Search results for "heart beat"
showing 7 items of 7 documents
Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics
2017
Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…
Modeling Drug Effects on Personalized 3D Models of the Heart: A Simulation Study
2010
[EN] The use of anti-arrhythmic drugs is common to treat heart rhythm disorders. Computational modeling and simulation are powerful tools that can be used to investigate the effects of specific drugs on cardiac electrophysiology. In this work a patient-specific anatomical heart model is built to study the effects of dofetilide, a drug that affects IKr current in cardiac cells. We study the multi-scale effects of the drug, from cellular to organ level, by simulating electrical propagation on tissue coupled cellular ion kinetics for several heart beats. Different cell populations configurations namely endocardial, midmyocardial and epicardial are used to test the effect of tissue heterogeneit…
Patterns of Reversal in the Heart of Ciona Intestinalis L.
1969
The reversal of the heart beat is not exclusive to tunicates, for Marcello Malpighi in 1660 described periodic reversal in Bombyx mori and in some Orthoptera. In 1821 Kuhl and van Hasselt reported the phenomenon in Ciona intestinalis L. We have observed reversal in many active pulsating blood vessels, both in vertebrates and in invertebrates, and even in embryonic heart tubes. Using four or five suction electrodes simultaneously, we were able to record electrical activity from multiple sites. Normally, the contraction wave originates from a localized site at one end of the tube and then traverses the whole length of the heart. When a wave of excitation does not propagate the full length, th…
GDL90fuzz: Fuzzing - GDL-90 Data Interface Specification Within Aviation Software and Avionics Devices–A Cybersecurity Pentesting Perspective
2022
As the core part of next-generation air transportation systems, the Automatic Dependent Surveillance-Broadcast (ADS-B) is becoming very popular. However, many (if not most) ADS-B devices and implementations support and rely on Garmin’s GDL-90 protocol for data exchange and encapsulation. In this paper, we research GDL-90 protocol fuzzing options and demonstrate practical Denial-of-Service (DoS) attacks on popular Electronic Flight Bag (EFB) software operating on mobile devices. For this purpose, we specifically configured our own avionics pentesting platform. and targeted the popular Garmin’s GDL-90 protocol as the industry-leading devices operate on it. We captured legitimate traffic from …
Review of immediate cardiac response in intertidal gastropods limpets at varying temperature, salinity and air exposure
2009
In 1990 Depledge and Andresen developed a #eld/laboratory, non-invasive technique to monitor the immediate response of cardiac activity in bivalves. Since then, several researchers have experienced and tested the variability of heart beat rate (HBR)and of associated metabolic rates under di$erent conditions in intertidal molluscs. Review of HBR immediate response in acute exposure and acclimation to changes of salinity, thermal stressors and air exposure were examined to test di$erent hypothesis. In intertidal Mediterranean and tropical limpets, the decrease in metabolic rate with a decrease in salinity was di$erent in animals experiencing di$erent degrees of salinity !uctuation in their re…
Heart beat rate: a physiological response to thermal stress in blue mussels species.
2009
Non-native species often have ecological impacts on invaded communities. The quanti#cation of features of invaders and recipient ecosystems facilitating and/or interfering with successful invasion remains a challenge because of several factors may in!uence the success of invasions. Among them, life history strategies (e.g., reproductive potential, body size), ability to avoid predators, disease resistance and physiological compensatory mechanisms to adapt to changing habitats are among the most important factors. The latter has been often invoked as the key to success for many intertidal invasive invertebrates and have been suggested as key indicators of invasibility rate and the ultimate d…
Pancreatic islets from non-heart beating donor pig: Two-layer preservation method in an in vitro porcine model
2011
Purpose Pancreata from non-heart beating donors could represent an unlimited source of islets if their cell viability can be efficiently preserved during the time necessary to process the organs by the use of a better solution of preservation compared to the classic University of Wisconsin solution. The aim of this study was to determine whether it is possible to obtain functioning “alive islets” from non-heart-beating donors by comparing, on a porcine model, the classic “UW ice-store” method with a two-layer cold storage method (TLM) using oxygenated Perfluorocarbons (PFC) and UW. Methods Whole pancreata were harvested from 20 NHBDs female pigs with similar characteristics and preserved fo…