Search results for " Beat"

Visualization of Simulated Arrhythmias due to Gap Junctions

2018

New computational models are able to simulate details of cardiac cell networks. Their results allow a better understanding of the functionality of the heart and suggest possible actions to reduce non-fatal premature beats that can give rise to serious diseases. We developed a user-friendly interface to organize Neuron simulations and to present in real-time a three-dimensional representation of the electrical activity due to the gap junctions which interconnect the cells inside cardiac tissues. All physiological parameters were set according to real experimental observations and compared against different types of arrhythmias, retrieved from the Physionet Data Base.

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…

Dones i ciència. Quatre pioneres en el camp de la psicologia

2012

Una carrera científica normalment és una carrera d'obstacles, però en el cas de ser una dona s’afegeixen problemes i mecanismes d'exclusió específics.  Per tal de conèixer les estratègies utilitzats per superar alguns obstacles, al present article revisem les biografies de quatre psicòlogues que, entre 1890 i 1940, van intentar obtenir una formació acadèmica i van aconseguir fer una contribució pròpia a la ciència psicològica.

Effect of sulfur dioxide on mucociliary activity and ciliary beat frequency in guinea pig trachea

1994

The effects of 30 min exposure to sulfur dioxide on mucociliary activity (MCA) and ciliary beat frequency (CBF) were studied in 31 guinea pig tracheas. MCA was measured by recording the light reflected from ciliated mucous membranes using an infrared bar code reader. CBF of single ciliated cells obtained by brushing was measured with phase-contrast microscopy. Each tracheal sample was exposed to SO2 at concentrations ranging from 2.5 to 12.5 ppm, or to air for control purposes. MCA and CBF were measured before and immediately after gas exposure. A reduction in mean MCA of 63% (P = 0.0007) and statistically insignificant changes in CBF (P > 0.05) were recorded at concentrations of 2.5 PPM SO…

A Ciliary Motility Index for Activity Measurement in Cell Cultures With Respiratory Syncytial Virus

2018

[EN] Background: The respiratory epithelium is frequently infected by the respiratory syncytial virus, resulting in inflammation, a reduction in cilia activity and an increase in the production of mucus. Methods: In this study, an automatic method has been proposed to characterize the ciliary motility from cell cultures by means of a motility index using a dense optical flow algorithm. This method allows us to determine the ciliary beat frequency (CBF) together with a ciliary motility index of the cells in the cultures. The object of this analysis is to automatically distinguish between normal and infected cells in a culture. Results: The method was applied in 2 stages. It was concluded fro…

Nuclear Spins of the IsomersHg191m−185mDetermined by On-Line Quantum-Beat Spectroscopy

1979

The nuclear spins of the very neutron-deficient $^{191m\ensuremath{-}185m}\mathrm{Hg}$ isomers were measured on line at the mass separator ISO LIDE at CERN using pulsed-laser excitation and observation of the time-resolved quantum beats from selected hyperfine-structure states. The spins of these isomers are with $I=\frac{13}{2}$ equal to those of the long-lived isomers $^{199m\ensuremath{-}193m}\mathrm{Hg}$ already known. The persistence of this spin value for eight isomers is explained by the model of rotation-aligned coupling.

Femtosecond coherent anti-Stokes Raman-scattering polarization beat spectroscopy of I2–Xe complex in solid krypton

2006

Time-resolved coherent anti-Stokes Raman-scattering (CARS) measurements are carried out to study the interaction between xenon atom and iodine molecule in a solid krypton matrix. Interference between the CARS polarizations of the "free" and complexed iodine molecules is observed, while the quantum beats of the complex are not detected due to low concentration. Vibrational analysis based on the polarization beats yields accurate molecular constants for the I2-Xe complex. The harmonic frequency of the I2-Xe complex is found to be redshifted by 0.90 cm-1 when compared to the free I2, whereas the anharmonicity is approximately the same. The dephasing rate of the complex is found to be somewhat …

Gozos al B.̆ Nicolás Factór, cuyas reliquias descansan en el Convento de Santa Maria de Jesus, extramuros de Valencia

1750

El full orlat Grav. xil. enmarcat del beat, flanquejat per gerros amb flors Text del goig a tres col. separades per filets

Sanctissimi Domini Nostri Domini Clementis ... Papae XI Beatificatio Servi Dei Joannis Francisci Regis Sacerdotis professi Societatis Jesu, eiusque M…

Inclou: Sanctissimi Domini Nostri Domini Clementis ... Papae XI Beatificatio Servi Dei Joannis Francisci Regis Sacerdotis professi Societatis Jesu, eiusque Missae, & Officij certis in locis concessio Caplletra ornada Sign.: ¶-¶¶2. - Els f. de la segona part dels quaderns, tenen respectivament les signatures: ¶ i ¶¶ Reclams

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…