262.1.h278.

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Pulsus alternans is a condition in which the arterial pressure generated by the heart oscillates between two levels on a beat-to-beat basis. We evaluated the onset of pulsus alternans in chronically instrumented dogs subjected to tachycardia and inferior vena caval occlusion. During pulsus alternans, the left ventricular (LV) end-diastolic volume (EDV) was larger before the strong beats (28.7 +/- 5.3 vs. 25.9 +/- 4.5 ml, P less than 0.001 by paired t test), suggesting that the Frank-Starling mechanism participates in the alternating difference in end-systolic pressure. In addition, however, the ratio of pressure to volume at end systole was greater in the strong beats (2.01 +/- 0.36 vs. 1.46 +/- 0.45, P less than 0.005 by paired t test), a difference that cannot be explained by the Frank-Starling mechanism alone. This indicates that there is also a difference in end-systolic inotropic states between strong and weak beats. These changes occurred without significant alterations in beat-to-beat levels of coronary flow. The time constant of isovolumic pressure fall (T) was faster for the strong beats (37.5 +/- 4.2 vs 61.1 +/- 12.7 ms, P less than 0.002 by paired t test). The onset of oscillation in T preceded the onset of changes in LVEDV and LV systolic pressure in every case by an average of seven beats (range 3-11), suggesting that abnormalities of intracellular calcium handling led to the occurrence of pulsus alternans.(ABSTRACT TRUNCATED AT 250 WORDS)

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Berger, Ronald D., Edward K. Kasper, Kenneth L. Baughman, Eduardo Marban, Hugh Calkins, and Gordon F. Tomaselli. "Beat-to-Beat QT Interval Variability." Circulation 96, no. 5 (September 2, 1997): 1557–65. http://dx.doi.org/10.1161/01.cir.96.5.1557.

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Mahajan, Aman, and Nir Hoftman. "To Beat or Not to Beat." Anesthesiology 113, no. 4 (October 1, 2010): 765–66. http://dx.doi.org/10.1097/aln.0b013e3181eaa795.

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Johansson, Bengt W. "TO BEAT OR NOT TO BEAT." Acta Medica Scandinavica 195, no. 1-6 (April 24, 2009): 1–3. http://dx.doi.org/10.1111/j.0954-6820.1974.tb08084.x.

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FLOWERS, NANCY C., LEO G. HORAN, and WEIQUN YANG. "Application of Beat-to-Beat Techniques." Pacing and Clinical Electrophysiology 13, no. 12 (December 1990): 2148–55. http://dx.doi.org/10.1111/j.1540-8159.1990.tb06958.x.

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Vermeiren, Chr, Cl Médigue, J. Clairambault, and L. Curzi-Dascalova. "Beat-to-Beat Cardio-Respiratory Demodulation." IFAC Proceedings Volumes 27, no. 1 (March 1994): 147–48. http://dx.doi.org/10.1016/s1474-6670(17)46187-8.

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Ramphele, M. A. "Adolescents and violence: “Adults are cruel, they just beat, beat, beat!”." Social Science & Medicine 45, no. 8 (October 1997): 1189–97. http://dx.doi.org/10.1016/s0277-9536(97)00025-7.

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Fujimoto, Naoki, Shigeki Shibata, Jeffery L. Hastings, Graeme Carrick-Ranson, Paul S. Bhella, Dean Palmer, Qi Fu, and Benjamin D. Levine. "Effects of pericardial constraint and ventricular interaction on left ventricular hemodynamics in the unloaded heart." American Journal of Physiology-Heart and Circulatory Physiology 300, no. 5 (May 2011): H1688—H1695. http://dx.doi.org/10.1152/ajpheart.01198.2010.

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Pericardial constraint and ventricular interaction influence left ventricular (LV) performance when preload is high. However, it is unclear if these constraining forces modulate LV filling when the heart is unloaded, such as during upright posture, in humans. Fifty healthy individuals underwent right heart catheterization to measure pulmonary capillary wedge (PCWP) and right atrial pressure (RAP). To evaluate the effects of pericardial constraint on hemodynamics, transmural filling pressure (LVTMP) was defined as PCWP-RAP. Beat-to-beat blood pressure (BP) waveforms were recorded, and stroke volume (SV) was derived from the Modelflow method. After measurements at −30 mmHg lower body negative pressure (LBNP), which approximates the upright position, LBNP was released, and beat-to-beat measurements were performed for 15 heartbeats. At −30 mmHg LBNP, RAP and PCWP were significantly decreased. During the first six beats of LBNP release, heart rate (HR) was unchanged, while BP increased from the fourth beat. RAP increased faster than PCWP resulting in an acute decrease in LVTMP from the fourth beat. A corresponding drop in SV by 3% was observed with no change in pulse pressure. From the 7th to 15th beats, LVTMP and SV increased steadily, followed by a decreased HR due to the baroreflex. A decreased TMP, but not PCWP, caused a transient drop in SV with no changes in HR or pulse pressure during LBNP release. These results suggest that the pericardium constrains LV filling during LBNP release, enough to cause a small but significant drop of SV, even at low cardiac filling pressure in healthy humans.

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Hokkanen, Jyrki E. I., and M. Edwin DeMont. "Complex dynamics in the heart of the lobster Homarus americanus." Canadian Journal of Zoology 75, no. 5 (May 1, 1997): 746–54. http://dx.doi.org/10.1139/z97-096.

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Nonlinear dynamics have been shown to be important in describing a large number of complex physiological systems. This work examined the dynamics of the relatively simple neurogenic heart of the lobster Homarus americanus. A non-invasive device was used to collect continuous data of spontaneous heart beats, and time series of consecutive beat-to-beat intervals were generated from these data. This study was concerned with dynamic changes in beat-to-beat intervals that were induced by external effects including changes in both the level of activity and body temperature. Two types of temperature changes, short term (acute) and long term (chronic), were examined. In both cases, decreasing the ambient temperature increased the mean interval length as well as the variation. The regression slope of the correlation between the mean and the variation was unique for each lobster. Variation around the mean included periodic components. Not only the magnitude of the variation but also its complexity were affected by temperature. Approximate entropy increased as temperature decreased, implying temperature dependence of the regularity of the beat-to-beat intervals. We suggest that future physiological studies focus on attempts to understand changes in the complexity of physiological processes.

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Das, Manab Kumar, and Samit Ari. "ECG Beats Classification Using Mixture of Features." International Scholarly Research Notices 2014 (September 17, 2014): 1–12. http://dx.doi.org/10.1155/2014/178436.

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Classification of electrocardiogram (ECG) signals plays an important role in clinical diagnosis of heart disease. This paper proposes the design of an efficient system for classification of the normal beat (N), ventricular ectopic beat (V), supraventricular ectopic beat (S), fusion beat (F), and unknown beat (Q) using a mixture of features. In this paper, two different feature extraction methods are proposed for classification of ECG beats: (i) S-transform based features along with temporal features and (ii) mixture of ST and WT based features along with temporal features. The extracted feature set is independently classified using multilayer perceptron neural network (MLPNN). The performances are evaluated on several normal and abnormal ECG signals from 44 recordings of the MIT-BIH arrhythmia database. In this work, the performances of three feature extraction techniques with MLP-NN classifier are compared using five classes of ECG beat recommended by AAMI (Association for the Advancement of Medical Instrumentation) standards. The average sensitivity performances of the proposed feature extraction technique for N, S, F, V, and Q are 95.70%, 78.05%, 49.60%, 89.68%, and 33.89%, respectively. The experimental results demonstrate that the proposed feature extraction techniques show better performances compared to other existing features extraction techniques.

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Journal articles on the topic 'Beat'

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