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Sample records for cardiac electrical storm

  1. Successful treatment of cardiac electrical storm in dilated cardiomyopathy using esmolol: A case report.

    PubMed

    Li, L I; Zhou, Yuan-Li; Zhang, Xue-Jing; Wang, Hua-Ting

    2016-07-01

    The present study reports a case of electrical storm occurring in a 43-year-old woman with dilated cardiomyopathy. The patient suffered from a cardiac electrical storm, with 98 episodes of ventricular tachycardia rapidly degenerating to ventricular fibrillation in hospital. The patient was converted with a total of 120 defibrillations. Recurrent ventricular tachycardia/fibrillation was initiated by premature ventricular beats. The patient did not respond to the use of amiodaronum. However, the administration of esmolol stabilized the patient's heart rhythm. A moderate dose of the β-blocker esmolol, administered as an 0.5-mg intravenous bolus injection followed by an infusion at a rate of 0.15 mg/kg/min, inhibited the recurrence of ventricular fibrillation and normalized the electrocardiographic pattern. The results suggest that esmolol may be able to improve the survival rate of patients with electrical storm in dilated cardiomyopathy and should be considered as a primary therapy in the management of cardiac electrical storms.

  2. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Arnold, R. T.; Rust, W. D.

    1984-01-01

    Successful ground truth support of U-2 overflights was been accomplished. Data have been reduced for 4 June 1984 and some of the results have been integrated into some of MSFC's efforts. Staccato lightning (multiply branched, single stroke flash with no continuing current) is prevalent within the rainfree region around the main storm updraft and this is believed to be important, i.e., staccato flashes might be an important indicator of severe storm electrification. Results from data analysis from two stations appear to indicate that charge center heights can be estimated from a combination of intercept data with data from the fixed laboratory at NSSL. An excellent data base has been provided for determining the sight errors and efficiency of NSSL's LLP system. Cloud structures, observable in a low radar reflectivity region and on a scale smaller than is currently resolved by radar, which appear to be related to electrical activity are studied.

  3. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Rust, W. D.; Macgorman, D. R.; Taylor, W.; Arnold, R. T.

    1984-01-01

    Severe storms and lightning were measured with a NASA U2 and ground based facilities, both fixed base and mobile. Aspects of this program are reported. The following results are presented: (1) ground truth measurements of lightning for comparison with those obtained by the U2. These measurements include flash type identification, electric field changes, optical waveforms, and ground strike location; (2) simultaneous extremely low frequency (ELF) waveforms for cloud to ground (CG) flashes; (3) the CG strike location system (LLP) using a combination of mobile laboratory and television video data are assessed; (4) continued development of analog-to-digital conversion techniques for processing lightning data from the U2, mobile laboratory, and NSSL sensors; (5) completion of an all azimuth TV system for CG ground truth; (6) a preliminary analysis of both IC and CG lightning in a mesocyclone; and (7) the finding of a bimodal peak in altitude lightning activity in some storms in the Great Plains and on the east coast. In the forms on the Great Plains, there was a distinct class of flash what forms the upper mode of the distribution. These flashes are smaller horizontal extent, but occur more frequently than flashes in the lower mode of the distribution.

  4. Electrical storm: Incidence, Prognosis and Therapy

    PubMed Central

    Proietti, Riccardo; Sagone, Antonio

    2011-01-01

    Implantable defibrillators are lifesavers and have improved mortality rates in patients at risk of sudden death, both in primary and secondary prevention. However, they are unable to modify the myocardial substrate, which remains susceptible to life-threatening ventricular arrhythmias. Electrical storm is a clinical entity characterized the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, twice or more in 24 hours, requiring electrical cardioversion or defibrillation. With the arrival of the implantable cardioverter-defibrillator, this definition was broadened, and electrical storm is now defined as the occurrence of three or more distinct episodes of ventricular tachycardia or ventricular fibrillation in 24 hours, requiring the intervention of the defibrillator (anti-tachycardia pacing or shock). Clinical presentation can be very dramatic, with multiple defibrillator shocks and hemodynamic instability. Managing its acute presentation is a challenge, and mortality is high both in the acute phase and in the long term. In large clinical trials involving patients implanted with a defibrillator both for primary and secondary prevention, electrical storm appears to be a harbinger of cardiac death, with notably high mortality soon after the event. In most cases, the storm can be interrupted by medical therapy, though transcatheter radiofrequency ablation of ventricular arrhythmias may be an effective treatment for refractory cases. This narrative literature review outlines the main clinical characteristics of electrical storm and emphasises critical points in approaching and managing this peculiar clinical entity. Finally focus is given to studies that consider transcatheter ablation therapy in cases refractory to medical treatment. PMID:21468247

  5. Electrical Storm: Incidence, Prognosis and Therapy.

    PubMed

    Sagone, Antonio

    2015-12-01

    The term "electrical storm" indicates a life-threatening clinical condition characterized by the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, in particular in patients with ICD implanted for primary or secondary prevention. Although there isn't a shared definition of electrical storm, nowadays the most accepted definition refers to three or more separate arrhythmia episodes leading to ICD therapies including antitachycardia pacing or shock occurring over a single 24 hours' time period. Clinical presentation can be dramatic and triggering mechanism are not clear at all yet, but electrical storm is associated with high mortality rates and low patients quality of life, both in the acute phase and in the long term. The first line therapy is based on antiarrhythmic drugs to suppress electrical storm, but in refractory patients, interventions such as catheter ablation or in some cases surgical cardiac sympathetic denervation might be helpful. Anyhow, earlier interventional management can lead to better outcomes than persisting with antiarrhythmic pharmacologic therapy and, when available, an early interventional approach should be preferred.

  6. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Rust, W. D.; Macgorman, D. R.

    1985-01-01

    During FY-85, Researchers conducted a field program and analyzed data. The field program incorporated coordinated measurements made with a NASA U2. Results include the following: (1) ground truth measurements of lightning for comparison with those obtained by the U2; (2) analysis of dual-Doppler radar and dual-VHF lightning mapping data from a supercell storm; (3) analysis of synoptic conditions during three simultaneous storm systems on 13 May 1983 when unusually large numbers of positive cloud-to-ground (+CG) flashes occurred; (4) analysis of extremely low frequency (ELF) wave forms; and (5) an assessment of a cloud -ground strike location system using a combination of mobile laboratory and fixed-base TV video data.

  7. Synergistic application of cardiac sympathetic decentralization and comprehensive psychiatric treatment in the management of anxiety and electrical storm

    PubMed Central

    Khalsa, Sahib S.; Shahabi, Leila; Ajijola, Olujimi A.; Bystritsky, Alexander; Naliboff, Bruce D.; Shivkumar, Kalyanam

    2014-01-01

    We report here, for the first time, two cases demonstrating a synergistic application of bilateral cardiac sympathetic decentralization and multimodal psychiatric treatment for the assessment and management of anxiety following recurrent Implantable Cardioverter Defibrillator (ICD) shocks. In a first case the combination of bilateral cardiac sympathetic decentralization (BCSD), cognitive behavioral psychotherapy and anxiolytic medication was sufficient to attenuate the patient's symptoms and maladaptive behaviors, with a maintained benefit at 1 year. Among the more prominent subjective changes in the post-lesion state we observed a decrease in aversive interoceptive sensations, particularly of the heartbeat. The patient continued to experience cognitive threat appraisals on a frequent basis, although these were no longer incapacitating. In a second case, we report the effect of BCSD on autonomic tone and subjective state. In the post-lesion state we observed attenuated sympathetic responses to the valsalva maneuver, isometric handgrip and mental arithmetic stressor, including decreased systolic and diastolic blood pressure and, decreased skin conductance. Collectively, these preliminary findings suggest that an integrative, multidisciplinary approach to treating anxiety disorders in the setting of ventricular arrhythmias and recurrent ICD shocks can result in sustained improvements in physical, psychological, and functional status. These findings raise the possibility of a potential role for the stellate ganglion in the modulation of emotional experience and afferent transmission of interoceptive information to the central nervous system. PMID:24427121

  8. A study of severe storm electricity via storm intercept

    NASA Technical Reports Server (NTRS)

    Arnold, Roy T.; Horsburgh, Steven D.; Rust, W. David; Burgess, Don

    1985-01-01

    Storm electricity data, radar data, and visual observations were used both to present a case study for a supercell thunderstorm that occurred in the Texas Panhandle on 19 June 1980 and to search for insight into how lightning to ground might be related to storm dynamics in the updraft/downdraft couplet in supercell storms. It was observed that two-thirds of the lightning ground-strike points in the developing and maturing stages of a supercell thunderstorm occurred within the region surrounding the wall cloud (a cloud feature often characteristic of a supercell updraft) and on the southern flank of the precipitation. Electrical activity in the 19 June 1980 storm was atypical in that it was a right-mover. Lightning to ground reached a peak rate of 18/min and intracloud flashes were as frequent as 176/min in the final stages of the storm's life.

  9. The evaluation and management of electrical storm.

    PubMed

    Eifling, Michael; Razavi, Mehdi; Massumi, Ali

    2011-01-01

    Electrical storm is an increasingly common and life-threatening syndrome that is defined by 3 or more sustained episodes of ventricular tachycardia, ventricular fibrillation, or appropriate shocks from an implantable cardioverter-defibrillator within 24 hours. The clinical presentation can be dramatic. Electrical storm can manifest itself during acute myocardial infarction and in patients who have structural heart disease, an implantable cardioverter-defibrillator, or an inherited arrhythmic syndrome. The presence or absence of structural heart disease and the electrocardiographic morphology of the presenting arrhythmia can provide important diagnostic clues into the mechanism of electrical storm. Electrical storm typically has a poor outcome.The effective management of electrical storm requires an understanding of arrhythmia mechanisms, therapeutic options, device programming, and indications for radiofrequency catheter ablation. Initial management involves determining and correcting the underlying ischemia, electrolyte imbalances, or other causative factors. Amiodarone and β-blockers, especially propranolol, effectively resolve arrhythmias in most patients. Nonpharmacologic treatment, including radiofrequency ablation, can control electrical storm in drug-refractory patients. Patients who have implantable cardioverter-defibrillators can present with multiple shocks and may require drug therapy and device reprogramming. After the acute phase of electrical storm, the treatment focus should shift toward maximizing heart-failure therapy, performing revascularization, and preventing subsequent ventricular arrhythmias. Herein, we present an organized approach for effectively evaluating and managing electrical storm.

  10. Cervical sympathetic blockade for the management of electrical storm.

    PubMed

    Ali, Rehan; Ciccone, Jeffrey; Tseng, Victor

    2017-02-01

    A 75-year-old man presented with dizziness and fatigue secondary to ventricular and supraventricular arrhythmias. He underwent an elective ablation but continued to suffer from ventricular tachycardia with cardiovascular instability despite antiarrhythmic therapy with multiple agents. The patient continued to develop episodes of ventricular tachycardia and an episode of ventricular fibrillation. Electrical storm encompasses a situation of cardiac instability which may present as several episodes of ventricular tachycardia or ventricular fibrillation in a short period. We performed an ultrasound-guided left stellate ganglion block at the bedside which resulted in abolition of electrical storm. The patient demonstrated sinus rhythm with episodes of sinus tachycardia. Left stellate ganglion block has proven to be a successful mode of treatment for those patients with ventricular tachyarrhythmia resistant to medical management or those who fail atrioventricular node ablation. Ultrasound-guided left stellate ganglion block is a valuable and effective means to providing sympathectomy in the management of electrical storm or ventricular tachyarrhythmias.

  11. Left ventricular assist device in the management of refractory electrical storm.

    PubMed

    Pourdjabbar, A; Maze, R; Hibbert, B; Ruel, M; Haddad, H

    2015-05-01

    Electrical storm refers to a state of cardiac electrical instability characterized by multiple episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) within a relatively short period of time and is associated with increased mortality and morbidity. The management of electrical storm involves a variety of strategies, including sedation, anti-arrhythmic and electrolyte replacement as well as revascularization and electrical ablation. However, the management strategy in patients with refractory storm is less clear and may require more invasive approaches. We present a case of severe ventricular tachycardia storm refractory to conservative management that was managed with a HeartMate II left ventricular assist device.

  12. Electrical storm: A clinical and electrophysiological overview

    PubMed Central

    Conti, Sergio; Pala, Salvatore; Biagioli, Viviana; Del Giorno, Giuseppe; Zucchetti, Martina; Russo, Eleonora; Marino, Vittoria; Dello Russo, Antonio; Casella, Michela; Pizzamiglio, Francesca; Catto, Valentina; Tondo, Claudio; Carbucicchio, Corrado

    2015-01-01

    Electrical storm (ES) is a clinical condition characterized by three or more ventricular arrhythmia episodes leading to appropriate implantable cardioverter-defibrillator (ICD) therapies in a 24 h period. Mostly, arrhythmias responsible of ES are multiple morphologies of monomorphic ventricular tachycardia (VT), but polymorphic VT and ventricular fibrillation can also result in ES. Clinical presentation is very dramatic in most cases, strictly related to the cardiac disease that may worsen electrical and hemodynamic decompensation. Therefore ES management is challenging in the majority of cases and a high mortality is the rule both in the acute and in the long-term phases. Different underlying cardiomyopathies provide significant clues into the mechanism of ES, which can arise in the setting of structural arrhythmogenic cardiomyopathies or rarely in patients with inherited arrhythmic syndrome, impacting on pharmacological treatment, on ICD programming, and on the opportunity to apply strategies of catheter ablation. This latter has become a pivotal form of treatment due to its high efficacy in modifying the arrhythmogenic substrate and in achieving rhythm stability, aiming at reducing recurrences of ventricular arrhythmia and at improving overall survival. In this review, the most relevant epidemiological and clinical aspects of ES, with regard to the acute and long-term follow-up implications, were evaluated, focusing on these novel therapeutic strategies of treatment. PMID:26413232

  13. Optimal antiarrhythmic drug therapy for electrical storm

    PubMed Central

    Sorajja, Dan; Munger, Thomas M.; Shen, Win-Kuang

    2015-01-01

    Abstract Electrical storm, defined as 3 or more separate episodes of ventricular tachycardia or ventricular fibrillation within 24 hours, carries significant morbidity and mortality. These unstable ventricular arrhythmias have been described with a variety of conditions including ischemic heart disease, structural heart disease, and genetic conditions. While implantable cardioverter defibrillator implantation and ablation may be indicated and required, antiarrhythmic medication remains an important adjunctive therapy for these persons. PMID:25745472

  14. Electrical Activity in Martian Dust Storms

    NASA Astrophysics Data System (ADS)

    Majid, W.

    2015-12-01

    Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges, even larger than those in dust storms on Earth. Such electrical activity poses serious risks to any Human exploration of the planet and the lack of sufficient data to characterize any such activity has been identified by NASA's MEPAG as a key human safety knowledge gap. There are three key elements in the characterization of Martian electrostatic discharges: dependence on Martian environmental conditions, frequency of occurrence, and the strength of the generated electric fields. We will describe a proposed program using NASA's Deep Space Network (DSN) to carry out a long term monitoring campaign to search for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of spacecraft at Mars on an entirely non-interfering basis. The resulting knowledge of Mars electrical activity would allow NASA to plan risk mitigation measures to ensure human safety during Mars exploration. In addition, these measurements will also allow us to place limits on presence of oxidants such as H2O2 that may be produced by such discharges, providing another measurement point for models describing Martian atmospheric chemistry and habitability. Because of the continuous Mars telecommunication needs of NASA's Mars-based assets, the DSN is the only instrument in the world that combines long term, high cadence, observing opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and characterizing electrostatic activity at Mars from the ground.

  15. Reducing uncertainty - responses for electricity utilities to severe solar storms

    NASA Astrophysics Data System (ADS)

    Gaunt, Charles Trevor

    2014-01-01

    Until recently, electricity utilities in mid- and low-latitude regions believed that solar storms had no (or only insignificant) effect on their power systems. Then it was noticed that the onset of damage in several large transformers, leading to their failure, correlated very closely with the Halloween storm of 2003. Since then engineers have started to appreciate that a very severe storm could have serious consequences outside the high-latitude regions. There are many uncertainties in predicting the effects of solar storms on electrical systems. The severity and time of arrival of a storm are difficult to model; so are the geomagnetically induced currents (GICs) expected to flow in the power networks. Published information about the responses of different types of transformers to GICs is contradictory. Measurements of the abnormal power flows in networks during solar storms generally do not take into account the effects of the current distortion and unbalance, potentially giving misleading signals to the operators. The normal requirement for optimum system management, while allowing for the possibility of faults caused by lightning, birds and other causes, limits the capacity of system operators to respond to the threats of GICs, which are not assessed easily by the N - 1 reliability criterion. A utility's response to the threat of damage by GICs depends on the expected frequency and magnitude of solar storms. Approaches to formulating a response are located in a system model incorporating space physics, network analysis, transformer engineering, network reliability and decision support and the benefits are identified. Approaches adopted in high-latitude regions might not be appropriate where fewer storms are expected to reach damaging levels. The risks of an extreme storm cannot be ignored, and understanding the response mechanisms suitable for low-latitude regions has the capacity to inform and reduce the uncertainty for power systems planners and operators

  16. Historically Large Geomagnetic Storms and Potential Electric Power Grid Impacts

    NASA Astrophysics Data System (ADS)

    Kappenman, J. G.

    2004-05-01

    While recent work has been done to examine the possible Dst Intensity of historically large geomagnetic storms, the impacts caused to modern day electric power grids from these storms occurs due to rapid rate-of-change of regional geomagnetic fields which in most cases are driven by large ionospheric electrojet current intensifications. These temporally and spatially dynamic disturbance morphologies are not well-characterized by Dst or other broad geomagnetic storm indices. For estimates of storm intensity that correctly scale the threat potential to electric power grids, it is necessary to describe the rate-of-change of geomagnetic field. The rate-of-change of the geomagnetic field (dB/dt usually measured in nT/min) creates at ground level a geoelectric field that causes the flow of geomagnetically-induced currents (GIC) through ground connection points in electric power grids. Therefore in general, the larger the dB/dt, the larger the resulting geo-electric field and GIC in exposed power grid infrastructures and the greater the operational impact these induced currents will have on the power grid. Both extensive modeling analysis and recent operational experience suggests that power grids are becoming more vulnerable to geomagnetic storms as they grow in size and complexity. Also, large power grid blackouts have occurred at relatively low geomagnetic storm intensities. For example, the regional disturbance intensity that triggered the Hydro Quebec collapse during the March 13, 1989 Superstorm only reached an intensity of 479 nT/min. Large numbers of power system impacts in the United States were also observed for intensities that ranged from 300 to 600 nT/min during this storm. Yet both recent and historical data indicate that storms with disturbance levels that range from 2000 nT/min to as much ~5000 nT/min may be possible over extensive regions at latitudes of concern for large continental power grids across North America and Europe. Large GIC have also been

  17. Exploratory Meeting on Atmospheric Electricity and Severe Storms

    NASA Technical Reports Server (NTRS)

    Vaughan, W. W. (Editor)

    1978-01-01

    The meeting was arranged to discuss atmospheric electricity and its relationship to severe storms, the feasibility of developing a set of instruments for either a Space Shuttle or an unmanned satellite, and the scientific rationale which would warrant further in-depth assessment, involvement and development of supporting activities by NASA.

  18. Electrical stimulation systems for cardiac tissue engineering.

    PubMed

    Tandon, Nina; Cannizzaro, Christopher; Chao, Pen-Hsiu Grace; Maidhof, Robert; Marsano, Anna; Au, Hoi Ting Heidi; Radisic, Milica; Vunjak-Novakovic, Gordana

    2009-01-01

    We describe a protocol for tissue engineering of synchronously contractile cardiac constructs by culturing cardiac cells with the application of pulsatile electrical fields designed to mimic those present in the native heart. Tissue culture is conducted in a customized chamber built to allow for cultivation of (i) engineered three-dimensional (3D) cardiac tissue constructs, (ii) cell monolayers on flat substrates or (iii) cells on patterned substrates. This also allows for analysis of the individual and interactive effects of pulsatile electrical field stimulation and substrate topography on cell differentiation and assembly. The protocol is designed to allow for delivery of predictable electrical field stimuli to cells, monitoring environmental parameters, and assessment of cell and tissue responses. The duration of the protocol is 5 d for two-dimensional cultures and 10 d for 3D cultures.

  19. Electrical stimulation systems for cardiac tissue engineering

    PubMed Central

    Tandon, Nina; Cannizzaro, Christopher; Chao, Pen-Hsiu Grace; Maidhof, Robert; Marsano, Anna; Au, Hoi Ting Heidi; Radisic, Milica; Vunjak-Novakovic, Gordana

    2009-01-01

    We describe a protocol for tissue engineering of synchronously contractile cardiac constructs by culturing cardiac cells with the application of pulsatile electrical fields designed to mimic those present in the native heart. Tissue culture is conducted in a customized chamber built to allow for cultivation of (i) engineered three-dimensional (3D) cardiac tissue constructs, (ii) cell monolayers on flat substrates or (iii) cells on patterned substrates. This also allows for analysis of the individual and interactive effects of pulsatile electrical field stimulation and substrate topography on cell differentiation and assembly. The protocol is designed to allow for delivery of predictable electrical field stimuli to cells, monitoring environmental parameters, and assessment of cell and tissue responses. The duration of the protocol is 5 d for two-dimensional cultures and 10 d for 3D cultures. PMID:19180087

  20. Surface electric fields for North America during historical geomagnetic storms

    USGS Publications Warehouse

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  1. Surface electric fields for North America during historical geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Wei, Lisa H.; Homeier, Nicole; Gannon, Jennifer L.

    2013-08-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  2. TRPM4 in cardiac electrical activity.

    PubMed

    Guinamard, Romain; Bouvagnet, Patrice; Hof, Thomas; Liu, Hui; Simard, Christophe; Sallé, Laurent

    2015-10-01

    TRPM4 forms a non-selective cation channel activated by internal Ca(2+). Its functional expression was demonstrated in cardiomyocytes of several mammalian species including humans, but the channel is also present in many other tissues. The recent characterization of the TRPM4 inhibitor 9-phenanthrol, and the availability of transgenic mice have helped to clarify the role of TRPM4 in cardiac electrical activity, including diastolic depolarization from the sino-atrial node cells in mouse, rat, and rabbit, as well as action potential duration in mouse cardiomyocytes. In rat and mouse, pharmacological inhibition of TRPM4 prevents cardiac ischaemia-reperfusion injuries and decreases the occurrence of arrhythmias. Several studies have identified TRPM4 mutations in patients with inherited cardiac diseases including conduction blocks and Brugada syndrome. This review identifies TRPM4 as a significant actor in cardiac electrophysiology.

  3. Complicated Electrical Activities in Cardiac Tissue

    NASA Astrophysics Data System (ADS)

    Shiau, Yuo-Hsien; Hsueh, Ming-Pin; Hseu, Shu-Shya; Yien, Huey-Wen

    It has become widely accepted that ventricular fibrillation, the most dangerous cardiac arrhythmias, is a major cause of death in the industrialized world. Alternans and conduction block have recently been related to the progression from ventricular tachycardia to ventricular fibrillation. From the point of view in cellular electrophysiology, ventricular tachycardia is the formation of reentrant wave in cardiac tissue. And ventricular fibrillation arises from subsequent breakdown of reentrant wave into multiple drifting and meandering spiral waves. In this paper, we numerically study pulse and vortex dynamics in cardiac tissue. Our numerical results include 1:1 normal sinus rhythm, 2:1 conduction block, complete conduction block, spiral wave, and spiral breakup. All of our numerical findings can be corresponding to clinical measurements in electrocardiogram. Various electrical activities in cardiac tissue will be discussed in detail in the present manuscript.

  4. Imaging of cardiac electrical excitation conduction.

    PubMed

    Zhou, D F; Jiang, S Q; Zhu, J C; Zhao, C; Yan, Y R; Gronemeyer, D; Van Leeuwen, P

    2015-08-01

    We present a multiple time windows beamformer (MTWB) method of solving the inverse problem of magnetic field and non-invasively imaging the cardiac electrical excitation conduction using the magnetocardiac signals acquired by a 61-channel superconducting quantum interference device (SQUID). The MTWB constructs spatial filters for each location in source space, one for each component of the source moment based on the distributed source model, and estimates the cardiac equivalent current sources. The output of spatial filters is the source strength estimated in three-dimensional space and the weight matrix calculated with magnetocardiac signals in multiple time windows. A signal subspace projection technique is used to suppress noise. Then, the characteristics of cardiac electrical excitation conduction among two healthy subjects and two coronary vessel stenosis (CVS) patients are extracted from reconstructed current sources with maximum strength at each instant during QRS complex and ST-T segment, and a series of two-dimensional cardiac electrical excitation conduction maps (EECM) are obtained. It is demonstrated that two healthy subjects are of similar and the stronger electrical activities than those of two CVS patients. This technique can be used as an effective tool for the diagnosis of heart diseases.

  5. Polarimetric Radar and Electric Field Observations of a Multicell Storm

    NASA Astrophysics Data System (ADS)

    Bruning, E. C.; Rust, W. D.; Macgorman, D. R.; Schuur, T.; Straka, J.; Krehbiel, P.; Rison, W.

    2004-12-01

    Much prior thunderstorm electrification research uses one-dimensional analyses of vertical profiles of the thunderstorm electric field, often incorporating cloud-to-ground lighting strike data and radar reflectivity observations. New instrumentation has provided the opportunity to investigate thunderstorm electrification and lightning in greater spatial detail. We present data from the late stages of a multicellular storm occurring on 28-29 June 2004 during the Thunderstorm Electrification and Lightning Experiment (TELEX) field program in central Oklahoma. Three-dimensional (3-D) vector electric field (measured by balloon sounding), total lighting mapping, and polarimetric radar are utilized. The maximum measured electric field exceeded -150 kV m-1. Preliminary charge analysis using the electric field vectors indicates a positive layer below 0\\deg C, followed by a large negative layer just above the melting level. Another positive and negative layer follow this. Polarimetric radar signatures within the melting layer are examined in the context of the electric field observations. Mapped lightning flashes are used to clarify and support the inferred charge structure. An interactive 3-D display is used to combine these data sources. Temporal evolution of the storm is also considered.

  6. Electrical Discharges in the Overshooting Tops of Five Storms

    NASA Astrophysics Data System (ADS)

    MacGorman, D. R.; Elliott, M.

    2013-12-01

    Individual electrical discharges detected by VHF Lightning Mapping Arrays (LMAs) in the overshooting tops of strong storms typically occur continually at rates of roughly 1 - 10 per second and do not appear to cluster systematically in time or space as flashes. This study analyzed discharges relative to S-band polarimetric radar data and to GOES infrared imagery in the overshooting tops of five storms ranging from moderately strong multicell storms to supercell storms. Although the density of VHF sources in overshooting tops was much less than the maximum densities below the level of neutral bouyancy, the overshooting top typically contained a secondary maximum of density. The onset of discharges in an overshooting top corresponded to an increase in the maximum magnitude and height of reflectivity as the top substantially penetrated the level of neutral bouyancy. Once the discharges began, most were within reflectivities of at least 18 dBZ and formed a dome having geometry similar to that of the dome in reflectivity. Discharges persisted for approximately as long as the reflectivity dome persisted and could last anywhere from a few minutes for short-lived overshooting tops to a few hours for cases with an overlapping series of overshooting tops produced by a succession of updraft pulses. The 99.99th percentile in the height of VHF sources was well correlated (correlation coefficient of at least 0.8) with the height of 18 and 30 dBZ, and the timing of variations in height of these parameters agreed well. We suggest the discharges are caused by turbulent cells bringing negative screening layer charge close to positive charge in the updraft core. The onset of discharges in an overshooting top preceded the detection of overshooting tops in satellite imagery. The poorer performance probably was the result of the poorer spatiotemporal resolution of infrared cloud-top imagery in the present GOES constellation. Severe weather was either imminent or occurring when

  7. Atmospheric Electricity Effects of Eastern Mediterranean Dust Storms

    NASA Astrophysics Data System (ADS)

    Katz, Shai; Yair, Yoav; Yaniv, Roy; Price, Colin

    2016-04-01

    We present atmospheric electrical measurements conducted at the Wise Observatory (WO) in Mizpe-Ramon (30035'N, 34045'E) and Mt. Hermon (30024'N, 35051'E), Israel, during two massive and unique dust storms that occurred over the Eastern Mediterranean region on February 10-11 and September 08-12, 2015. The first event transported Saharan dust from Egypt and the Sinai Peninsula in advance of a warm front of a Cyprus low pressure system. In the second event, dust particles were transported from the Syrian desert, which dominates the north-east border with Iraq, through flow associated with a shallow Persian trough system. In both events the concentrations of PM10 particles measured by the air-quality monitoring network of the Israeli Ministry of the Environment in Beer-Sheba reached values > 2200 μg m-3. Aerosol Optical Thickness (AOT) obtained from the AERONET station in Sde-Boker reached values up to 4.0. The gradual intensification of the first event reached peak values on the February 11th > 1200 μg m-3 and an AOT ~ 1.8, while the second dust storm commenced on September 8th with a sharp increase reaching peak values of 2225 μg m-3 and AOT of 4.0. Measurements of the fair weather vertical electric field (Ez) and of the vertical current density (Jz) were conducted continuously with a 1 minute temporal resolution. During the February event, very large fluctuations in the electrical parameters were measured at the WO. The Ez values changed between +1000 and +8000 V m-1 while the Jz fluctuated between -10 and +20 pA m-2 (this is an order of magnitude larger compared to the fair weather current density of ~2 pA m-2. In contrast, during the September event, Ez values registered at WO were between -430 and +10 V m-1 while the Jz fluctuated between -6 and +3 pA m2. For the September event the Hermon site showed Ez and Jz values fluctuating between -460 and +570 V m-1 and -14.5 and +18 pA m-2 respectively. The electric field and current variability, amplitude and the

  8. Brain responses to cardiac electrical stimulation: a new EEG method for evaluating cardiac sensation.

    PubMed

    Suzuki, Hideaki; Hirose, Masanori; Watanabe, Satoshi; Fukuda, Koji; Fukudo, Shin; Shimokawa, Hiroaki

    2012-01-01

    Although cardiac sensation, such as palpitation or chest pain, is common and is sometimes a malignant sign of heart diseases, the mechanism by which the human brain responds to afferent signals from the heart remains unclear. In this study, we investigated whether electrical stimulation of the heart provokes brain responses in humans. We examined 15 patients (age: 65.4 ± 3.1 years old, 11 males and 4 females) implanted with either a cardiac pacemaker or cardiac resynchronization therapy (CRT) device. Electroencephalogram (EEG) was simultaneously recorded from the vertex during right ventricular pacing at 70-100 beats/min at baseline (1.5 V) and intense (6-8 V) stimulation sessions. We evaluated brain responses to cardiac electrical stimulation by measuring cerebral potentials that were obtained by subtracting the average of 100 EEG waves triggered by cardiac pacing during baseline stimulation from those during the intense stimulation. Intense stimulation of the cardiac pacemaker or CRT device reproducibly induced cardiac sensation in 6 out of the 15 patients; namely, the remaining 9 patients showed no reproducible response. Brain responses were evident by averaging cerebral potentials from all of the 15 patients and those from 6 patients with reproducible cardiac sensation. To the best our knowledge, this is the first report that demonstrates the brain responses to cardiac electrical stimulation in humans. This new method should be useful for examining pathophysiology of cardiac diseases with pathological cardiac sensation, including cardiac anxiety and silent myocardial ischemia.

  9. Optimization of electrical stimulation parameters for cardiac tissue engineering.

    PubMed

    Tandon, Nina; Marsano, Anna; Maidhof, Robert; Wan, Leo; Park, Hyoungshin; Vunjak-Novakovic, Gordana

    2011-06-01

    In vitro application of pulsatile electrical stimulation to neonatal rat cardiomyocytes cultured on polymer scaffolds has been shown to improve the functional assembly of cells into contractile engineered cardiac tissues. However, to date, the conditions of electrical stimulation have not been optimized. We have systematically varied the electrode material, amplitude and frequency of stimulation to determine the conditions that are optimal for cardiac tissue engineering. Carbon electrodes, exhibiting the highest charge-injection capacity and producing cardiac tissues with the best structural and contractile properties, were thus used in tissue engineering studies. Engineered cardiac tissues stimulated at 3 V/cm amplitude and 3 Hz frequency had the highest tissue density, the highest concentrations of cardiac troponin-I and connexin-43 and the best-developed contractile behaviour. These findings contribute to defining bioreactor design specifications and electrical stimulation regime for cardiac tissue engineering.

  10. Optimization of Electrical Stimulation Parameters for Cardiac Tissue Engineering

    PubMed Central

    Tandon, Nina; Marsano, Anna; Maidhof, Robert; Wan, Leo; Park, Hyoungshin; Vunjak-Novakovic, Gordana

    2010-01-01

    In vitro application of pulsatile electrical stimulation to neonatal rat cardiomyocytes cultured on polymer scaffolds has been shown to improve the functional assembly of cells into contractile cardiac tissue constrcuts. However, to date, the conditions of electrical stimulation have not been optimized. We have systematically varied the electrode material, amplitude and frequency of stimulation, to determine the conditions that are optimal for cardiac tissue engineering. Carbon electrodes, exhibiting the highest charge-injection capacity and producing cardiac tissues with the best structural and contractile properties, and were thus used in tissue engineering studies. Cardiac tissues stimulated at 3V/cm amplitude and 3Hz frequency had the highest tissue density, the highest concentrations of cardiac troponin-I and connexin-43, and the best developed contractile behavior. These findings contribute to defining bioreactor design specifications and electrical stimulation regime for cardiac tissue engineering. PMID:21604379

  11. Combined Aircraft and Satellite-Derived Storm Electric Current and Lightning Rates Measurements and Implications for the Global Electric Circuit

    NASA Technical Reports Server (NTRS)

    Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

    2010-01-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of electrified shower clouds and thunderstorms spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, with and without lightning, and with positive and negative fields above the storms. The measurements were made with the NASA ER-2 and the Altus-II high altitude aircrafts. Peak electric fields, with lightning transients removed, ranged from -1.0 kV/m to 16 kV/m, with a mean value of 0.9 kV/m. The median peak field was 0.29 kV/m. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean storms with lightning is 1.6 A while the mean current for land storms with lightning is 1.0 A. The mean current for oceanic storms without lightning (i.e., electrified shower clouds) is 0.39 A and the mean current for land storms without lightning is 0.13 A. Thus, on average, land storms with or without lightning have about half the mean current as their corresponding oceanic storm counterparts. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal lightning statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie

  12. Electrical Storm Simulation to Improve the Learning Physics Process

    ERIC Educational Resources Information Center

    Martínez Muñoz, Miriam; Jiménez Rodríguez, María Lourdes; Gutiérrez de Mesa, José Antonio

    2013-01-01

    This work is part of a research project whose main objective is to understand the impact that the use of Information and Communication Technology (ICT) has on the teaching and learning process on the subject of Physics. We will show that, with the use of a storm simulator, physics students improve their learning process on one hand they understand…

  13. Progress in utilization of a mobile laboratory for making storm electricity measurements

    NASA Technical Reports Server (NTRS)

    Rust, W. David

    1988-01-01

    A mobile atmospheric science laboratory has been used to intercept and track storms on the Great Plains region of the U.S., with the intention of combining the data obtained with those from Doppler and conventional radars, NASA U-2 aircraft overflights, balloon soundings, and fixed-base storm electricity measurements. The mobile lab has proven to be valuable in the gathering of ground truth verifications for the two commercially operated lightning ground-strike locating systems. Data acquisition has recently been expanded by means of mobile ballooning before and during storms.

  14. Evaluation of the electrical properties of dust storms by multi-parameter observations and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Zhang, Huan; Bo, Tian-Li; Zheng, Xiaojing

    2017-03-01

    Dusty phenomena, such as wind-blown sand, dust devils, and dust storms, play key roles in Earth's climate and geological processes. Dust electrification considerably affects the lifting and transport of dust particles. However, the electrical properties of dust storms remain poorly understood. Here, we conducted multi-parameter measurements and theoretical calculations to investigate the electrical properties of dust storms and their application to dust storm prediction. The results show that the vertical electric field (E-field) decreases first, then increases, and finally decreases with the height above the ground, reversing its direction at two heights, ∼ 8- 12 and ∼ 24 m. This suggests that the charge polarity of dust particles changes from negative to positive and back to negative again as the height increases. By carefully analyzing the E-field and dust concentration data, we further found that there is a significant positive linear relationship between the measured E-field intensity and dust concentration at the given ambient conditions. In addition, measurements and calculations demonstrate that a substantial enhancement in the vertical E-field can be observed several hours before the arrival of the external-source dust storms, indicating that the E-field can be used to provide an early warning of external-source dust storms.

  15. Automated Identification of Initial Storm Electrification and End-of-Storm Electrification Using Electric Field Mill Sensors

    NASA Technical Reports Server (NTRS)

    Maier, Launa M.; Huddleston, Lisa L.

    2017-01-01

    Kennedy Space Center (KSC) operations are located in a region which experiences one of the highest lightning densities across the United States. As a result, on average, KSC loses almost 30 minutes of operational availability each day for lightning sensitive activities. KSC is investigating using existing instrumentation and automated algorithms to improve the timeliness and accuracy of lightning warnings. Additionally, the automation routines will be warning on a grid to minimize under-warnings associated with not being located in the center of the warning area and over-warnings associated with encompassing too large an area. This study discusses utilization of electric field mill data to provide improved warning times. Specifically, this paper will demonstrate improved performance of an enveloping algorithm of the electric field mill data as compared with the electric field zero crossing to identify initial storm electrification. End-of-Storm-Oscillation (EOSO) identification algorithms will also be analyzed to identify performance improvement, if any, when compared with 30 minutes after the last lightning flash.

  16. Disturbance dynamo electric fields in response to geomagnetic storms occurring at different universal times

    NASA Astrophysics Data System (ADS)

    Huang, C.

    2013-12-01

    Perturbed electric fields in the earth's ionosphere, resulting from the penetration electric fields from high latitudes and/or from the dynamo mechanism driven by the neutral disturbances, occurr in the storm periods. In general, the identification of the penetration electric fields is easier than that of the dynamo electric fields. At times, the latter becomes unperceivable or difficult to identify. This is an interesting problem which motivates a model study to investigate the possible reasons. Model runs made with the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (NCAR/TIEGCM) will be presented. Theoretical studies of ionospheric responses to geomagnetic storms with model simulations indicate that the intensities of disturbance dynamo electric fields are highly dependent on various parameters such as solar activities, seasonal effects and universal times, etc. When geomagnetic storms commence at 01~07 UT in summer solstices with low solar fluxes, the disturbance dynamo electric fields become very small. As compared with the general daily variations, they seem to be unperceivable. This phenomenon can be explained by the model results which show that the positive charge accumulation at low latitudes will be weakened when the equatward neutral disturbances penetrate into the opposite hemisphere in the storm time. For other cases, the magnitudes of the dynamo electric fields are relatively larger under the same geomagnetic activity.

  17. Electrical and mechanical stimulation of cardiac cells and tissue constructs.

    PubMed

    Stoppel, Whitney L; Kaplan, David L; Black, Lauren D

    2016-01-15

    The field of cardiac tissue engineering has made significant strides over the last few decades, highlighted by the development of human cell derived constructs that have shown increasing functional maturity over time, particularly using bioreactor systems to stimulate the constructs. However, the functionality of these tissues is still unable to match that of native cardiac tissue and many of the stem-cell derived cardiomyocytes display an immature, fetal like phenotype. In this review, we seek to elucidate the biological underpinnings of both mechanical and electrical signaling, as identified via studies related to cardiac development and those related to an evaluation of cardiac disease progression. Next, we review the different types of bioreactors developed to individually deliver electrical and mechanical stimulation to cardiomyocytes in vitro in both two and three-dimensional tissue platforms. Reactors and culture conditions that promote functional cardiomyogenesis in vitro are also highlighted. We then cover the more recent work in the development of bioreactors that combine electrical and mechanical stimulation in order to mimic the complex signaling environment present in vivo. We conclude by offering our impressions on the important next steps for physiologically relevant mechanical and electrical stimulation of cardiac cells and engineered tissue in vitro.

  18. Design of electrical stimulation bioreactors for cardiac tissue engineering.

    PubMed

    Tandon, N; Marsano, A; Cannizzaro, C; Voldman, J; Vunjak-Novakovic, G

    2008-01-01

    Electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. Carbon electrodes were found in past studies to have the best current injection characteristics. The goal of this study was to develop rational experimental design principles for the electrodes and stimulation regime, in particular electrode configuration, electrode ageing, and stimulation amplitude. Carbon rod electrodes were compared via electrochemical impedance spectroscopy (EIS) and we identified a safety range of 0 to 8 V/cm by comparing excitation thresholds and maximum capture rates for neonatal rat cardiomyocytes cultured with electrical stimulation. We conclude with recommendations for studies involving carbon electrodes for cardiac tissue engineering.

  19. Design of Electrical Stimulation Bioreactors for Cardiac Tissue Engineering

    PubMed Central

    Tandon, N.; Marsano, A.; Cannizzaro, C.; Voldman, J.; Vunjak-Novakovic, G.

    2009-01-01

    Electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. Carbon electrodes were found in past studies to have the best current injection characteristics. The goal of this study was to develop rational experimental design principles for the electrodes and stimulation regime, in particular electrode configuration, electrode ageing, and stimulation amplitude. Carbon rod electrodes were compared via electrochemical impedance spectroscopy (EIS) and we identified a safety range of 0 to 8 V/cm by comparing excitation thresholds and maximum capture rates for neonatal rat cardiomyocytes cultured with electrical stimulation. We conclude with recommendations for studies involving carbon electrodes for cardiac tissue engineering. PMID:19163486

  20. External cardiac compression may be harmful in some scenarios of pulseless electrical activity.

    PubMed

    Hogan, T S

    2012-10-01

    Pulseless electrical activity occurs when organised or semi-organised electrical activity of the heart persists but the product of systemic vascular resistance and the increase in systemic arterial flow generated by the ejection of the left venticular stroke volume is not sufficient to produce a clinically detectable pulse. Pulseless electrical activity encompasses a very heterogeneous variety of severe circulatory shock states ranging in severity from pseudo-cardiac arrest to effective cardiac arrest. Outcomes of cardiopulmonary resuscitation for pulseless electrical activity are generally poor. Impairment of cardiac filling is the limiting factor to cardiac output in many scenarios of pulseless electrical activity, including extreme vasodilatory shock states. There is no evidence that external cardiac compression can increase cardiac output when impaired cardiac filling is the limiting factor to cardiac output. If impaired cardiac filling is the limiting factor to cardiac output and the heart is effectively ejecting all the blood returning to it, then external cardiac compression can only increase cardiac output if it increases venous return and cardiac filling. Repeated cardiac compression asynchronous with the patient's cardiac cycle and raised mean intrathoracic pressure due to chest compression can be expected to reduce rather than to increase cardiac filling and therefore to reduce rather than to increase cardiac output in such circumstances. The hypothesis is proposed that the performance of external cardiac compression will have zero or negative effect on cardiac output in pulseless electrical activity when impaired cardiac filling is the limiting factor to cardiac output. External cardiac compression may be both directly and indirectly harmful to significant sub-groups of patients with pulseless electrical activity. We have neither evidence nor theory to provide comfort that external cardiac compression is not harmful in many scenarios of pulseless

  1. Lightning Mapping and Electric Field Change Observations of a Stationary New Mexico Storm

    NASA Astrophysics Data System (ADS)

    Krehbiel, P. R.; Rison, W.; Hunyady, S. J.; Edens, H. E.; Sonnenfeld, R. G.; Aulich, G. D.

    2010-12-01

    On August 23, 2010 a classic airmass thunderstorm occurred over high plains immediately east of the Langmuir Laboratory mountaintop observatory in central New Mexico. The energetic storm developed around 2:30 pm MDT (2030 UTC) and remained essentially stationary over its complete lifetime of about 2 hours. The complete sequence of lightning was recorded both by the 16-station Langmuir Laboratory Lightning Mapping Array (LMA) and by several electrostatic field change stations around and beneath the storm. The LMA and Delta-E data are both of very high quality and sensitivity. In this initial study we report on the lightning-inferred electrical structure of the storm and on estimated charging currents determined from a simple electrodynamic model of the storm. The electric field change measurements, in combination with the detailed 3-D mapping results, can be used to determine the amounts of charge involved in individual strokes and parts of flashes for comparison and improvement of the modeling. The LMA data regularly detected isolated attempted breakdown events at repeated locations at mid- to high altitudes in the storm that were clearly indicative of localized high-field regions. The attempted breakdown events were often exact pre-cursors of the initial breakdown of full-fledged IC flashes typically several seconds up to several tens of seconds later, but also often did not precurse a subsequent discharge. During both IC and CG flashes, numerous recoil-type, fast negative breakdown events were detected along otherwise undetected positive leader channels in the main, mid-level negative charge region. The localized fast events during IC flashes often repeatedly intensified in strength and number prior to upward negative leader K-events, and then temporarily ceased before starting up again prior to the next K-event. Many of the negative CG flashes in the storm produced strokes with long continuing currents (CCs). The overall electric field changes and hence total

  2. A model of electrical conduction in cardiac tissue including fibroblasts.

    PubMed

    Sachse, Frank B; Moreno, A P; Seemann, G; Abildskov, J A

    2009-05-01

    Fibroblasts are abundant in cardiac tissue. Experimental studies suggested that fibroblasts are electrically coupled to myocytes and this coupling can impact cardiac electrophysiology. In this work, we present a novel approach for mathematical modeling of electrical conduction in cardiac tissue composed of myocytes, fibroblasts, and the extracellular space. The model is an extension of established cardiac bidomain models, which include a description of intra-myocyte and extracellular conductivities, currents and potentials in addition to transmembrane voltages of myocytes. Our extension added a description of fibroblasts, which are electrically coupled with each other and with myocytes. We applied the extended model in exemplary computational simulations of plane waves and conduction in a thin tissue slice assuming an isotropic conductivity of the intra-fibroblast domain. In simulations of plane waves, increased myocyte-fibroblast coupling and fibroblast-myocyte ratio reduced peak voltage and maximal upstroke velocity of myocytes as well as amplitudes and maximal downstroke velocity of extracellular potentials. Simulations with the thin tissue slice showed that inter-fibroblast coupling affected rather transversal than longitudinal conduction velocity. Our results suggest that fibroblast coupling becomes relevant for small intra-myocyte and/or large intra-fibroblast conductivity. In summary, the study demonstrated the feasibility of the extended bidomain model and supports the hypothesis that fibroblasts contribute to cardiac electrophysiology in various manners.

  3. Dayside midlatitude ionospheric response to storm time electric fields: A case study for 7 September 2002

    NASA Astrophysics Data System (ADS)

    David, M.; Sojka, J. J.; Schunk, R. W.; Liemohn, M. W.; Coster, A. J.

    2011-12-01

    With the storm of 7-8 September 2002 as a study case, we demonstrate that an ionospheric model driven by a suitable storm time convection electric field can reproduce the F region dayside density enhancements associated with the ionospheric storm positive phase. The ionospheric model in this case is the Utah State University Time Dependent Ionospheric Model (TDIM); the electric field model is the University of Michigan's Hot Electron and Ion Drift Integrator (HEIDI). Extensive ground truth is available throughout the study period from two independent sources: ground-based vertical TEC and ionosonde stations; our simulation results are in good agreement with these observations. We address the question of what is the source of the high-density plasma that is seen during the positive storm phase and show that in this case a magnetospheric electric field with an eastward component that penetrates to midlatitudes increases local production on the dayside to a degree that is sufficient to account for the storm time density increases that have been observed.

  4. Characterization of electrical stimulation electrodes for cardiac tissue engineering.

    PubMed

    Tandon, Nina; Cannizzaro, Chris; Figallo, Elisa; Voldman, Joel; Vunjak-Novakovic, Gordana

    2006-01-01

    Electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. The goal of this study was to assess the conditions of electrical stimulation with respect to the electrode geometry, material properties and charge-transfer characteristics at the electrode-electrolyte interface. We compared various biocompatible materials, including nanoporous carbon, stainless steel, titanium and titanium nitride, for use in cardiac tissue engineering bioreactors. The faradaic and non-faradaic charge transfer mechanisms were assessed by electrochemical impedance spectroscopy (EIS), studying current injection characteristics, and examining surface properties of electrodes with scanning electron microscopy. Carbon electrodes were found to have the best current injection characteristics. However, these electrodes require careful handling because of their limited mechanical strength. The efficacy of various electrodes for use in 2-D and 3-D cardiac tissue engineering systems with neonatal rat cardiomyocytes is being determined by assessing cell viability, amplitude of contractions, excitation thresholds, maximum capture rate, and tissue morphology.

  5. Integrative Modeling of Electrical Properties of Pacemaker Cardiac Cells

    NASA Astrophysics Data System (ADS)

    Grigoriev, M.; Babich, L.

    2016-06-01

    This work represents modeling of electrical properties of pacemaker (sinus) cardiac cells. Special attention is paid to electrical potential arising from transmembrane current of Na+, K+ and Ca2+ ions. This potential is calculated using the NaCaX model. In this respect, molar concentration of ions in the intercellular space which is calculated on the basis of the GENTEX model is essential. Combined use of two different models allows referring this approach to integrative modeling.

  6. Global Electric Circuit Diurnal Variation Derived from Storm Overflight and Satellite Optical Lightning Datasets

    NASA Technical Reports Server (NTRS)

    Mach, Douglas M.; Blakeslee, R. J.; Bateman, M. J.; Bailey, J. C.

    2011-01-01

    We have combined analyses of over 1000 high altitude aircraft observations of electrified clouds with diurnal lightning statistics from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) to produce an estimate of the diurnal variation in the global electric circuit. Using basic assumptions about the mean storm currents as a function of flash rate and location, and the global electric circuit, our estimate of the current in the global electric circuit matches the Carnegie curve diurnal variation to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Mean contributions to the global electric circuit from land and ocean thunderstorms are 1.1 kA (land) and 0.7 kA (ocean). Contributions to the global electric circuit from ESCs are 0.22 kA for ocean storms and 0.04 kA for land storms. Using our analysis, the mean total conduction current for the global electric circuit is 2.0 kA.

  7. Global Electric Circuit Implications of Combined Aircraft Storm Electric Current Measurements and Satellite-Based Diurnal Lightning Statistics

    NASA Technical Reports Server (NTRS)

    Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

    2011-01-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of thunderstorms and electrified shower clouds (ESCs) spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, and with positive and negative fields above the storms. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean thunderstorms is 1.7 A while the mean current for land thunderstorms is 1.0 A. The mean current for ocean ESCs 0.41 A and the mean current for land ESCs is 0.13 A. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal flash rate statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 1.1 kA (land) and 0.7 kA (ocean) from thunderstorms, and 0.22 kA (ocean) and 0.04 (land) from ESCs, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Mean storm counts are 1100 for land

  8. Global Electric Circuit Implications of Combined Aircraft Storm Electric Current Measurements and Satellite-Based Diurnal Lightning Statistics

    NASA Astrophysics Data System (ADS)

    Mach, D. M.; Blakeslee, R.; Bateman, M. G.

    2010-12-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of thunderstorms and electrified shower clouds (ESCs) spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, and with positive and negative fields above the storms. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean thunderstorms is 1.7 A while the mean current for land thunderstorms is 1.0 A. The mean current for ocean ESCs 0.41 A and the mean current for land ESCs is 0.13 A. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal flash rate statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 1.1 kA (land) and 0.7 kA (ocean) from thunderstorms, and 0.22 kA (ocean) and 0.04 (land) from ESCs, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Mean storm counts are 1100 for land

  9. Electrically Induced Calcium Handling in Cardiac Progenitor Cells

    PubMed Central

    Wagner, Mary B.

    2016-01-01

    For nearly a century, the heart was viewed as a terminally differentiated organ until the discovery of a resident population of cardiac stem cells known as cardiac progenitor cells (CPCs). It has been shown that the regenerative capacity of CPCs can be enhanced by ex vivo modification. Preconditioning CPCs could provide drastic improvements in cardiac structure and function; however, a systematic approach to determining a mechanistic basis for these modifications founded on the physiology of CPCs is lacking. We have identified a novel property of CPCs to respond to electrical stimulation by initiating intracellular Ca2+ oscillations. We used confocal microscopy and intracellular calcium imaging to determine the spatiotemporal properties of the Ca2+ signal and the key proteins involved in this process using pharmacological inhibition and confocal Ca2+ imaging. Our results provide valuable insights into mechanisms to enhance the therapeutic potential in stem cells and further our understanding of human CPC physiology. PMID:27818693

  10. In situ measurements and radar observations of a severe storm - Electricity, kinematics, and precipitation

    NASA Technical Reports Server (NTRS)

    Byrne, G. J.; Few, A. A.; Stewart, M. F.; Conrad, A. C.; Torczon, R. L.

    1987-01-01

    Electric field measurements made inside a multicell severe storm in Oklahoma in 1983 with a balloon-borne instrument are presented. The properties of the electric charge regions, such as altitude, thickness, and charge concentrations, are studied. These measurements are analzyed with meteorological measurements of temperature and humidity, and balloon tracking and radar observations. The relation between the electric charge structure and the precipitation and kinematic features of the storm is examined. The data reveal that the cell exhibits a bipolar charge structure with negative charge below positive charge. The average charge concentrations of the two regions are estimated as -1.2 and 0.15 nC/cu m, respectively; the upper positive charge is about 6 km in vertical extent, and the lower negative charge is less than 1 km in vertical extent.

  11. Model of electrical activity in cardiac tissue under electromagnetic induction.

    PubMed

    Wu, Fuqiang; Wang, Chunni; Xu, Ying; Ma, Jun

    2016-12-01

    Complex electrical activities in cardiac tissue can set up time-varying electromagnetic field. Magnetic flux is introduced into the Fitzhugh-Nagumo model to describe the effect of electromagnetic induction, and then memristor is used to realize the feedback of magnetic flux on the membrane potential in cardiac tissue. It is found that a spiral wave can be triggered and developed by setting specific initials in the media, that is to say, the media still support the survival of standing spiral waves under electromagnetic induction. Furthermore, electromagnetic radiation is considered on this model as external stimuli, it is found that spiral waves encounter breakup and turbulent electrical activities are observed, and it can give guidance to understand the occurrence of sudden heart disorder subjected to heavily electromagnetic radiation.

  12. Electricity Demand Evolution Driven by Storm Motivated Population Movement

    SciTech Connect

    Allen, Melissa R; Fernandez, Steven J; Fu, Joshua S; Walker, Kimberly A

    2014-01-01

    Managing the risks posed by climate change to energy production and delivery is a challenge for communities worldwide. Sea Level rise and increased frequency and intensity of natural disasters due to sea surface temperature rise force populations to move locations, resulting in changing patterns of demand for infrastructure services. Thus, Infrastructures will evolve to accommodate new load centers while some parts of the network are underused, and these changes will create emerging vulnerabilities. Combining climate predictions and agent based population movement models shows promise for exploring the universe of these future population distributions and changes in coastal infrastructure configurations. In this work, we created a prototype agent based population distribution model and developed a methodology to establish utility functions that provide insight about new infrastructure vulnerabilities that might result from these patterns. Combining climate and weather data, engineering algorithms and social theory, we use the new Department of Energy (DOE) Connected Infrastructure Dynamics Models (CIDM) to examine electricity demand response to increased temperatures, population relocation in response to extreme cyclonic events, consequent net population changes and new regional patterns in electricity demand. This work suggests that the importance of established evacuation routes that move large populations repeatedly through convergence points as an indicator may be under recognized.

  13. Summary of Almost 20 Years of Storm Overflight Electric Field, Conductivity, Flash Rates, and Electric Current Statistics

    NASA Technical Reports Server (NTRS)

    Blakeslee, Richard J.; Mach, Douglas M.; Bateman, Monte J.; Bailey, Jeffrey C.

    2011-01-01

    We determined total conduction currents and flash rates for around 900 high-altitude aircraft overflights of electrified clouds over 17 years. The overflights include a wide geographical sample of storms over land and ocean, with and without lightning, and with positive (i.e., upward-directed) and negative current. Peak electric field, with lightning transients removed, ranged from -1.0 kV m(sup -1) to 16. kV m(sup -1), with mean (median) of 0.9 kV m(sup -1) (0.29 kV m(sup -1)). Total conductivity at flight altitude ranged from 0.6 pS m(sup -1) to 3.6 pS m(sup -1), with mean and median of 2.2 pS m(sup -1). Peak current densities ranged from -2.0 nA m(sup -2) to 33.0 nA m(sup -2) with mean (median) of 1.9 nA m(sup -2) (0.6 nA m(sup -2)). Total upward current flow from storms in our dataset ranged from -1.3 to 9.4 A. The mean current for storms with lightning is 1.6 A over ocean and 1.0 A over land. The mean current for electrified shower clouds (i.e. electrified storms without lightning) is 0.39 A for ocean and 0.13 A for land. About 78% (43%) of the land (ocean) storms have detectable lightning. Land storms have 2.8 times the mean flash rate as ocean storms (2.2 versus 0.8 flashes min(sup -1), respectively). Approximately 7% of the overflights had negative current. The mean and median currents for positive (negative) polarity storms are 1.0 and 0.35 A (-0.30 and -0.26 A). We found no regional or latitudinal-based patterns in our storm currents, nor support for simple scaling laws between cloud top height and lightning flash rate.

  14. Summary of Almost 20 Years of Storm Overflight Electric Field, Conductivity, Flash Rate, and Current Statistics

    NASA Technical Reports Server (NTRS)

    Blakeslee, Richard J.; Mach, Douglas M.; Bateman, Monte J.; Bailey, Jeffrey C.

    2011-01-01

    We present total conduction (Wilson) currents for more than 1000 high-altitude aircraft overflights of electrified clouds acquired over nearly two decades. The overflights include a wide geographical sample of storms over land and ocean, with and without lightning, and with positive (i.e., upward-directed) and negative current. Peak electric field, with lightning transients removed, ranged from -1.0 kV/m to 16. kV/m, with mean (median) of 0.9 kV/m (0.29 kV/m). Total conductivity at flight altitude ranged from 0.6 pS/m to 3.6 pS/m, with mean and median of 2.2 pS/m. Peak current densities ranged from -2.0 nA m(exp -2) to 33.0 nA m(exp -2) with mean (median) of 1.9 nA m(exp -2) (0.6 nA m(exp -2)). Total upward current flow from storms in our dataset ranged from -1.3 to 9.4 A. The mean current for storms with lightning is 1.7 A over ocean and 1.0 A over land. The mean current for electrified shower clouds (i.e. electrified storms without lightning) is 0.41 A for ocean and 0.13 A for land. About 78% (43%) of the land (ocean) storms have detectable lightning. Land storms have 2.8 times the mean flash rate as ocean storms (2.2 versus 0.8 flashes min-1, respectively). Approximately 7% of the overflights had negative current. The mean and median currents for positive (negative) polarity storms are 1.0 and 0.35 A (-0.30 and -0.26 A). We found no regional or latitudinal-based patterns in our storm currents, nor support for simple scaling laws between cloud top height and lightning flash rate.

  15. [Geomagnetic storm decreases coherence of electric oscillations of human brain while working at the computer].

    PubMed

    Novik, O B; Smirnov, F A

    2013-01-01

    The effect of geomagnetic storms at the latitude of Moscow on the electric oscillations of the human brain cerebral cortex was studied. In course of electroencephalogram measurements it was shown that when the voluntary persons at the age of 18-23 years old were performing tasks using a computer during moderate magnetic storm or no later than 24 hrs after it, the value of the coherence function of electric oscillations of the human brain in the frontal and occipital areas in a range of 4.0-7.9 Hz (so-called the theta rhythm oscillations of the human brain) decreased by a factor of two or more, sometimes reaching zero, although arterial blood pressure, respiratory rate and the electrocardiogram registered during electroencephalogram measurements remained within the standard values.

  16. Storming the Bastille: the effect of electric fields on the ionospheric F-layer

    NASA Astrophysics Data System (ADS)

    Rishbeth, H.; Heelis, R. A.; Makela, J. J.; Basu, S.

    2010-04-01

    We discuss different phenomena occurring during ionospheric F-region storms that in principle might be caused by electric fields and point out challenges that must be faced when considering the physical processes at work. We consider the transport of plasma across many degrees of latitude at sub-auroral latitudes, the origin of patches of so-called "storm enhanced density" at high mid-latitudes, and the very high reported heights of the F2 peak at low latitudes. We discuss the role that electric fields might play in changing locally the net production of ionization as well as transporting it. We suggest that the local change in ionization production should be considered as a more important process for producing plasma density enhancements than transport from a more remote source of enhanced density.

  17. Electrically Conductive Chitosan/Carbon Scaffolds for Cardiac Tissue Engineering

    PubMed Central

    2015-01-01

    In this work, carbon nanofibers were used as doping material to develop a highly conductive chitosan-based composite. Scaffolds based on chitosan only and chitosan/carbon composites were prepared by precipitation. Carbon nanofibers were homogeneously dispersed throughout the chitosan matrix, and the composite scaffold was highly porous with fully interconnected pores. Chitosan/carbon scaffolds had an elastic modulus of 28.1 ± 3.3 KPa, similar to that measured for rat myocardium, and excellent electrical properties, with a conductivity of 0.25 ± 0.09 S/m. The scaffolds were seeded with neonatal rat heart cells and cultured for up to 14 days, without electrical stimulation. After 14 days of culture, the scaffold pores throughout the construct volume were filled with cells. The metabolic activity of cells in chitosan/carbon constructs was significantly higher as compared to cells in chitosan scaffolds. The incorporation of carbon nanofibers also led to increased expression of cardiac-specific genes involved in muscle contraction and electrical coupling. This study demonstrates that the incorporation of carbon nanofibers into porous chitosan scaffolds improved the properties of cardiac tissue constructs, presumably through enhanced transmission of electrical signals between the cells. PMID:24417502

  18. Mid-Latitude Dayside Ionospheric Response to Storm-Time Electric Fields

    NASA Astrophysics Data System (ADS)

    David, M.; Sojka, J. J.; Schunk, R. W.; Liemohn, M. W.

    2010-12-01

    One way in which a geomagnetic storm may impact the ionosphere is through an expansion of the magnetospheric electric field to mid-latitudes. This mechanism was explored in detail by Heelis et al [2009], where it was shown that an electric field with a magnitude of just 1 mV/m at mid-latitudes is sufficient to produce a large increase in TEC on the dayside. This effect is brought about by the lifting of the ionosphere as dayside plasma is transported poleward under the influence of the eastward component of the expanded electric field; the lifting occurs because of the inclination of the magnetic field lines. At the time the above-mentioned article was written, the authors lacked a physics-based modeling capability for the behavior of the storm-time electric field at mid-latitudes, so a simple modified form of the Volland 2-cell model was used. In the present work we use the University of Michigan’s Hot Electron and Ion Drift Integrator (HEIDI) electric field model, along with the Utah State University Time Dependent Ionospheric Model (TDIM). The HEIDI model provides electric potential distributions spanning the northern mid-latitudes with a cadence of 30 minutes; these are used to drive the TDIM in carrying out mid-latitude simulations. The results are compared with model runs for the quiet-time ionosphere, as well as observations from ionosondes and ground-based GPS TEC receivers. ----------------- Heelis, R. A., J. J. Sojka, M. David, and R. W. Schunk (2009), Storm time density enhancements in the middle-latitude dayside ionosphere, J. Geophys. Res., 114, A03315, doi:10.1029/2008JA013690.

  19. Electrical and Mechanical Strategies to Enable Cardiac Repair and Regeneration

    PubMed Central

    Cao, Hung; Kang, Bong Jin; Lee, Chia-An; Shung, K. Kirk; Hsiai, Tzung K.

    2015-01-01

    Inadequate replacement of lost ventricular myocardium from myocardial infarction leads to heart failure. Investigating the regenerative capacity of mammalian hearts represents an emerging direction for tissue engineering and cell-based therapy. Recent advances in stem cells hold promise to restore cardiac functions. However, embryonic or induced pluripotent stem cell-derived cardiomyocytes lack functional phenotypes of the native myocardium, and transplanted tissues are not fully integrated for synchronized electrical and mechanical coupling with the host. In this context, this review highlights the mechanical and electrical strategies to promote cardiomyocyte maturation and integration, and to assess the functional phenotypes of regenerating myocardium. Simultaneous micro-electrocardiogram and high-frequency ultrasound techniques will also be introduced to assess electrical and mechanical coupling for small animal models of heart regeneration. PMID:25974948

  20. Summary of the NASA/MSFC FY-79 Severe Storm and Local Weather research review. [cloud physics, atmospheric electricity, and mesoscale/storm dynamics reserach

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Significant acomplishments, current focus of work, plans for FY-80, and recommendations for new research are outlined for 36 research projects proposed for technical monitoring by the Atmospheric Sciences Division at Marshall Space Flight Center. Topics of the investigations, which were reviewed at a two-day meeting, relate to cloud physics, atmospheric electricity, and mesoscale/storm dynamics.

  1. Influence of the Convection Electric Field Models on Predicted Plasmapause Positions During Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Pierrard, V.; Khazanov, G.; Cabrera, J.; Lemaire, J.

    2007-01-01

    In the present work, we determine how three well documented models of the magnetospheric electric field, and two different mechanisms proposed for the formation of the plasmapause influence the radial distance, the shape and the evolution of the plasmapause during the geomagnetic storms of 28 October 2001 and of 17 April 2002. The convection electric field models considered are: Mcllwain's E51) electric field model, Volland-Stern's model and Weimer's statistical model compiled from low-Earth orbit satellite data. The mechanisms for the formation of the plasmapause to be tested are: (i) the MHD theory where the plasmapause should correspond to the last-closed- equipotential (LCE) or last-closed-streamline (LCS), if the E-field distribution is stationary or time-dependent respectively; (ii) the interchange mechanism where the plasmapause corresponds to streamlines tangent to a Zero-Parallel-Force surface where the field-aligned plasma distribution becomes convectively unstable during enhancements of the E-field intensity in the nightside local time sector. The results of the different time dependent simulations are compared with concomitant EUV observations when available. The plasmatails or plumes observed after both selected geomagnetic storms are predicted in all simulations and for all E-field models. However, their shapes are quite different depending on the E-field models and the mechanisms that are used. Despite the partial success of the simulations to reproduce plumes during magnetic storms and substorms, there remains a long way to go before the detailed structures observed in the EUV observations during periods of geomagnetic activity can be accounted for very precisely by the existing E-field models. Furthermore, it cannot be excluded that the mechanisms currently identified to explain the formation of "Carpenter's knee" during substorm events, will', have to be revised or complemented in the cases of geomagnetic storms.

  2. Practical aspects of cardiac tissue engineering with electrical stimulation.

    PubMed

    Cannizzaro, Christopher; Tandon, Nina; Figallo, Elisa; Park, Hyoungshin; Gerecht, Sharon; Radisic, Milica; Elvassore, Nicola; Vunjak-Novakovic, Gordana

    2007-01-01

    Heart disease is a leading cause of death in western society. Despite the success of heart transplantation, a chronic shortage of donor organs, along with the associated immunological complications of this approach, demands that alternative treatments be found. One such option is to repair, rather than replace, the heart with engineered cardiac tissue. Multiple studies have shown that to attain functional tissue, assembly signaling cues must be recapitulated in vitro. In their native environment, cardiomyocytes are directed to beat in synchrony by propagation of pacing current through the tissue. Recently, we have shown that electrical stimulation directs neonatal cardiomyocytes to assemble into native-like tissue in vitro. This chapter provides detailed methods we have employed in taking this "biomimetic" approach. After an initial discussion on how electric field stimulation can influence cell behavior, we examine the practical aspects of cardiac tissue engineering with electrical stimulation, such as electrode selection and cell seeding protocols, and conclude with what we feel are the remaining challenges to be overcome.

  3. Post-Storm Middle and Low-Latitude Ionospheric Electric Fields Effects

    NASA Astrophysics Data System (ADS)

    Fejer, B. G.; Blanc, M.; Richmond, A. D.

    2017-03-01

    The Earth's upper atmosphere and ionosphere undergoes large and complex perturbations during and after geomagnetic storms. Thermospheric winds driven by enhanced energy and momentum due to geomagnetic activity generate large disturbance electric fields, plasma drifts and currents with a broad range of temporal and spatial scales from high to equatorial latitudes. This disturbance dynamo mechanism plays a fundamental role on the response of the middle and low-latitude ionosphere to geomagnetic activity. In this review, we initially describe the early evidence for the importance of this process and the first simulation study which already was able to explain its main effects on the electrodynamics of the middle and low-latitude ionosphere. We then describe the results of more recent simulations and the extensive experimental work that highlights the importance of this mechanism for ionospheric space weather studies extending to post-storms periods, and present some suggestions for future studies.

  4. Post-Storm Middle and Low-Latitude Ionospheric Electric Fields Effects

    NASA Astrophysics Data System (ADS)

    Fejer, B. G.; Blanc, M.; Richmond, A. D.

    2016-12-01

    The Earth's upper atmosphere and ionosphere undergoes large and complex perturbations during and after geomagnetic storms. Thermospheric winds driven by enhanced energy and momentum due to geomagnetic activity generate large disturbance electric fields, plasma drifts and currents with a broad range of temporal and spatial scales from high to equatorial latitudes. This disturbance dynamo mechanism plays a fundamental role on the response of the middle and low-latitude ionosphere to geomagnetic activity. In this review, we initially describe the early evidence for the importance of this process and the first simulation study which already was able to explain its main effects on the electrodynamics of the middle and low-latitude ionosphere. We then describe the results of more recent simulations and the extensive experimental work that highlights the importance of this mechanism for ionospheric space weather studies extending to post-storms periods, and present some suggestions for future studies.

  5. Atmospheric Electrical Modeling in Support of the NASA F-106 Storm Hazards Project

    NASA Technical Reports Server (NTRS)

    Helsdon, John H., Jr.

    1988-01-01

    A recently developed storm electrification model (SEM) is used to investigate the operating environment of the F-106 airplane during the NASA Storm Hazards Project. The model is 2-D, time dependent and uses a bulkwater microphysical parameterization scheme. Electric charges and fields are included, and the model is fully coupled dynamically, microphysically and electrically. One flight showed that a high electric field was developed at the aircraft's operating altitude (28 kft) and that a strong electric field would also be found below 20 kft; however, this low-altitude, high-field region was associated with the presence of small hail, posing a hazard to the aircraft. An operational procedure to increase the frequency of low-altitude lightning strikes was suggested. To further the understanding of lightning within the cloud environment, a parameterization of the lightning process was included in the SEM. It accounted for the initiation, propagation, termination, and charge redistribution associated with an intracloud discharge. Finally, a randomized lightning propagation scheme was developed, and the effects of cloud particles on the initiation of lightning investigated.

  6. Electric Field Influence on Driving the Storm-Time Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Zaharia, S. G.; Jordanova, V. K.; MacDonald, E.; Reeves, G. D.

    2013-05-01

    We present initial numerical simulation results of the storm-time near-Earth magnetosphere obtained with our newly improved self-consistent model, RAM-SCB. The model represents a 2-way coupling of the kinetic ring current-atmosphere interactions model (RAM) with an Euler potential-based 3D plasma equilibrium code. In our approach, the magnetic field is computed in force balance with the anisotropic pressures in RAM (anisotropy being critically important for wave excitation), and then returned to RAM to guide the particle dynamics. RAM-SCB thus properly treats both the kinetic drift physics crucial in the inner magnetosphere (where gradient/curvature drifts are important) and the self-consistent interaction between plasma and magnetic field (required due to the strong depressions in the field during storms that affect the plasma evolution). Recent improvements in RAM-SCB are the expansion of the boundary from geosynchronous location to 9 RE from Earth and the first-time inclusion of a self-consistent electric field, obtained by closing the field-aligned currents in the ionosphere. This extension makes RAM-SCB the most physically complete inner magnetosphere model in the community, with fully self-consistent 3D magnetic and electric fields. The presentation will analyze, using storm-time simulations of the near-Earth magnetosphere with the improved model, the effect of the self-consistent electric field on ring current dynamics, in comparison with empirical electric field models such as Weimer 01 and Volland/Stern models. We will also compare model results with observations (including global indices such as Dst, but also plasma and field data from available spacecraft, such as Polar, Cluster, GOES and the recently launched Van Allen Probes).

  7. [A case of electrical storm in a patient with short-coupled variant of torsade de pointes].

    PubMed

    Conte, Giulio; Coppini, Lucia; Demola, Maria Antonietta; Ardissino, Diego

    2013-01-01

    Short-coupled variant of torsade de pointes (TdP) is an uncommon variant of polymorphic ventricular tachycardia with unknown etiology. It is initiated by a closely coupled premature ventricular complex (<300 ms) in the absence of QT prolongation and structural heart disease. Verapamil seems to be the only drug able to suppress the arrhythmia but, as it does not reduce the risk of sudden death, implantation of a cardioverter-defibrillator (ICD) is recommended. We describe the case of a 46-year-old woman referred to our Emergency Department because of palpitations. The initial ECG showed a non-sustained polymorphic ventricular tachycardia with a borderline QTc interval (450 ms). After admission, the patient experienced an episode of TdP that started after short-coupling interval (280 ms) between the last sinus beat and the ventricular premature beat (VPB). DC-shock restored sinus rhythm. Physical examination, exercise testing, echocardiography and cardiac magnetic resonance were all normal, and she had no family history of sudden cardiac death. Baseline ECG showed sinus rhythm and unifocal VPBs with the same morphology of the VPB of TdP. The patient received an ICD and was treated medically with verapamil. She was discharged from the hospital on oral therapy with verapamil (240 mg/day), and she was free of recurrence 12 months later when an electrical storm occurred. The verapamil dose was therefore increased to 480 mg/day. Unifocal VPBs disappeared from her body surface ECG, and the subsequent 3-year follow-up was uneventful.

  8. Effects of disturbed electric fields in the low-latitude and equatorial ionosphere during the 2015 St. Patrick's Day storm

    NASA Astrophysics Data System (ADS)

    Kuai, Jiawei; Liu, Libo; Liu, Jing; Sripathi, S.; Zhao, Biqiang; Chen, Yiding; Le, Huijun; Hu, Lianhuan

    2016-09-01

    The 2015 St. Patrick's Day geomagnetic storm with SYM-H value of -233 nT is an extreme space weather event in the current 24th solar cycle. In this work, we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the Asian-Australian sector and the American sector during this super storm event. The results reveal that the disturbed electric fields, which comprise penetration electric fields (PEFs) and disturbance dynamo electric fields (DDEFs), play a decisive role in the ionospheric storm effects in low latitude and equatorial regions. PEFs occur on 17 March in both the American sector and the Asian-Australian sector. The effects of DDEFs are also remarkable in the two longitudinal sectors. Both the DDEFs and PEFs show the notable local time dependence, which causes the sector differences in the characteristics of the disturbed electric fields. This differences would further lead to the sector differences in the low-latitude ionospheric response during this storm. The negative storm effects caused by the long-duration DDEFs are intense over the Asian-Australian sector, while the repeated elevations of hmF2 and the equatorial ionization anomaly intensifications caused by the multiple strong PEFs are more distinctive over the American sector. Especially, the storm time F3 layer features are caught on 17 March in the American equatorial region, proving the effects of the multiple strong eastward PEFs.

  9. Effect of Precipitating Electrons on Stormtime Inner Magnetospheric Electric Fields during the 17 March 2013 Storm

    NASA Astrophysics Data System (ADS)

    Chen, M.; Lemon, C. L.; Sazykin, S. Y.; Wolf, R.; Hecht, J. H.; Walterscheid, R. L.; Boyd, A. J.; Turner, D. L.

    2015-12-01

    We investigate how scattering of electrons by waves in the plasma sheet and plasmasphere affects precipitating energy flux distributions and how the precipitating electrons modify the ionospheric conductivity and electric potentials during the large 17 March 2013 magnetic storm. Of particular interest is how electron precipitation in the evening sector affects the development of the Sub-auroral Polarization Stream (SAPS) electric field that is observed at sub-auroral latitudes in that sector. Our approach is to use the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) of the inner magnetosphere to simulate the stormtime precipitating electron distributions and the electric field. We use parameterized rates of whistler-generated electron pitch-angle scattering from Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time (MLT) outside the simulated plasmasphere. Inside the plasmasphere, parameterized scattering rates due to hiss [Orlova et al., GRL, 2014] are used. We compare simulated trapped and precipitating electron flux distributions with measurements from Van Allen Probes/MagEIS, POES/TED and MEPED, respectively, to validate the electron loss model. Ground-based (SuperDARN) and in-situ (Van Allen Probes/EFW) observations of electric fields are compared with the simulation results. We discuss the effect of precipitating electrons on the SAPS and inner magnetospheric electric field through the data-model comparisons.

  10. Subtle alternating electrocardiographic morphology as an indicator of decreased cardiac electrical stability

    NASA Technical Reports Server (NTRS)

    Smith, J. M.; Blue, B.; Clancy, E.; Valeri, C. R.; Cohen, R. J.

    1985-01-01

    Observations from finite-element computer models, together with analytic developments based on percolation theory have suggested that subtle fluctuations of ECG morphology might serve as an indicator diminished cardiac electrical stability. With fixed-rate atrial pacing in canines, we have previously observed a pattern of alternation in T wave energy which correlated with cardiac electrical stability. We report here on a series of 20 canine experiments in which cardiac electrical stability (measured via Ventricular Fibrillation Threshold determination) was compared to a non-degenerate, multidimensional measurement of the degree of alternating activity present in the ECG complex morphology. The decrease in cardiac electrical stability brought on by both coronary artery occlusion and systemic hypothermia was consistently accompanied by subtle alternation in ECG morphology, with the absolute degree of alternating activity being significantly (negatively) correlated with cardiac electrical stability.

  11. Cardiac thrombus developing after an accidental high-voltage electric shock in a child.

    PubMed

    Akın, Alper; Bilici, Meki; Demir, Fikri; Gözü Pirinççioğlu, Ayfer; Yavuz, Celal

    2015-01-01

    Electric shock is a condition that may affect various organ systems and potentially cause death. Cardiac findings vary from asymptomatic mild injury to fatal myocardial involvement. Herein we present a five-year-old boy with a cardiac thrombus developing after an accidental electrical shock. Cardiac arrhythmias and evidence of ischemia have been reported after electric shock; we were, however, unable to identify an earlier case report of intracardiac thrombosis related to electric shock. Findings such as elevated cardiac enzymes and systolic dysfunction, which indicate myocardial damage following electric shock, were present in our patient. We think that the cardiac thrombus might have resulted from the myocardial damage and the slowed intracardiac blood flow related to systolic dysfunction. As the thrombus was thought to have been formed through known mechanisms, it was treated traditionally. However, further data regarding the etiology and management of such thrombi is needed.

  12. Analysis of Van Allen Probes Data Showing Nonlinear Electric Field Feedback During a Magnetic Storm

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Katus, R. M.; Smith, L. K.; Skoug, R. M.; Niehof, J. T.; Spence, H.; Wygant, J. R.; Bonnell, J. W.; Smith, C. W.; Kletzing, C.; Ilie, R.; Ganushkina, N.

    2013-12-01

    Van Allen Probes data was examined to assess the role of nonlinear feedback in relationship to the spatial structure of hot ions in the inner magnetosphere. During the magnetic storm that peaked on June 1, 2013, localized electric field perturbations from the EFW instrument were observed in relationship to the plasma pressure peak (as identified by the HOPE H+ and O+ fluxes in the 1-40 keV range, as well as magnetic field perturbations from EMFISIS) with a systematic sinusoidal perturbation. Near apogee, it takes the Van Allen Probes 30-60 minutes to traverse a peak in the ion fluxes. Therefore, the electric field was averaged over several minutes to remove the higher-frequency wave oscillations, revealing the longer-baseline perturbation associated with the pressure peak. While the fluxes indicate that the satellite is passing through a pressure peak, the magnetic field perturbation reveals the spatial location of the pressure extrema relative to the spacecraft location. The pattern of these electric fields relative to the location of the plasma pressure peak is in agreement with the hypothesis based on theory and numerical simulation results that an azimuthally localized pressure peak should create a systematic and predictable small-scale reconfiguration of the electric field. This electric field modification is because the field-aligned currents near each end of the pressure crescent close via Pedersen currents, perturbing the electric field in this region, as regulated by the ionospheric conductance. The level of this reconfiguration, relative to the expected dawn-dusk electric field within the magnetosphere, indicates the intensity of the nonlinear feedback.

  13. Pulseless electrical activity in cardiac arrest: electrocardiographic presentations and management considerations based on the electrocardiogram.

    PubMed

    Mehta, Chris; Brady, William

    2012-01-01

    Pulseless electrical activity (PEA), a cardiac arrest rhythm scenario with an associated poor prognosis, is defined as cardiac electrical activity without a palpable pulse. Considering both outpatient and inpatient cardiac arrest presentations, PEA as a rhythm group has been increasing over the past 10 to 20 years with a corresponding decrease in the "shockable" rhythms, such as pulseless ventricular tachycardia and ventricular fibrillation. This review focuses on electrocardiographic findings encountered in PEA cardiac arrest presentations with an emphasis on recognition of patients with a potential opportunity for successful resuscitation.

  14. Electrical stimulation of cardiac adipose tissue-derived progenitor cells modulates cell phenotype and genetic machinery.

    PubMed

    Llucià-Valldeperas, A; Sanchez, B; Soler-Botija, C; Gálvez-Montón, C; Prat-Vidal, C; Roura, S; Rosell-Ferrer, J; Bragos, R; Bayes-Genis, A

    2015-11-01

    A major challenge of cardiac tissue engineering is directing cells to establish the physiological structure and function of the myocardium being replaced. Our aim was to examine the effect of electrical stimulation on the cardiodifferentiation potential of cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs). Three different electrical stimulation protocols were tested; the selected protocol consisted of 2 ms monophasic square-wave pulses of 50 mV/cm at 1 Hz over 14 days. Cardiac and subcutaneous ATDPCs were grown on biocompatible patterned surfaces. Cardiomyogenic differentiation was examined by real-time PCR and immunocytofluorescence. In cardiac ATDPCs, MEF2A and GATA-4 were significantly upregulated at day 14 after stimulation, while subcutaneous ATDPCs only exhibited increased Cx43 expression. In response to electrical stimulation, cardiac ATDPCs elongated, and both cardiac and subcutaneous ATDPCs became aligned following the linear surface pattern of the construct. Cardiac ATDPC length increased by 11.3%, while subcutaneous ATDPC length diminished by 11.2% (p = 0.013 and p = 0.030 vs unstimulated controls, respectively). Compared to controls, electrostimulated cells became aligned better to the patterned surfaces when the pattern was perpendicular to the electric field (89.71 ± 28.47º for cardiac ATDPCs and 92.15 ± 15.21º for subcutaneous ATDPCs). Electrical stimulation of cardiac ATDPCs caused changes in cell phenotype and genetic machinery, making them more suitable for cardiac regeneration approaches. Thus, it seems advisable to use electrical cell training before delivery as a cell suspension or within engineered tissue.

  15. Analysis of electric field stimulation of single cardiac muscle cells.

    PubMed Central

    Tung, L; Borderies, J R

    1992-01-01

    Electrical stimulation of cardiac cells by imposed extracellular electric fields results in a transmembrane potential which is highly nonuniform, with one end of the cell depolarized and the other end hyperpolarized along the field direction. To date, the implications of the close proximity of oppositely polarized membranes on excitability have not been explored. In this work we compare the biophysical basis for field stimulation of cells at rest with that for intracellular current injection, using three Luo-Rudy type membrane patches coupled together as a lumped model to represent the cell membrane. Our model shows that cell excitation is a function of the temporal and spatial distribution of ionic currents and transmembrane potential. The extracellular and intracellular forms of stimulation were compared in greater detail for monophasic and symmetric biphasic rectangular pulses, with duration ranging from 0.5 to 10 ms. Strength-duration curves derived for field stimulation show that over a wide range of pulse durations, biphasic waveforms can recruit and activate membrane patches about as effectively as can monophasic waveforms having the same total pulse duration. We find that excitation with biphasic stimulation results from a synergistic, temporal summation of inward currents through the sodium channel in membrane patches at opposite ends of the cell. Furthermore, with both waveform types, a net inward current through the inwardly rectifying potassium channel contributes to initial membrane depolarization. In contrast, models of stimulation by intracellular current injection do not account for the nonuniformity of transmembrane potential and produce substantially different (even contradictory) results for the case of stimulation from rest. PMID:1420884

  16. Reproducing Electric Field Observations during Magnetic Storms by means of Rigorous 3-D Modelling and Distortion Matrix Co-estimation

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Manoj, Chandrasekharan; Kuvshinov, Alexey

    2015-04-01

    Electric fields induced in the conducting Earth during magnetic storms drive currents in power transmission grids, telecommunication lines or buried pipelines. These geomagnetically induced currents (GIC) can cause severe service disruptions. The prediction of GIC is thus of great importance for public and industry. A key step in the prediction of the hazard to technological systems during magnetic storms is the calculation of the geoelectric field. To address this issue for mid-latitude regions, we developed a method that involves 3-D modelling of induction processes in a heterogeneous Earth and the construction of a model of the magnetospheric source. The latter is described by low-degree spherical harmonics; its temporal evolution is derived from observatory magnetic data. Time series of the electric field can be computed for every location on Earth's surface. The actual electric field however is known to be perturbed by galvanic effects, arising from very local near-surface heterogeneities or topography, which cannot be included in the conductivity model. Galvanic effects are commonly accounted for with a real-valued time-independent distortion matrix, which linearly relates measured and computed electric fields. Using data of various magnetic storms that occurred between 2000 and 2003, we estimated distortion matrices for observatory sites onshore and on the ocean bottom. Strong correlations between modellings and measurements validate our method. The distortion matrix estimates prove to be reliable, as they are accurately reproduced for different magnetic storms. We further show that 3-D modelling is crucial for a correct separation of galvanic and inductive effects and a precise prediction of electric field time series during magnetic storms. Since the required computational resources are negligible, our approach is suitable for a real-time prediction of GIC. For this purpose, a reliable forecast of the source field, e.g. based on data from satellites

  17. Electrical Stimulation Promotes Cardiac Differentiation of Human Induced Pluripotent Stem Cells

    PubMed Central

    Hernández, Damián; Millard, Rodney; Sivakumaran, Priyadharshini; Wong, Raymond C. B.; Crombie, Duncan E.; Hewitt, Alex W.; Liang, Helena; Hung, Sandy S. C.; Pébay, Alice; Shepherd, Robert K.; Dusting, Gregory J.; Lim, Shiang Y.

    2016-01-01

    Background. Human induced pluripotent stem cells (iPSCs) are an attractive source of cardiomyocytes for cardiac repair and regeneration. In this study, we aim to determine whether acute electrical stimulation of human iPSCs can promote their differentiation to cardiomyocytes. Methods. Human iPSCs were differentiated to cardiac cells by forming embryoid bodies (EBs) for 5 days. EBs were then subjected to brief electrical stimulation and plated down for 14 days. Results. In iPS(Foreskin)-2 cell line, brief electrical stimulation at 65 mV/mm or 200 mV/mm for 5 min significantly increased the percentage of beating EBs present by day 14 after plating. Acute electrical stimulation also significantly increased the cardiac gene expression of ACTC1, TNNT2, MYH7, and MYL7. However, the cardiogenic effect of electrical stimulation was not reproducible in another iPS cell line, CERA007c6. Beating EBs from control and electrically stimulated groups expressed various cardiac-specific transcription factors and contractile muscle markers. Beating EBs were also shown to cycle calcium and were responsive to the chronotropic agents, isoproterenol and carbamylcholine, in a concentration-dependent manner. Conclusions. Our results demonstrate that brief electrical stimulation can promote cardiac differentiation of human iPS cells. The cardiogenic effect of brief electrical stimulation is dependent on the cell line used. PMID:26788064

  18. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  19. Van Allen Probes based investigation of storm time plasmasphere erosion and earthward penetration of the convection electric field

    NASA Astrophysics Data System (ADS)

    Thaller, S. A.; Wygant, J. R.; Dai, L.; Breneman, A. W.; Kersten, K.; Kletzing, C.; Kurth, W. S.; Bonnell, J. W.; De Pascuale, S.; Hospodarsky, G. B.; Bounds, S. R.

    2013-12-01

    Using the Van Allen Probes we investigate the erosion of the plasmasphere as well as the evolution in location of the plasmapause during large storms (Dst < -100 nT). In addition, we also examine the penetration of the large scale storm-time convection electric field to low L ( < 3 RE) and its role in erosion of the plasmasphere. The enhanced convection electric field penetrates to low L during large storms, and a tangible effect on plasmasphere erosion is observed at low L. The plasmaspause is identified through the UHR line in EMFISIS high frequency spectral data and plasma densities determined from calibration fits to the spacecraft potential from the EFW instrument; such fits are also presented herein. During large storms the plasmapause can move to within L~1.9 RE of the earth. The erosion of the plasmasphere and consequent inward movement of the plasmapause to low L from quite time locations (4-5 RE) occurs within less than one orbit period (~9hr).

  20. Three dimensional graphene scaffold for cardiac tissue engineering and in-situ electrical recording.

    PubMed

    Ameri, S K; Singh, P K; D'Angelo, R; Stoppel, W; Black, L; Sonkusale, S R

    2016-08-01

    In this paper, we present a three-dimensional graphene foam made of few layers of CVD grown graphene as a scaffold for growing cardiac cells and recording their electrical activity. Our results show that graphene foam not only provides an excellent extra-cellular matrix (ECM) for the culture of such electrogenic cells but also enables recording of its extracellular electrical activity in-situ. Recording is possible due to graphene's excellent conductivity. In this paper, we present our results on the fabrication of the graphene scaffold and initial studies on the culture of cardiac cell lines such as HL-1 and recording of their real-time electrical activity.

  1. Reproducing electric field observations during magnetic storms by means of rigorous 3-D modelling and distortion matrix co-estimation

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Manoj, Chandrasekharan; Kuvshinov, Alexey

    2014-12-01

    Electric fields induced in the conducting Earth by geomagnetic disturbances drive currents in power transmission grids, telecommunication lines or buried pipelines, which can cause service disruptions. A key step in the prediction of the hazard to technological systems during magnetic storms is the calculation of the geoelectric field. To address this issue for mid-latitude regions, we revisit a method that involves 3-D modelling of induction processes in a heterogeneous Earth and the construction of a magnetospheric source model described by low-degree spherical harmonics from observatory magnetic data. The actual electric field, however, is known to be perturbed by galvanic effects, arising from very local near-surface heterogeneities or topography, which cannot be included in the model. Galvanic effects are commonly accounted for with a real-valued time-independent distortion matrix, which linearly relates measured and modelled electric fields. Using data of six magnetic storms that occurred between 2000 and 2003, we estimate distortion matrices for observatory sites onshore and on the ocean bottom. Reliable estimates are obtained, and the modellings are found to explain up to 90% of the measurements. We further find that 3-D modelling is crucial for a correct separation of galvanic and inductive effects and a precise prediction of the shape of electric field time series during magnetic storms. Since the method relies on precomputed responses of a 3-D Earth to geomagnetic disturbances, which can be recycled for each storm, the required computational resources are negligible. Our approach is thus suitable for real-time prediction of geomagnetically induced currents by combining it with reliable forecasts of the source field.

  2. Response of the Fair Weather Atmospheric Electrical Current to Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Yair, Yoav; Price, Colin; Elhalal, Gal

    2013-04-01

    The Global Electric Circuit (GEC) is a conceptual model that integrates the observed electrical properties of the atmosphere in the Earth-ionosphere cavity. An average potential difference of 250 kV exists between these two conducting layers, leading to a surface electric field (Ez, sometimes also named the Potential Gradient or PG) of ~130 V/m, and a nearly constant downward flowing direct current density (Jz) of ~2 pA m-2. This is known as the DC component of the GEC. The Jz is an extremely sensitive parameter whose magnitude and fluctuations can be used for monitoring local and global conductivity changes due to aerosols, air-pollution and solar activity. The AC part of the circuit is driven by ~50 lightning flashes per second generating the global Schumann resonances (SR) in the ELF range. There are two time-scales for identifying solar effects on the GEC. On the longer scale, an 11-year modulation by solar activity, likely due to changes in ionization, was reported by several authors. For example, Satori et al. (2005) noted a decrease in the frequency of the first 3 modes of the SR band in conjunction with the solar minimum of 1995-6. On shorter time scales typical of solar activity (e.g. CMEs, solar flares and SEP events), observations show marked perturbations in Jz and in the ionospheric potential at the surface. Cobb (1967) observed an increase of Jz by 75% for ~ 6 h in measurements made at Mauna Loa in Hawaii, during a period of multiple solar flares. Reiter (1989) observed an increase in Jz of about 50%-60% following large solar flares, persisting for 4 days (at the Zungspietze station in the Alps). Belova et al. (2001) reported increased Jz for about 2 hours before T=0 (time of minimum in Bx) as well as enhanced average fluctuations. This talk will review the effects of solar storms on the GEC, and present new results from continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35'N, 34°45'E). During 3 different

  3. Reversible cardiac conduction block and defibrillation with high-frequency electric field.

    PubMed

    Tandri, Harikrishna; Weinberg, Seth H; Chang, Kelly C; Zhu, Renjun; Trayanova, Natalia A; Tung, Leslie; Berger, Ronald D

    2011-09-28

    Electrical impulse propagation is an essential function in cardiac, skeletal muscle, and nervous tissue. Abnormalities in cardiac impulse propagation underlie lethal reentrant arrhythmias, including ventricular fibrillation. Temporary propagation block throughout the ventricular myocardium could possibly terminate these arrhythmias. Electrical stimulation has been applied to nervous tissue to cause reversible conduction block, but has not been explored sufficiently in cardiac tissue. We show that reversible propagation block can be achieved in cardiac tissue by holding myocardial cells in a refractory state for a designated period of time by applying a sustained sinusoidal high-frequency alternating current (HFAC); in doing so, reentrant arrhythmias are terminated. We demonstrate proof of concept using several models, including optically mapped monolayers of neonatal rat ventricular cardiomyocytes, Langendorff-perfused guinea pig and rabbit hearts, intact anesthetized adult rabbits, and computer simulations of whole-heart impulse propagation. HFAC may be an effective and potentially safer alternative to direct current application, currently used to treat ventricular fibrillation.

  4. Roles of electric field and fiber structure in cardiac electric stimulation.

    PubMed Central

    Knisley, S B; Trayanova, N; Aguel, F

    1999-01-01

    This study investigated roles of the variation of extracellular voltage gradient (VG) over space and cardiac fibers in production of transmembrane voltage changes (DeltaV(m)) during shocks. Eleven isolated rabbit hearts were arterially perfused with solution containing V(m)-sensitive fluorescent dye (di-4-ANEPPS). The epicardium received shocks from symmetrical or asymmetrical electrodes to produce nominally uniform or nonuniform VGs. Extracellular electric field and DeltaV(m) produced by shocks in the absolute refractory period were measured with electrodes and a laser scanner and were simulated with a bidomain computer model that incorporated the anterior left ventricular epicardial fiber field. Measurements and simulations showed that fibers distorted extracellular voltages and influenced the DeltaV(m). For both uniform and nonuniform shocks, DeltaV(m) depended primarily on second spatial derivatives of extracellular voltages, whereas the VGs played a smaller role. Thus, 1) fiber structure influences the extracellular electric field and the distribution of DeltaV(m); 2) the DeltaV(m) depend on second spatial derivatives of extracellular voltage. PMID:10465752

  5. Control of cardiac alternans by mechanical and electrical feedback

    NASA Astrophysics Data System (ADS)

    Yapari, Felicia; Deshpande, Dipen; Belhamadia, Youssef; Dubljevic, Stevan

    2014-07-01

    A persistent alternation in the cardiac action potential duration has been linked to the onset of ventricular arrhythmia, which may lead to sudden cardiac death. A coupling between these cardiac alternans and the intracellular calcium dynamics has also been identified in previous studies. In this paper, the system of PDEs describing the small amplitude of alternans and the alternation of peak intracellular Ca2+ are stabilized by optimal boundary and spatially distributed actuation. A simulation study demonstrating the successful annihilation of both alternans on a one-dimensional cable of cardiac cells by utilizing the full-state feedback controller is presented. Complimentary to these studies, a three variable Nash-Panfilov model is used to investigate alternans annihilation via mechanical (or stretch) perturbations. The coupled model includes the active stress which defines the mechanical properties of the tissue and is utilized in the feedback algorithm as an independent input from the pacing based controller realization in alternans annihilation. Simulation studies of both control methods demonstrate that the proposed methods can successfully annihilate alternans in cables that are significantly longer than 1 cm, thus overcoming the limitations of earlier control efforts.

  6. Biphasic Electrical Field Stimulation Aids in Tissue Engineering of Multicell-Type Cardiac Organoids

    PubMed Central

    Chiu, Loraine L.Y.; Iyer, Rohin K.; King, John-Paul

    2011-01-01

    The main objectives of current work were (1) to compare the effects of monophasic or biphasic electrical field stimulation on structure and function of engineered cardiac organoids based on enriched cardiomyocytes (CM) and (2) to determine if electrical field stimulation will enhance electrical excitability of cardiac organoids based on multiple cell types. Organoids resembling cardiac myofibers were cultivated in Matrigel-coated microchannels fabricated of poly(ethylene glycol)-diacrylate. We found that field stimulation using symmetric biphasic square pulses at 2.5 V/cm, 1 Hz, 1 ms (per pulse phase) was an improved stimulation protocol, as compared to no stimulation and stimulation using monophasic square pulses of identical total amplitude and duration (5 V/cm, 1 Hz, 2 ms). This was supported by the highest success rate for synchronous contractions, low excitation threshold, the highest cell density, and the highest expression of Connexin-43 in the biphasic group. Subsequently, enriched CM were seeded on the networks of (1) cardiac fibroblasts (FB), (2) D4T endothelial cells (EC), or (3) a mixture of FB and EC that were precultured for 2 days prior to the addition of enriched CM. Biphasic field stimulation was also effective at improving electrical excitability of these cardiac organoids by improving the three-dimensional organization of the cells, increasing cellular elongation and enhancing Connexin-43 presence. PMID:18783322

  7. Biphasic electrical field stimulation aids in tissue engineering of multicell-type cardiac organoids.

    PubMed

    Chiu, Loraine L Y; Iyer, Rohin K; King, John-Paul; Radisic, Milica

    2011-06-01

    The main objectives of current work were (1) to compare the effects of monophasic or biphasic electrical field stimulation on structure and function of engineered cardiac organoids based on enriched cardiomyocytes (CM) and (2) to determine if electrical field stimulation will enhance electrical excitability of cardiac organoids based on multiple cell types. Organoids resembling cardiac myofibers were cultivated in Matrigel-coated microchannels fabricated of poly(ethylene glycol)-diacrylate. We found that field stimulation using symmetric biphasic square pulses at 2.5 V/cm, 1 Hz, 1 ms (per pulse phase) was an improved stimulation protocol, as compared to no stimulation and stimulation using monophasic square pulses of identical total amplitude and duration (5 V/cm, 1 Hz, 2 ms). This was supported by the highest success rate for synchronous contractions, low excitation threshold, the highest cell density, and the highest expression of Connexin-43 in the biphasic group. Subsequently, enriched CM were seeded on the networks of (1) cardiac fibroblasts (FB), (2) D4T endothelial cells (EC), or (3) a mixture of FB and EC that were precultured for 2 days prior to the addition of enriched CM. Biphasic field stimulation was also effective at improving electrical excitability of these cardiac organoids by improving the three-dimensional organization of the cells, increasing cellular elongation and enhancing Connexin-43 presence.

  8. Wave trains induced by circularly polarized electric fields in cardiac tissues.

    PubMed

    Feng, Xia; Gao, Xiang; Tang, Juan-Mei; Pan, Jun-Ting; Zhang, Hong

    2015-08-25

    Clinically, cardiac fibrillation caused by spiral and turbulent waves can be terminated by globally resetting electric activity in cardiac tissues with a single high-voltage electric shock, but it is usually associated with severe side effects. Presently, a promising alternative uses wave emission from heterogeneities induced by a sequence of low-voltage uniform electric field pulses. Nevertheless, this method can only emit waves locally near obstacles in turbulent waves and thereby requires multiple obstacles to globally synchronize myocardium and thus to terminate fibrillation. Here we propose a new approach using wave emission from heterogeneities induced by a low-voltage circularly polarized electric field (i.e., a rotating uniform electric field). We find that, this approach can generate circular wave trains near obstacles and they propagate outwardly. We study the characteristics of such circular wave trains and further find that, the higher-frequency circular wave trains can effectively suppress spiral turbulence.

  9. Vortex shedding as a precursor of turbulent electrical activity in cardiac muscle.

    PubMed Central

    Cabo, C; Pertsov, A M; Davidenko, J M; Baxter, W T; Gray, R A; Jalife, J

    1996-01-01

    In cardiac tissue, during partial blockade of the membrane sodium channels, or at high frequencies of excitation, inexcitable obstacles with sharp edges may destabilize the propagation of electrical excitation waves, causing the formation of self-sustained vortices and turbulent cardiac electrical activity. The formation of such vortices, which visually resembles vortex shedding in hydrodynamic turbulent flows, was observed in sheep epicardial tissue using voltage-sensitive dyes in combination with video-imaging techniques. Vortex shedding is a potential mechanism leading to the spontaneous initiation of uncontrolled high-frequency excitation of the heart. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 PMID:8785270

  10. The 17 March 2013 storm: Synergy of observations related to electric field modes and their ionospheric and magnetospheric Effects

    NASA Astrophysics Data System (ADS)

    Lyons, L. R.; Gallardo-Lacourt, B.; Zou, S.; Weygand, J. M.; Nishimura, Y.; Li, W.; Gkioulidou, M.; Angelopoulos, V.; Donovan, E. F.; Ruohoniemi, J. M.; Anderson, B. J.; Shepherd, S. G.; Nishitani, N.

    2016-11-01

    The main phase of the 17 March 2013 storm had excellent coverage from ground-based instruments and from low- and high-altitude spacecraft, allowing for evaluation of the relations between major storm time phenomena that are often considered separately. The shock impact with its concurrent southward interplanetary magnetic field (IMF) immediately drove dramatic poleward expansion of the poleward boundary of the auroral oval (implying strong nightside reconnection), strong auroral activity, and strong penetrating midlatitude convection and ionospheric currents. This was followed by periods of southward IMF driving of electric fields that were at first relatively smooth as often employed in storm modeling but then became extremely bursty and structured associated with equatorward extending auroral streamers. The auroral oval did not expand much further poleward during these two latter periods, suggesting a lower overall nightside reconnection rate than that during the first period and approximate balance with dayside reconnection. Characteristics of these three modes of driving were reflected in horizontal and field-aligned currents. Equatorward expansion of the auroral oval occurred predominantly during the structured convection mode, when electric fields became extremely bursty. The period of this third mode also approximately corresponded to the time of largest equatorward motion of the ionospheric trough, of apparent transport of high total electron content (TEC) features into the auroral oval from the polar cap, and of largest earthward injection of ions and electrons into the ring current. The enhanced responses of the aurora, currents, TEC, and the ring current indicate a common driving of all these storm time features during the bursty convection mode period.

  11. An evaluation of two conducted electrical weapons using a swine comparative cardiac safety model.

    PubMed

    Dawes, Donald M; Ho, Jeffrey D; Moore, Johanna C; Laudenbach, Andrew P; Reardon, Robert F; Miner, James R

    2014-09-01

    Arrest-related deaths proximate to the use of a conducted electrical weapon (CEW) continue to generate controversy despite a better understanding of the multi-factorial nature of many of these deaths. With the rapid adoption of this technology by law enforcement, and the proliferation of companies entering the marketplace, it is important to have a method to assess the relative safety of these weapons. We had previously developed a model to assess the relative cardiac safety of CEWs. In this study, we use this model to compare the TASER X2 and the Karbon Arms MPID. Our results suggest that the TASER X2 may have an improved cardiac safety margin over the Karbon Arms MPID as determined by a smaller area of cardiac pacing on the anterior chest in our model. This model seems to offer a reproducible means of comparing the cardiac effects of CEWs.

  12. Fractional diffusion models of cardiac electrical propagation: role of structural heterogeneity in dispersion of repolarization

    PubMed Central

    Bueno-Orovio, Alfonso; Kay, David; Grau, Vicente; Rodriguez, Blanca; Burrage, Kevin

    2014-01-01

    Impulse propagation in biological tissues is known to be modulated by structural heterogeneity. In cardiac muscle, improved understanding on how this heterogeneity influences electrical spread is key to advancing our interpretation of dispersion of repolarization. We propose fractional diffusion models as a novel mathematical description of structurally heterogeneous excitable media, as a means of representing the modulation of the total electric field by the secondary electrical sources associated with tissue inhomogeneities. Our results, analysed against in vivo human recordings and experimental data of different animal species, indicate that structural heterogeneity underlies relevant characteristics of cardiac electrical propagation at tissue level. These include conduction effects on action potential (AP) morphology, the shortening of AP duration along the activation pathway and the progressive modulation by premature beats of spatial patterns of dispersion of repolarization. The proposed approach may also have important implications in other research fields involving excitable complex media. PMID:24920109

  13. Outcomes of ventricular tachycardia ablation in patients with structural heart disease: The impact of electrical storm

    PubMed Central

    Aldhoon, Bashar; Wichterle, Dan; Peichl, Petr; Čihák, Robert; Kautzner, Josef

    2017-01-01

    Aims To investigate predictors of long-term outcomes after catheter ablation (CA) for ventricular tachycardia (VT) and the impact of electrical storm (ES) prior to index ablation procedures. Methods We studied consecutive patients with structural heart disease and VT (n = 328; age: 63±12 years; 88% males; 72% ischaemic cardiomyopathy; LVEF: 32±12%) who had undergone CA. According to presenting arrhythmia at baseline, they were divided into ES (n = 93, 28%) and non-ES groups. Clinical predictors of all-cause mortality were investigated and a clinically useful risk score (SCORE) was constructed. Results During a median follow-up of 927 days (IQR: 564–1626), 67% vs. 60% of patients (p = 0.05) experienced VT recurrence in the ES vs. the non-ES group, respectively; and 41% vs. 32% patients died (p = 0.02), respectively. Five factors were independently associated with mortality: age >70 years (hazard ratio (HR): 1.6, 95% confidence interval (CI): 1.1–2.4, p = 0.01), NYHA class ≥3 (HR: 1.9, 95% CI: 1.2–2.9, p = 0.005), a serum creatinine level >1.3 mg/dL (HR: 1.6, 95% CI: 1.1–2.3, p = 0.02), LVEF ≤25% (HR: 2.4, 95% CI: 1.6–3.5, p = 0.00004), and amiodarone therapy (HR: 1.5, 95% CI: 1.0–2.2, p = 0.03). A risk SCORE ranging from 0–4 (1 point for either high-risk age, NYHA, creatinine, or LVEF) correlated with mortality. ES during index ablation independently predicted mortality only in patients with a SCORE ≤1. Conclusions Advanced LV dysfunction, older age, higher NYHA class, renal dysfunction, and amiodarone therapy, but not ES, were predictors of poor outcomes after CA for VT in the total population. However, ES did predict mortality in a low-risk sub-group of patients. PMID:28187168

  14. Changes in the cardiac muscle electric activity as a result of Coronary Artery Bypass Graft operation

    NASA Astrophysics Data System (ADS)

    Grajek, Magdalena; Krzyminiewski, Ryszard; Kalawski, Ryszard; Kulczak, Mariusz

    2008-01-01

    Many bioelectric signals have a complex internal structure that can be a rich source of information on the tissue or cell processes. The structure of such signals can be analysed in detail by applying digital methods of signal processing. Therefore, of substantial use in diagnosis of the coronary arterial disease is the method of digital enhancement of increasing signal resolution ECG (NURSE-ECG), permitting detection of temporary changes in the electric potentials in the cardiac muscle in the process of depolarisation. Thanks to the application of NURSE-ECG it has become possible to detect relatively small changes in the electric activity of particular fragments of the cardiac muscle undetectable by the standard ECG method, caused by ischemia, the effect of a drug or infarct. The aim of this study was to identify and analyse changes in the electric activity of the cardiac muscle as a result of the Coronary Artery Bypass Graft (CABG) operation. In this study the method of NURSE-ECG has been applied in order to identify and analyse changes in the electric activity of the cardiac muscle as a result of the CABG operation. In the study performed in cooperation of the Institute of Physics Adam Mickiewicz University and the Strus Hospital, Cardiac Surgery Ward, 37 patients with advanced coronary arterial disease were asked to participate. The patients were examined prior to the operation, on the day after the operation and two months after the operation and a year after the operation. The ECG recordings were subjected to a numerical procedure of resolution enhancement by a NURSE-ECG program to reveal the tentative changes in the electric potential of the cardiac muscle on its depolarisation. Results of the study have shown that the NURSE ECG method can be applied to monitor changes in the electric activity of the cardiac muscle occurring as a result of CABG operation. One the second day after the operation in the majority of patients (70%) a rapid decrease of the total

  15. Learning the Cardiac Cycle: Simultaneous Observations of Electrical and Mechanical Events.

    ERIC Educational Resources Information Center

    Kenney, Richard Alec; Frey, Mary Anne Bassett

    1980-01-01

    Described is a method for integrating electrical and mechanical events of the cardiac cycle by measuring systolic time intervals, which involves simultaneous recording of the ECG, a phonocardiogram, and the contour of the carotid pulse. Both resting and stress change data are provided as bases for class discussion. (CS)

  16. ALTERATION OF CARDIAC ELECTRICAL ACTIVITY BY WATER-LEACHABLE COMPONENTS OF RESIDUAL OIL FLY ASH (ROFA)

    EPA Science Inventory

    Alteration of cardiac electrical activity by water-leachable components
    of residual oil fly ash (ROFA)

    Desuo Wang, Yuh-Chin T. Huang*, An Xie, Ting Wang

    *Human Studies Division, NHEERL, US EPA
    104 Mason Farm Road, Chapel Hill, NC 27599
    Department of Basic ...

  17. Presentation of untreated systemic mastocytosis as recurrent, pulseless-electrical-activity cardiac arrests resistant to cardiac pacemaker.

    PubMed

    Butterfield, Joseph H; Weiler, Catherine R

    2014-01-01

    Recurrent, pulseless-electrical-activity (PEA) cardiac arrests were the novel presentation of untreated systemic mastocytosis in an 85-year-old woman who lacked cutaneous findings of mastocytosis. Despite prior implantation of a dual-chamber cardiac pacemaker 3 weeks previously for similar spells, she experienced a PEA arrest accompanied by flushing, increased urinary N-methylhistamine excretion and serum tryptase values on the day of presentation to our clinic. Bone marrow biopsy findings conducted to rule out breast cancer metastases showed 30% mast cell infiltration, aberrant expression of CD25 and a positive c-kit Asp816Val mutation. Treatment with a combination of H1 and H2 receptor blockers reduced flushing and eliminated hypotension. Maintenance medication included aspirin, cetirizine, ranitidine, montelukast, oral cromolyn sodium and an epinephrine autoinjector (as needed). At 6-month follow-up, the patient remained free of PEA arrests, flushing, or any clinical signs of mastocytosis or mast cell degranulation. PEA cardiac arrests may therefore be a presenting sign of untreated systemic mastocytosis.

  18. [Despite medication, overdrive pacing is required to stabilize the electrical storm associated with acute coronary syndrome: a case report].

    PubMed

    Umeda, Masanobu; Morimoto, Atsushi; Yokoyama, Kaori; Tateishi, Emi; Makino, Kanako; Yamamoto, Kazuo; Nakagawa, Yoko; Fukuhara, Shinya; Takase, Eiji

    2007-10-01

    A 75-year-old female complained of severe chest pain and was emergently admitted to our hospital because of anterior acute myocardial infarction. Emergent coronary angiography was performed and revealed occlusion in segment 7, so a stent was implanted. Lidocaine, carvedilol, amiodarone, magnesium, and nifekalant were administered successively because non-sustained ventricular tachycardia (NSVT) frequently appeared like an electrical storm. After nifekalant administration, QTc was significantly prolonged and torsades de pointes was induced. Overdrive pacing was performed and finally the NSVT was completely controlled. If fatal arrhythmias such as NSVT show resistance to medication, overdrive pacing should be considered to stabilize the arrhythmia associated with acute coronary syndrome.

  19. Theory and cardiac applications of electrical impedance measurements.

    PubMed

    Penney, B C

    1986-01-01

    The methodology of the two-electrode, four-electrode, and guard-ring techniques is presented following a brief history of impedance plethysmography. The theoretical basis for predicting the sampling fields for conductivity and volume changes is presented. Theoretical and experimental studies of the sampling field associated with various electrode arrays are reviewed. With this background, the use of impedance plethysmography for cardiac monitoring and diagnosis is reviewed. The basic methodology is presented and models used to interpret the signal are reviewed. Theoretical and experimental studies of what is sampled are summarized. The accuracy of impedance stroke volume estimates is evaluated by surveying the results of human studies and examining critical animal studies. The usefulness of impedance cardiography for ventricular performance evaluation is also reviewed. Additional uses for cardiopulmonary diagnosis are briefly presented.

  20. Electrical coupling of single cardiac rat myocytes to field-effect and bipolar transistors.

    PubMed

    Kind, Thomas; Issing, Matthias; Arnold, Rüdiger; Müller, Bernt

    2002-12-01

    A novel bipolar transistor for extracellular recording the electrical activity of biological cells is presented, and the electrical behavior compared with the field-effect transistor (FET). Electrical coupling is examined between single cells separated from the heart of adults rats (cardiac myocytes) and both types of transistors. To initiate a local extracellular voltage, the cells are periodically stimulated by a patch pipette in voltage clamp and current clamp mode. The local extracellular voltage is measured by the planar integrated electronic sensors: the bipolar and the FET. The small signal transistor currents correspond to the local extracellular voltage. The two types of sensor transistors used here were developed and manufactured in the laboratory of our institute. The manufacturing process and the interfaces between myocytes and transistors are described. The recordings are interpreted by way of simulation based on the point-contact model and the single cardiac myocyte model.

  1. Advanced computer techniques for inverse modeling of electric current in cardiac tissue

    SciTech Connect

    Hutchinson, S.A.; Romero, L.A.; Diegert, C.F.

    1996-08-01

    For many years, ECG`s and vector cardiograms have been the tools of choice for non-invasive diagnosis of cardiac conduction problems, such as found in reentrant tachycardia or Wolff-Parkinson-White (WPW) syndrome. Through skillful analysis of these skin-surface measurements of cardiac generated electric currents, a physician can deduce the general location of heart conduction irregularities. Using a combination of high-fidelity geometry modeling, advanced mathematical algorithms and massively parallel computing, Sandia`s approach would provide much more accurate information and thus allow the physician to pinpoint the source of an arrhythmia or abnormal conduction pathway.

  2. Prompt penetration electric fields and the extreme topside ionospheric response to the June 22-23, 2015 geomagnetic storm as seen by the Swarm constellation

    NASA Astrophysics Data System (ADS)

    Astafyeva, Elvira; Zakharenkova, Irina; Alken, Patrick

    2016-09-01

    Using data from the three Swarm satellites, we study the ionospheric response to the intense geomagnetic storm of June 22-23, 2015. With the minimum SYM-H excursion of -207 nT, this storm is so far the second strongest geomagnetic storm in the current 24th solar cycle. A specific configuration of the Swarm satellites allowed investigation of the evolution of the storm-time ionospheric alterations on the day- and the nightside quasi-simultaneously. With the development of the main phase of the storm, a significant dayside increase of the vertical total electron content (VTEC) and electron density Ne was first observed at low latitudes on the dayside. From ~22 UT of 22 June to ~1 UT of 23 June, the dayside experienced a strong negative ionospheric storm, while on the nightside an extreme enhancement of the topside VTEC occurred at mid-latitudes of the northern hemisphere. Our analysis of the equatorial electrojet variations obtained from the magnetic Swarm data indicates that the storm-time penetration electric fields were, most likely, the main driver of the observed ionospheric effects at the initial phase of the storm and at the beginning of the main phase. The dayside ionosphere first responded to the occurrence of the strong eastward equatorial electric fields. Further, penetration of westward electric fields led to gradual but strong decrease of the plasma density on the dayside in the topside ionosphere. At this stage, the disturbance dynamo could have contributed as well. On the nightside, the observed extreme enhancement of the Ne and VTEC in the northern hemisphere (i.e., the summer hemisphere) in the topside ionosphere was most likely due to the combination of the prompt penetration electric fields, disturbance dynamo and the storm-time thermospheric circulation. From ~2.8 UT, the ionospheric measurements from the three Swarm satellites detected the beginning of the second positive storm on the dayside, which was not clearly associated with electrojet

  3. Quantifying the Accuracy of Inner Magnetospheric Electric Field Descriptions With Data- Model Comparisons for All Intense Storms of Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Jazowski, M.; Ilie, R.; Thomsen, M. F.; Borovsky, J. E.

    2008-12-01

    All of the intense magnetic storms (minimum Dst value of < -100 nT) from solar cycle 23 (1996 - 2005) were simulated using the hot electron and ion drift integrator (HEIDI) model. The simulations were run using two electric field descriptions: a Kp-driven shielded Volland-Stern electric field and a self-consistent electric field calculated from the HEIDI-generated field-aligned currents. Of the 90 events, 69 had acceptable boundary condition inputs (nightside plasma data from LANL and upstream solar wind data during the main phase), and are included in the analysis. Storms were classified according to their solar wind driver and means and correlations were examined. Data-model comparisons are made against Dst* time series and dayside LANL plasma data (plasmaspheric plume, hot ion moments and fluxes). It is found, for example, with Dst* comparisons, that the self-consistent electric field simulations are, on average, more accurate than the Volland-Stern-driven simulations. This is especially true for magnetic cloud-driven storm events. For other storm driver categories, the self-consistent results are, on average, more precise than the Volland-Stern results, with less variability in the data-model comparisons from one storm to the next. Other aspects of the data-model comparisons are presented and discussed.

  4. Role of TGF-β on cardiac structural and electrical remodeling

    PubMed Central

    Ramos-Mondragón, Roberto; Galindo, Carlos A; Avila, Guillermo

    2008-01-01

    The type β transforming growth factors (TGF-βs) are involved in a number of human diseases, including heart failure and myocardial arrhythmias. In fact, during the last 20 years numerous studies have demonstrated that TGF-β affects the architecture of the heart under both normal and pathological conditions. Moreover, TGF-β signaling is currently under investigation, with the aim of discovering potential therapeutic roles in human disease. In contrast, only few studies have investigated whether TGF-β affects electrophysiological properties of the heart. This fact is surprising since electrical remodeling represents an important substrate for cardiac disease. This review discusses the potential role of TGF-β on cardiac excitation-contraction (EC) coupling, action potentials, and ion channels. We also discuss the effects of TGF-β on cardiac development and disease from structural and electrophysiological points of view. PMID:19337543

  5. Cardiac mechano-electric coupling research: fifty years of progress and scientific innovation.

    PubMed

    Quinn, T Alexander; Kohl, Peter; Ravens, Ursula

    2014-08-01

    With its conceptualisation nearly fifty years ago, cardiac mechano-electric coupling (MEC) has developed from a collection of anecdotal reports into a field of research that - in spite of early scepticism - is now an accepted part of cardiac structure-function considerations. Throughout this development, MEC studies have been both driver and beneficiary of technological innovation: from sharp electrode recordings for the study of in situ cell responses to cell isolation and patch clamp; from early approaches to mechanical stimulation of tissue using photographic diaphragms to modern force-length feedback systems for isolated cells; and from strain gauge force recordings to genetically encodes stress probes. While much is now known about subcellular contributors to cardiac MEC, including stretch-activated ion channels and mechanical modulation of cell calcium handling, their integration at higher levels of structural complexity, and the generation of clinically-translatable knowledge, have remained challenging. This short review provides a brief summary of past achievements, current activities, and potentially rewarding future directions of cardiac MEC research. We highlight challenges and opportunities on the way to an integrated understanding of how external and intrinsic mechanical factors affect the heartbeat in health and disease, and how such understanding may improve the ways in which we prevent and/or treat cardiac pathology.

  6. Monitoring of regional lung ventilation using electrical impedance tomography after cardiac surgery in infants and children.

    PubMed

    Krause, Ulrich; Becker, Kristin; Hahn, Günter; Dittmar, Jörg; Ruschewski, Wolfgang; Paul, Thomas

    2014-08-01

    Electrical impedance tomography (EIT) is a noninvasive method to monitor regional lung ventilation in infants and children without using radiation. The objective of this prospective study was to determine the value of EIT as an additional monitoring tool to assess regional lung ventilation after pediatric cardiac surgery for congenital heart disease in infants and children. EIT monitoring was performed in a prospective study comprising 30 pediatric patients who were mechanically ventilated after cardiac surgery. Data were analyzed off-line with respect to regional lung ventilation in different clinical situations. EIT data were correlated with respirator settings and arterial carbon dioxide (CO2) partial pressure in the blood. In 29 of 30 patients, regional ventilation of the lung could sufficiently and reliably be monitored by means of EIT. The effects of the transition from mechanical ventilation to spontaneous breathing after extubation on regional lung ventilation were studied. After extubation, a significant decrease of relative impedance changes was evident. In addition, a negative correlation of arterial CO2 partial pressure and relative impedance changes could be shown. EIT was sufficient to discriminate differences of regional lung ventilation in children and adolescents after cardiac surgery. EIT reliably provided additional information on regional lung ventilation in children after cardiac surgery. Neither chest tubes nor pacemaker wires nor the intensive care unit environment interfered with the application of EIT. EIT therefore may be used as an additional real-time monitoring tool in pediatric cardiac intensive care because it is noninvasive.

  7. Wave Science with the Electric and Magnetic Field Instrument Suite with Integrated Science (EMFISIS) on the Radiation Belt Storm Probes

    NASA Astrophysics Data System (ADS)

    Bounds, S. R.; Kletzing, C. A.; Kurth, W. S.; Acuna, M. H.; Torbert, R. B.; Thorne, R.; Jordanova, V.; Smith, C.; Santolik, O.; Pfaff, R.; Rpwlamd, D.; Hospodarsky, G.; Baumjohann, W.; Nakamura, R.; Puhl-Quinn, P.

    2008-12-01

    The physics of the creation and loss of radiation belt particles is intimately connected to the electric and magnetic fields of waves which mediate these processes. A large range of field regimes are involved in this physics from ring current magnetic fields to microscopic kinetic interactions such as whistler-mode chorus waves with energetic electrons. To measure these key field interactions, NASA has selected the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Radiation Belt Storm Probes (RBSP). EMFISIS is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer and measures AC electric and magnetic fields from 10 Hz to 400 kHz. The broad frequency range of the Waves instrument enables the identification of resonances and cutoffs from Waves to achieve high cadence, accurate plasma density measurements that are essential to RBSP theory and modeling efforts. In combination with the selected double probe electric field and particle investigations on RBSP, EMFISIS will provide the essential measurements necessary to open the frontier of predictive capability for the Earth's highly variable radiation belts. We discuss of the key scientific goals of the EMFISIS investigation with particular attention to the wave physics of the radiation belts.

  8. A cardiac electrical activity model based on a cellular automata system in comparison with neural network model.

    PubMed

    Khan, Muhammad Sadiq Ali; Yousuf, Sidrah

    2016-03-01

    Cardiac Electrical Activity is commonly distributed into three dimensions of Cardiac Tissue (Myocardium) and evolves with duration of time. The indicator of heart diseases can occur randomly at any time of a day. Heart rate, conduction and each electrical activity during cardiac cycle should be monitor non-invasively for the assessment of "Action Potential" (regular) and "Arrhythmia" (irregular) rhythms. Many heart diseases can easily be examined through Automata model like Cellular Automata concepts. This paper deals with the different states of cardiac rhythms using cellular automata with the comparison of neural network also provides fast and highly effective stimulation for the contraction of cardiac muscles on the Atria in the result of genesis of electrical spark or wave. The specific formulated model named as "States of automaton Proposed Model for CEA (Cardiac Electrical Activity)" by using Cellular Automata Methodology is commonly shows the three states of cardiac tissues conduction phenomena (i) Resting (Relax and Excitable state), (ii) ARP (Excited but Absolutely refractory Phase i.e. Excited but not able to excite neighboring cells) (iii) RRP (Excited but Relatively Refractory Phase i.e. Excited and able to excite neighboring cells). The result indicates most efficient modeling with few burden of computation and it is Action Potential during the pumping of blood in cardiac cycle.

  9. Risk of electromagnetic interference induced by dental equipment on cardiac implantable electrical devices.

    PubMed

    Miranda-Rius, Jaume; Lahor-Soler, Eduard; Brunet-Llobet, Lluís; Sabaté de la Cruz, Xavier

    2016-12-01

    Patients with cardiac implantable electrical devices should take special precautions when exposed to electromagnetic fields. Proximity to equipment used in clinical dentistry may cause interference. This study evaluated in vitro the risks associated with different types/makes of cardiac devices and types of dental equipment. Six electronic dental tools were tested on three implantable cardioverter defibrillators and three pacemakers made by different manufacturers. Overall, the risk of interference with the pacemakers was 37% lower than with the implantable cardioverter defibrillators. Regarding the types/makes of cardiac devices analysed, that from Boston Scientific had a five-fold greater risk of interference than did that from Biotronik [prevalence ratio (PR) = 5.58]; there was no difference between that from Biotronik and that from Medtronic. Among the dental equipment, the electric pulp tester had the greatest risk of inducing interference and therefore this device was used as the benchmark. The electronic apex locator (PR = 0.29), Periotest M (PR = 0.47), and the ultrasonic dental scaler (PR = 0.59) were less likely to induce interference than the electric pulp tester. The risk was lowest with the electronic apex locator. Pacemakers presented a lower risk of light to moderate interference (PR = 0.63). However, the risk of severe electromagnetic interference was 3.5 times higher with pacemakers than with implantable cardioverter defibrillators (PR = 3.47).

  10. Unpinning of rotating spiral waves in cardiac tissues by circularly polarized electric fields

    NASA Astrophysics Data System (ADS)

    Feng, Xia; Gao, Xiang; Pan, De-Bei; Li, Bing-Wei; Zhang, Hong

    2014-04-01

    Spiral waves anchored to obstacles in cardiac tissues may cause lethal arrhythmia. To unpin these anchored spirals, comparing to high-voltage side-effect traditional therapies, wave emission from heterogeneities (WEH) induced by the uniform electric field (UEF) has provided a low-voltage alternative. Here we provide a new approach using WEH induced by the circularly polarized electric field (CPEF), which has higher success rate and larger application scope than UEF, even with a lower voltage. And we also study the distribution of the membrane potential near an obstacle induced by CPEF to analyze its mechanism of unpinning. We hope this promising approach may provide a better alternative to terminate arrhythmia.

  11. Cardiac troponin I: A potent biomarker for myocardial damage assessment following high voltage electric burn

    PubMed Central

    Bose, Arindam; Chhabra, Chandra B.; Chamania, Shobha; Hemvani, Nanda; Chitnis, Dhananjay S.

    2016-01-01

    Myocardial infarction (MI) following high voltage electric burn is very rare, and its pathogenesis remains controversial. Electrical burns represent only 4% of all burns. Hence, clinical managements have taken a slow pace in developing. The recent guidelines laid down by the cardiology societies include cardiac troponin I (cTnI) as the gold standard marker for the assessment of myocardial damage assessment. Two patients were admitted to our hospital at the different time with the same kind of high voltage electric burn. Both patients had complained with chest discomfort during admission, and cardiac parameter assessment was done for both the patients. cTnI was also measured for both patients, and marked increase in the values was seen within 5 h of onset of myocardial damage and got into normal range within 72 h. Myocardial damage following electric burn needs to be suspected and assessed as early as possible. Hence, cTnI should be the valuable tool to detect the severity of myocardial damage incurred in the electric burn cases. PMID:28216824

  12. Atmospheric electrical modeling in support of the NASA F106 Storm Hazards Project

    NASA Technical Reports Server (NTRS)

    Helsdon, J. H.

    1986-01-01

    With the use of composite (non-metallic) and microelectronics becoming more prevalent in the construction of both military and commercial aircraft, the control systems have become more susceptible to damage or failure from electromagnetic transients. One source of such transients is the lightning discharge. In order to study the effects of the lightning discharge on the vital components of an aircraft, NASA Langley Research Center has undertaken a Storm Hazards Program in which a specially instrumented F106B jet aircraft is flown into active thunderstorms with the intention of being struck by lightning. One of the specific purposes of the program is to quantify the environmental conditions which are conductive to aircraft lightning strikes.

  13. Comparison of Transcutaneous Electrical Nerve Stimulation and Parasternal Block for Postoperative Pain Management after Cardiac Surgery.

    PubMed

    Ozturk, Nilgun Kavrut; Baki, Elif Dogan; Kavakli, Ali Sait; Sahin, Ayca Sultan; Ayoglu, Raif Umut; Karaveli, Arzu; Emmiler, Mustafa; Inanoglu, Kerem; Karsli, Bilge

    2016-01-01

    Background. Parasternal block and transcutaneous electrical nerve stimulation (TENS) have been demonstrated to produce effective analgesia and reduce postoperative opioid requirements in patients undergoing cardiac surgery. Objectives. To compare the effectiveness of TENS and parasternal block on early postoperative pain after cardiac surgery. Methods. One hundred twenty patients undergoing cardiac surgery were enrolled in the present randomized, controlled prospective study. Patients were assigned to three treatment groups: parasternal block, intermittent TENS application, or a control group. Results. Pain scores recorded 4 h, 5 h, 6 h, 7 h, and 8 h postoperatively were lower in the parasternal block group than in the TENS and control groups. Total morphine consumption was also lower in the parasternal block group than in the TENS and control groups. It was also significantly lower in the TENS group than in the control group. There were no statistical differences among the groups regarding the extubation time, rescue analgesic medication, length of intensive care unit stay, or length of hospital stay. Conclusions. Parasternal block was more effective than TENS in the management of early postoperative pain and the reduction of opioid requirements in patients who underwent cardiac surgery through median sternotomy. This trial is registered with Clinicaltrials.gov number NCT02725229.

  14. Myocardial scaffold-based cardiac tissue engineering: application of coordinated mechanical and electrical stimulations.

    PubMed

    Wang, Bo; Wang, Guangjun; To, Filip; Butler, J Ryan; Claude, Andrew; McLaughlin, Ronald M; Williams, Lakiesha N; de Jongh Curry, Amy L; Liao, Jun

    2013-09-03

    Recently, we developed an optimal decellularization protocol to generate 3D porcine myocardial scaffolds, which preserve the natural extracellular matrix structure, mechanical anisotropy, and vasculature templates and also show good cell recellularization and differentiation potential. In this study, a multistimulation bioreactor was built to provide coordinated mechanical and electrical stimulation for facilitating stem cell differentiation and cardiac construct development. The acellular myocardial scaffolds were seeded with mesenchymal stem cells (10(6) cells/mL) by needle injection and subjected to 5-azacytidine treatment (3 μmol/L, 24 h) and various bioreactor conditioning protocols. We found that after 2 days of culturing with mechanical (20% strain) and electrical stimulation (5 V, 1 Hz), high cell density and good cell viability were observed in the reseeded scaffold. Immunofluorescence staining demonstrated that the differentiated cells showed a cardiomyocyte-like phenotype by expressing sarcomeric α-actinin, myosin heavy chain, cardiac troponin T, connexin-43, and N-cadherin. Biaxial mechanical testing demonstrated that positive tissue remodeling took place after 2 days of bioreactor conditioning (20% strain + 5 V, 1 Hz); passive mechanical properties of the 2 day and 4 day tissue constructs were comparable to those of the tissue constructs produced by stirring reseeding followed by 2 weeks of static culturing, implying the effectiveness and efficiency of the coordinated simulations in promoting tissue remodeling. In short, the synergistic stimulations might be beneficial not only for the quality of cardiac construct development but also for patients by reducing the waiting time in future clinical scenarios.

  15. Myocardial Scaffold-based Cardiac Tissue Engineering: Application of Coordinated Mechanical and Electrical Stimulations

    PubMed Central

    Wang, Bo; Wang, Guangjun; To, Filip; Butler, J. Ryan; Claude, Andrew; McLaughlin, Ronald M.; Williams, Lakiesha N.; de Jongh Curry, Amy L.; Liao, Jun

    2013-01-01

    Recently, we have developed an optimal decellularization protocol to generate 3D porcine myocardial scaffolds, which preserved natural extracellular matrix structure, mechanical anisotropy, and vasculature templates, and also showed good cell recellularization and differentiation potential. In this study, a multi-stimulation bioreactor was built to provide coordinated mechanical and electrical stimulations for facilitating stem cell differentiation and cardiac construct development. The acellular myocardial scaffolds were seeded with mesenchymal stem cells (106 cells/ml) by needle injection and subjected to 5-azacytidine treatment (3 μmol/L, 24 h) and various bioreactor conditioning protocols. We found that, after 2-day culture with mechanical (20% strain) and electrical stimulation (5 V, 1 Hz), high cell density and good cell viability were observed in the reseeded scaffold. Immunofluorescence staining demonstrated that the differentiated cells showed cardiomyocyte-like phenotype, by expressing sarcomeric α-actinin, myosin heavy chain, cardiac troponin T, connexin-43, and N-cadherin. Biaxial mechanical testing demonstrated that positive tissue remodeling took place after 2-day bioreactor conditioning (20% strain + 5 V, 1 Hz); passive mechanical properties of the 2-day and 4-day tissue constructs were comparable to the tissue constructs produced by stirring reseeding followed by 2-week static culture, implying the effectiveness and efficiency of the coordinated simulations in promoting tissue remodeling. In short, the synergistic stimulations might be beneficial not only for the quality of cardiac construct development, but also for patients by reducing the waiting time in future clinical scenarios. PMID:23923967

  16. Coordinating Electrical Activity of the Heart: Ankyrin Polypeptides in Human Cardiac Disease

    PubMed Central

    Curran, Jerry; Mohler, Peter J

    2011-01-01

    Introduction Over the past ten years, ankyrin polypeptides have emerged as critical players in cardiac excitation-contraction coupling. Once thought to solely play only a structural role, loss-of-function variants in genes encoding ankyrin polypeptides have highlighted how this protein mediates the proper subcellular localization of the various electrical components of the excitation-contraction coupling machinery. A large body of evidence has revealed how the disruption of this localization is the primary cause of various cardiomyopathies, ranging from long QT syndrome 4, to sinus node disease, to more common forms of arrhythmias. Areas Covered This review details the varied roles that ankyrin polypeptides play in excitation-contraction coupling in the heart and the development of ankyrin-specific cardiomyopathies. It will further discuss how ankyrin polypeptides may be involved in structural and electrical remodeling of the heart, post-myocardial infarct. Attention is given to how ankyrin interactions with membrane bound ion channels may regulate these channels’ response to stimuli. Special attention is given to exciting new data, which may offer the potential for unique therapies, for not only combating heart disease, but which also holds promise for wider applications to various disease states. Expert Opinion The ankyrin family of adapter proteins is emerging as an intimate player in cardiac excitation-contraction coupling. Until recently, these proteins have gone largely unappreciated for their importance in proper cardiac function. New insights into how these proteins function within the heart are offering potentially new avenues for therapies against cardiomyopathy. PMID:21457127

  17. Development and characterization of novel electrically conductive PANI-PGS composites for cardiac tissue engineering applications.

    PubMed

    Qazi, Taimoor H; Rai, Ranjana; Dippold, Dirk; Roether, Judith E; Schubert, Dirk W; Rosellini, Elisabetta; Barbani, Niccoletta; Boccaccini, Aldo R

    2014-06-01

    Cardiovascular diseases, especially myocardial infarction, are the leading cause of morbidity and mortality in the world, also resulting in huge economic burdens on national economies. A cardiac patch strategy aims at regenerating an infarcted heart by providing healthy functional cells to the injured region via a carrier substrate, and providing mechanical support, thereby preventing deleterious ventricular remodeling. In the present work, polyaniline (PANI) was doped with camphorsulfonic acid and blended with poly(glycerol-sebacate) at ratios of 10, 20 and 30vol.% PANI content to produce electrically conductive composite cardiac patches via the solvent casting method. The composites were characterized in terms of their electrical, mechanical and physicochemical properties. The in vitro biodegradability of the composites was also evaluated. Electrical conductivity increased from 0Scm(-1) for pure PGS to 0.018Scm(-1) for 30vol.% PANI-PGS samples. Moreover, the conductivities were preserved for at least 100h post fabrication. Tensile tests revealed an improvement in the elastic modulus, tensile strength and elasticity with increasing PANI content. The degradation products caused a local drop in pH, which was higher in all composite samples compared with pure PGS, hinting at a buffering effect due to the presence of PANI. Finally, the cytocompatibility of the composites was confirmed when C2C12 cells attached and proliferated on samples with varying PANI content. Furthermore, leaching of acid dopants from the developed composites did not have any deleterious effect on the viability of C2C12 cells. Taken together, these results confirm the potential of PANI-PGS composites for use as substrates to modulate cellular behavior via electrical stimulation, and as biocompatible scaffolds for cardiac tissue engineering applications.

  18. Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology.

    PubMed

    Tse, Gary; Lai, Eric Tsz Him; Yeo, Jie Ming; Tse, Vivian; Wong, Sunny Hei

    2016-01-01

    The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field.

  19. Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology

    PubMed Central

    Tse, Gary; Lai, Eric Tsz Him; Yeo, Jie Ming; Tse, Vivian; Wong, Sunny Hei

    2016-01-01

    The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field. PMID:27303305

  20. The Electric and Magnetic Field Instrument Suite with Integrated Science (EMFISIS) on the Radiation Belt Storm Probes

    NASA Astrophysics Data System (ADS)

    Kletzing, C. A.; Kurth, W.; Acuna, M.; Torbert, R.; Thorne, R.; Jordanova, V.; Bounds, S.; Smith, C.; Santolik, O.; Pfaff, R.; Rowland, D.; Hospodarsky, G.; Baumjohann, W.; Nakamura, R.; Puhl-Quinn, P.

    2006-12-01

    The physics of the creation and loss of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field dynamics and time scales are involved in this physics from ring current magnetic fields to microscopic kinetic interactions such as whistler-mode chorus waves with energetic electrons. To measure these key field interactions, NASA has selected the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Radiation Belt Storm Probes (RBSP). EMFISIS is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer and measures AC electric and magnetic fields from 10 Hz to MHz frequencies. The broad frequency range of the Waves instrument enables the identification of resonances and cutoffs from Waves to achieve high cadence, accurate plasma density measurements that are essential to RBSP theory and modeling efforts. The instruments are integrated through a Central Data Processor Unit (CDPU) which provides for flexible instrument operations in both burst and survey telemetry modes that can be optimized to address the specific physics of the many radiation belt processes. The EMFISIS multi-institution team comprises a group of knowledgeable space physics investigators, both experimental and theoretical, with the requisite capability, desire, and experience to accomplish the goals of the RBSP mission to further our nation's space weather capability. In combination with the selected double probe electric field and particle investigations on RBSP, EMFISIS will provide the essential measurements necessary to open the frontier of predictive capability for the Earth's highly variable radiation belts.

  1. The Electric and Magnetic Field Instrument Suite with Integrated Science (EMFISIS) on the Radiation Belt Storm Probes

    NASA Astrophysics Data System (ADS)

    Kletzing, Craig

    The physics of the creation and loss of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field regimes are involved in this physics from ring current magnetic fields to microscopic kinetic interactions such as whistler-mode chorus waves with energetic electrons. To measure these key field interactions, NASA has selected the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Radiation Belt Storm Probes (RBSP). EMFISIS is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer and measures AC electric and magnetic fields from 10 Hz to 400 kHz. The broad frequency range of the Waves instrument enables the identification of resonances and cutoffs from Waves to achieve high cadence, accurate plasma density measurements that are essential to RBSP theory and modeling efforts. The instruments are integrated through a Central Data Processor Unit (CDPU) which provides for flexible instrument operations in both burst and survey telemetry modes that can be optimized to address the specific physics of the many radiation belt processes. The EMFISIS multi-institution team comprises a group of knowledgeable space physics investigators, both experimental and theoretical with the requisite capability, desire, and experience to accomplish the goals of the RBSP mission to further space weather capability. In combination with the selected double probe electric field and particle investigations on RBSP, EMFISIS will provide the essential measurements necessary to open the frontier of predictive capability for the Earth's highly variable radiation belts.

  2. A guide to modelling cardiac electrical activity in anatomically detailed ventricles.

    PubMed

    Clayton, R H; Panfilov, A V

    2008-01-01

    One of the most recent trends in cardiac electrophysiology is the development of integrative anatomically accurate models of the heart, which include description of cardiac activity from sub-cellular and cellular level to the level of the whole organ. In order to construct this type of model, a researcher needs to collect a wide range of information from books and journal articles on various aspects of biology, physiology, electrophysiology, numerical mathematics and computer programming. The aim of this methodological article is to survey recent developments in integrative modelling of electrical activity in the ventricles of the heart, and to provide a practical guide to the resources and tools that are available for work in this exciting and challenging area.

  3. The Electric Field Wave Instrument on the Radiation Belt Storm Probe Mission

    NASA Astrophysics Data System (ADS)

    Wygant, J. R.; Cattell, C. A.; Dombeck, J.; Bonnell, J.; Mozer, F.; Bale, S.; Chaston, C.; Ergun, B.; Baker, D.; Li, X.; Hudson, M. K.; Strangeway, R.; Alpert, J.; Brautigam, D.; Mann, I.; Foster, J.

    2006-12-01

    The purpose of the Electric Field-Wave Instrument on the two RBSP spacecraft is to investigate the role of plasma structures and waves in the physical processes responsible for the acceleration, transport, and loss of energetic particles in the inner magnetosphere of the Earth. Some of these processes include: prompt acceleration induced by powerful interplanetary shocks, acceleration by the large scale convection electric field, abrupt energization by intense substorm injection fronts propagating in from the tail, coherent and stochastic radial transport by large scale MHD fluctuations, multi-step local energization and cattering by whistler waves, and scattering and energization by kinetic Alfven waves, ion cycltron waves, and other small scale waves and structures. In order to understand the role of these processes in accelerating particles, the EFW instrument measures the three dimensional electric field from dc to greater than 500 kHz. The spin plane electric field vector is obtained from spherical sensors at the ends of two pair of orthogonal booms with tip-to- tip separations of 80 and 100 m. The spin axis measurement is obtained by opposed stacer booms with a tip- to-tip separation of 12 meters or greater. The electric field below 12 Hz is telemetered continuously while higher time resolution is obtained from a programmable burst memory with a maximum sampling rate for six quantities of greater 30,000 samples/s each. DC magnetic fields from the fluxgate magnetometer and wave magnetic fields from the search coil, both associated with the University of Iowa Instrument are input into the EFW instrument for processing in the burst memory and in the Digital Signal Processing Board (DSP). The DSP provides wave spectra and cross spectra of electric and magnetic field data over the frequency range between 50 Hz and 10 kHz with a typical cadence of once per 12 seconds with a maximum rate of ~ 1 Hz in order to provide continuous information on wave properties

  4. Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity

    NASA Astrophysics Data System (ADS)

    Fenton, Flavio H.; Cherry, Elizabeth M.; Hastings, Harold M.; Evans, Steven J.

    2002-09-01

    It has become widely accepted that the most dangerous cardiac arrhythmias are due to reentrant waves, i.e., electrical wave(s) that recirculate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, have made it extremely difficult to pinpoint the detailed dynamics of these life-threatening reentrant arrhythmias. A simplified ionic model of the cardiac action potential (AP), which can be fitted to a wide variety of experimentally and numerically obtained mesoscopic characteristics of cardiac tissue such as AP shape and restitution of AP duration and conduction velocity, is used to explain many different mechanisms of spiral wave breakup which in principle can occur in cardiac tissue. Some, but not all, of these mechanisms have been observed before using other models; therefore, the purpose of this paper is to demonstrate them using just one framework model and to explain the different parameter regimes or physiological properties necessary for each mechanism (such as high or low excitability, corresponding to normal or ischemic tissue, spiral tip trajectory types, and tissue structures such as rotational anisotropy and periodic boundary conditions). Each mechanism is compared with data from other ionic models or experiments to illustrate that they are not model-specific phenomena. Movies showing all the breakup mechanisms are available at http://arrhythmia.hofstra.edu/breakup and at ftp://ftp.aip.org/epaps/chaos/E-CHAOEH-12-039203/ INDEX.html. The fact that many different breakup mechanisms exist has important implications for antiarrhythmic drug design and for comparisons of fibrillation experiments using different species, electromechanical uncoupling drugs, and initiation protocols.

  5. The Electric Fields and Waves Instrument on the Radiation Belt Storm Probe Spacecraft

    NASA Astrophysics Data System (ADS)

    Wygant, John

    The purpose of the Electric Field-Wave (EFW) Instrument on the two RBSP spacecraft is to investigate the role of electric field structures and waves in the physical processes responsible for the acceleration, transport, and loss of energetic particles in the inner magnetosphere of the Earth. The RBSP spacecraft apogee will be at about 5.8 Re near the equatorial plane. Perigee will be at about 400 kms altitude. Some of processes that will be investigated by the RBSP-EFW instrument include: prompt acceleration induced by powerful interplanetary shocks, acceleration by the large scale convection electric field, abrupt energization by intense substorm injection fronts propagating in from the tail, coherent and stochastic radial transport by large scale MHD fluctuations, and multi-step local energization and loss by whistler waves. In order to understand the role of these processes in accelerating particles, the EFW instrument measures the three dimensional electric field and cold plasma density estimates from the spacecraft potential all over a frequency range from dc to ˜500 kHz. Measurements from the spatially separated spacecraft will provide information on azimuthal and radial spatial scales and propagation velocities of large scale structures. The spin plane electric field vector is obtained from spherical sensors at the ends of two pair of orthogonal booms with tip to tip separations of 80 and 100 m. The spin axis measurement is obtained from a pair of stace booms with a tip to tip separation of ˜12 meters. The electric field below 12 Hz is telemetered continuously while higher time resolution is obtained from a programmable burst memory with a maximum sampling rate for six quantities of ˜ 30,000 samples/s. High time resolution data includes interferometric timing measurements between individual probe at the ends of the booms which provide information on small scale structures and phase velocities. DC magnetic fields from the fluxgate magnetometer and wave

  6. Duskside enhancement of equatorial zonal electric field response to convection electric fields during the St. Patrick's Day storm on 17 March 2015

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Yokoyama, T.; Otsuka, Y.; Shiokawa, K.; Sripathi, S.; Veenadhari, B.; Heelis, R.; Ajith, K. K.; Gowtam, V. S.; Gurubaran, S.; Supnithi, P.; Le Huy, M.

    2016-01-01

    The equatorial zonal electric field responses to prompt penetration of eastward convection electric fields (PPEF) were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 March 2015. At dusk sector (Indian longitudes), a rapid uplift of equatorial F layer to >550 km and development of intense equatorial plasma bubbles (EPBs) were observed. These EPBs were found to extend up to 27.13°N and 25.98°S magnetic dip latitudes indicating their altitude development to ~1670 km at apex. In contrast, at few degrees east in the premidnight sector (Thailand-Indonesian longitudes), no significant height rise and/or EPB activity has been observed. The eastward electric field perturbations due to PPEF are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo (IDD) fields, whereas they were mostly counter balanced by the IDD fields in the premidnight sector. In situ observations from SWARM-A and SWARM-C and Communication/Navigation Outage Forecasting System satellites detected a large plasma density depletion near Indian equatorial region due to large electrodynamic uplift of F layer to higher than satellite altitudes. Further, this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator. This study brings out the significantly enhanced equatorial zonal electric field in response to PPEF that is uniquely confined to dusk sector. The responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field Bz.

  7. Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering.

    PubMed

    Baei, Payam; Jalili-Firoozinezhad, Sasan; Rajabi-Zeleti, Sareh; Tafazzoli-Shadpour, Mohammad; Baharvand, Hossein; Aghdami, Nasser

    2016-06-01

    Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14 days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues.

  8. A coordinated study of a storm system over the South American continent. 1. Weather information and quasi-DC stratospheric electric field data

    NASA Astrophysics Data System (ADS)

    Pinto, O.; Pinto, I. R. C. A.; Gin, R. B. B.; Mendes, O.

    1992-11-01

    This paper reports on a coordinated campaign conducted in Brazil, December 13, 1989, to study the electrical signatures associated with a large storm system over the South American continent. Inside the storm, large convective cells developed extending up to the tropopause, as revealed from meteorological balloon soundings. Quasi-DC vertical electric field and temperature were measured by zero-pressure balloon-borne payload launched from Cachoeira Paulista, Brazil. The data were supported by radar and GOES satellite observations, as well as by a lightning position and tracking system (LPATS). The analysis of infrared imagery supports the general tendency for lightning strikes to be near to but not exactly under the coldest cloud tops. In turn, the radar maps located the strikes near to but outside of the most intense areas of precipitation (reflectivity levels above 40 dBz). The balloon altitude and stratospheric temperature show significant variations in association with the storm. The quasi-DC vertical electric field remained almost during the whole flight in a reversed direction relative to the usual fair weather downward orientation with values as large as 4 V/m. A simple calculation based on a static dipole model of electrical cloud structure gives charges of some tens of coulombs. In contrast with most electric field measurements in other regions, no indication of an intensification of the vertical field in the downward fair weather orientation was observed. This fact is in agreement with past observations in the South American region and seems to be related to a particular type of storm that would occur with more frequency in this region. If so, such a difference may have an important role in the global atmospheric electrical circuit, considering that South America is believed to give a significant current contribution to the global circuit.

  9. The impact of geomagnetic storms on the US electric power grid

    NASA Astrophysics Data System (ADS)

    Schrijver, C.; Mitchell, S.; Title, A. M.

    2012-12-01

    Large solar explosions are responsible for space weather that can impact technological infrastructure on and around Earth. We study the impacts of geomagnetic activity on the U.S. electric power grid for the period from 1992 through 2010. We find, with more than 3-sigma significance, that approximately 4% of the disturbances in the U.S. power grid reported to the U.S. Department of Energy are attributable to geomagnetic activity. The combination of our results with an economic assessment study by the electric power industry suggests that the average cost to the U.S. economy of non-catastrophic grid disturbances in which space weather conditions are a contributing factor exceeds $3 billion per year. The magnitude of this apparent economic impact warrants extensive follow-up studies to validate, understand, and mitigate against the weak but significant contribution of space weather in power grid disturbances.

  10. The link between abnormal calcium handling and electrical instability in acquired long QT syndrome--Does calcium precipitate arrhythmic storms?

    PubMed

    Němec, Jan; Kim, Jong J; Salama, Guy

    2016-01-01

    Release of Ca(2+) ions from sarcoplasmic reticulum (SR) into myocyte cytoplasm and their binding to troponin C is the final signal form myocardial contraction. Synchronous contraction of ventricular myocytes is necessary for efficient cardiac pumping function. This requires both shuttling of Ca(2+) between SR and cytoplasm in individual myocytes, and organ-level synchronization of this process by means of electrical coupling among ventricular myocytes. Abnormal Ca(2+) release from SR causes arrhythmias in the setting of CPVT (catecholaminergic polymorphic ventricular tachycardia) and digoxin toxicity. Recent optical mapping data indicate that abnormal Ca(2+) handling causes arrhythmias in models of both repolarization impairment and profound bradycardia. The mechanisms involve dynamic spatial heterogeneity of myocardial Ca(2+) handling preceding arrhythmia onset, cell-synchronous systolic secondary Ca(2+) elevation (SSCE), as well as more complex abnormalities of intracellular Ca(2+) handling detected by subcellular optical mapping in Langendorff-perfused hearts. The regional heterogeneities in Ca(2+) handling cause action potential (AP) heterogeneities through sodium-calcium exchange (NCX) activation and eventually overwhelm electrical coupling of the tissue. Divergent Ca(2+) dynamics among different myocardial regions leads to temporal instability of AP duration and - on the patient level - in T wave lability. Although T-wave alternans has been linked to cardiac arrhythmias, non-alternans lability is observed in pre-clinical models of the long QT syndrome (LQTS) and CPVT, and in LQTS patients. Analysis of T wave lability may provide a real-time window on the abnormal Ca(2+) dynamics causing specific arrhythmias such as Torsade de Pointes (TdP).

  11. Capacity of dental equipment to interfere with cardiac implantable electrical devices.

    PubMed

    Lahor-Soler, Eduard; Miranda-Rius, Jaume; Brunet-Llobet, Lluís; Sabaté de la Cruz, Xavier

    2015-06-01

    Patients with cardiac implantable electrical devices should take precautions when exposed to electromagnetic fields. Possible interference as a result of proximity to electromagnets or electricity flow from electronic tools employed in clinical odontology remains controversial. The objective of this study was to examine in vitro the capacity of dental equipment to provoke electromagnetic interference in pacemakers and implantable cardioverter defibrillators. Six electronic dental instruments were tested on three implantable cardioverter defibrillators and three pacemakers from different manufacturers. A simulator model, submerged in physiological saline, with elements that reproduced life-size anatomic structures was used. The instruments were analyzed at differing distances and for different time periods of application. The dental instruments studied displayed significant differences in their capacity to trigger electromagnetic interference. Significant differences in the quantity of registered interference were observed with respect to the variables manufacturer, type of cardiac implant, and application distance but not with the variable time of application. The electronic dental equipment tested at a clinical application distance (20 cm) provoked only slight interference in the pacemakers and implantable cardioverter defibrillators employed, irrespective of manufacturer.

  12. Cardiac tissue structure. Electric field interactions in polarizing the heart: 3D computer models and applications

    NASA Astrophysics Data System (ADS)

    Entcheva, Emilia

    1998-11-01

    The goal of this research is to investigate the interactions between the cardiac tissue structure and applied electric fields in producing complex polarization patterns. It is hypothesized that the response of the heart in the conditions of strong electric shocks, as those applied in defibrillation, is dominated by mechanisms involving the cardiac muscle structure perceived as a continuum. Analysis is carried out in three-dimensional models of the heart with detailed fiber architecture. Shock-induced transmembrane potentials are calculated using the bidomain model in its finite element implementation. The major new findings of this study can be summarized as follows: (1) The mechanisms of polarization due to cardiac fiber curvature and fiber rotation are elucidated in three-dimensional ellipsoidal hearts of variable geometry; (2) Results are presented showing that the axis of stimulation and the polarization axis on a whole heart level might differ significantly due to geometric and anisotropic factors; (3) Virtual electrode patterns are demonstrated numerically inside the ventricular wall in internal defibrillation conditions. The role of the tissue-bath interface in shaping the shock-induced polarization is revealed; (4) The generation of 3D phase singularity scrolls by shock-induced intramural virtual electrode patterns is proposed as evidence for a possible new mechanism for the failure to defibrillate. The results of this study emphasize the role of unequal anisotropy in the intra- and extracellular domains, as well as the salient fiber architecture characteristics, such as curvature and transmural rotation, in polarizing the myocardium. Experimental support of the above findings was actively sought and found in recent optical mapping studies using voltage-sensitive dyes. If validated in vivo, these findings would significantly enrich the prevailing concepts about the mechanisms of stimulation and defibrillation of the heart.

  13. Modeling storm-time electrodynamics of the low-latitude ionosphere thermosphere system: Can long lasting disturbance electric fields be accounted for?

    NASA Astrophysics Data System (ADS)

    Maruyama, Naomi; Sazykin, Stanislav; Spiro, Robert W.; Anderson, David; Anghel, Adela; Wolf, Richard A.; Toffoletto, Frank R.; Fuller-Rowell, Timothy J.; Codrescu, Mihail V.; Richmond, Arthur D.; Millward, George H.

    2007-07-01

    Storm-time ionospheric disturbance electric fields are studied for two large geomagnetic storms, March 31, 2001 and April 17 18, 2002, by comparing low-latitude observations of ionospheric plasma drifts with results from numerical simulations based on a combination of first-principles models. The simulation machinery combines the Rice convection model (RCM), used to calculate inner magnetospheric electric fields, and the coupled thermosphere ionosphere plasmasphere electrodynamics (CTIPe) model, driven, in part, by RCM-computed electric fields. Comparison of model results with measured or estimated low-latitude vertical drift velocities (zonal electric fields) shows that the coupled model is capable of reproducing measurements under a variety of conditions. In particular, our model results suggest, from theoretical grounds, a possibility of long-lasting penetration of magnetospheric electric fields to low latitudes during prolonged periods of enhanced convection associated with southward-directed interplanetary magnetic field, although the model probably overestimates the magnitude and duration of such penetration during extremely disturbed conditions. During periods of moderate disturbance, we found surprisingly good overall agreement between model predictions and data, with penetration electric fields accounting for early main phase changes and oscillations in low-latitude vertical drift, while the disturbance dynamo mechanism becomes increasingly important later in the modeled events. Discrepancies between the model results and the observations indicate some of the difficulties in validating these combined numerical models, and the limitations of the available experimental data.

  14. Electric impedance platelet aggregometry in cardiac surgery patients: A comparative study of two technologies.

    PubMed

    Ranucci, Marco; Baryshnikova, Ekaterina; Crapelli, Giulia Beatrice; Ranucci, Matteo; Meloni, Silvia; Pistuddi, Valeria

    2016-01-01

    Platelet function tests are suggested to assess platelet reactivity before cardiac and major non-cardiac surgery. Different point-of-care platelet function tests are available. Among these, electric impedance platelet aggregometry (EIPA) (Multiplate®, MP) is one of the most widely used techniques. Recently, a new EIPA system (Rotem Platelet®, RP) was released. This is a comparative study of platelet function measured with MP and RP. Fifty cardiac surgery patients were admitted to this study. All the patients received a preoperative platelet function test with both the MP and the RP; for each technology, two tests were performed: the ADPtest (investigating P2Y12 receptor platelet reactivity) and the TRAPtest (investigating the thrombin-dependent platelet reactivity). ADP-based platelet reactivity values demonstrated a significant (p = 0.019) correlation between the MP and the RP; and a marginally significant (p = 0.042) correlation for TRAP-based tests. The Bland-Altman analysis of the ADPtest demonstrated a positive bias of 5.94 units (MP > RP) and a percentage error of 88%. For the TRAPtest, there was a positive bias of 12 units (MP > RP) and a percentage error of 89%. In patients who were preoperatively treated with P2Y12 receptor inhibitors, only the MP ADPtest was positively associated with the days from drug discontinuation (p = 0.003). Platelet function assessment with RP greatly differs from the equivalent MP measure, and no correction value can be applied due to the low level of precision. This applies both to ADPtest and TRAPtest. The MP ADPtest is more reliable for platelet reactivity after discontinuation of P2Y12 receptor inhibitors.

  15. Cardiac Mean Electrical Axis in Thoroughbreds—Standardization by the Dubois Lead Positioning System

    PubMed Central

    da Costa, Cássia Fré; Samesima, Nelson; Pastore, Carlos Alberto

    2017-01-01

    Background Different methodologies for electrocardiographic acquisition in horses have been used since the first ECG recordings in equines were reported early in the last century. This study aimed to determine the best ECG electrodes positioning method and the most reliable calculation of mean cardiac axis (MEA) in equines. Materials and Methods We evaluated the electrocardiographic profile of 53 clinically healthy Thoroughbreds, 38 males and 15 females, with ages ranging 2–7 years old, all reared at the São Paulo Jockey Club, in Brazil. Two ECG tracings were recorded from each animal, one using the Dubois lead positioning system, the second using the base-apex method. QRS complex amplitudes were analyzed to obtain MEA values in the frontal plane for each of the two electrode positioning methods mentioned above, using two calculation approaches, the first by Tilley tables and the second by trigonometric calculation. Results were compared between the two methods. Results There was significant difference in cardiac axis values: MEA obtained by the Tilley tables was +135.1° ± 90.9° vs. -81.1° ± 3.6° (p<0.0001), and by trigonometric calculation it was -15.0° ± 11.3° vs. -79.9° ± 7.4° (p<0.0001), base-apex and Dubois, respectively. Furthermore, Dubois method presented small range of variation without statistical or clinical difference by either calculation mode, while there was a wide variation in the base-apex method. Conclusion Dubois improved centralization of the Thoroughbreds' hearts, engendering what seems to be the real frontal plane. By either calculation mode, it was the most reliable methodology to obtain cardiac mean electrical axis in equines. PMID:28095442

  16. Arrhythmias in Patients with Cardiac Implantable Electrical Devices after Implantation of a Left Ventricular Assist Device.

    PubMed

    Rosenbaum, Andrew N; Kremers, Walter K; Duval, Sue; Sakaguchi, Scott; John, Ranjit; Eckman, Peter M

    2016-01-01

    Utilization of continuous-flow left ventricular assist devices (CF-LVADs) for advanced heart failure is increasing, and the role of cardiac implantable electrical devices (CIED) is unclear. Prior studies of the incidence of arrhythmias and shocks are frequently limited by ascertainment. One hundred and seventy-eight patients were examined with a previous CIED who were implanted with a CF-LVAD. Medical history, medications, and CIED data from device interrogations were gathered. A cardiac surgery control group (n = 38) was obtained to control for surgical factors. Several clinically significant events increased after LVAD implantation: treated-zone ventricular arrhythmias (VA; p < 0.01), monitored-zone VA (p < 0.01), antitachycardia pacing (ATP)-terminated episodes (p < 0.01), and shocks (p = 0.01), although administered shocks later decreased (p < 0.01). Presence of a preimplant VA was associated with postoperative VA (odds ratio [OR]: 4.31; confidence interval [CI]: 1.5-12.3, p < 0.01). Relative to cardiac surgery, LVAD patients experienced more perioperative events (i.e., monitored VAs and shocks, p < 0.01 and p = 0.04). Neither implantable cardioverter defibrillator (ICD) shocks before implant nor early or late postimplant arrhythmias or shocks predicted survival (p = 0.07, p = 0.55, and p = 0.55). Our experience demonstrates time-dependent effects on clinically significant arrhythmias after LVAD implantation, including evidence that early LVAD-related arrhythmias may be caused by the unique arrhythmogenic effects of VAD implant.

  17. Effects of muscle electrical stimulation on peak VO2 in cardiac transplant patients.

    PubMed

    Vaquero, A F; Chicharro, J L; Gil, L; Ruiz, M P; Sánchez, V; Lucía, A; Urrea, S; Gómez, M A

    1998-07-01

    Peak oxygen consumption (peak VO2) has become a critical component in the evaluation of heart transplant recipients (HTR). In these patients, peak VO2 remains low after cardiac transplantation mainly because of persisting peripheral limitations in the working muscles. Muscular electrical stimulation, on the other hand, has been shown to enhance the oxidative capacity of healthy muscle. It was the purpose of our investigation to study the effects of ES on the peak VO2 of HTR. Fourteen (11 males and 3 females) HTR (age: 57+/-7yr, mean +/- SD; height: 163+/-7 cm, weight: 70.5+/-8.6 kg) were selected as subjects and each of them was randomly assigned to one of two groups: (a) group EXP (n = 7), receiving electrical stimulation on both quadriceps muscles during a period of 8 weeks, and (b) group CONT (n = 7), not receiving electrical stimulation. Before (PRE) and after (POST) the aforementioned 8-week period, respectively, all the subjects performed a cardiopulmonary exercise test (ramp protocol) on a cycle ergometer for peak VO2 determination. PRE values of peak VO2 were similar in both groups (17.1+/-2.0 vs 16.9+/-3.8ml x kg(-1) x min(-1) in EXP and CONT, respectively). However, peak values of VO2 significantly increased in EXP (p < 0.05) after the period of electrical stimulation (POST peak VO2: 18.7+/-2.0ml x kg(-1)), whereas no change was observed in CONT (POST peak VO2: 16.2+/-3.2 ml x kg(-1) x min(-1)). In conclusion, electrical stimulation could therefore be used to improve the functional capacity of HTR, and might be included in the rehabilitation programs of this population group.

  18. Simulation method for cardiac stroke volume estimation by intracardiac electrical impedance measurement.

    PubMed

    Barak, C; Leviatan, Y; Inbar, G F; Hoekstein, K N

    1992-09-01

    Using the electrical impedance measurement technique to investigate stroke volume estimation, three models of the ventricle were simulated. A four-electrode impedance catheter was used; two electrodes to set up an electric field in the model and the other two to measure the potential difference. A new approach, itself an application of the quasi-static case of a method used to solve electromagnetic field problems, was used to solve the electric field in the model. The behaviour of the estimation is examined with respect to the electrode configuration on the catheter and to catheter location with respect to the ventricle walls. Cardiac stroke volume estimation was found to be robust to catheter location generating a 10 per cent error for an offset of 40 per cent of the catheter from the chamber axis and rotation of 20 degrees with respect to the axis. The electrode configuration has a dominant effect on the sensitivity and accuracy of the estimation. Certain configurations gave high accuracy, whereas in others high sensitivity was found with lower accuracy. This led to the conclusion that the electrode configuration should be carefully chosen according to the desired criteria.

  19. Bioreactor for modulation of cardiac microtissue phenotype by combined static stretch and electrical stimulation

    PubMed Central

    Miklas, Jason W; Nunes, Sara S; Sofla, Aarash; Reis, Lewis A; Pahnke, Aric; Xiao, Yun; Laschinger, Carol; Radisic, Milica

    2014-01-01

    We describe here a bioreactor capable of simultaneously applying mechanical and electrical field stimulation in conjunction with static strain and on-line force of contraction measurements. It consisted of a polydimethylsiloxane (PDMS) tissue chamber and a pneumatically driven stretch platform. The chamber contained eight tissue microwells (8.05 mm in length and 2.5 mm in width) with a pair of posts (2.78 mm in height and 0.8 mm in diameter) in each well to serve as fixation points and for measurements of contraction force. Carbon rods, stimulating electrodes, were placed into the PDMS chamber such that one pair stimulated four microwells. For feasibility studies, neonatal rat cardiomyocytes were seeded in collagen gels into the microwells. Following three days of gel compaction, electrical field stimulation at 3–4 V/cm and 1Hz, mechanical stimulation of 5% static strain or electromechanical stimulation (field stimulation at 3–4 V/cm, 1Hz and 5% static strain) were applied for 3 days. Cardiac microtissues subjected to electromechanical stimulation exhibited elevated amplitude of contraction and improved sarcomere structure as evidenced by sarcomeric α-actinin, actin and troponin T staining compared to microtissues subjected to electrical or mechanical stimulation alone or non-stimulated controls. The expression of atrial natriuretic factor and brain natriuretic peptide was also elevated in the electromechanically stimulated group. PMID:24876342

  20. Role of the basement membrane in regulation of cardiac electrical properties.

    PubMed

    Yang, Huaxiao; Borg, Thomas K; Wang, Zhonghai; Ma, Zhen; Gao, Bruce Z

    2014-06-01

    In the heart muscle, each adult cardiomyocyte is enclosed by a basement membrane (BM). This innermost extracellular matrix is a layered assembly of laminin, collagen IV, glycoproteins, and proteoglycans. In this study, the role of the BM network in regulation of the electrical properties of neonatal cardiomyocytes (NCMs) cultured on an aligned collagen I gel was investigated using a multielectrode array (MEA). A laminin antibody was added to the culture medium for 48-120 h to conjugate newly secreted laminin. Then, morphology of the NCMs on an MEA was monitored using a phase contrast microscope, and the BM network that was immunocytostained for laminin was imaged using a fluorescence microscope. When the BM laminin was absent in this culture model, dramatic changes in NCM morphology were observed. Simultaneously, the MEA-recorded cardiac field potential showed changes compared to that from the control groups: The period of contraction shortened to 1/2 of that from the control groups, and the waveform of the calcium influx shifted from a flat plateau to a peak-like waveform, indicating that the electrical properties of the NCMs were closely related to the components and distribution of the BM network.

  1. Cell number per spheroid and electrical conductivity of nanowires influence the function of silicon nanowired human cardiac spheroids.

    PubMed

    Tan, Yu; Richards, Dylan; Coyle, Robert C; Yao, Jenny; Xu, Ruoyu; Gou, Wenyu; Wang, Hongjun; Menick, Donald R; Tian, Bozhi; Mei, Ying

    2017-03-15

    Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) provide an unlimited cell source to treat cardiovascular diseases, the leading cause of death worldwide. However, current hiPSC-CMs retain an immature phenotype that leads to difficulties for integration with adult myocardium after transplantation. To address this, we recently utilized electrically conductive silicon nanowires (e-SiNWs) to facilitate self-assembly of hiPSC-CMs to form nanowired hiPSC cardiac spheroids. Our previous results showed addition of e-SiNWs effectively enhanced the functions of the cardiac spheroids and improved the cellular maturation of hiPSC-CMs. Here, we examined two important factors that can affect functions of the nanowired hiPSC cardiac spheroids: (1) cell number per spheroid (i.e., size of the spheroids), and (2) the electrical conductivity of the e-SiNWs. To examine the first factor, we prepared hiPSC cardiac spheroids with four different sizes by varying cell number per spheroid (∼0.5k, ∼1k, ∼3k, ∼7k cells/spheroid). Spheroids with ∼3k cells/spheroid was found to maximize the beneficial effects of the 3D spheroid microenvironment. This result was explained with a semi-quantitative theory that considers two competing factors: 1) the improved 3D cell-cell adhesion, and 2) the reduced oxygen supply to the center of spheroids with the increase of cell number. Also, the critical role of electrical conductivity of silicon nanowires has been confirmed in improving tissue function of hiPSC cardiac spheroids. These results lay down a solid foundation to develop suitable nanowired hiPSC cardiac spheroids as an innovative cell delivery system to treat cardiovascular diseases.

  2. Overexpression of connexin 43 using a retroviral vector improves electrical coupling of skeletal myoblasts with cardiac myocytes in vitro

    PubMed Central

    Tolmachov, Oleg; Ma, Yu-Ling; Themis, Michael; Patel, Pravina; Spohr, Hilmar; MacLeod, Kenneth T; Ullrich, Nina D; Kienast, Yvonne; Coutelle, Charles; Peters, Nicholas S

    2006-01-01

    Background Organ transplantation is presently often the only available option to repair a damaged heart. As heart donors are scarce, engineering of cardiac grafts from autologous skeletal myoblasts is a promising novel therapeutic strategy. The functionality of skeletal muscle cells in the heart milieu is, however, limited because of their inability to integrate electrically and mechanically into the myocardium. Therefore, in pursuit of improved cardiac integration of skeletal muscle grafts we sought to modify primary skeletal myoblasts by overexpression of the main gap-junctional protein connexin 43 and to study electrical coupling of connexin 43 overexpressing myoblasts to cardiac myocytes in vitro. Methods To create an efficient means for overexpression of connexin 43 in skeletal myoblasts we constructed a bicistronic retroviral vector MLV-CX43-EGFP expressing the human connexin 43 cDNA and the marker EGFP gene. This vector was employed to transduce primary rat skeletal myoblasts in optimised conditions involving a concomitant use of the retrovirus immobilising protein RetroNectin® and the polycation transduction enhancer Transfectam®. The EGFP-positive transduced cells were then enriched by flow cytometry. Results More than four-fold overexpression of connexin 43 in the transduced skeletal myoblasts, compared with non-transduced cells, was shown by Western blotting. Functionality of the overexpressed connexin 43 was demonstrated by microinjection of a fluorescent dye showing enhanced gap-junctional intercellular transfer in connexin 43 transduced myoblasts compared with transfer in non-transduced myoblasts. Rat cardiac myocytes were cultured in multielectrode array culture dishes together with connexin 43/EGFP transduced skeletal myoblasts, control non-transduced skeletal myoblasts or alone. Extracellular field action potential activation rates in the co-cultures of connexin 43 transduced skeletal myoblasts with cardiac myocytes were significantly higher than

  3. Magnetic storms and induction hazards

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Balch, Christopher

    2014-01-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

  4. Modeling the response of normal and ischemic cardiac tissue to electrical stimulation

    NASA Astrophysics Data System (ADS)

    Kandel, Sunil Mani

    Heart disease, the leading cause of death worldwide, is often caused by ventricular fibrillation. A common treatment for this lethal arrhythmia is defibrillation: a strong electrical shock that resets the heart to its normal rhythm. To design better defibrillators, we need a better understanding of both fibrillation and defibrillation. Fundamental mysteries remain regarding the mechanism of how the heart responds to a shock, particularly anodal shocks and the resultant hyperpolarization. Virtual anodes play critical roles in defibrillation, and one cannot build better defibrillators until these mechanisms are understood. We are using mathematical modeling to numerically simulate observed phenomena, and are exploring fundamental mechanisms responsible for the heart's electrical behavior. Such simulations clarify mechanisms and identify key parameters. We investigate how systolic tissue responds to an anodal shock and how refractory tissue reacts to hyperpolarization by studying the dip in the anodal strength-interval curve. This dip is due to electrotonic interaction between regions of depolarization and hyperpolarization following a shock. The dominance of the electrotonic mechanism over calcium interactions implies the importance of the spatial distribution of virtual electrodes. We also investigate the response of localized ischemic tissue to an anodal shock by modeling a regional elevation of extracellular potassium concentration. This heterogeneity leads to action potential instability, 2:1 conduction block (alternans), and reflection-like reentry at the boarder of the normal and ischemic regions. This kind of reflection (reentry) occurs due to the delay between proximal and distal segments to re-excite the proximal segment. Our numerical simulations are based on the bidomain model, the state-of-the-art mathematical description of how cardiac tissue responds to shocks. The dynamic LuoRudy model describes the active properties of the membrane. To model ischemia

  5. Cardiac arrest with pulseless electrical activity associated with methylphenidate in an adolescent with a normal baseline echocardiogram.

    PubMed

    Daly, Michael W; Custer, Geoffrey; McLeay, Peter D

    2008-11-01

    Recent concerns of adverse cardiac events associated with drugs used to treat attention-deficit-hyperactivity disorder (ADHD) have prompted debate over whether these drugs are truly safe. We describe a 17-year-old boy with a normal baseline echocardiogram who had been taking methylphenidate for ADHD for 18 months and experienced cardiac arrest. Emergency personnel attempted to resuscitate him, performing defibrillation twice for ventricular fibrillation, with subsequent pulseless electrical activity. The patient was immediately taken to the hospital where he received continued resuscitation, intravenous boluses of cardiac drugs, and additional defibrillation. A persistent pulsatile rhythm returned about 2 minutes after arrival. Overall, the patient was pulseless for 22 minutes. Emergency cardiac catheterization revealed wall motion abnormalities without coronary lesions. He was mechanically ventilated and was transferred to the intensive care unit, where he remained comatose. Neurologic studies performed the next day revealed diffuse encephalopathy due to anoxic brain injury. An echocardiogram on day 3 showed slightly improved left ventricular systolic function, which improved further by day 15. As the patient did not regain purposeful movement, he was discharged to a rehabilitation facility on day 33. The patient's methylphenidate therapy had been started at an appropriate dose of 18 mg/day and titrated over a period of 3 months up to 36 mg/day, which he continued until the event. The drug had been discontinued on admission, was not restarted, and for the next 2 years, the patient experienced no further cardiac events, although his severe mental deficiencies persisted. Use of the Naranjo adverse drug reaction probability scale indicated a probable relationship (score of 6) between the patient's adverse cardiac event and methylphenidate. To our knowledge, this is the first case report of a patient with documentation of a normal baseline echocardiogram who

  6. Abnormal sodium current properties contribute to cardiac electrical and contractile dysfunction in a mouse model of myotonic dystrophy type 1.

    PubMed

    Algalarrondo, Vincent; Wahbi, Karim; Sebag, Frédéric; Gourdon, Geneviève; Beldjord, Chérif; Azibi, Kamel; Balse, Elise; Coulombe, Alain; Fischmeister, Rodolphe; Eymard, Bruno; Duboc, Denis; Hatem, Stéphane N

    2015-04-01

    Myotonic dystrophy type 1 (DM1) is the most common neuromuscular disorder and is associated with cardiac conduction defects. However, the mechanisms of cardiac arrhythmias in DM1 are unknown. We tested the hypothesis that abnormalities in the cardiac sodium current (INa) are involved, and used a transgenic mouse model reproducing the expression of triplet expansion observed in DM1 (DMSXL mouse). The injection of the class-I antiarrhythmic agent flecainide induced prominent conduction abnormalities and significantly lowered the radial tissular velocities and strain rate in DMSXL mice compared to WT. These abnormalities were more pronounced in 8-month-old mice than in 3-month-old mice. Ventricular action potentials recorded by standard glass microelectrode technique exhibited a lower maximum upstroke velocity [dV/dt](max) in DMSXL. This decreased [dV/dt](max) was associated with a 1.7 fold faster inactivation of INa in DMSXL myocytes measured by the whole-cell patch-clamp technique. Finally in the DMSXL mouse, no mutation in the Scn5a gene was detected and neither cardiac fibrosis nor abnormalities of expression of the sodium channel protein were observed. Therefore, alterations in the sodium current markedly contributed to electrical conduction block in DM1. This result should guide pharmaceutical and clinical research toward better therapy for the cardiac arrhythmias associated with DM1.

  7. The Electrical Activity of Canine Cardiac Purkinje Fibers in Sodium-Free, Calcium-Rich Solutions

    PubMed Central

    Aronson, Ronald S.; Cranefield, Paul F.

    1973-01-01

    Propagated action potentials can be obtained in canine cardiac Purkinje fibers exposed to Na-free solutions containing no inorganic cation other than Ca and K. Essentially similar action potentials are obtained if Na is replaced by tetraethylammonium (TEA), tetramethylammonium (TMA), or choline. In a solution containing 128 mM TEA and 16.2 mM Ca the characteristics of these electrical responses were: maximum diastolic potential, -59 ± 3.3 mV; overshoot, 20 ± 6.8 mV; maximum upstroke velocity, 3.7 ± 2.3 V/s; conduction velocity, 0.1 m/s; and action potential duration, 360 ± 45 ms. The magnitude of the overshoot varied with log Cao with a slope of about 30 mV/10-fold concentration change. The upstroke velocity was an approximately linear function of Cao. The active response was greatly diminished or abolished by Mn and D-600 but was unaffected by tetrodotoxin. These Ca-dependent responses appeared in a region of transmembrane potential (about -50 mV) at which the rapid Na-dependent upstroke is abolished even when Na is present. PMID:4708407

  8. Regulation of Ca2+ and electrical alternans in cardiac myocytes: role of CAMKII and repolarizing currents.

    PubMed

    Livshitz, Leonid M; Rudy, Yoram

    2007-06-01

    Alternans of cardiac repolarization is associated with arrhythmias and sudden death. At the cellular level, alternans involves beat-to-beat oscillation of the action potential (AP) and possibly Ca(2+) transient (CaT). Because of experimental difficulty in independently controlling the Ca(2+) and electrical subsystems, mathematical modeling provides additional insights into mechanisms and causality. Pacing protocols were conducted in a canine ventricular myocyte model with the following results: 1) CaT alternans results from refractoriness of the sarcoplasmic reticulum Ca(2+) release system; alternation of the L-type calcium current has a negligible effect; 2) CaT-AP coupling during late AP occurs through the sodium-calcium exchanger and underlies AP duration (APD) alternans; 3) increased Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activity extends the range of CaT and APD alternans to slower frequencies and increases alternans magnitude; its decrease suppresses CaT and APD alternans, exerting an antiarrhythmic effect; and 4) increase of the rapid delayed rectifier current (I(Kr)) also suppresses APD alternans but without suppressing CaT alternans. Thus CaMKII inhibition eliminates APD alternans by eliminating its cause (CaT alternans) while I(Kr) enhancement does so by weakening CaT-APD coupling. The simulations identify combined CaMKII inhibition and I(Kr) enhancement as a possible antiarrhythmic intervention.

  9. Development of Electrically Conductive Double-Network Hydrogels via One-Step Facile Strategy for Cardiac Tissue Engineering.

    PubMed

    Yang, Boguang; Yao, Fanglian; Hao, Tong; Fang, Wancai; Ye, Lei; Zhang, Yabin; Wang, Yan; Li, Junjie; Wang, Changyong

    2016-02-18

    Cardiac tissue engineering is an effective method to treat the myocardial infarction. However, the lack of electrical conductivity of biomaterials limits their applications. In this work, a homogeneous electronically conductive double network (HEDN) hydrogel via one-step facile strategy is developed, consisting of a rigid/hydrophobic/conductive network of chemical crosslinked poly(thiophene-3-acetic acid) (PTAA) and a flexible/hydrophilic/biocompatible network of photo-crosslinking methacrylated aminated gelatin (MAAG). Results suggest that the swelling, mechanical, and conductive properties of HEDN hydrogel can be modulated via adjusting the ratio of PTAA network to MAAG network. HEDN hydrogel has Young's moduli ranging from 22.7 to 493.1 kPa, and its conductivity (≈10(-4) S cm(-1)) falls in the range of reported conductivities for native myocardium tissue. To assess their biological activity, the brown adipose-derived stem cells (BADSCs) are seeded on the surface of HEDN hydrogel with or without electrical stimulation. Our data show that the HEDN hydrogel can support the survival and proliferation of BADSCs, and that it can improve the cardiac differentiation efficiency of BADSCs and upregulate the expression of connexin 43. Moreover, electrical stimulation can further improve this effect. Overall, it is concluded that the HEDN hydrogel may represent an ideal scaffold for cardiac tissue engineering.

  10. Mild electrical pulse current stimulation upregulates S100A4 and promotes cardiogenesis in MSC and cardiac myocytes coculture monolayer.

    PubMed

    Wen, Lei; Zhang, Changhai; Nong, Yaoming; Yao, Qing; Song, Zhiyuan

    2013-01-01

    Parietal endoderm-secreted S100A4 promotes early cardiomyogenesis in embryoid bodies [1]. After an acute ischemic event, S100A4 protein appears in cardiac myocytes only in the border zone in rat and human hearts [2]. In wound research, a large outward current of 4 μA/cm(2) was always measured at the wound edges of rat cornea and human skin [3]. We hypothesize that a special electrical circumstance at the border zone may contribute to the phenomenon. An electric stimulation system was designed to give the cells electric pulse current stimulation (EPCS), the feature of the signal is pulse polarity altered one after another, rectangular 2 ms, 2 Hz, 40 μA. This intensity of stimulation is proved to be safe to cardiac myocytes (both in structure and beating behavior compared with the cardiac myocytes which do not receive stimulation) and MSCs (in cell vitality, proliferation, cell cycle, and gap junction generation potential) through our previous work. Canine MSCs are capable of generating voltage-sensitive Ca(2+) channel and Na(+) channels and generating the Ca(2+) handling system during differentiation. We found that CD44 was reduced in the MSCs monolayer treated with EPCS, compared with non-stimulated MSCs; and EPCS MSCs (3 h/day, 6 h/day, 5 days) showed an 14.04 ± 3.44 and 14.55 ± 3.97 % reduction in CD44, compared with the cotemporary MSCs; these reveal that CD44 reduction amplitude is not correlated with time for EPCS disposure and CD29 (integrin β1) expression is not affected by EPCS exposure. EPCS was given to the MSCs and cardiac myocytes coculture monolayer (ratio 3:1) for different time (1, 3, and 6 h/day) for 4 days to see the biological effects. Gap junction protein and troponin T show an increase after EPCS. We found that the gap junction protein Cx43 increased with treating time-in the EPCS group, it exhibited 1.5 and 1.7 fold in the 3 h/day group and 6 h/day group (P < 0.01), and troponin T exhibited to about 3.6 and 4.4 fold in the 3 h/day group (P

  11. Removal of pinned scroll waves in cardiac tissues by electric fields in a generic model of three-dimensional excitable media

    PubMed Central

    Pan, De-Bei; Gao, Xiang; Feng, Xia; Pan, Jun-Ting; Zhang, Hong

    2016-01-01

    Spirals or scroll waves pinned to heterogeneities in cardiac tissues may cause lethal arrhythmias. To unpin these life-threatening spiral waves, methods of wave emission from heterogeneities (WEH) induced by low-voltage pulsed DC electric fields (PDCEFs) and circularly polarized electric fields (CPEFs) have been used in two-dimensional (2D) cardiac tissues. Nevertheless, the unpinning of scroll waves in three-dimensional (3D) cardiac systems is much more difficult than that of spiral waves in 2D cardiac systems, and there are few reports on the removal of pinned scroll waves in 3D cardiac tissues by electric fields. In this article, we investigate in detail the removal of pinned scroll waves in a generic model of 3D excitable media using PDCEF, AC electric field (ACEF) and CPEF, respectively. We find that spherical waves can be induced from the heterogeneities by these electric fields in initially quiescent excitable media. However, only CPEF can induce spherical waves with frequencies higher than that of the pinned scroll wave. Such higher-frequency spherical waves induced by CPEF can be used to drive the pinned scroll wave out of the cardiac systems. We hope this remarkable ability of CPEF can provide a better alternative to terminate arrhythmias caused by pinned scroll waves. PMID:26905367

  12. Removal of pinned scroll waves in cardiac tissues by electric fields in a generic model of three-dimensional excitable media.

    PubMed

    Pan, De-Bei; Gao, Xiang; Feng, Xia; Pan, Jun-Ting; Zhang, Hong

    2016-02-24

    Spirals or scroll waves pinned to heterogeneities in cardiac tissues may cause lethal arrhythmias. To unpin these life-threatening spiral waves, methods of wave emission from heterogeneities (WEH) induced by low-voltage pulsed DC electric fields (PDCEFs) and circularly polarized electric fields (CPEFs) have been used in two-dimensional (2D) cardiac tissues. Nevertheless, the unpinning of scroll waves in three-dimensional (3D) cardiac systems is much more difficult than that of spiral waves in 2D cardiac systems, and there are few reports on the removal of pinned scroll waves in 3D cardiac tissues by electric fields. In this article, we investigate in detail the removal of pinned scroll waves in a generic model of 3D excitable media using PDCEF, AC electric field (ACEF) and CPEF, respectively. We find that spherical waves can be induced from the heterogeneities by these electric fields in initially quiescent excitable media. However, only CPEF can induce spherical waves with frequencies higher than that of the pinned scroll wave. Such higher-frequency spherical waves induced by CPEF can be used to drive the pinned scroll wave out of the cardiac systems. We hope this remarkable ability of CPEF can provide a better alternative to terminate arrhythmias caused by pinned scroll waves.

  13. Removal of pinned scroll waves in cardiac tissues by electric fields in a generic model of three-dimensional excitable media

    NASA Astrophysics Data System (ADS)

    Pan, De-Bei; Gao, Xiang; Feng, Xia; Pan, Jun-Ting; Zhang, Hong

    2016-02-01

    Spirals or scroll waves pinned to heterogeneities in cardiac tissues may cause lethal arrhythmias. To unpin these life-threatening spiral waves, methods of wave emission from heterogeneities (WEH) induced by low-voltage pulsed DC electric fields (PDCEFs) and circularly polarized electric fields (CPEFs) have been used in two-dimensional (2D) cardiac tissues. Nevertheless, the unpinning of scroll waves in three-dimensional (3D) cardiac systems is much more difficult than that of spiral waves in 2D cardiac systems, and there are few reports on the removal of pinned scroll waves in 3D cardiac tissues by electric fields. In this article, we investigate in detail the removal of pinned scroll waves in a generic model of 3D excitable media using PDCEF, AC electric field (ACEF) and CPEF, respectively. We find that spherical waves can be induced from the heterogeneities by these electric fields in initially quiescent excitable media. However, only CPEF can induce spherical waves with frequencies higher than that of the pinned scroll wave. Such higher-frequency spherical waves induced by CPEF can be used to drive the pinned scroll wave out of the cardiac systems. We hope this remarkable ability of CPEF can provide a better alternative to terminate arrhythmias caused by pinned scroll waves.

  14. Groundwater discharge to wetlands driven by storm and flood events: Quantification using continuous Radon-222 and electrical conductivity measurements and dynamic mass-balance modelling

    NASA Astrophysics Data System (ADS)

    Gilfedder, B. S.; Frei, S.; Hofmann, H.; Cartwright, I.

    2015-09-01

    The dynamic response of groundwater discharge to external influences such as rainfall is an often neglected part of water and solute balances in wetlands. Here we develop a new field platform for long-term continuous 222Rn and electrical conductivity (EC) measurements at Sale Wetland, Australia to study the response of groundwater discharge to storm and flood events. The field measurements, combined with dynamic mass-balance modelling, demonstrate that the groundwater flux can increase from 3 to ∼20 mm d-1 following storms and up to 5 mm d-1 on the receding limb of floods. The groundwater pulses are likely produced by activation of local groundwater flow paths by water ponding on the surrounding flood plains. While 222Rn is a sensitive tracer for quantifying transient groundwater discharge, the mass-balance used to estimate fluxes is sensitive to parameterisation of gas exchange (k) with the atmosphere. Comparison of six equations for calculating k showed that, based on parameterisation of k alone, the groundwater flux estimate could vary by 58%. This work shows that neglecting transient processes will lead to errors in water and solute flux estimates based on infrequent point measurements. This could be particularly important for surface waters connected to contaminated or saline groundwater systems.

  15. A working hypothesis for connections between electrically-induced changes in cloud microphysics and storm vorticity, with possible effects on circulation

    NASA Astrophysics Data System (ADS)

    Tinsley, Brian A.

    2012-09-01

    This paper outlines, and explores the uncertainties in, hypothesized connections between a series of processes that could explain two long-standing puzzles; those of (1) the observed winter storm vorticity responses to atmospheric energy inputs that change the ionosphere-earth current density, Jz, that appear to involve storm invigoration, and (2) changes in anti-cyclonic blocking and circulation that include the observed colder winters in Great Britain and western Europe at solar minima, and especially at extended solar minima. A working hypothesis for the mechanism responsible for (1) is that the flow of Jz through conductivity gradients, as in stratified cloud layers and fog, especially with sea-salt aerosol haze over the high latitude winter oceans, deposits electric changes on droplets and aerosol particles; most importantly on cloud condensation nuclei (CCN). These electric charges modulate scavenging of the particles in clouds and haze layers, increasing the concentration of small CCN and decreasing the concentration of large CCN. When further cloud formation occurs there is increased concentration of small droplets and decreased concentration of large ones, reducing coalescence and the production of rain. Thus updrafts carry more liquid water above the freezing level, and there the increased production of ice releases more latent heat and invigorates the updraft (the Rosenfeld mechanism), leading to increased vorticity. Here we explore the major uncertainties for the reality of the above chain of physical processes. A consequence of cumulative cyclonic vorticity increases is increases in downstream anti-cyclonic blocking. A further working hypothesis for (2) is that the invigoration may be large enough to contribute to the observed increases in blocking in winters at solar minima (high Jz) in the North Atlantic, that result in colder winters in the UK and northern Europe.

  16. [Electrical cardioversion in the treatment of cardiac arrhythmias during pregnancy--case report and review of literature].

    PubMed

    Gałczyński, Krzysztof; Marciniak, Beata; Kudlicki, Janusz; Kimber-Trojnar, Zaneta; Leszczyńska-Gorzelak, Bozena; Oleszczukz, Jan

    2013-10-01

    The incidence of cardiac arrhythmias is estimated et 1.2 per 1000 pregnancies, usually in the third trimester and 50% of them are asymptomatic. They may appear for the first time in pregnancy or have a recurring character An important risk factor related to their appearance is the presence of structural heart disease, which complicates < 1% of pregnancies. Generally the symptoms are mild and the treatment is not necessary but in some cases pharmacotherapy is necessary Pharmacotherapy must be a compromise between the potentially adverse effects of drugs on the fetus and the beneficial effects on the cardiovascular system of the mother. Due to the development of cardiac surgery many women with heart defects reach reproductive age and become pregnant. Therefore this problem will be faced more and more often in clinical practice. In addition to pharmacological methods some cardiac arrhythmias may require urgent, life-saving procedures. External electrical cardioversion is associated with the application of certain amount of energy via two electrodes placed on the thorax. It is used to treat hemodynamically unstable supraventricular tachycardias, including atrial fibrillation and atrial flutter Also in hemodynamically stable patients in whom drug therapy was ineffective elective electrical cardioversion can be use to convert cardiac arrhythmia to sinus rhythm. We present a case of a 33 years old patient with congenital heart disease surgically corrected in childhood who had first incident of atrial flutter in pregnancy. Arrhytmia occured in 26th week of gestation. The patient was hemodynamically stable and did not approve electrical cardioversion as a method of treatment therefore pharmacotherapy was started. Heart rate was controled with metoprolol and digoxin, warfarin was used to anticoagulation. Calcium and potassium were also given. Described therapy did not convert atrial flutter to sinus rhythm therefore in 33rd week of gestation after patient's approval

  17. Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

  18. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Cid, Consuelo; Palacios, Judith; Saiz, Elena; Guerrero, Antonio; Cerrato, Yolanda

    2014-10-01

    Extreme geomagnetic storms are considered as one of the major natural hazards for technology-dependent society. Geomagnetic field disturbances can disrupt the operation of critical infrastructures relying on space-based assets, and can also result in terrestrial effects, such as the Quebec electrical disruption in 1989. Forecasting potential hazards is a matter of high priority, but considering large flares as the only criterion for early-warning systems has demonstrated to release a large amount of false alarms and misses. Moreover, the quantification of the severity of the geomagnetic disturbance at the terrestrial surface using indices as Dst cannot be considered as the best approach to give account of the damage in utilities. High temporal resolution local indices come out as a possible solution to this issue, as disturbances recorded at the terrestrial surface differ largely both in latitude and longitude. The recovery phase of extreme storms presents also some peculiar features which make it different from other less intense storms. This paper goes through all these issues related to extreme storms by analysing a few events, highlighting the March 1989 storm, related to the Quebec blackout, and the October 2003 event, when several transformers burnt out in South Africa.

  19. The Cause of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Nagatsuma, T.

    2001-12-01

    Although the cause of magnetic storms is important issue, the exact mechanism of the storm development is still controversial. Two mechanisms of storm development are considered. One is that the frequent substorm activity injects high-energy particles to the inner magnetosphere; the other is that the enhanced convection plays a role. Further, Iyermori and Rao [1996] shows that the substorm reduces the development of storms. On the contrary, magnetospheric convections and magnetic storms correspond different solar wind parameter. It is well known that the variations of the magnetospheric convection correspond to merging electric field (Em) by Kan and Lee [1979]. However, the variations of the magenetic storm correspond Ey [e.g. Burton et al., 1975]. This suggests that magnetospheric convection and magnetic storm are independent phenomena. However, we cannot discuss the independency of two phenomena since the difference between Em and Ey is small, under usual solar wind condition. We have analyzed Nov. 8, 1998 storm event, since the big difference between Em and Ey exists during 6 hours. The enhancement of Ey terminates first, and Em continues to enhance more than 6 hours after that. Although the variation of the storm estimated from SYM-H(Dst) index corresponds to Ey, that of the magnetospheric convection estimated from PC index corresponds to Em. This shows that the development of the storm terminate although the magnetospheric convection still enhances. This result suggests that the development of magnetic storms is independent from enhanced convection and the magnetic storm is directly caused by the enhancement of Ey in the solar wind.

  20. An evaluation of two conducted electrical weapons and two probe designs using a swine comparative cardiac safety model.

    PubMed

    Dawes, Donald Murray; Ho, Jeffrey D; Moore, Johanna C; Miner, James R

    2013-09-01

    Despite human laboratory and field studies that have demonstrated a reasonable safety profile for TASER brand conducted electrical weapons (CEW), the results of some swine studies and arrest related deaths temporal to the use of the CEWs continue to raise questions regarding cardiac safety. TASER International, Inc., has released a new CEW, the TASER X2, touted to have a better safety profile than its long-standing predecessor, the TASER X26. We have developed a model to assess the relative cardiac safety of CEWs and used it to compare the TASER X2 and the TASER X26. This safety model was also used to assess the relative safety of an experimental probe design as compared to the standard steel probe. Our results suggest that the TASER X2 has an improved safety margin over the TASER X26. The new probe design also has promise for enhanced cardiac safety, although may have some disadvantages when compared to the existing design which would make field use impractical.

  1. Electrical Wave Propagation in an Anisotropic Model of the Left Ventricle Based on Analytical Description of Cardiac Architecture

    PubMed Central

    Pravdin, Sergey F.; Dierckx, Hans; Katsnelson, Leonid B.; Solovyova, Olga; Markhasin, Vladimir S.; Panfilov, Alexander V.

    2014-01-01

    We develop a numerical approach based on our recent analytical model of fiber structure in the left ventricle of the human heart. A special curvilinear coordinate system is proposed to analytically include realistic ventricular shape and myofiber directions. With this anatomical model, electrophysiological simulations can be performed on a rectangular coordinate grid. We apply our method to study the effect of fiber rotation and electrical anisotropy of cardiac tissue (i.e., the ratio of the conductivity coefficients along and across the myocardial fibers) on wave propagation using the ten Tusscher–Panfilov (2006) ionic model for human ventricular cells. We show that fiber rotation increases the speed of cardiac activation and attenuates the effects of anisotropy. Our results show that the fiber rotation in the heart is an important factor underlying cardiac excitation. We also study scroll wave dynamics in our model and show the drift of a scroll wave filament whose velocity depends non-monotonically on the fiber rotation angle; the period of scroll wave rotation decreases with an increase of the fiber rotation angle; an increase in anisotropy may cause the breakup of a scroll wave, similar to the mother rotor mechanism of ventricular fibrillation. PMID:24817308

  2. Efficient simulation of cardiac electrical propagation using high order finite elements.

    PubMed

    Arthurs, Christopher J; Bishop, Martin J; Kay, David

    2012-05-20

    We present an application of high order hierarchical finite elements for the efficient approximation of solutions to the cardiac monodomain problem. We detail the hurdles which must be overcome in order to achieve theoretically-optimal errors in the approximations generated, including the choice of method for approximating the solution to the cardiac cell model component. We place our work on a solid theoretical foundation and show that it can greatly improve the accuracy in the approximation which can be achieved in a given amount of processor time. Our results demonstrate superior accuracy over linear finite elements at a cheaper computational cost and thus indicate the potential indispensability of our approach for large-scale cardiac simulation.

  3. Efficient simulation of cardiac electrical propagation using high order finite elements

    PubMed Central

    Arthurs, Christopher J.; Bishop, Martin J.; Kay, David

    2012-01-01

    We present an application of high order hierarchical finite elements for the efficient approximation of solutions to the cardiac monodomain problem. We detail the hurdles which must be overcome in order to achieve theoretically-optimal errors in the approximations generated, including the choice of method for approximating the solution to the cardiac cell model component. We place our work on a solid theoretical foundation and show that it can greatly improve the accuracy in the approximation which can be achieved in a given amount of processor time. Our results demonstrate superior accuracy over linear finite elements at a cheaper computational cost and thus indicate the potential indispensability of our approach for large-scale cardiac simulation. PMID:24976644

  4. Frontal brain electrical asymmetry and cardiac vagal tone predict biased attention to social threat.

    PubMed

    Miskovic, Vladimir; Schmidt, Louis A

    2010-03-01

    Individual differences in attention biases for motivationally significant stimuli have been reported in clinical and normative populations. Few studies, however, have attempted to examine potential biological mechanisms underlying differences in the cognitive processing of emotional stimuli. The present study examined the extent to which two well-validated psychophysiological vulnerability markers of affective style [i.e., frontal electroencephalogram (EEG) asymmetry and cardiac vagal tone] predicted biased attention toward rapid presentations (approximately 250 ms) of angry and happy facial expressions. We found that right frontal EEG asymmetry and low cardiac vagal tone, taken together, predicted approximately 37% of the variability in attentional vigilance for angry faces. Frontal EEG asymmetry and cardiac vagal tone did not predict attention for happy faces, independently of each other. Our results provide preliminary evidence that two well established psychophysiological indicators of affective style bias early processing of motivationally salient stimuli.

  5. [Parameters of cardiac muscle repolarization on the electrocardiogram when changing anatomical and electric position of the heart].

    PubMed

    Chaĭkovskiĭ, I A; Baum, O V; Popov, L A; Voloshin, V I; Budnik, N N; Frolov, Iu A; Kovalenko, A S

    2014-01-01

    While discussing the diagnostic value of the single channel electrocardiogram a set of theoretical considerations emerges inevitably, one of the most important among them is the question about dependence of the electrocardiogram parameters from the direction of electrical axis of heart. In other words, changes in what of electrocardiogram parameters are in fact liable to reflect pathological processes in myocardium, and what ones are determined by extracardiac factors, primarily by anatomic characteristics of patients. It is arguable that while analyzing electrocardiogram it is necessary to orient to such physiologically based informative indexes as ST segment displacement. Also, symmetry of the T wave shape is an important parameter which is independent of patients anatomic features. The results obtained are of interest for theoretical and applied aspects of the biophysics of the cardiac electric field.

  6. Enhanced Cardiac Differentiation of Human Cardiovascular Disease Patient-Specific Induced Pluripotent Stem Cells by Applying Unidirectional Electrical Pulses Using Aligned Electroactive Nanofibrous Scaffolds.

    PubMed

    Mohammadi Amirabad, Leila; Massumi, Mohammad; Shamsara, Mehdi; Shabani, Iman; Amari, Afshin; Mossahebi Mohammadi, Majid; Hosseinzadeh, Simzar; Vakilian, Saeid; Steinbach, Sarah K; Khorramizadeh, Mohammad R; Soleimani, Masoud; Barzin, Jalal

    2017-03-01

    In the embryonic heart, electrical impulses propagate in a unidirectional manner from the sinus venosus and appear to be involved in cardiogenesis. In this work, aligned and random polyaniline/polyetersulfone (PANI/PES) nanofibrous scaffolds doped by Camphor-10-sulfonic acid (β) (CPSA) were fabricated via electrospinning and used to conduct electrical impulses in a unidirectional and multidirectional fashion, respectively. A bioreactor was subsequently engineered to apply electrical impulses to cells cultured on PANI/PES scaffolds. We established cardiovascular disease-specific induced pluripotent stem cells (CVD-iPSCs) from the fibroblasts of patients undergoing cardiothoracic surgeries. The CVD-iPSCs were seeded onto the scaffolds, cultured in cardiomyocyte-inducing factors, and exposed to electrical impulses for 1 h/day, over a 15-day time period in the bioreactor. The application of the unidirectional electrical stimulation to the cells significantly increased the number of cardiac Troponin T (cTnT+) cells in comparison to multidirectional electrical stimulation using random fibrous scaffolds. This was confirmed by real-time polymerase chain reaction for cardiac-related transcription factors (NKX2.5, GATA4, and NPPA) and a cardiac-specific structural gene (TNNT2). Here we report for the first time that applying electrical pulses in a unidirectional manner mimicking the unidirectional wave of electrical stimulation in the heart, could increase the derivation of cardiomyocytes from CVD-iPSCs.

  7. 30 CFR 56.6604 - Precautions during storms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Precautions during storms. 56.6604 Section 56... Extraneous Electricity § 56.6604 Precautions during storms. During the approach and progress of an electrical storm, blasting operations shall be suspended and persons withdrawn from the blast area or to a...

  8. 30 CFR 56.6604 - Precautions during storms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Precautions during storms. 56.6604 Section 56... Extraneous Electricity § 56.6604 Precautions during storms. During the approach and progress of an electrical storm, blasting operations shall be suspended and persons withdrawn from the blast area or to a...

  9. 30 CFR 56.6604 - Precautions during storms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Precautions during storms. 56.6604 Section 56... Extraneous Electricity § 56.6604 Precautions during storms. During the approach and progress of an electrical storm, blasting operations shall be suspended and persons withdrawn from the blast area or to a...

  10. 30 CFR 56.6604 - Precautions during storms.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Precautions during storms. 56.6604 Section 56... Extraneous Electricity § 56.6604 Precautions during storms. During the approach and progress of an electrical storm, blasting operations shall be suspended and persons withdrawn from the blast area or to a...

  11. 30 CFR 56.6604 - Precautions during storms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Precautions during storms. 56.6604 Section 56... Extraneous Electricity § 56.6604 Precautions during storms. During the approach and progress of an electrical storm, blasting operations shall be suspended and persons withdrawn from the blast area or to a...

  12. Cardiac conduction system

    MedlinePlus Videos and Cool Tools

    ... cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components ... the cardiac conduction system's electrical activity in the heart.

  13. Turbulent electrical activity at sharp-edged inexcitable obstacles in a model for human cardiac tissue.

    PubMed

    Majumder, Rupamanjari; Pandit, Rahul; Panfilov, A V

    2014-10-01

    Wave propagation around various geometric expansions, structures, and obstacles in cardiac tissue may result in the formation of unidirectional block of wave propagation and the onset of reentrant arrhythmias in the heart. Therefore, we investigated the conditions under which reentrant spiral waves can be generated by high-frequency stimulation at sharp-edged obstacles in the ten Tusscher-Noble-Noble-Panfilov (TNNP) ionic model for human cardiac tissue. We show that, in a large range of parameters that account for the conductance of major inward and outward ionic currents of the model [fast inward Na(+) current (INa), L-type slow inward Ca(2+) current (ICaL), slow delayed-rectifier current (IKs), rapid delayed-rectifier current (IKr), inward rectifier K(+) current (IK1)], the critical period necessary for spiral formation is close to the period of a spiral wave rotating in the same tissue. We also show that there is a minimal size of the obstacle for which formation of spirals is possible; this size is ∼2.5 cm and decreases with a decrease in the excitability of cardiac tissue. We show that other factors, such as the obstacle thickness and direction of wave propagation in relation to the obstacle, are of secondary importance and affect the conditions for spiral wave initiation only slightly. We also perform studies for obstacle shapes derived from experimental measurements of infarction scars and show that the formation of spiral waves there is facilitated by tissue remodeling around it. Overall, we demonstrate that the formation of reentrant sources around inexcitable obstacles is a potential mechanism for the onset of cardiac arrhythmias in the presence of a fast heart rate.

  14. Interventional electrophysiology and cardiac resynchronization therapy: delivering electrical therapies for heart failure.

    PubMed

    Burkhardt, J David; Wilkoff, Bruce L

    2007-04-24

    Implantable devices have become a readily available option for patients with heart failure. Not only do these patients develop bradycardia and ventricular tachycardia, but their ventricular dysfunction can often improve with cardiac resynchronization therapy. However, this is a complex and rapidly developing clinical science for which the physician chooses techniques and selects patients on the basis of the results of clinical trials, clinical experience, and rapidly evolving tools. The results depend on the interplay of these complex variables. Placement of the left ventricular lead has forced the device physician to develop new skills and/or interdisciplinary relationships with physicians with vascular intervention, imaging, and surgical skills. Familiarity with the cardiac venous anatomy, occlusive venography, venoplasty, guide wire tools, guiding catheters, stenting, and new intracardiac visualization and magnetic intracardiac lead positioning tools are examples of just a few of the novel skills that are useful in the delivery of cardiac resynchronization therapy. Beyond implantation, these patients and devices require specialized follow-up with continued medical therapy and echo-guided adjustments of device programming. Finally, there are ongoing controversies and many as yet unanswered questions that are the subject of ongoing and planned clinical trials.

  15. Geomagnetic storms: historical perspective to modern view

    NASA Astrophysics Data System (ADS)

    Lakhina, Gurbax S.; Tsurutani, Bruce T.

    2016-12-01

    The history of geomagnetism is more than 400 years old. Geomagnetic storms as we know them were discovered about 210 years ago. There has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs, and concomitant magnetic storms in recent times. Magnetic storms are the most important component of space weather effects on Earth. We give an overview of the historical aspects of geomagnetic storms and the progress made during the past two centuries. Super magnetic storms can cause life-threatening power outages and satellite damage, communication failures and navigational problems. The data for such super magnetic storms that occurred in the last 50 years during the space era is sparce. Research on historical geomagnetic storms can help to create a database for intense and super magnetic storms. New knowledge of interplanetary and solar causes of magnetic storms gained from spaceage observations will be used to review the super magnetic storm of September 1-2, 1859. We discuss the occurrence probability of such super magnetic storms, and the maximum possible intensity for the effects of a perfect ICME: extreme super magnetic storm, extreme magnetospheric compression, and extreme magnetospheric electric fields.

  16. Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement

    NASA Astrophysics Data System (ADS)

    Soukup, Ladislav; Vondra, Vlastimil; Viščor, Ivo; Jurák, Pavel; Halámek, Josef

    2013-04-01

    The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

  17. Nanosecond pulsed platelet-rich plasma (nsPRP) improves mechanical and electrical cardiac function following myocardial reperfusion injury.

    PubMed

    Hargrave, Barbara; Varghese, Frency; Barabutis, Nektarios; Catravas, John; Zemlin, Christian

    2016-02-01

    Ischemia and reperfusion (I/R) of the heart is associated with biochemical and ionic changes that result in cardiac contractile and electrical dysfunction. In rabbits, platelet-rich plasma activated using nanosecond pulsed electric fields (nsPRP) has been shown to improve left ventricular pumping. Here, we demonstrate that nsPRP causes a similar improvement in mouse left ventricular function. We also show that nsPRP injection recovers electrical activity even before reperfusion begins. To uncover the mechanism of nsPRP action, we studied whether the enhanced left ventricular function in nsPRP rabbit and mouse hearts was associated with increased expression of heat-shock proteins and altered mitochondrial function under conditions of oxidative stress. Mouse hearts underwent 30 min of global ischemia and 1 h of reperfusion in situ. Rabbit hearts underwent 30 min of ischemia in vivo and were reperfused for 14 days. Hearts treated with nsPRP expressed significantly higher levels of Hsp27 and Hsp70 compared to hearts treated with vehicle. Also, pretreatment of cultured H9c2 cells with nsPRP significantly enhanced the "spare respiratory capacity (SRC)" also referred to as "respiratory reserve capacity" and ATP production in response to the uncoupler FCCP. These results suggest a cardioprotective effect of nsPRP on the ischemic heart during reperfusion.

  18. Influence of heart motion on cardiac output estimation by means of electrical impedance tomography: a case study.

    PubMed

    Proença, Martin; Braun, Fabian; Rapin, Michael; Solà, Josep; Adler, Andy; Grychtol, Bartłomiej; Bohm, Stephan H; Lemay, Mathieu; Thiran, Jean-Philippe

    2015-06-01

    Electrical impedance tomography (EIT) is a non-invasive imaging technique that can measure cardiac-related intra-thoracic impedance changes. EIT-based cardiac output estimation relies on the assumption that the amplitude of the impedance change in the ventricular region is representative of stroke volume (SV). However, other factors such as heart motion can significantly affect this ventricular impedance change. In the present case study, a magnetic resonance imaging-based dynamic bio-impedance model fitting the morphology of a single male subject was built. Simulations were performed to evaluate the contribution of heart motion and its influence on EIT-based SV estimation. Myocardial deformation was found to be the main contributor to the ventricular impedance change (56%). However, motion-induced impedance changes showed a strong correlation (r = 0.978) with left ventricular volume. We explained this by the quasi-incompressibility of blood and myocardium. As a result, EIT achieved excellent accuracy in estimating a wide range of simulated SV values (error distribution of 0.57 ± 2.19 ml (1.02 ± 2.62%) and correlation of r = 0.996 after a two-point calibration was applied to convert impedance values to millilitres). As the model was based on one single subject, the strong correlation found between motion-induced changes and ventricular volume remains to be verified in larger datasets.

  19. Spatiotemporal Regulation of an Hcn4 Enhancer Defines a Role for Mef2c and HDACs in Cardiac Electrical Patterning

    PubMed Central

    Vedantham, Vasanth; Evangelista, Melissa; Huang, Yu; Srivastava, Deepak

    2012-01-01

    Regional differences in cardiomyocyte automaticity permit the sinoatrial node (SAN) to function as the leading cardiac pacemaker and the atrioventricular (AV) junction as a subsidiary pacemaker. The regulatory mechanisms controlling the distribution of automaticity within the heart are not understood. To understand regional variation in cardiac automaticity, we carried out an in vivo analysis of cis-regulatory elements that control expression of the hyperpolarization-activated cyclic-nucleotide gated ion channel 4 (Hcn4). Using transgenic mice, we found that spatial and temporal patterning of Hcn4 expression in the AV conduction system required cis-regulatory elements with multiple conserved fragments. One highly conserved region, which contained a myocyte enhancer factor 2C (Mef2C) binding site previously described in vitro, induced reporter expression specifically in the embryonic non-chamber myocardium and the postnatal AV bundle in a Mef2c-dependent manner in vivo. Inhibition of histone deacetylase (HDAC) activity in cultured transgenic embryos showed expansion of reporter activity to working myocardium. In adult animals, hypertrophy induced by transverse aortic constriction, which causes translocation of HDACs out of the nucleus, resulted in ectopic activation of the Hcn4 enhancer in working myocardium, recapitulating pathological electrical remodeling. These findings reveal mechanisms that control the distribution of automaticity among cardiomyocytes during development and in response to stress. PMID:23085412

  20. Deletion of Kvβ1.1 subunit leads to electrical and haemodynamic changes causing cardiac hypertrophy in female murine hearts

    PubMed Central

    Tur, Jared; Chapalamadugu, Kalyan C.; Padawer, Timothy; Badole, Sachin L.; Kilfoil, Peter J.; Bhatnagar, Aruni; Tipparaju, Srinivas M.

    2016-01-01

    Cardiovascular disease is the leading cause of death and debility in women in the USA, and cardiac arrhythmias are a major concern. Voltage-gated potassium (Kv) channels along with the binding partners; Kvβ subunits are major regulators of the action potential (AP) shape and duration (APD). The regulation of Kv channels by the Kvβ1 subunit is unknown in female hearts. In the present study, we hypothesized that the Kvβ1 subunit is an important regulator of female cardiac physiology. To test this hypothesis, we ablated (knocked out; KO) the KCNAB1 isoform 1 (Kvβ1.1) subunit in mice and evaluated cardiac function and electrical activity by using ECG, monophasic action potential recordings and echocardiography. Our results showed that the female Kvβ1.1 KO mice developed cardiac hypertrophy, and the hearts were structurally different, with enlargement and increased area. The electrical derangements caused by Kvβ1.1 KO in female mice included long QTc and QRS intervals along with increased APD (APD20–90% repolarization). The male Kvβ1.1 KO mice did not develop cardiac hypertrophy, but they showed long QTc and prolonged APD. Molecular analysis showed that several genes that support cardiac hypertrophy were significantly altered in Kvβ1.1 KO female hearts. In particular, myosin heavy chain αexpression was significantly elevated in Kvβ1.1 KO mouse heart. Using a small interfering RNA strategy, we identified that knockdown of Kvβ1 increases myosin heavy chain αexpression in H9C2 cells. Collectively, changes in molecular and cell signalling pathways clearly point towards a distinct electrical and structural remodelling consistent with cardiac hypertrophy in the Kvβ1.1 KO female mice. PMID:27038296

  1. Why QRS Duration Should Be Replaced by Better Measures of Electrical Activation to Improve Patient Selection for Cardiac Resynchronization Therapy.

    PubMed

    Engels, Elien B; Mafi-Rad, Masih; van Stipdonk, Antonius M W; Vernooy, Kevin; Prinzen, Frits W

    2016-08-01

    Cardiac resynchronization therapy (CRT) is a well-known treatment modality for patients with a reduced left ventricular ejection fraction accompanied by a ventricular conduction delay. However, a large proportion of patients does not benefit from this therapy. Better patient selection may importantly reduce the number of non-responders. Here, we review the strengths and weaknesses of the electrocardiogram (ECG) markers currently being used in guidelines for patient selection, e.g., QRS duration and morphology. We shed light on the current knowledge on the underlying electrical substrate and the mechanism of action of CRT. Finally, we discuss potentially better ECG-based biomarkers for CRT candidate selection, of which the vectorcardiogram may have high potential.

  2. Effect of electric and magnetic fields near an HVDC converter terminal on implanted cardiac pacemakers. Final report

    SciTech Connect

    Frazier, M.J.

    1980-08-01

    The electromagnetic fields associated with HVDC converters and transmission lines constitute a unique environment for persons with implanted cardiac pacemakers. A measurement program has been conducted to assess the potential interfering effects of these harmonically rich fields on implanted pacemakers. The experimental procedures that were employed take into account the combined effects of the electric and magnetic fields. The effect of the resulting body current on the response of six pacemakers was assessed in the laboratory, using a previously developed model to relate body current to pacemaker pickup voltage. The results show that R-wave pacemaker reversion can be expected at some locations within the converter facility, but that a large safety margin for unperturbed pacemaker operation exists beneath the transmission lines.

  3. Fluorescence imaging of electrical activity in cardiac cells using an all-solid-state system.

    PubMed

    Entcheva, Emilia; Kostov, Yordan; Tchernev, Elko; Tung, Leslie

    2004-02-01

    Tracking spatial and temporal determinants of cardiac arrhythmogenesis at the cellular level presents challenges to the optical mapping techniques employed. In this paper, we describe a compact system combining two nontraditional low-cost solutions for excitation light sources and emission filters in fluorescence measurements of transmembrane potentials, Vm, or intracellular calcium, [Ca2+]i in cardiac cell networks. This is the first reported use of high-power blue and green light emitting diodes (LEDs), to excite cell monolayers stained with Vm - (di-8-ANEPPS) or [Ca2+]i - (Fluo-3) sensitive dyes. In addition, we use simple techniques for fabrication of suitable thin emission filters with uniform properties, no auto-fluorescence, high durability and good flexibility for imaging Vm or [Ca2+]i. The battery-operated LEDs and the fabricated emission filters, integrated with a fiber-optic system for contact fluorescence imaging, were used as tools to characterize conduction velocity restitution at the macro-scale. The versatility of the LEDs for illumination is further emphasized through 1) demonstration of their usage for epi-illumination recordings at the single-cell level, and 2) demonstration of their unique high-frequency light modulation ability. The LEDs showed excellent stability as excitation light sources for fluorescence measurements; acceptable signal-to-noise ratio and negligible cell photodamage and indicator dye photobleaching were observed.

  4. Cardiac catheterization

    MedlinePlus

    Catheterization - cardiac; Heart catheterization; Angina - cardiac catheterization; CAD - cardiac catheterization; Coronary artery disease - cardiac catheterization; Heart valve - cardiac catheterization; Heart failure - ...

  5. Quantifying Power Grid Risk from Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Homeier, N.; Wei, L. H.; Gannon, J. L.

    2012-12-01

    We are creating a statistical model of the geophysical environment that can be used to quantify the geomagnetic storm hazard to power grid infrastructure. Our model is developed using a database of surface electric fields for the continental United States during a set of historical geomagnetic storms. These electric fields are derived from the SUPERMAG compilation of worldwide magnetometer data and surface impedances from the United States Geological Survey. This electric field data can be combined with a power grid model to determine GICs per node and reactive MVARs at each minute during a storm. Using publicly available substation locations, we derive relative risk maps by location by combining magnetic latitude and ground conductivity. We also estimate the surface electric fields during the August 1972 geomagnetic storm that caused a telephone cable outage across the middle of the United States. This event produced the largest surface electric fields in the continental U.S. in at least the past 40 years.

  6. Evaluation of the effects of electric fields on implanted cardiac pacemakers. Final report

    SciTech Connect

    Moss, A.J.; Carstensen, E.

    1985-02-01

    The effects of extra high voltage (EHV) transmission line electric fields on pacemaker function were evaluated in 11 patients with seven different implanted pacemaker models from four manufacturers. Alteration in pacemaker function was demonstrated in five unipolar units (three different models) from two manufacturers during exposure to electric fields ranging from 2 to 9 kV/m, with total body currents from 47 to 175 ..mu..A. These electric fields and body currents are representative of values that can be encountered by individuals standing beneath EHV transmission lines. Transient alterations in pacemaker function observed in this study included inappropriate triggered activity, inhibition of impulse generation, reduction in rate, and reversion from demand to asynchronous mode. Electromagnetic interference from high voltage transmission lines can induce alterations in pacemaker function in certain designs of these devices. However, pacemaker manufacturers can incorporate appropriate circuits in the pacemaker design to eliminate this problem. 8 references.

  7. Thermal--electrical finite element modelling for radio frequency cardiac ablation: effects of changes in myocardial properties.

    PubMed

    Tungjitkusolmun, S; Woo, E J; Cao, H; Tsai, J Z; Vorperian, V R; Webster, J G

    2000-09-01

    Finite element (FE) analysis has been utilised as a numerical tool to determine the temperature distribution in studies of radio frequency (RF) cardiac ablation. However, none of the previous FE analyses clarified such computational aspects as software requirements, computation time or convergence test. In addition, myocardial properties included in the previous models vary greatly. A process of FE modelling of a system that included blood, myocardium, and an ablation catheter with a thermistor embedded at the tip is described. The bio-heat equation is solved to determine the temperature distribution in myocardium using a commercial software application (ABAQUS). A Cauchy convergence test (epsilon = 0.1 degree C) was performed and it is concluded that the optimal number of elements for the proposed system is 24610. The effects of changes in myocardial properties (+/- 50% electric conductivity, +100%/-50% thermal conductivity, and +100%/-50% specific heat capacity) in both power-controlled (PCRFA) and temperature-controlled RF ablation (TCRFA) were studied. Changes in myocardial properties affect the results of the FE analyses of PCRFA more than those of TCRFA, and the maximum changes in lesion volumes were -58.6% (-50% electric conductivity), -60.7% (+100% thermal conductivity), and +43.2% (-50% specific heat).

  8. The Electric Fields and Waves (EFW) Instrument on the Radiation Belt Storm Probes: Science Operations Center, Operational Modes, and Data Products

    NASA Astrophysics Data System (ADS)

    Bonnell, J. W.; Wygant, J. R.; Ergun, R. E.; Schroeder, P. C.; Rachelson, W.; Tao, J.; Vernetti, J.; Mozer, F.; Kersten, K.; Breneman, A. W.; Kletzing, C.; Bounds, S. R.; Kurth, W. S.; Hospodarsky, G. B.; MacDowall, R. J.; Smith, C. W.

    2012-12-01

    The Electric Field and Waves (EFW) instrument on the NASA Radiation Belt Storm Probes (RBSP) observatories provides measurement of 3D DC and AC E-fields, as well as 3D AC magnetic fields as provided on board from the EMFISIS tri-axial searchcoil magnetometer (MSC). Two 100-m tip-to-tip spin plane and 12 to 14-m tip-to-tip axial E-field antennas are deployed on each of the two RBSP observatories, with all instrument operations controlled on board via the EFW Instrument Data Processing Unit (IDPU). Both continuous waveform and spectral data products from DC up to 8 kHz, as well as high-rate burst waveforms (E-field and interferometric modes) are produced on-board through a highly-configurable digital signal processing system. A large-capacity waveform burst memory (32 GB) with human-in-the-loop playback selection is also included in the EFW instrument, allowing for days to tens of days of lookback and playback of selected time intervals of burst data. EFW also provides higher-frequency 3D E-field signals to the EMFISIS suite, providing waveform coverage up to 12 kHz and spectral coverage to over 400 kHz. A description of all the EFW operational modes and data products is presented. Access tot he ISTP-compliant CDF datasets served from the primary EFW Science Operations Center (SOC) at the University of California, Berkeley is shown, along with support for data acquisition and analysis under the IDL THEMIS Data Analysis Software (TDAS) and Science Data Tool (SDT) packages.

  9. Spatial heterogeneity of transmembrane potential responses of single guinea-pig cardiac cells during electric field stimulation

    PubMed Central

    Sharma, Vinod; Tung, Leslie

    2002-01-01

    Changes in transmembrane voltage (Vm) of cardiac cells during electric field stimulation have a complex spatial- and time-dependent behaviour that differs significantly from electrical stimulation of space-clamped membranes by current pulses. A multisite optical mapping system was used to obtain 17 or 25 μm resolution maps of Vm along the long axis of guinea-pig ventricular cells (n = 57) stained with voltage-sensitive dye (di-8-ANEPPS) and stimulated longitudinally with uniform electric field (2, 5 or 10 ms, 3–62 V cm−1) pulses (n = 201). The initial polarizations of Vm responses (Vmr) varied linearly along the cell length and reversed symmetrically upon field reversal. The remainder of the Vm responses had parallel time courses among the recording sites, revealing a common time-varying signal component (Vms). Vms was depolarizing for pulses during rest and hyperpolarizing for pulses during the early plateau phase. Vms varied in amplitude and time course with increasing pulse amplitude. Four types of plateau response were observed, with transition points between the different responses occurring when the maximum polarization at the ends of the cell reached values estimated as 60, 110 and 220 mV. Among the cells that had a polarization change of > 200 mV at their ends (for fields > 45 V cm−1), some (n = 17/25) had non-parallel time courses among Vm recordings of the various sites. This implied development of an intracellular field (Ei) that was found to increase exponentially with time (τ = 7.2 ± 3.2 ms). Theoretical considerations suggest that Vms represents the intracellular potential (φi) as well as the average polarization of the cell, and that Vmr is the manifestation of the extracellular potential gradient resulting from the field stimulus. For cells undergoing field stimulation, φi acts as the cellular physiological state variable and substitutes for Vm, which is the customary variable for space-clamped membranes. PMID:12122146

  10. Correlations between the Signal Complexity of Cerebral and Cardiac Electrical Activity: A Multiscale Entropy Analysis

    PubMed Central

    Lin, Pei-Feng; Lo, Men-Tzung; Tsao, Jenho; Chang, Yi-Chung; Lin, Chen; Ho, Yi-Lwun

    2014-01-01

    The heart begins to beat before the brain is formed. Whether conventional hierarchical central commands sent by the brain to the heart alone explain all the interplay between these two organs should be reconsidered. Here, we demonstrate correlations between the signal complexity of brain and cardiac activity. Eighty-seven geriatric outpatients with healthy hearts and varied cognitive abilities each provided a 24-hour electrocardiography (ECG) and a 19-channel eye-closed routine electroencephalography (EEG). Multiscale entropy (MSE) analysis was applied to three epochs (resting-awake state, photic stimulation of fast frequencies (fast-PS), and photic stimulation of slow frequencies (slow-PS)) of EEG in the 1–58 Hz frequency range, and three RR interval (RRI) time series (awake-state, sleep and that concomitant with the EEG) for each subject. The low-to-high frequency power (LF/HF) ratio of RRI was calculated to represent sympatho-vagal balance. With statistics after Bonferroni corrections, we found that: (a) the summed MSE value on coarse scales of the awake RRI (scales 11–20, RRI-MSE-coarse) were inversely correlated with the summed MSE value on coarse scales of the resting-awake EEG (scales 6–20, EEG-MSE-coarse) at Fp2, C4, T6 and T4; (b) the awake RRI-MSE-coarse was inversely correlated with the fast-PS EEG-MSE-coarse at O1, O2 and C4; (c) the sleep RRI-MSE-coarse was inversely correlated with the slow-PS EEG-MSE-coarse at Fp2; (d) the RRI-MSE-coarse and LF/HF ratio of the awake RRI were correlated positively to each other; (e) the EEG-MSE-coarse at F8 was proportional to the cognitive test score; (f) the results conform to the cholinergic hypothesis which states that cognitive impairment causes reduction in vagal cardiac modulation; (g) fast-PS significantly lowered the EEG-MSE-coarse globally. Whether these heart-brain correlations could be fully explained by the central autonomic network is unknown and needs further exploration. PMID:24498375

  11. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M.

    1997-01-01

    Geomagnetic storms, induced by solar activity, pose significant hazards to satellites, electrical power distribution systems, radio communications, navigation, and geophysical surveys. Strong storms can expose astronauts and crews of high-flying aircraft to dangerous levels of radiation. Economic losses from recent geomagnetic storms have run into hundreds of millions of dollars. With the U.S. Geological Survey (USGS) as the lead agency, an international network of geomagnetic observatories monitors the onset of solar-induced storms and gives warnings that help diminish losses to military and commercial operations and facilities.

  12. Vagal control of cardiac electrical activity and wall motion during ventricular fibrillation in large animals.

    PubMed

    Naggar, Isaac; Nakase, Ko; Lazar, Jason; Salciccioli, Louis; Selesnick, Ivan; Stewart, Mark

    2014-07-01

    Vagal inputs control pacemaking and conduction systems in the heart. Anatomical evidence suggests a direct ventricular action, but functional evidence that separates direct and indirect (via the conduction system) vagal actions is less well established. We studied vagus nerve stimulation (VNS) during sinus rhythm and ventricular fibrillation (VF) in pigs and sheep to determine: 1) the range of unilateral and bilateral actions (inotropic and chronotropic) and 2) whether VNS alters left ventricular motion and/or electrical activity during VF, a model of abnormal electrical conduction of the left ventricle that excludes sinus and atrioventricular nodal function. Adult pigs (N=8) and sheep (N=10) were anesthetized with urethane and mechanically ventilated. VNS was performed in animals at 1, 2, 5, 10, 20, 50, and 100Hz for 20s. VF was induced with direct current to the ventricles or occlusion of the left anterior descending coronary artery. In 4 pigs and 3 sheep, left ventricular wall motion was assessed from endocardial excursion in epicardial echocardiography. In sheep and pigs, the best frequency among those tested for VNS during sinus rhythm to produce sustained electrical and mechanical ventricular standstill was 50Hz for unilateral or bilateral stimulation. When applied during VF, bilateral VNS increased the variability of the dominant VF frequency, indicating a direct impact on the excitability of ventricular myocytes, and decreased endocardial excursion by more than 50% during VF. We conclude that the vagus nerve directly modulates left ventricular function independently from its effects on the conduction system.

  13. Electronegative LDL-mediated cardiac electrical remodeling in a rat model of chronic kidney disease

    PubMed Central

    Lee, An-Sheng; Chen, Wei-Yu; Chan, Hua-Chen; Chung, Ching-Hu; Peng, Hsien-Yu; Chang, Chia-Ming; Su, Ming-Jai; Chen, Chu-Huang; Chang, Kuan-Cheng

    2017-01-01

    The mechanisms underlying chronic kidney disease (CKD)–associated higher risks for life-threatening ventricular tachyarrhythmias remain poorly understood. In rats subjected to unilateral nephrectomy (UNx), we examined cardiac electrophysiological remodeling and relevant mechanisms predisposing to ventricular arrhythmias. Adult male Sprague-Dawley rats underwent UNx (n = 6) or sham (n = 6) operations. Eight weeks later, the UNx group had higher serum blood urea nitrogen and creatinine levels and a longer electrocardiographic QTc interval than did the sham group. Patch-clamp studies revealed epicardial (EPI)-predominant prolongation of the action potential duration (APD) at 50% and 90% repolarization in UNx EPI cardiomyocytes compared to sham EPI cardiomyocytes. A significant reduction of the transient outward potassium current (Ito) in EPI but not in endocardial (ENDO) cardiomyocytes of UNx rats led to a decreased transmural gradient of Ito. The reduction of Ito currents in UNx EPI cardiomyocytes was secondary to downregulation of KChIP2 but not Kv4.2, Kv4.3, and Kv1.4 protein expression. Incubation of plasma electronegative low-density lipoprotein (LDL) from UNx rats with normal EPI and ENDO cardiomyocytes recapitulated the electrophysiological phenotype of UNx rats. In conclusion, CKD disrupts the physiological transmural gradient of Ito via downregulation of KChIP2 proteins in the EPI region, which may promote susceptibility to ventricular tachyarrhythmias. Electronegative LDL may underlie downregulation of KChIP2 in CKD. PMID:28094801

  14. Current understanding of magnetic storms: Storm-substorm relationships

    SciTech Connect

    Kamide, Y.; Gonzalez, W.D.; Baumjohann, W.; Daglis, I.A.; Grande, M.; Joselyn, J.A.; Singer, H.J.; McPherron, R.L.; Phillips, J.L.; Reeves, E.G.; Rostoker, G.; Sharma, A.S.; Tsurutani, B.T.

    1998-08-01

    This paper attempts to summarize the current understanding of the storm/substorm relationship by clearing up a considerable amount of controversy and by addressing the question of how solar wind energy is deposited into and is dissipated in the constituent elements that are critical to magnetospheric and ionospheric processes during magnetic storms. (1) Four mechanisms are identified and discussed as the primary causes of enhanced electric fields in the interplanetary medium responsible for geomagnetic storms. It is pointed out that in reality, these four mechanisms, which are not mutually exclusive, but interdependent, interact differently from event to event. Interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) are found to be the primary phenomena responsible for the main phase of geomagnetic storms. The other two mechanisms, i.e., HILDCAA (high-intensity, long-duration, continuous auroral electrojet activity) and the so-called Russell-McPherron effect, work to make the ICME and CIR phenomena more geoeffective. The solar cycle dependence of the various sources in creating magnetic storms has yet to be quantitatively understood. (2) A serious controversy exists as to whether the successive occurrence of intense substorms plays a direct role in the energization of ring current particles or whether the enhanced electric field associated with southward IMF enhances the effect of substorm expansions. While most of the {ital Dst} variance during magnetic storms can be solely reproduced by changes in the large-scale electric field in the solar wind and the residuals are uncorrelated with substorms, recent satellite observations of the ring current constituents during the main phase of magnetic storms show the importance of ionospheric ions. This implies that ionospheric ions, which are associated with the frequent occurrence of intense substorms, are accelerated upward along magnetic field lines, contributing to the energy density of

  15. Electrical injury

    MedlinePlus

    ... damage, especially to the heart, muscles, or brain. Electric current can cause injury in three ways: Cardiac arrest ... How long you were in contact with the electricity How the electricity moved through your body Your ...

  16. [Cardiac manifestations of mitochondrial diseases].

    PubMed

    Ritzenthaler, Thomas; Luis, David; Hullin, Thomas; Fayssoil, Abdallah

    2015-05-01

    Mitochondrial diseases are multi-system disorders in relation with mitochondrial DNA and/or nuclear DNA abnormalities. Clinical pictures are heterogeneous, involving endocrine, cardiac, neurologic or sensory systems. Cardiac involvements are morphological and electrical disturbances. Prognosis is worsened in case of cardiac impairment. Treatments are related to the type of cardiac dysfunction including medication or pacemaker implantation.

  17. A coupled 3D-1D numerical monodomain solver for cardiac electrical activation in the myocardium with detailed Purkinje network

    NASA Astrophysics Data System (ADS)

    Vergara, Christian; Lange, Matthias; Palamara, Simone; Lassila, Toni; Frangi, Alejandro F.; Quarteroni, Alfio

    2016-03-01

    We present a model for the electrophysiology in the heart to handle the electrical propagation through the Purkinje system and in the myocardium, with two-way coupling at the Purkinje-muscle junctions. In both the subproblems the monodomain model is considered, whereas at the junctions a resistor element is included that induces an orthodromic propagation delay from the Purkinje network towards the heart muscle. We prove a sufficient condition for convergence of a fixed-point iterative algorithm to the numerical solution of the coupled problem. Numerical comparison of activation patterns is made with two different combinations of models for the coupled Purkinje network/myocardium system, the eikonal/eikonal and the monodomain/monodomain models. Test cases are investigated for both physiological and pathological activation of a model left ventricle. Finally, we prove the reliability of the monodomain/monodomain coupling on a realistic scenario. Our results underlie the importance of using physiologically realistic Purkinje-trees with propagation solved using the monodomain model for simulating cardiac activation.

  18. Regulation of Ca2+ and electrical alternans in cardiac myocytes: Role of CaMKII and repolarizing currents

    PubMed Central

    Livshitz, Leonid M.; Rudy, Yoram

    2007-01-01

    Alternans of cardiac repolarization is associated with arrhythmias and sudden death. At the cellular level, alternans involves beat-to-beat oscillation of the action potential (AP) and possibly Ca2+ transient (CaT). Because of experimental difficulty in independently controlling the Ca2+ and electrical subsystems, mathematical modelling provides additional insights into mechanisms and causality. Pacing protocols were conducted in a canine ventricular myocyte model with the following results: 1. (I) CaT alternans results from refractoriness of the SR Ca2+ release system; alternation of the L-type calcium current (ICa(L)) has a negligible effect; (II) CaT-AP coupling during late AP occurs through the sodium-calcium exchanger (INaCa) and underlies APD alternans; (III) Increased Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity extends the range of CaT and APD alternans to slower frequencies and increases alternans magnitude; its decrease suppresses CaT and APD alternans, exerting an antiarrhythmic effect; (IV). Increase of the rapid delayed rectifier current (IKr) also suppresses APD alternans, but without suppressing CaT alternans. Thus, CaMKII inhibition eliminates APD alternans by eliminating its cause (CaT alternans), while IKr enhancement does so by weakening CaT-APD coupling. The simulations identify combined CaMKII inhibition and IKr enhancement as a possible antiar-rhythmic intervention. PMID:17277017

  19. The influence of anatomical and physiological parameters on the interference voltage at the input of unipolar cardiac pacemakers in low frequency electric fields.

    PubMed

    Joosten, S; Pammler, K; Silny, J

    2009-02-07

    The problem of electromagnetic interference of electronic implants such as cardiac pacemakers has been well known for many years. An increasing number of field sources in everyday life and occupational environment leads unavoidably to an increased risk for patients with electronic implants. However, no obligatory national or international safety regulations exist for the protection of this patient group. The aim of this study is to find out the anatomical and physiological worst-case conditions for patients with an implanted pacemaker adjusted to unipolar sensing in external time-varying electric fields. The results of this study with 15 volunteers show that, in electric fields, variation of the interference voltage at the input of a cardiac pacemaker adds up to 200% only because of individual factors. These factors should be considered in human studies and in the setting of safety regulations.

  20. Iron Deposition following Chronic Myocardial Infarction as a Substrate for Cardiac Electrical Anomalies: Initial Findings in a Canine Model

    PubMed Central

    Wang, Xunzhang; Yang, Hsin-Jung; Tang, Richard L. Q.; Thajudeen, Anees; Shehata, Michael; Amorn, Allen M.; Liu, Enzhao; Stewart, Brian; Bennett, Nathan; Harlev, Doron; Tsaftaris, Sotirios A.; Jackman, Warren M.; Chugh, Sumeet S.; Dharmakumar, Rohan

    2013-01-01

    Purpose Iron deposition has been shown to occur following myocardial infarction (MI). We investigated whether such focal iron deposition within chronic MI lead to electrical anomalies. Methods Two groups of dogs (ex-vivo (n = 12) and in-vivo (n = 10)) were studied at 16 weeks post MI. Hearts of animals from ex-vivo group were explanted and sectioned into infarcted and non-infarcted segments. Impedance spectroscopy was used to derive electrical permittivity () and conductivity (). Mass spectrometry was used to classify and characterize tissue sections with (IRON+) and without (IRON-) iron. Animals from in-vivo group underwent cardiac magnetic resonance imaging (CMR) for estimation of scar volume (late-gadolinium enhancement, LGE) and iron deposition (T2*) relative to left-ventricular volume. 24-hour electrocardiogram recordings were obtained and used to examine Heart Rate (HR), QT interval (QT), QT corrected for HR (QTc) and QTc dispersion (QTcd). In a fraction of these animals (n = 5), ultra-high resolution electroanatomical mapping (EAM) was performed, co-registered with LGE and T2* CMR and were used to characterize the spatial locations of isolated late potentials (ILPs). Results Compared to IRON- sections, IRON+ sections had higher, but no difference in. A linear relationship was found between iron content and (p<0.001), but not (p = 0.34). Among two groups of animals (Iron (<1.5%) and Iron (>1.5%)) with similar scar volumes (7.28%±1.02% (Iron (<1.5%)) vs 8.35%±2.98% (Iron (>1.5%)), p = 0.51) but markedly different iron volumes (1.12%±0.64% (Iron (<1.5%)) vs 2.47%±0.64% (Iron (>1.5%)), p = 0.02), QT and QTc were elevated and QTcd was decreased in the group with the higher iron volume during the day, night and 24-hour period (p<0.05). EAMs co-registered with CMR images showed a greater tendency for ILPs to emerge from scar regions with iron versus without iron. Conclusion The electrical behavior of infarcted hearts with iron appears to

  1. [Cardiac electric field at the period of depolarization and repolarization of the frog heart ventricle].

    PubMed

    Vaĭkshnoraĭte, M A; Belogolova, A S; Vitiazev, V A; Azarov, Ia E; Shmakov, D N

    2008-01-01

    Multichannel mapping of electrical field on heart ventricle epicardium and the body surface in frogs Rana esculenta and Rana temporaria was performed at periods of the ventricular myocardium depolarization and repolarization. The zone of the epicardium early depolarization is located on epicardium of the ventricle base posterior wall, while the late depolarization zone--on its apex and on the base anterior wall. The total vector of sequence of the ventricle epicardium depolarization is directed from the base to the apex. The zone of the early repolarization is located in the apical area, while that of the late one--in the area of the base. On the frog body surface the cardioelectric field with the cranial zone of negative and the caudal zone of positive potentials is formed before the appearance of the QRS complex on ECG. At the period of the heart ventricle repolarization the zone of the cardioelectric field negative potentials is located in the cranial, while that of the positive ones--in the body surface caudal parts. The cardioelectric field on the frog body surface at the periods of depolarization and repolarization of the ventricle myocardium reflects adequately the projection of sequence of involvement with excitation and of distribution of potentials on epicardium.

  2. Propagation of Electrical Excitation in a Ring of Cardiac Cells: A Computer Simulation Study

    NASA Technical Reports Server (NTRS)

    Kogan, B. Y.; Karplus, W. J.; Karpoukhin, M. G.; Roizen, I. M.; Chudin, E.; Qu, Z.

    1996-01-01

    The propagation of electrical excitation in a ring of cells described by the Noble, Beeler-Reuter (BR), Luo-Rudy I (LR I), and third-order simplified (TOS) mathematical models is studied using computer simulation. For each of the models it is shown that after transition from steady-state circulation to quasi-periodicity achieved by shortening the ring length (RL), the action potential duration (APD) restitution curve becomes a double-valued function and is located below the original ( that of an isolated cell) APD restitution curve. The distributions of APD and diastolic interval (DI) along a ring for the entire range of RL corresponding to quasi-periodic oscillations remain periodic with the period slightly different from two RLs. The 'S' shape of the original APD restitution curve determines the appearance of the second steady-state circulation region for short RLs. For all the models and the wide variety of their original APD restitution curves, no transition from quasi-periodicity to chaos was observed.

  3. Intracellular angiotensin-(1–12) changes the electrical properties of intact cardiac muscle

    PubMed Central

    Dell’Itallia, L. J.; Varagic, J.; Ferrario, C. M.

    2016-01-01

    In the present work, the influence of intracellular injection of angiotensin-(1–12) [Ang-(1–12)] on the electrical properties of the intact left ventricle of Wistar Kyoto rats was investigated with electrophysiological methods. Particular attention was given to the role of chymostatin on the effect of the peptide. The results indicated that intra-cellular administration of the peptide elicited a depolarization of the surface cell membrane and an increase of duration of the action potential followed by the generation of early afterdepolarizations. The increment of action potential duration caused by Ang-(1–12) (100 nM) was due to a decrease of total potassium current recorded from single cardiomyocytes using the whole cell configuration of pCAMP. The decrease of potassium current was related to the activation of protein kinase C (PKC) because the specific inhibitor of kinase C, Bis-1 (10−9 M), abolished Ang-(1–12) effects on the potassium current. The question of whether the effect of Ang-(1–12) was related to the formation of Ang II by chymase was investigated. The results revealed that the intracellular administration of chymostatin, a chymase inhibitor (10−9 M) abolished the effect of intracellular Ang-(1–12) on the potassium current. Moreover, intracellular Ang II (100 nM), by itself, reduced the potassium current, an effect decreased by intracellular valsartan (100 nM). Valsartan (10–9 M) dialyzed into the cell abolished the effect of Ang-(1–12) (100 nM). These observations demonstrate that the effect of Ang-(1–12) on potassium current was related to the formation of Ang II and that the peptide has arrhythmogenic properties. PMID:27590241

  4. 30 CFR 57.6604 - Precautions during storms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Precautions during storms. 57.6604 Section 57... Extraneous Electricity-Surface and Underground § 57.6604 Precautions during storms. During the approach and progress of an electrical storm— (a) Surface blasting operations shall be suspended and persons...

  5. 30 CFR 57.6604 - Precautions during storms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Precautions during storms. 57.6604 Section 57... Extraneous Electricity-Surface and Underground § 57.6604 Precautions during storms. During the approach and progress of an electrical storm— (a) Surface blasting operations shall be suspended and persons...

  6. 30 CFR 57.6604 - Precautions during storms.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Precautions during storms. 57.6604 Section 57... Extraneous Electricity-Surface and Underground § 57.6604 Precautions during storms. During the approach and progress of an electrical storm— (a) Surface blasting operations shall be suspended and persons...

  7. 30 CFR 57.6604 - Precautions during storms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Precautions during storms. 57.6604 Section 57... Extraneous Electricity-Surface and Underground § 57.6604 Precautions during storms. During the approach and progress of an electrical storm— (a) Surface blasting operations shall be suspended and persons...

  8. 30 CFR 57.6604 - Precautions during storms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Precautions during storms. 57.6604 Section 57... Extraneous Electricity-Surface and Underground § 57.6604 Precautions during storms. During the approach and progress of an electrical storm— (a) Surface blasting operations shall be suspended and persons...

  9. Crib death: further support for the concept of fatal cardiac electrical instability as the final common pathway.

    PubMed

    Ottaviani, Giulia; Matturri, Luigi; Rossi, Lino; James, Thomas N

    2003-11-01

    This work intends to be a review of the current status of knowledge on the cardiac conduction system in the crib death as well as remaining challenges, including reflections upon authors' personal works as well as many studies by others. The cardiac conduction system findings of resorptive degeneration, His bundle dispersion, Mahaim fibers, cartilaginous meta-hyperplasia, persistent fetal dispersion, left sided His bundle, hemorrhage of the atrio-ventricular junction, septation of the bifurcation, atrio-ventricular node dispersion, sinus node hypoplasia, Zahn node, His bundle hypoplasia, atrio-ventricular node and His bundle dualism are hereby discussed by the authors. The cardiac hypotheses postulating that crib death could be due to lethal cardiac arrhythmias or heart block were considered of great interest in the 1970s. After a general abandon of the conduction studies in crib death, the cardiac concept of crib death is gathering a renewed interest, as well as the occurrence of infantile junctional tachycardia. Both the morphological and functional derangement underlying crib death remain poorly understood, assuring that it remains to be a major medical and social problem. Despite the non-specificity of most of the cardiac conduction findings in crib death, we believe that they, in association with altered neurovegetative stimuli, could underlie potentially malignant arrhythmias, providing a morphologic support for the cardiac concept of crib death.

  10. In the eye of the storm: iodinated contrast medium induced thyroid storm presenting as cardiopulmonary arrest.

    PubMed

    Alkhuja, Samer; Pyram, Ronald; Odeyemi, Olutunde

    2013-01-01

    The administration of iodinated contrast medium may lead to excess free thyroid hormone release and cause thyroid storm. A woman presented to the emergency department with dyspnea, hemoptysis, and intermittent bilateral lower extremities edema. Physical examination revealed mildly enlarged thyroid. Patient underwent a computed tomography scan of the chest with intravenous iodinated contrast medium to rule out pulmonary embolism, the patient developed a thyroid storm second to iodinated contrast medium injection. Proper treatment was provided and the patient had a good outcome. We present this case of an unusual presentation of a thyroid storm with cardiac arrest. This case illustrates that evaluating thyroid function tests in patients with an enlarged thyroid prior to the administration of iodinated contrast medium could prevent the development of thyroid storm.

  11. Tropical Storm Frances Situation Report, September 7, 2004 (10:00 PM EDT)

    SciTech Connect

    2004-09-07

    The report provides highlights related to impacts of Tropical Storm Frances in the Florida area. Sections on electric information, oil and gas information, storm track, and county outage data are provided.

  12. Beneficial triple-site cardiac resynchronization in a patient supported with an intra-aortic balloon pump for end-stage heart failure

    PubMed Central

    Ciszewski, Jan; Maciąg, Aleksander; Gepner, Katarzyna; Smolis-Bąk, Edyta

    2014-01-01

    The authors present the case of a 62-year-old male patient with an implantable cardioverter-defibrillator and end-stage heart failure supported with an intra-aortic balloon pump. Implantation of a triple-site cardiac resynchronization system and complex heart failure treatment brought a significant improvement, return to home activity and 17-month survival. The patient died due to heart failure aggravation. Within this time he was rehospitalized and successfully treated twice for an electrical storm. PMID:24799927

  13. Beneficial triple-site cardiac resynchronization in a patient supported with an intra-aortic balloon pump for end-stage heart failure.

    PubMed

    Ciszewski, Jan; Maciąg, Aleksander; Gepner, Katarzyna; Smolis-Bąk, Edyta; Sterliński, Maciej

    2014-01-01

    The authors present the case of a 62-year-old male patient with an implantable cardioverter-defibrillator and end-stage heart failure supported with an intra-aortic balloon pump. Implantation of a triple-site cardiac resynchronization system and complex heart failure treatment brought a significant improvement, return to home activity and 17-month survival. The patient died due to heart failure aggravation. Within this time he was rehospitalized and successfully treated twice for an electrical storm.

  14. Transplantation of adipose tissue-derived stem cells improves cardiac contractile function and electrical stability in a rat myocardial infarction model.

    PubMed

    Gautam, Milan; Fujita, Daiki; Kimura, Kazuhiro; Ichikawa, Hinako; Izawa, Atsushi; Hirose, Masamichi; Kashihara, Toshihide; Yamada, Mitsuhiko; Takahashi, Masafumi; Ikeda, Uichi; Shiba, Yuji

    2015-04-01

    The transplantation of adipose tissue-derived stem cells (ADSCs) improves cardiac contractility after myocardial infarction (MI); however, little is known about the electrophysiological consequences of transplantation. The purpose of this study was to clarify whether the transplantation of ADSCs increases or decreases the incidence of ventricular tachyarrhythmias (VT) in a rat model of MI. MI was induced experimentally by permanent occlusion of the left anterior descending artery of Lewis rats. ADSCs were harvested from GFP-transgenic rats, and were cultured until passage four. ADSCs (10×10(6)) resuspended in 100μL saline or pro-survival cocktail (PSC), which enhances cardiac graft survival, were injected directly into syngeneic rat hearts 1week after MI. The recipients of ADSCs suspended in PSC had a larger graft area compared with those receiving ASDCs suspended in saline at 1week post-transplantation (number of graft cells/section: 148.7±10.6 vs. 22.4±3.4, p<0.05, n=5/group). Thereafter, all ADSC recipients were transplanted with ASDCs in PSC. ADSCs were transplanted into infarcted hearts, and the mechanical and electrophysiological functions were assessed. Echocardiography revealed that ADSC recipients had improved contractile function compared with those receiving PSC vehicle (fractional shortening: 21.1±0.9 vs. 14.1±1.2, p<0.05, n≥12/group). Four weeks post-transplantation, VT was induced via in vivo programmed electrical stimulation. The recipients of ADSCs showed a significantly lower incidence of induced VT compared with the control (31.3% vs. 83.3%, p<0.05, n≥12/group). To understand the electrical activity following transplantation, we performed ex vivo optical mapping using a voltage sensitive dye, and found that ADSC transplantation decreased conduction velocity and its dispersion in the peri-infarct area. These results suggest that ADSC transplantation improved cardiac mechanical and electrophysiological functions in subacute MI.

  15. Pacific Northwest Storms Situation Report # 1

    SciTech Connect

    2006-12-15

    Severe wind and snow storms hit the Pacific Northwest region on December 14 – 15, 2006, following severe flooding during the past few days. The severe weather resulted in major power outages through the region. At peak there were 1.8 million customers without power which included BC Hydro in Canada. Currently, there are over 1.5 million outages in the region as a result of the Pacific Northwest Storms. This represents about 42 percent of customers in affected utility service areas in Oregon and Washington. See table below. Because the current wind and snow storms are coming on the heels of extensive flooding in the region, electric utilities are experiencing damage. Wind gusts reached close to 100 mph in some areas of the region. The storm is expected to bring its strong winds and heavy snow into Idaho, Montana and Wyoming Friday and into the weekend. There are currently no reported major impacts to the petroleum and natural gas infrastructure.

  16. Characterizing Extreme Ionospheric Storms

    NASA Astrophysics Data System (ADS)

    Sparks, L.; Komjathy, A.; Altshuler, E.

    2011-12-01

    Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for

  17. Coastal Storm Model.

    DTIC Science & Technology

    1976-04-30

    MILL IBARS I ~ 1022.8. 0 SEA I LND 0’ 100 A-STORM TRACK 200 :km. NORTH; B-STORM TRACK 0_____. T% WO - X00 SHORE SITEI C-STORM TRACK 300 SOU 00 .) -400 0...SCOTIA CANADA PRUF. C. . A. M._KING D PARTMENT IF GFOGRAPHY JR. H. J. SCHOEMAKER _1,NIVELSITY UF NOTT INGHAM . ... W ATFRLOUPKUNDIG LARIORATORIUM TE

  18. Cardiac electrical defects in progeroid mice and Hutchinson-Gilford progeria syndrome patients with nuclear lamina alterations.

    PubMed

    Rivera-Torres, José; Calvo, Conrado J; Llach, Anna; Guzmán-Martínez, Gabriela; Caballero, Ricardo; González-Gómez, Cristina; Jiménez-Borreguero, Luis J; Guadix, Juan A; Osorio, Fernando G; López-Otín, Carlos; Herraiz-Martínez, Adela; Cabello, Nuria; Vallmitjana, Alex; Benítez, Raul; Gordon, Leslie B; Jalife, José; Pérez-Pomares, José M; Tamargo, Juan; Delpón, Eva; Hove-Madsen, Leif; Filgueiras-Rama, David; Andrés, Vicente

    2016-11-15

    Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease caused by defective prelamin A processing, leading to nuclear lamina alterations, severe cardiovascular pathology, and premature death. Prelamin A alterations also occur in physiological aging. It remains unknown how defective prelamin A processing affects the cardiac rhythm. We show age-dependent cardiac repolarization abnormalities in HGPS patients that are also present in the Zmpste24(-/-) mouse model of HGPS. Challenge of Zmpste24(-/-) mice with the β-adrenergic agonist isoproterenol did not trigger ventricular arrhythmia but caused bradycardia-related premature ventricular complexes and slow-rate polymorphic ventricular rhythms during recovery. Patch-clamping in Zmpste24(-/-) cardiomyocytes revealed prolonged calcium-transient duration and reduced sarcoplasmic reticulum calcium loading and release, consistent with the absence of isoproterenol-induced ventricular arrhythmia. Zmpste24(-/-) progeroid mice also developed severe fibrosis-unrelated bradycardia and PQ interval and QRS complex prolongation. These conduction defects were accompanied by overt mislocalization of the gap junction protein connexin43 (Cx43). Remarkably, Cx43 mislocalization was also evident in autopsied left ventricle tissue from HGPS patients, suggesting intercellular connectivity alterations at late stages of the disease. The similarities between HGPS patients and progeroid mice reported here strongly suggest that defective cardiac repolarization and cardiomyocyte connectivity are important abnormalities in the HGPS pathogenesis that increase the risk of arrhythmia and premature death.

  19. Cardiac electrical defects in progeroid mice and Hutchinson–Gilford progeria syndrome patients with nuclear lamina alterations

    PubMed Central

    Rivera-Torres, José; Calvo, Conrado J.; Llach, Anna; Guzmán-Martínez, Gabriela; Caballero, Ricardo; González-Gómez, Cristina; Jiménez-Borreguero, Luis J.; Guadix, Juan A.; Osorio, Fernando G.; López-Otín, Carlos; Herraiz-Martínez, Adela; Cabello, Nuria; Vallmitjana, Alex; Benítez, Raul; Gordon, Leslie B.; Pérez-Pomares, José M.; Tamargo, Juan; Delpón, Eva; Hove-Madsen, Leif; Filgueiras-Rama, David; Andrés, Vicente

    2016-01-01

    Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disease caused by defective prelamin A processing, leading to nuclear lamina alterations, severe cardiovascular pathology, and premature death. Prelamin A alterations also occur in physiological aging. It remains unknown how defective prelamin A processing affects the cardiac rhythm. We show age-dependent cardiac repolarization abnormalities in HGPS patients that are also present in the Zmpste24−/− mouse model of HGPS. Challenge of Zmpste24−/− mice with the β-adrenergic agonist isoproterenol did not trigger ventricular arrhythmia but caused bradycardia-related premature ventricular complexes and slow-rate polymorphic ventricular rhythms during recovery. Patch-clamping in Zmpste24−/− cardiomyocytes revealed prolonged calcium-transient duration and reduced sarcoplasmic reticulum calcium loading and release, consistent with the absence of isoproterenol-induced ventricular arrhythmia. Zmpste24−/− progeroid mice also developed severe fibrosis-unrelated bradycardia and PQ interval and QRS complex prolongation. These conduction defects were accompanied by overt mislocalization of the gap junction protein connexin43 (Cx43). Remarkably, Cx43 mislocalization was also evident in autopsied left ventricle tissue from HGPS patients, suggesting intercellular connectivity alterations at late stages of the disease. The similarities between HGPS patients and progeroid mice reported here strongly suggest that defective cardiac repolarization and cardiomyocyte connectivity are important abnormalities in the HGPS pathogenesis that increase the risk of arrhythmia and premature death. PMID:27799555

  20. Cardiac optogenetics

    PubMed Central

    2013-01-01

    Optogenetics is an emerging technology for optical interrogation and control of biological function with high specificity and high spatiotemporal resolution. Mammalian cells and tissues can be sensitized to respond to light by a relatively simple and well-tolerated genetic modification using microbial opsins (light-gated ion channels and pumps). These can achieve fast and specific excitatory or inhibitory response, offering distinct advantages over traditional pharmacological or electrical means of perturbation. Since the first demonstrations of utility in mammalian cells (neurons) in 2005, optogenetics has spurred immense research activity and has inspired numerous applications for dissection of neural circuitry and understanding of brain function in health and disease, applications ranging from in vitro to work in behaving animals. Only recently (since 2010), the field has extended to cardiac applications with less than a dozen publications to date. In consideration of the early phase of work on cardiac optogenetics and the impact of the technique in understanding another excitable tissue, the brain, this review is largely a perspective of possibilities in the heart. It covers the basic principles of operation of light-sensitive ion channels and pumps, the available tools and ongoing efforts in optimizing them, overview of neuroscience use, as well as cardiac-specific questions of implementation and ideas for best use of this emerging technology in the heart. PMID:23457014

  1. Genetics of sudden cardiac death.

    PubMed

    Bezzina, Connie R; Lahrouchi, Najim; Priori, Silvia G

    2015-06-05

    Sudden cardiac death occurs in a broad spectrum of cardiac pathologies and is an important cause of mortality in the general population. Genetic studies conducted during the past 20 years have markedly illuminated the genetic basis of the inherited cardiac disorders associated with sudden cardiac death. Here, we review the genetic basis of sudden cardiac death with a focus on the current knowledge on the genetics of the primary electric disorders caused primarily by mutations in genes encoding ion channels, and the cardiomyopathies, which have been attributed to mutations in genes encoding a broader category of proteins, including those of the sarcomere, the cytoskeleton, and desmosomes. We discuss the challenges currently faced in unraveling genetic factors that predispose to sudden cardiac death in the setting of sequela of coronary artery disease and present the genome-wide association studies conducted in recent years on electrocardiographic parameters, highlighting their potential in uncovering new biological insights into cardiac electric function.

  2. Global ionospheric disturbances during super magnetic storms

    NASA Astrophysics Data System (ADS)

    Huang, C.; Foster, J.; Rideout, W.; Zhang, Y.; Paxton, L.

    2005-12-01

    Magnetic storms represent the largest disturbances in the magnetosphere and ionosphere. We will present the ionospheric observations by the Millstone Hill incoherent scatter radar, global GPS network, and TIMED GUVI instrument during two super storms. The sudden commencement (SSC) of the 15 July 2000 storm occurred at 19 UT, and the minimum Dst reached -301 nT. The dayside midlatitude ionospheric F region electron density showed a sudden decrease at Millstone Hill and Eglin in response to the SSC. The elevation scan measurements of the Millstone HIll radar show that the sudden decrease in the ionospheric electron density was related to an electron density trough which had an equatorward boundary at Eglin (magnetic latitude 41 degree) at 16 MLT. The formation of the trough may be related to equatorward incursion of the disturbance SAPS electric field. The dayside TEC decreased significantly at the equatorial and upper midlatitudes, and an enhanced TEC band occurred between the depleted regions. The SSC of the 29 October 2003 storm occurred at 07 UT, the storm was further enhanced at 18 UT, and the minimum Dst reached -363 nT. The Millstone Hill radar also detected a sudden decrease of the dayside F region electron density immediately after the storm enhancement. The simultaneous TIMED GUVI measurements show a significant decrease in the O/N2 ratio over the Atlantic sector from the auroral zone to anomaly latitudes, and large TEC depletions occurred coincidentally with the O/N2 decrease. In this second case, both the enhanced electric field and decrease of O/N2 ratio contributed to the depletion of the dayside midlatitude F-region electron density and TEC. The multiple measurements during the two storms reveal the distinct properties and mechanisms of the global ionospheric disturbances.

  3. Ionospheric data assimilation and forecasting during storms

    NASA Astrophysics Data System (ADS)

    Chartier, Alex T.; Matsuo, Tomoko; Anderson, Jeffrey L.; Collins, Nancy; Hoar, Timothy J.; Lu, Gang; Mitchell, Cathryn N.; Coster, Anthea J.; Paxton, Larry J.; Bust, Gary S.

    2016-01-01

    Ionospheric storms can have important effects on radio communications and navigation systems. Storm time ionospheric predictions have the potential to form part of effective mitigation strategies to these problems. Ionospheric storms are caused by strong forcing from the solar wind. Electron density enhancements are driven by penetration electric fields, as well as by thermosphere-ionosphere behavior including Traveling Atmospheric Disturbances and Traveling Ionospheric Disturbances and changes to the neutral composition. This study assesses the effect on 1 h predictions of specifying initial ionospheric and thermospheric conditions using total electron content (TEC) observations under a fixed set of solar and high-latitude drivers. Prediction performance is assessed against TEC observations, incoherent scatter radar, and in situ electron density observations. Corotated TEC data provide a benchmark of forecast accuracy. The primary case study is the storm of 10 September 2005, while the anomalous storm of 21 January 2005 provides a secondary comparison. The study uses an ensemble Kalman filter constructed with the Data Assimilation Research Testbed and the Thermosphere Ionosphere Electrodynamics General Circulation Model. Maps of preprocessed, verticalized GPS TEC are assimilated, while high-latitude specifications from the Assimilative Mapping of Ionospheric Electrodynamics and solar flux observations from the Solar Extreme Ultraviolet Experiment are used to drive the model. The filter adjusts ionospheric and thermospheric parameters, making use of time-evolving covariance estimates. The approach is effective in correcting model biases but does not capture all the behavior of the storms. In particular, a ridge-like enhancement over the continental USA is not predicted, indicating the importance of predicting storm time electric field behavior to the problem of ionospheric forecasting.

  4. Data analysis in cardiac arrhythmias.

    PubMed

    Rodrigo, Miguel; Pedrón-Torecilla, Jorge; Hernández, Ismael; Liberos, Alejandro; Climent, Andreu M; Guillem, María S

    2015-01-01

    Cardiac arrhythmias are an increasingly present in developed countries and represent a major health and economic burden. The occurrence of cardiac arrhythmias is closely linked to the electrical function of the heart. Consequently, the analysis of the electrical signal generated by the heart tissue, either recorded invasively or noninvasively, provides valuable information for the study of cardiac arrhythmias. In this chapter, novel cardiac signal analysis techniques that allow the study and diagnosis of cardiac arrhythmias are described, with emphasis on cardiac mapping which allows for spatiotemporal analysis of cardiac signals.Cardiac mapping can serve as a diagnostic tool by recording cardiac signals either in close contact to the heart tissue or noninvasively from the body surface, and allows the identification of cardiac sites responsible of the development or maintenance of arrhythmias. Cardiac mapping can also be used for research in cardiac arrhythmias in order to understand their mechanisms. For this purpose, both synthetic signals generated by computer simulations and animal experimental models allow for more controlled physiological conditions and complete access to the organ.

  5. Electricity

    SciTech Connect

    Sims, B.

    1983-01-01

    Historical aspects of electricity are reviewed with individual articles on hydroelectric dams, coal-burning power plants, nuclear power plants, electricity distribution, and the energy future. A glossary is included. (PSB)

  6. Effects of a geomagnetic storm on thermospheric circulation. Master's thesis

    SciTech Connect

    Brinkman, D.G.

    1987-01-01

    The motions of the thermosphere and its interactions with the ionosphere during a geomagnetic storm are of current interest to space scientists. A two-dimensional model was used to simulate the thermospheric response to the impulsive high-latitude heating associated with a geomagnetic storm. The storm-induced motions can be characterized by an initial period of transient waves followed by the development of a mean circulation. These motions generate an electrical-current system that is on the same order of magnitude as, and in the opposite sense to the normal s/sub q/ current system. Model-simulated winds and electrical currents were then compared to observations.

  7. Control of a rotary pulsatile cardiac assist pump driven by an electric motor without a pressure sensor to avoid collapse of the pump inlet.

    PubMed

    Trinkl, J; Havlik, P; Mesana, T; Mitsui, N; Morita, S; Demunck, J L; Tourres, J L; Monties, J R

    1993-01-01

    Our ventricular assist device uses a valveless volumetric pump operating on the Maillard-Wankel rotary principle. It is driven by an electric motor and provides a semi pulsatile flow. At each cycle, blood is actively aspirated into the device, and overpumping results in collapse at the pump inlet. To prevent overpumping, it is necessary to ensure that pump intake does not exceed venous return. Poor long-term reliability rules out the use of current implantable pressure sensors for this purpose. To resolve this problem, we have developed a method of control based on monitoring of the intensity of electric current consumed by the motor. The method consists of real time monitoring of current intensity at the beginning of each pump cycle. A sudden change in intensity indicates underfilling, and motor speed is reduced to prevent collapse. The current consumed by the motor also depends on the afterload, but the form of the signal remains the same when afterload changes. After demonstrating the feasibility of this technique in a simulator, we are now testing it in animals. We were able to detect and prevent collapse due to overpumping by the cardiac assist device. This system also enables us to know the maximum possible assistance and to thus adapt assistance to the user.

  8. Dust storms: recent developments.

    PubMed

    Goudie, Andrew S

    2009-01-01

    Dust storms have a number of impacts upon the environment including radiative forcing, and biogeochemical cycling. They transport material over many thousands of kilometres. They also have a range of impacts on humans, not least on human health. In recent years the identification of source areas for dust storms has been an important area or research, with the Sahara (especially Bodélé) and western China being recognised as the strongest sources globally. Another major development has been the recognition of the degree to which dust storm activity has varied at a range of time scales, millennial, century, decadal, annual and seasonal.

  9. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

    Geomagnetic storms are large and sometimes rapid fluctuations in the Earth's magnetic field that are related to disturbances on the Sun's surface. Although it is not widely recognized, these transient magnetic disturbances can be a significant hazard to people and property. Many of us know that the intensity of the auroral lights increases during magnetic storms, but few people realize that these storms can also cause massive power outages, interrupt radio communications and satellite operations, increase corrosion in oil and gas pipelines, and lead to spuriously high rejection rates in the manufacture of sensitive electronic equipment. 

  10. 2001 Leonid Meteoroid Storm

    DTIC Science & Technology

    2007-11-02

    and discuss their possible consequences and mitigation strategies. 15. SUBJECT TERMS Meteors , Leonids, Meteoroids, Spacecraft, Meteor showers , Impact...release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT We present the latest predictions about the November 2001 Leonid Meteor storms

  11. Powerful Midwest Storm System

    NASA Video Gallery

    This animation of imagery from NOAA’s GOES-13 satellite shows themovement of storm systems in the south central United States on May 20,2013. Warm, moist gulf air flowing across Texas, Oklahoma...

  12. Tropical Storm Faxai

    NASA Video Gallery

    NASA/JAXA's TRMM Satellite provided data of developing Tropical Storm Faxai to make this 3-D image that showed some towering thunderstorms in the area were reaching altitudes of up to 15.5km/~9.6 m...

  13. Tropical Storm Don

    NASA Video Gallery

    GOES-13 data was compiled into an animation by the NASA GOES Project at NASA Goddard that shows the development of Tropical Storm Don in the southern Gulf of Mexico, west of Cuba. The animation run...

  14. Tropical Storm Dolly Develops

    NASA Video Gallery

    This animation from NOAA's GOES-East satellite from Aug. 31-Sept. 2 shows the movement of a low pressure area from the western Caribbean Sea over the Yucatan Peninsula as it becomes Tropical Storm ...

  15. Inter-individual variability and modeling of electrical activity: a possible new approach to explore cardiac safety?

    PubMed Central

    Le Guennec, Jean-Yves; Thireau, Jérôme; Ouillé, Aude; Roussel, Julien; Roy, Jérôme; Richard, Serge; Richard, Sylvain; Martel, Eric; Champéroux, Pascal

    2016-01-01

    Safety pharmacology aims to predict rare side effects of new drugs. We explored whether rare pro-arrhythmic effects could be linked to the variability of the effects of these drugs on ion currents and whether taking into consideration this variability in computational models could help to better detect and predict cardiac side effects. For this purpose, we evaluated how intra- and inter-individual variability influences the effect of hERG inhibition on both the action potential duration and the occurrence of arrhythmias. Using two computer simulation models of human action potentials (endocardial and Purkinje cells), we analyzed the contribution of two biological parameters on the pro-arrhythmic effects of several hERG channel blockers: (i) spermine concentration, which varies with metabolic status, and (ii) L-type calcium conductance, which varies due to single nucleotide polymorphisms or mutations. By varying these parameters, we were able to induce arrhythmias in 1 out of 16 simulations although conventional modeling methods to detect pro-arrhythmic molecules failed. On the basis of our results, taking into consideration only 2 parameters subjected to intra- and inter-individual variability, we propose that in silico computer modeling may help to better define the risks of new drug candidates at early stages of pre-clinical development. PMID:27901061

  16. Lightning parameterization in a storm electrification model

    NASA Technical Reports Server (NTRS)

    Helsdon, John H., Jr.; Farley, Richard D.; Wu, Gang

    1988-01-01

    The parameterization of an intracloud lightning discharge has been implemented in our Storm Electrification Model. The initiation, propagation direction, termination and charge redistribution of the discharge are approximated assuming overall charge neutrality. Various simulations involving differing amounts of charge transferred have been done. The effects of the lightning-produced ions on the hydrometeor charges, electric field components and electrical energy depend strongly on the charge transferred. A comparison between the measured electric field change of an actual intracloud flash and the field change due to the simulated discharge show favorable agreement.

  17. Cardiac catheterization - discharge

    MedlinePlus

    Catheterization - cardiac - discharge; Heart catheterization - discharge: Catheterization - cardiac; Heart catheterization; Angina - cardiac catheterization discharge; CAD - cardiac catheterization discharge; Coronary artery disease - cardiac catheterization ...

  18. The relationship of storm severity to directionally resolved radio emissions

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.

    1986-01-01

    The objective was to provide continuous observation of atmospheric electrical activity occurring in association with tropical storms in the Gulf of Mexico. The observations were to include the location of all detected intracloud and cloud-to-ground lightning activity occurring in the storm. To provide synoptic scale coverage, a phase linear interferometer high frequency direction finder (HFDF) system was constructed and developed at Marshall Space Flight Center (MSFC). This was used in concert with the existing HFDF interferometer at the southwest research institute to provide lightning location data through triangulation. Atmospheric electrical events were synchronized through the use of satellite receivers at each site. The intent of the data analysis was to correlate the location of electrical centers of activity with radar and satellite imagry to identify areas of intense convection within the tropical storm system. Analysis of the hurricane Alicia data indicate a center of atmospheric electrical activity associated with the vortex of the storm. The center appears to rotate from the Northern side of the vortex to the Southern side during the period of observation. An analysis of the atmospheric electrical burst rates associated with hurrican Alicia indicates that the electrical activity appears to maximize at the time of greatest storm intensity, i.e., maximum winds and lowest central pressure.

  19. Coastal storm monitoring in Virginia

    USGS Publications Warehouse

    Wicklein, Shaun M.; Bennett, Mark

    2014-01-01

    Coastal communities in Virginia are prone to flooding, particularly during hurricanes, nor’easters, and other coastal low-pressure systems. These weather systems affect public safety, personal and public property, and valuable infrastructure, such as transportation, water and sewer, and electric-supply networks. Local emergency managers, utility operators, and the public are tasked with making difficult decisions regarding evacuations, road closures, and post-storm recovery efforts as a result of coastal flooding. In coastal Virginia these decisions often are made on the basis of anecdotal knowledge from past events or predictions based on data from monitoring sites located far away from the affected area that may not reflect local conditions. Preventing flood hazards, such as hurricane-induced storm surge, from becoming human disasters requires an understanding of the relative risks that flooding poses to specific communities. The risk to life and property can be very high if decisions about evacuations and road closures are made too late or not at all.

  20. Great magnetic storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Lee, Yen T.; Gonzalez, Walter D.; Tang, Frances

    1992-01-01

    The five largest magnetic storms that occurred between 1971 to 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that: (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective.

  1. Storms and Moons

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons Long Range Reconnaissance Imager (LORRI) took this 2-millisecond exposure of Jupiter at 04:41:04 UTC on January 24, 2007. The spacecraft was 57 million kilometers (35.3 million miles) from Jupiter, closing in on the giant planet at 41,500 miles (66,790 kilometers) per hour. At right are the moons Io (bottom) and Ganymede; Ganymede's shadow creeps toward the top of Jupiter's northern hemisphere.

    Two of Jupiter's largest storms are visible; the Great Red Spot on the western (left) limb of the planet, trailing the Little Red Spot on the eastern limb, at slightly lower latitude. The Great Red Spot is a 300-year old storm more than twice the size of Earth. The Little Red Spot, which formed over the past decade from the merging of three smaller storms, is about half the size of its older and 'greater' counterpart.

  2. Storm Warning Service

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A Huntsville meteorologist of Baron Services, Inc. has formed a commercial weather advisory service. Weather information is based on data from Marshall Space Flight Center (MSFC) collected from antennas in Alabama and Tennessee. Bob Baron refines and enhances MSFC's real time display software. Computer data is changed to audio data for radio transmission, received by clients through an antenna and decoded by computer for display. Using his service, clients can monitor the approach of significant storms and schedule operations accordingly. Utilities and emergency management officials are able to plot a storm's path. A recent agreement with two other companies will promote continued development and marketing.

  3. Superposed Epoch Analysis of Current Systems During Intense Magnetic Storms

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Katus, R. M.

    2013-05-01

    A statistical approach to investigating the intensity and timing of storm-time current systems is conducted and presented. The Hot Electron and Ion Drift Integrator (HEIDI) model was used to simulate all of the intense storms (Dstmin < -100 nT) from solar cycle 23 (1996-2005). Five different HEIDI input combinations were used to create a large collection of numerical results, varying the plasma outer boundary condition and electric field description in the model. The simulation results are then combined with a normalized superposed epoch analysis, where each phase of each storm is prorated to the average duration of that phase and then all of the storms are averaged together. The azimuthal currents in the HEIDI simulation domain are classified as westward and eastward symmetric ring current, partial ring current, banana current, and tail current. The average behavior of these current systems with respect to the HEIDI plasma and electric field boundary conditions are then presented and discussed. It is found that the Volland-Stern electric field produces an earlier increase in the inner magnetospheric current systems because of the usage of the 3-h Kp index. A self-consistent electric field develops the current systems a few hours later, but produces much stronger asymmetric current systems (partial, banana, and tail currents), especially in the main phase of the storm. Applying a nonuniform local time distribution for the plasma outer boundary condition slightly increases the magnitudes of the current systems, but this effect is smaller than the electric field influence.

  4. A Case of Thyroid Storm Associated with Cardiomyopathy and Poststreptococcal Glomerulonephritis.

    PubMed

    Underland, Lisa J; Villeda, Gerson A Vallencia; Pal, Abhijeet; Lam, Leslie

    2016-01-01

    Thyroid storm has a high mortality rate and is often associated with a precipitating factor such as intercurrent illness or infection. It is rare in pediatric patients. Cardiac disease in hyperthyroidism mostly manifests itself as tachycardia but more serious cardiac findings have also been described. A 5-year-old male with recent strep throat infection presented with dilated cardiomyopathy, hematuria, and symptoms and lab findings consistent with severe hyperthyroidism. He was diagnosed with thyroid storm secondary to concurrent Graves' disease and poststreptococcal glomerulonephritis (PSGN). After starting the treatment with methimazole and a beta-blocker, his cardiac disease gradually improved and the PSGN resolved over time. There are no specific pediatric criteria for thyroid storm. Adult criteria can be difficult to apply to pediatric cases. Criteria for diagnosis of thyroid storm are less clear for pediatric patients. Dilated cardiomyopathy is a rare cardiac manifestation of hyperthyroidism. PSGN is due to glomerular immune complexes and can complicate group A strep infection. Providers should be aware of cardiac disease as a complication of hyperthyroidism. PSGN should not mechanistically be related to hyperthyroidism but can precipitate the signs of thyroid storm such as hypertension. This association has not been previously reported in the literature.

  5. Tropical Storm Lee to Newfoundland

    NASA Video Gallery

    This video shows Tropical Storm Lee as it made landfall in Louisiana and Mississippi on September 4, 2011. This storm produced flooding and tornadoes to the southern states all the way to flooding ...

  6. California's Perfect Storm

    ERIC Educational Resources Information Center

    Bacon, David

    2010-01-01

    The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

  7. Tropical Storm Katrina

    Atmospheric Science Data Center

    2014-05-15

    ... Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are ... nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper ...

  8. STORM INLET FILTRATION DEVICE

    EPA Science Inventory

    Five field tests were conducted to evaluate the effectiveness of the Storm and Groundwater Enhancement Systems (SAGES) device for removing contaminants from stormwater. The SAGES device is a three-stage filtering system that could be used as a best management practices (BMP) retr...

  9. Recovery from major storms

    SciTech Connect

    Holeman, J.S.

    1980-01-01

    Public Service Company of Oklahoma's transmission and distribution system is in tornado alley, and it seems the number of tornados hitting some part of the system is increasing each year. In the past 30 years, Tulsa his been hit 7 times, and experienced 3 very wide and destructive tornado storm systems between 1971 and 1975.

  10. Estimation of Observatory Geoelectric Fields Induced during Great Magnetic Storms

    NASA Astrophysics Data System (ADS)

    Love, J. J.; Swidinsky, A.

    2014-12-01

    In support of a project for monitoring hazards for electric power grids, we present a new method for estimating electric fields that are induced in the Earth's interior at a particular site during magnetic storms. For this, we adopt a model of the electrical conductivity of the lithosphere that is simple but sufficient to model most variation in the induced geoelectric field: two horizontal layers, each with uniform electrical conductivity properties that can be parameterized by a galvanic distortion tensor. After Laplace transformation of the induction equations into the complex frequency domain, we obtain an electromagnetic impedance function. Upon inverse transformation back to the time domain, convolution of the impedance tensor with a geomagnetic time series yields an estimated geoelectric time series. We optimize the model conductivity parameters using 1-sec resolution magnetic and electric field data collected at the Kakioka magnetic observatory during the October 2003 Halloween storm. We validate the algorithm against Kakioka magnetic and electric field data for the July 2000 Bastille-Day storm. Finally, we infer 1-sec geoelectric fields that were realized (but not directly measured) in Japan during the 1989 Quebec storm. Results highlight the need for improved ground-level monitoring of geomagnetic and geoelectric fields. They also reveal the need for accommodating the galvanic distortion of three-dimensional conductivity when predicting geoelectric fields in the lithosphere and geomagnetically induced currents in electric power grids.

  11. Cardiac Electrophysiology: Normal and Ischemic Ionic Currents and the ECG

    ERIC Educational Resources Information Center

    Klabunde, Richard E.

    2017-01-01

    Basic cardiac electrophysiology is foundational to understanding normal cardiac function in terms of rate and rhythm and initiation of cardiac muscle contraction. The primary clinical tool for assessing cardiac electrical events is the electrocardiogram (ECG), which provides global and regional information on rate, rhythm, and electrical…

  12. Endogenous endothelin 1 mediates angiotensin II-induced hypertrophy in electrically paced cardiac myocytes through EGFR transactivation, reactive oxygen species and NHE-1.

    PubMed

    Correa, María V; Nolly, Mariela B; Caldiz, Claudia I; de Cingolani, Gladys E Chiappe; Cingolani, Horacio E; Ennis, Irene L

    2014-09-01

    Emerging evidence supports a key role for endothelin-1 (ET-1) and the transactivation of the epidermal growth factor receptor (EGFR) in angiotensin II (Ang II) action. We aim to determine the potential role played by endogenous ET-1, EGFR transactivation and redox-dependent sodium hydrogen exchanger-1 (NHE-1) activation in the hypertrophic response to Ang II of cardiac myocytes. Electrically paced adult cat cardiomyocytes were placed in culture and stimulated with 1 nmol l(-1) Ang II or 5 nmol l(-1) ET-1. Ang II increased ~45 % cell surface area (CSA) and ~37 % [(3)H]-phenylalanine incorporation, effects that were blocked not only by losartan (Los) but also by BQ123 (AT1 and ETA receptor antagonists, respectively). Moreover, Ang II significantly increased ET-1 messenger RNA (mRNA) expression. ET-1 similarly increased myocyte CSA and protein synthesis, actions prevented by the reactive oxygen species scavenger MPG or the NHE-1 inhibitor cariporide (carip). ET-1 increased the phosphorylation of the redox-sensitive ERK1/2-p90(RSK) kinases, main activators of the NHE-1. This effect was prevented by MPG and the antagonist of EGFR, AG1478. Ang II, ET-1 and EGF increased myocardial superoxide production (187 ± 9 %, 149 ± 8 % and 163.7 ± 6 % of control, respectively) and AG1478 inhibited these effects. Interestingly, Los inhibited only Ang II whilst BQ123 cancelled both Ang II and ET-1 actions, supporting the sequential and unidirectional activation of AT1, ETA and EGFR. Based on the present evidence, we propose that endogenous ET-1 mediates the hypertrophic response to Ang II by a mechanism that involves EGFR transactivation and redox-dependent activation of the ERK1/2-p90(RSK) and NHE-1 in adult cardiomyocytes.

  13. Mechanisms of cardiac arrhythmias

    PubMed Central

    Tse, Gary

    2015-01-01

    Blood circulation is the result of the beating of the heart, which provides the mechanical force to pump oxygenated blood to, and deoxygenated blood away from, the peripheral tissues. This depends critically on the preceding electrical activation. Disruptions in the orderly pattern of this propagating cardiac excitation wave can lead to arrhythmias. Understanding of the mechanisms underlying their generation and maintenance requires knowledge of the ionic contributions to the cardiac action potential, which is discussed in the first part of this review. A brief outline of the different classification systems for arrhythmogenesis is then provided, followed by a detailed discussion for each mechanism in turn, highlighting recent advances in this area. PMID:27092186

  14. Historic and Future Ice Storms

    NASA Astrophysics Data System (ADS)

    Klima, K.; Morgan, M. G.

    2014-12-01

    Ice storm losses from business interruption as well as transportation and health damages can range into billions of dollars. For instance, the December 2008 New England and Upstate New York ice storm caused four deaths and monetary damages between 2.5 and 3.7 billion, and the 2008 Chinese winter storms resulted in over 130 deaths and over 20 billion in damages. Informal discussions with ice storm experts indicate that due to competing temperature and precipitation effects as well as local topographic effects, it is unclear how exactly climate change will affect ice storms. Here we ask how incident frequencies might change in a future climate at four weather stations prone to ice storms. Using historical atmospheric soundings, we conduct a thought experiment where we perturb the temperatures as might be expected in a future climate. We then discuss changes in monthly frequency of ice storms.

  15. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Lefevre, L.; Dumbović, M.; Crosby, N.; Malandraki, O.; Patsou, I.; Clette, F.; Veronig, A.; Vršnak, B.; Leer, K.; Moretto, T.

    2016-05-01

    We present the first large statistical study of extreme geomagnetic storms based on historical data from the time period 1868 - 2010. This article is the first of two companion papers. Here we describe how the storms were selected and focus on their near-Earth characteristics. The second article presents our investigation of the corresponding solar events and their characteristics. The storms were selected based on their intensity in the aa index, which constitutes the longest existing continuous series of geomagnetic activity. They are analyzed statistically in the context of more well-known geomagnetic indices, such as the Kp and Dcx/Dst index. This reveals that neither Kp nor Dcx/Dst provide a comprehensive geomagnetic measure of the extreme storms. We rank the storms by including long series of single magnetic observatory data. The top storms on the rank list are the New York Railroad storm occurring in May 1921 and the Quebec storm from March 1989. We identify key characteristics of the storms by combining several different available data sources, lists of storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks, solar wind in-situ measurements, neutron monitor data, and associated identifications of Forbush decreases as well as satellite measurements of energetic proton fluxes in the near-Earth space environment. From this we find, among other results, that the extreme storms are very strongly correlated with the occurrence of interplanetary shocks (91 - 100 %), Forbush decreases (100 %), and energetic solar proton events (70 %). A quantitative comparison of these associations relative to less intense storms is also presented. Most notably, we find that most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar wind disturbances and that they frequently occur when the geomagnetic activity is already elevated. We also investigate the semiannual variation in storm occurrence

  16. Dust Storm, Aral Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Aral Sea has shrunk to less than half its size since 1985. The Aral Sea receives little water (sometimes no water) from the two major rivers that empty into it-the Syr Darya and Amu Darya. Instead, the river water is diverted to support irrigation for the region's extensive cotton fields. Recently, water scarcity has increased due to a prolonged drought in Central Asia. As the Aral Sea recedes, its former sea bed is exposed. The Aral's sea bed is composed of fine sediments-including fertilizers and other agricultural chemicals-that are easily picked up by the region's strong winds, creating thick dust storms. The International Space Station crew observed and recorded a large dust storm blowing eastward from the Aral Sea in late June 2001. This image illustrates the strong coupling between human activities (water diversions and irrigation), and rapidly changing land, sea and atmospheric processes-the winds blow across the

  17. Ice Storm Supercomputer

    SciTech Connect

    2009-01-01

    "A new Idaho National Laboratory supercomputer is helping scientists create more realistic simulations of nuclear fuel. Dubbed 'Ice Storm,' this 2048-processor machine allows researchers to model and predict the complex physics behind nuclear reactor behavior. And with a new visualization lab, the team can see the results of its simulations on the big screen." For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  18. Ice Storm Supercomputer

    ScienceCinema

    None

    2016-07-12

    "A new Idaho National Laboratory supercomputer is helping scientists create more realistic simulations of nuclear fuel. Dubbed 'Ice Storm,' this 2048-processor machine allows researchers to model and predict the complex physics behind nuclear reactor behavior. And with a new visualization lab, the team can see the results of its simulations on the big screen." For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  19. How Ionospheric Ions Populate the Magnetosphere during a Magnetic Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, T. E.; Kistler, L. M.; Slinker, S. P.; Fedder, J. A.; Delcourt, D. C.

    2008-01-01

    Ionospheric oxygen ions have been observed throughout the magnetosphere, from the plasma sheet to the ring current region. I t has been found that the O+ /H+ density ratio in the magnetosphere increases with geomagnetic activity and varies with storm phases. During the magnetic storm in late September to earIy October 2002, Cluster was orbiting in the plasma sheet and ring current regions. At prestorm time, Cluster observed high H+ density and low O+ density in the plasma sheet and lobes. During the storm main phase, 0+ density has increased by 10 times over the pre-storm level. Strong field-aligned beams of O+ were observed in the lobes. O+ fluxes were significantly reduced in the central plasma sheet during the storm recovery. However, 0+ was still evident on the boundaries of the plasma sheet and in the lobes. In order to interpret the Cluster observations and to understand how O+ ions populate the magnetosphere during a magnetic storm, we model the storm in early October 2002 using our global ion kinetic simulation (GIK). We use the LFN global simulation model to produce electric and magnetic fields in the outer magnetosphere, the Strangeway outflow scaling with Delcourt ion trajectories to include ionospheric outflows, and the Fok inner magnetospheric model for the plasmaspheric and ring current response to all particle populations. We find that the observed composition features are qualitatively reproduced by the simulations, with some quantitative differences that point to future improvements in the models.

  20. Cardiac Sarcoidosis.

    PubMed

    Birnie, David; Ha, Andrew C T; Gula, Lorne J; Chakrabarti, Santabhanu; Beanlands, Rob S B; Nery, Pablo

    2015-12-01

    Studies suggest clinically manifest cardiac involvement occurs in 5% of patients with pulmonary/systemic sarcoidosis. The principal manifestations of cardiac sarcoidosis (CS) are conduction abnormalities, ventricular arrhythmias, and heart failure. Data indicate that an 20% to 25% of patients with pulmonary/systemic sarcoidosis have asymptomatic (clinically silent) cardiac involvement. An international guideline for the diagnosis and management of CS recommends that patients be screened for cardiac involvement. Most studies suggest a benign prognosis for patients with clinically silent CS. Immunosuppression therapy is advocated for clinically manifest CS. Device therapy, with implantable cardioverter defibrillators, is recommended for some patients.

  1. Defining Coastal Storm and Quantifying Storms Applying Coastal Storm Impulse Parameter

    NASA Astrophysics Data System (ADS)

    Mahmoudpour, Nader

    2014-05-01

    What defines a storm condition and what would initiate a "storm" has not been uniquely defined among scientists and engineers. Parameters that have been used to define a storm condition can be mentioned as wind speed, beach erosion and storm hydrodynamics parameters such as wave height and water levels. Some of the parameters are storm consequential such as beach erosion and some are not directly related to the storm hydrodynamics such as wind speed. For the purpose of the presentation, the different storm conditions based on wave height, water levels, wind speed and beach erosion will be discussed and assessed. However, it sounds more scientifically to have the storm definition based on the hydrodynamic parameters such as wave height, water level and storm duration. Once the storm condition is defined and storm has initiated, the severity of the storm would be a question to forecast and evaluate the hazard and analyze the risk in order to determine the appropriate responses. The correlation of storm damages to the meteorological and hydrodynamics parameters can be defined as a storm scale, storm index or storm parameter and it is needed to simplify the complexity of variation involved developing the scale for risk analysis and response management. A newly introduced Coastal Storm Impulse (COSI) parameter quantifies storms into one number for a specific location and storm event. The COSI parameter is based on the conservation of linear, horizontal momentum to combine storm surge, wave dynamics, and currents over the storm duration. The COSI parameter applies the principle of conservation of momentum to physically combine the hydrodynamic variables per unit width of shoreline. This total momentum is then integrated over the duration of the storm to determine the storm's impulse to the coast. The COSI parameter employs the mean, time-averaged nonlinear (Fourier) wave momentum flux, over the wave period added to the horizontal storm surge momentum above the Mean High

  2. Weather radar research at the USA's storm laboratory

    NASA Technical Reports Server (NTRS)

    Doviak, R. J.

    1982-01-01

    Radar research that is directed toward improving storm forecasts and hazard warnings and studying lightning is discussed. The two moderately sensitive Doppler weather radars in central Oklahoma, with their wide dynamic range, have demonstrated the feasibility of mapping wind fields in all weather conditions from the clear skies of quiescent air and disturbed prestorm air near the earth's surface to the optically opaque interior of severe and sometimes tornadic thunderstorms. Observations and analyses of Doppler weather radar data demonstrate that improved warning of severe storm phenomena and improved short-term forecast of storms may be available when Doppler techniques are well integrated into the national network of weather radars. When used in combination with other sensors, it provides an opportunity to learn more about the complex interrelations between the wind, water, and electricity in storms.

  3. Statistical analysis of geomagnetic storm driver and intensity

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.

    2013-05-01

    Geomagnetic storms are investigated statistically with respect to the solar wind driver and the intensity of the events. The Hot Electron and Ion Drift Integrator (HEIDI) model was used to simulate all of the intense storms (minimum Dst < - 100 nT) from solar cycle 23 (1996-2005). Four different configurations of HEIDI were used to investigate the outer boundary condition and electric field description. The storms are then classified as being a coronal mass ejection (CME) or corotating interaction region (CIR) driven event and binned based on the magnitude of the minimum Dst. The simulation results as well as solar wind and geomagnetic data sets are then analyzed along a normalized epoch timeline. The average behavior of each storm type and the corresponding HEIDI configurations are then presented and discussed. It is found that while the self-consistent electric field better reproduces stronger CME driven storms, the Volland-Stern electric field does well reproducing the results for CIR driven events.

  4. Storm-Substorm Relations Workshop

    NASA Astrophysics Data System (ADS)

    Kan, Joe

    2006-06-01

    Magnetic storms in the magnetosphere can cause damage to communication satellites and large-scale power outages. The concept that a magnetic storm is a compilation of a series of substorms was proposed by Akasofu [1968]. However, Kamide [1992] showed that substorms are not a necessary condition for the occurrence of a magnetic storm. This controversy initiated a new era of research on the storm-substorm relation, which was the subject of a recent workshop in Banff, Alberta, Canada. The main topics discussed during the meeting included a brief overview of what a substorm is, how quasiperiodic substorm events and steady magnetospheric convection (SMC) events without substorms contribute to storms, and how plasma flows enhanced by magnetic reconnection in the plasma sheet contribute to substorms and storms.

  5. THE CHEMOTHERAPY OF CARDIAC ARREST.

    PubMed

    MINUCK, M

    1965-01-02

    Direct-air ventilation, external cardiac compression, and external defibrillation are established techniques for patients who unexpectedly develop cardiac arrest. The proper use of drugs can increase the incidence of successful resuscitation. Intracardiac adrenaline (epinephrine) acts as a powerful stimulant during cardiac standstill and, in addition, converts fine ventricular fibrillation to a coarser type, more responsive to electrical defibrillation. Routine use of intravenous sodium bicarbonate is recommended to combat the severe metabolic acidosis accompanying cardiac arrest. Lidocaine is particularly useful when ventricular fibrillation or ventricular tachycardia tends to recur. Analeptics are contraindicated, since they invariably increase oxygen requirements of already hypoxic cerebral tissues. The following acrostic is a useful mnemonic for recalling the details of the management of cardiac arrest in their proper order: A (Airway), B (Breathing), C (Circulation), D (Diagnosis of underlying cause), E (Epinephrine), F (Fibrillation), G (Glucose intravenously), pH (Sodium bicarbonate), I (Intensive care).

  6. Desert Shield/Storm Logistics

    DTIC Science & Technology

    1993-04-15

    Wc This document may not be retee for open publiarion until it has bm deaed by the Vproprnite military service or gmeanen agency. DESERT SHIELD /STORM...capture what had occurred during Operations DESERT SHIELD and STORM, the commanders of the Division Support Command of the 24th Infantry Division...Mechanized) held a ful. day of discussion centering on what occurted during Operation DESERT STORM and its preceding operation, DESERT SHIELD . The entire

  7. Tropical Storm Erin

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Location: The Atlantic Ocean 210 miles south of Galveston, Texas Categorization: Tropical Storm Sustained Winds: 40 mph (60 km/hr)

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Infrared ImageMicrowave Image

    Infrared Images Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

    Microwave Images In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

    Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue

  8. Empirical STORM-E Model. [I. Theoretical and Observational Basis

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin G.; Russell, James M., III

    2013-01-01

    Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3 lm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 lm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 lm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3 lm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented

  9. Communicating Storm Surge Forecast Uncertainty

    NASA Astrophysics Data System (ADS)

    Troutman, J. A.; Rhome, J.

    2015-12-01

    When it comes to tropical cyclones, storm surge is often the greatest threat to life and property along the coastal United States. The coastal population density has dramatically increased over the past 20 years, putting more people at risk. Informing emergency managers, decision-makers and the public about the potential for wind driven storm surge, however, has been extremely difficult. Recently, the Storm Surge Unit at the National Hurricane Center in Miami, Florida has developed a prototype experimental storm surge watch/warning graphic to help communicate this threat more effectively by identifying areas most at risk for life-threatening storm surge. This prototype is the initial step in the transition toward a NWS storm surge watch/warning system and highlights the inundation levels that have a 10% chance of being exceeded. The guidance for this product is the Probabilistic Hurricane Storm Surge (P-Surge) model, which predicts the probability of various storm surge heights by statistically evaluating numerous SLOSH model simulations. Questions remain, however, if exceedance values in addition to the 10% may be of equal importance to forecasters. P-Surge data from 2014 Hurricane Arthur is used to ascertain the practicality of incorporating other exceedance data into storm surge forecasts. Extracting forecast uncertainty information through analyzing P-surge exceedances overlaid with track and wind intensity forecasts proves to be beneficial for forecasters and decision support.

  10. Toward storm-time ionosphere forecast using GNSS observations

    NASA Astrophysics Data System (ADS)

    Lin, Charles; Chen, Chia-Hung; Liu, Tiger J. Y.; Chen, Wei-Han

    2016-04-01

    Previous theoretical simulations of the mid- and low-latitude ionospheric responses to space weather events have indicated general features of electron density disturbances. The magnetic storm produced penetration electric field and neutral wind disturbances lead to formation of various storm-time ionospheric electron density structures, such as super plasma fountain, equatorial electron density trough and F3 layer, as well as long-lasting global ionosphere suppression. We attempt to model these storm-related ionospheric electron density structures using the global assimilative ionospheric model that assimilates electron densities taken from FORMOSAT-3/COSMIC and TEC from ground-based GNSS receivers. Using the ensemble Kalman filter with consideration of ion densities, electric potential, thermospheric neutral wind and compositions as update variables, we study the performance and forecast capability of the assimilative model. The assimilative model could be utilized for ionosphere forecast in near future.

  11. Molecular Aspects of Exercise-induced Cardiac Remodeling.

    PubMed

    Bernardo, Bianca C; McMullen, Julie R

    2016-11-01

    Exercise-induced cardiac remodeling is typically an adaptive response associated with cardiac myocyte hypertrophy and renewal, increased cardiac myocyte contractility, sarcomeric remodeling, cell survival, metabolic and mitochondrial adaptations, electrical remodeling, and angiogenesis. Initiating stimuli/triggers of cardiac remodeling include increased hemodynamic load, increased sympathetic activity, and the release of hormones and growth factors. Prolonged and strenuous exercise may lead to maladaptive exercise-induced cardiac remodeling including cardiac dysfunction and arrhythmia. In addition, this article describes novel therapeutic approaches for the treatment of heart failure that target mechanisms responsible for adaptive exercise-induced cardiac remodeling, which are being developed and tested in preclinical models.

  12. Cardiac Cephalgia

    PubMed Central

    Wassef, Nancy; Ali, Ali Turab; Katsanevaki, Alexia-Zacharoula; Nishtar, Salman

    2014-01-01

    Although most of the patients presenting with ischemic heart disease have chest pains, there are other rare presenting symptoms like cardiac cephalgia. In this report, we present a case of acute coronary syndrome with an only presentation of exertional headache. It was postulated as acute presentation of coronary artery disease, due to previous history of similar presentation associated with some chest pains with previous left coronary artery stenting. We present an unusual case with cardiac cephalgia in a young patient under the age of 50 which was not reported at that age before. There are four suggested mechanisms for this cardiac presentation. PMID:28352454

  13. Ionospheric redistribution during geomagnetic storms.

    PubMed

    Immel, T J; Mannucci, A J

    2013-12-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

  14. Thyroid storm: an updated review.

    PubMed

    Chiha, Maguy; Samarasinghe, Shanika; Kabaker, Adam S

    2015-03-01

    Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition.

  15. Clouds and Dust Storms

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

    Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with

  16. Nuclear cardiac

    SciTech Connect

    Slutsky, R.; Ashburn, W.L.

    1982-01-01

    The relationship between nuclear medicine and cardiology has continued to produce a surfeit of interesting, illuminating, and important reports involving the analysis of cardiac function, perfusion, and metabolism. To simplify the presentation, this review is broken down into three major subheadings: analysis of myocardial perfusion; imaging of the recent myocardial infarction; and the evaluation of myocardial function. There appears to be an increasingly important relationship between cardiology, particularly cardiac physiology, and nuclear imaging techniques. (KRM)

  17. Cardiac cameras.

    PubMed

    Travin, Mark I

    2011-05-01

    Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes.

  18. Cardiac catheterization laboratory imaging quality assurance program.

    PubMed

    Wondrow, M A; Laskey, W K; Hildner, F J; Cusma, J; Holmes, D R

    2001-01-01

    With the recent approval of the National Electrical Manufacturers Association (NEMA) standard for "Characteristics of and Test Procedures for a Phantom to Benchmark Cardiac Fluoroscopic and Photographic Performance," comprehensive cardiac image assurance control programs are now possible. This standard was developed by a joint NEMA/Society for Cardiac Angiography and Interventions (SCA&I) working group of imaging manufacturers and cardiology society professionals over the past 4 years. This article details a cardiac catheterization laboratory image quality assurance and control program that includes the new standard along with current regulatory requirements for cardiac imaging. Because of the recent proliferation of digital imaging equipment, quality assurance for cardiac imaging fluoroscopy and digital imaging are critical. Included are the previous works recommended by the American College of Cardiology (ACC) and American Heart Association (AHA), Society for Cardiac Angiographers and Interventions (SCA&I), and authors of previous image quality subjects.

  19. Dust storm in Chad

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Chad (lower left) and the surrounding wetlands are under increasing pressure from desertification. The encroachment of the Sahara occurs with creeping sand dunes and major dust storms, such as the one pictured in this MODIS image from October 28, 2001. The amount of open water (lighter green patch within the darker one) has declined markedly over the last decades and the invasion of dunes is creating a rippled effect through the wetlands that is all too clear in the high-resolution images. Growing population and increasing demands on the lake give it an uncertain future. The loss of such an important natural resource will have profound effects on the people who depend on the rapidly diminishing source of fresh water. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  20. Moments of catchment storm area

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.; Wang, Q.

    1985-01-01

    The portion of a catchment covered by a stationary rainstorm is modeled by the common area of two overlapping circles. Given that rain occurs within the catchment and conditioned by fixed storm and catchment sizes, the first two moments of the distribution of the common area are derived from purely geometrical considerations. The variance of the wetted fraction is shown to peak when the catchment size is equal to the size of the predominant storm. The conditioning on storm size is removed by assuming a probability distribution based upon the observed fractal behavior of cloud and rainstorm areas.

  1. Centralized Storm Information System (CSIS)

    NASA Technical Reports Server (NTRS)

    Norton, C. C.

    1985-01-01

    A final progress report is presented on the Centralized Storm Information System (CSIS). The primary purpose of the CSIS is to demonstrate and evaluate real time interactive computerized data collection, interpretation and display techniques as applied to severe weather forecasting. CSIS objectives pertaining to improved severe storm forecasting and warning systems are outlined. The positive impact that CSIS has had on the National Severe Storms Forecast Center (NSSFC) is discussed. The benefits of interactive processing systems on the forecasting ability of the NSSFC are described.

  2. Effects of cAMP modulators on long-chain fatty-acid uptake and utilization by electrically stimulated rat cardiac myocytes.

    PubMed Central

    Luiken, J J F P; Willems, J; Coort, S L M; Coumans, W A; Bonen, A; Van Der Vusse, G J; Glatz, J F C

    2002-01-01

    Recently, we established that cellular contractions increase long-chain fatty-acid (FA) uptake by cardiac myocytes. This increase is dependent on the transport function of an 88 kDa membrane FA transporter, FA translocase (FAT/CD36), and, in analogy to skeletal muscle, is likely to involve its translocation from an intracellular pool to the sarcolemma. In the present study, we investigated whether cAMP-dependent signalling is involved in this translocation process. Isoproterenol, dibutyryl-cAMP and the phosphodiesterase (PDE) inhibitor, amrinone, which markedly raised the intracellular cAMP level, did not affect cellular FA uptake, but influenced the fate of intracellular FAs by directing these to mitochondrial oxidation in electrostimulated cardiac myocytes. The PDE inhibitors 3-isobutyl-1-methylxanthine, milrinone and dipyridamole each significantly stimulated FA uptake as well as intracellular cAMP levels, but these effects were quantitatively unrelated. The stimulatory effects of these PDE inhibitors were antagonized by sulpho- N -succinimidylpalmitate, indicating the involvement of FAT/CD36, albeit that the different PDE inhibitors use different molecular mechanisms to stimulate FAT/CD36-mediated FA uptake. Notably, 3-isobutyl-1-methylxanthine and milrinone increased the intrinsic activity of FAT/CD36, possibly through its covalent modification, and dipyridamole induces translocation of FAT/CD36 to the sarcolemma. Elevation of intracellular cGMP, but not of cAMP, by the PDE inhibitor zaprinast did not have any effect on FA uptake and metabolism by cardiac myocytes. The stimulatory effects of PDE inhibitors on cardiac FA uptake should be considered when applying these agents in clinical medicine. PMID:12093365

  3. Calmodulin 2 Mutation N98S Is Associated with Unexplained Cardiac Arrest in Infants Due to Low Clinical Penetrance Electrical Disorders

    PubMed Central

    Jiménez-Jáimez, Juan; Palomino Doza, Julián; Ortega, Ángeles; Macías-Ruiz, Rosa; Perin, Francesca; Rodríguez-Vázquez del Rey, M. Mar; Ortiz-Genga, Martín; Monserrat, Lorenzo; Barriales-Villa, Roberto; Blanca, Enrique; Álvarez, Miguel; Tercedor, Luis

    2016-01-01

    Background Calmodulin 1, 2 and 3 (CALM) mutations have been found to cause cardiac arrest in children at a very early age. The underlying aetiology described is long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT) and idiopathic ventricular fibrillation (IVF). Little phenotypical data about CALM2 mutations is available. Objectives The aim of this paper is to describe the clinical manifestations of the Asn98Ser mutation in CALM2 in two unrelated children in southern Spain with apparently unexplained cardiac arrest/death. Methods Two unrelated children aged 4 and 7, who were born to healthy parents, were studied. Both presented with sudden cardiac arrest. The first was resuscitated after a VF episode, and the second died suddenly. In both cases the baseline QTc interval was within normal limits. Peripheral blood DNA was available to perform targeted gene sequencing. Results The surviving 4-year-old girl had a positive epinephrine test for LQTS, and polymorphic ventricular ectopic beats were seen on a previous 24-hour Holter recording from the deceased 7-year-old boy, suggestive of a possible underlying CPVT phenotype. A p.Asn98Ser mutation in CALM2 was detected in both cases. This affected a highly conserved across species residue, and the location in the protein was adjacent to critical calcium binding loops in the calmodulin carboxyl-terminal domain, predicting a high pathogenic effect. Conclusions Human calmodulin 2 mutation p.Asn98Ser is associated with sudden cardiac death in childhood with a variable clinical penetrance. Our results provide new phenotypical information about clinical behaviour of this mutation. PMID:27100291

  4. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended...

  5. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended...

  6. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended...

  7. Polar and equatorial ionosphere interaction during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Biktash, L.

    The solar wind-magnetosphere-ionosphere coupling as applied to the polar and equatorial ionosphere dynamics is examined. To do this simultaneous observations of the IMF, ground-based measurements of the ionospheric parameters and geomagnetic field variations from the high latitudes to the equator are used during magnetic storms. It is shown that the auroral electric fields during magnetically disturbed conditions by the magnetospheric current systems can play a dominant role in the equatorial ionosphere processes. During magnetic storms the equatorial ionosphere parameters h'F, foF2 and etc. widely deviated from quiet day conditions and different kinds of ionospheric irregularities are formed. The equatorial ionospheric irregularities manifest as spread F in ionograms, reversals of drift velocities, scintillation of radio transmissions through the ionosphere, etc. These phenomena can interpret as the result of direct penetration of electric fields from the high latitude field-aligned currents (FAC) to the equatorial ionosphere. Model of direct penetration of FAC electric field of Polar Regions 1 and Region 2, which are controlled by the solar wind, to the equatorial ionosphere is presented. From this model the solar wind electric field through the FAC is likely to the factor wich generate or inhibit the equatorward penetration of the high latitude electric field. We demonstrate that the model is suitable to explain h'F, foF2 variations and scintillation activity during geomagnetic storms. Taking into account of the equatorial and auroral electric fields coupling, relationship, between these regions can be useful to study difficult auroral conditions during magnetic storms.

  8. Neonatal thyroid storm accompanied with severe anaemia.

    PubMed

    Cao, Lu-Ying; Wei, Hong; Wang, Zheng-Li

    2015-07-01

    Neonatal thyroid storm is rare; the diagnostic criteria and management of neonatal thyroid storm have not been well established. In this paper, we report a preterm infant diagnosed with neonatal hyperthyroidism secondary to maternal Graves' disease who was discharged after therapy. Unfortunately, he was rehospitalised for neonatal thyroid storm. We will discuss the diagnosis and general therapy of neonatal thyroid storm.

  9. The Radiation Belt Storm Probes

    NASA Video Gallery

    The Radiation Belt Storm Probe mission (RBSP) will explore the Van Allen Radiation Belts in the Earth's magnetosphere. The charge particles in these regions can be hazardous to both spacecraft and ...

  10. Storm Water Management Model (SWMM)

    EPA Pesticide Factsheets

    EPA's Storm Water Management Model (SWMM) is used throughout the world for planning, analysis and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas.

  11. Cloudsat Dissects Tropical Storm Ileana

    NASA Video Gallery

    NASA's CloudSat satellite's Cloud Profiling Radar captured a sideways look across Tropical Storm Ileana on Aug. 27 at 20:40 UTC. The colors indicate intensity of reflected radar energy. The blue ar...

  12. Satellite Animation Shows California Storms

    NASA Video Gallery

    This animation of visible and infrared imagery from NOAA's GOES-West satellite shows a series of moisture-laden storms affecting California from Jan. 6 through Jan. 9, 2017. TRT: 00:36 Credit: NASA...

  13. Tropical Storm Faxai's Rainfall Rates

    NASA Video Gallery

    This animation shows Tropical Storm Faxai's rainfall rates on March 2 from a TRMM TMI/PR rainfall analysis being faded in over infrared cloud data from the TRMM VIRS instrument. Credit: SSAI/NASA, ...

  14. Winter Storms and Extreme Cold

    MedlinePlus

    ... Us Social Media Contact Us FAQS Publications Emergency Alerts Home Search × Close Search Enter Search Term(s): Languages × ... take when you receive a winter weather storm alert from the National Weather Service for your local ...

  15. Storm and Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Yesterday's storm front was moving westward, today's moves eastward. Note the thick cloud cover and beautifully delineated cloud tops.

    Image information: VIS instrument. Latitude 72.1, Longitude 308.3 East (51.7 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. Riding the storm out

    NASA Astrophysics Data System (ADS)

    Wurman, Josh

    2009-04-01

    I am standing on a bridge near the North Carolina coast. There is a light breeze, and I am enjoying some hazy sunshine. But this calm is an illusion: in a few minutes winds of up to 45ms-1 (100 mph) will sweep in again. The approaches to my section of the bridge are already drowned under 2.5 m of water, and my companions on this island are an eclectic mix of traumatized animals, including snakes, rats, wounded pelicans and frogs. Earlier, one of the snakes flew through the air past my truck. The animals and I have been drawn to this bridge by Hurricane Isabel, which has just slammed into the coastal islands of North Carolina, and at the moment we are in the calm, sunny eye of the storm. The animals are just trying to survive on the area's only dry ground. But I have come to the bridge with a radar system on a truck and have spent a night and a day on it because I want to know what is happening inside this hurricane.

  17. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

  18. Venturing into ventricular arrhythmia storm: a systematic review and meta-analysis.

    PubMed

    Nayyar, Sachin; Ganesan, Anand N; Brooks, Anthony G; Sullivan, Thomas; Roberts-Thomson, Kurt C; Sanders, Prashanthan

    2013-02-01

    Ablation has substantial evidence base in the management of ventricular arrhythmia (VA). It can be a 'lifesaving' procedure in the acute setting of VA storm. Current reports on ablation in VA storm are in the form of small series and have relative small representation in a large observational series. The purpose of this study was to systematically synthesize the available literature to appreciate the efficacy and safety of ablation in the setting of VA storm. The medical electronic databases through 31 January 2012 were searched. Ventricular arrhythmia storm was defined as recurrent (≥ 3 episodes or defibrillator therapies in 24 h) or incessant (continuous >12 h) VA. Studies reporting data on VA storm patients at the individual or study level were included. A total of 471 VA storm patients from 39 publications were collated for the analysis. All VAs were successfully ablated in 72% [95% confidence interval (CI) 71-89%] and 9% (95% CI: 3-10%) had a failed procedure. Procedure-related mortality occurred in three patients (0.6%). Only 6% patients had a recurrence of VA storm. The recurrence of VA was significantly higher after ablation for arrhythmic storm of monomorphic ventricular tachycardia (VT) relative to ventricular fibrillation or polymorphic VT with underlying cardiomyopathy (odds ratio 3.76; 95% CI: 1.65-8.57; P = 0.002). During the follow-up (61 ± 37 weeks), 17% of patients died (heart failure 62%, arrhythmias 23%, and non-cardiac 15%) with 55% deaths occurring within 12 weeks of intervention. The odds of death were four times higher after a failed procedure compared with those with a successful procedure (95% CI: 2.04-8.01, P < 0.001). Ventricular arrhythmia storm ablation has high-acute success rates, with a low rate of recurrent storms. Heart failure is the dominant cause of death in the long term. Failure of the acute procedure carries a high mortality.

  19. Positive and negative ionospheric responses to the March 2015 geomagnetic storm from BDS observations

    NASA Astrophysics Data System (ADS)

    Jin, Shuanggen; Jin, Rui; Kutoglu, H.

    2017-01-01

    The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI [O]/[N2] ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm.

  20. Impact of famous CEDAR, GEM and ISTP geomagnetic Storms on HF Radio Propagation

    NASA Astrophysics Data System (ADS)

    Blagoveshchensky, D.; Sergeeva, M.

    The mighty geomagnetic storms due to the extraordinary Sun s activity cause as a rule some impacts in these areas radiation effects on human and satellites commercial airlines outages electric power and other geomagnetic effects navigation and communication GPS effects ionospheric disturbances HF communication effects Therefore our scientific understanding of this activity is very important Joint efforts for example within the framework of the CAWSES enable progress in our ability to i identify critical inputs to specify the geospace environment at a level needed to minimize impacts on technology human society and life and ii support the development of robust models that predict conditions in geospace based on understanding of the Sun-Earth system and all of its interacting components In this study influence of 14 geomagnetic storms from a list of CEDAR GEM and ISTP storms within 1997-99 on radio propagation conditions have been investigated These conditions were estimated through variations of the MOF and LOF the maximum and lowest operation frequencies on each path from three high-latitude HF radio paths of North-west Russia before during and after a storm It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character Nevertheless the common character of the certain manifestations during storm-time was revealed For example the frequency range MOF - LOF is getting wider several hours before a storm then it is sharply narrow during a storm-time and further it is expanded again several

  1. Energy and Mass Transport of Magnetospheric Plasmas during the November 2003 Magnetic Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Chging; Moore, Thomas

    2008-01-01

    Intensive energy and mass transport from the solar wind across the magnetosphere boundary is a trigger of magnetic storms. The storm on 20-21 November 2003 was elicited by a high-speed solar wind and strong southward component of interplanetary magnetic field. This storm attained a minimum Dst of -422 nT. During the storm, some of the solar wind particles enter the magnetosphere and eventually become part of the ring current. At the same time, the fierce solar wind powers strong outflow of H+ and O+ from the ionosphere, as well as from the plasmasphere. We examine the contribution of plasmas from the solar wind, ionosphere and plasmasphere to the storm-time ring current. Our simulation shows, for this particular storm, ionospheric O+ and solar wind ions are the major sources of the ring current particles. The polar wind and plasmaspheric H+ have only minor impacts. In the storm main phase, the strong penetration of solar wind electric field pushes ions from the geosynchronous orbit to L shells of 2 and below. Ring current is greatly intensified during the earthward transport and produces a large magnetic depression in the surface field. When the convection subsides, the deep penetrating ions experience strong charge exchange loss, causing rapid decay of the ring current and fast initial storm recovery. Our simulation reproduces very well the storm development indicated by the Dst index.

  2. Different behavior of storm-time themospheric mass density response to merging E field for different type of magnetic storms

    NASA Astrophysics Data System (ADS)

    Ma, S. Y.; Zhou, Yunliang; Liu, Ruosi

    With the help of GRACE accelerometer observations and the solar wind and IMF OMNI data, a statistical investigation has been made on the relationships of merging electrical field, Em, with the storm-time changes in the upper thermospheric mass density for 35 great storms during 2002-2006. The linear control factors of Em on the storm-time changes of both mass density and its algorithm are examined, along with the delay times of density changes behind Em. The dependences of the control factors on the latitude and local time are investigated for different storm types. It is found that the influences of Em on the storm-time mass densities characterized by nonlinear control factors show different behavior for different types of storms. The influence intensity of Em on mass density is stronger for CIR-driven than for CME-driven storms, manifested as 2.7 times for CME-driven over CIR driven storm at dawn sector. In terms of the ratio of influence factor for CIR over CME, there is a larger intensification in dawn/dusk sector than in noon/midnight sector clearly. Besides, it is very interesting that, except for noon sector, the delay times of mass density changes in respect to Em at low latitudes are shorter than at mid-latitudes. This phenomenon seems in contravention of high latitude origin of mass density changes and consequent propagation equatorward. We surmise that this may imply some additional heating or disturbance sources rather than high latitude origin at working for low and/or mid-latitude mass density changes. One possible source is energetic neutral atom (ENA) precipitation of storm-time ring current origin caused by charge exchange between energetic RC (ring current) ions and cold atoms of geo-corona, another may be the coupling between low-latitude thermosphere and ionosphere associated with prompt penetration of interplanetary electric field that has larger penetration efficiency during night. Acknowledgements: Many thanks to Prof. Luehr for useful

  3. Electrification in winter storms and the analysis of thunderstorm overflight

    NASA Technical Reports Server (NTRS)

    Brook, Marx

    1991-01-01

    The emergence of 24 hr operational lightning detection networks has led to the finding that positive lightning strokes, although still much fewer in number than the normal negative strokes, are present in summer and winter storms. Recent papers address the importance of understanding the meteorological conditions which lead to a dominance of one polarity of stroke over another; the appearance of positive strokes at the end of a storm appeared to presage the end-of-storm downdraft and subsidence leading to downburst activity. It is beginning to appear that positive strokes may be important meteorological indicators. Significant research accomplishments on the following topics are addressed: (1) a study to verify that the black boxes used in the lightning networks to detect both negative and positive strokes to ground were accurate; (2) the use of slow tails to determine the polarity of distant lightning; (3) lightning initiation in winter vs. summer storms; (4) the upgrade of sensors for the measurement of electric field signals associated with lightning; (5) the analysis of lightning flash records from storms between 40 and 125 km from the sensor; and (6) an interesting aspect of the initiation process which involves the physical processes driving the stepped leader. The focus of current research and future research plans are presented.

  4. Cardiac Rehabilitation

    MedlinePlus

    ... your risk of future heart problems, and to improve your health and quality of life. Cardiac rehabilitation programs increase ... exercise routine at home or at a local gym. You may also continue to ... health concerns. Education about nutrition, lifestyle and weight loss ...

  5. Sudden cardiac death: A reappraisal.

    PubMed

    Steinberg, Christian; Laksman, Zachary W M; Krahn, Andrew D

    2016-11-01

    Sudden cardiac death (SCD) is still among the leading causes of death in women and men, accounting for over 50% of all fatal cardiovascular events in the United States. Two arrhythmia mechanisms of SCD can be distinguished as follows: shockable rhythms (ventricular fibrillation and pulseless ventricular tachycardia) and non-shockable rhythms including asystole or pulseless electrical activity. The overall prognosis of cardiac arrest due to shockable rhythms is significantly better. While the majority of SCDs is attributed to coronary artery disease or other structural heart disease, no obvious cause can be identified in 5% of all events, and those events are labeled as sudden unexplained deaths (SUD). Those unexplained events are typically caused by rare hereditary electrical disorders or arrhythmogenic cardiomyopathies. A systematic approach to the diagnosis of cardiac arrest followed by tailored therapy based on etiology has emerged in the last 10-15 years, with significant changes of medical practice and risk management of cardiac arrest victims. The aim of this review is to summarize our contemporary understanding of SCD/SUD in adults and to discuss current concepts of management and secondary prevention in cardiac arrest victims. A full discussion of the topic of primary prevention of SCD is beyond the scope of this article.

  6. A model model: a commentary on DiFrancesco and Noble (1985) ‘A model of cardiac electrical activity incorporating ionic pumps and concentration changes’

    PubMed Central

    Dibb, Katharine; Trafford, Andrew; Zhang, Henggui; Eisner, David

    2015-01-01

    This paper summarizes the advances made by the DiFrancesco and Noble (DFN) model of cardiac cellular electrophysiology, which was published in Philosophical Transactions B in 1985. This model was developed at a time when the introduction of new techniques and provision of experimental data had resulted in an explosion of knowledge about the cellular and biophysical properties of the heart. It advanced the cardiac modelling field from a period when computer models considered only the voltage-dependent channels in the surface membrane. In particular, it included a consideration of changes of both intra- and extracellular ionic concentrations. In this paper, we summarize the most important contributions of the DiFrancesco and Noble paper. We also describe how computer modelling has developed subsequently with the extension from the single cell to the whole heart as well as its use in understanding disease and predicting the effects of pharmaceutical interventions. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society. PMID:25750236

  7. Solar Energetic Particle Trapping During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Hudson, M.; Kress, B.; Blake, J. B.; Mazur, J.

    2007-12-01

    The prompt trapping of Solar Energetic Particles (SEPs) in the inner magnetosphere inside of L = 4 has been reported, including protons and heavier ions, in association with high speed interplanetary shocks and Storm Sudden Commencements (SSCs). These observations include the Bastille Day 2000 CME-driven storm as well as two in November 2001, which produced a long-lived new proton belt, as well as trapping of heavy ions up to Fe in all three cases. A survey of such events around the most recent solar maximum, including high altitude measurements from Polar, HEO and ICO satellites along with low altitude measurements from SAMPEX, indicates similarities to the well-studied March 24, 1991 SSC event. In this event, electrons and protons in drift resonance with a magnetosonic impulse were transported radially inward, requiring a source population which is multi-MeV at geosynchronous. A requirement for such shock-induced acceleration is a high-speed CME- shock at 1 AU, which launches a perturbation with comparable velocity inside the magnetosphere. Secondly, there must be a source population which is drift-resonant with the impulse. The CME-shock itself is a source of solar energetic particles, both protons and heavy ions, with higher fluxes and harder spectra associated with faster moving CMEs. A 3D Lorentz integration of SEP trajectories in electric and magnetic fields taken from the Lyon-Fedder-Mobarry (LFM) global MHD model, using solar wind input parameters from spacecraft measurements upstream from the bow shock, has been carried out for two November, 2001 SEP trapping events, and a CME-shock associated with the Halloween 2003 storm period, 29 October, which transported outer zone electrons and trapped solar energetic electrons into around L = 2.5, with little effect on SEPs. These results indicate that an enhancement in solar wind dynamic pressure for these events plays a role in the observed injection of ions (and electrons) to low L-values, as does the extent of

  8. The 17 March 2015 storm: the associated magnetic flux rope structure and the storm development

    NASA Astrophysics Data System (ADS)

    Marubashi, Katsuhide; Cho, Kyung-Suk; Kim, Rok-Soon; Kim, Sujin; Park, Sung-Hong; Ishibashi, Hiromitsu

    2016-11-01

    The objective of this study is (1) to determine the magnetic cloud (MC) structure associated with the 17 March 2015 storm and (2) to gain an insight into how the storm developed responding to the solar wind conditions. First, we search MC geometries which can explain the observed solar wind magnetic fields by fitting to both cylindrical and toroidal flux rope models. Then, we examine how the resultant MC geometries can be connected to the solar source region to find out the most plausible model for the observed MC. We conclude that the observations are most consistently explained by a toroidal flux rope with the torus plane nearly parallel to the ecliptic plane. It is emphasized that the observations are characterized by the peculiar spacecraft crossing through the MC, in that the magnetic fields to be observed are southward throughout the passage. For understanding of the storm development, we first estimate the injection rate of the storm ring current from the observed Dst variation. Then, we derive an expression to calculate the estimated injection rate from the observed solar wind variations. The point of the method is to evaluate the injection rate by the convolution of the dawn-to-dusk electric field in the solar wind and a response function. By using the optimum response function thus determined, we obtain a modeled Dst variation from the solar wind data, which is in good agreement with the observed Dst variation. The agreement supports the validity of our method to derive an expression for the ring current injection rate as a function of the solar wind variation.[Figure not available: see fulltext.

  9. New forecasting methods of the intensity and time development of geomagnetic and ionospheric storms

    NASA Astrophysics Data System (ADS)

    Akasofu, S.-I.

    The main phase of a geomagnetic storm develops differently from one storm to another. A description is given of the solar wind quantity which controls directly the development of the main phase of geomagnetic storms. The parameters involved include the solar wind speed, the magnetic field intensity, and the polar angle of the solar wind magnetic field projected onto the dawn-dusk plane. A redefinition of geomagnetic storm and auroral activity is given. It is pointed out that geomagnetic disturbances are caused by the magnetic fields of electric currents which are generated by the solar wind-magnetosphere dynamo. Attention is given to approaches for forecasting the occurrence and intensity of geomagnetic storms and ionospheric disturbances.

  10. On the Variability of Wilson Currents by Storm Type and Phase

    NASA Technical Reports Server (NTRS)

    Deierling, Wiebke; Kalb, Christina; Mach, Douglas; Liu, Chuntao; Peterson, Michael; Blakeslee, Richard

    2014-01-01

    Storm total conduction currents from electrified clouds are thought to play a major role in maintaining the potential difference between the earth's surface and the upper atmosphere within the Global Electric Circuit (GEC). However, it is not entirely known how the contributions of these currents vary by cloud type and phase of the clouds life cycle. Estimates of storm total conduction currents were obtained from data collected over two decades during multiple field campaigns involving the NASA ER-2 aircraft. In this study the variability of these currents by cloud type and lifecycle is investigated. We also compared radar derived microphysical storm properties with total storm currents to investigate whether these storm properties can be used to describe the current variability of different electrified clouds. The ultimate goal is to help improve modeling of the GEC via quantification and improved parameterization of the conduction current contribution of different cloud types.

  11. SAMI3-RCM simulation of the 17 March 2015 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Huba, J. D.; Sazykin, S.; Coster, A.

    2017-01-01

    We present a self-consistent modeling study of the ionosphere-plasmasphere system response to the 17 March 2015 geomagnetic storm using the coupled SAMI3-RCM code. The novel feature of this work is that we capture the important storm time dynamics of the ionosphere on a global scale and its manifestation in the plasmasphere. We find that the penetration electric fields associated with the magnetic storm lead to a storm time enhanced density in the low- to middle-latitude ionosphere. We compare the modeled total electron content (TEC) with GPS-measured TEC in the American sector. Additionally, we observe the development of polar cap "tongues of ionization" and the formation of subauroral plasma streams in the postsunset, premidnight sector, and its impact on the plasmasphere. However, we did not see the development of plasmaspheric plumes during this event which we attribute to the long main phase of the storm (˜18 h).

  12. Ring Current Development During Storm Main Phase

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, Thomas E.; Greenspan, Marian E.

    1996-01-01

    The development of the ring current ions in the inner magnetosphere during the main phase of a magnetic storm is studied. The temporal and spatial evolution of the ion phase space densities in a dipole field are calculated using a three dimensional ring current model, considering charge exchange and Coulomb losses along drift paths. The simulation starts with a quiet time distribution. The model is tested by comparing calculated ion fluxes with Active Magnetospheric Particle Tracer Explorers/CCE measurement during the storm main phase on May 2, 1986. Most of the calculated omnidirectional fluxes are in good agreement with the data except on the dayside inner edge (L less than 2.5) of the ring current, where the ion fluxes are underestimated. The model also reproduces the measured pitch angle distributions of ions with energies below 10 keV. At higher energy, an additional diffusion in pitch angle is necessary in order to fit the data. The role of the induced electric field on the ring current dynamics is also examined by simulating a series of substorm activities represented by stretching and collapsing the magnetic field lines. In response to the impulsively changing fields, the calculated ion energy content fluctuates about a mean value that grows steadily with the enhanced quiescent field.

  13. Mechanical cardiac assistance.

    PubMed

    Sezai, Y

    1998-08-01

    In our institute, we have intensively introduced both pulsatile and non-pulsatile mechanical cardiac assist devices, such as the pneumatic ventricular assist device (VAD) and percutaneous cardiopulmonary support (PCPS), using a centrifugal pump. From various kinds of clinical views, these cases were estimated and evaluated retrospectively according to the weaning results, long-term survival rate and cause of death. Based upon our experiences and clinical results, an alternate strategy of mechanical cardiac assistance for severe heart failure is suggested as follows. In the case of post-cardiotomy cardiogenic shock or low output syndrome, PCPS system should be applied firstly under intra-aortic balloon pumping (IABP) assist for a maximum of 2-3 days. If the native cardiac function does not recover and more long-term support is needed, several types of VAD, which are more powerful and durable devices should be introduced, according to end organ function and expected support duration. In order to obtain better clinical results, we have to select an appropriate device depending on the limited availability of supporting duration. Generally speaking, centrifugal pumps can support in short-term duration, while pulsatile devices cover the broad spectrum of the supporting period. Pneumatic VADs can cover short-term to long-term support up to a year, and electric VADs can cover over 1 year, and can be used as a bridge to heart transplantation.

  14. Storm tracks near marginal stability

    NASA Astrophysics Data System (ADS)

    Ambaum, Maarten; Novak, Lenka

    2015-04-01

    The variance of atmospheric storm tracks is characterised by intermittent bursts of activity interspersed with relatively quiescent periods. Most of the poleward heat transport by storm tracks is due to a limited number of strong heat flux events, which occur in a quasi-periodic fashion. This behaviour is in contradiction with the usual conceptual model of the storm tracks, which relies on high growth rate background flows which then spawn weather systems that grow in an exponential or non-normal fashion. Here we present a different conceptual model of the atmospheric storm tracks which is built on the observation that, when including diabatic and other dissipative effects, the storm track region is in fact most of the time marginally stable. The ensuing model is a nonlinear oscillator, very similar to Volterra-Lotka predator-prey models. We demonstrate the extensions of this model to a stochastically driven nonlinear oscillator. The model produces quasi-periodic behaviour dominated by intermittent heat flux events. Perhaps most surprisingly, we will show strong evidence from re-analysis data for our conceptual model: the re-analysis data produces a phase-space plot that is very similar indeed to the phase-space plot for our nonlinear oscillator model.

  15. Tropical Storms Bud and Dera

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Like dancers pirouetting in opposite directions, the rotational patterns of two different tropical storms are contrasted in this pair of MISR nadir-camera images.

    The left-hand image is of Tropical Storm Bud, acquired on June 17, 2000 (Terra orbit 2656) as the storm was dissipating. Bud was situated in the eastern Pacific Ocean between Socorro Island and the southern tip of Baja California. South of the storm's center is a vortex pattern caused by obstruction of the prevailing flow by tiny Socorro Island. Sonora, Mexico and Baja California are visible at the top of the image.

    The right-hand image is of Tropical Cyclone Dera, acquired on March 12, 2001 (Terra orbit 6552). Dera was located in the Indian Ocean, south of Madagascar. The southern end of this large island is visible in the top portion of this image.

    Northern hemisphere tropical storms, like Bud, rotate in a counterclockwise direction, whereas those in the southern hemisphere, such as Dera, rotate clockwise. The opposite spins are a consequence of Earth's rotation.

    Each image covers a swath approximately 380 kilometers wide.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  16. Tropical Storms Bud and Dera

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Like dancers pirouetting in opposite directions, the rotational patterns of two different tropical storms are contrasted in this pair of Multi-angle Imaging Spectroradiometer (MISR) nadir-camera images. The left-hand image is of Tropical Storm Bud, acquired on June 17, 2000 (Terra orbit 2656) as the storm was dissipating. Bud was situated in the eastern Pacific Ocean between Socorro Island and the southern tip of Baja California. South of the storm's center is a vortex pattern caused by obstruction of the prevailing flow by tiny Socorro Island. Sonora, Mexico and Baja California are visible at the top of the image. The right-hand image is of Tropical Cyclone Dera, acquired on March 12, 2001. Dera was located in the Indian Ocean, south of Madagascar. The southern end of this large island is visible in the top portion of this image. Northern hemisphere tropical storms, like Bud, rotate in a counterclockwise direction, whereas those in the southern hemisphere, such as Dera, rotate clockwise. The opposite spins are a consequence of Earth's rotation. Each image covers a swath approximately 380 kilometers wide. Image courtesy NASA/JPL/GSFC/LaRC, MISR Team

  17. Physics of Cardiac Arrhythmogenesis

    NASA Astrophysics Data System (ADS)

    Karma, Alain

    2013-04-01

    A normal heartbeat is orchestrated by the stable propagation of an excitation wave that produces an orderly contraction. In contrast, wave turbulence in the ventricles, clinically known as ventricular fibrillation (VF), stops the heart from pumping and is lethal without prompt defibrillation. I review experimental, computational, and theoretical studies that have shed light on complex dynamical phenomena linked to the initiation, maintenance, and control of wave turbulence. I first discuss advances made to understand the precursor state to a reentrant arrhythmia where the refractory period of cardiac tissue becomes spatiotemporally disordered; this is known as an arrhythmogenic tissue substrate. I describe observed patterns of transmembrane voltage and intracellular calcium signaling that can contribute to this substrate, and symmetry breaking instabilities to explain their formation. I then survey mechanisms of wave turbulence and discuss novel methods that exploit electrical pacing stimuli to control precursor patterns and low-energy pulsed electric fields to control turbulence.

  18. Cardiac Surgery

    PubMed Central

    Weisse, Allen B.

    2011-01-01

    Well into the first decades of the 20th century, medical opinion held that any surgical attempts to treat heart disease were not only misguided, but unethical. Despite such reservations, innovative surgeons showed that heart wounds could be successfully repaired. Then, extracardiac procedures were performed to correct patent ductus arteriosus, coarctation of the aorta, and tetralogy of Fallot. Direct surgery on the heart was accomplished with closed commissurotomy for mitral stenosis. The introduction of the heart-lung machine and cardiopulmonary bypass enabled the surgical treatment of other congenital and acquired heart diseases. Advances in aortic surgery paralleled these successes. The development of coronary artery bypass grafting greatly aided the treatment of coronary heart disease. Cardiac transplantation, attempts to use the total artificial heart, and the application of ventricular assist devices have brought us to the present day. Although progress in the field of cardiovascular surgery appears to have slowed when compared with the halcyon times of the past, substantial challenges still face cardiac surgeons. It can only be hoped that sufficient resources and incentive can carry the triumphs of the 20th century into the 21st. This review covers past developments and future opportunities in cardiac surgery. PMID:22163121

  19. The need to immobilise the cervical spine during cardiopulmonary resuscitation and electric shock administration in out-of-hospital cardiac arrest.

    PubMed

    Desroziers, Milene; Mole, Sophie; Jost, Daniel; Tourtier, Jean-Pierre

    2016-06-13

    In cases of out-of hospital cardiac arrest (OHCA), falling to the ground can cause brain and neck trauma to the patient. We present a case of a man in his mid-60s who suffered from an OHCA resulting in a violent collapse. The patient received immediate cardiopulmonary resuscitation, but his spine was immobilised only after a large frontal haematoma was found. The resuscitation efforts resulted in return of spontaneous circulation and discharge from hospital. After this, doctors performed angioplasty, followed by a cardiopulmonary bypass. Later, CT scan examination reported a displaced and unstable fracture of the 6th vertebra without bone marrow involvement. The patient underwent a second operation. 40 days later, he was able to return home without sequela. This case shows the importance of analysing the circumstances of a fall, considering the possibility of two concomitant diagnoses and prioritising investigations and treatment.

  20. Radiation Belt Storm Probe (RBSP) Mission

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Fox, N.; Grebowsky, J. M.; Mauk, B. H.

    2009-01-01

    Scheduled to launch in May 2012, NASA's dual spacecraft Living With a Star Radiation Belt Storm Probe mission carries the field and particle instrumentation needed to determine the processes that produce enhancements in radiation belt ion and electron fluxes, the dominant mechanisms that cause the loss of relativistic electrons, and the manner by which the ring current and other geomagnetic phenomena affect radiation belt behavior. The two spacecraft will operate in low-inclination elliptical lapping orbits around the Earth, within and immediately exterior to the Van Allen radiation belts. During course of their two year primary mission, they will cover the full range of local times, measuring both AC and DC electric and magnetic fields to 10kHz, as well as ions from 50 eV to 1 GeV and electrons with energies ranging from 50 eV to 10 MeV.

  1. The ice storm of the century: how affected hospitals and communities dealt with the challenges of a unique, prolonged emergency.

    PubMed

    1998-04-01

    A huge ice storm in early January 1998 caused severe damage in northern New York and parts of Maine and Canada. The storm, which lasted in some areas for several weeks and is being called the "storm of the century," led to 30 deaths (many from carbon monoxide poisoning); closed roads and schools; downed thousand of trees and power lines; and left hundreds of thousands without electricity. In this report, we'll present details on how hospitals in these three locations which were declared disaster areas were affected by the storm as well as the measures that they and their security departments took to help patients, staff, and their communities.

  2. Springtime North Polar Dust Storms

    NASA Technical Reports Server (NTRS)

    2002-01-01

    MGS MOC Release No. MOC2-321, 12 December 2002

    As on the Earth, many severe storms brew in the martian polar regions. Here, temperature contrasts between the cold carbon dioxide ('dry ice') seasonal frost cap and the warm ground adjacent to it--combined with a flow of cool polar air evaporating off the cap--sweeps up dust and funnels it into swirling dust storms along the cap edge. The dust storms shown here were observed during the recent northern spring by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2002. The picture is a mosaic of daily global images from the MOC wide angle cameras. The north polar cap is the bright, frosty surface at the top.

  3. Agents to reduce cytokine storm.

    PubMed

    Gerlach, Herwig

    2016-01-01

    The increasing insight into pathomechanisms of dysregulated host response in several inflammatory diseases led to the implementation of the term "cytokine storm" in the literature more than 20 years ago. Direct toxic effects as well as indirect immunomodulatory mechanisms during cytokine storm have been described and were the basis for the rationale to use several substances and devices in life-threatening infections and hyperinflammatory states. Clinical trials have been performed, most of them in the form of minor, investigator-initiated protocols; major clinical trials focused mostly on sepsis and septic shock. The following review tries to summarize the background, pathophysiology, and results of clinical investigations that had implications for the development of therapeutic strategies and international guidelines for the management of hyperinflammation during syndromes of cytokine storm in adult patients, predominantly in septic shock.

  4. Investigating repeatable ionospheric features during large space storms and superstorms

    DTIC Science & Technology

    2014-08-25

    Final 3. DATES COVERED (From - To) Mar-13 – Jan-14 4. TITLE AND SUBTITLE Investigating repeatable ionospheric features during large... Ionosphere -Plasmasphere Electrodynamics). The 6 April 2000 superstorm (Dst = -314 nT) was complex as the prompt penetration electric field developed and...event because of its unusual pattern producing unusual ionospheric storms. Our results reveal some strong longitudinal differences caused by the

  5. Mesoscale aspects of convective storms

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.

    1981-01-01

    The structure, evolution and mechanisms of mesoscale convective disturbances are reviewed and observation techniques for "nowcasting" their nature are discussed. A generalized mesometeorological scale is given, classifying both low and high pressure systems. Mesoscale storms are shown often to induce strong winds, but their wind speeds are significantly less than those accompanied by submesoscale disturbances, such as tornadoes, downbursts, and microbursts. Mesoscale convective complexes, severe storm wakes, and flash floods are considered. The understanding of the evolution of supercells is essential for improving nowcasting capabilities and a very accurate combination of radar and satellite measurements is required.

  6. National Severe Storms Forecast Center

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The principal mission of the National Severe Storms Forecast Center (NSSFC) is to maintain a continuous watch of weather developments that are capable of producing severe local storms, including tornadoes, and to prepare and issue messages designated as either Weather Outlooks or Tornado or Severe Thunderstorm Watches for dissemination to the public and aviation services. In addition to its assigned responsibility at the national level, the NSSFC is involved in a number of programs at the regional and local levels. Subsequent subsections and paragraphs describe the NSSFC, its users, inputs, outputs, interfaces, capabilities, workload, problem areas, and future plans in more detail.

  7. Research on Historical Records of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Lakhina, G. S.; Alex, S.; Tsurutani, B. T.; Gonzalez, W. D.

    In recent times, there has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs and concomitant magnetic storms. Magnetic storms are the most dramatic and perhaps important component of space weather effects on Earth. Super-intense magnetic storms (defined here as those with Dst < -500 nT, where Dst stands for the disturbance storm time index that measures the strength of the magnetic storm) although relatively rare, have the largest societal and technological relevance. Such storms can cause life-threatening power outages, satellite damage, communication failures and navigational problems. However, the data for such magnetic storms is rather scarce. For example, only one super-intense magnetic storm has been recorded (Dst=-640 nT, March 13, 1989) during the space-age (since 1958), although such storms may have occurred many times in the last 160 years or so when the regular observatory network came into existence. Thus, research on historical geomagnetic storms can help to create a good data base for intense and super-intense magnetic storms. From the application of knowledge of interplanetary and solar causes of storms gained from the spaceage observations applied to the super-intense storm of September 1-2, 1859, it has been possible to deduce that an exceptionally fast (and intense) magnetic cloud was the interplanetary cause of this geomagnetic storm with a Dst -1760 nT, nearly 3 times as large as that of March 13, 1989 super-intense storm. The talk will focus on super-intense storms of September 1-2, 1859, and also discuss the results in the context of some recent intense storms.

  8. Magnetospheric signature of some F layer positive storms

    SciTech Connect

    Miller, N.J.; Mayr, H.G.; Grebowsky, J.M.; Harris, I.; Tulunay, Y.K.

    1981-05-01

    Calculations using a self-consistent model of the global thermosphere-ionosphere system perturbed by high-latitude thermospheric heating show that the resultant electron density disturbances within the mid-latitude F layer can propagate upward along magnetic field lines to the equator. The F layer disturbances described by the model calculations correspond to the evolution of enhancements or reductions in electron density that is called the positive or negative phase of an F layer storm. We deduce that the positive phase of dayside F layer storms is initiated when high-latitude thermospheric heating generates equatorward winds. These winds raise the mid-latitude F layer along the geomagnetic field B through momentum transfer from neutral atoms to F layer ons that pull electrons with them. For Lapprox.3 or less the upward movement of ionospheric plasma results in ionization increases at all altitudes along B from the F2 maximum to the equator. An increase in the average magnitude of the equatorial dawn-dusk magnetospheric electric field retards the dayside development of a positive storm phase by drifting plasma away from mid-latitude field lines along which the electron density is increasing. During an F layer storm in June 1972, instruments on Explorer 45 and Ariel 4 detected dayside electron density enhancements simultaneously at 550 km over mid-latitudes and near the equatorial plane in the magnetosphere. These in situ measurements support the model prediction that disturbances in the magnetospheric plasma near the equator can arise through interactions occuring at lower altitudes along a magnetic field line. Our study demonstrates that some storm time enhancements of dayside magnetospheric plasma near Lapprox.2--3 may be signatures of the positive phase of an F layer storm.

  9. GPM Sees Powerful Storms in Tropical Storm Hermine

    NASA Video Gallery

    This is a 3-D animated flyby of Tropical Storm Hermine created using radar data from the GPM core satellite. On Aug. 31 at 4 p.m. EDT GPM found rainfall occurring at a rate of over 9.9 inches (251 ...

  10. Templates of Change: Storms and Shoreline Hazards.

    ERIC Educational Resources Information Center

    Dolan, Robert; Hayden, Bruce

    1980-01-01

    Presents results of research designed to assess and predict the storm-related hazards of living on the coast. Findings suggest that certain sections of coastline are more vulnerable than others to storm damage. (WB)

  11. Tropical Storm Debby Moves into Atlantic

    NASA Video Gallery

    An animation of satellite observations shows the progression of Tropical Storm Debby from June 25-27, 2012. The animation shows that Tropical Storm Debby's center move from the northeastern Gulf of...

  12. Satellite View of 2 Trop. Storms

    NASA Video Gallery

    System 98L exploded into Tropical Storm Irene on Saturday, August 20. This GOES-13 Video shows Tropical Storm Harvey making landfall in Belize (just beneath the Yucatan Peninsula) and moving into t...

  13. About Cardiac Arrest

    MedlinePlus

    ... Thromboembolism Aortic Aneurysm More About Cardiac Arrest Updated:Mar 10,2017 What is cardiac arrest? Cardiac arrest is the abrupt loss of heart function in a person who may or may not have diagnosed heart ...

  14. ENSO and winter storms in California

    USGS Publications Warehouse

    Cayan, D.R.; Bromirski, Peter

    2003-01-01

    The frequency and intensity of North Pacific winter storms that penetrate the California coast drives the winds, sea level, precipitation and streamflow that are crucial influences on coastal processes. There is considerable variability of these storm characteristics, in large part owing to the El Nino/Southern Oscillation (ENSO} phenomenon. There is a great contrast of the storm characteristics during the El Nino phase vs. the La Nina phase, with the largest scale, southerly extensive winter storms generated during El Nino.

  15. Rain from Tropical Storm Noel

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Though not the most powerful storm of the 2007 Atlantic Hurricane season, Tropical Storm Noel was among the most deadly. Only Category 5 Hurricane Felix and its associated flooding had a higher toll. The slow-moving Tropical Storm Noel inundated the Dominican Republic, Haiti, Jamaica, Cuba, and the Bahamas with heavy rain between October 28 and November 1, 2007. The resulting floods and mudslides left at least 115 dead and thousands homeless throughout the Caribbean, reported the Associated Press on November 2, 2007. This image shows the distribution of the rainfall that made Noel a deadly storm. The image shows rainfall totals as measured by the Multi-satellite Precipitation Analysis (MPA) at NASA Goddard Space Flight Center from October 26 through November 1, 2007. The analysis is based on measurements taken by the Tropical Rainfall Measuring Mission (TRMM) satellite. The heaviest rainfall fell in the Dominican Republic and the Bahamas, northeast of Noel's center. Areas of dark red show that rainfall totals over the south-central Dominican Republic and parts of the Bahamas were over 551 millimeters (21 inches). Much of eastern Hispaniola, including both the Dominican Republic and Haiti received at least 200 mm (about 8 inches) of rain, shown in yellow. Rainfall totals over Haiti and Cuba were less, with a range of at least 50 mm (2 inches) to over 200 mm (8 inches).

  16. Storm Water Management Model (SWMM)

    EPA Science Inventory

    Stormwater discharges continue to cause impairment of our Nation’s waterbodies. Regulations that require the retention and/or treatment of frequent, small storms that dominate runoff volumes and pollutant loads are becoming more common. The U.S. Environmental Protection Agency (E...

  17. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  18. 46 CFR 116.920 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where...

  19. 46 CFR 116.920 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where...

  20. 46 CFR 127.320 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and...

  1. 46 CFR 116.920 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where...

  2. 46 CFR 108.221 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

  3. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  4. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  5. 46 CFR 127.320 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and...

  6. 46 CFR 108.221 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

  7. 46 CFR 127.320 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and...

  8. 46 CFR 177.920 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

  9. 46 CFR 177.920 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

  10. 46 CFR 127.320 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and...

  11. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  12. 46 CFR 108.221 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

  13. 46 CFR 116.920 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where...

  14. 46 CFR 116.920 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where...

  15. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  16. 46 CFR 127.320 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and...

  17. 46 CFR 108.221 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

  18. 46 CFR 177.920 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

  19. 46 CFR 177.920 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

  20. 46 CFR 108.221 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

  1. 46 CFR 177.920 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

  2. Storm severity detection (RF)

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.; Goodman, S. J.

    1985-01-01

    Atmospheric electrical emissions occurring in association with Hurricane Alicia were observed by two crossed baseline phase linear interferometers. The sensors were located in San Antonio, Texas, and at Marshall Space Flight Center (MSFC), Huntsville, Alabama. An analysis of the data has indicated that the direction finding (DF) performance of the San Antonio site was extremely good while the DF performance at the MSFC site evidenced erratic behavior. A check of the data acquisition hardware revealed an intermitted problem in one of the radio receiver channels. Since the system has experienced several lightning strikes during the early spring of 1984, it was necessary to ship the entire rack of equipment back to SwRI for refurbishment. Analysis of the DF data from the interferometer site at San Antonio is being done. A limited subset of the MSFC data acquired during Hurricane Alicia has been found to be valid. These were data which satisfied the phase linearity criteria. Approximately 2,000 location estimates have been produced on the valid data. The results of the DF analysis and the location data are being correlated with the McIDAS data base at Marshall Space Flight Center, and with the radar summary data provided by the Hurricane Research Division using the National weather Service radar Facility at Galveston, Texas.

  3. Interactive modeling of storm impact

    NASA Astrophysics Data System (ADS)

    van Rooijen, A.; Baart, F.; Roelvink, J. A.; Donchyts, G.; Scheel, F.; de Boer, W.

    2014-12-01

    In the past decades the impact of storms on the coastal zone has increasingly drawn the attention of policy makers and coastal planners, engineers and researchers. The mean reason for this interest is the high density of the world's population living near the ocean, in combination with climate change. Due to sea level rise and extremer weather conditions, many of the world's coastlines are becoming more vulnerable to the potential of flooding. Currently it is common practice to predict storm impact using physics-based numerical models. The numerical model utilizes several inputs (e.g. bathymetry, waves, surge) to calculate the impact on the coastline. Traditionally, the numerical modeller takes the following three steps: schematization/model setup, running and post-processing. This process generally has a total feedback time in the order of hours to days, and is suitable for so-called confirmatory modelling.However, often models are applied as an exploratory tool, in which the effect of e.g. different hydraulic conditions, or measures is investigated. The above described traditional work flow is not the most efficient method for exploratory modelling. Interactive modelling lets users adjust a simulation while running. For models typically used for storm impact studies (e.g. XBeach, Delft3D, D-Flow FM), the user can for instance change the storm surge level, wave conditions, or add a measure such as a nourishment or a seawall. The model will take the adjustments into account immediately, and will directly compute the effect. Using this method, tools can be developed in which stakeholders (e.g. coastal planners, policy makers) are in control and together evaluate ideas by interacting with the model. Here we will show initial results for interactive modelling with a storm impact model.

  4. Bifurcation theory and cardiac arrhythmias

    PubMed Central

    Karagueuzian, Hrayr S; Stepanyan, Hayk; Mandel, William J

    2013-01-01

    In this paper we review two types of dynamic behaviors defined by the bifurcation theory that are found to be particularly useful in describing two forms of cardiac electrical instabilities that are of considerable importance in cardiac arrhythmogenesis. The first is action potential duration (APD) alternans with an underlying dynamics consistent with the period doubling bifurcation theory. This form of electrical instability could lead to spatially discordant APD alternans leading to wavebreak and reentrant form of tachyarrhythmias. Factors that modulate the APD alternans are discussed. The second form of bifurcation of importance to cardiac arrhythmogenesis is the Hopf-homoclinic bifurcation that adequately describes the dynamics of the onset of early afterdepolarization (EAD)-mediated triggered activity (Hopf) that may cause ventricular tachycardia and ventricular fibrillation (VT/VF respectively). The self-termination of the triggered activity is compatible with the homoclinic bifurcation. Ionic and intracellular calcium dynamics underlying these dynamics are discussed using available experimental and simulation data. The dynamic analysis provides novel insights into the mechanisms of VT/VF, a major cause of sudden cardiac death in the US. PMID:23459417

  5. Problems with Modeling Plasmasphere Refilling After Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.

    2015-12-01

    During geomagnetic storms, the plasma in the outer plasmasphere is depleted as the plasma drifts away from the Earth across magnetic field (B) lines due to storm-time electric fields. After the storm, the plasmasphere refills due to an upward flow of plasma from the ionosphere that is initially supersonic (H+). The current numerical models of plasmasphere refilling are typically based on a numerical solution of the ion (H+, O+, He+) and electron continuity, momentum, and energy equations. The equations are solved along closed magnetic field lines that connect conjugate ionospheres, with allowance for cross-B plasma drift during storms. Both diffusion and hydrodynamic approximations have been adopted. The diffusion approximation neglects the nonlinear initial term in the momentum equations, so this approximation is not rigorously valid for early refilling times (~ day). At high altitudes, the plasma becomes collisionless and there are different temperatures parallel and perpendicular to B (not included in current models). Also, single-stream and multi-stream (separate ion streams from the conjugate ionospheres) formulations have been adopted, and the refilling features are different. These and other problems with the current plasmasphere refilling models will be discussed.

  6. Evolution of the ring current during two geomagnetic storms

    SciTech Connect

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-07-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  7. The Ring Current Response to Solar and Interplanetary Storm Drivers

    NASA Astrophysics Data System (ADS)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  8. Inducing Therapeutic Hypothermia in Cardiac Arrest Caused by Lightning Strike.

    PubMed

    Scantling, Dane; Frank, Brian; Pontell, Mathew E; Medinilla, Sandra

    2016-09-01

    Only limited clinical scenarios are grounds for induction of therapeutic hypothermia. Its use in traumatic cardiac arrests, including those from lightning strikes, is not well studied. Nonshockable cardiac arrest rhythms have only recently been included in resuscitation guidelines. We report a case of full neurological recovery with therapeutic hypothermia after a lightning-induced pulseless electrical activity cardiac arrest in an 18-year-old woman. We also review the important pathophysiology of lightning-induced cardiac arrest and neurologic sequelae, elaborate upon the mechanism of therapeutic hypothermia, and add case-based evidence in favor of the use of targeted temperature management in lightning-induced cardiac arrest.

  9. Uplift of Ionospheric Oxygen Ions During Extreme Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Huba, Joseph; Lakhina, Gurbax S.

    2013-01-01

    Research reported earlier in literature was conducted relating to estimation of the ionospheric electrical field, which may have occurred during the September 1859 Carrington geomagnetic storm event, with regard to modern-day consequences. In this research, the NRL SAMI2 ionospheric code has been modified and applied the estimated electric field to the dayside ionosphere. The modeling was done at 15-minute time increments to track the general ionospheric changes. Although it has been known that magnetospheric electric fields get down into the ionosphere, it has been only in the last ten years that scientists have discovered that intense magnetic storm electric fields do also. On the dayside, these dawn-to-dusk directed electric fields lift the plasma (electrons and ions) up to higher altitudes and latitudes. As plasma is removed from lower altitudes, solar UV creates new plasma, so the total plasma in the ionosphere is increased several-fold. Thus, this complex process creates super-dense plasmas at high altitudes (from 700 to 1,000 km and higher).

  10. Detection of flashing areas attributed to the frog cardiac function in the vagosympathetic trunk placed into a high frequency electric field.

    PubMed

    Pokrovskii, V M; Abushkevich, V G; Perova, Yu Yu; Perova, M Yu; Pokhotko, A G; Ardelyan, A N

    2016-05-01

    In a high frequency electric field, two flashing areas were observed during each contraction of the heart in the vagosympathetic trunk of a paralyzed frog with an intact brain. One area with a higher diameter was moving along the nerve from the heart at a speed of 16.6 ± 0.2 m/s. It was identified as afferent. Another area with a smaller diameter was spreading along the nerve towards the venous sinus of the frog heart at a speed of 5.6 ± 0.3 m/s, and it was efferent.

  11. Solar-Storm/Lunar Atmosphere Model (SSLAM): An Overview of the Effort and Description of the Driving Storm Environment

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Halekas, J. S.; Killen, R. M.; Delroy, G. T.; Gross, N.; Bleacher, V; Krauss-Varben, D.; Hurley, D; Zimmerman, M. I.

    2012-01-01

    On 29 April 1998, a coronal mass ejection (CME) was emitted from the Sun that had a significant impact on bodies located at 1 AU. The terrestrial magnetosphere did indeed become more electrically active during the storm passage but an obvious question is the effect of such a storm on an exposed rocky body like our Moon. The solar-storm/lunar atmosphere modeling effort (SSLAM) brings together surface interactions, exosphere, plasma, and surface charging models all run with a common driver - the solar storm and CME passage occurring from 1-4 May 1998. We present herein an expanded discussion on the solar driver during the 1-4 May 1998 period that included the passage of an intense coronal mass ejection (CME) that had> 10 times the solar wind density and had a compositional component of He++ that exceeded 20%. We also provide a very brief overview oflhe SSLAM system layout and overarching results. One primary result is that the CME driver plasma can greatly increase the exospheric content via sputtering, with total mass loss rates that approach 1 kg/s during the 2-day CME passage. By analogy, we suggest that CME-related sputtering increases might also be expected during a CME passage by a near-earth asteroid or at the Mars exobase, resulting in an enhanced loss of material.

  12. Computational approaches to understand cardiac electrophysiology and arrhythmias

    PubMed Central

    Roberts, Byron N.; Yang, Pei-Chi; Behrens, Steven B.; Moreno, Jonathan D.

    2012-01-01

    Cardiac rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. These impulses spread throughout the cardiac muscle to manifest as electrical waves in the whole heart. Regularity of electrical waves is critically important since they signal the heart muscle to contract, driving the primary function of the heart to act as a pump and deliver blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. For more than 50 years, mathematically based models of cardiac electrical activity have been used to improve understanding of basic mechanisms of normal and abnormal cardiac electrical function. Computer-based modeling approaches to understand cardiac activity are uniquely helpful because they allow for distillation of complex emergent behaviors into the key contributing components underlying them. Here we review the latest advances and novel concepts in the field as they relate to understanding the complex interplay between electrical, mechanical, structural, and genetic mechanisms during arrhythmia development at the level of ion channels, cells, and tissues. We also discuss the latest computational approaches to guiding arrhythmia therapy. PMID:22886409

  13. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

    Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst < or = -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.

  14. Dust storms - Great Plains, Africa, and Mars

    NASA Technical Reports Server (NTRS)

    Woiceshyn, P. M.; Krauss, R.; Minzner, R.; Shenk, W.

    1977-01-01

    Dust storms in the Great Plains of North America and in the Sahara Desert are analyzed on the basis of imagery from the geostationary Synchronous Meteorological Satellite. The onset time, location and areal extent of the dust storms are studied. Over land surfaces, contrast enhancement techniques are needed to obtain an adequate picture of dust storm development. In addition, infrared imagery may provide a means of monitoring the strong horizontal temperature gradients characteristic of dust cloud boundaries. Analogies between terrestrial dust storms and the airborne rivers of dust created by major Martian dust storms are also drawn.

  15. Storm Impacts on Potential Pathogens in Estuaries

    NASA Astrophysics Data System (ADS)

    Fries, J. Stephen; Noble, Rachel T.; Kelly, Ginger M.; Hsieh, Jennifer L.

    2007-02-01

    Estuarine and coastal environments are susceptible to a variety of changes driven by tropical storms and hurricanes. The 2005 Atlantic hurricane season impressed upon the public the devastating impacts of storms on coastal populations and the possible social and public health costs. Storm surges and subsequent flooding have the potential to redistribute water and associated contaminants, including a wide range of chemicals and microorganisms. While this impact is difficult to observe through monitoring during larger storms, smaller storms provide opportunities to observe the mechanisms responsible for contaminant and microbial transport.

  16. Space Derived Health Aids (Cardiac Pacemaker)

    NASA Technical Reports Server (NTRS)

    1981-01-01

    St. Jude Medical's Cardiac Rhythm Management Division's (formerly known as Pacesetter Systems, Inc.) pacer is a rechargeable cardiac pacemaker that eliminates the recurring need for surgery to implant a new battery. The Programalith is an advanced cardiac pacing system which permits a physician to reprogram a patient's implanted pacemaker without surgery. System consists of a pacemaker, together with a physician's console containing the programmer and a data printer. Signals are transmitted by wireless telemetry. Two-way communications, originating from spacecraft electrical power systems technology, allows physician to interrogate the pacemaker as to the status of the heart, then to fine tune the device to best suit the patient's needs.

  17. An intracloud lightning parameterization scheme for a storm electrification model

    NASA Technical Reports Server (NTRS)

    Helsdon, John H., Jr.; Wu, Gang; Farley, Richard D.

    1992-01-01

    The parameterization of an intracloud lightning discharge has been implemented in the present storm electrification model. The initiation, propagation direction, and termination of the discharge are computed using the magnitude and direction of the electric field vector as the determining criteria. The charge redistribution due to the lightning is approximated assuming the channel to be an isolated conductor with zero net charge over its entire length. Various simulations involving differing amounts of charge transferred and distribution of charges have been done. Values of charge transfer, dipole moment change, and electrical energy dissipation computed in the model are consistent with observations. The effects of the lightning-produced ions on the hydrometeor charges and electric field components depend strongly on the amount of charge transferred. A comparison between the measured electric field change of an actual intracloud flash and the field change due to the simulated discharge shows favorable agreement. Limitations of the parameterization scheme are discussed.

  18. Thyroid storm precipitated by duodenal ulcer perforation.

    PubMed

    Natsuda, Shoko; Nakashima, Yomi; Horie, Ichiro; Ando, Takao; Kawakami, Atsushi

    2015-01-01

    Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male) complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  19. [Diagnosis and treatment of thyroid storm].

    PubMed

    Akamizu, Takashi

    2012-11-01

    Thyrotoxic storm is a life-threatening condition requiring emergency treatment. Neither its epidemiological data nor diagnostic criteria have been fully established. We clarified the clinical and epidemiological characteristics of thyroid storm using nationwide surveys and then formulate diagnostic criteria for thyroid storm. To perform the nationwide survey on thyroid storm, we first developed tentative diagnostic criteria for thyroid storm, mainly based upon the literature (the first edition). We analyzed the relationship of the major features of thyroid storm to mortality and to certain other features. Finally, based upon the findings of these surveys, we revised the diagnostic criteria. Thyrotoxic storm is still a life-threatening disorder with over 10% mortality in Japan.

  20. Thermospheric storms and related ionospheric effects

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Spencer, N. W.

    1976-01-01

    A comparative study of thermospheric storms for equinox and winter conditions is presented based on neutral-composition measurements from the Aeros-A neutral-atmosphere temperature experiment. The main features of the two storms as inferred from changes in N2, Ar, He, and O are described, and their implications for current theories of thermospheric storms are discussed. On the basis of the study of the F-region critical frequency measured from a chain of ground-based ionospheric stations during the two storm periods, the general characteristics of the ionospheric storms and the traveling ionospheric disturbances are described. It is suggested that the positive and negative phases of ionospheric storms are different manifestations of thermospheric storms.

  1. Regional characteristics of dust storms in China

    NASA Astrophysics Data System (ADS)

    Qian, Weihong; Tang, Xu; Quan, Linsheng

    2004-09-01

    Regional characteristics of dust storms in northern China are analyzed using a rotated empirical orthogonal function (REOF), based on the annual days of dust storms from 1954 to 1998. The relationships between regional dust storms corresponding to other factors such as precipitation and temperature are explored. The results show that five leading modes of dust storms exist in the following areas: the Taklamakan Desert (Tarim Basin) over the Xinjiang region (far northwestern China), the eastern part of Inner Mongolia (North China), the Tsaidam Basin, the Tibetan Plateau, and the upper reaches of the Yellow River (Gobi Desert). These areas are associated with an arid climate and frequent winds. For the first mode in the Tarim Basin, most dust storms appear in the 1980s, while dust storms become less frequent in the 1990s. The second mode (North China) shows the highest frequency of dust storms in the mid-1960s but the frequency decreases afterward. The third mode indicates a decreasing trend of annual dust storms after the mid-1960s but with a high interannual variability. The fourth mode also shows a decreasing trend but with a low interannual variability. The fifth mode displays a high frequency of dust storms in the 1970s followed by a decreasing trend. For the five modes of dust storm distribution, four of the centers are located in desert regions. The annual dust storms of a selected station in each mode region are shown to compare the coefficient time series of these modes. The negative correlation between the prior winter temperature and dust storm frequency is identified for most stations. There is no consistency in the correlation between the dust storm frequency and the annual rainfall as well as the prior winter rainfall at these stations. The activity of dust storms in northern China are directly linked to the cyclone activity, especially for the interdecadal variability.

  2. Agents to reduce cytokine storm

    PubMed Central

    Gerlach, Herwig

    2016-01-01

    The increasing insight into pathomechanisms of dysregulated host response in several inflammatory diseases led to the implementation of the term “cytokine storm” in the literature more than 20 years ago. Direct toxic effects as well as indirect immunomodulatory mechanisms during cytokine storm have been described and were the basis for the rationale to use several substances and devices in life-threatening infections and hyperinflammatory states. Clinical trials have been performed, most of them in the form of minor, investigator-initiated protocols; major clinical trials focused mostly on sepsis and septic shock. The following review tries to summarize the background, pathophysiology, and results of clinical investigations that had implications for the development of therapeutic strategies and international guidelines for the management of hyperinflammation during syndromes of cytokine storm in adult patients, predominantly in septic shock. PMID:28105327

  3. Storm Warnings on Lake Balaton,

    DTIC Science & Technology

    1982-04-06

    Vorhergesagt1 _ ___ !, ( SSZ . LI). (331, K _. )___ : 2 !daenkmmuflg 3 ja 4__ ’%ein %ZtLron S-0 6 j. a 3 10 24 126 B 88% A N in 4 13 173 186 B, 60% SZu...15 24 15 14 13 14 13 12 16 7 7 4 5 5 % 12 12 7 It 7 7 S 7 6 6 7 3 3 2 2 2 Key: 1-duration 2-number of storms 3-hours and one-third of storms last only...16-18 August 1959 and on 11- 13 June 1958, with a duration of 49.9 hours. Table 4 provides information about the frequency distribution of the maximum

  4. Dust storm off Western Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The impacts of Saharan dust storms reach far beyond Africa. Wind-swept deserts spill airborne dust particles out over the Atlantic Ocean where they can enter trade winds bound for Central and North America and the Caribbean. This Moderate Resolution Imaging Spectroradiometer (MODIS) image shows a dust storm casting an opaque cloud of cloud across the Canary Islands and the Atlantic Ocean west of Africa on June 30, 2002. In general it takes between 5 and 7 days for such an event to cross the Atlantic. The dust has been shown to introduce foreign bacteria and fungi that have damaged reef ecosystems and have even been hypothesized as a cause of increasing occurrences of respiratory complaints in places like Florida, where the amount of Saharan dust reaching the state has been increasing over the past 25 years.

  5. Severe storms observing satellite study

    NASA Technical Reports Server (NTRS)

    Iwens, R. P.; Stern, D. A.

    1976-01-01

    Payload distribution and the attitude control system for the multi-mission modular spacecraft/StormSat configuration are discussed. The design of the advanced atmospheric sounder and imaging radiometer (AASIR) gimbal drive and its servomechanism is described. Onboard data handling, data downlink communications, and ground data handling systems are developed. Additional topics covered include: magnetic unloading at synchronous altitude, north-south stationkeeping, and the feasibility and impact of flying the microwave atmospheric sounding radiometer (MASR) as an additional payload.

  6. Magnetosphere-associated storms and the autonomous storms in the ionosphere-plasmasphere environment

    NASA Astrophysics Data System (ADS)

    Gulyaeva, T. L.; Stanislawska, I.

    2010-01-01

    Global GPS-derived ionosphere maps (GIM) of total electron content (TEC) were transformed into magnetic latitude (MLAT) versus magnetic local time (MLT) frame. TEC enhancement or depletion marked by W index show dominant electron content depressions and the ionosphere-plasmasphere storms increasing by nighttime, at high magnetic latitudes and over the crests of equatorial anomaly. Based on W maps, the planetary Wp index was produced and used for derivation of a catalogue of more than 140 TEC storms during 1999-2009. In total 33 space weather intense storms and 35 moderate storms are revealed with four series of indices (AE, Ap, Dst and Wp) but more than half Wp storms were either partially overlapping in time with magnetic storm or observed autonomously under non-storm magnetosphere conditions. Relation between an annual number of intense Dst storms and Wp storms has been used for their prediction towards the peak of the forthcoming 24th solar cycle.

  7. Investigation of Ionospheric Response to Geomagnetic Storms over a Low Latitude Station, Ile-Ife, Nigeria

    NASA Astrophysics Data System (ADS)

    Jimoh, Oluwaseyi E.; Yesufu, Thomas K.; Ariyibi, Emmanuel A.

    2016-06-01

    Due to several complexities associated with the equatorial ionosphere, and the significant role which the total electron content (TEC) variability plays in GPS signal transmission, there is the need to monitor irregularities in TEC during storm events. The GPS SCINDA receiver data at Ile-Ife, Nigeria, was analysed with a view to characterizing the ionospheric response to geomagnetic storms on 9 March and 1 October 2012. Presently, positive storm effects, peaks in TEC which were associated with prompt penetration of electric fields and changes in neutral gas composition were observed for the storms. The maximum percentage deviation in TEC of about 120 and 45% were observed for 9 March and 1 October 2012, respectively. An obvious negative percentage TEC deviation subsequent to sudden storm commencement (SSC) was observed and besides a geomagnetic storm does not necessarily suggest a high scintillation intensity (S4) index. The present results show that magnetic storm events at low latitude regions may have an adverse effect on navigation and communication systems.

  8. Storm-related carbon monoxide poisoning: lessons learned from recent epidemics.

    PubMed

    Hampson, N B; Stock, A L

    2006-01-01

    Over the past 15 years, a number of epidemics of carbon monoxide (CO) poisoning related to various storms have been reported. While the geographical location of these outbreaks and the types of storms involved has been diverse, review of the events reveals a number of common factors and themes. This paper summarizes the details of 9 published reports describing CO poisoning associated with 11 different storms. When common patterns were examined, five "lessons to be learned" from the experience were derived. They are (1) loss of electrical power can lead indirectly to carbon monoxide poisoning, (2) campaigns to educate the public about risks for CO exposure should be timed regionally to coincide with the peak risk for typical storms, (3) significant opportunities exist for prevention of generator-related CO poisoning, (4) there is a window of time for effective communications regarding the dangers of CO poisoning even after a storm strikes, and (5) the major sources of CO responsible for poisonings can be related to the type of storm and are predictable. It is hoped that each of these lessons are used to develop public programs designed to prevent storm-associated CO poisoning in the future.

  9. Simulation and 'TWINS Observations of the 22 July 2009 Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Buzulukova, Natalia Y.; Chen, Sheng-Hsien; Valek, Phil; Goldstein, Jerry; McComas, David

    2010-01-01

    TWINS is the first mission to perform stereo imaging of the Earth's ring current. The magnetic storm on 22 July 2009 is the largest storm observed since TWINS began routine stereo imaging in June 2008. On 22 July 2009, the Dst dropped to nearly -80nT at 7:00 and 10:00 UT. During the main phase and at the peak of the storm, TWINS 1 and 2 were near apogee and moving from pre-dawn to post-dawn local time. The energetic neutral atom (ENA) imagers on the 2 spacecraft captured the storm intensification and the formation of the partial ring current. The peak of the ENA emissions was seen in the midnight-to-dawn local-time sector. The development of this storm has been simulated using the Comprehensive Ring Current Model (CRCM) to understand and interpret the observed signatures. We perform CRCM runs with constant and time-varying magnetic field. The model calculations are validated by comparing the simulated ENA and ion flux intensities with TWINS ENA images and in-situ ion data from THEMIS satellites. Simulation with static magnetic field produces a strong shielding electric field that skews the ion drift trajectories toward dawn. The model's corresponding peak ENA emissions are always eastward than those in the observed TWINS images. On the other hand, simulation with a dynamic magnetic field gives better spatial agreements with both ENA and insitu particle data, suggesting that temporal variations of the geomagnetic field exert a significant influence upon global ring current ion dynamics.

  10. Simulation and Twins Observations of the 22 July 2009 Storm

    NASA Technical Reports Server (NTRS)

    Fok, M.-C.; Buzulukova, N.; Chen, S.-H.; Valek, P. W.; Goldstein, J.; McComas, D. J.

    2011-01-01

    TWINS is the first mission to perform stereo imaging of the Earth's ring current. The magnetic storm on 22 July 2009 was at the time the largest storm observed since TWINS began routine stereo imaging in June 2008. On 22 July 2009, the Dst dropped to nearly .80 nT at 0700 and 1000 UT. During the main phase, and at the peak of the storm, TWINS 1 and 2 were near apogee and moving between predawn and postdawn local time. The energetic neutral atom (ENA) imagers on the two spacecraft captured the storm intensification and the formation of the partial ring current. The peak of the high-altitude ENA emissions was seen in the midnight-to-dawn local time sector. The development of this storm has been simulated using the comprehensive ring current model (CRCM) to understand and interpret the observed signatures. We perform CRCM runs with constant and time-varying magnetic field. The model calculations are validated by comparing the simulated ENA and ion flux intensities with TWINS ENA images and in situ ion data from a THEMIS satellite. Simulation with a static magnetic field produces a strong shielding electric field that skews the ion drift trajectories toward dawn. The model's corresponding peak ENA emissions are always more eastward than those in the observed TWINS images. On the other hand, the simulation with a dynamic magnetic field gives better spatial agreement with both ENA and in situ particle data, suggesting that temporal variations of the geomagnetic field exert a significant influence upon global ring current ion dynamics.

  11. Dust Storm Time Lapse Shows Opportunity's Skies Darken

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Dust Storm Time Lapse Shows Opportunity's Skies Darken

    NASA's Opportunity rover is literally seeing some of its darkest days. Both Mars Exploration Rovers have been riding out a regional dust storm for several weeks. Conditions became particularly dreary in the Meridiani Planum region where Opportunity sits, perched on the edge of 'Victoria Crater.'

    This image is a time-lapse composite where each horizon-survey image has been compressed horizontally (but not vertically) to emphasize the sky. The relative brightness and darkness of the sky from sol to sol (over a 30-sol period beginning June 14, 2007) is depicted accurately in these images, which view roughly the same part of the plains southwest of the rover. The images are approximately true color composites, generated from calibrated radiance data files using the panoramic camera's 601-nanometer, 535-nanometer and 482-nanometer filters.

    The rovers' atmospheric science team is concerned that smaller, regional dust storms could expand into a larger, globe-encircling storm. That could extend the time the sun stays obscured, challenging the capability of Opportunity's solar panels to produce enough electricity for the rover to function.

    Fortunately, as of July 19, 2007, the Opportunity site is clearing slightly. When the storm ends, atmospheric scientists hope to review data from the rovers that will help them determine what sort of dust was being lifted and distributed.

    The numbers across the top of the image report a measurement of atmospheric opacity, called by the Greek letter tau. The lower the number, the clearer the sky. Both Opportunity and Spirit have been recording higher tau measurements in July 2007 than they had seen any time previously in their three and a half years on Mars. The five sol numbers across the bottom correspond (left to right) to June 14, June 30, July 5, July 13 and July 15, 2007.

  12. Responses in the polar and equatorial ionosphere to the March 2015 St. Patrick Day storm

    NASA Astrophysics Data System (ADS)

    Hairston, Marc; Coley, W. R.; Stoneback, Russell

    2016-11-01

    The St. Patrick Day storm of 2015 (17 March 2015) occurred at a unique time when there were multiple spacecraft observing the Earth's ionosphere between 350 and 885 km. Observations of the plasma flows and densities from the five operational polar-orbiting DMSP spacecraft combined with those from the equatorial-orbiting C/NOFS spacecraft provided a comprehensive global record of the both the polar and equatorial ionosphere regions' responses to the storm. This paper presents an overview of the data from this suite of spacecraft focusing on the following aspects: (1) the polar cap ionosphere's reaction to the storm, (2) the change in the penetration electric field in the midlatitude region as a function of time and the solar local time during the storm, (3) the equatorial ionosphere's response of the meridional (vertical) flows to the penetration electric field and the disturbance dynamo during the storm, and (4) the creation of a predawn ionospheric bubble system near the equator during the storm's main phase that was observed at low altitudes by C/NOFS and later at high altitudes by several DMSP. Examining these phenomenon enable us to trace the dynamic flow of energy from the solar wind input in the polar ionosphere all the way to the equatorial ionosphere.

  13. Dust Storm in Southern California

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Along historic Route 66, just southeast of the little town of Amboy, California, lies a dried-up lake. Dry lakebeds are good sources of two things: salt and dust. In this image, the now-parched Bristol Lake offers up both. On April 12, 2007, dust storms menaced the area around Amboy. To the northwest, near Newberry Springs, California, dust hampered visibility and led to a multi-car collision on Interstate 40, killing two people and injuring several others. The same day, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of a dust storm in the dry remains of Bristol Lake. Many small dust clouds boil up from the ground surface, casting their shadows to the northwest. A bright white cloud floating over the dust also throws its shadow onto the ground below. East of the dust storm are salt works that stand out from the surrounding landscape thanks to their straight lines and sharp angles. Dark ground surfaces alternate with mined white salt in a network of stripes. When lakes evaporate, chemicals that had been dissolved in the water stay behind, making dry lake beds an ideal place to find heavy concentrations of minerals, including salt. Besides the salt works, something else appears in stark contrast to this arid place. Lush green fields of irrigated crops appear in the east. Besides their color, their orderly arrangement reveals their human-made origin.

  14. The relationship of storm severity to directionally resolved radio emissions

    NASA Technical Reports Server (NTRS)

    Johnson, R. O.; Bushman, M. L.; Sherrill, W. M.

    1980-01-01

    Directionally resolved atmospheric radio frequency emission data were acquired from thunderstorms occurring in the central and southwestern United States. In addition, RF sferic tracking data were obtained from hurricanes and tropical depressions occurring in the Gulf of Mexico. The data were acquired using a crossed baseline phase interferometer operating at a frequency of 2.001 MHz. The received atmospherics were tested for phase linearity across the array, and azimuth/elevation angles of arrival were computed in real time. A histogram analysis of sferic burst count versus azimuth provided lines of bearing to centers of intense electrical activity. Analysis indicates a consistent capability of the phase linear direction finder to detect severe meteorological activity to distances of 2000 km from the receiving site. The technique evidences the ability to discriminate severe storms from nonsevere storms coexistent in large regional scale thunderstorm activity.

  15. The responses of the thermosphere due to a geomagnetic storm: A MHD model

    NASA Technical Reports Server (NTRS)

    Wu, S. T.; Chang, S.

    1972-01-01

    A magnetohydrodynamics theory was used to study the dynamic response of the neutral atmosphere to a geomagnetic storm. A full set of magnetohydrodynamic equations appropriate for the present problem is derived and their various orders of approximation are discussed in some detail. In order to demonstrate the usefulness of this theoretical model, the May 1967 geomagnetic storm data were used in the resulting set of nonlinear, time dependent, partial differential magnetohydrodynamic equations to calculate variations of the thermosphere due to the storm. The numerical results are presented for wind speeds, electric field strength, and amount of joule heating at a constant altitude for the data recorded. Data show that the strongest thermospheric responses are at the polar region becoming weaker in the equatorial region. This may lead to the speculation that a thermospheric wave is generated in the polar region due to the geomagnetic storm which propagates towards the equator.

  16. Extreme Lightning Flash Rates as an Early Indicator of Severe Storms

    NASA Technical Reports Server (NTRS)

    Goodman, Steven J.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Extreme lightning flash rates are proving to be an early indicator of intensifying storms capable of producing tornadoes, damaging winds and hail. Most of this lightning is in the cloud, where the naked eye can not see it. Recent global observations of thunderstorms from space indicate that giant electrical storms (supercells and convective complexes) with flash rates on the order of 1 flash per second are most common over the land masses of the America sub-tropics and equatorial Congo Basin. Within the United States, the average tornado warning lead time on a national basis is about 11 min. The real-time observation of extreme flash rates and the rapid increase in the in-cloud flash rate, signalling the intensification of the storm updraft, may provide as much as a 50% increase in severe storm warning lead time.

  17. Electric Utility Industry Experience with Geomagnetic Disturbances

    DTIC Science & Technology

    1991-09-01

    the March 13, 1989, geomagnetic storm. Source: North American Electric Reliability Council ................................................ 9 Fig. 2.2...Events and K intensity recorded in North America during the March 13, 1989, geomagnetic storm. Source: North American Electric Reliability Council. 2.2...Unit I experienced VAR excursions of 150 to 200 MVAR. Additional VARs were consumed by the saturated step-up transformers. An empirical equation

  18. Toward microendoscopy-inspired cardiac optogenetics in vivo: technical overview and perspective.

    PubMed

    Klimas, Aleksandra; Entcheva, Emilia

    2014-08-01

    The ability to perform precise, spatially localized actuation and measurements of electrical activity in the heart is crucial in understanding cardiac electrophysiology and devising new therapeutic solutions for control of cardiac arrhythmias. Current cardiac imaging techniques (i.e. optical mapping) employ voltage- or calcium-sensitive fluorescent dyes to visualize the electrical signal propagation through cardiac syncytium in vitro or in situ with very high-spatiotemporal resolution. The extension of optogenetics into the cardiac field, where cardiac tissue is genetically altered to express light-sensitive ion channels allowing electrical activity to be elicited or suppressed in a precise cell-specific way, has opened the possibility for all-optical interrogation of cardiac electrophysiology. In vivo application of cardiac optogenetics faces multiple challenges and necessitates suitable optical systems employing fiber optics to actuate and sense electrical signals. In this technical perspective, we present a compendium of clinically relevant access routes to different parts of the cardiac electrical conduction system based on currently employed catheter imaging systems and determine the quantitative size constraints for endoscopic cardiac optogenetics. We discuss the relevant technical advancements in microendoscopy, cardiac imaging, and optogenetics and outline the strategies for combining them to create a portable, miniaturized fiber-based system for all-optical interrogation of cardiac electrophysiology in vivo.

  19. Toward microendoscopy-inspired cardiac optogenetics in vivo: technical overview and perspective

    PubMed Central

    Klimas, Aleksandra; Entcheva, Emilia

    2014-01-01

    Abstract. The ability to perform precise, spatially localized actuation and measurements of electrical activity in the heart is crucial in understanding cardiac electrophysiology and devising new therapeutic solutions for control of cardiac arrhythmias. Current cardiac imaging techniques (i.e. optical mapping) employ voltage- or calcium-sensitive fluorescent dyes to visualize the electrical signal propagation through cardiac syncytium in vitro or in situ with very high-spatiotemporal resolution. The extension of optogenetics into the cardiac field, where cardiac tissue is genetically altered to express light-sensitive ion channels allowing electrical activity to be elicited or suppressed in a precise cell-specific way, has opened the possibility for all-optical interrogation of cardiac electrophysiology. In vivo application of cardiac optogenetics faces multiple challenges and necessitates suitable optical systems employing fiber optics to actuate and sense electrical signals. In this technical perspective, we present a compendium of clinically relevant access routes to different parts of the cardiac electrical conduction system based on currently employed catheter imaging systems and determine the quantitative size constraints for endoscopic cardiac optogenetics. We discuss the relevant technical advancements in microendoscopy, cardiac imaging, and optogenetics and outline the strategies for combining them to create a portable, miniaturized fiber-based system for all-optical interrogation of cardiac electrophysiology in vivo. PMID:25117076

  20. Cardiac xenotransplantation.

    PubMed

    DiSesa, V J

    1997-12-01

    Heart failure is an important medical and public health problem. Although medical therapy is effective for many people, the only definitive therapy is heart transplantation, which is limited severely by the number of donors. Mechanical devices presently are used as "bridges" to transplantation. Their widespread use may solve the donor shortage problem, but at present, mechanical devices are limited by problems related to blood clotting, power supply, and foreign body infection. Cardiac xenotransplantation using animal donors is a potential biologic solution to the donor organ shortage. The immune response, consisting of hyperacute rejection, acute vascular rejection, and cellular rejection, currently prevents clinical xenotransplantation. Advances in the solution of these problems have been made using conventional immunosuppressive drugs and newer agents whose use is based on an understanding of important steps in xenoimmunity. The most exciting approaches use tools of molecular biology to create genetically engineered donors and to induce states of donor and recipient bone marrow chimerism and tolerance in xenogeneic organ recipients. The successful future strategy may use a combination of a genetically engineered donor and a chimeric recipient with or without nonspecific immunosuppressive drugs.

  1. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. ); Taylor, E.R. Jr. ); Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  2. Electric Utility Industry Experience with Geomagnetic Disturbances

    SciTech Connect

    Barnes, P.R.

    1991-01-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration.

  3. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W.; Taylor, E.R. Jr.; Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems` responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  4. The danger to satellites from meteor storms

    NASA Astrophysics Data System (ADS)

    Beech, M.; Brown, P.; Jones, J.; Webster, A. R.

    During past meteor storms impact probabilities of between 1 and 0.01 percent have be realized per 50m^2 of exposed surface area at altitudes corresponding to both GEO and LEO. The most likely meteoroid stream to yield a storm in the near future is that of the Leonids. Numerical simulations of the orbital evolution of hypothetical Leonid stream meteoroids suggest that storms may occur in the years 1999 and 2000.

  5. Cardiac alternans and intracellular calcium cycling

    PubMed Central

    Edwards, Joshua N.; Blatter, Lothar A.

    2014-01-01

    Cardiac alternans refers to a condition in which there is a periodic beat-to-beat oscillation in electrical activity and the strength of cardiac muscle contraction at a constant heart rate. Clinically, cardiac alternans occurs in settings that are typical for cardiac arrhythmias and has been causally linked to these conditions. At the cellular level, alternans is defined as beat-to-beat alternations in contraction amplitude (mechanical alternans), action potential duration (APD; electrical or APD alternans), and Ca2+ transient amplitude (Ca2+ alternans). The cause of alternans is multifactorial, however alternans always originate from disturbances of the bi-directional coupling between membrane voltage (Vm) and intracellular calcium ([Ca2+]i). Bi-directional coupling refers to the fact that in cardiac cells, Vm depolarization and the generation of action potentials cause the elevation of [Ca2+]i that is required for contraction (a process referred to as excitation-contraction coupling), the changes of [Ca2+]i on the other hand control Vm because important membrane currents are Ca2+-dependent. Evidence is mounting that alternans is ultimately caused by disturbances of cellular Ca2+ signaling. Here we review how two key factors of cardiac cellular Ca2+ cycling - the release of Ca2+ from internal stores and the capability of clearing the cytosol from Ca2+ after each beat - determine the conditions under which alternans occurs. The contributions from key Ca2+ handling proteins - surface membrane channels, ion pumps and transporters, and internal Ca2+ release channels - are discussed. PMID:25040398

  6. Storm-induced changes of the topside ionosphere as deduced from incoherent-scatter radars. Master's thesis

    SciTech Connect

    Lunn, K.J.

    1990-01-01

    Incoherent scatter radar observations from Millstone Hill, Saint Santin, and Arecibo are used to illustrate changes of the topside ionosphere during a geomagnetic storm. These observations consist of electron density, electron and ion temperatures, and ion velocity components parallel and perpendicular to the magnetic field. These parameters can further describe changes in ion composition, electric fields, and neutral winds. Attention is given to a specific storm during the Equinox Transition Study (ETS) of September 1984. In order to isolate the storm effects in the topside ionosphere, a comparison will be made between a disturbed and quiet day. A novel result from this study is the finding of correlated oscillations between parallel and perpendicular ion velocity components which are apparently storm induced. Previously, these oscillations have been observed primarily at night, but now it's noticed that during storm conditions there are prominent oscillations during the day.

  7. Sudden cardiac death risk stratification.

    PubMed

    Deyell, Marc W; Krahn, Andrew D; Goldberger, Jeffrey J

    2015-06-05

    Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

  8. Numerical Simulations of 1990 Saturn's Giant Storm

    NASA Astrophysics Data System (ADS)

    Garcia-Melendo, E.; Sanchez-Lavega, A.

    2015-12-01

    We present here a study of the Saturn's 1990 equatorial major storm based on numerical simulations. Six planetary scale storms, nicknamed as Great White Spots (GWS) have been observed since the nineteenth century, three of them at the equatorial region in 1876 (~ +8º), 1933 (~ +2º), and 1990 (+12º), on the broad prograde equatorial jet where equatorial dynamics dominated producing a storm nucleus, with rapid expansion to the east and west to become a planetary-scale disturbance (Sánchez-Lavega, CHAOS 4, 341-353, 1994). We have detailed information, ground-based CCD imaging and Hubble Space Telescope (HST) data, for the 1990 event. Numerical experiments on the 1990 storm indicate that the onset of the storm can only be reproduced if the Voyager era background zonal flow is used, which suggests that it dominated the circulation dynamics at the storm's outbreak region at that time. We review the possible impact of the 1990 storm on the equatorial jet, storm dynamics, and how it relates to the observed storm morphology and zonal wind measurements derived from HST observations (Barnet et al., Icarus 100, 499-511, 1992). Observations also describe the formation of equatorial planetary waves and instabilities during the disturbance. We discuss the impact of major energy and mass injection by a planetary-scale convective event on the equatorial dynamics following our simulation results.

  9. Observing storm surges from satellite altimetry

    NASA Astrophysics Data System (ADS)

    Han, Guoqi

    2016-07-01

    Storm surges can cause catastrophic damage to properties and loss of life in coastal communities. Thus it is important to enhance our capabilities of observing and forecasting storm surges for mitigating damage and loss. In this presentation we show examples of observing storm surges around the world using nadir satellite altimetry, during Hurricane Sandy, Igor, and Isaac, as well as other cyclone events. The satellite observations are evaluated against tide-gauge observations and discussed for dynamic mechanisms. We also show the potential of a new wide-swath altimetry mission, the Surface Water and Ocean Topography (SWOT), for observing storm surges.

  10. A Personal Storm Warning Service

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Although lightning detection systems operated by government agencies, utilities and other businesses provide storm warnings, this information often does not reach the public until some time after the observations have been made. A low-cost personal lightning detector offers a significant safety advantage to private flyers, boaters, golfers and others. Developed by Airborne Research Associates, the detectors originated in Space Shuttle tests of an optical lightning detection technique. The commercial device is pointed toward a cloud to detect invisible intracloud lightning by sensing subtle changes in light presence. The majority of the sales have been to golf courses. Additional products and more advanced applications are in progress.

  11. Complex Dynamics Along One Dimensional Cardiac Fibers

    NASA Astrophysics Data System (ADS)

    Fox, Jeff; Stubna, Mike; Hua, Fei; Bodenschatz, Eberhard; Gilmour, Robert

    2001-03-01

    Beat-to-beat alternation of cardiac electrical properties (electrical alternans; EA) may destabilize spiral waves in cardiac tissue, leading to cardiac arrhythmias. Recent studies have suggested that propagation of EA may not be uniform, resulting in concordant (in phase) and discordant (out of phase) EA across spatially distributed systems. In this study we induced EA in canine cardiac Purkinje fibers by pacing at short cycle lengths (CL). At CL between 110-150 ms, discordant EA occurred distal to the site of stimulation, whereas at CL less than 110 ms, complex dynamics (period 4 and higher) appeared. The mechanism for this behavior was studied using a model of a cardiac fiber in which local dynamics were determined by action potential duration (APD) and conduction velocity restitution curves. We investigated the stability of spatially extended EA and observed discordant EA. We also showed that models in which the APD restitution curve has a local minimum exhibited complex activation patterns. The dispersion of electrical properties caused by such patterns may facilitate reentrant excitation.

  12. 11th International Conference on Atmospheric Electricity

    NASA Technical Reports Server (NTRS)

    Christian, H. J. (Compiler)

    1999-01-01

    This document contains the proceedings from the 11th International Conference on Atmospheric Electricity (ICAE 99), held June 7-11, 1999. This conference was attended by scientists and researchers from around the world. The subjects covered included natural and artificially initiated lightning, lightning in the middle and upper atmosphere (sprites and jets), lightning protection and safety, lightning detection techniques (ground, airborne, and space-based), storm physics, electric fields near and within thunderstorms, storm electrification, atmospheric ions and chemistry, shumann resonances, satellite observations of lightning, global electrical processes, fair weather electricity, and instrumentation.

  13. Aconitine "challenge" test reveals a single whole-body exposure to diesel exhaust increases cardiac arrhythmia risk in hypertensive rats

    EPA Science Inventory

    Epidemiological studies demonstrate a significant association between cardiac electrical dysfunction, arrhythmias and air pollution exposure. Sensitivity to aconitine-induced arrhythmia has been used repeatedly to examine the factors that increase the risk of such cardiac electri...

  14. In the Eye of the Storm: A Participatory Course on Coastal Storms

    ERIC Educational Resources Information Center

    Curtis, Scott

    2013-01-01

    Storm disasters are amplified in the coastal environment due to population pressures and the power of the sea. The upper-division/graduate university course "Coastal Storms" was designed to equip future practitioners with the skills necessary to understand, respond to, and mitigate for these natural disasters. To accomplish this, "Coastal Storms"…

  15. Prediction of Solar Storms in Future

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Using the Solar Vector Magnetograph, a solar observation facility at NASA's Marshall Space Flight Center (MSFC), scientists from the National Space Science and Technology Center (NSSTC) in Huntsville, Alabama, are monitoring the explosive potential of magnetic areas of the Sun. This effort could someday lead to better prediction of severe space weather, a phenomenon that occurs when blasts of particles and magnetic fields from the Sun impact the magnetosphere, the magnetic bubble around the Earth. When massive solar explosions, known as coronal mass ejections, blast through the Sun's outer atmosphere and plow toward Earth at speeds of thousands of miles per second, the resulting effects can be harmful to communication satellites and astronauts outside the Earth's magnetosphere. Like severe weather on Earth, severe space weather can be costly. On the ground, the magnetic storm wrought by these solar particles can knock out electric power. The researchers from MSFC and NSSTC's solar physics group develop instruments for measuring magnetic fields on the Sun. With these instruments, the group studies the origin, structure, and evolution of the solar magnetic field and the impact it has on Earth's space environment. This photograph shows the Solar Vector Magnetograph and Dr. Mona Hagyard of MSFC, the director of the observatory who leads the development, operation and research program of the Solar Vector Magnetograph.

  16. Prediction of Solar Storms in Future

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Using the Solar Vector Magnetograph, a solar observation facility at NASA's Marshall Space Flight Center (MSFC), scientists from the National Space Science and Technology Center (NSSTC) in Huntsville, Alabama, are monitoring the explosive potential of magnetic areas of the Sun. This effort could someday lead to better prediction of severe space weather, a phenomenon that occurs when blasts of particles and magnetic fields from the Sun impact the magnetosphere, the magnetic bubble around the Earth. When massive solar explosions, known as coronal mass ejections, blast through the Sun's outer atmosphere and plow toward Earth at speeds of thousands of miles per second, the resulting effects can be harmful to communication satellites and astronauts outside the Earth's magnetosphere. Like severe weather on Earth, severe space weather can be costly. On the ground, magnetic storms wrought by these solar particles can knock out electric power. Photographed are a group of contributing researchers in front of the Solar Vector Magnetograph at MSFC. The researchers are part of NSSTC's solar physics group, which develops instruments for measuring magnetic fields on the Sun. With these instruments, the group studies the origin, structure, and evolution of the solar magnetic fields and the impact they have on Earth's space environment.

  17. Prediction of Solar Storms in Future

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Marshall Space Flight Center (MSFC) and university scientists from the National Space Science and Technology Center (NSSTC) in Huntsville, Alabama, are watching the Sun in an effort to better predict space weather - blasts of particles and magnetic fields from the Sun that impact the magnetosphere, the magnetic bubble around the Earth. Filled by charged particles trapped in the Earth's magnetic field, the spherical comet-shaped magnetosphere extends out 40,000 miles from Earth's surface in the sunward direction and more in other directions. This image illustrates the Sun-Earth cornection. When massive solar explosions, known as coronal mass ejections, blast through the Sun's outer atmosphere and plow toward Earth at speeds of thousands of miles per second, the resulting effects can be harmful to communication satellites and astronauts outside the Earth's magnetosphere. Like severe weather on Earth, severe space weather can be costly. On the ground, magnetic storms wrought by these solar particles can knock out electric power. By using the Solar Vector Magnetograph, a solar observation facility at MSFC, scientists are learning what signs to look for as indicators of potential severe space weather.

  18. Severe Local Storms Cultural Heritage

    NASA Astrophysics Data System (ADS)

    Gladich, I.; Gallai, I.; Giaiotti, D. B.; Morgan, G. M.; Stel, F.

    2009-09-01

    Local storms always had a deep impact on people communities, mainly because of the severe damage caused, because of their unpredictability and, up to a few years ago, even because of the lack of knowledge and awareness on their physical origin. Because of this large impact on real life and on imagination, people needed and wanted to describe and report the occurrence of these events, giving them suited names. Often, these nouns are related to the myth developed to explain the cause of the events. In this work, a short presentation and description of the popular nouns used to describe severe local storm events in different areas of the World is given. Countries taken into account span from Italy, moving toward Africa and reaching a few communities of Native Americans. The etymology of the names gives interesting information, useful even under the anthropological point of view, on the Culture and Believes of the peoples who adopted them. This research work is the result of an underground activity carried out in the last ten years by the authors, during their contacts with students and researchers coming from different Countries and mainly met at the International Center for Theoretical Physics in Trieste.

  19. Ionospheric response to great geomagnetic storms during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

    The analyses of ionospheric responses due to great geomagnetic storms i.e. Dst index < 350 nT that occurred during solar cycle 23 are presented. The GPS Total Electron Content (TEC) and ionosonde data over Southern and Northern Hemisphere mid-latitudes were used to study the ionospheric responses. A geomagnetic latitude region of ±30° to ±46° within a longitude sector of 15° to 40° was considered. Using a criteria of Dst < -350 nT, there were only four great storm periods (29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004) in solar cycle 23. Analysis has shown that ionospheric dynamics during these disturbed conditions could be due to a number of dynamic and electrodynamics processes in both Hemispheres. In some instances the ionosphere responds differently to the same storm condition in both Hemispheres. Physical mechanisms related to (but not limited to) composition changes and electric fields will be discussed.

  20. Origin of Cardiac Fibroblasts and the Role of Periostin

    PubMed Central

    Snider, Paige; Standley, Kara N.; Wang, Jian; Azhar, Mohamad; Doetschman, Thomas; Conway, Simon J.

    2009-01-01

    Cardiac fibroblasts are the most populous non-myocyte cell type within the mature heart and are required for extracellular matrix synthesis and deposition, generation of the cardiac skeleton, and to electrically insulate the atria from the ventricles. Significantly, cardiac fibroblasts have also been shown to play an important role in cardiomyocyte growth and expansion of the ventricular chambers during heart development. Although there are currently no cardiac fibroblast-restricted molecular markers, it is generally envisaged that the majority of the cardiac fibroblasts are derived from the proepicardium via epithelial-to-mesenchymal transformation. However, still relatively little is known about when and where the cardiac fibroblasts cells are generated, the lineage of each cell, and how cardiac fibroblasts move to reside in their final position throughout all four cardiac chambers. In this review we summarize the current understanding regarding the function of Periostin, a useful marker of the non-cardiomyocyte lineages, and its role during cardiac morphogenesis. Characterization of the cardiac fibroblast lineage and identification of the signals that maintain, expand and regulate their differentiation will be required to improve our understanding of cardiac function in both normal and pathophysiological states. PMID:19893021

  1. Tropical Storm Ernesto over Cuba

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Microwave Image

    These infrared, microwave, and visible images were created with data retrieved by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite.

    Infrared Image Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

    Microwave Image In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

    Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue. Therefore deep blue areas in storms show where the most

  2. Cardiac tamponade (image)

    MedlinePlus

    Cardiac tamponade is a condition involving compression of the heart caused by blood or fluid accumulation in the space ... they cannot adequately fill or pump blood. Cardiac tamponade is an emergency condition that requires hospitalization.

  3. Sudden Cardiac Arrest

    MedlinePlus

    ... from American Heart Association Aneurysms and Dissections Angina Arrhythmia Bundle Branch Block Cardiomyopathy Carotid Artery Disease Chronic ... terms: SCA, sudden cardiac death (SCD), sudden death, arrhythmias, ... ventricular fibrillation, defibrillator, automatic cardiac defibrillator ( ...

  4. What Is Cardiac Rehabilitation?

    MedlinePlus

    ANSWERS by heart Treatments + Tests What Is Cardiac Rehabilitation? A cardiac rehabilitation (rehab) program takes place in a hospital or ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ...

  5. Cardiac arrest: resuscitation and reperfusion.

    PubMed

    Patil, Kaustubha D; Halperin, Henry R; Becker, Lance B

    2015-06-05

    The modern treatment of cardiac arrest is an increasingly complex medical procedure with a rapidly changing array of therapeutic approaches designed to restore life to victims of sudden death. The 2 primary goals of providing artificial circulation and defibrillation to halt ventricular fibrillation remain of paramount importance for saving lives. They have undergone significant improvements in technology and dissemination into the community subsequent to their establishment 60 years ago. The evolution of artificial circulation includes efforts to optimize manual cardiopulmonary resuscitation, external mechanical cardiopulmonary resuscitation devices designed to augment circulation, and may soon advance further into the rapid deployment of specially designed internal emergency cardiopulmonary bypass devices. The development of defibrillation technologies has progressed from bulky internal defibrillators paddles applied directly to the heart, to manually controlled external defibrillators, to automatic external defibrillators that can now be obtained over-the-counter for widespread use in the community or home. But the modern treatment of cardiac arrest now involves more than merely providing circulation and defibrillation. As suggested by a 3-phase model of treatment, newer approaches targeting patients who have had a more prolonged cardiac arrest include treatment of the metabolic phase of cardiac arrest with therapeutic hypothermia, agents to treat or prevent reperfusion injury, new strategies specifically focused on pulseless electric activity, which is the presenting rhythm in at least one third of cardiac arrests, and aggressive post resuscitation care. There are discoveries at the cellular and molecular level about ischemia and reperfusion pathobiology that may be translated into future new therapies. On the near horizon is the combination of advanced cardiopulmonary bypass plus a cocktail of multiple agents targeted at restoration of normal metabolism and

  6. Arecibo observations of ionospheric perturbations associated with the passage of Tropical Storm Odette

    NASA Astrophysics Data System (ADS)

    Bishop, R. L.; Aponte, N.; Earle, G. D.; Sulzer, M.; Larsen, M. F.; Peng, G. S.

    2006-11-01

    A suite of instruments including incoherent scatter radar, ionosonde, and a satellite-bourne GPS receiver observed the ionosphere immediately following the passage of a tropical storm. Tropical Storm Odette formed on 4 December 2003 and proceeded northeasterly over the next 4 days, passing within 600 km of the Arecibo Observatory (AO). On the night of 7-8 December AO measured F region plasma densities and velocities nearly coincident with the storm. Large velocity variations, 10-80 m/s, are evident in the plasma drift components. The variations appear wave-like with an average period of 90 min at 367 km. Zonal drifts were observed with magnitudes significantly greater than commonly observed for similar geomagnetic conditions. The Ramey ionosonde observed intense midlatitude spread F on the night following the closest passage of the storm. GPS occultations within the storm path showed an increase in gravity wave activity and F region scintillation. Combining the local increase in gravity wave activity with the large drift variations and dominant meridional electric field observed immediately following the storm's traversal of the flux tube coincident with the AO observing volume provide insight into coupling between mesoscale weather systems and the ionosphere.

  7. Storm-time ionization enhancements at the topside low-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Dmitriev, A.; Yeh, H.-C.

    2008-05-01

    Ion density enhancements at the topside low-latitude ionosphere during a Bastille storm on 15-16 July 2000 and Halloween storms on 29-31 October 2003 were studied using data from ROCSAT-1/IPEI experiment. Prominent ion density enhancements demonstrate similar temporal dynamics both in the sunlit and in the nightside hemispheres. The ion density increases dramatically (up to two orders of magnitude) during the main phase of the geomagnetic storms and reaches peak values at the storm maximum. The density enhancements are mostly localized in the region of a South Atlantic Anomaly (SAA), which is characterized by very intense fluxes of energetic particles. The dynamics of near-Earth radiation was studied using SAMPEX/LEICA data on >0.6 MeV electrons and >0.8 MeV protons at around 600 km altitude. During the magnetic storms the energetic particle fluxes in the SAA region and in its vicinity increase more than three orders of magnitude. The location of increased fluxes overlaps well with the regions of ion density enhancements. Two mechanisms were considered to be responsible for the generation of storm-time ion density enhancements: prompt penetration of the interplanetary electric field and abundant ionization of the ionosphere by enhanced precipitation of energetic particles from the radiation belt.

  8. Engineered hybrid cardiac patches with multifunctional electronics for online monitoring and regulation of tissue function

    NASA Astrophysics Data System (ADS)

    Feiner, Ron; Engel, Leeya; Fleischer, Sharon; Malki, Maayan; Gal, Idan; Shapira, Assaf; Shacham-Diamand, Yosi; Dvir, Tal

    2016-06-01

    In cardiac tissue engineering approaches to treat myocardial infarction, cardiac cells are seeded within three-dimensional porous scaffolds to create functional cardiac patches. However, current cardiac patches do not allow for online monitoring and reporting of engineered-tissue performance, and do not interfere to deliver signals for patch activation or to enable its integration with the host. Here, we report an engineered cardiac patch that integrates cardiac cells with flexible, freestanding electronics and a 3D nanocomposite scaffold. The patch exhibited robust electronic properties, enabling the recording of cellular electrical activities and the on-demand provision of electrical stimulation for synchronizing cell contraction. We also show that electroactive polymers containing biological factors can be deposited on designated electrodes to release drugs in the patch microenvironment on demand. We expect that the integration of complex electronics within cardiac patches will eventually provide therapeutic control and regulation of cardiac function.

  9. Engineered hybrid cardiac patches with multifunctional electronics for online monitoring and regulation of tissue function

    PubMed Central

    Feiner, Ron; Engel, Leeya; Fleischer, Sharon; Malki, Maayan; Gal, Idan; Shapira, Assaf; Shacham-Diamand, Yosi; Dvir, Tal

    2016-01-01

    In cardiac tissue engineering approaches to treat myocardial infarction, cardiac cells are seeded within three-dimensional porous scaffolds to create functional cardiac patches. However, current cardiac patches do not allow for online monitoring and reporting of engineered-tissue performance, and do not interfere to deliver signals for patch activation or to enable its integration with the host. Here, we report an engineered cardiac patch that integrates cardiac cells with flexible, free-standing electronics and a 3D nanocomposite scaffold. The patch exhibited robust electronic properties, enabling the recording of cellular electrical activities and the on-demand provision of electrical stimulation for synchronizing cell contraction. We also show that electroactive polymers containing biological factors can be deposited on designated electrodes to release drugs in the patch microenvironment on-demand. We expect that the integration of complex electronics within cardiac patches will eventually provide therapeutic control and regulation of cardiac function. PMID:26974408

  10. NASA's 3-D Animation of Tropical Storm Ulika from Space

    NASA Video Gallery

    An animated 3-D flyby of Tropical Storm Ulika using GPM's Radar data showed some strong convective storms inside the tropical storm were dropping precipitation at a rate of over 187 mm (7.4 inches)...

  11. Severe storms and local weather research

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Developments in the use of space related techniques to understand storms and local weather are summarized. The observation of lightning, storm development, cloud development, mesoscale phenomena, and ageostrophic circulation are discussed. Data acquisition, analysis, and the development of improved sensor and computer systems capability are described. Signal processing and analysis and application of Doppler lidar data are discussed. Progress in numerous experiments is summarized.

  12. Polarimetric radar characteristics of storms with and without lightning activity

    NASA Astrophysics Data System (ADS)

    Mattos, Enrique V.; Machado, Luiz A. T.; Williams, Earle R.; Albrecht, Rachel I.

    2016-12-01

    This paper analyzes the cloud microphysics in different layers of storms as a function of three-dimensional total lightning density. A mobile X-band polarimetric radar and very high frequency (VHF) sources from Lightning Mapping Array (LMA) observations during the 2011/2012 Brazil spring-summer were used to determine the microphysical signatures of radar vertical profiles and lightning density. This study quantified the behavior of 5.3 million vertical profiles of the horizontal reflectivity (ZH), differential reflectivity (ZDR), specific differential phase (KDP), and correlation coefficient (ρHV). The principal changes in the polarimetric variables occurred only for VHF source rate density greater than 14 VHF sources per km2 in 4 min. These storms showed an enhanced positive KDP in the mixed 1 layer (from 0 to -15°C) probably associated with supercooled liquid water signatures, whereas regions with negative ZDR and KDP and moderate ZH in the mixed 2 layer (from -15 to -40°C) were possibly associated with the presence of conical graupel. The glaciated (above -40°C) and upper part of the mixed 2 layers showed a significant trend to negative KDP with an increase in lightning density, in agreement with vertical alignment of ice particle by the cloud electric field. A conceptual model that presents the microphysical signatures in storms with and without lightning activity was constructed. The observations documented in this study provide an understanding of how the combinations of polarimetric variables could help to identify storms with different lightning density and vice versa.

  13. Position of the Ring Current Peak During ICME- and CIR-Driven Storms

    NASA Astrophysics Data System (ADS)

    Jahn, J.; Elliott, H. A.; Perez, J. D.; Pulkkinen, T. I.; Samara, M.; Barrows, S.

    2006-12-01

    Under appropriate solar wind driving during the main phase of a storm, the peak of the ring current (as deduced from ENA observations) can move past midnight towards early morning magnetic local times. Several mechanisms explaining this dawnward shift have been proposed, including the deformation of the convection electric field due to the shielding electric field, and the local time dependence of the plasma sheet density. We present a study of all Dst storms during the IMAGE mission (2000-2005) for which below 80 keV hydrogen ENA remote sensing ring current data are available. We expand previous investigations in several areas. In addition to all ICME-driven events we also include all CIR-driven storms. The relevant (and sufficient) solar wind driving may occur in either event type. We discuss the coupling between solar wind and magnetosphere in more detail, also considering the magnetospheric state prior to storm main phase. This will better represent the role of the plasma sheet in the control of the storm time ring current peak position. Furthermore, we include a comparison of ENA-based results with ground-based magnetometer observations of the ring current morphology for a select number of cases. This provides ground truth for studies previously based on remote- sensing ENA observations alone.

  14. Middle- and low-latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Nava, B.; Rodríguez-Zuluaga, J.; Alazo-Cuartas, K.; Kashcheyev, A.; Migoya-Orué, Y.; Radicella, S. M.; Amory-Mazaudier, C.; Fleury, R.

    2016-04-01

    This paper presents a study of the St Patrick's Day storm of 2015, with its ionospheric response at middle and low latitudes. The effects of the storm in each longitudinal sector (Asian, African, American, and Pacific) are characterized using global and regional electron content. At the beginning of the storm, one or two ionospheric positive storm effects are observed depending on the longitudinal zones. After the main phase of the storm, a strong decrease in ionization is observed at all longitudes, lasting several days. The American region exhibits the most remarkable increase in vertical total electron content (vTEC), while in the Asian sector, the largest decrease in vTEC is observed. At low latitudes, using spectral analysis, we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field (PPEF) and of the disturbance dynamo electric field (DDEF) on the basis of ground magnetic data. Concerning the PPEF, Earth's magnetic field oscillations occur simultaneously in the Asian, African, and American sectors, during southward magnetization of the Bz component of the interplanetary magnetic field. Concerning the DDEF, diurnal magnetic oscillations in the horizontal component H of the Earth's magnetic field exhibit a behavior that is opposed to the regular one. These diurnal oscillations are recognized to last several days in all longitudinal sectors. The observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models.

  15. Interactions Between Convective Storms and Their Environment

    NASA Technical Reports Server (NTRS)

    Maddox, R. A.; Hoxit, L. R.; Chappell, C. F.

    1979-01-01

    The ways in which intense convective storms interact with their environment are considered for a number of specific severe storm situations. A physical model of subcloud wind fields and vertical wind profiles was developed to explain the often observed intensification of convective storms that move along or across thermal boundaries. A number of special, unusually dense, data sets were used to substantiate features of the model. GOES imagery was used in conjunction with objectively analyzed surface wind data to develop a nowcast technique that might be used to identify specific storm cells likely to become tornadic. It was shown that circulations associated with organized meso-alpha and meso-beta scale storm complexes may, on occasion, strongly modify tropospheric thermodynamic patterns and flow fields.

  16. A rare case of thyroid storm.

    PubMed

    McMillen, Brock; Dhillon, Manvinder Shelley; Yong-Yow, Sabrina

    2016-04-18

    Thyroid storm is a rare and life-threatening state of thyroid hormone excess. Rapid recognition of thyroid storm is key to decreasing the morbidity and mortality of this condition. Clinical manifestations of thyroid storm include unexplained weight loss, hyperactivity and irritability. The most common causes of thyrotoxicosis are Graves' disease, toxic multinodular goitre and toxic adenoma. We present a rare case of thyroid storm induced by dual nivolumab and ipilimumab immunotherapy in a patient receiving treatment for advanced melanoma. In this case, our patient was admitted for thyroid storm 1 month after initiating treatment with nivolumab and ipilimumab immunotherapy. The patient was treated with β-blockers, antithyroid medications and systemic steroids resulting in an improvement in thyroid function testing and symptoms.

  17. Ionospheric effects at low latitudes during the March 22, 1979, geomagnetic storm

    SciTech Connect

    Fesen, C.G. ); Crowley, G.; Roble, R.G. )

    1989-05-01

    This paper investigates the response of the equatorial ionosphere to the neutral atmosphere perturbations produced by the magnetic storm of March 22, 1979. A numerical model of the equatorial ionosphere is used to calculate the maximum electron densities and F layer heights associated with a storm-perturbed neutral atmosphere and circulation model. Possible electric field perturbations due to the storm are ignored. The neutral atmosphere and dynamics are simulated by the National Center for Atmospheric Research thermospheric general circulation model (TGCM) for the storm day of March 22, 1979, and the preceding quiet day. The most striking feature of the TGCM storm day simulations is the presence of waves in the neutral composition, wind, and temperature fields which propagate from high latitudes to the equator. The TGCM-calculated fields for the two days are input into a low-latitude ionosphere model which calculates n{sub max} and h{sub max} between {plus minus}20{degree}dip latitude. The calculated nighttime 6300-{angstrom} airglow emission and the altitude profiles of electron concentration are also highly perturbed by the storm. Examination of ionosonde data for March 22, 1979, shows remarkable agreement between the measured and predicted changes in f{sub 0}F{sub 2} and h{sub max} near 140{degree}W. Poorer agreement near 70{degree}W may be due to the neglect of electric field perturbations and the approximations inherent in the modeling. The results of these simulations indicate that the major factor influencing the storm time ionospheric behavior in this case is the neutral wind.

  18. Cardiac ion channels

    PubMed Central

    Priest, Birgit T; McDermott, Jeff S

    2015-01-01

    Ion channels are critical for all aspects of cardiac function, including rhythmicity and contractility. Consequently, ion channels are key targets for therapeutics aimed at cardiac pathophysiologies such as atrial fibrillation or angina. At the same time, off-target interactions of drugs with cardiac ion channels can be the cause of unwanted side effects. This manuscript aims to review the physiology and pharmacology of key cardiac ion channels. The intent is to highlight recent developments for therapeutic development, as well as elucidate potential mechanisms for drug-induced cardiac side effects, rather than present an in-depth review of each channel subtype. PMID:26556552

  19. Ionospheric storm effects and equatorial plasma irregularities during the 17-18 March 2015 event

    NASA Astrophysics Data System (ADS)

    Zhou, Yun-Liang; Lühr, Hermann; Xiong, Chao; Pfaff, Robert F.

    2016-09-01

    The intense magnetic storm on 17-18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm-related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (Em). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/prenoon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the postsunset sector. As a response to a short-lived decline of Em, EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 h. Only after the onset of recovery phase does EPI activity start again in the postmidnight sector, lasting more than 7 h. This comprehensive view of

  20. Controlled Cardiac Computed Tomography

    PubMed Central

    Wang, Chenglin; Liu, Ying; Wang, Ge

    2006-01-01

    Cardiac computed tomography (CT) has been a hot topic for years because of the clinical importance of cardiac diseases and the rapid evolution of CT systems. In this paper, we propose a novel strategy for controlled cardiac CT that may effectively reduce image artifacts due to cardiac and respiratory motions. Our approach is radically different from existing ones and is based on controlling the X-ray source rotation velocity and powering status in reference to the cardiac motion. We theoretically show that by such a control-based intervention the data acquisition process can be optimized for cardiac CT in the cases of periodic and quasiperiodic cardiac motions. Specifically, we formulate the corresponding coordination/control schemes for either exact or approximate matches between the ideal and actual source positions, and report representative simulation results that support our analytic findings. PMID:23165017

  1. An Evaluation of Lightning Flash Rate Parameterizations Based on Observations of Colorado Storms during DC3

    NASA Astrophysics Data System (ADS)

    Basarab, B.; Fuchs, B.; Rutledge, S. A.

    2013-12-01

    Predicting lightning activity in thunderstorms is important in order to accurately quantify the production of nitrogen oxides (NOx = NO + NO2) by lightning (LNOx). Lightning is an important global source of NOx, and since NOx is a chemical precursor to ozone, the climatological impacts of LNOx could be significant. Many cloud-resolving models rely on parameterizations to predict lightning and LNOx since the processes leading to charge separation and lightning discharge are not yet fully understood. This study evaluates predicted flash rates based on existing lightning parameterizations against flash rates observed for Colorado storms during the Deep Convective Clouds and Chemistry Experiment (DC3). Evaluating lightning parameterizations against storm observations is a useful way to possibly improve the prediction of flash rates and LNOx in models. Additionally, since convective storms that form in the eastern plains of Colorado can be different thermodynamically and electrically from storms in other regions, it is useful to test existing parameterizations against observations from these storms. We present an analysis of the dynamics, microphysics, and lightning characteristics of two case studies, severe storms that developed on 6 and 7 June 2012. This analysis includes dual-Doppler derived horizontal and vertical velocities, a hydrometeor identification based on polarimetric radar variables using the CSU-CHILL radar, and insight into the charge structure using observations from the northern Colorado Lightning Mapping Array (LMA). Flash rates were inferred from the LMA data using a flash counting algorithm. We have calculated various microphysical and dynamical parameters for these storms that have been used in empirical flash rate parameterizations. In particular, maximum vertical velocity has been used to predict flash rates in some cloud-resolving chemistry simulations. We diagnose flash rates for the 6 and 7 June storms using this parameterization and compare

  2. An electrified dust storm over the Negev desert, Israel

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Price, C. G.; Yaniv, R.; Katz, S.

    2015-12-01

    We report on atmospheric electrical measurements conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30035'N, 34045'E) during a massive dust storm that occurred over the Eastern Mediterranean region on 10-11 February 2015. The event transported Saharan dust from Egypt and the Sinai Peninsula in advance of the warm front of a Cyprus low pressure system. Satellite images show the dust plume covering the Negev desert and Southern Israel and moving north. The concentrations of PM10 particles measured by the air-quality monitoring network of the Israeli Ministry of the Environment in Beer-Sheba reached values > 450 μg m-3 and AOT from the AERONET station in Sde-Boker was 1.5 on the 10th. The gradual intensification of the event reached peak values on February 11th of over 1200 μg m-3 and AOT of 1.8. This was the most severe dust event in a decade. Continuous measurements of the fair weather vertical electric field (Ez) and vertical current density (Jz) were conducted with 1 minute temporal resolution. Meteorological data was also recorded at the site. As the dust was advected over the observation site, we noted very large fluctuations in the electrical parameters. Since the onset of the dust storm, the Ez values changed between +1000 and +8000 V m-1 while the Jz fluctuated between -10 pA m2 and +20 pA m2, both on time-scales of a few minutes. These values are a significant departures from the mean fair-weather values measured at the site, which are -~200 V m-1 and ~2 pA m2. The disturbed episodes lasted for several hours on the 10th and 11th and coincided with local meteorological conditions related to the wind direction, which carried large amounts of dust particles. We interpret the rapid changes as caused by the transport of electrically charged dust. Calculation of the total electrical charge during the dust storm will be presented.

  3. Numerical Simulations of the Ring Current During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Chen, M. W.; Lemon, C.; Guild, T. B.; Schulz, M.; Roeder, J. L.; Lui, A.; Keesee, A. M.; Goldstein, J.; Le, G.; Rodriguez, J. V.

    2012-12-01

    Recent progress in ring current modeling has shown the importance of a self-consistent treatment of particle transport along with magnetic and electric fields in the inner magnetosphere. The ring current intensity and spatial distribution are significantly affected by variations in the plasma sheet (the major source to the ring current), the cross polar cap potential, and compressions and expansions of the magnetosphere. We simulate the ion and electron ring current and plasma sheet by using the magnetically and electrically self-consistent Rice Convection Model-Equilibrium [Lemon et al., JGR, 2004] with a time-varying magnetopause driven by upstream solar wind and interplanetary magnetic (IMF) conditions and with time-varying plasma sheet distributions as boundary conditions. Examples of detailed comparisons of simulated storm events with in-situ magnetic intensities (e. g., GOES, Polar/MPA, or THEMIS) and proton flux spectra (e. g., LANL/MPA and SOPA, Polar/CAMMICE, or THEMIS) and energetic neutral atom (ENA) fluxes (e. g., TWINS) will be shown. We will also present comparisons of observed electron flux spectra with simulations based on a few simple electron loss models. These data-model comparisons test the ability of our model to characterize the ring current environment and the storm-time inner magnetospheric magnetic field.

  4. A new parameter of geomagnetic storms for the severity of space weather

    NASA Astrophysics Data System (ADS)

    Balan, N.; Batista, I. S.; Tulasi Ram, S.; Rajesh, P. K.

    2016-12-01

    Using the continuous Dst data available since 1957 and H component data for the Carrington space weather event of 1859, the paper shows that the mean value of Dst during the main phase of geomagnetic storms, called mean DstMP, is a unique parameter that can indicate the severity of space weather. All storms having high mean DstMP (≤-250 nT), which corresponds to high amount of energy input in the magnetosphere-ionosphere system in short duration, are found associated with severe space weather events that caused all known electric power outages and telegraph system failures.

  5. Probability of occurrence of planetary ionosphere storms associated with the magnetosphere disturbance storm time events

    NASA Astrophysics Data System (ADS)

    Gulyaeva, T. L.; Arikan, F.; Stanislawska, I.

    2014-11-01

    The ionospheric W index allows to distinguish state of the ionosphere and plasmasphere from quiet conditions (W = 0 or ±1) to intense storm (W = ±4) ranging the plasma density enhancements (positive phase) or plasma density depletions (negative phase) regarding the quiet ionosphere. The global W index maps are produced for a period 1999-2014 from Global Ionospheric Maps of Total Electron Content, GIM-TEC, designed by Jet Propulson Laboratory, converted from geographic frame (-87.5:2.5:87.5° in latitude, -180:5:180° in longitude) to geomagnetic frame (-85:5:85° in magnetic latitude, -180:5:180° in magnetic longitude). The probability of occurrence of planetary ionosphere storm during the magnetic disturbance storm time, Dst, event is evaluated with the superposed epoch analysis for 77 intense storms (Dst ≤ -100 nT) and 230 moderate storms (-100 < Dst ≤ -50 nT) with start time, t0, defined at Dst storm main phase onset. It is found that the intensity of negative storm, iW-, exceeds the intensity of positive storm, iW+, by 1.5-2 times. An empirical formula of iW+ and iW- in terms of peak Dst is deduced exhibiting an opposite trends of relation of intensity of ionosphere-plasmasphere storm with regard to intensity of Dst storm.

  6. Storm Sudden Commencements Without Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Park, Wooyeon; Lee, Jeongwoo; Yi, Yu; Ssessanga, Nicholas; Oh, Suyeon

    2015-09-01

    Storm sudden commencements (SSCs) occur due to a rapid compression of the Earth's magnetic field. This is generally believed to be caused by interplanetary (IP) shocks, but with exceptions. In this paper we explore possible causes of SSCs other than IP shocks through a statistical study of geomagnetic storms using SYM-H data provided by the World Data Center for Geomagnetism ? Kyoto and by applying a superposed epoch analysis to simultaneous solar wind parameters obtained with the Advanced Composition Explorer (ACE) satellite. We select a total of 274 geomagnetic storms with minimum SYM-H of less than ?30nT during 1998-2008 and regard them as SSCs if SYM-H increases by more than 10 nT over 10 minutes. Under this criterion, we found 103 geomagnetic storms with both SSC and IP shocks and 28 storms with SSC not associated with IP shocks. Storms in the former group share the property that the strength of the interplanetary magnetic field (IMF), proton density and proton velocity increase together with SYM-H, implying the action of IP shocks. During the storms in the latter group, only the proton density rises with SYM-H. We find that the density increase is associated with either high speed streams (HSSs) or interplanetary coronal mass ejections (ICMEs), and suggest that HSSs and ICMEs may be alternative contributors to SSCs.

  7. long duration dust storm sequences on Mars

    NASA Astrophysics Data System (ADS)

    Wang, H.

    2012-12-01

    The Mars Global Surveyor (MGS) Mars Observer Camera (MOC) and Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI) Mars daily global maps have revealed new characteristics for long duration dust storm sequences. These dust storm sequences have long histories of more than a week, travel long distances out of their origination region, and influence large areas in different regions of the planet. During the Ls = 180 - 360 season, except for global dust storms which involve multiple remote dust lifting centers and generally expand explosively from the southern hemisphere northward, other long-lived dust storm sequences usually travel southward through the Acidalia-Chryse, Utopia-Isidis or Arcadia-Amazonis channels with subsequent dust lifting along the way. Sometimes, they penetrate remarkably deep to the southern high latitudes, producing fantastic display of dust band. During the rest of the year, long duration dust storm sequences usually originate from the Argyre/Solis, Hellas/Noachis, or Cimmeria/Sirenum area and travel northward toward the southern low latitudes. Each route exhibits its own peculiar characteristics. We will present our results about these long duration dust storm sequences summarized from the complete archive of MGS MOC daily global maps and two years of MRO MARCI daily global maps. The systematic daily nearly global coverage of these maps makes it feasible to reconstruct the history of long duration dust storm sequences with detail.

  8. In Brief: Cassini images Saturn storm

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-11-01

    The Cassini spacecraft has spotted an 8000-kilometer-wide, hurricane-like storm around Saturn's South Pole, NASA announced on 9 November. The storm has a dark `eye' at the South Pole along with eye-wall clouds and spiral arms, but it is not known if moist convection-the driver of hurricanes on Earth-drives the Saturn storm. A movie taken by Cassini's camera indicates that the winds are blowing clockwise at about 560 kilometers per hour. Although large storms have been observed on other planets in the past-most notably, Jupiter's Great Red Spot-this is the first storm found to have eye-wall clouds and a relatively calm center. Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena, said the storm looks like a hurricane but is not behaving like one. ``Whatever it is, we are going to focus on the eye of this storm and find out why it is there.''

  9. Stability of subsea pipelines during large storms

    PubMed Central

    Draper, Scott; An, Hongwei; Cheng, Liang; White, David J.; Griffiths, Terry

    2015-01-01

    On-bottom stability design of subsea pipelines transporting hydrocarbons is important to ensure safety and reliability but is challenging to achieve in the onerous metocean (meteorological and oceanographic) conditions typical of large storms (such as tropical cyclones, hurricanes or typhoons). This challenge is increased by the fact that industry design guidelines presently give no guidance on how to incorporate the potential benefits of seabed mobility, which can lead to lowering and self-burial of the pipeline on a sandy seabed. In this paper, we demonstrate recent advances in experimental modelling of pipeline scour and present results investigating how pipeline stability can change in a large storm. An emphasis is placed on the initial development of the storm, where scour is inevitable on an erodible bed as the storm velocities build up to peak conditions. During this initial development, we compare the rate at which peak near-bed velocities increase in a large storm (typically less than 10−3 m s−2) to the rate at which a pipeline scours and subsequently lowers (which is dependent not only on the storm velocities, but also on the mechanism of lowering and the pipeline properties). We show that the relative magnitude of these rates influences pipeline embedment during a storm and the stability of the pipeline. PMID:25512592

  10. A pharmacologic review of cardiac arrest.

    PubMed

    Wagner, Bradley J; Yunker, Nancy S

    2014-01-01

    Cardiac arrest is manifested by arrhythmias (ventricular fibrillation or pulseless ventricular tachycardia, pulseless electrical activity, or asystole) resulting in minimal to no forward blood flow to the body's oxygen-dependent tissues. Defibrillation and cardiopulmonary resuscitation (CPR) should be initiated immediately as they have been shown to increase return of spontaneous circulation and survival to discharge rates. Cardiac arrest in the surgical patient population has devastating consequences. Data specific to the surgical patient found that 1 in 203 surgical patients experienced cardiac arrest requiring CPR within 30 days after surgery. A subgroup analysis found that 1 in 1,020 plastic surgery patients required CPR in this same time frame. Thirty-day mortality in the general surgery patient population was 72%. The American Heart Association updates the advanced cardiac life support (ACLS) guidelines every 5 years. Their latest publication in 2010 recommended that the resuscitative protocol be transitioned from its basic life support sequence of airway-breathing-chest compressions to chest compressions-airway-breathing. All health care professionals should have an understanding of the clinical presentation and medical management of cardiac arrest. Maintaining biannual basic life support and ACLS certification ensures that health care professionals remain current with American Heart Association guideline recommendations. Guideline-directed management of cardiac arrest should include timely implementation of the ACLS algorithm to maximize patient outcomes.

  11. Biomimetic materials design for cardiac tissue regeneration.

    PubMed

    Dunn, David A; Hodge, Alexander J; Lipke, Elizabeth A

    2014-01-01

    Cardiovascular disease is the leading cause of death worldwide. In the absence of sufficient numbers of organs for heart transplant, alternate approaches for healing or replacing diseased heart tissue are under investigation. Designing biomimetic materials to support these approaches will be essential to their overall success. Strategies for cardiac tissue engineering include injection of cells, implantation of three-dimensional tissue constructs or patches, injection of acellular materials, and replacement of valves. To replicate physiological function and facilitate engraftment into native tissue, materials used in these approaches should have properties that mimic those of the natural cardiac environment. Multiple aspects of the cardiac microenvironment have been emulated using biomimetic materials including delivery of bioactive factors, presentation of cell-specific adhesion sites, design of surface topography to guide tissue alignment and dictate cell shape, modulation of mechanical stiffness and electrical conductivity, and fabrication of three-dimensional structures to guide tissue formation and function. Biomaterials can be engineered to assist in stem cell expansion and differentiation, to protect cells during injection and facilitate their retention and survival in vivo, and to provide mechanical support and guidance for engineered tissue formation. Numerous studies have investigated the use of biomimetic materials for cardiac regeneration. Biomimetic material design will continue to exploit advances in nanotechnology to better recreate the cellular environment and advance cardiac regeneration. Overall, biomimetic materials are moving the field of cardiac regenerative medicine forward and promise to deliver new therapies in combating heart disease.

  12. Statistical analysis of storm-time near-Earth current systems

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Katus, R. M.; Ilie, R.

    2015-08-01

    Currents from the Hot Electron and Ion Drift Integrator (HEIDI) inner magnetospheric model results for all of the 90 intense storms (disturbance storm-time (Dst) minimum < -100 nT) from solar cycle 23 (1996-2005) are calculated, presented, and analyzed. We have categorized these currents into the various systems that exist in near-Earth space, specifically the eastward and westward symmetric ring current, the partial ring current, the banana current, and the tail current. The current results from each run set are combined by a normalized superposed epoch analysis technique that scales the timeline of each phase of each storm before summing the results. It is found that there is a systematic ordering to the current systems, with the asymmetric current systems peaking during storm main phase (tail current rising first, then the banana current, followed by the partial ring current) and the symmetric current systems peaking during the early recovery phase (westward and eastward symmetric ring current having simultaneous maxima). The median and mean peak amplitudes for the current systems ranged from 1 to 3 MA, depending on the setup configuration used in HEIDI, except for the eastward symmetric ring current, for which the mean never exceeded 0.3 MA for any HEIDI setup. The self-consistent electric field description in HEIDI yielded larger tail and banana currents than the Volland-Stern electric field, while the partial and symmetric ring currents had similar peak values between the two applied electric field models.

  13. Reduced Baroclinicity During Martian Global Dust Storms

    NASA Astrophysics Data System (ADS)

    Battalio, Joseph; Szunyogh, Istvan; Lemmon, Mark

    2015-11-01

    The eddy kinetic energy equation is applied to the Mars Analysis Correction Data Assimilation (MACDA) dataset during the pre-winter solstice period for the northern hemisphere of Mars. Traveling waves are triggered by geopotential flux convergence, grow baroclinically, and decay barotropically. Higher optical depth increases the static stability, which reduces vertical and meridional heat fluxes. Traveling waves during a global dust storm year develop a mixed baroclinic/barotropic growth phase before decaying barotropically. Baroclinic energy conversion is reduced during the global dust storm, but eddy intensity is undiminished. Instead, the frequency of storms is reduced due to a stabilized vertical profile.

  14. Desert Shield and Desert Storm Emerging Observations

    DTIC Science & Technology

    1991-10-07

    becomes much more apparent over relatively flat terrain. d. Recommended or Ongoing Action. The M577 CPV is scheduled to yo through a system conversion to...STORM Vehicle exchange policy at maintenanfce points. 9? 40115 4f996 (0017?) DESERT STORM Fretracide, peor ommunication. poor flank ceerdihutien. 24...02413 fll% yo (00M) DEIil SIONM Distribut ion of Wcom arM Iaf amon units 4??44 INAI8 (002 n) TILSll STORM Pro-combat trainfig V4 14145 U’,411 (00276

  15. Measured winter performance of storm windows

    SciTech Connect

    Klems, Joseph H.

    2002-08-23

    Direct comparison measurements were made between various prime/storm window combinations and a well-weatherstripped, single-hung replacement window with a low-E selective glazing. Measurements were made using an accurate outdoor calorimetric facility with the windows facing north. The doublehung prime window was made intentionally leaky. Nevertheless, heat flows due to air infiltration were found to be small, and performance of the prime/storm combinations was approximately what would be expected from calculations that neglect air infiltration. Prime/low-E storm window combinations performed very similarly to the replacement window. Interestingly, solar heat gain was not negligible, even in north-facing orientation.

  16. TEC Variations Over Korean Peninsula During Magnetic Storm

    NASA Astrophysics Data System (ADS)

    Ji, E.-Y.; Choi, B.-K.; Kim, K.-H.; Lee, D.-H.; Cho, J.-H.; Chung, J.-K.; Park, J.-U.

    2008-03-01

    By analyzing the observations from a number of ground- and space-based instruments, including ionosonde, magnetometers, and ACE interplanetary data, we examine the response of the ionospheric TEC over Korea during 2003 magnetic storms. We found that the variation of vertical TEC is correlated with the southward turning of the interplanetary magnetic field B_z. It is suggested that the electric fields produced by the dynamo process in the high-latitude region and the prompt penetration in the low-latitude region are responsible for TEC increases. During the June 16 event, dayside TEC values increase more than 15%. And the ionospheric F2-layer peak height (hmF2) was ˜300km higher and the vertical E×B drift (estimated from ground-based magnetometer equatorial electrojet delta H) showed downward drift, which may be due to the ionospheric disturbance dynamo electric field produced by the large amount of energy dissipation into high-latitude regions. In contr! ast, during November 20 event, the nightside TEC increases may be due to the prompt penetration westward electric field. The ionospheric F2-layer peak height was below 200km and the vertical E×B drift showed downward drift. Also, a strong correlation is observed between enhanced vertical TEC and enhanced interplanetary electric field. It is shown that, even though TEC increases are caused by the different processes, the electric field disturbances in the ionosphere play an important role in the variation of TEC over Korea.

  17. Stimulating endogenous cardiac repair

    PubMed Central

    Finan, Amanda; Richard, Sylvain

    2015-01-01

    The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration, a combination of these approaches could ameliorate the overall repair process to incorporate the participation of multiple cellular players. PMID:26484341

  18. Electric potential and electric field imaging

    NASA Astrophysics Data System (ADS)

    Generazio, E. R.

    2017-02-01

    The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field made be used for "illuminating" volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e-Sensor enhancements (ephemeral e-Sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

  19. 46 CFR 72.40-10 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Storm rails. 72.40-10 Section 72.40-10 Shipping COAST... and Guards § 72.40-10 Storm rails. (a) Suitable storm rails shall be installed in all passageways and at the deckhouse sides where passengers or crew might have normal access. Storm rails shall...

  20. 46 CFR 72.40-10 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Storm rails. 72.40-10 Section 72.40-10 Shipping COAST... and Guards § 72.40-10 Storm rails. (a) Suitable storm rails shall be installed in all passageways and at the deckhouse sides where passengers or crew might have normal access. Storm rails shall...

  1. 46 CFR 72.40-10 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Storm rails. 72.40-10 Section 72.40-10 Shipping COAST... and Guards § 72.40-10 Storm rails. (a) Suitable storm rails shall be installed in all passageways and at the deckhouse sides where passengers or crew might have normal access. Storm rails shall...

  2. 46 CFR 72.40-10 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 3 2011-10-01 2011-10-01 false Storm rails. 72.40-10 Section 72.40-10 Shipping COAST... and Guards § 72.40-10 Storm rails. (a) Suitable storm rails shall be installed in all passageways and at the deckhouse sides where passengers or crew might have normal access. Storm rails shall...

  3. 46 CFR 72.40-10 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Storm rails. 72.40-10 Section 72.40-10 Shipping COAST... and Guards § 72.40-10 Storm rails. (a) Suitable storm rails shall be installed in all passageways and at the deckhouse sides where passengers or crew might have normal access. Storm rails shall...

  4. The 1973 dust storm on Mars: Maps from hourly photographs

    NASA Technical Reports Server (NTRS)

    Martin, L. J.

    1975-01-01

    The hourly progress of the 1973 major Martian storm was mapped using photographic images from the International Planetary Patrol. Two series of 20 daily maps show the semi-hourly positions of the storm brightenings in red light and blue light. The maps indicate that the 1973 storm had many similarities to the 1971 storm.

  5. Criteria of interplanetary parameters causing intense magnetic storms (Dst of less than -100 nT)

    NASA Technical Reports Server (NTRS)

    Gonzalez, Walter D.; Tsurutani, Bruce T.

    1987-01-01

    An analysis of ISEE-3 field and plasma data shows that 10 intense magnetic storms that occurred in 1979 were caused by long-duration, large-amplitude (13-30 nT) and negative (less than -10 nT) IMF Bz events associated with interplanetary duskward-electric fields of greater than 5 mV/m. The results suggest that these criteria may be used as predictors of intense storms. A study of opposite polarity (northward) Bz events with the same criteria shows that their occurrence is similar both in number and in their relationship to interplanetary disturbances. The amplitudes of the storms were not found to vary with shock strengths.

  6. Clofibrate, calcium and cardiac muscle.

    PubMed

    Fairhurst, A S; Wickie, G; Peabody, T

    1982-03-01

    The anti-hyperlipidemic drug clofibrate produces negative inotropic effects and arrythmias in isolated perfused rabbit heart Langendorff preparations. In electrically stimulated rat left atria, clofibrate produces negative inotropic effects, the speed of onset and extent of which are decreased by raising the Ca concentration of the bathing medium. Sensitivity of isolated rat atria to clofibrate is not increased when the tissues are stimulated under slow Ca channel conditions, in which the tissues are activated by either isoproterenol or dibutyryl cyclic AMP, although sensitivity to clofibrate is decreased when atria are exposed to increasing concentrations of norepinephrine. Increasing the stimulation frequency of isolated guinea-pig atria to produce a positive treppe also decreases the inhibitory effect of clofibrate, while in rat atria the typical negative treppe is altered towards a positive treppe in presence of clofibrate. The effects of paired electrical stimulation are not diminished by the drug, suggesting that Ca release from the sarcoplasmic reticulum is not affected by clofibrate, although the drug inhibits the rate of Ca uptake by isolated cardiac sarcoplasmic reticulum and mitochondria. These results suggest that clofibrate has multiple effects on Ca functions in cardiac muscle.

  7. Radiation Belt Storm Probe Mission Trailer

    NASA Video Gallery

    With launch scheduled for 2012, the Radiation Belt Storm Probe (RBSP) are two identical spacecraft that will investigate the doughnut shaped Van Allen radiation belts, the first discovery of the sp...

  8. Rainfall Totals Over Storm Life of Matthew

    NASA Video Gallery

    This animation shows the amount of rainfall dropped by Hurricane Matthew over the life and track of the storm/ IMERG real time data covering the period from Sept. 28 through Oct. 10, 2016 show rain...

  9. Satellite Movie Sees Southern California Storms

    NASA Video Gallery

    This animation NOAA's GOES-West satellite imagery from Jan. 5 through Jan 7 shows the progression of storm systems in the Eastern Pacific Ocean that hit southern California and generated flooding a...

  10. Satellite Sees Birth of Tropical Storm Gordon

    NASA Video Gallery

    An animation of satellite observations from August 13-16, 2012, shows the birth of the Atlantic Ocean hurricane season's eighth tropical depression that strengthens into Tropical Storm Gordon. This...

  11. GMI Rainfall Data on Tropical Storm Adjali

    NASA Video Gallery

    This animation shows GMI rainfall data on Tropical Storm Adjali on Nov. 19, 2014 combined with cloud data from the METEOSAT-7 satellite. Rainfall was found to be falling at a rate of over 69 mm/hr ...

  12. GPM Flyby of Tropical Storm Dineo

    NASA Video Gallery

    This flyby animation of rainfall data within Tropical Cyclone Dineo was taken from NASA/JAXA's GPM satellite on Feb.16. Storms over Swaziland were dropping precipitation at a rate of over 86 mm (3....

  13. Tropical Storm Wali Seen by GOESWest

    NASA Video Gallery

    This animation of infrared and visible imagery from NOAA's GOES-West satellite from July 15 to 18 shows the birth of Tropical Storm Wali southeast of the Big Island of Hawaii on July 17. Credit: NA...

  14. Tropical Storm Gil - July 31, 2013

    NASA Video Gallery

    NASA's TRMM satellite traveled above intensifying Tropical Storm Gil on July 31 at 12:55 a.m. EDT. The TRMM satellite pass showed that Gil was already very well organized with intense bands of rain...

  15. Tropical Storm Gilma in Eastern Pacific

    NASA Video Gallery

    An animation of satellite observations shows the progression of Tropical Storm Gilma from August 7-10, 2012, along the coast of the Eastern Pacific Ocean. This visualization was created by the NASA...

  16. TRMM Sees California Storm Move East

    NASA Video Gallery

    This animation from Feb. 28 to Mar. 3 shows the movement of the rain associated with the storm system that soaked California. On March 3, precipitation (yellow) and snow cover (white/yellow) spread...

  17. GOES Movie of Tropical Storm Danielle

    NASA Video Gallery

    This animation NOAA's GOES-East satellite imagery from June 18 to 20 shows the development and movement Tropical Storm Danielle from the western Caribbean Sea into the Bay of Campeche/Gulf of Mexic...

  18. The Surprising Power of Solar Storms

    NASA Video Gallery

    NASA-funded researchers say a flurry of solar storms from March 8-10, 2012 dumped enough energy in Earth's upper atmosphere (our thermosphere absorbed 26 billion kWh of energy) to power every resid...

  19. GOES video of Tropical Storm Andrea

    NASA Video Gallery

    This NOAA GOES-East satellite animation shows the development of System 91L into Tropical Storm Andrea over the course of 3 days from June 4 to June 6, just after Andrea was officially designated a...

  20. GOES Satellite Movie of 2014 Winter Storms

    NASA Video Gallery

    This new animation of NOAA's GOES-East satellite imagery shows the movement of winter storms from January 1 to March 24 making for a snowier-than-normal winter along the U.S. East coast and Midwest...

  1. Storm sudden commencements and earthquakes

    NASA Astrophysics Data System (ADS)

    Lavrov, Ivan; Sobisevich, Aleksey; Guglielmi, Anatol

    2015-03-01

    We have investigated statistically the problem of possible impact of the geomagnetic storm sudden com-mencement (SSC) on the global seismic activity. SSC are used as reference points for comparative analysis of seismicity by the method of superposed epoch. We selected 405 earthquakes from 1973 to 2010 with M˜5 magnitudes from a representative part of USGS Catalog. The comparative analysis of seismicity was carried out at the intervals of ˜60 min relative to the reference point. With a high degree of reliability, it was found that before the reference point the number of earthquakes is noticeably greater than after it. In other words, the global seismicity is suppressed by SSC. We refer to some studies in which the chemical, thermal and force mechanisms of the electromagnetic field action on rocks are discussed. We emphasize the incompleteness of the study concerning the correlation between SSC and earthquakes because we still do not succeed in understanding and interpreting the relationship in terms of physics and mathematics. The study need to be continued to solve this problem of interest and importance.

  2. Magnetic Reconnection During Major Magnetospheric Storms

    NASA Astrophysics Data System (ADS)

    Hubert, B. A.; Milan, S. E.; Cowley, S. W. H.

    2014-12-01

    We combine imaging of the proton aurora from the SI12-IMAGE instrument with ionospheric convection measurement from the SuperDARN radar network to analyze the cycle of magnetic flux opening and closure of the Earth magnetosphere. Interaction between the solar wind and the Earth geomagnetic environment causes a reconfiguration of the magnetic field that connects the interplanetary magnetic field (IMF) to the geomagnetic field. This reconnection process produces open magnetic field lines (i.e. field lines of the magnetosphere that close through the interplanetary medium) that are dragged to the magnetotail by the solar wind flow, where they eventually reconnect again, back to a closed topology. The SI12 imaging of the Doppler-shifted Lyman-α emission of the proton aurora is used to estimate the location of the boundary separating open and closed field lines at ionospheric altitude. We then estimate the open magnetic flux of the Earth magnetosphere, encircled by this boundary. The rate of reconnection causing a variation of the open magnetic flux can be expressed as a voltage in application of Faraday's law. This voltage is measured along the open/closed field line boundary determined from the imaging data. The electric field associated with the voltage has two origins: motion of the boundary and the ionospheric field. We use the ionospheric electric field deduced from ionospheric convection measurement from the SuperDARN to estimate the reconnection voltage at the magnetopause (flux opening) and in the magnetotail (flux closure) accounting for the motion of the open/closed field line boundary determined from the SI12 images. The method is applied during several (strong) geomagnetic storms. These intervals are characterized by large values of open flux and reconnection rates, as a result of coupling between the solar wind and the geomagnetic environment. We present these results in terms of a magnetospheric mode that develops under strong coupling with the solar wind

  3. Tropical Storm Alberto, Seen Through New 'Eyes'

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Figure 1

    NASA's new CloudSat satellite captured its first tropical storm, Alberto, as it spun over the Gulf of Mexico the morning of June 12, 2006. This image comparison shows how CloudSat 'sees' such storms differently than conventional weather satellites. The CloudSat image (top of this page and bottom of figure 1) is compared with images obtained at nearly the same time from two National Oceanic and Atmospheric Administration National Weather Service tools that are mainstays for monitoring the development and movement of tropical cyclones: the NEXRAD storm detection radar, which maps out precipitation patterns for that portion of the storm that comes into its range, and the GOES-12 (Geostationary Operational Environmental Satellite) infrared imager, which is presented here to indicate the scale of the storm and the location where CloudSat overflies it. CloudSat sees the storm outside the range of NEXRAD and provides significantly greater vertical detail compared to the GOES satellite. NEXRAD, for example, can only see out to about 402 kilometers (250 nautical miles), and so could not see the portion of the storm that CloudSat was flying over at the time. GOES-12 only sees the very top of the clouds, and cannot provide any detail about what is being seen beneath the cloud tops.

    The CloudSat data show a storm that reaches about 16 kilometers (10 miles) in height and extends perhaps 1,000 kilometers (621 miles) in scale. The green line at the bottom of the CloudSat image is the radar echo of the Earth's surface. Where this line starts to disappear (change color) under the storm is where the rainfall is heaviest. Very heavy rainfall can be seen over about 400 kilometers (249 miles) of the satellite track. Cirrus clouds can also been seen out ahead of the storm (near letter A) -- this is also evident in the GOES-12 image. A smaller thunderstorm is visible in the CloudSat image under that cirrus cloud

  4. Semiannual variations of great geomagnetic storms: Solar sources of great storms. (Reannouncement with new availability information)

    SciTech Connect

    Cliver, E.W.; Crooker, N.U.; Cane, H.V.

    1992-01-01

    The authors report preliminary results of an investigation of the solar sources of 25 great geomagnetic storms with D sub st < or = {minus}250 nT occurring from 1957-1990. These storms exhibit a clear semiannual variation with 14 events occurring within {+-} 30 days of the equinoxes vs. 5 storms within {+-} 30 days of the solstices. This seasonal variation appears to result from a variable threshold for the size of a solar event required to produce a great geomagnetic storm, in the sense that weaker solar events, such as disappearing solar filaments, are more likely to produce great storms at the equinoxes than near the solstices. The great problem storms of the last four solar cycles, i.e., those storms lacking commensurate preceding solar activity, are all found to occur relatively near the equinoxes. Conversely, four of the five great storms that occurred near the solstices were preceded by truly outstanding solar flares. About half (11/25) of the great storms had obvious precursor geomagnetic activity, i.e., periods of approximately > 1 day with D sub st approximately < {minus}30 nT. The precursors can enable some weaker solar events to be more geoeffective than would otherwise be the case in two ways: (1) compression and amplification of pre-existing southward (precursor) fields by the transient shock, and (2) establishment of a lower D sub st baseline , making it easier for transient events to drive D sub st to values < or = {minus}250 nT.

  5. The effects of storms and storm-generated currents on sand beaches in Southern Maine, USA

    USGS Publications Warehouse

    Hill, H.W.; Kelley, J.T.; Belknap, D.F.; Dickson, S.M.

    2004-01-01

    Storms are one of the most important controls on the cycle of erosion and accretion on beaches. Current meters placed in shoreface locations of Saco Bay and Wells Embayment, ME, recorded bottom currents during the winter months of 2000 and 2001, while teams of volunteers profiled the topography of nearby beaches. Coupling offshore meteorological and beach profile data made it possible to determine the response of nine beaches in southern Maine to various oceanographic and meteorological conditions. The beaches selected for profiling ranged from pristine to completely developed and permitted further examination of the role of seawalls on the response of beaches to storms. Current meters documented three unique types of storms: frontal passages, southwest storms, and northeast storms. In general, the current meter results indicate that frontal passages and southwest storms were responsible for bringing sediment towards the shore, while northeast storms resulted in a net movement of sediment away from the beach. During the 1999-2000 winter, there were a greater percentage of frontal passages and southwest storms, while during the 2000-2001 winter, there were more northeast storms. The sediment that was transported landward during the 1999-2000 winter was reworked into the berm along moderately and highly developed beaches during the next summer. A northeast storm on March 5-6, 2001, resulted in currents in excess of 1 m s-1 and wave heights that reached six meters. The storm persisted over 10 high tides and caused coastal flooding and property damage. Topographic profiles made before and after the storm demonstrate that developed beaches experienced a loss of sediment volume during the storm, while sediment was redistributed along the profile on moderately developed and undeveloped beaches. Two months after the storm, the profiles along the developed beaches had not reached their pre-storm elevation. In comparison, the moderately developed and undeveloped beaches

  6. Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

    NASA Astrophysics Data System (ADS)

    Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

    2014-07-01

    Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

  7. Geomagnetic storm effect on the occurrence of ionospheric irregularities over African equatorial sector using GPS-TEC

    NASA Astrophysics Data System (ADS)

    Amaechi, Paul; Oyeyemi, Elijah; Akala, Andrew

    2016-07-01

    Total electron content (TEC) derived from Global Navigation Satellite Systems (GNSS) measurements provided by the International GNSS Service (IGS) network have been used to study the occurrence of large scale ionospheric irregularities over the African equatorial sector. The rate of change of TEC (ROT) as well as its standard deviation over five minutes (ROTI) were used to monitor the level of irregularities over 3 stations distributed across the three longitudinal sectors of Africa (eastern, central and western longitudinal sectors). The storm effect on irregularities occurrence has been studied in conjunction with the disturbance storm time (Dst) and the z component of the Interplanetary magnetic field (IMFBz) indices during four intense storms which were classified according to their season of occurrence during the year 2015. Irregularities were associated with GPS-TEC fluctuations as seen in the increased ROT and ROTI values especially in the post sunset period. Irregularities were inhibited over all the stations during the storm of March plausibly as a result of electric field conditioned by the southward turning of IMFBz during the pre and post midnight periods. The triggering of irregularities over the western and central stations and their inhibition over the eastern station during the storm of June was controlled by the ring current. The storm effect on irregularities was not evident over the western and central stations but inhibition of irregularities was observed over the eastern station during the storm of September.

  8. EVIDENCE FOR COMET STORMS IN METEORITE AGES

    SciTech Connect

    Perlmutter, S.; Muller, R.A.

    1987-10-01

    Clustering of cosmic-ray exposure ages of H chondritic meteorites occurs at 7 {+-} 3 and 30 {+-} 6 Myr ago. There is independent evidence that comet storms have occurred at the same times, based on the fossil record of family and genus extinctions, impact craters and glass, and geomagnetic reversals. We suggest that H chondrites were formed by the impact of shower comets on asteroids. The duration of the most recent comet shower was {le} 4 Myr, in agreement with storm theory.

  9. Ionospheric F-Region Storms: Unsolved Problems

    DTIC Science & Technology

    2006-06-01

    the largest solar - terrestrial storms ever observed, with an X17/4B flare on October 28, a solar wind velocity of nearly 2000 km/s and a minimum Dst...disturbance dynamo effects over low and equatorial lat- itude F-region, in Recurrent Magnetic Storms: Corotating Solar Wind Streams (B.T. Tsurutani, R.L...some of the more prominent anomalies observed in this region, including the heating effect below the magne- tospheric cusp, the subauroral electron

  10. Dust Storm, Red Sea and Saudi Arabia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Outlined against the dark blue water of the Red Sea, a prominent dust storm is making its way across the Red Sea into Saudi Arabia (22.0N, 39.0E) between the Islamic holy cities of Medinah and Mecca. Funneled through a gap in the coastal ranges of southern Sudan near the Ethiopian border, dust storms frequently will blow counter to the prevailing tropical easterly winds of the region.

  11. Ionospheric storm effects at subauroral latitudes - A case study

    NASA Technical Reports Server (NTRS)

    Proelss, G. W.; Brace, L. H.; Mayr, H. G.; Carignan, G. R.; Killeen, T. L.

    1991-01-01

    An attempt is made to classify ionospheric storm effects at subauroral latitudes according to their presumed origin. The storm of December 7/8, 1982, serves as an example. It is investigated using ionosonde, electron content, and DE 2 satellite data. The following effects are distinguished: (1) positive storm effects caused by traveling atmospheric disturbances, (2) positive storm effects caused by changes in the large-scale thermospheric wind circulation, (3) positive storm effects caused by the expansion of the polar ionization enhancement, (4) negative storm effects caused by perturbations of the neutral gas composition, and (5) negative storm effects caused by the equatorward displacement of the trough region.

  12. Ionospheric storm effects at subauroral latitudes: A case study

    SciTech Connect

    Proelss, G.W. ); Brace, L.H.; Mayr, H.G. ); Carignan, G.R.; Killeen, T.L. ); Klobuchar, J.A. )

    1991-02-01

    An attempt is made to classify ionospheric storm effects at subauroral latitudes according to their presumed origin. The storm of December 7/8, 1982, serves as an example. It is investigated using ionosonde, electron content, and DE 2 satellite data. The following effects are distinguished: (1) positive storm effects caused by traveling atmospheric disturbances, (2) positive storm effects caused by changes in the large-scale thermospheric wind circulation, (3) positive storm effects caused by the expansion of the polar ionization enhancement, (4) negative storm effects caused by perturbations of the neutral gas composition, and (5) negative storm effects caused by the equatorward displacement of the trough region.

  13. Field Evaluation of Low-E Storm Windows

    SciTech Connect

    Drumheller, S. Craig; Kohler, Christian; Minen, Stefanie

    2007-07-11

    A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single-pane windows were monitored over the period of one heating season. The homes were monitored with no storm windows and with new storm windows. The storm windows installed on four of the six homes included a hard coat, pyrolitic, low-e coating while the storm windows for the other two homeshad traditional clear glass. Overall heating load reduction due to the storm windows was 13percent with the clear glass and 21percent with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years forthe low-e storm windows.

  14. Low-E Storm Windows Gain Acceptance as a Home Weatherization Measure

    SciTech Connect

    Gilbride, Theresa L.; Cort, Katherine A.

    2016-05-16

    This article for Home Energy Magazine describes work by the U.S. Department of Energy to develop low-emissivity storm windows as an energy efficiency-retrofit option for existing homes. The article describes the low-emissivity invisible silver metal coatings on the glass, which reflect heat back into the home in winter or back outside in summer and the benefits of low-e storm windows including insulation, air sealing, noise blocking, protection of antique windows, etc. The article also describes Pacific Northwest National Laboratory's efforts on behalf of DOE to overcome market barriers to adoption of the technology, including performance validation studies in the PNNL Lab Homes, cost effectiveness analysis, production of reports, brochures, how-to guides on low-e storm window installation for the Building America Solution Center, and a video posted on YouTube. PNNL's efforts were reviewed by the Pacific Northwest Regional Technical Forum (RTF), which serves as the advisory board to the Pacific Northwest Electric Power Planning Council and Bonneville Power Administration. In late July 2015, the RTF approved the low-e storm window measure’s savings and specifications, a critical step in integrating low-e storm windows into energy-efficiency planning and utility weatherization and incentive programs. PNNL estimates that more than 90 million homes in the United States with single-pane or low-performing double-pane windows would benefit from the technology. Low-e storm windows are suitable not only for private residences but also for small commercial buildings, historic properties, and facilities that house residents, such as nursing homes, dormitories, and in-patient facilities. To further assist in the market transformation of low-e storm windows and other high-efficiency window attachments, DOE helped found the window Attachment Energy Rating Council (AERC) in 2015. AERC is an independent, public interest, non-profit organization whose mission is to rate, label

  15. Two-Step Forecast of Geomagnetic Storm Using Coronal Mass Ejection and Solar Wind Condition

    NASA Technical Reports Server (NTRS)

    Kim, R.-S.; Moon, Y.-J.; Gopalswamy, N.; Park, Y.-D.; Kim, Y.-H.

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz = -5 nT or Ey = 3 mV/m for t = 2 h for moderate storms with minimum Dst less than -50 nT) (i.e. Magnetic Field Magnitude, B (sub z) less than or equal to -5 nanoTeslas or duskward Electrical Field, E (sub y) greater than or equal to 3 millivolts per meter for time greater than or equal to 2 hours for moderate storms with Minimum Disturbance Storm Time, Dst less than -50 nanoTeslas) and a Dst model developed by Temerin and Li (2002, 2006) (TL [i.e. Temerin Li] model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90 percent) than the forecasts based on the TL model (87 percent). However, the latter produces better forecasts for 24 nonstorm events (88 percent), while the former correctly forecasts only 71 percent of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80 percent) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (n, i.e. cap operator - the intersection set that is comprised of all the elements that are common to both), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81 percent) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (?, i.e. cup operator - the union set that is comprised of all the elements of either or both

  16. Energetic particle precipitation in the Brazilian geomagnetic anomaly during the "Bastille Day storm" of July 2000

    NASA Astrophysics Data System (ADS)

    Nishino, M.; Makita, K.; Yumoto, K.; Miyoshi, Y.; Schuch, N. J.; Abdu, M. A.

    2006-05-01

    Ionospheric absorption associated with a great geomagnetic storm on July 15-16, 2000 (the "Bastille Day storm") was observed in the Brazilian geomagnetic anomaly using a two-dimensional 4×4 imaging riometer (IRIS). In the afternoon of July 15, weak absorption (~0.2 dB) was observed during the initial phase of the storm; large spatial-scale absorption exceeded the IRIS field of view (330×330 km). During the sharp magnetic decrease in the main phase of the storm, absorption was intensified (<0.5 dB) in the evening, showing a sheet structure with ~150 km latitudinal width and >330 km longitudinal elongation. Subsequently, absorption was intensified (~1 dB), having a small spatial-scale (~150 km) in the background sheet structure and a pronounced westward drift (~570 m s-1). In association with large magnetic fluctuations in the Bz component of the interplanetary magnetic field (IMF), the ground magnetic variation in the night sector showed large positive swings during the initial to main phases of the storm. With the subsequent southward turning of the IMF Bz, the ground magnetic variation in the evening sector showed rapid storm development. Particle fluxes measured by a geosynchronous satellite (L = ~6.6) demonstrated large enhancements of low-energy protons (50-400 keV) and probably electrons (50-225 keV) during the storm's initial phase. Particle fluxes from the low-altitude NOAA satellite (~870 km) indicated the invasion of low-energy particles into the region of L < 2 during the main phase of the storm. These results indicate that low-energy particles injected into the outer radiation belt in association with frequent and strong substorm occurrences, were transported into the inner radiation belt through direct convective access by the storm-induced electric fields during the storm's development. These particles then precipitated into the ionosphere over the Brazilian geomagnetic anomaly. Notably, the most intense absorption could be dominantly caused by

  17. Mapping Hurricane Rita inland storm tide

    USGS Publications Warehouse

    Berenbrock, Charles; Mason, Jr., Robert R.; Blanchard, Stephen F.; Simonovic, Slobodan P.

    2009-01-01

    Flood-inundation data are most useful for decision makers when presented in the context of maps of effected communities and (or) areas. But because the data are scarce and rarely cover the full extent of the flooding, interpolation and extrapolation of the information are needed. Many geographic information systems (GIS) provide various interpolation tools, but these tools often ignore the effects of the topographic and hydraulic features that influence flooding. A barrier mapping method was developed to improve maps of storm tide produced by Hurricane Rita. Maps were developed for the maximum storm tide and at 3-hour intervals from midnight (0000 hour) through noon (1200 hour) on September 24, 2005. The improved maps depict storm-tide elevations and the extent of flooding. The extent of storm-tide inundation from the improved maximum storm-tide map was compared to the extent of flood-inundation from a map prepared by the Federal Emergency Management Agency (FEMA). The boundaries from these two maps generally compared quite well especially along the Calcasieu River. Also a cross-section profile that parallels the Louisiana coast was developed from the maximum storm-tide map and included FEMA high-water marks.

  18. Scientists Track 'Perfect Storm' on Mars

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Two dramatically different faces of our Red Planet neighbor appear in these comparison images showing how a global dust storm engulfed Mars with the onset of Martian spring in the Southern Hemisphere. When NASA's Hubble Space Telescope imaged Mars in June, the seeds of the storm were caught brewing in the giant Hellas Basin (oval at 4 o'clock position on disk) and in another storm at the northern polar cap.

    When Hubble photographed Mars in early September, the storm had already been raging across the planet for nearly two months obscuring all surface features. The fine airborne dust blocks a significant amount of sunlight from reaching the Martian surface. Because the airborne dust is absorbing this sunlight, it heats the upper atmosphere. Seasonal global Mars dust storms have been observed from telescopes for over a century, but this is the biggest storm ever seen in the past several decades.

    Mars looks gibbous in the right photograph because it is 26 million miles farther from Earth than in the left photo (though the pictures have been scaled to the same angular size), and our viewing angle has changed. The left picture was taken when Mars was near its closest approach to Earth for 2001 (an event called opposition); at that point the disk of Mars was fully illuminated as seen from Earth because Mars was exactly opposite the Sun.

    Both images are in natural color, taken with Hubble's Wide Field Planetary Camera 2.

  19. Mapping hurricane rita inland storm tide

    USGS Publications Warehouse

    Berenbrock, C.; Mason, R.R.; Blanchard, S.F.

    2009-01-01

    Flood-inundation data are most useful for decision makers when presented in the context of maps of affected communities and (or) areas. But because the data are scarce and rarely cover the full extent of the flooding, interpolation and extrapolation of the information are needed. Many geographic information systems provide various interpolation tools, but these tools often ignore the effects of the topographic and hydraulic features that influence flooding. A barrier mapping method was developed to improve maps of storm tide produced by Hurricane Rita. Maps were developed for the maximum storm tide and at 3-h intervals from midnight (00:00 hours) through noon (12:00 hours) on 24 September 2005. The improved maps depict storm-tide elevations and the extent of flooding. The extent of storm-tide inundation from the improved maximum storm-tide map was compared with the extent of flood inundation from a map prepared by the Federal Emergency Management Agency (FEMA). The boundaries from these two maps generally compared quite well especially along the Calcasieu River. Also a cross-section profile that parallels the Louisiana coast was developed from the maximum storm-tide map and included FEMA high-water marks. ?? 2009 Blackwell Publishing Ltd.

  20. Solar storm effects on the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    Brain, David; Lillis, Robert; Peticolas, Laura; Luhmann, Janet G.

    Solar storms, including solar flares, solar energetic particles (SEPs), and coronal mass ejections (CMEs), may have a profound influence on planetary atmospheres left unprotected by global magnetic fields, such as Mars and Venus. Energy deposited in the upper atmosphere by photons and charged particles during storms should contribute to ionization and heating, driving chemistry and dynamics over periods of hours or days. There is observational evidence that the escape rate of planetary ions from the Venus atmosphere can increase by an order of magnitude during a storm. The planetary plasma environment may also change considerably during a storm (for example compressing during a passing CME and leading to a strongly magnetized ionosphere). We will present observations and model calculations of the influence of solar energetic particle events and CMEs on the atmosphere of Mars, focusing on three areas. First, we will present a correlation between the energy of auroral-like electron distributions observed by the Mars Global Surveyor (MGS) spacecraft and the presence of solar energetic particles. We will use an electron transport model to calculate the influence of these electron distributions on the nightside atmosphere. Second, we will present an analysis of electron pitch angle distributions recorded by MGS during solar storms, showing a substantial increase in ionization resulting from SEP impact. Third, we will present model calculations of the atmospheric energy deposition by solar energetic particles during a storm.