scholarly journals Reproducibility study of the Fabbri et al. 2017 model of the human sinus node action potential

Physiome ◽  
2021 ◽  
Author(s):  
Nima Afshar ◽  
Alan Fabbri ◽  
Stefano Severi ◽  
Alan Garny ◽  
David Nickerson

The sinoatrial node (SAN) is the natural pacemaker of the mammalian heart. It has been the subject of several mathematical studies, aimed at reproducing its electrical response under normal sinus rhythms, as well as under various conditions. Such studies were traditionally done using data from rabbit SAN cells. More recently, human SAN cell data have become available, resulting in the publication of a human SAN cell model (Fabbri et al., 2017), along with its CellML version. Here, we used the CellML file provided by the model authors, together with some SED-ML files and Python scripts that we created to reproduce the main results of the aforementioned modeling study. EDITOR'S NOTE (v2): this article and its OMEX archive are republished with technical changes made to the corresponding Python scripts to remove a run-time error message displayed when executing each simulation.

Physiome ◽  
2021 ◽  
Author(s):  
Nima Afshar ◽  
Alan Fabbri ◽  
Stefano Severi ◽  
Alan Garny ◽  
David Nickerson

The sinoatrial node (SAN) is the natural pacemaker of the mammalian heart. It has been the subject of several mathematical studies, aimed at reproducing its electrical response under normal sinus rhythms, as well as under various conditions. Such studies were traditionally done using data from rabbit SAN cells. More recently, human SAN cell data have become available, resulting in the publication of a human SAN cell model (Fabbri et al., 2017), along with its CellML version. Here, we used the CellML file provided by the model authors, together with some SED-ML files and Python scripts that we created to reproduce the main results of the aforementioned modeling study. EDITOR'S NOTE (v2): this article and its OMEX archive are republished with technical changes made to the corresponding Python scripts to remove a run-time error message displayed when executing each simulation.


Physiome ◽  
2021 ◽  
Author(s):  
Nima Afshar ◽  
Alan Fabbri ◽  
Stefano Severi ◽  
Alan Garny ◽  
David Nickerson

The sinoatrial node (SAN) is the natural pacemaker of the mammalian heart. It has been the the subject of several mathematical studies, aimed at reproducing its electrical response under normal sinus rhythms, as well as under various conditions. Such studies were traditionally done using data from rabbit SAN cells. More recently, human SAN cell data have become available, resulting in the publication of a human SAN cell model (Fabbri et al., 2017), along with its CellML version. Here, we used the CellML file provided by the model authors, together with some SED-ML files and Python scripts that we created to reproduce the main results of the aforementioned modeling study.


2013 ◽  
Vol 392 ◽  
pp. 725-729 ◽  
Author(s):  
Rafael José Gomes de Oliveira ◽  
Mauro Hugo Mathias

The application of the HFRT (High-Frequency Resonance Technique), a demodulation based technique, is a technique for evaluation the condition of bearings and other components in rotating machinery. Another technique MED (Minimum Entropy Deconvolution) has been the subject of recent developments for application in condition monitoring of gear trains and roller bearings. This article demonstrates the effectiveness of the combined application of the MED technique with HFRT in order to enhance the capacity of HFRT to identify the characteristic fault frequencies of damaged bearings by increasing the signal impulsivity. All tests were done using data collected from an experimental test bench in laboratory. The Kurtosis value is used as an indicator of effectiveness of the combined technique and the results shown an increase of five times the original kurtosis value with the application of MED filter together with the HFRT.


1999 ◽  
Vol 90 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Michael D. Sharpe ◽  
Daniel J. Cuillerier ◽  
John K. Lee ◽  
Magdi Basta ◽  
Andrew D. Krahn ◽  
...  

Background The effects of sevoflurane on the electrophysiologic properties of the human heart are unknown. This study evaluated the effects of sevoflurane on the electrophysiologic properties of the normal atrioventricular conduction system, and on the accessory pathways in patients with Wolff-Parkinson-White syndrome, to determine its suitability as an anesthetic agent for patients undergoing ablative procedures. Methods Fifteen patients with Wolff-Parkinson-White syndrome undergoing elective radiofrequency catheter ablation were studied. Anesthesia was induced with alfentanil (20-50 microg/kg) and midazolam (0.15 mg/kg), and vecuronium (20 mg) and maintained with alfentanil (0.5 to 2 microg x kg(-1) x min(-1)) and midazolam (1 or 2 mg every 10-15 min, as required). An electrophysiologic study measured the effective refractory period of the right atrium, atrioventricular node, and accessory pathway; the shortest conducted cycle length of the atrioventricular node and accessory pathway during atrial pacing; the effective refractory period of the right ventricle and accessory pathway; and the shortest retrograde conducted cycle length of the accessory pathway during ventricular pacing. Parameters of sinoatrial node function included sinus node recovery time, corrected sinus node recovery time, and sinoatrial conduction time. Intraatrial conduction time and the atrial-His interval were also measured. Characteristics of induced reciprocating tachycardia, including cycle length, atrial-His, His-ventricular, and ventriculoatrial intervals, also were measured. Sevoflurane was administered to achieve an end-tidal concentration of 2% (1 minimum alveolar concentration), and the study measurements were repeated. Results Sevoflurane had no effect on the electrophysiologic parameters of conduction in the normal atrioventricular conduction system or accessory pathway, or during reciprocating tachycardia. However, sevoflurane caused a statistically significant reduction in the sinoatrial conduction time and atrial-His interval but these changes were not clinically important. All accessory pathways were successfully identified and ablated. Conclusions Sevoflurane had no effect on the electrophysiologic nature of the normal atrioventricular or accessory pathway and no clinically important effect on sinoatrial node activity. It is therefore a suitable anesthetic agent for patients undergoing ablative procedures.


Author(s):  
Dimiter Toshkov

AbstractThe link between age and happiness has been the subject of numerous studies. It is still a matter of controversy whether the relationship is U-shaped, with happiness declining after youth before bouncing back in old age, or not. While the effect of age has been examined conditional on income and other socio-demographic variables, so far, the interactions between age and income have remained insufficiently explored. Using data from the European Social Survey, this article shows that the nature of the relationship between age and happiness varies strongly with different levels of relative income. People in the lowest decile of the income distribution experience a ‘hockey stick’: a deep decline in self-reported happiness until around age 50–55 and a small bounce back in old age. The classic U-curve is found mostly in the middle-income ranks. For people at the top of the income distribution, average happiness does not vary much with age. These results demonstrate the important role of income in moderating the relationship between age and happiness.


2018 ◽  
Vol 2 (4) ◽  
Author(s):  
S. M. Dhawan ◽  
B.M. Gupta ◽  
Sudhanshu Bhusan

The paper maps quantum computing research on various publication and citation indicators, using data from Scopus database covering 10-year period 2007-16. Quantum computing research cumulated 4703 publications in 10 years, registered a slow 3.39% growth per annum, and averaged 14.30 citations per paper during the period. Top 10 countries dominate the field with 93.15% global publications share. The USA accounted for the highest 29.98% during the period. Australia tops in relative citation index (2.0).  International collaboration has been a major driver of research in the subject; 14.10% to 62.64% of national level output of top 10 countries appeared as international collaborative publications. Computer Science is one of the most popular areas of research in quantum computing research. The study identifies top 30 most productive organizations and authors, top 20 journals reporting quantum computing research, and 124 highly cited papers with 100+ citations per paper.


2009 ◽  
pp. 1583-1590
Author(s):  
Ruth Woodfield

In the late 1970s, women’s progress and participation in the more traditional scientific and technical fields, such as physics and engineering, was slow, prompting many feminist commentators to conclude that these areas had developed a nearunshakeable masculine bias. Although clearly rooted in the domains of science and technology, the advent of the computer was initially seen to challenge this perspective. It was a novel kind of artefact, a machine that was the subject of its own newly created field: “computer science” (Poster, 1990, p. 147). The fact that it was not quite subsumed within either of its parent realms led commentators to argue that computer science was also somewhat ambiguously positioned in relation to their identity as masculine. As such, it was claimed that its future trajectory as equally masculine could not be assumed, and the field of computing might offer fewer obstacles and more opportunities for women than they had experienced before. Early predictions of how women’s role in relation to information technology would develop were consequently often highly optimistic in tone. Computing was hailed as “sex-blind and colour-blind” (Williams, Cited in Griffths 1988, p. 145; see also Zientara, 1987) in support of a belief that women would freely enter the educational field, and subsequently the profession, as the 1980s advanced. During this decade, however, it became increasingly difficult to deny that this optimism was misplaced. The numbers of females undertaking undergraduate courses in the computer sciences stabilised at just over a fifth of each cohort through the 1980s and 1990s, and they were less likely to take them in the more prestigious or researchbased universities (Woodfield, 2000). Tracy Camp’s landmark article “The Incredible Shrinking Pipeline” (1997), using data up to 1994, plotted the fall-off of women in computer science between one educational level and the next in the US. It noted that “a critical point” was the drop-off before bachelor-level study—critical because the loss of women was dramatic, but also because a degree in computer science is often seen as one of the best preparatory qualifications for working within a professional IT role1. The main aim of this article is to examine how the situation has developed since 1994, and within the UK context. It will also consider its potential underlying causes, and possible routes to improvement.


Author(s):  
Kai R. Larsen ◽  
Daniel S. Becker

After preparing your dataset, the business problem should be quite familiar, along with the subject matter and the content of the dataset. This section is about modeling data, using data to train algorithms to create models that can be used to predict future events or understand past events. The section shows where data modeling fits in the overall machine learning pipeline. Traditionally, we store real-world data in one or more databases or files. This data is extracted, and features and a target (T) are created and submitted to the “Model Data” stage (the topic of this section). Following the completion of this stage, the model produced is examined (Section V) and placed into production. With the model in the production system, present data generated from the real-world environment is inputted into the system. In the example case of a diabetes patient, we enter a new patient’s information electronic health record into the system, and a database lookup retrieves additional data for feature creation.


ESC CardioMed ◽  
2018 ◽  
pp. 1940-1943
Author(s):  
Antonio Zaza

The sinoatrial node (SAN) is the dominant pacemaker structure in the mammalian heart. It is endowed with robust intrinsic automaticity, providing periodic electrical excitation with a cycle widely modulated by autonomic influences. A number of membrane channels and transporters contribute to the net membrane current supporting SAN electrical activity, whose periodicity is determined by the interplay of two oscillators termed ‘membrane’ and ‘calcium’ clock respectively. This chapter describes the structure of the SAN, the peculiarities of its electrical cycle, the nature and modulation of the underlying clocks, and SAN interaction with atrial muscle. Moreover, the features and determinants of the temporal variability of the pacemaker cycle, clinically used to assess autonomic balance, are briefly discussed.


Author(s):  
Ruth Woodfield

In the late 1970s, women’s progress and participation in the more traditional scientific and technical fields, such as physics and engineering, was slow, prompting many feminist commentators to conclude that these areas had developed a near-unshakeable masculine bias. Although clearly rooted in the domains of science and technology, the advent of the computer was initially seen to challenge this perspective. It was a novel kind of artefact, a machine that was the subject of its own newly created field: “computer science” (Poster, 1990, p. 147). The fact that it was not quite subsumed within either of its parent realms led commentators to argue that computer science was also somewhat ambiguously positioned in relation to their identity as masculine. As such, it was claimed that its future trajectory as equally masculine could not be assumed, and the field of computing might offer fewer obstacles and more opportunities for women than they had experienced before. Early predictions of how women’s role in relation to information technology would develop were consequently often highly optimistic in tone. Computing was hailed as “sex-blind and colour-blind” (Williams, Cited in Griffths 1988, p. 145; see also Zientara, 1987) in support of a belief that women would freely enter the educational field, and subsequently the profession, as the 1980s advanced. During this decade, however, it became increasingly difficult to deny that this optimism was misplaced. The numbers of females undertaking undergraduate courses in the computer sciences stabilised at just over a fifth of each cohort through the 1980s and 1990s, and they were less likely to take them in the more prestigious or research-based universities (Woodfield, 2000). Tracy Camp’s landmark article “The Incredible Shrinking Pipeline” (1997), using data up to 1994, plotted the fall-off of women in computer science between one educational level and the next in the US. It noted that “a critical point” was the drop-off before bachelor-level study—critical because the loss of women was dramatic, but also because a degree in computer science is often seen as one of the best preparatory qualifications for working within a professional IT role1. The main aim of this article is to examine how the situation has developed since 1994, and within the UK context. It will also consider its potential underlying causes, and possible routes to improvement.


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