Sample records for anti-tachyarrhythmia burst pacing

  1. Response of pulmonary vein potentials to burst pacing. (United States)

    Vijayaraman, Pugazhendhi; Kok, Lai Chow; Shepard, Richard K; Wood, Mark A; Ellenbogen, Kenneth A


    Pulmonary vein potentials recorded at the ostia of pulmonary veins (PV) are a useful guide for segmental isolation of the PV in patients with atrial fibrillation (AF). Even during coronary sinus pacing at 600 ms, atrial (A) and PV potentials can overlap in 50-60% of patients making the accurate identification of PV potentials very difficult. Nineteen patients (M:F 15:4) with paroxysmal AF underwent segmental isolation of one or more PV. Coronary sinus (CS) pacing was performed at cycle lengths of 600/550/500/450/400/350/300 ms and bipolar electrograms were recorded from the 10 or 20 pole Lasso catheter placed at the atrial-PV junction in 27 pulmonary veins. Stimulus (S) to A, S-PVP and A-PVP intervals were measured during CS pacing at the different cycle lengths at sweep speed of 200 mm/sec. During CS pacing at 600 ms the A and PV potentials were significantly overlapped (A-PVP A-PVP > or = 25 ms) in 9 of the 15 veins where A and PV potentials overlapped and 21 of all 27 (78%) veins. In two patients pacing at 300 ms was associated with 2:1 conduction block from atrial to PV fascicle. Coronary sinus pacing at cycle length of 300 ms demonstrated better separation of A and PV potentials compared to pacing at 600 ms. This strategy is easier and less time consuming compared to extrastimuli testing. It also confirms that the electrophysiological properties of PV fascicles are different from that of the adjacent atrial musculature.

  2. Correlation between the sudden jump-like increases of the atrio-Hisian interval induced during burst atrial pacing and during programmed atrial stimulation in patients with atrioventricular nodal reentrant tachycardia. (United States)

    Bayraktarova, Iskra H; Stoyanov, Milko K; Kunev, Boyan T; Shalganov, Tchavdar N


    To study the correlation between the sudden prolongations of the atrio-Hisian (AH) interval with ≥50 ms during burst and programmed atrial stimulation, and to define whether the AH jump during burst atrial pacing is a reliable diagnostic criterion for dual AV nodal physiology. Retrospective data on 304 patients with preliminary ECG diagnosis of AV nodal reentrant tachycardia (AVNRT), confirmed during electrophysiological study, was analyzed for the presence of AH jump during burst and programmed atrial stimulation, and for correlation between the pacing modes for inducing the jump. Wilcoxon signed-ranks test and Spearman's bivariate correlation coefficient were applied, significant was P-value <0.05. The population was aged 48.5 ± 15.7 (12-85) years; males were 38.5%. AH jump occurred during burst atrial pacing in 81% of the patients, and during programmed stimulation - in 78%, P = 0.366. In 63.2% AH jump was induced by both pacing modes; in 17.8% - only by burst pacing; in 14.8% - only by programmed pacing; in 4.2% there was no inducible jump. There was negative correlation between both pacing modes, ρ = -0.204, Р<0.001. Burst and programmed atrial stimulation separately prove the presence of dual AV nodal physiology in 81 and 78% of the patients with AVNRT, respectively. There is negative correlation between the two pacing modes, allowing the combination of the two methods to prove diagnostic in 95.8% of the patients. Copyright © 2017 Indian Heart Rhythm Society. Production and hosting by Elsevier B.V. All rights reserved.

  3. Temporary pacing

    Directory of Open Access Journals (Sweden)

    L.J. Workman


    Full Text Available Artificial cardiac pacing, the use of electrical stimuli to cause contraction of heart muscle, is a sophisticated therapeutic and diagnostic tool. Its rapid technologic improvement since first developed in the late 1930’s by Hyman, has made it possible not only to avoid certain cases of death due to heart block, but also to extend and improve the quality of life. Pacemaker therapy is generally used to treat heart rate or rhythm disturbances, being either tachy- or bradyarrhythmias that produce a detrimental drop in cardiac output. Of the many different types of pacemakers and electrodes currently available, ventricular demand pacing is the most commonly used.

  4. A Simulation Study of Paced TCP (United States)

    Kulik, Joanna; Coulter, Robert; Rockwell, Dennis; Partridge, Craig


    In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

  5. Pacing failure caused by automatic pacing threshold adjustment system

    Directory of Open Access Journals (Sweden)

    Jun Kishihara


    Full Text Available Ventricular capture management is an automatic pacing threshold adjustment algorithm that automatically measures pacing threshold through detection of the evoked response after a pacing stimulus. Although it is principally designed to save device battery under the maintenance of the patient׳s safety, we experienced a rare case with serious pacing failure due to a weakness of this algorithm. This pacing failure might be explained by a large variation in the ventricular pacing threshold depending on the atrioventricular interval and daily variation of pacing threshold and concomitant steroid use in this patient. Keywords: Automatic pacing threshold adjustment algorithm, Pacing failure

  6. Temporary internal pacing. (United States)

    Ortiz Díaz-Miguel, R; Gómez Grande, M L


    Technology and insertion techniques for cardiac temporary internal pacing have experienced a remarkable development over the last few years. Despite this fact, the procedure continues to have potentially fatal associated complications. Temporary internal pacing is indicated for the treatment of bradyarrhythmias or tachyarrhythmias refractory to conventional treatment, or arrhythmias causing cardiovascular or clinical instability of the patient. On the other hand, the indications of temporary cardiac pacing are far less well defined than those of permanent pacing. Since the decision of implementing temporary pacing is complex and delicate, it should always be carefully considered, and over-indication should be avoided. We must base these decisions on robust knowledge of the arrhythmias that may benefit from temporary internal pacing, and should also acquire the habit of considering external temporary pacing among other less aggressive treatments, and to make the best use of new technologies such as echocardiography that add accuracy to the procedure. Copyright © 2013 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  7. Pacing stress echocardiography

    Directory of Open Access Journals (Sweden)

    Agrusta Marco


    Full Text Available Abstract Background High-rate pacing is a valid stress test to be used in conjunction with echocardiography; it is independent of physical exercise and does not require drug administration. There are two main applications of pacing stress in the echo lab: the noninvasive detection of coronary artery disease through induction of a regional transient dysfunction; and the assessment of contractile reserve through peak systolic pressure/ end-systolic volume relationship at increasing heart rates to assess global left ventricular contractility. Methods The pathophysiologic rationale of pacing stress for noninvasive detection of coronary artery disease is obvious, with the stress determined by a controlled increase in heart rate, which is a major determinant of myocardial oxygen demand, and thereby tachycardia may exceed a fixed coronary flow reserve in the presence of hemodynamically significant coronary artery disease. The use of pacing stress echo to assess left ventricular contractile reserve is less established, but promising. Positive inotropic interventions are mirrored by smaller end-systolic volumes and higher end-systolic pressures. An increased heart rate progressively increases the force of ventricular contraction (Bowditch treppe or staircase phenomenon. To build the force-frequency relationship, the force is determined at different heart rate steps as the ratio of the systolic pressure (cuff sphygmomanometer/end-systolic volume index (biplane Simpson rule. The heart rate is determined from ECG. Conclusion Two-dimensional echocardiography during pacing is a useful tool in the detection of coronary artery disease. Because of its safety and ease of repeatability noninvasive pacing stress echo can be the first-line stress test in patients with permanent pacemaker. The force-frequency can be defined as up- sloping (normal when the peak stress pacing systolic pressure/end-systolic volume index is higher than baseline and intermediate stress

  8. PACE Status Update

    Energy Technology Data Exchange (ETDEWEB)

    M., Zimring,; Hoffman, I.; Fuller, M.


    The Federal Housing Finance Agency (FHFA) regulates Fannie Mae, Freddie Mac, and the 12 Federal Home Loan Banks (the government-sponsored enterprises - GSEs). On July 6, 2010, FHFA and the Office of the Comptroller of the Currency (OCC) concluded that Property Assessed Clean Energy (PACE) programs 'present significant safety and soundness concerns' to the housing finance industry. This statement came after a year of discussions with state and federal agencies in which PACE, a novel mechanism for financing energy efficiency and renewable energy improvements, has gone from receiving support from the White House, canonization as one of Scientific American's 'World Changing Ideas' and legislative adoption in 24 states to questionable relevance, at least in the residential sector. Whether PACE resumes its expansion as an innovative tool for financing energy efficiency and clean generation depends on outcomes in each of the three branches of government - discussions on a PACE pilot phase among federal agencies, litigation in federal court, and legislation in Congress - all highly uncertain. This policy brief addresses the practical impacts of these possible outcomes on existing and emerging PACE programs across the United States and potential paths forward.

  9. [Advances in cardiac pacing]. (United States)

    de Carranza, María-José Sancho-Tello; Fidalgo-Andrés, María Luisa; Ferrer, José Martínez; Mateas, Francisco Ruiz


    This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed. Copyright © 2012 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  10. Recent developments in cardiac pacing. (United States)

    Rodak, D J


    Indications for cardiac pacing continue to expand. Pacing to improve functional capacity, which is now common, relies on careful patient selection and technical improvements, such as complex software algorithms and diagnostic capabilities.

  11. A dual-chamber pacing mode to minimize ventricular pacing

    Directory of Open Access Journals (Sweden)

    Peter Rakovec


    Full Text Available Background: Though patients with sick sinus syndrome theoretically need an atrial pacemaker only, they usually receive a ventricular or a dual-chamber pacemaker because of possible developement of atrioventricular conduction abnormalities. Right ventricular pacing produces left bundle branch block (i.e. pacing-induced ventricular desynchronization, promoting heart failure and atrial fibrillation. This problem can be solved by a special pacing mode which on one hand preserves the safety of dual-chamber pacing and on the other hand minimizes right ventricular pacing.

  12. TCP Pacing Developed (United States)

    Ivancic, William D.


    Transmission control protocol (TCP) was conceived and designed to run over a variety of communication links, including wireless and high-bandwidth links. However, with recent technological advances in satellite and fiber-optic networks, researchers are reevaluating the flexibility of TCP. The TCP pacing and packet pair probing implementation may help overcome two of the major obstacles identified for efficient bandwidth utilization over communication links with large delay-bandwidth products.

  13. Pacing for Vasovagal Syncope

    Directory of Open Access Journals (Sweden)

    Nevin T Wijesekera


    Full Text Available Vasovagal syncope is a common condition, usually associated with a benign prognosis. Most sufferers experience only occasional symptoms, and can be treated with reassurance and lifestyle advice. However, a minority of patients are debilitated by frequent fainting that can infringe on daily living, or even mimic sudden death. This has been termed "malignant" vasovagal syncope because of the associated falls and physical injury. In these cases, a more interventional approach may be appropriate. Pharmacological measures have been the mainstay of treatment for recurrent vasovagal syncope: beta-blockers (e.g. atenolol, serotonin reuptake inhibitors (e.g. paroxetine, certain vasoconstricting drugs (e.g. midodrine and fluid retaining agents (e.g. fludrocortisone have been of particular interest. However, there is only mixed support from randomised controlled trials for the efficacy of these agents in preventing vasovagal syncope. 1,2,3 In the last few years, cardiac pacing has been advocated for the treatment of some forms of vasovagal syncope. This article reviews the literature and discusses the indications for pacing in vasovagal syncope.

  14. Optimal Cardiac Resynchronization Therapy Pacing Rate in Non-Ischemic Heart Failure Patients

    DEFF Research Database (Denmark)

    Ghotbi, Adam Ali; Sander, Mikael; Køber, Lars


    BACKGROUND: The optimal pacing rate during cardiac resynchronization therapy (CRT) is unknown. Therefore, we investigated the impact of changing basal pacing frequencies on autonomic nerve function, cardiopulmonary exercise capacity and self-perceived quality of life (QoL). METHODS: Twelve CRT...... by microneurography (MSNA), peak oxygen consumption (pVO2), N-terminal pro-brain natriuretic peptide (p-NT-proBNP), echocardiography and QoL. RESULTS: DDD-80 pacing for 3 months increased the mean heart rate from 77.3 to 86.1 (p = 0.001) and reduced sympathetic activity compared to DDD-60 (51±14 bursts/100 cardiac...

  15. Sensors for rate responsive pacing

    Directory of Open Access Journals (Sweden)

    Simonetta Dell’Orto


    Full Text Available Advances in pacemaker technology in the 1980s have generated a wide variety of complex multiprogrammable pacemakers and pacing modes. The aim of the present review is to address the different rate responsive pacing modalities presently available in respect to physiological situations and pathological conditions. Rate adaptive pacing has been shown to improve exercise capacity in patients with chronotropic incompetence. A number of activity and metabolic sensors have been proposed and used for rate control. However, all sensors used to optimize pacing rate metabolic demands show typical limitations. To overcome these weaknesses the use of two sensors has been proposed. Indeed an unspecific but fast reacting sensor is combined with a more specific but slower metabolic one. Clinical studies have demonstrated that this methodology is suitable to reproduce normal sinus behavior during different types and loads of exercise. Sensor combinations require adequate sensor blending and cross checking possibly controlled by automatic algorithms for sensors optimization and simplicity of programming. Assessment and possibly deactivation of some automatic functions should be also possible to maximize benefits from the dual sensor system in particular conditions. This is of special relevance in patient whose myocardial contractility is limited such as in subjects with implantable defibrillators and biventricular pacemakers. The concept of closed loop pacing, implementing a negative feedback relating pacing rate and the control signal, will provide new opportunities to optimize dual-sensors system and deserves further investigation. The integration of rate adaptive pacing into defibrillators is the natural consequence of technical evolution.

  16. The Drift Burst Hypothesis


    Christensen, Kim; Oomen, Roel; Renò, Roberto


    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...

  17. Factors influencing pacing in triathlon

    Directory of Open Access Journals (Sweden)

    Wu SSX


    Full Text Available Sam SX Wu,1 Jeremiah J Peiffer,2 Jeanick Brisswalter,3 Kazunori Nosaka,1 Chris R Abbiss1 1Centre for Exercise and Sports Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, WA, Australia; 2School of Psychology and Exercise Science, Murdoch University, Perth, WA, Australia; 3Laboratory of Human Motricity, Education Sport and Health, University of Nice Sophia Antipolis, Nice, France Abstract: Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. Keywords: cycle, endurance, multisport, pacing strategy, run, swim

  18. Diagnostic accuracy of pace spikes in the electrocardiogram to diagnose paced rhythm

    DEFF Research Database (Denmark)

    Andersson, Hedvig Bille; Hansen, Marco Bo; Thorsberger, Mads


    OBJECTIVE: To determine how often cardiac resynchronization therapy (CRT) pacing systems generate visible pace spikes in the electrocardiogram (ECG). METHODS: In 46 patients treated with CRT pacing systems, we recorded ECGs during intrinsic rhythm, atrial pacing and ventricular pacing. ECGs were...

  19. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    . We then develop a non-parametric test statistic that allows for the identification of drift bursts from noisy high-frequency data. We apply this methodology to a comprehensive set of tick data and show that drift bursts form an integral part of the price dynamics across equities, fixed income......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  20. Pace studying worldwide coke production

    International Nuclear Information System (INIS)



    Pace Consultants Inc., Houston, has started a multiclient study of world-wide petroleum coke production, examining environmental initiatives and eventually forecasting prices of fuel grade coke. Pace expects coker expansions, increased operating severity, and reduced cycle times to boost coke supply to more than 50 million metric tons/year in 2000, compared with 39.7 million metric tons in 1992. Increased supply and tightened environmental rules in countries consuming large amounts of petroleum coke will be the main factors affecting coke markets. The paper discusses coke quality and the Japanese market

  1. Critical Bursts in Filtration (United States)

    Bianchi, Filippo; Thielmann, Marcel; de Arcangelis, Lucilla; Herrmann, Hans Jürgen


    Particle detachment bursts during the flow of suspensions through porous media are a phenomenon that can severely affect the efficiency of deep bed filters. Despite the relevance in several industrial fields, little is known about the statistical properties and the temporal organization of these events. We present experiments of suspensions of deionized water carrying quartz particles pushed with a peristaltic pump through a filter of glass beads measuring simultaneously the pressure drop, flux, and suspension solid fraction. We find that the burst size distribution scales consistently with a power law, suggesting that we are in the presence of a novel experimental realization of a self-organized critical system. Temporal correlations are present in the time series, like in other phenomena such as earthquakes or neuronal activity bursts, and also an analog to Omori's law can be shown. The understanding of burst statistics could provide novel insights in different fields, e.g., in the filter and petroleum industries.

  2. GLAST's GBM Burst Trigger (United States)

    Band, D.; Briggs, M.; Connaughton, V.; Kippen, M.; Preece, R.


    The GLAST Burst Monitor (GBM) will detect and localize bursts for the GLAST mission, and provide the spectral and temporal context in the traditional 10 keV to 25 MeV band for the high energy observations by the Large Area Telescope (LAT). The GBM will use traditional rate triggers in up to three energy bands, and on a variety of timescales between 16 ms and 16 s.

  3. Electrocardiographic features: Various atrial site pacing

    Directory of Open Access Journals (Sweden)

    Asit Das


    Full Text Available Atrial pacing is done for either symptomatic sinus node dysfunction (SND or for maintenance of atrio-ventricular synchrony in a dual chamber pacemaker. Conventionally, atrial lead is placed in the right atrial appendage. Atrial conduction disorder in patients with permanent pacing results in higher incidence of atrial fibrillation. Atrial septal pacing has emerged as a solution to this problem. So, it is extremely important to understand the different features of paced P wave from various atrial pacing sites. Conventional right atrial appendage pacing in presence of atrial conduction disorder results in marked latency with prolonged P wave duration with reduced amplitude. The morphology is similar to sinus rhythm. Atrial septal pacing causes short and sharp P wave with negative polarity in inferior leads and positive polarity in lead V1 in lower septal pacing, whereas positive polarity in inferior leads and negative polarity in lead V1 during pacing from upper septum.

  4. Science Unit Plans. PACE '94. (United States)

    Schoon, Kenneth J., Ed.; Wiles, Clyde A., Ed.

    This booklet contains mathematics unit plans for Biology, Chemistry, and Physical Science developed by PACE (Promoting Academic Excellence In Mathematics, Science & Technology for Workers of the 21st Century). Each unit plan contains suggested timing, objectives, skills to be acquired, workplace relationships, learning activities with suggested…

  5. A Burst to See (United States)


    On 19 March, Nature was particularly generous and provided astronomers with the wealth of four gamma-ray bursts on the same day. But that was not all: one of them is the most luminous object ever observed in the Universe. Despite being located in a distant galaxy, billions of light years away, it was so bright that it could have been seen, for a brief while, with the unaided eye. ESO PR Photo 08a/08 ESO PR Photo 08a/08 The REM Telescope and TORTORA Camera Gamma-ray bursts (GRBs) are short flashes of energetic gamma-rays lasting from less than a second to several minutes. They release a tremendous quantity of energy in this short time making them the most powerful events since the Big Bang. It is now widely accepted that the majority of the gamma-ray bursts signal the explosion of very massive, highly evolved stars that collapse into black holes. Gamma-ray bursts, which are invisible to our eyes, are discovered by telescopes in space. After releasing their intense burst of high-energy radiation, they become detectable for a short while in the optical and in the near-infrared. This 'afterglow' fades very rapidly, making detailed analysis possible for only a few hours after the gamma-ray detection. This analysis is important in particular in order to determine the GRB's distance and, hence, intrinsic brightness. The gamma-ray burst GRB 080319B was detected by the NASA/STFC/ASI Swift satellite. "It was so bright that it almost blinded the Swift instruments for a while," says Guido Chincarini, Italian principal investigator of the mission. A bright optical counterpart was soon identified in the Boötes Constellation (the "Bear Driver" or "Herdsman"). A host of ground-based telescopes reacted promptly to study this new object in the sky. In particular, the optical emission was detected by a few wide-field cameras on telescopes that constantly monitor a large fraction of the sky, including the TORTORA camera in symbiosis with the 0.6-m REM telescope located at La Silla

  6. Optothermally actuated capillary burst valve

    DEFF Research Database (Denmark)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders


    We demonstrate the optothermal actuation of individual capillary burst valves in an all-polymer microfluidic device. The capillary burst valves are realised in a planar design by introducing a fluidic constriction in a microfluidic channel of constant depth. We show that a capillary burst valve can...

  7. The Double Firing Burst (United States)


    Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth. Uncovering the disc ESO PR Photo 28/08 A Gamma-Ray Burst with Two Jets Read more on this illuminating blast in the additional story. GRB 080319B was so intense that, despite happening halfway across the Universe, it could have been seen briefly with the unaided eye (ESO 08/08). In a paper to appear in the 11 September issue of Nature, Judith Racusin of Penn State University, Pennsylvania (USA), and a team of 92 co-authors report observations across the electromagnetic spectrum that began 30 minutes before the explosion and followed it for months afterwards. "We conclude that the burst's extraordinary brightness arose from a jet that shot material almost directly towards Earth at almost the speed of light - the difference is only 1 part in 20 000," says Guido Chincarini, a member of the team. Gamma-ray bursts are the Universe's most luminous explosions. Most occur when massive stars run out of fuel. As a star collapses, it creates a black hole or neutron star that, through processes not fully understood, drives powerful gas jets outward. As the jets shoot into space, they strike gas previously shed by the star and heat it, thereby generating bright afterglows. The team believes the jet directed toward Earth contained an ultra-fast component just 0.4 degrees across (this is slightly smaller than the apparent size of the Full Moon). This jet is contained within another slightly less energetic jet about 20 times wider. The broad component is more typical of other bursts. "Perhaps every gamma-ray burst has a narrow jet, but astronomers miss it most of the time," says team member Stefano Covino. "We happened to view this monster down the barrel of the very narrow and energetic jet, and the chance for

  8. [Permanent cardiac pacing. Present possibilities and perspectives]. (United States)

    Novák, M


    Cardiac pacing is reckoned to be one of the most successful branches of medicine in the second half of the 20th century. Indications for single chamber ventricular pacing are getting gradually restricted. This early pacing mode, which was used in 1958 for the first time, has been recently replaced from modern modes: for atrial, dual chamber and rate adaptive ones. Not only these most recent methods prevent from bradycardia but they also meet demands of modern cardiac pacing, i.e. to restore the synchronization of the atriums and the ventricles and to restore the frequency response. So-called physiological pacing improves both the well-being and the survival of patients and it has also extended pacing indications to the non-arrhythmic ones: first and foremost to the cardiomyopathies. It is dual chamber pacing, the artificial biosensors, various kinds of counters and monitoring functions that enhance the energy consumption. Both low-threshold pacing leads and an automatic adjustment of the pulse energy are helpful in extending the longevity of tiny lithium-powered pacemakers of these days. Current dual chamber rate responsive devices represent an important first step towards a fully automatic smart pacemaker of the future. Such an intelligent pulse generator with several sensors will be operating in the DDDR mode checking automatically the pacing threshold and switching its pacing mode according to pathophysiological requirements.

  9. Burst Populations and Detector Sensitivity (United States)

    Band, David L.


    The F(sub T) (peak bolometric photon flux) vs. E(sub p) (peak energy) plane is a powerful tool to compare the burst populations detected by different detectors. Detector sensitivity curves in this plane demonstrate which burst populations the detectors will detect. For example, future CZT-based detectors will show the largest increase in sensitivity for soft bursts, and will be particularly well- suited to study X-ray rich bursts and X-ray Flashes. Identical bursts at different redshifts describe a track in the F(sub T)-E(sub p) plane.

  10. Gamma-ray bursts

    CERN Document Server

    Wijers, Ralph A M J; Woosley, Stan


    Cosmic gamma ray bursts (GRBs) have fascinated scientists and the public alike since their discovery in the late 1960s. Their story is told here by some of the scientists who participated in their discovery and, after many decades of false starts, solved the problem of their origin. Fourteen chapters by active researchers in the field present a detailed history of the discovery, a comprehensive theoretical description of GRB central engine and emission models, a discussion of GRB host galaxies and a guide to how GRBs can be used as cosmological tools. Observations are grouped into three sets from the satellites CGRO, BeppoSAX and Swift, and followed by a discussion of multi-wavelength observations. This is the first edited volume on GRB astrophysics that presents a fully comprehensive review of the subject. Utilizing the latest research, Gamma-ray Bursts is an essential desktop companion for graduate students and researchers in astrophysics.

  11. Gamma-ray bursts. (United States)

    Gehrels, Neil; Mészáros, Péter


    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens of seconds, and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this Review, we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglow.

  12. Gamma Ray Bursts (United States)

    Gehrels, Neil; Meszaros, Peter


    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  13. A Leadless Intracardiac Transcatheter Pacing System

    NARCIS (Netherlands)

    Reynolds, Dwight; Duray, Gabor Z.; Omar, Razali; Soejima, Kyoko; Neuzil, Petr; Zhang, Shu; Narasimhan, Calambur; Steinwender, Clemens; Brugada, Josep; Lloyd, Michael; Roberts, Paul R.; Sagi, Venkata; Hummel, John; Bongiorni, Maria Grazia; Knops, Reinoud E.; Ellis, Christopher R.; Gornick, Charles C.; Bernabei, Matthew A.; Laager, Verla; Stromberg, Kurt; Williams, Eric R.; Hudnall, J. Harrison; Ritter, Philippe; Duray, Gabor Zoltan; Roberts, Paul; Gornick, Charles; Ellis, Christopher; Gonzalez, Efrain; Boersma, Lucas V. A.; Chinitz, Larry; Bernabei, Matthew; Shinn, Timothy; Jones, Randy; Schoenhard, John; Kusano, Kengo; Philippon, Francois; Atwater, Brett; Voigt, Andrew; Asano, Taku; Kowal, Robert; Simmers, Timothy Alexander; Milasinovic, Goran; Bahl, Vinay Kumar; Seger, John; Shehata, Michael; Thibault, Bernard T.; Ishikawa, Toshiyuki; Sra, Jasbir; Giocondo, Michael; Johnson, Eric; Wilkoff, Bruce; Collier, Jack; Hill, John; Vardas, Panos E.; Mittal, Suneet; Grubman, Eric; Ferguson, John; Svendsen, Jesper Hastrup; Chin, Ashley; Rogers, John; Jadonath, Ram; Tyagi, Sanjay; Ghali, Magdi; Coyne, Robert; Esberg, Douglas; Duray, Gabor


    A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing.

  14. Web Tools: Keeping Learners on Pace (United States)

    Kosloski, Mickey


    One of the greatest challenges in teaching technology and engineering is pacing. Some students grasp new technological concepts quickly, while others need repetition and may struggle to keep pace. This poses an obstacle for the technology and engineering teacher, and is particularly true when teaching students to build a website. However, there…

  15. UWB dual burst transmit driver (United States)

    Dallum, Gregory E [Livermore, CA; Pratt, Garth C [Discovery Bay, CA; Haugen, Peter C [Livermore, CA; Zumstein, James M [Livermore, CA; Vigars, Mark L [Livermore, CA; Romero, Carlos E [Livermore, CA


    A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

  16. 42 CFR 460.60 - PACE organizational structure. (United States)


    ... 42 Public Health 4 2010-10-01 2010-10-01 false PACE organizational structure. 460.60 Section 460... ELDERLY (PACE) PACE Administrative Requirements § 460.60 PACE organizational structure. (a) A PACE... planning a change in organizational structure must notify CMS and the State administering agency, in...

  17. Unihemispheric burst suppression

    Directory of Open Access Journals (Sweden)

    Edward C. Mader Jr.


    Full Text Available Burst suppression (BS consists of bursts of high-voltage slow and sharp wave activity alternating with periods of background suppression in the electroencephalogram (EEG. When induced by deep anesthesia or encephalopathy, BS is bihemispheric and is often viewed as a non-epileptic phenomenon. In contrast, unihemispheric BS is rare and its clinical significance is poorly understood. We describe here two cases of unihemispheric BS. The first patient is a 56-year-old woman with a left temporoparietal tumor who presented in convulsive status epilepticus. EEG showed left hemispheric BS after clinical seizure termination with lorazepam and propofol. The second patient is a 39-year-old woman with multiple medical problems and a vague history of seizures. After abdominal surgery, she experienced a convulsive seizure prompting treatment with propofol. Her EEG also showed left hemispheric BS. In both cases, increasing the propofol infusion rate resulted in disappearance of unihemispheric BS and clinical improvement. The prevailing view that typical bihemispheric BS is non-epileptic should not be extrapolated automatically to unihemispheric BS. The fact that unihemispheric BS was associated with clinical seizure and resolved with propofol suggests that, in both cases, an epileptic mechanism was responsible for unihemispheric BS.

  18. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Abstract. After a short review of gamma ray bursts (GRBs), we discuss the physical implications of strong statistical correlations seen among some of the parameters of short duration bursts (90 < 2 s). Finally, we conclude with a brief sketch of a new unified model for long and short GRBs.

  19. Bursts de raios gama (United States)

    Braga, J.


    Nos últimos anos, graças principalmente aos dados obtidos pelo Compton Gamma-Ray Observatory e pelo satélite ítalo-holandês BeppoSAX, grandes avanços foram obtidos no nosso conhecimento sobre os fascinantes e enigmáticos fenômenos conhecidos por "bursts"de raios gama. Neste trabalho é feita uma revisão sobre a fenomenologia desses misteriosos objetos e são apresentados os desenvolvimentos recentes nessa área palpitante da astrofísica moderna, ressaltando tanto os resultados observacionais obtidos até o momento quanto os modelos teóricos propostos para explixá-los.

  20. Burst Detector Sensitivity: Past, Present and Future (United States)

    Band, David L.


    I compare the burst detection sensitivity of CGRO's BATSE, Swift's BAT, the GLAST Burst Monitor (GBM) and EXIST as a function of a burst s spectrum and duration. A detector's overall burst sensitivity depends on its energy sensitivity and set of accumulations times (Delta)t; these two factors shape the detected burst population. For example, relative to BATSE, the BAT s softer energy band decreases the detection rate of short, hard bursts, while the BAT s longer accumulation times increase the detection rate of long, soft bursts. Consequently, Swift is detecting long, low fluence bursts (2-3 x fainter than BATSE).

  1. PACE: Power-Aware Computing Engines

    National Research Council Canada - National Science Library

    Asanovic, Krste


    This report describes the PACE project whose objective was to reduce the energy consumption of microprocessors by exploiting compile time knowledge to reduce run-time switching activity and to power down unneeded blocks...

  2. Outback is put through its paces. (United States)


    Ashley Rubens, winner of the competition to find the BVA member facing the toughest driving conditions in the UK, has spent the past few months putting a Subaru Outback through its paces. British Veterinary Association.

  3. Cardiac pacing in pediatrics: Is still the right ventricle the optimal pacing site?

    Directory of Open Access Journals (Sweden)

    Michel Cabrera Ortega


    Full Text Available Permanent cardiac pacing is frequently indicated in pediatric patients due to atrioventricular block. Traditionally, the right ventricle has been the pacing site because it is readily accessible, and provides lead stability and optimal chronic pacing thresholds. However, it is associated with a dyssynchrony pattern of ventricular activation, that may cause remodeling and impairment of left ventricular function. In pediatric patients, paced from an early age and with a long life expectancy, the preservation of cardiac function is a premise. Therefore, the prevention of dyssynchrony, using possible alternative sites, is not just a priority, is a challenge. The aim of the article is to show the effects of chronic right ventricular pacing as well as the evidence of benefits provided by alternatives pacing sites in pediatric population and their clinical and practical implications.

  4. Optogenetic pacing in Drosophila melanogaster (Conference Presentation) (United States)

    Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao


    A non-invasive, contact-less cardiac pacing technology can be a powerful tool in basic cardiac research and in clinics. Currently, electrical pacing is the gold standard for cardiac pacing. Although highly effective in controlling the cardiac function, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its capabilities. Optical pacing of heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids shortcomings in electrical stimulation. Optical coherence tomography has been proved to be an effective technique in non-invasive imaging in vivo with ultrahigh resolution and imaging speed. In the last several years, non-invasive specific optical pacing in animal hearts has been reported in quail, zebrafish, and rabbit models. However, Drosophila Melanogaster, which is a significant model with orthologs of 75% of human disease genes, has rarely been studied concerning their optical pacing in heart. Here, we combined optogenetic control of Drosophila heartbeat with optical coherence microscopy (OCM) technique for the first time. The light-gated cation channel, channelrhodopsin-2 (ChR2) was specifically expressed by transgene as a pacemaker in drosophila heart. By stimulating the pacemaker with 472 nm pulsed laser light at different frequencies, we achieved non-invasive and more specific optical control of the Drosophila heart rhythm, which demonstrates the wide potential of optical pacing for studying cardiac dynamics and development. Imaging capability of our customized OCM system was also involved to observe the pacing effect visually. No tissue damage was found after long exposure to laser pulses, which proved the safety of optogenetic control of Drosophila heart.

  5. Magnetron: Fitting bursts from magnetars (United States)

    Huppenkothen, Daniela; Brewer, Brendon J.; Hogg, David W.; Murray, Iain; Frean, Marcus


    Magnetron, written in Python, decomposes magnetar bursts into a superposition of small spike-like features with a simple functional form, where the number of model components is itself part of the inference problem. Markov Chain Monte Carlo (MCMC) sampling and reversible jumps between models with different numbers of parameters are used to characterize the posterior distributions of the model parameters and the number of components per burst.

  6. 30 CFR 57.3461 - Rock bursts. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons to...

  7. Relative importance of pacing strategy and mean power output in 1500-m self-paced cycling

    NARCIS (Netherlands)

    Hettinga, F. J.; de Koning, J. J.; Hulleman, M.; Foster, C.

    Introduction Both mean power output (MPO) and the distribution of the available energy over the race, that is, pacing strategy, are critical factors in performance. The purpose of this study was to determine the relative importance of both pacing strategy and MPO to performance. Methods Six

  8. Antitachycardia pacing programming in implantable cardioverter defibrillator: A systematic review. (United States)

    De Maria, Elia; Giacopelli, Daniele; Borghi, Ambra; Modonesi, Letizia; Cappelli, Stefano


    Implantable cardioverter defibrillator (ICD) programming involves several parameters. In recent years antitachycardia pacing (ATP) has gained an increasing importance in the treatment of ventricular arrhythmias, whether slow or fast. It reduces the number of unnecessary and inappropriate shocks and improves both patient's quality of life and device longevity. There is no clear indication regarding the type of ATP to be used, except for the treatment of fast ventricular tachycardias (188 bpm-250 bpm) where it has been shown a greater efficacy and safety of burst compared to ramp; 8 impulses in each sequence of ATP appears to be the best programming option in this setting. Beyond ATP use, excellent clinical results were obtained with programming standardization following these principles: extended detection time in ventricular fibrillation (VF) zone; supraventricular discrimination criteria up to 200 bpm; first shock in VF zone at the maximum energy in order to reduce the risk of multiple shocks. The MADIT-RIT trial and some observational registries have also recently demonstrated that programming with a widespread use of ATP, higher cut-off rates or delayed intervention reduces the number of inappropriate and unnecessary therapies and improves the survival of patients during mid-term follow-up.

  9. Update on arrhythmias and cardiac pacing 2013. (United States)

    Almendral, Jesús; Pombo, Marta; Martínez-Alday, Jesús; González-Rebollo, José M; Rodríguez-Font, Enrique; Martínez-Ferrer, José; Castellanos, Eduardo; García-Fernández, F Javier; Ruiz-Mateas, Francisco


    This report discusses a selection of the most relevant articles on cardiac arrhythmias and pacing published in 2013. The first section discusses arrhythmias, classified as regular paroxysmal supraventricular tachyarrhythmias, atrial fibrillation, and ventricular arrhythmias, together with their treatment by means of an implantable cardioverter defibrillator. The next section reviews cardiac pacing, subdivided into resynchronization therapy, remote monitoring of implantable devices, and pacemakers. The final section discusses syncope. Copyright © 2013 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  10. Burst Suppression for ICP Control. (United States)

    Zeiler, Frederick A; Akoth, Eva; Gillman, Lawrence M; West, Michael


    The goal of our study was to perform a systematic review of the literature to determine the effect that burst suppression has on intracranial pressure (ICP) control. All articles from MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library, the International Clinical Trials Registry Platform (inception to January 2015), reference lists of relevant articles, and gray literature were searched. The strength of evidence was adjudicated using both the Oxford and the Grading of Recommendation Assessment Development and Education (GRADE) methodology. Seven articles were considered for review. A total of 108 patients were studied, all receiving burst suppression therapy. Two studies failed to document a decrease in ICP with burst suppression therapy. There were reports of severe hypotension and increased infection rates with barbiturate-based therapy. Etomidate-based suppressive therapy was linked to severe renal dysfunction. There currently exists both Oxford level 2b and GRADE C evidence to support that achieving burst suppression reduces ICP, and also has no effect on ICP, in severe traumatic brain injury. The literature suggests burst suppression therapy may be useful for ICP reduction in certain cases, although these situations are currently unclear. In addition, the impact on patient functional outcome is unclear. Further prospective study is warranted.

  11. How do we perceive activity pacing in rheumatology care?

    DEFF Research Database (Denmark)

    Cuperus, N.; Vliet Vlieland, T.; Brodin, N.


    Background: Activity pacing is a recommended non-pharmacological intervention for the management of rheumatic and musculoskeletal diseases in international clinical guidelines. In clinical practice, activity pacing aims at adapting daily activities, and is often an important component of self......-management programs. However, despite its wide endorsement in clinical practice, to date activity pacing is still a poorly understood concept. Objectives: To achieve consensus by means of an international Delphi exercise on the most important aspects of activity pacing as an intervention within non...... goals of activity pacing, behaviours of activity pacing (the actions people take to meet the goal of activity pacing), strategies to change behaviour in activity pacing (for example goal setting) and contextual factors that should be acknowledged when instructing activity pacing. Besides, topics...

  12. Potenzielle Einflussfaktoren auf Pacing im ausdauersportlichen Wettkampf

    NARCIS (Netherlands)

    Thiel, C.; de Koning, J.J.; Foster, C.


    In competitive endurance sport, athletes permanently regulate their performance to achieve the best result without threatening organismic integrity. This conscious and subconscious allocation of energy reserves in relation to an endpoint is termed pacing and depends on sport-specific experience as

  13. Self-Paced Instruction: Hello, Education (United States)

    Leuba, Richard J.; Flammer, Gordon H.


    Answers criticisms of self-paced instruction (SPI) by citing advantages of SPI over lecture methods. Concludes that criticisms of SPI are useful since they indicate in which areas further research should be conducted to improve this method of instruction. (MLH)

  14. The pace and shape of ageing

    DEFF Research Database (Denmark)

    Baudisch, Annette


    exhibits negligible ageing - contrary to the commonly held view that long-lived species are good candidates for negligible ageing. 5.Analysis of species in pace-shape space provides a tool to identify key determinants of the evolution of ageing for species across the tree of life....

  15. FERMIGBRST - Fermi GBM Burst Catalog (United States)

    National Aeronautics and Space Administration — This table lists all of the triggers observed by a subset of the 14 GBM detectors (12 NaI and 2 BGO) which have been classified as gamma-ray bursts (GRBs). Note that...

  16. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    This suggests either larger bulk Lorentz factors or spatially closer locations for the short GRBs [13]. From luminosity function studies, the local space density of the short GRBs is likely to be lower than that of the long ones by a factor of ~3 [14]. While analysing time tagged event (TTE) data for 156 category A type bursts.

  17. Cosmological Time Dilation in Gamma Ray Bursts?


    Band, David


    Norris et al. (1994) report that the temporal structure of faint gamma ray bursts is longer than that of bright bursts, as expected for time dilation in the cosmological models of burst origin. I show that the observed trends can easily be produced by a burst luminosity function and thus may not result from cosmological effects. A cosmological signature may be present, but the tests Norris et al. present are not powerful enough to detect these signatures.

  18. Fine structure in fast drift storm bursts

    International Nuclear Information System (INIS)

    McConnell, D.; Ellis, G.R.A.


    Recent observations with high time resolution of fast drift storm (FDS) solar bursts are described. A new variety of FDS bursts characterised by intensity maxima regularly placed in the frequency domain is reported. Possible interpretations of this are mentioned and the implications of the short duration of FDS bursts are discussed. (orig.)

  19. Temporary emergency pacing-an orphan in district hospitals

    DEFF Research Database (Denmark)

    Gjesdal, Knut; Johansen, Jens Brock; Gadler, Fredrik


    This editorial discusses a report on the 1 year experience with temporary pacing, especially in the emergency setting, in several Norwegian district hospitals. The vast majority of the patients received transvenous temporary pacing, and the majority of leads were placed by noncardiologists. The p...... to a hospital with more available competence. Ideally, those who need pacing immediately, including those who need permanent pacing, should be offered permanent implantation on a 24 hours/7 days per week base....

  20. Pace of work stabilising, but not in all sectors

    NARCIS (Netherlands)

    Houtman, I.L.D.


    The Netherlands had the highest level of work pace in Europe but this position has levelled off in the last five years. There appears to be a general trend towards a decline in work pace. However, different sectors show varying trends, with work pace on the rise again in the education, health and

  1. Visual aided pacing in respiratory maneuvers

    International Nuclear Information System (INIS)

    Rambaudi, L R; Rossi, E; Mantaras, M C; Perrone, M S; Siri, L Nicola


    A visual aid to pace self-controlled respiratory cycles in humans is presented. Respiratory manoeuvres need to be accomplished in several clinic and research procedures, among others, the studies on Heart Rate Variability. Free running respiration turns to be difficult to correlate with other physiologic variables. Because of this fact, voluntary self-control is asked from the individuals under study. Currently, an acoustic metronome is used to pace respiratory frequency, its main limitation being the impossibility to induce predetermined timing in the stages within the respiratory cycle. In the present work, visual driven self-control was provided, with separate timing for the four stages of a normal respiratory cycle. This visual metronome (ViMet) was based on a microcontroller which power-ON and -OFF an eight-LED bar, in a four-stage respiratory cycle time series handset by the operator. The precise timing is also exhibited on an alphanumeric display

  2. Phrenic pacing compared with mechanical ventilation

    DEFF Research Database (Denmark)

    Andersen, Morten Packert; Laub, Michael; Biering-Sørensen, Fin


    STUDY DESIGN: Comparable case series. OBJECTIVES: High-cervical spinal cord injury (SCI) may disrupt the ability to breathe sufficiently. To restore respiration a phrenic nerve pacer can be implanted. The aims of this study were to describe the use of phrenic nerve pacing in tetraplegics in Denmark...... mechanical ventilator dependent tetraplegics met the inclusion criteria. Data were retrieved from medical records and a structured follow-up interview with seven individuals from each group. RESULTS: No significant differences were found when comparing age at injury, time since injury, length...... of hospitalization, incidence of pneumonia, number of pneumonia hospitalizations, number of tracheal suctions, speech quality and activities of daily living or quality of life. On the Short Form Health Survey (SF36) mental health summary the median for both users of phrenic nerve pacing and users of mechanical...

  3. Reproducibility of pacing profiles in elite swimmers. (United States)

    Skorski, Sabrina; Faude, Oliver; Caviezel, Seraina; Meyer, Tim


    To analyze the reproducibility of pacing in elite swimmers during competitions and to compare heats and finals within 1 event. Finals and heats of 158 male swimmers (age 22.8 ± 2.9 y) from 29 nations were analyzed in 2 competitions (downloaded from Of these, 134 were listed in the world's top 50 in 2010; the remaining 24 were finalists of the Pan Pacific Games or European Championships. The level of both competitions for the analysis had to be at least national championships (7.7 ± 5.4 wk apart). Standard error of measurement expressed as percentage of the subject's mean score (CV) with 90% confidence limits (CL) for each 50-m split time and for total times were calculated. In addition, mixed general modeling was used to determine standard deviations between and within swimmers. CV for total time in finals ranged between 0.8% and 1.3% (CL 0.6-2.2%). Regarding split times, 200-m freestyle showed a consistent pacing over all split times (CV 0.9-1.6%). During butterfly, backstroke, and 400-m freestyle, CVs were low in the first 3 and 7 sections, respectively (CV 0.9-1.7%), with greater variability in the last section (1.9-2.2%). In breaststroke, values were higher in all sections (CV 1.2-2.3%). Within-subject SDs for changes between laps were between 0.9% and 2.6% in all finals. Split-time variability for finals and heats ranged between 0.9% and 2.5% (CL 0.3-4.9%). Pacing profiles are consistent between different competitions. Variability of pacing seems to be a result of the within-subject variation rather than a result of different competitions.

  4. The Platform-Aware Compilation Environment (PACE) (United States)


    HPCToolkit. PACE Compiler: • AAP: The code for the AAP is built on top of the open -source Xerces XML parser and the standard GNU utilities Bison and...Microsystems Technology Office (DARPA/MTO) 675 North Randolph Street Arlington, VA 22203‐2114 10. SPONSORING/MONITORING AGENCY ACRONYM...can be mapped efficiently onto the system’s hardware. To achieve a reasonably high fraction of available performance with existing tools, the

  5. Cardiac pacing in heart failure patients with left bundle branch block: impact of pacing site for optimizing left ventricular resynchronization. (United States)

    Pappone, C; Rosanio, S; Oreto, G; Tocchi, M; Gulletta, S; Salvati, A; Dicandia, C; Santinelli, V; Mazzone, P; Veglia, F; Ding, J; Sallusti, L; Spinelli, J; Vicedomini, G


    Acute left ventricular pacing has been associated with hemodynamic improvement in patients with congestive heart failure and wide QRS complex. We hypothesized that pacing two left ventricular sites simultaneously would produce faster activation and better systolic function than single-site pacing. We selected 14 heart failure patients (NYHA functional class III or IV) in normal sinus rhythm with left bundle branch block and QRS > 150 ms. An 8F dual micromanometer catheter was placed in the aorta for measuring +dP/dt (mmHg/s), aortic pulse pressure (mmHg), and end-diastolic pressure (mmHg). Pacing leads were positioned via coronary veins at the posterior base and lateral wall. Patients were acutely paced VDD at the posterior base, lateral wall, and both sites (dual-site) with 5 atrioventricular delays (from 8 ms to PR -30 ms). Pacing sequences were executed in randomized order using a custom external computer (FlexStim, Guidant CRM). Dual-site pacing increased peak +dP/dt significantly more than posterior base and lateral wall pacing. Dual-site and posterior base pacing raised aortic pulse pressure significantly more than lateral wall pacing. Dual-site pacing shortened QRS duration by 22 %, whereas posterior base and lateral wall pacing increased it by 2 and 12%, respectively (p = 0.006). In heart failure patients with left bundle branch block, dual-site pacing improves systolic function more than single-site stimulation. Improved ventricular activation synchrony, expressed by paced QRS narrowing, may account for the additional benefit of dual- vs single-site pacing in enhancing contractility. This novel approach deserves consideration for future heart failure pacing studies.

  6. Leadless Pacing: Current State and Future Direction. (United States)

    Merkel, Matthias; Grotherr, Philipp; Radzewitz, Andrea; Schmitt, Claus


    Leadless pacing is now an established alternative to conventional pacing with subcutaneous pocket and transvenous lead for patients with class I or II single-chamber pacing indication. Available 12-month follow-up data shows a 48% fewer major complication rate in patients with Micra™ compared to a historical control group in a nonrandomized study [1]. There is one system with Food and Drug Administration (FDA) approval and two with the Communauté Européenne (CE) mark. The OPS code for the implantation is 8-83d.3 and the procedure has recently been rated as a "new Examination and Treatment Method (NUB)" in the German DRG system, meaning adequate reimbursement is negotiable with health insurance providers. The systems offer similar generator longevity and programming possibilities as conventional pacemaker systems, including rate response, remote monitoring, and MRI safety. The biggest downsides to date are limitations to single-chamber stimulation, lack of long-time data, and concerns of handling of the system at the end of its life span. However, implant procedure complication rates and procedure times do not exceed conventional pacemaker operations, and proper training and patient selection is provided.

  7. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    The spectral lag τl for a burst was estimated by taking the difference between time centroids obtained using arrival instants (from TTE data) corresponding to photon energies larger than 100 keV, and to energies less than 100 keV so that τl ≡ τ > 100 keV − τ < 100 keV. (1). The time centroid for an energy channel is given by.

  8. On the neutron bursts origin.

    CERN Document Server

    Stenkin, Yu V


    The origin of the neutron bursts in Extensive Air Showers (EAS) is explained using results of the experiments and CORSIKA based Monte-Carlo simulations. It is shown that events with very high neutron multiplicity observed last years in neutron monitors as well as in surrounding detectors, are caused by usual EAS core with primary energies > 1 PeV. No exotic processes were needed for the explanation.

  9. NICER Eyes on Bursting Stars (United States)

    Kohler, Susanna


    What happens to a neutron stars accretion disk when its surface briefly explodes? A new instrument recently deployed at the International Space Station (ISS) is now watching bursts from neutron stars and reporting back.Deploying a New X-Ray MissionLaunch of NICER aboard a Falcon 9 rocket in June 2017. [NASA/Tony Gray]In early June of 2017, a SpaceX Dragon capsule on a Falcon 9 rocket launched on a resupply mission to the ISS. The pressurized interior of the Dragon contained the usual manifest of crew supplies, spacewalk equipment, and vehicle hardware. But the unpressurized trunk of the capsule held something a little different: the Neutron star Interior Composition Explorer (NICER).In the two weeks following launch, NICER was extracted from the SpaceX Dragon capsule and installed on the ISS. And by the end of the month, the instrument was already collecting its first data set: observations of a bright X-ray burst from Aql X-1, a neutron star accreting matter from a low-mass binary companion.Impact of BurstsNICERs goal is to provide a new view of neutron-star physics at X-ray energies of 0.212 keV a window that allows us to explore bursts of energy that neutron stars sometimes emit from their surfaces.Artists impression of an X-ray binary, in which a compact object accretes material from a companion star. [ESA/NASA/Felix Mirabel]In X-ray burster systems, hydrogen- and helium-rich material from a low-mass companion star piles up in an accretion disk around the neutron star. This material slowly funnels onto the neutron stars surface, forming a layer that gravitationally compresses and eventually becomes so dense and hot that runaway nuclear fusion ignites.Within seconds, the layer of material is burned up, producing a burst of emission from the neutron star that outshines even the inner regions of the hot accretion disk. Then more material funnels onto the neutron star and the process begins again.Though we have a good picture of the physics that causes these bursts

  10. Bubble bursting at an interface (United States)

    Kulkarni, Varun; Sajjad, Kumayl; Anand, Sushant; Fezzaa, Kamel


    Bubble bursting is crucial to understanding the life span of bubbles at an interface and more importantly the nature of interaction between the bulk liquid and the outside environment from the point of view of chemical and biological material transport. The dynamics of the bubble as it rises from inside the liquid bulk to its disappearance on the interface after bursting is an intriguing process, many aspects of which are still being explored. In our study, we make detailed high speed imaging measurements to examine carefully the hole initiation and growth in bursting bubbles that unearth some interesting features of the process. Previous analyses available in literature are revisited based on our novel experimental visualizations. Using a combination of experiments and theory we investigate the role of various forces during the rupturing process. This work aims to further our current knowledge of bubble dynamics at an interface with an aim of predicting better the bubble evolution from its growth to its eventual integration with the liquid bulk.

  11. Impact of pacing modality and biventricular pacing on cardiac output and coronary conduit flow in the post-cardiotomy patient.

    LENUS (Irish Health Repository)

    Healy, David G


    We have previously demonstrated the role of univentricular pacing modalities in influencing coronary conduit flow in the immediate post-operative period in the cardiac surgery patient. We wanted to determine the mechanism of this improved coronary conduit and, in addition, to explore the possible benefits with biventricular pacing. Sixteen patients undergoing first time elective coronary artery bypass grafting who required pacing following surgery were recruited. Comparison of cardiac output and coronary conduit flow was performed between VVI and DDD pacing with a single right ventricular lead and biventricular pacing lead placement. Cardiac output was measured using arterial pulse waveform analysis while conduit flow was measured using ultrasonic transit time methodology. Cardiac output was greatest with DDD pacing using right ventricular lead placement only [DDD-univentricular 5.42 l (0.7), DDD-biventricular 5.33 l (0.8), VVI-univentricular 4.71 l (0.8), VVI-biventricular 4.68 l (0.6)]. DDD-univentricular pacing was significantly better than VVI-univentricular (P=0.023) and VVI-biventricular pacing (P=0.001) but there was no significant advantage to DDD-biventricular pacing (P=0.45). In relation to coronary conduit flow, DDD pacing again had the highest flow [DDD-univentricular 55 ml\\/min (24), DDD-biventricular 52 ml\\/min (25), VVI-univentricular 47 ml\\/min (23), VVI-biventricular 50 ml\\/min (26)]. DDD-univentricular pacing was significantly better than VVI-univentricular (P=0.006) pacing but not significantly different to VVI-biventricular pacing (P=0.109) or DDD-biventricular pacing (P=0.171). Pacing with a DDD modality offers the optimal coronary conduit flow by maximising cardiac output. Biventricular lead placement offered no significant benefit to coronary conduit flow or cardiac output.

  12. Fuzzy-Based Adaptive Hybrid Burst Assembly Technique for Optical Burst Switched Networks

    Directory of Open Access Journals (Sweden)

    Abubakar Muhammad Umaru


    Full Text Available The optical burst switching (OBS paradigm is perceived as an intermediate switching technology for future all-optical networks. Burst assembly that is the first process in OBS is the focus of this paper. In this paper, an intelligent hybrid burst assembly algorithm that is based on fuzzy logic is proposed. The new algorithm is evaluated against the traditional hybrid burst assembly algorithm and the fuzzy adaptive threshold (FAT burst assembly algorithm via simulation. Simulation results show that the proposed algorithm outperforms the hybrid and the FAT algorithms in terms of burst end-to-end delay, packet end-to-end delay, and packet loss ratio.

  13. Hardness/intensity correlations among BATSE bursts (United States)

    Paciesas, William S.; Pendleton, Geoffrey N.; Kouveliotou, Chryssa; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.


    Conclusions about the nature of gamma-ray bursts derived from the size-frequency distribution may be altered if a significant correlation exists between burst intensity and spectral shape. Moreover, if gamma-ray bursts have a cosmological origin, such a correlation may be expected to result from the expansion of the universe. We have performed a rudimentary search of the BATSE bursts for hardness/intensity correlations. The range of spectral shapes was determined for each burst by computing the ratio of the intensity in the range 100-300 keV to that in 55-300 keV. We find weak evidence for the existence of a correlation, the strongest effect being present when comparing the maximum hardness ratio for each burst with its maximum rate.

  14. Swift Burst Alert Telescope (BAT) Instrument Response

    International Nuclear Information System (INIS)

    Parsons, A.; Barthelmy, S.; Cummings, J.; Gehrels, N.; Hullinger, D.; Krimm, H.; Markwardt, C.; Tueller, J.; Fenimore, E.; Palmer, D.; Sato, G.; Takahashi, T.; Nakazawa, K.; Okada, Y.; Takahashi, H.; Suzuki, M.; Tashiro, M.


    The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field-of-view (FOV), provides the gamma-ray burst triggers and locations for the Swift Gamma-Ray Burst Explorer. In addition to providing this imaging information, BAT will perform a 15 keV - 150 keV all-sky hard x-ray survey based on the serendipitous pointings resulting from the study of gamma-ray bursts, and will also monitor the sky for transient hard x-ray sources. For BAT to provide spectral and photometric information for the gamma-ray bursts, the transient sources and the all-sky survey, the BAT instrument response must be determined to an increasingly greater accuracy. This paper describes the spectral models and the ground calibration experiments used to determine the BAT response to an accuracy suitable for gamma-ray burst studies

  15. A Gamma-Ray Burst Trigger Toolkit (United States)

    Band, David L.; White, Nicholas E. (Technical Monitor)


    The detection rate of a gamma-ray burst detector can be increased by using a count rate trigger with many accumulation times DELTAt and energy bands DELTAE Because a burst's peak flux varies when averaged over different DELTAt and DELTAE the nominal sensitivity (the numerical value of the peak flux) of a trigger system is less important than how much fainter a burst could be at the detection threshold as DELTAt and DELTAE are changed. The relative sensitivity of different triggers can be quantified by referencing the detection threshold back to the peak flux for a fiducial value of DELTAt and DELTA E. This mapping between peak flux values for different sets of DELTAt and DELTAE varies from burst to burst. Quantitative estimates of the burst detection rate for a given detector and trigger system can be based on the observed rate at a measured peak flux value in this fiducial trigger. Predictions of a proposed trigger's burst detection rate depend on the assumed burst population, and these predictions can be wildly in error for triggers that differ significantly from previous missions. I base the fiducial rate on the BATSE observations: 550 bursts per sky above a peak flux of 0.3 ph per square centimeter per second averaged over DELTAt=1.024 sec and DELTAE=50-300 keV. Using a sample of 100 burst lightcurves I find that triggering on any value of DELTAt that is a multiple of 0.064 sec decreases the average threshold peak flux on the 1.024 sec timescale by a factor of 0.6. Extending DELTAE to lower energies includes the large flux of the X-ray background, increasing the background count rate. Consequently a low energy DELTAE is advantageous only for very soft bursts. Whether a large fraction of the population of bright bursts is soft is disputed; the new population of X-ray Flashes is soft but relatively faint.

  16. Helium bubble bursting in tungsten

    International Nuclear Information System (INIS)

    Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.


    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz

  17. Chaotic bursting in semiconductor lasers (United States)

    Ruschel, Stefan; Yanchuk, Serhiy


    We investigate the dynamic mechanisms for low frequency fluctuations in semiconductor lasers subjected to delayed optical feedback, using the Lang-Kobayashi model. This system of delay differential equations displays pronounced envelope dynamics, ranging from erratic, so called low frequency fluctuations to regular pulse packages, if the time scales of fast oscillations and envelope dynamics are well separated. We investigate the parameter regions where low frequency fluctuations occur and compute their Lyapunov spectra. Using the geometric singular perturbation theory, we study this intermittent chaotic behavior and characterize these solutions as bursting slow-fast oscillations.

  18. Cosmology from gamma ray bursts

    International Nuclear Information System (INIS)

    Pouri, Athina; Basilakos, Spyros


    In this study we propose to use Gamma Ray Bursts (GRBs) as standard candles in order to constrain the expansion history of the universe up to redshifts of z ∼ 6. In particular, we utilize the 69 GRB dataset recently compiled by Cardone et al. (2009). Performing a joint likelihood analysis of the recent supernovae type Ia (SNIa) data and the GRBs we can put constraints on the main cosmological parameters (Ω m , w). However, the use of the current GRBs to trace the Hubble relation, as an alternative to the traditionally used SNIa, can not break the degeneracy between the Ω m and the dark energy equation of state parameter.

  19. Ballerina - pirouettes in search of gamma bursts

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik


    The cosmological origin of gamma ray bursts has now been established with reasonable certainty, Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are propo......The cosmological origin of gamma ray bursts has now been established with reasonable certainty, Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We...

  20. Interatrial septum pacing decreases atrial dyssynchrony on strain rate imaging compared with right atrial appendage pacing. (United States)

    Yasuoka, Yoshinori; Abe, Haruhiko; Umekawa, Seiko; Katsuki, Keiko; Tanaka, Norio; Araki, Ryo; Imanaka, Takahiro; Matsutera, Ryo; Morisawa, Daisuke; Kitada, Hirokazu; Hattori, Susumu; Noda, Yoshiki; Adachi, Hidenori; Sasaki, Tatsuya; Miyatake, Kunio


    Interatrial septum pacing (IAS-P) decreases atrial conduction delay compared with right atrial appendage pacing (RAA-P). We evaluate the atrial contraction with strain rate of tissue Doppler imaging (TDI) during sinus activation or with IAS-P or RAA-P. Fifty-two patients with permanent pacemaker for sinus node disease were enrolled in the study. Twenty-three subjects were with IAS-P and 29 with RAA-P. The time from end-diastole to peak end-diastolic strain rate was measured and corrected with RR interval on electrocardiogram. It was defined as the time from end-diastole to peak end-diastolic strain rate (TSRc), and the balance between maximum and minimum TSRc at three sites (ΔTSRc) was compared during sinus activation and with pacing rhythm in each group. There were no significant differences observed in general characteristics and standard echocardiographic parameters except the duration of pacing P wave between the two groups. The duration was significantly shorter in the IAS-P group compared with the RAA-P group (95 ± 34 vs 138 ± 41; P = 0.001). TSRc was significantly different between sinus activation and pacing rhythm (36.3 ± 35.7 vs 61.6 ± 36.3; P = 0.003) in the RAA-P group, whereas no significant differences were observed in the IAS-P group (25.4 ± 12.1 vs 27.7 ± 14.7; NS). During the follow-up (mean 2.4 ± 0.7 years), the incidence of paroxysmal atrial fibrillation (AF) conversion to permanent AF was not significantly different between the two groups. IAS-P decreased the contraction delay on atrial TDI compared to RAA-P; however, it did not contribute to the reduction of AF incidence in the present study. ©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.

  1. Noninvasive external cardiac pacing for thallium-201 scintigraphy

    International Nuclear Information System (INIS)

    Feldman, M.D.; Warren, S.E.; Gervino, E.V.


    Improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and tolerable patient discomfort. To assess the use of this modality of pacing in combination with thallium scintigraphy as a noninvasive pacing stress test, we applied simultaneous noninvasive cardiac pacing, hemodynamic monitoring, and thallium-201 scintigraphy in 14 patients undergoing cardiac catheterization for chest pain syndromes. Two patients had normal coronary arteries, while the remaining 12 had significant coronary artery disease. Thallium scintigraphic responses to pacing were compared to routine exercise thallium stress testing in nine of these 14 patients. All patients were noninvasively paced to more than 85% of the age-predicted maximum heart rate. Twelve patients demonstrated reversible thallium defects, which corresponded in 11 cases to significant lesions seen on coronary angiography. Of nine patients who underwent both pacing and exercise thallium stress tests, comparable maximal rate-pressure products were achieved. Moreover, thallium imaging at peak pacing and during delayed views did not differ significantly from exercise thallium scintigraphy. A limiting factor associated with the technique was local patient discomfort, which occurred to some degree in all patients. We conclude that noninvasive external cardiac pacing together with thallium scintigraphy is capable of detecting significant coronary artery disease and may be comparable to routine exercise thallium stress testing. This new modality of stress testing could be useful in patients unable to undergo the exercise required for standard exercise tolerance testing, particularly if improvements in the technology can be found to reduce further the local discomfort

  2. Hibernia field construction pace picks up speed

    International Nuclear Information System (INIS)



    This paper reports that the pace of construction is increasing for the $5.2 billion (Canadian) Hibernia oil field development project off Newfoundland with a new partner close to signing on. Texaco, Inc. is reported ready to pick up a 25% interest in the project within a month. Construction activity for offshore systems was cut 50% last February when Gulf Canada Resources Inc. The it planned to withdraw from its 25% interest in Hibernia. Since then, remaining interest owners Mobil Oil Canada Ltd., Chevron Canada Resources Ltd., and Petro-Canada have been seeking new partners. The effort has focused on Texaco with Canadian Energy Minister Jake Epp playing a role in talks. Hibernia's construction work force has risen to 850 from a low of 600. A spokesman for Hibernia Management and Development Co., project manager, the a steady increase in the work force is planned

  3. Ginga Gamma-Ray Burst Line Occurrence (United States)

    Band, David


    The purpose of this project is the statistical evaluation of the occurrence of spectral lines in the gamma-ray burst spectra detected by the Ginga burst detector, and the comparison of the Ginga results to the BATSE observations. Two significant line features were detected in the Ginga bursts, but thus far none have been detected in the bursts BATSE detected. These line features may indicate the presence of strong magnetic fields in bursts, and therefore are important physical diagnostics of the conditions in the plasma which radiates the observed gamma-rays. The issue is whether there is a discrepancy between the Ginga and BATSE results; the potential discrepancy must be evaluated statistically. Even if BATSE line detections are announced, the statistical methodology we have developed can be used to estimate the rate at which different types of spectral features occur.

  4. Burst suppression probability algorithms: state-space methods for tracking EEG burst suppression (United States)

    Chemali, Jessica; Ching, ShiNung; Purdon, Patrick L.; Solt, Ken; Brown, Emery N.


    Objective. Burst suppression is an electroencephalogram pattern in which bursts of electrical activity alternate with an isoelectric state. This pattern is commonly seen in states of severely reduced brain activity such as profound general anesthesia, anoxic brain injuries, hypothermia and certain developmental disorders. Devising accurate, reliable ways to quantify burst suppression is an important clinical and research problem. Although thresholding and segmentation algorithms readily identify burst suppression periods, analysis algorithms require long intervals of data to characterize burst suppression at a given time and provide no framework for statistical inference. Approach. We introduce the concept of the burst suppression probability (BSP) to define the brain's instantaneous propensity of being in the suppressed state. To conduct dynamic analyses of burst suppression we propose a state-space model in which the observation process is a binomial model and the state equation is a Gaussian random walk. We estimate the model using an approximate expectation maximization algorithm and illustrate its application in the analysis of rodent burst suppression recordings under general anesthesia and a patient during induction of controlled hypothermia. Main result. The BSP algorithms track burst suppression on a second-to-second time scale, and make possible formal statistical comparisons of burst suppression at different times. Significance. The state-space approach suggests a principled and informative way to analyze burst suppression that can be used to monitor, and eventually to control, the brain states of patients in the operating room and in the intensive care unit.

  5. Failed anti-tachycardia pacing can be used to differentiate atrial arrhythmias from ventricular tachycardia in implantable cardioverter-defibrillators. (United States)

    Michael, Kevin A; Enriquez, Andres; Baranchuk, Adrian; Haley, Charlotte; Caldwell, Jane; Simpson, Christopher S; Abdollah, Hoshiar; Redfearn, Damian P


    Atrial fibrillation/tachycardia (AF/AT) may result in inappropriate therapies in implantable cardioverter-defibrillators (ICDs). The post-pacing interval (PPI) and tachycardia cycle length difference (PPI - TCL) has been previously demonstrated to indicate the proximity of the pacing site to a tachycardia origin. We postulated that the PPI and PPI - TCL would be greater in AT/AF vs. ventricular tachycardia (VT) after episodes of failed anti-tachycardia pacing (ATP). This was a single-centre, retrospective study evaluating consecutive patients implanted with dual (DR)/biventricular (BIV) ICDs. Stored electrograms were used to determine whether the ATP captured the arrhythmia and the arrhythmia did not present with primary or secondary termination. Measurements were done using manual calipers. A total of 155 patients were included. There were 79 BIV and 76 DR devices. In total, 39 episodes were identified in 20 patients over a 23-month follow-up period. A total of 76 sequences of ATP (burst/ramp) were delivered, 28 (37%) of them inappropriate. Fifty-one events (18 AT/AF and 33 VT) were compared. The mean PPI was 693 ± 96 vs. 512 ± 88 ms (P failed ATP differs significantly between AF/AT and VT and are therefore useful indices to discriminate between supraventricular tachycardia and VT in ICDs. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email:

  6. Wind cooling during a self-paced cycling time trial

    NARCIS (Netherlands)

    Teunissen, L.P.J.; de Haan, A.; de Koning, J.J.; Daanen, H.A.M.


    Introduction Wind has been shown to be an effective cooling method during fixed-paced exercise in the heat, decreasing thermal strain and increasing time to fatigue. However, it has been scarcely investigated in what way these observations translate to self-paced performance. So the aim of this

  7. 77 FR 3958 - Mortgage Assets Affected by PACE Programs (United States)


    ... collateral, and such liens ``run'' with the property. As a result, a mortgagee foreclosing on a property... (``ANPR'') concerning mortgage assets affected by Property Assessed Clean Energy (``PACE'') programs and... February 28, 2011, that deal with property assessed clean energy (PACE) programs.'' In response to and...

  8. Prediction of Procrastination in a Self-Pacing Instructional System. (United States)

    Ely, Donald D.; Hampton, John D.

    The objective of the study was to predict potential procrastinators in a self-pacing instructional system. Seventy-five entering college freshmen were randomly selected to participate in a large scale individually-paced program. Those students (25) who procrastinated were classified as "no-start-procrastinators" (NSP); the remainder (52) were…

  9. PACE3 - front-end chip for the CMS Preshower

    CERN Multimedia

    Aspel, Paul


    This is PACE3 which is the front-end chip for the CMS Preshower. In fact PACE3 is the combination of two ASICs called Delta3 and PACEAM3. Delta3 is on the left and PACEAM3 is on the right. The two ASICs are bonded together and then packaged within a single 196 pin fpBGA package.

  10. Social Interaction in Self-Paced Distance Education (United States)

    Anderson, Terry; Upton, Lorne; Dron, Jon; Malone, Judi; Poelhuber, Bruno


    In this paper we present a case study of a self-paced university course that was originally designed to support independent, self-paced study at distance. We developed a social media intervention, in design-based research terms, that allows these independent students to contribute archived content to enhance the course, to engage in discussions…

  11. A comparison of single-lead atrial pacing with dual-chamber pacing in sick sinus syndrome

    DEFF Research Database (Denmark)

    Nielsen, Jens Cosedis; Thomsen, Poul Erik B; Højberg, Søren


    In patients with sick sinus syndrome, bradycardia can be treated with a single-lead pacemaker or a dual-chamber pacemaker. Previous trials have revealed that pacing modes preserving atrio-ventricular synchrony are superior to single-lead ventricular pacing, but it remains unclear if there is any...

  12. Spectral evolution of gamma-ray bursts (United States)

    Band, D.; Matteson, J.; Ford, L.; Schaefer, B.; Teegarden, B.; Cline, T.; Paciesas, W.; Pendleton, G.; Fishman, G.; Meegan, C.


    BATSE's Spectral Detectors provide a series of high resolution spectra over the duration of a gamma-ray burst; fits to these spectra show the evolution of the continuum as the burst progresses. The burst continuum can usually be fit by the spectral form AE sup alpha exp(-E/kT) from around 25 keV to more than 3 MeV, with varying trends in the value and evolution of the spectral parameters. As a result of limited statistics for E greater than 1 - 2 MeV in the individual spectra, a high energy power law is not required. Only long duration strong bursts can be studied by fitting a series of spectra, and therefore our conclusions concern only this class of burst. The bursts we analyzed tend to be characterized by a hard-to-soft trend both for individual intensity spikes and for the burst as a whole: the hardness leads the count rate in spectra which resolve the temporal variations, while the hardness of successive spikes decreases. We also summarize the performance of the Spectral Detectors and the development of analysis tools to date.

  13. Gamma-Ray Bursts Have Millisecond Variability

    International Nuclear Information System (INIS)

    Walker, Katharine C.; Schaefer, Bradley E.; Fenimore, E. E.


    We have performed searches for isolated flares and for steady flickering in the initial ∼1 s of gamma-ray burst light curves on the microsecond to millisecond timescales. Two bursts among our sample of 20 revealed four isolated flares with timescales from 256 to 2048 μs. A wavelet analysis for our sample showed low-level flickering for all bursts on timescales from 256 μs to 33 ms, with the majority of bursts containing rise times faster than 4 ms and 30% having rise times faster than 1 ms. These results show that millisecond variability is common in classical bursts and not some exceptional activity by a possibly separate class of bursts. These fast rise times can be used to place the following severe limits on burst models. (1) The characteristic thickness of the energy generation region must be less than 1200 km along the line of sight. (2) The angular size of the gamma-ray emission region as subtended from the central source must be less than 42''. (3) The expanding ejecta must have a range of Lorentz factors along a radius line with a dispersion of less than roughly 2%. (4) Within the external shock scenario, the characteristic dimension of the impacted cloud must be smaller than 16 AU on average. (5) Within the collimated jet scenario, the collimation angle must be smaller than 42''. (c) 2000 The American Astronomical Society

  14. Bursting neurons and ultrasound avoidance in crickets

    Directory of Open Access Journals (Sweden)

    Gary eMarsat


    Full Text Available Decision making in invertebrates often relies on simple neural circuits composed of only a few identified neurons. The relative simplicity of these circuits makes it possible to identify the key computation and neural properties underlying decisions. In this review, we summarize recent research on the neural basis of ultrasound avoidance in crickets, a response that allows escape from echolocating bats. The key neural property shaping behavioral output is high-frequency bursting of an identified interneuron, AN2, which carries information about ultrasound stimuli from receptor neurons to the brain. AN2's spike train consists of clusters of spikes –bursts– that may be interspersed with isolated, non-burst spikes. AN2 firing is necessary and sufficient to trigger avoidance steering but only high-rate firing, such as occurs in bursts, evokes this response. AN2 bursts are therefore at the core of the computation involved in deciding whether or not to steer away from ultrasound. Bursts in AN2 are triggered by synaptic input from nearly synchronous bursts in ultrasound receptors. Thus the population response at the very first stage of sensory processing –the auditory receptor- already differentiates the features of the stimulus that will trigger a behavioral response from those that will not. Adaptation, both intrinsic to AN2 and within ultrasound receptors, scales the burst-generating features according to the stimulus statistics, thus filtering out background noise and ensuring that bursts occur selectively in response to salient peaks in ultrasound intensity. Furthermore AN2’s sensitivity to ultrasound varies adaptively with predation pressure, through both developmental and evolutionary mechanisms. We discuss how this key relationship between bursting and the triggering of avoidance behavior is also observed in other invertebrate systems such as the avoidance of looming visual stimuli in locusts or heat avoidance in beetles.

  15. Pushing the pace of tree species migration.

    Directory of Open Access Journals (Sweden)

    Eli D Lazarus

    Full Text Available Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale.

  16. A section of a pacing mine timbering

    Energy Technology Data Exchange (ETDEWEB)

    Hodous, J.; Kubac, J.; Novak, Z.; Skrobalek, J.; Zajic, K.


    A section is proposed for a pacing mine support of the wall and supporting type, designed for reinforcing the operational space of a longwall. The support section differs from the known in that it has relatively large mobility with the use of single stage telescopic hydraulic uprights. The section has left and right skiis, to which the tunneling machine with an upper part is attached using a hinged link. One hydraulic upright is installed on each ski, while a device for advancing the support is installed between the skiis. It is linked using a trough with the longwall conveyor which is not shown in the figure. A complex shaped track is made on each ski with three support recesses located at a different height relative to the base of the ski. The hydraulic upright is linked by its fixed part with the upper part of with the heading machine. The support has controllable projections on two sides, each of which is inserted in a track. Moreover, the support is attached to a hydraulic power cylinder, which is hinged with one of the skiis.

  17. The pace of aging: Intrinsic time scales in demography

    Directory of Open Access Journals (Sweden)

    Tomasz Wrycza


    Full Text Available Background: The pace of aging is a concept that captures the time-related aspect of aging. It formalizesthe idea of a characteristic life span or intrinsic population time scale. In the rapidly developing field of comparative biodemography, measures that account for inter-speciesdifferences in life span are needed to compare how species age. Objective: We aim to provide a mathematical foundation for the concept of pace. We derive desiredmathematical properties of pace measures and suggest candidates which satisfy these properties. Subsequently, we introduce the concept of pace-standardization, which reveals differences in demographic quantities that are not due to pace. Examples and consequences are discussed. Conclusions: Mean life span (i.e., life expectancy from birth or from maturity is intuitively appealing,theoretically justified, and the most appropriate measure of pace. Pace-standardizationprovides a serviceable method for comparative aging studies to explore differences indemographic patterns of aging across species, and it may considerably alter conclusionsabout the strength of aging.

  18. The genesis of period-adding bursting without bursting-chaos in the Chay model

    International Nuclear Information System (INIS)

    Yang Zhuoqin; Lu Qishao; Li Li


    According to the period-adding firing patterns without chaos observed in neuronal experiments, the genesis of the period-adding 'fold/homoclinic' bursting sequence without bursting-chaos is explored by numerical simulation, fast/slow dynamics and bifurcation analysis of limit cycle in the neuronal Chay model. It is found that each periodic bursting, from period-1 to 7, is separately generated by the corresponding periodic spiking pattern through two period-doubling bifurcations, except for the period-1 bursting occurring via a Hopf bifurcation. Consequently, it can be revealed that this period-adding bursting bifurcation without chaos has a compound bifurcation structure with transitions from spiking to bursting, which is closely related to period-doubling bifurcations of periodic spiking in essence

  19. On Gamma-Ray Bursts

    CERN Document Server

    Ruffini, Remo; Bianco, Carlo Luciano; Caito, Letizia; Chardonnet, Pascal; Cherubini, Christian; Dainotti, Maria Giovanna; Fraschetti, Federico; Geralico, Andrea; Guida, Roberto; Patricelli, Barbara; Rotondo, Michael; Hernandez, Jorge Armando Rueda; Vereshchagin, Gregory; Xue, She-Sheng


    (Shortened) We show by example how the uncoding of Gamma-Ray Bursts (GRBs) offers unprecedented possibilities to foster new knowledge in fundamental physics and in astrophysics. After recalling some of the classic work on vacuum polarization in uniform electric fields by Klein, Sauter, Heisenberg, Euler and Schwinger, we summarize some of the efforts to observe these effects in heavy ions and high energy ion collisions. We then turn to the theory of vacuum polarization around a Kerr-Newman black hole, leading to the extraction of the blackholic energy, to the concept of dyadosphere and dyadotorus, and to the creation of an electron-positron-photon plasma. We then present a new theoretical approach encompassing the physics of neutron stars and heavy nuclei. It is shown that configurations of nuclear matter in bulk with global charge neutrality can exist on macroscopic scales and with electric fields close to the critical value near their surfaces. These configurations may represent an initial condition for the...

  20. Complex transitions between spike, burst or chaos synchronization states in coupled neurons with coexisting bursting patterns

    International Nuclear Information System (INIS)

    Gu Hua-Guang; Chen Sheng-Gen; Li Yu-Ye


    We investigated the synchronization dynamics of a coupled neuronal system composed of two identical Chay model neurons. The Chay model showed coexisting period-1 and period-2 bursting patterns as a parameter and initial values are varied. We simulated multiple periodic and chaotic bursting patterns with non-(NS), burst phase (BS), spike phase (SS), complete (CS), and lag synchronization states. When the coexisting behavior is near period-2 bursting, the transitions of synchronization states of the coupled system follows very complex transitions that begins with transitions between BS and SS, moves to transitions between CS and SS, and to CS. Most initial values lead to the CS state of period-2 bursting while only a few lead to the CS state of period-1 bursting. When the coexisting behavior is near period-1 bursting, the transitions begin with NS, move to transitions between SS and BS, to transitions between SS and CS, and then to CS. Most initial values lead to the CS state of period-1 bursting but a few lead to the CS state of period-2 bursting. The BS was identified as chaos synchronization. The patterns for NS and transitions between BS and SS are insensitive to initial values. The patterns for transitions between CS and SS and the CS state are sensitive to them. The number of spikes per burst of non-CS bursting increases with increasing coupling strength. These results not only reveal the initial value- and parameter-dependent synchronization transitions of coupled systems with coexisting behaviors, but also facilitate interpretation of various bursting patterns and synchronization transitions generated in the nervous system with weak coupling strength. (paper)

  1. Long Burst Error Correcting Codes, Phase I (United States)

    National Aeronautics and Space Administration — Long burst error mitigation is an enabling technology for the use of Ka band for high rate commercial and government users. Multiple NASA, government, and commercial...

  2. Relativistic effects in gamma-ray bursts

    International Nuclear Information System (INIS)

    Eriksen, Erik; Groen, Oeyvind


    According to recent models of the sources of gamma-ray bursts the extremely energetic emission is caused by shells expanding with ultrarelativistic velocity. With the recent identification of optical sources at the positions of some gamma-ray bursts these ''fireball'' models have acquired an actuality that invites to use them as a motivating application when teaching special relativity. We demonstrate several relativistic effects associated with these models which are very pronounced due to the great velocity of the shell. For example a burst lasting for a month in the rest frame of an element of the shell lasts for a few seconds only, in the rest frame of our detector. It is shown how the observed properties of a burst are modified by aberration and the Doppler effect. The apparent luminosity as a function of time is calculated. Modifications due to the motion of the star away from the observer are calculated. (Author)

  3. Solar energetic particles and radio burst emission

    Directory of Open Access Journals (Sweden)

    Miteva Rositsa


    Full Text Available We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996–2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

  4. Solar energetic particles and radio burst emission (United States)

    Miteva, Rositsa; Samwel, Susan W.; Krupar, Vratislav


    We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996-2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection) we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

  5. Astrophysics: Burst of support for relativity (United States)

    Amelino-Camelia, Giovanni


    Light from a distant γ-ray burst backs up a key prediction of Albert Einstein's theory of relativity - that photon speed is the same regardless of energy. But it might set the stage for evolution of the theory.

  6. Observations of gamma-ray bursts

    International Nuclear Information System (INIS)

    Strong, I.B.; Klebesadel, R.W.; Evans, W.D.


    Observational data on gamma-ray bursts are reviewed. Information is grouped into temporal properties, energy fluxes and spectral properties, and directions and distributions of the sources in space. (BJG)

  7. Supernovae and gamma-ray bursts connection

    Energy Technology Data Exchange (ETDEWEB)

    Valle, Massimo Della [INAF-Napoli, Capodimonte Observatory, Salita Moiariello, 16, I-80131 Napoli (Italy); International Center for Relativistic Astrophysics Network, Piazzale della Repubblica 10, I-65122, Pescara (Italy)


    I’ll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ∼ 0.4% − 3%.

  8. A Review on Pacemakers: Device Types, Operating Modes and Pacing Pulses. Problems Related to the Pacing Pulses Detection

    Directory of Open Access Journals (Sweden)

    Valentin Tsibulko


    Full Text Available A pacemaker is a small battery-operated medical device that delivers electrical impulses to the heart in order to guarantee regular contractions. Depending on the number of active leads the pacemakers are single chamber, dual chamber and bi-ventricular. According to their programming the devices could be with fixed-rate, 'on demand' and rate-responsitive. The operating mode of the pacemaker depends on the paced chamber, the sensed chamber, the response to a sensed electrical signal and the rate modulation. Two types of pacing are recognized - unipolar and bipolar, represented with different pacing artifacts in the ECG signal. The pacing pulse on the skin surface usually have very fast rising edges of the order of 10 µs or less and could be as small as few hundreds µV. The pacing artifacts detection is important since they indicate the presence of a pacemaker and help to evaluate the reaction of the heart. All pertinent medical standards require the pacing artifacts to be captured and indicated on the screen of the device. This paper presents a short review on pacemakers - reasons for implementation, device types, different operation modes and pacing pulses. It reveals some common problems with the detection of pacemaker's artifacts.

  9. Fast Paced, Low Cost Projects at MSFC (United States)

    Watson-Morgan, Lisa; Clinton, Raymond


    What does an orbiting microsatellite, a robotic lander and a ruggedized camera and telescope have in common? They are all fast paced, low cost projects managed by Marshall Space Flight Center (MSFC) teamed with successful industry partners. MSFC has long been synonymous with human space flight large propulsion programs, engineering acumen and risk intolerance. However, there is a growing portfolio/product line within MSFC that focuses on these smaller, fast paced projects. While launching anything into space is expensive, using a managed risk posture, holding to schedule and keeping costs low by stopping at egood enough f were key elements to their success. Risk is defined as the possibility of loss or failure per Merriam Webster. The National Aeronautics and Space Administration (NASA) defines risk using procedural requirement 8705.4 and establishes eclasses f to discern the acceptable risk per a project. It states a Class D risk has a medium to significant risk of not achieving mission success. MSFC, along with industry partners, has created a niche in Class D efforts. How did the big, cautious MSFC succeed on these projects that embodied the antithesis of its heritage in human space flight? A key factor toward these successful projects was innovative industry partners such as Dynetics Corporation, University of Alabama in Huntsville (UAHuntsville), Johns Hopkins Applied Physics Laboratory (JHU APL), Teledyne Brown Engineering (TBE), Von Braun Center for Science and Innovation (VCSI), SAIC, and Jacobs. Fast Affordable Satellite Technology (FastSat HSV01) is a low earth orbit microsatellite that houses six instruments with the primary scientific objective of earth observation and technology demonstration. The team was comprised of Dynetics, UAHuntsvile, SAIC, Goddard Space Flight Center (GSFC) and VCSI with the United States Air Force Space Test Program as the customer. The team completed design, development, manufacturing, environmental test and integration in

  10. “Add-on pacing lead”: An effective and safe alternative to lead replacement in ICD pacing failure

    Directory of Open Access Journals (Sweden)

    Sudeep Kumar


    Full Text Available Despite recent advances in implantable cardioverter defibrillator (ICD technology, the long-term reliability of ICD leads remains a significant problem. Lead failures constitute a major risk for patients with an implantable cardioverter defibrillator. There is no clear consensus on treatment strategy of ICD lead failure and decision should be individualized. We report a pacing-dependent elderly male with ICD lead pacing failure secondary to insulation break resulting in recurrent syncope. We emphasize the technique of “Add-on pacing lead implantation” could be an effective and alternative to ICD lead replacement.

  11. Factors explaining voluntary participation in PACE-Vaquita


    Sara Avila


    Vaquita marina, a small species of porpoise endemic to the Northern Gulf of California in Mexico, is the world’s most endangered cetacean species. With the purpose of preserving vaquita, the Mexican government launched PACE-Vaquita in 2008. This voluntary program offers an innovative schedule of compensations: as in a payment for conservation program, PACE-Vaquita compensates for temporary reductions in fishing reductions in fishing effort; as in a program to accelerate technology adoption,PA...

  12. PACE and the Federal Housing Finance Agency (FHFA)

    Energy Technology Data Exchange (ETDEWEB)

    Zimring, Mark; Fuller, Merrian


    The FHFA regulates Fannie Mae, Freddie Mac, and the 12 Federal Home Loan Banks (the government-sponsored enterprises - GSEs). On June 18, 2009, James B. Lockhart III, then Director of FHFA, released a letter expressing concern about the negative impact of energy loan tax assessment programs (ELTAPs) - also known as Property Assessed Clean Energy (PACE) programs - on both the housing finance system and homeowner program participants. Subsequently, a number of PACE proponents responded to the concerns laid out in the FHFA letter. In early Fall 2009, word circulated that FHFA was planning to follow its June letter with guidance to other agencies, possibly including Fannie Mae and Freddie Mac, discouraging them from buying loans on properties subject to PACE-type assessment liens. This triggered a second round of stakeholder letters, several of which were addressed to President Obama. On October 18, 2009, the White House, in what some believe was an attempt to obviate the need for FHFA guidance, released a Policy Framework for PACE Financing Programs that outlined best practices guidance for homeowner and lender protection. As of February 2010, FHFA and the GSEs have agreed to monitor PACE programs and work with stakeholders and the Administration to consider additional guidance beyond the Policy Framework and to collect more information on PACE program efficacy and risks. A summary of the communications timeline and highlights of the communications are provided.

  13. ASKAP Joins the Hunt for Mysterious Bursts (United States)

    Kohler, Susanna


    A new telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), has joined the search for energetic and elusive fast radio bursts. And in just a few days of looking, its already had success!Elusive TransientsThe Parkes radio telescope, which has detected all but five of the fast radio bursts published to date, has a very narrow field of view. [CSIRO]Fast radio bursts are mysterious millisecond-duration radio pulses that were first discovered around a decade ago. Since that time particularly in recent years weve made some progress toward the goal of localizing them. Were now fairly convinced that fast radio bursts come from outside of the galaxy, and yet theyre enormously bright orders of magnitude more luminous than any pulse seen from the Milky Way.Better identification of where these mysterious bursts come from would help us to determine what they are. But so far, weve discovered only around 30 such bursts, despite the fact that theyre estimated to occur at a rate of 3,000 events per day across the whole sky.Why are they so hard to find? Due to their short duration, effective detection would require instantaneous coverage of a very large fraction of the sky. The Parkes radio telescope which has detected all but five of the fast radio bursts published to date has a field of view spanning less than a square degree,significantly limiting our ability to rapidly survey for these transients.FRB 170107s band-averaged pulse (top) and dynamic spectrum (bottom). [Bannister et al. 2017]A New Array in TownA new player is now on the scene, however, and its already had huge success. ASKAP is a wide-field radio telescope made up of an array of 12-meter antennas. Using phased-array-feed technology, ASKAP is able to instantaneously observe an effective area of 160 square degrees an enormous field compared to Parkes 0.6 square degrees! This capability significantly increases our chances of being able to detect fast radio bursts.In a new study led by Keith Bannister

  14. Method and apparatus for coherent burst ranging (United States)

    Wachter, Eric A.; Fisher, Walter G.


    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time.

  15. A Nontriggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs (United States)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.


    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the on-board burst trigger. For example, the burst may be too faint to exceed the on-board detection threshold, or it may occur while the on-board burst trigger is disabled for technical reasons. This paper describes a catalog of 873 "nontriggered" GRBs that were detected in a search of the archival continuous data from BATSE recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  16. Reduced Lordosis and Enhanced Aggression in Paced and Non-Paced Mating in Diabetic Female Rats. (United States)

    Hernández-Munive, Abigail K; Rebolledo-Solleiro, Daniela; Ventura-Aquino, Elisa; Fernández-Guasti, Alonso


    Clinical studies have shown altered sexual function in people with diabetes; basic science studies, using the streptozotocin (STZ)-induced animal model of type 1 diabetes mellitus (DM1), have consistently reported decreased sexual behavior in hyperglycemic female animals, but features of sexual motivation and aggressive behavior have not been explored in these animals. To study several parameters that denote sexual motivation in STZ-treated female rats and to compare behavioral features of sexual behavior and aggression in non-paced mating (NPM) and paced mating (PM) conditions. DM1 was induced by injecting STZ (diluted in citrate buffer) at a dose of 50 mg/kg intraperitoneally over 2 consecutive days into ovariectomized Wistar rats. 10 days later, female rats were treated with estradiol benzoate (10 μg, -24 hours) and progesterone (3 mg, -4 hours); their sexual behavior (including lordosis quotient, lordosis intensity, and proceptivity) and aggression were evaluated under NPM and PM conditions. Body weight, blood glucose levels, and spontaneous ambulatory activity also were measured. A group of STZ-treated animals was administered a long-acting insulin analogue (glargine) every 12 hours for 8 days, and their sexual and aggressive behaviors were evaluated in NPM. We quantified body weight, blood glucose level, spontaneous ambulatory activity, and sexual and aggressive behaviors in NPM and PM; the time the female rats spent interacting with the male rat or in the male rat's chamber also was registered in PM. Compared with controls, STZ-treated ovariectomized rats lost body weight, had increased blood glucose levels, and had unchanged spontaneous ambulatory activity. In the PM and NPM conditions, animals showed decreased lordosis quotient and lordosis intensity, increased aggression, and unaltered proceptivity, although in NPM the effects of STZ treatment on aggression were more drastic and were completely prevented by insulin. In PM no differences were found

  17. Sources of type III solar microwave bursts

    Directory of Open Access Journals (Sweden)

    Zhdanov D.A.


    Full Text Available Microwave fine structures allow us to study plasma evolution in an energy release region. The Siberian Solar Radio Telescope (SSRT is a unique instrument designed to examine fine structures at 5.7 GHz. A complex analysis of data from RATAN-600, 4–8 GHz spectropolarimeter, and SSRT, simultaneously with EUV data, made it possible to localize sources of III type microwave bursts in August 10, 2011 event within the entire frequency band of burst occurrence, as well as to determine the most probable region of primary energy release. To localize sources of III type bursts from RATAN-600 data, an original method for data processing has been worked out. At 5.7 GHz, the source of bursts was determined along two coordinates, whereas at 4.5, 4.7, 4.9, 5.1, 5.3, 5.5, and 6.0 GHz, their locations were identified along one coordinate. The size of the burst source at 5.1 GHz was found to be maximum as compared to those at other frequencies.

  18. Scientific Applications Performance Evaluation on Burst Buffer

    KAUST Repository

    Markomanolis, George S.


    Parallel I/O is an integral component of modern high performance computing, especially in storing and processing very large datasets, such as the case of seismic imaging, CFD, combustion and weather modeling. The storage hierarchy includes nowadays additional layers, the latest being the usage of SSD-based storage as a Burst Buffer for I/O acceleration. We present an in-depth analysis on how to use Burst Buffer for specific cases and how the internal MPI I/O aggregators operate according to the options that the user provides during his job submission. We analyze the performance of a range of I/O intensive scientific applications, at various scales on a large installation of Lustre parallel file system compared to an SSD-based Burst Buffer. Our results show a performance improvement over Lustre when using Burst Buffer. Moreover, we show results from a data hierarchy library which indicate that the standard I/O approaches are not enough to get the expected performance from this technology. The performance gain on the total execution time of the studied applications is between 1.16 and 3 times compared to Lustre. One of the test cases achieved an impressive I/O throughput of 900 GB/s on Burst Buffer.

  19. Cricket pace bowling: The trade-off between optimising knee angle ...

    African Journals Online (AJOL)

    benefits. At times this is done to the detriment of injury prevention. Objective. To investigate the relationship between three-dimensional (3D) knee kinematics during pace bowling action, injury incidence and bowling performance at .... medium pace (120 - 129 km/h); medium fast pace (130 - 139 km/h) and fast pace (≥140 ...

  20. Gamma-Ray Burst Intensity Distributions (United States)

    Band, David L.; Norris, Jay P.; Bonnell, Jerry T.


    We use the lag-luminosity relation to calculate self-consistently the redshifts, apparent peak bolometric luminosities L(sub B1), and isotropic energies E(sub iso) for a large sample of BATSE bursts. We consider two different forms of the lag-luminosity relation; for both forms the median redshift, for our burst database is 1.6. We model the resulting sample of burst energies with power law and Gaussian dis- tributions, both of which are reasonable models. The power law model has an index of a = 1.76 plus or minus 0.05 (95% confidence) as opposed to the index of a = 2 predicted by the simple universal jet profile model; however, reasonable refinements to this model permit much greater flexibility in reconciling predicted and observed energy distributions.

  1. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra


    Full Text Available Gamma-ray bursts (GRBs are extremely energetic events at cosmological distances. They provide unique laboratory to investigate fundamental physical processes under extreme conditions. Due to extreme luminosities, GRBs are detectable at very high redshifts and potential tracers of cosmic star formation rate at early epoch. While the launch of Swift and Fermi has increased our understanding of GRBs tremendously, many new questions have opened up. Radio observations of GRBs uniquely probe the energetics and environments of the explosion. However, currently only 30% of the bursts are detected in radio bands. Radio observations with upcoming sensitive telescopes will potentially increase the sample size significantly and allow one to follow the individual bursts for a much longer duration and be able to answer some of the important issues related to true calorimetry, reverse shock emission, and environments around the massive stars exploding as GRBs in the early Universe.

  2. Localised Microwave Bursts During ELMs on MAST

    Directory of Open Access Journals (Sweden)

    Freethy Simon


    Full Text Available Bursts of microwave emission are observed during ELM events on the Mega Ampère Spherical Tokamak. In agreement with observations on other machines, these bursts are up to 3 orders of magnitude more intense than the thermal background, but are electron cyclotron in nature. The peak in microwave emission is ~20μ before the peak in midplane Dα emission. Using the Synthetic Aperture Microwave Imaging radiometer, we are able to demonstrate that these bursts are often highly spatially localised and preferentially occur at the tokamak midplane. It is hypothesised that the localisation is a result of Doppler resonance broadening for electron Bernstein waves and the high perpendicular electron energies could be the result of pitch angle scattering in high collisionality regions of the plasma.

  3. Gamma Ray Bursts Observations and Theoretical Conjectures

    CERN Document Server

    Alagoz, E; Carrillo, C; Golup, G T; Grimes, M; Herrera, Mora C; Gallo, Palomino J L; López, Vega A; Wicht, J


    Gamma Ray Bursts (GRBs) are short bursts of very high energy photons which were discovered in the late 1960s. Ever since their discovery, scientists have wondered about their origin. Nowadays it is known that they originate outside the Milky Way because of their high red shift rst measured in the afterglows thanks to the Beppo-SAX satellite and ground-based observations. However, theoreticians still do not agree about the mechanism that generates the bursts, and different competing models are animatedly debated. Current GRB experiments include the Swift satellite and the Pierre Auger Observatory that could detect GRBs with an increase of the background. A forthcoming dedicated experiment is GLAST, a satellite observatory for detecting gamma rays with energies up to 300 GeV, whose launch is scheduled for early 2008.

  4. X-ray bursts observed with JEM-X

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Chenevez, Jérôme; Lund, Niels


    We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found.......We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found....

  5. Broadband Spectral Investigations of Magnetar Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin, E-mail: [Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı Tuzla, Istanbul 34956 (Turkey)


    We present our broadband (2–250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550−5418, SGR 1900+14, and SGR 1806−20 detected with the Rossi X-ray Timing Explorer ( RXTE ) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  6. Broadband Spectral Investigations of Magnetar Bursts (United States)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin


    We present our broadband (2-250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550-5418, SGR 1900+14, and SGR 1806-20 detected with the Rossi X-ray Timing Explorer (RXTE) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  7. BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long bursts (United States)

    Ford, L. A.; Band, D. L.; Matteson, J. L.; Briggs, M. S.; Pendleton, G. N.; Preece, R. D.; Paciesas, W. S.; Teegarden, B. J.; Palmer, D. M.; Schaefer, B. E.


    We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) spectroscopy detectors. High-resolution spectra are chracterized by the energy of the peak of nu F(sub nu), and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak energy either rises with or slightly precedes major intensity increases and softens for the remainder of the pulse. Interpulse emission is generally harder early in the burst. For bursts with multiple intensity pulses, later spikes tend to be softer than earlier ones, indicating that the energy of the peak of nu F(sub nu) is bounded by an envelope which decays with time. Evidence is found that bursts in which the bulk of the flux comes well after the event which triggers the instrument tend to show less peak energy variability and are not as hard as several bursts in which the emission occurs promptly after the trigger. Several recently proposed burst models are examined in light of these results and no qualitative conflicts with the observations presented here are found.


    Energy Technology Data Exchange (ETDEWEB)

    Ukwatta, T. N. [Director' s Postdoctoral Fellow, Space and Remote Sensing (ISR-2), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hurley, K. [University of California, Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); MacGibbon, J. H. [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal' shin, V. D. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Goldsten, J. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Boynton, W. [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); Kozyrev, A. S. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Rau, A.; Kienlin, A. von; Zhang, X. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, Garching, D-85748 (Germany); Connaughton, V. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Yamaoka, K. [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 (Japan); Ohno, M. [Department of Physics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ohmori, N. [Department of Applied Physics, University of Miyazaki, 1-1 Gakuen kibanadai-nishi, Miyazaki-shi, Miyazaki 889-2192 (Japan); Feroci, M. [INAF/IAPS-Roma, via Fosso del Cavaliere 100, I-00133, Roma (Italy); Frontera, F., E-mail: [Department of Physics and Earth Science, University of Ferrara, via Saragat 1, I-44122 Ferrara (Italy); and others


    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 10{sup 13}–10{sup 18} cm (7–10{sup 5} au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

  9. Radon and rock bursts in deep mines

    International Nuclear Information System (INIS)

    Bulashevich, Yu.P.; Utkin, V.I.; Yurkov, A.K.; Nikolaev, V.V.


    Variation fields of radon concentration in time to ascertain stress-strain state of the North Ural bauxite mines have been studied. It is shown that dynamic changes in the stress-strain state of the rocks prior to the rock burst bring about variations in radon concentration in the observation wells. Depending on mutual positioning of the observation points and the rock burst epicenter, the above-mentioned variations differ in principle, reduction of radon concentration in the near zone and its increase in the far zone are observed [ru

  10. Spike Bursts from an Excitable Optical System (United States)

    Rios Leite, Jose R.; Rosero, Edison J.; Barbosa, Wendson A. S.; Tredicce, Jorge R.

    Diode Lasers with double optical feedback are shown to present power drop spikes with statistical distribution controllable by the ratio of the two feedback times. The average time between spikes and the variance within long time series are studied. The system is shown to be excitable and present bursting of spikes created with specific feedback time ratios and strength. A rate equation model, extending the Lang-Kobayashi single feedback for semiconductor lasers proves to match the experimental observations. Potential applications to construct network to mimic neural systems having controlled bursting properties in each unit will be discussed. Brazilian Agency CNPQ.

  11. Spectral Tests of the Homogeneity of Gamma-Ray Bursts (United States)

    Band, David L.


    We proposed to determine whether the spectral-hardness-intensity relation found when comparing dim and bright bursts is also found within the set of bright bursts. In the simplest cosmological burst paradigm all bursts have the same intrinsic brightness (they are "standard candles") and the faintest BATSE bursts are at a redshift of approx. 1. The cumulative intensity distribution, which is a -3/2 power law at the bright end but flatter at the low intensity end, is explained by the cosmological curvature of space. Thus bursts at the bright end should be at such low redshifts that they do not suffer cosmological redshifting of their spectra or time dilation of their lightcurves. The spectral-hardness and burst intensity are correlated when dim and bright bursts are compared, consistent with cosmological redshifting. However, the actual redshifts of a number of bursts have been determined, showing that bursts are not standard candles, and that their redshifts are frequently greater than approx. 1; the maximum redshift is 3.4! Consequently many bright bursts are at redshifts where cosmological effects are significant. We had proposed to determine A,hether the redshifting effect continued into the bright bursts; even moderately bright bursts should be at cosmological distances.

  12. Powerful Radio Burst Indicates New Astronomical Phenomenon (United States)


    Astronomers studying archival data from an Australian radio telescope have discovered a powerful, short-lived burst of radio waves that they say indicates an entirely new type of astronomical phenomenon. Region of Strong Radio Burst Visible-light (negative greyscale) and radio (contours) image of Small Magellanic Cloud and area where burst originated. CREDIT: Lorimer et al., NRAO/AUI/NSF Click on image for high-resolution file ( 114 KB) "This burst appears to have originated from the distant Universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said Duncan Lorimer, Assistant Professor of Physics at West Virginia University (WVU) and the National Radio Astronomy Observatory (NRAO). The research team led by Lorimer consists of Matthew Bailes of Swinburne University in Australia, Maura McLaughlin of WVU and NRAO, David Narkevic of WVU, and Fronefield Crawford of Franklin and Marshall College in Lancaster, Pennsylvania. The astronomers announced their findings in the September 27 issue of the online journal Science Express. The startling discovery came as WVU undergraduate student David Narkevic re-analyzed data from observations of the Small Magellanic Cloud made by the 210-foot Parkes radio telescope in Australia. The data came from a survey of the Magellanic Clouds that included 480 hours of observations. "This survey had sought to discover new pulsars, and the data already had been searched for the type of pulsating signals they produce," Lorimer said. "We re-examined the data, looking for bursts that, unlike the usual ones from pulsars, are not periodic," he added. The survey had covered the Magellanic Clouds, a pair of small galaxies in orbit around our own Milky Way Galaxy. Some 200,000 light-years from Earth, the Magellanic Clouds are prominent features in the Southern sky. Ironically, the new discovery is not part of these galaxies, but rather is much more distant

  13. Cardiac Pacing and Defibrillation in Children and Young Adults

    Directory of Open Access Journals (Sweden)

    Harinder R. Singh, MD, CCDS


    Full Text Available The population of children and young adults requiring a cardiac pacing device has been consistently increasing. The current generation of devices are small with a longer battery life, programming capabilities that can cater to the demands of the young patients and ability to treat brady and tachyarrhythmias as well as heart failure. This has increased the scope and clinical indications of using these devices. As patients with congenital heart disease (CHD comprise majority of these patients requiring devices, the knowledge of indications, pacing leads and devices, anatomical variations and the technical skills required are different than that required in the adult population. In this review we attempt to discuss these specific points in detail to improve the understanding of cardiac pacing in children and young adults.

  14. The solarPACES strategy for the solar thermal breakthrough

    International Nuclear Information System (INIS)

    Burch, G.D.; Grasse, W.


    IEA(International Energy Agency)/SolarPACES(Solar Power and Chemical Energy systems)represents a world wide coalition for information sharing and collaboration on applications of concentrated solar energy. The current SolarPACES community has built up solar thermal system know-how over 15 years, is operating the three main solar test centres in the world. Its main activities are in the following four fields: solar thermal electric power systems, solar chemistry, solar technology and advanced applications and non-technical activities. The article presents the talk on the strategy of solarPACES given at the International Workshop on applied solar energy held in Tashkent(Uzbekistan) in June 1997. (A.A.D.)

  15. Pacing during an ultramarathon running event in hilly terrain

    Directory of Open Access Journals (Sweden)

    Hugo A. Kerhervé


    Full Text Available Purpose The dynamics of speed selection as a function of distance, or pacing, are used in recreational, competitive, and scientific research situations as an indirect measure of the psycho-physiological status of an individual. The purpose of this study was to determine pacing on level, uphill and downhill sections of participants in a long (>80 km ultramarathon performed on trails in hilly terrain. Methods Fifteen ultramarathon runners competed in a  173 km event (five finished at  103 km carrying a Global-Positioning System (GPS device. Using the GPS data, we determined the speed, relative to average total speed, in level (LEV, uphill (UH and downhill (DH gradient categories as a function of total distance, as well as the correlation between overall performance and speed variability, speed loss, and total time stopped. Results There were no significant differences in normality, variances or means in the relative speed in 173-km and 103-km participants. Relative speed decreased in LEV, UH and DH. The main component of speed loss occurred between 5% and 50% of the event distance in LEV, and between 5% and 95% in UH and DH. There were no significant correlations between overall performance and speed loss, the variability of speed, or total time stopped. Conclusions Positive pacing was observed at all gradients, with the main component of speed loss occurring earlier (mixed pacing in LEV compared to UH and DH. A speed reserve (increased speed in the last section was observed in LEV and UH. The decrease in speed and variability of speed were more important in LEV and DH than in UH. The absence of a significant correlation between overall performance and descriptors of pacing is novel and indicates that pacing in ultramarathons in trails and hilly terrain differs to other types of running events.

  16. Pace: an advanced structure for handling multi-technique NDT

    International Nuclear Information System (INIS)

    Mayos, M.; Guisnel, F.


    The growing extent and complexity of NDT data analysis has reached a stage where dedicated systems are required. In the context of a European research program, EDF participated from 1992 to 1994 in one of the first international projects in this field, TRAPPIST and, in 1993, began developing An application for the electricity generating industry, giving rise to the PACE project. The prime objective specially targets the French electricity generating industry, where PACE was to be the reference system for analysis of NDE data concerning EdF power plants. The second objective is to promote the adoption of PACE by other industrial sectors and other countries. The analysis of needs shows that the required system must be designed to analyze data from widely different sources. The PACE entry point consequently has to be a standard format compatible with geometrical data as well as those provided by NDT. The TRAPPIST format constitutes the first version of this standard and is the first step towards European standardization in this respect. Consideration of the different user modes defined for PACE led to the design of a 2-part user structure comprising a database management system (Ingres/Windows 4GL) and a display/processing tool (AVS), also usable to construct analysis scenarios. The structure of PACE is defined nd seems well suited to industrial requirements, but before it is possible to proceed further towards its adoption for actual power plant inspections, it has to be validated on a more realistic application, the eddy current and ultrasonic testing of a full-scale T-joint. This is already under way, whilst work on format standardization and industrialization preparatory procedures are proceeding in parallel. (authors). 4 refs., 6 figs

  17. Pattern and pace of dental eruption in Tarsius. (United States)

    Guthrie, Emily H; Frost, Stephen R


    This article uses data on the dental eruption pattern and life history of Tarsius to test the utility of Schultz's rule. Schultz's rule claims a relationship between the relative pattern of eruption and the absolute pace of dental development and life history and may be useful in reconstructing life histories in extinct primates. Here, we document an unusual eruption pattern in Tarsius combining early eruption (relative to molars) of anterior replacement teeth (P2 and incisors) and relatively late eruption of the posterior replacement teeth (C, P3, and P4). This eruption pattern does not accurately predict the "slow" pace of life documented for Tarsius [Roberts: Int J Primatol 15 (1994) 1-28], nor aspects of life history directly associated with dental development as would be expected using Schultz's rule. In Tarsius, the anterior teeth and M1 erupt at an early age and therefore are not only fast in a relative sense but also fast in an absolute sense. This seems to be related to a developmental anomaly in the deciduous precursor teeth, which are essentially skipped. This decoupling among dental eruption pattern, dental eruption pace, and life history pace in Tarsius undermines the assumptions that life histories can accurately be described as "fast" or "slow" and that dental eruption pattern alone can be used to infer overall life history pace. The relatively and absolutely early eruption of the anterior dentition may be due to the utility of these front teeth in early food acquisition rather than with the pace of life history. Copyright © 2011 Wiley-Liss, Inc.

  18. BACODINE/3rd Interplanetary Network burst localization

    International Nuclear Information System (INIS)

    Hurley, K.; Barthelmy, S.; Butterworth, P.; Cline, T.; Sommer, M.; Boer, M.; Niel, M.; Kouveliotou, C.; Fishman, G.; Meegan, C.


    Even with only two widely separated spacecraft (Ulysses and GRO), 3rd Interplanetary Network (IPN) localizations can reduce the areas of BATSE error circles by two orders of magnitude. Therefore it is useful to disseminate them as quickly as possible following BATSE bursts. We have implemented a system which transmits the light curves of BACODINE/BATSE bursts directly by e-mail to UC Berkeley immediately after detection. An automatic e-mail parser at Berkeley watches for these notices, determines the Ulysses crossing time window, and initiates a search for the burst data on the JPL computer as they are received. In ideal cases, it is possible to retrieve the Ulysses data within a few hours of a burst, generate an annulus of arrival directions, and e-mail it out to the astronomical community by local nightfall. Human operators remain in this loop, but we are developing a fully automated routine which should remove them, at least for intense events, and reduce turn-around times to an absolute minimum. We explain the current operations, the data types used, and the speed/accuracy tradeoffs

  19. Radio Afterglows of Gamma Ray Bursts

    Indian Academy of Sciences (India)

    Gamma ray bursts; radio astronomy. ... Even though radio band is the least explored of the afterglow spectrum, it has played an important role in the progress of GRB physics, specifically in confirming the hypothesized relativistic effects. ... Indian Institute of Space Science and Technology, Trivandrum 695 547, India.

  20. Search for bursts in air shower data

    International Nuclear Information System (INIS)

    Bruce, T.E.G.; Clay, R.W.; Dawson, B.R.; Protheroe, R.J.; Blair, D.G.; Cinquini, P.


    There have been reports in recent years of the possible observation of bursts in air shower data. If such events are truly of an astrophysical nature then, they represent an important new class of phemonenon since no other bursts have been observed above the MeV level. The spectra of conventional gamma ray bursts are unknown at higher energies but their observed spectra at MeV energies appear generally to exhibit a steepening in the higher MeV range and are thus unlikely to extrapolate to measurable fluxes at air shower energies. An attempt has been made to look for deviations from randomness in the arrival times of air showers above approx. 10 to the 14th power eV with a number of systems and results so far are presented here. This work will be continued for a substantial period of time with a system capable of recording bursts with multiple events down to a spacing of 4 microns. Earlier data have also been searched for the possible association of air shower events with a glitch of the Vela pulsar

  1. Gamma-Ray Bursts and Cosmology (United States)

    Norris, Jay P.


    The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities must be calibrated, and the luminosity function versus redshift must be measured or inferred. Several nascent relationships between gamma-ray temporal or spectral indicators and luminosity or total energy have been reported. These measures promise to further our understanding of GRBs once the connections between the luminosity indicators and GRB jets and emission mechanisms are better elucidated. The current distribution of 33 redshifts determined from host galaxies and afterglows peaks near z $\\sim$ 1, whereas for the full BATSE sample of long bursts, the lag-luminosity relation predicts a broad peak z $\\sim$ 1--4 with a tail to z $\\sim$ 20, in rough agreement with theoretical models based on star formation considerations. For some GRB subclasses and apparently related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the present information on their redshift distributions is sparse or entirely lacking, and progress is expected in Swift era when prompt alerts become numerous.

  2. Magnetized environs of a repeating radio burst (United States)

    Metzger, Brian D.


    One of the astrophysical sources that gives rise to the mysterious transients known as fast radio bursts is embedded in a highly magnetized environment, such as the vicinity of an accreting massive black hole or the birth nebula of a highly magnetized neutron star.

  3. Spectral Lag Evolution among -Ray Burst Pulses

    Indian Academy of Sciences (India)


    Jan 27, 2016 ... We analyse the spectral lag evolution of -ray burst (GRB) pulses with observations by CGRO/BATSE. No universal spectral lag evolution feature and pulse luminosity-lag relation within a GRB is observed.Our results suggest that the spectral lag would be due to radiation physics and dynamics of a given ...

  4. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    Wijers, R.A.M.J.


    Gamma-ray bursts are much brighter than supernovae, and could therefore possibly probe the Universe to high redshift. The presently established GRB redshifts range from 0.83 to 5, and quite possibly even beyond that. Since most proposed mechanisms for GRB link them closely to deaths of massive

  5. Positron annihilation in gamma-ray bursts (United States)

    Harding, Alice K.


    Emission features appear at energies of 350 to 450 keV in the spectra of a number of gamma ray burst sources. These features were interpreted as electron-positron annihilation lines, redshifted by the gravitational field near the surface of a neutron star. Evidence that gamma ray bursts originate at neutron stars with magnetic field strengths of approx. 10(exp 12) Gauss came from recent observations of cyclotron scattering harmonics in the spectra of two bursts. Positrons could be produced in gamma ray burst sources either by photon-photon pair production or by one-photon pair production in a strong magnetic field. The annihilation of positrons is affected by the presence of a strong neutron star magnetic field in several ways. The relaxation of transverse momentum conservation causes an intrinsic broadening of the two-photon annihilation line and there is a decrease in the annihilation cross section below the free-space value. An additional channel for one-photon annihilation also becomes possible in high magnetic fields. The physics of pair production and annihilation near strongly magnetized neutron stars will be reviewed. Results from a self-consistent model for non-thermal synchrotron radiation and pair annihilation are beginning to identify the conditions required to produce observable annihilation features from strongly magnetized plasmas.

  6. BurstMem: A High-Performance Burst Buffer System for Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Teng [Auburn University, Auburn, Alabama; Oral, H Sarp [ORNL; Wang, Yandong [Auburn University, Auburn, Alabama; Settlemyer, Bradley W [ORNL; Atchley, Scott [ORNL; Yu, Weikuan [Auburn University, Auburn, Alabama


    The growth of computing power on large-scale sys- tems requires commensurate high-bandwidth I/O system. Many parallel file systems are designed to provide fast sustainable I/O in response to applications soaring requirements. To meet this need, a novel system is imperative to temporarily buffer the bursty I/O and gradually flush datasets to long-term parallel file systems. In this paper, we introduce the design of BurstMem, a high- performance burst buffer system. BurstMem provides a storage framework with efficient storage and communication manage- ment strategies. Our experiments demonstrate that BurstMem is able to speed up the I/O performance of scientific applications by up to 8.5 on leadership computer systems.

  7. Is there cosmological time dilation in gamma-ray bursts? (United States)

    Band, David L.


    Norris et al. report that the temporal structure of faint gamma-ray bursts is longer than that of bright bursts, as expected for time dilation in the cosmological models of burst origin. I show that the observed trends can easily be produced by a burst luminosity function and thus may not result from cosmological effects. A cosmological signature may be present, but the tests Norris et al. present are not powerful enough to detect these signatures.

  8. A Turbo-Coded Burst-by-Burst Adaptive Wide-Band Speech Transceiver


    Keller, T.; Münster, M.; Hanzo, L.


    Turbo-coded burst-by-burst adaptive orthogonal frequency division multiplex (AOFDM) wide-band speech transceivers are proposed. A constant throughput adaptive OFDM transceiver was designed and benchmarked against a time-variant rate scheme. The proposed joint adaptation of source-codec, channel-codec, and modulation regime results in attractive, robust, high-quality audio systems, capable of conveying near-unimpaired wide-band audio signals over fading dispersive channels for signal-to-noise ...

  9. IGR J17254-3257, a new bursting neutron star

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Falanga, M.; Kuulkers, E.


    Aims. The study of the observational properties of uncommonly long bursts from low luminosity sources is important when investigating the transition from a hydrogen - rich bursting regime to a pure helium regime and from helium burning to carbon burning as predicted by current burst theories. On ...

  10. 46 CFR 154.554 - Cargo hose: Bursting pressure. (United States)


    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure of...

  11. Detecting Pipe Bursts Using Heuristic and CUSUM Methods

    NARCIS (Netherlands)

    Bakker, M.; Jung, D.; Vreeburg, J.; Van de Roer, M.; Lansey, K.; Rierveld, L.


    Pipe bursts in a drinking water distribution system lead to water losses, interruption of supply, and damage to streets and houses due to the uncontrolled water flow. To minimize the negative consequences of pipe bursts, an early detection is necessary. This paper describes a heuristic burst

  12. 47 CFR 90.250 - Meteor burst communications. (United States)


    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject to...

  13. Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function

    Energy Technology Data Exchange (ETDEWEB)

    Ferro, Adele; Salvatore, Marco; Cuocolo, Alberto [University Federico II, Department of Biomorphological and Functional Sciences, Institute of Biostructure and Bioimages of the National Council of Research, Naples (Italy); Duilio, Carlo; Santomauro, Maurizio [University Federico II, Department of Clinical Medicine, Cardiovascular and Immunological Sciences, Naples (Italy)


    Dual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function. Twelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction {>=}50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system. In patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test). Compared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function. (orig.)

  14. Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function

    International Nuclear Information System (INIS)

    Ferro, Adele; Salvatore, Marco; Cuocolo, Alberto; Duilio, Carlo; Santomauro, Maurizio


    Dual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function. Twelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction ≥50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system. In patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test). Compared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function. (orig.)

  15. Self-Paced Physics, Segment 41A-41E. (United States)

    New York Inst. of Tech., Old Westbury.

    The second review segment of the Self-Paced Physics Course is presented in this volume and arranged to match study segments 19 through 40. The segment is divided into five subsegments, each of which is composed of a set of problems and solutions. A study guide is provided for each subsegment. The problem set is designed in a back-referencing…

  16. Self-Paced Physics, Segments 15-17. (United States)

    New York Inst. of Tech., Old Westbury.

    Three review segments of the Self-Paced Physics Course materials are provided in this volume which is arranged to match study segments 1 through 14. Each of the three segments is composed of a set of problems and solutions, and accompanied by its own individual study guide. The problem set is designed as a back-referencing system, and the…

  17. Self-Paced Physics, Segments 6-10. (United States)

    New York Inst. of Tech., Old Westbury.

    Five segments of the Self-Paced Physics Course materials are presented in this problems and solutions book for use as the second part of student course work. The subject-matter topics are related to circular motion, work, power, kinetic energy, potential energy, conservative forces, conservation of energy, spring problems, center of mass, and…

  18. Self-Paced Physics, Segments 11-14. (United States)

    New York Inst. of Tech., Old Westbury.

    Four segments of the Self-Paced Physics Course materials are presented in this problems and solutions book for use as the third part of student course work. The subject-matter topics are related to impulses, inelastic and elastic collisions, two-dimensional collision problems, universal constant of gravitation, gravitational acceleration and…

  19. Self-Paced Physics, Segments 28-31. (United States)

    New York Inst. of Tech., Old Westbury.

    Four study segments of the Self-Paced Physics Course materials are presented in this sixth problems and solutions book used as a part of student course work. The subject matter is related to electric currents, current densities, resistances, Ohm's law, voltages, Joule heating, electromotive forces, single loop circuits, series and parallel…

  20. Individualized Self-Pacing (ISP)--A Success Story. (United States)

    Collings, Melvin R.


    Examines Fullerton College's individualized self-pacing (ISP) program. Reviews twelve ISP objectives including provision of enrollment/scheduling flexibility; lists twenty-two class offerings, including basic business math, business English, and business machines. Compares costs, learning, and course completion in ISP and traditional programs.…

  1. Design Recommendations for Self-Paced Online Faculty Development Courses (United States)

    Rizzuto, Melissa


    An increased need for self-paced, online professional development opportunities in higher education has emerged from a variety of factors including dispersed geographic locations of faculty, full teaching loads, and institutional evaluation requirements. This article is a report of the examination of the design and evaluation of a self-paced…

  2. Hardware packet pacing using a DMA in a parallel computer (United States)

    Chen, Dong; Heidelberger, Phillip; Vranas, Pavlos


    Method and system for hardware packet pacing using a direct memory access controller in a parallel computer which, in one aspect, keeps track of a total number of bytes put on the network as a result of a remote get operation, using a hardware token counter.

  3. "Set the Pace": Nutrition Education DVD for Head Start Parents (United States)

    Adedze, Pascasie; Orr, Robin A.; Chapman-Novakofski, Karen; Donovan, Sharon M.


    Childhood overweight remains a major public health problem and innovative nutrition education programs are still needed. Thus, the "Set the Pace" is a nutrition education DVD for Head Start parents which provides visual nutrition education and physical activities to incorporate in their daily routines. (Contains 1 table.)

  4. The influence of pacing strategy on marathon world records. (United States)

    Díaz, José Joaquín; Fernández-Ozcorta, Eduardo José; Santos-Concejero, Jordan


    The aim of this study was to analyse the influence of the pacing strategy adopted by elite marathon runners when setting every marathon world record in the last 50 years. We divided former marathon record holders into two groups: classic athletes (record holders between 1967 and 1988) and contemporaneous athletes (record holders between 1988 and 2018). The total distance of the marathon was divided into 8 sections of 5 km and 1 last section of 2.195 km, and the relative average speed of each section was calculated individually. On average athletes were slightly faster in the first half-marathon than in the second one, where they slowed down progressively (ES = 0.28, small effect). However, when comparing classic vs. contemporaneous athletes, we observed that classic athletes started significantly faster (p < .05, ES = 1.16, moderate effect), although after 25 km, their speed dropped dramatically and was significantly slower than in their contemporaneous counterparts (ES = 2.41, very large effect). This study shows that the pacing strategies of the best marathon runners in the world have changed over the last 50 years. Although a negative pace distribution has been proposed as the most efficient option, a pacing strategy characterised by very little speed changes across the whole race may be the way to go in the future.

  5. MFTF-B PACE tests and final cost report

    International Nuclear Information System (INIS)

    Krause, K.H.; Kozman, T.A.; Smith, J.L.; Horan, R.J.


    The Mirror Fusion Test Facility (MFTF-B) construction project was successfully completed in February 1986, with the conclusion of the Plant and Capital Equipment (PACE) Tests. This series of tests, starting in September 1985 and running through February 1986, demonstrated the overall machine capabilities and special facilities accomplishments for the Mirror Fusion Test Facility Project

  6. Pacing pattern in a 30-minute maximal cycling test. (United States)

    Chaffin, Morgan E; Berg, Kris; Zuniga, Jorge; Hanumanthu, Vidya Sagar


    The purpose of this study was to investigate the pacing pattern and associated physiological effects in competitive cyclists who performed a 30-minute maximal cycling test. Measurements included oxygen uptake (V O2), heart rate (HR), blood lactate concentration (BLC), rating of perceived exertion (RPE), and work rate in watts. Twelve well-trained amateur cyclists (seven men and five women) whose mean age was 32.4 +/- 8.6 years participated in this study. They performed a 30-minute self-paced maximal cycling test using their own performance road bike attached to a CompuTrainer Pro, which allowed the assessment of work rate (W). During the test, work rate, V O2, and HR were measured every 30 seconds. Subjects' BLC and RPE were obtained every 5 minutes. Results indicate that no significant differences existed across three 10-minute periods for work rate, HR, or V O2. However, RPE at 30 minutes was significantly greater than RPE at 10 and 20 minutes (both p minutes was also greater than the RPE at 10 minutes (p 30 seconds of the test. The associated V O2 was fairly constant over time, whereas HR rose linearly and gradually. It was concluded that pacing in a 30-minute maximal exercise bout performed in the laboratory in experienced cyclists varies minimally until the last 30 seconds. Knowledge of pacing strategy and the linked physiological responses may be helpful to exercise scientists in optimizing performance in the endurance athlete.

  7. Optimizing Classroom Instruction through Self-Paced Learning Prototype (United States)

    Bautista, Romiro G.


    This study investigated the learning impact of self-paced learning prototype in optimizing classroom instruction towards students' learning in Chemistry. Two sections of 64 Laboratory High School students in Chemistry were used as subjects of the study. The Quasi-Experimental and Correlation Research Design was used in the study: a pre-test was…

  8. Determination of myocardial energetic output for cardiac rhythm pacing

    Czech Academy of Sciences Publication Activity Database

    Heřman, D.; Převorovská, Světlana; Maršík, František


    Roč. 7, č. 4 (2007), s. 156-161 ISSN 1567-8822 R&D Projects: GA ČR GA106/03/1073 Institutional research plan: CEZ:AV0Z20760514 Keywords : heart arrhythmia * cardiac pacing modes * numerical simulation Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  9. The Pace and Shape of Senescence in Angiosperms

    DEFF Research Database (Denmark)

    Baudisch, Annette; Salguero-Gómez, Roberto; Jones, Owen


    not senesce. We find that growth form relates to differences in pace, that is, life span, as woody plants are typically longer lived than nonwoody plants, while differences in shape, that is, whether or not angiosperms senesce, are related to ancestral history. 5. Synthesis: The age trajectory of mortality...

  10. Self-Paced Physics, Segments 37-40. (United States)

    New York Inst. of Tech., Old Westbury.

    Four study segments of the Self-Paced Physics Course materials are presented in this eighth problems and solutions book used as a part of course assignments. The content is related to magnetic induction, Faraday's law, induced currents, Lenz's law, induced electromotive forces, time-varying magnetic fields, self-inductance, inductors,…

  11. Keeping Pace with K-12 Online Learning, 2016 (United States)

    Gemin, Butch; Pape, Larry


    "Keeping Pace with K-12 Online Learning 2016" marks the thirteenth consecutive year Evergreen has published its annual research of the K-12 education online learning market. The thirteen years of researching, writing and publishing this report represents a time of remarkable change. There has been a constant presence that has become the…

  12. The Effects of Self-Paced Blended Learning of Mathematics (United States)

    Balentyne, Phoebe; Varga, Mary Alice


    As online and blended learning gain more popularity in education, it becomes more important to understand their effects on student learning. The purpose of this study was to explore the effects of self-paced blended learning of mathematics on the attitudes and achievement of 26 high ability middle school students, and investigate the relationship…

  13. Gait Coordination After Stroke: Benefits of Acoustically Paced Treadmill Walking

    NARCIS (Netherlands)

    Roerdink, M.; Lamoth, C.J.C.; Kwakkel, G.; van Wieringen, P.C.W.; Beek, P.J.


    Background and Purpose: Gait coordination often is compromised after stroke. The purpose of this study was to evaluate the efficacy of acoustically paced treadmill walking as a method for improving gait coordination in people after stroke. Participants: Ten people after stroke volunteered for the

  14. Gait coordination after stroke: benefits of acoustically paced treadmill walking.

    NARCIS (Netherlands)

    Roerdink, M.; Lamoth, C.J.; Kwakkel, G.; Wieringen, P.C. van; Beek, P.J.


    BACKGROUND AND PURPOSE: Gait coordination often is compromised after stroke. The purpose of this study was to evaluate the efficacy of acoustically paced treadmill walking as a method for improving gait coordination in people after stroke. PARTICIPANTS: Ten people after stroke volunteered for the

  15. Phantom bursting is highly sensitive to noise and unlikely to account for slow bursting in beta-cells

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram


    Pancreatic beta-cells show bursting electrical activity with a wide range of burst periods ranging from a few seconds, often seen in isolated cells, over tens of seconds (medium bursting), usually observed in intact islets, to several minutes. The phantom burster model [Bertram, R., Previte, J...

  16. Diagnostics from three rising submillimeter bursts

    International Nuclear Information System (INIS)

    Zhou, Ai-Hua; Li, Jian-Ping; Wang, Xin-Dong


    In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequentially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz −1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz −1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%–50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarelativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radiation loss in the THz range, although the modeled THz source area is 3–4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 10 33 , 3.9 × 10 33 and 3.7 × 10 32 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 10 31 , 2.1 × 10 31 and 5.2 × 10 31 erg estimated from soft X-ray GOES observations. (paper)


    Energy Technology Data Exchange (ETDEWEB)

    Pal' shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Cline, T.; Trombka, J.; McClanahan, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Boynton, W.; Fellows, C.; Harshman, K., E-mail: [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); and others


    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  18. X-ray burst observations of Serpens X-1 (United States)

    Sztajno, M.; Basinska, E. M.; Cominsky, L. R.; Marshall, F. J.; Lewin, W. H. G.


    Fifty-seven X-ray bursts observed with SAS 3 in the period 1976 July to 1979 March are reported. Their general features (e.g., maximum burst flux, integrated burst flux, spectral hardness, and rise time) and the relations between them are discussed. Also a comparison is made between these burst features and the associated persistent X-ray flux. The latter appears to be correlated with the maximum burst flux; the temperature of the plasma that produces the persistent flux is roughly proportional to this flux.

  19. Pacing, Pixels, and Paper: Flexibility in Learning Words from Flashcards

    Directory of Open Access Journals (Sweden)

    Kara Sage


    Full Text Available The present study focused on how self-control over pace might help learners successfully extract information from digital learning aids. Past research has indicated that too much control over pace can be overwhelming, but too little control over pace can be ineffective. Within the popular self-testing domain of flashcards, we sought to elucidate the optimal level of user control for digital learning and compare learning outcomes between paper and digital flashcards. College students learned vocabulary from paper flashcards or one of several digital flashcard versions and were scored on their memory recall and asked about their perceptions of the learning process. With digital flashcards, students were randomly assigned to an automatic slideshow of cards with no user control, automatic slideshow with pre-set pauses, automatic slideshow where users could press the spacebar to pause at any time, or a self-paced slideshow with complete user control. Users reported feeling more in control when indeed having some control, but ultimately memory recall, cognitive load, and satisfaction were similar across the five versions. However, memory recall was positively related to user satisfaction with their specific flashcard set, and negatively related to users’ perceived mental effort and difficulty. Notably, whether paper or digital, students showed individual variability in how they advanced through the words. This research adds to the educational literature by suggesting that paper and digital flashcards are equally viable options for students. Given differences between individual users and the connection between satisfaction and recall, individualistic options that offer, but do not force, some control over pace seem ideal. Paper flashcards may already include such options, and e-flashcards should offer similar adaptive features to appeal to a wide variety of users.

  20. Advances in Atmospheric Correction for NASA's PACE mission (United States)

    Remer, L. A.; Franz, B. A.; Boss, E.


    The PACE (Pre- Aerosol, Clouds and ocean Ecosystem) mission is a strategic Climate Continuity mission, included in NASA's 2010 plan: "Responding to the Challenge of Climate and Environmental Change: NASA's Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space". On a polar orbit, PACE will make climate-quality global measurements that are essential for understanding ocean biology, biogeochemistry, ecology, aerosol and cloud properties. These measurements will be used to help determine how the ocean and atmosphere are influencing and being influenced by a changing climate. At the heart of the PACE mission is a broad spectrum moderate resolution (~1 km nadir) radiometer, called the Ocean Color Instrument (OCI). OCI will provide high spectral resolution (5 nm) from the UV to NIR (350 - 800 nm), with additional spectral bands in the NIR and SWIR to support atmospheric correction, and aerosol and cloud science. Never before has a U.S. space borne instrument measured across such a broad spectral range at such a fine spectral and spatial resolutions on a global scale. The added capability of OCI presents unique new opportunities for oceanic and atmospheric retrievals, but also new challenges, especially for atmospheric correction. These challenges are being met in a variety of creative ways. In addition to OCI, PACE may include a multi-spectral, multi-angle polarimeter that will enhance aerosol and cloud characterization, aid significantly in atmospheric correction for oceanic retrievals, and may offer new insight into characterization of oceanic hydrosols. With these advanced global remote sensing capabilities PACE is expected to: (1) Provide high quality observations for both basic science research, as well as applications; and (2) Extend the current time-series of climate quality data to enable detection of long-term trends.


    International Nuclear Information System (INIS)

    Lin Lin; Zhang Shuangnan; Kouveliotou, Chryssa; Baring, Matthew G.; Van der Horst, Alexander J.; Finger, Mark H.; Guiriec, Sylvain; Preece, Robert; Chaplin, Vandiver; Bhat, Narayan; Woods, Peter M.; Goegues, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Granot, Jonathan; Von Kienlin, Andreas; Watts, Anna L.; Wijers, Ralph A. M. J.; Gehrels, Neil; Harding, Alice


    We present our temporal and spectral analyses of 29 bursts from SGR J0501+4516, detected with the gamma-ray burst monitor on board the Fermi Gamma-ray Space Telescope during 13 days of the source's activation in 2008 (August 22- September 3). We find that the T 90 durations of the bursts can be fit with a log-normal distribution with a mean value of ∼123 ms. We also estimate for the first time event durations of soft gamma repeater (SGR) bursts in photon space (i.e., using their deconvolved spectra) and find that these are very similar to the T 90 values estimated in count space (following a log-normal distribution with a mean value of ∼124 ms). We fit the time-integrated spectra for each burst and the time-resolved spectra of the five brightest bursts with several models. We find that a single power law with an exponential cutoff model fits all 29 bursts well, while 18 of the events can also be fit with two blackbody functions. We expand on the physical interpretation of these two models and we compare their parameters and discuss their evolution. We show that the time-integrated and time-resolved spectra reveal that E peak decreases with energy flux (and fluence) to a minimum of ∼30 keV at F = 8.7 x 10 -6 erg cm -2 s -1 , increasing steadily afterward. Two more sources exhibit a similar trend: SGRs J1550-5418 and 1806-20. The isotropic luminosity, L iso , corresponding to these flux values is roughly similar for all sources (0.4-1.5 x 10 40 erg s -1 ).

  2. A review of gamma ray bursts

    CERN Document Server

    Rees, Martin J


    Gamma-ray bursts, an enigma for more than 25 years, are now coming into focus. They involve extraordinary power outputs, and highly relativistic dynamics. The 'trigger' involves stellar-mass compact objects. The most plausible progenitors, ranging from neutron star binary mergers to collapsars (sometimes called 'hypernovae') eventually lead to the formation of a black hole with a torus of hot neutron-density material around it, the extractable energy being up to 10 sup 5 sup 4 ergs. Magnetic fields may exceed 10 sup 1 sup 5 G and particles may be accelerated up to > or approx. 10 sup 2 sup 0 eV. Details of the afterglow may be easier to understand than the initial trigger. Bursts at very high redshift can be astronomically-important as probes of the distant universe.

  3. Burst Mode ASIC-Based Modem (United States)


    The NASA Lewis Research Center is sponsoring the Advanced Communication Technology Insertion (ACTION) for Commercial Space Applications program. The goal of the program is to expedite the development of new technology with a clear path towards productization and enhancing the competitiveness of U.S. manufacturers. The industry has made significant investment in developing ASIC-based modem technology for continuous-mode applications and has made investigations into East, reliable acquisition of burst-mode digital communication signals. With rapid advances in analog and digital communications ICs, it is expected that more functions will be integrated onto these parts in the near future. In addition custom ASIC's can also be developed to address the areas not covered by the other IC's. Using the commercial chips and custom ASIC's, lower-cost, compact, reliable, and high-performance modems can be built for demanding satellite communication application. This report outlines a frequency-hop burst modem design based on commercially available chips.

  4. Coherent combining pulse bursts in time domain (United States)

    Galvanauskas, Almantas


    A beam combining and pulse stacking technique is provided that enhances laser pulse energy by coherent stacking pulse bursts (i.e. non-periodic pulsed signals) in time domain. This energy enhancement is achieved by using various configurations of Fabry-Perot, Gires-Tournois and other types of resonant cavities, so that a multiple-pulse burst incident at either a single input or multiple inputs of the system produces an output with a solitary pulse, which contains the summed energy of the incident multiple pulses from all beams. This disclosure provides a substantial improvement over conventional coherent-combining methods in that it achieves very high pulse energies using a relatively small number of combined laser systems, thus providing with orders of magnitude reduction in system size, complexity, and cost compared to current combining approaches.

  5. Explaining fast radio bursts through Dicke's superradiance (United States)

    Houde, Martin; Mathews, Abhilash; Rajabi, Fereshteh


    Fast radio bursts (FRBs), characterized by strong bursts of radiation intensity at radio wavelengths lasting on the order of a millisecond, have yet to be firmly associated with a family, or families, of astronomical sources. It follows that despite the large number of proposed models, no well-defined physical process has been identified to explain this phenomenon. In this paper, we demonstrate how Dicke's superradiance, for which evidence has recently been found in the interstellar medium, can account for the characteristics associated with FRBs. Our analysis and modelling of previously detected FRBs suggest they could originate from regions in many ways similar to those known to harbour masers or megamasers, and result from the coherent radiation emanating from populations of molecules associated with large-scale entangled quantum mechanical states. We estimate this entanglement to involve as many as ˜1030 to ˜1032 molecules over distances spanning 100-1000 au.

  6. The impact of atrio-biventricular pacing on hemodynamics and left ventricular dyssynchrony compared with atrio-right ventricular pacing alone in the postoperative period after cardiac surgery. (United States)

    Cannesson, Maxime; Farhat, Fadi; Scarlata, Maria; Cassar, Emmanuel; Lehot, Jean-Jacques


    The aims of this study were to test the hypotheses that in the postoperative period after coronary artery bypass graft surgery (1) atrio-right ventricular (RA-RV) pacing induces a decrease in cardiac output compared with RA pacing alone and (2) atrio-biventricular (RA-BiV) pacing improves CO compared with RA-RV pacing. A prospective observational study. A single-center university hospital. Patients referred for coronary artery bypass graft surgery. Patients were studied during atrial, RA-RV, and RA-BiV pacing. Cardiac output (echocardiography) and left ventricular dyssynchrony were assessed at each step. RA-RV pacing induced a significant decrease in cardiac output (4.3 +/- 1.0 to 3.7 +/- 0.8 L/min, p < 0.01) and a significant increase in left ventricular dyssynchrony (13 +/- 12 to 80 +/- 25 milliseconds, p < 0.01). Biventricular pacing induced a significant increase in cardiac output (3.7 +/- 0.8 to 4.5 +/- 1.0 L/min, p < 0.01) and a significant decrease in left ventricular dyssynchrony compared with right ventricular pacing (80 +/- 25 to 21 +/- 16 milliseconds, p < 0.05). RA-BiV pacing improves cardiac output compared with RA-RV pacing in the postoperative period after coronary artery bypass graft surgery. This improvement is related to an improvement in left ventricular synchronicity.

  7. Digital Analysis of EBW Burst Waveforms

    Energy Technology Data Exchange (ETDEWEB)

    Lembke; J.R.; Tindall, A.L.; Latimer, C.


    A dual-channel digitizing capability has been established to digitally record and analyze electrical waveforms associated with exploding bridgewire (EBW) burst. The system is interfaced to a computer for data management and analysis. Programs for calibration and for analysis of voltage and current waveforms have been written. Error sources have been reduced to an acceptable level, and provisions have been made for generation of a waveform data library.

  8. Identifying crucial parameter correlations maintaining bursting activity.

    Directory of Open Access Journals (Sweden)

    Anca Doloc-Mihu


    Full Text Available Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA to each of these four groups. PCA identified a set of three maximal conductances (leak current, [Formula: see text]Leak; a persistent K current, [Formula: see text]K2; and of a persistent Na+ current, [Formula: see text]P that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of [Formula: see text]Leak, [Formula: see text]K2, and [Formula: see text]P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained.

  9. Thermonuclear model for γ-ray bursts

    International Nuclear Information System (INIS)

    Woosley, S.E.


    The evolution of magnetized neutron stars with field strengths of approx. 10 12 gauss that are accreting mass onto kilometer-sized polar regions at a rate of approx. 13 M 0 yr -1 is examined. Based on the results of one-dimensional calculations, one finds that stable hydrogen burning, mediated by the hot CNO-cycle, will lead to a critical helium mass in the range 10 20 to 10 22 g km -2 . Owing to the extreme degeneracy of the electron gas providing pressure support, helium burning occurs as a violent thermonuclear runaway which may propagate either as a convective deflagration (Type I burst) or as a detonation wave (Type II burst). Complete combustion of helium into 56 Ni releases from 10 38 to 10 40 erg km -2 and pushes hot plasma with β > 1 above the surface of the neutron star. Rapid expansion of the plasma channels a substantial fraction of the explosion energy into magnetic field stress. Spectral properties are expected to be complex with emission from both thermal and non-thermal processes. The hard γ-outburst of several seconds softens as the event proceeds and is followed by a period, typically of several minutes duration, of softer x-ray emission as the subsurface ashes of the thermonuclear explosion cool. In this model, most γ-ray bursts currently being observed are located at a distance of several hundred parsecs and should recur on a timescale of months to centuries with convective deflagrations (Type I bursts) being the more common variety. An explanation for Jacobson-like transients is also offered

  10. The cannonball model of gamma ray bursts

    CERN Document Server

    Dar, Arnon


    The cannonball model (CB) of gamma ray bursts (GRBs) is incredibly more successful than the standard blast-wave models (SM) of GRBs, which suffer from profound inadequacies and limited predictive power. The CB model is falsifiable in its hypothesis and results. Its predictions are summarized in simple analytical expressions, derived, in fair approximations, from first principles. It provides a good description on a universal basis of the properties of long-duration GRBs and of their afterglows (AGs).

  11. Adiabatic burst evaporation from bicontinuous nanoporous membranes (United States)

    Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk


    Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

  12. A Burst Chasing X-ray Polarimeter (United States)

    Hill, Joanne; Hill, Joe; Barthelmy, S.; Black, K.; Deines-Jones, P.; Jahoda, K.; Sakamoto, T.; Kaaret, P.; McConnell, M.; Bloser, P.; hide


    Tihs is a viewgraph presentation of a discussion of the X-ray Polarimeter. Gamma-ray bursts are one of the most powerful explosions in the universe and have been detected out to distances of almost 13 billion light years. The exact origin of these energetic explosions is still unknown but the resulting huge release of energy is thought to create a highly relativistic jet of material and a power-law distribution of electrons. There are several theories describing the origin of the prompt GRB emission that currently cannot be distinguished. Measurements of the linear polarization would provide unique and important constraints on the mechanisms thought to drive these powerful explosions. We present the design of a sensitive, and extremely versatile gamma-ray burst polarimeter. The instrument is a photoelectric polarimeter based on a time-projection chamber. The photoelectric time-projection technique combines high sensitivity with broad band-pass and is potentially the most powerful method between 2 and 100 keV where the photoelectric effect is the dominant interaction process We present measurements of polarized and unpolarized X-rays obtained with a prototype detector and describe the two mission concepts, the Gamma-Ray Burst Polarimeter (GRBP) for thc U S Naval Academy satellite MidSTAR-2, and thc Low Energy Polarimeter (LEP) onboard POET, a broadband polarimetry concept for a small explorer mission.

  13. Automatic Cloud Bursting under FermiCloud

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hao [Fermilab; Shangping, Ren [IIT; Garzoglio, Gabriele [Fermilab; Timm, Steven [Fermilab; Bernabeu, Gerard [Fermilab; Kim, Hyun Woo; Chadwick, Keith; Jang, Haengjin [KISTI, Daejeon; Noh, Seo-Young [KISTI, Daejeon


    Cloud computing is changing the infrastructure upon which scientific computing depends from supercomputers and distributed computing clusters to a more elastic cloud-based structure. The service-oriented focus and elasticity of clouds can not only facilitate technology needs of emerging business but also shorten response time and reduce operational costs of traditional scientific applications. Fermi National Accelerator Laboratory (Fermilab) is currently in the process of building its own private cloud, FermiCloud, which allows the existing grid infrastructure to use dynamically provisioned resources on FermiCloud to accommodate increased but dynamic computation demand from scientists in the domains of High Energy Physics (HEP) and other research areas. Cloud infrastructure also allows to increase a private cloud’s resource capacity through “bursting” by borrowing or renting resources from other community or commercial clouds when needed. This paper introduces a joint project on building a cloud federation to support HEP applications between Fermi National Accelerator Laboratory and Korea Institution of Science and Technology Information, with technical contributions from the Illinois Institute of Technology. In particular, this paper presents two recent accomplishments of the joint project: (a) cloud bursting automation and (b) load balancer. Automatic cloud bursting allows computer resources to be dynamically reconfigured to meet users’ demands. The load balance algorithm which the cloud bursting depends on decides when and where new resources need to be allocated. Our preliminary prototyping and experiments have shown promising success, yet, they also have opened new challenges to be studied


    Energy Technology Data Exchange (ETDEWEB)

    Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool, L3 5RF (United Kingdom); Harrison, R. [Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Japelj, J.; Gomboc, A. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Guidorzi, C. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, I-44122 Ferrara (Italy); Melandri, A., E-mail: [INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807, Merate (Italy)


    We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1–1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time.

  15. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk


    Full Text Available We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino emission. Accretion of matter powers the relativistic jets, responsible for the gamma ray prompt emission. The significant number density of neutrons in the disk and outflowing material will cause subsequent formation of heavier nuclei. We study the process of nucleosynthesis and its possible observational consequences. We also apply our scenario to the recent observation of the gravitational wave signal, detected on 14 September 2015 by the two Advanced LIGO detectors, and related to an inspiral and merger of a binary black hole system. A gamma ray burst that could possibly be related with the GW150914 event was observed by the Fermi satellite. It had a duration of about 1 s and appeared about 0.4 s after the gravitational-wave signal. We propose that a collapsing massive star and a black hole in a close binary could lead to the event. The gamma ray burst was powered by a weak neutrino flux produced in the star remnant’s matter. Low spin and kick velocity of the merged black hole are reproduced in our simulations. Coincident gravitational-wave emission originates from the merger of the collapsed core and the companion black hole.

  16. Content Aware Burst Assembly - Supporting Telesurgery and Telemedicine in Optical Burst Switching Networks

    Directory of Open Access Journals (Sweden)

    Henry Orosco


    Full Text Available The emerging Telemedicine and Telesurgery technologies allow patients to share medical experts remotely through communication networks. However, network bandwidth, network latency and jitter (variation of latency, are the obstacles to the widespread use of this technology remotely. Optical Burst Switching (OBS networks greatly expand network bandwidth in existing network infrastructure by utilizing multiple DWDM channels within a single fiber, enabling high bandwidth applications. However, the burst assembly process in OBS networks introduces latency and jitter, making it unsuitable for high bandwidth, latency sensitive applications such as telesurgery and telemedicine. In this paper, we propose a content aware burst assembly scheme which dynamically adjusts the burst assembly parameters based on the content being assembled. The proposed content aware burst assembly minimizes the latency and jitter within a video frame, as well as across the left-view and right-view frames for 3D vision generation. Simulation results have shown that the proposed scheme can effectively reduce the latency and jitter experienced by video streams, making OBS a promising candidate for supporting telesurgery and telemedicine applications.

  17. Secured Hash Based Burst Header Authentication Design for Optical Burst Switched Networks (United States)

    Balamurugan, A. M.; Sivasubramanian, A.; Parvathavarthini, B.


    The optical burst switching (OBS) is a promising technology that could meet the fast growing network demand. They are featured with the ability to meet the bandwidth requirement of applications that demand intensive bandwidth. OBS proves to be a satisfactory technology to tackle the huge bandwidth constraints, but suffers from security vulnerabilities. The objective of this proposed work is to design a faster and efficient burst header authentication algorithm for core nodes. There are two important key features in this work, viz., header encryption and authentication. Since the burst header is an important in optical burst switched network, it has to be encrypted; otherwise it is be prone to attack. The proposed MD5&RC4-4S based burst header authentication algorithm runs 20.75 ns faster than the conventional algorithms. The modification suggested in the proposed RC4-4S algorithm gives a better security and solves the correlation problems between the publicly known outputs during key generation phase. The modified MD5 recommended in this work provides 7.81 % better avalanche effect than the conventional algorithm. The device utilization result also shows the suitability of the proposed algorithm for header authentication in real time applications.

  18. Effect of age and performance on pacing of marathon runners

    Directory of Open Access Journals (Sweden)

    Nikolaidis PT


    Full Text Available Pantelis Theodoros Nikolaidis,1 Beat Knechtle2,3 1Exercise Physiology Laboratory, Attiki, Greece; 2Gesundheitszentrum St. Gallen, St. Gallen, 3Institute of Primary Care, University of Zurich, Zurich, Switzerland Abstract: Pacing strategies in marathon runners have previously been examined, especially with regard to age and performance level separately. However, less information about the age × performance interaction on pacing in age-group runners exists. The aim of the present study was to examine whether runners with similar race time and at different age differ for pacing. Data (women, n=117,595; men, n=180,487 from the “New York City Marathon” between 2006 and 2016 were analyzed. A between–within subjects analysis of variance showed a large main effect of split on race speed (p<0.001, η2=0.538 with the fastest speed in the 5–10 km split and the slowest in the 35–40 km. A small sex × split interaction on race speed was found (p<0.001, η2=0.035 with men showing larger increase in speed at 5 km and women at 25 km and 40 km (end spurt. An age-group × performance group interaction on Δspeed was shown for both sexes at 5 km, 10 km, 15 km, 20 km, 25 km, 30 km, 35 km, and 40 km (p<0.001, 0.001≤η2≤0.004, where athletes in older age-groups presented a relatively more even pace compared with athletes in younger age-groups, a trend that was more remarkable in the relatively slow performance groups. So far, the present study is the first one to observe an age × performance interaction on pacing; ie, older runners pace differently (smaller changes than younger runners with similar race time. These findings are of great practical interest for coaches working with marathon runners of different age, but similar race time. Keywords: running, master athlete, endurance, aerobic capacity, fatigue, gender, race time

  19. What Pace Is Best? Assessing Adults' Learning from Slideshows and Video (United States)

    Sage, Kara


    When acquiring information from a 2D platform, self-control and/or optimal pacing may help reduce cognitive load and enhance learning outcomes. In the present research, adults viewed novel action sequences via one of four learning media: (1) self-paced slideshows, where viewers advanced through slides at their own pace by clicking a mouse, (2)…

  20. Cardiac resynchronization as therapy for congestive cardiac failure in children dependent on chronic cardiac pacing.

    NARCIS (Netherlands)

    Beek, E. van; Backx, A.P.C.M.; Singh, S.K.


    Three patients with heart failure after chronic right ventricular apical pacing were treated with resynchronization. Biventricular pacing was used for two patients, and the other was treated with left univentricular pacing. In all patients, we observed a dramatic improvement of left ventricular

  1. Society for the Teaching of Psychology and the University of Wisconsin-Milwaukee: U-Pace (United States)

    EDUCAUSE, 2014


    The Society for the Teaching of Psychology and the University of Wisconsin-Milwaukee (UWM) partnered to disseminate U-Pace, a technology-enabled instructional model that promotes student success through deeper learning. UWM developed U-Pace in 2006 for an Introduction to Psychology course and, over time, evidence indicates that U-Pace not only…

  2. Predicting Successful Completion Using Student Delay Indicators in Undergraduate Self-Paced Online Courses (United States)

    Lim, Janine M.


    Self-paced online courses meet flexibility and learning needs of many students, but skepticism persists regarding the quality and the tendency for students to procrastinate in self-paced courses. Research is needed to understand procrastination and delay patterns of students in online self-paced courses to predict successful completion and…

  3. Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study

    NARCIS (Netherlands)

    Ritter, Philippe; Duray, Gabor Z.; Steinwender, Clemens; Soejima, Kyoko; Omar, Razali; Mont, Lluís; Boersma, Lucas V. A.; Knops, Reinoud E.; Chinitz, Larry; Zhang, Shu; Narasimhan, Calambur; Hummel, John; Lloyd, Michael; Simmers, Timothy Alexander; Voigt, Andrew; Laager, Verla; Stromberg, Kurt; Bonner, Matthew D.; Sheldon, Todd J.; Reynolds, Dwight; Kypta, Alexander; Vamos, Mate; Bordachar, Pierre; El Chami, Mikhael; Hussin, Azlan; Mont Girbau, Josep Lluís; Tolosana, José María; Morgan, John M.; Roberts, Paul; de Groot, Joris R.; Tjong, Fleur V. Y.; Sato, Toshiaki; Bongiorni, Maria Grazia; Soldati, Ezio; Augostini, Ralph; Love, Charles; Neuzil, Petr; Reddy, Vivek; Bracke, Frank A. L. E.; Sagi, Venkata; Lee, Scott; Gornick, Charles; Remole, Stephen; Sra, Jasbir; Nangia, Vikram; Shehata, Michael; Swerdlow, Charles; Schoenhard, John; Milstein, Simon; Saba, Samir; Bernabei, Matthew; Bansal, Sandeep; Stavrakis, Stavros


    Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker.

  4. Permanent pacing in infants and children: A single center experience in implantation and follow up

    Directory of Open Access Journals (Sweden)

    Rania Samir


    Conclusion: Permanent pacing in pediatric age group is relatively safe. However, there is substantial higher incidence of suboptimal pacing parameters and pacing system failures especially in younger and smaller children. Epicardial steroid eluting leads are comparable to endocardial steroid eluting leads in performance.

  5. Optimal pacing strategy : from theoretical modelling to reality in 1500-m speed skating

    NARCIS (Netherlands)

    Hettinga, F. J.; De Koning, J. J.; Schmidt, L. J. I.; Wind, N. A. C.; MacIntosh, B. R.; Foster, C.

    Purpose Athletes are trained to choose the pace which is perceived to be correct during a specific effort, such as the 1500-m speed skating competition. The purpose of the present study was to "override" self-paced (SP) performance by instructing athletes to execute a theoretically optimal pacing

  6. Effects of Modality and Pace on Achievement, Mental Effort, and Positive Affect in Multimedia Learning Environments (United States)

    Izmirli, Serkan; Kurt, Adile Askim


    The purpose of the study was to examine the effects of instruction given with different multimedia modalities (written text + animation or narration + animation) on the academic achievement, cognitive load, and positive affect in different paces (learner-paced or system-paced); 97 freshmen university students divided into four groups taught in…

  7. Type III Radio Burst Duration and SEP Events (United States)

    Gopalswamy, N.; Makela, P.; Xie, H.


    Long-duration (>15 min), low-frequency (SEP events of solar cycle 23. The Type III durations are distributed symmetrically at 1 MHz yielding a mean value of approximately 33 min (median = 32 min) for the large SEP events. When the SEP events with ground level enhancement (GLE,) are considered, the distribution is essentially unchanged (mean = 32 min, median = 30 min). To test the importance of type III bursts in indicating SEP events, we considered a set of six type III bursts from the same active region (AR 10588) whose durations fit the "long duration" criterion. We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with the type III bursts. The CMEs were of similar speeds and the flares are also of similar size and duration. All but one of the type III bursts was not associated with a type II burst in the metric or longer wavelength domains. The burst without type II burst also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1-MHz duration of the type III burst (28 rein) is near the median value of type III durations found for gradual SEP events and ground level enhancement (GLE) events. Yet, there was no sign of SEP events. On the other hand, two other type III bursts from the same active region had similar duration but accompanied by WAVES type 11 bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. This study suggests that the type III burst duration may not be a good indicator of an SEP event, consistent with the statistical study of Cliver and Ling (2009, ApJ ).

  8. The Pace and Shape of Senescence in Angiosperms

    DEFF Research Database (Denmark)

    Baudisch, Annette; Salguero-Gómez, Roberto; Jones, Owen


    1. Demographic senescence, the decay in fertility and increase in the risk of mortality with age, is one of the most striking phenomena in ecology and evolution. Comparative studies of senescence patterns of plants are scarce, and consequently, little is known about senescence and its determinants...... in the plant kingdom. 2. Senescence patterns of mortality can be classified by distinguishing between two metrics: pace and shape. The pace of mortality captures the speed at which life proceeds and can be measured by life expectancy, while the shape of mortality captures whether mortality increases...... (‘senescence’), decreases (‘negative senescence’) or remains constant over age (‘negligible senescence’). 3. We extract mortality trajectories from ComPADRe III, a data base that contains demographic information for several hundred plant species. We apply age-from-stage matrix decomposition methods to obtain...

  9. The pace of vocabulary growth helps predict later vocabulary skill (United States)

    Rowe, Meredith L.; Raudenbush, Stephen W.; Goldin-Meadow, Susan


    Children vary widely in the rate at which they acquire words—some start slow and speed up, others start fast and continue at a steady pace. Do early developmental variations of this sort help predict vocabulary skill just prior to kindergarten entry? This longitudinal study starts by examining important predictors (SES, parent input, child gesture) of vocabulary growth between 14 and 46 months (n=62), and then uses growth estimates to predict children's vocabulary at 54 months. Velocity and acceleration in vocabulary development at 30 months predicted later vocabulary, particularly for children from low socioeconomic backgrounds. Understanding the pace of early vocabulary growth thus improves our ability to predict school readiness, and may help identify children at risk for starting behind. PMID:22235920

  10. ELM pacing and the ITER operating window: mutual constraints (United States)

    Pacher, G. W.; Pacher, H. D.; Kukushkin, A. S.; Pitts, R. A.


    On ITER, one of the methods foreseen to reduce the energy loading due to edge localized modes (ELMs) on the divertor targets is the use of pellet injection to control the ELM frequency and amplitude of the energy losses at each ELM. However, the use of such pellet pacing introduces additional fuel throughput. This may constrict the burning plasma operating window through its influence on divertor plasma detachment, thus reducing the attainable alpha power. Consistent modelling of core, scrape-off layer, and divertor is used to document this effect. The result is a determination of the maximum attainable alpha power at the nominal pumping speed as a function of pacing pellet size and the maximum allowable pellet size as a function of ELM loss power fraction for which the reference operating window is not reduced.

  11. Organizational Learning: Keeping Pace with Change through Action Learning


    Yeadon-Lee, Annie


    In the current climate of economic ‘austerity’, organisational learning has increasingly gained importance, and a need for new ways of transferring learning has been identified. Organisational learning is seen as key to organisational success, ensuring both competitive advantage and organisational longevity. However, in order for organisations to keep pace with change they must not only strive to learn but also pay attention to how they might learn. A dominant view within the field of organis...

  12. Determination of inadvertent atrial capture during para-Hisian pacing. (United States)

    Obeyesekere, Manoj; Leong-Sit, Peter; Skanes, Allan; Krahn, Andrew; Yee, Raymond; Gula, Lorne J; Bennett, Matthew; Klein, George J


    Inadvertent capture of the atrium will lead to spurious results during para-Hisian pacing. We sought to establish whether the stimulation-to-atrial electrogram interval at the proximal coronary sinus (stim-PCS) or high right atrium (stim-HRA) could signal inadvertent atrial capture. Para-Hisian pacing with and without intentional atrial capture was performed in 31 patients. Stim-HRA and stim-PCS intervals were measured with atrial capture, His plus para-Hisian ventricular (H+V) capture, and para-Hisian ventricular (V) capture alone. The mean stim-HRA interval was significantly shorter with atrial capture (66 ± 18 ms) than with H+V (121 ± 27 ms, P capture alone (174 ± 38 ms, P capture (51 ± 16 ms) than with H+V (92 ± 22 ms, Pcapture alone (146 ± 33 ms, P capture. A stim-PCS >90 ms (stim-HRA >100 ms) was observed only in the absence of atrial capture. A stim-HRA of capture. Stim-HRA intervals of 75 to 97 ms and stim-PCS intervals of 65 to 88 ms were observed with either atrial, His, or para-Hisian ventricular capture without atrial capture. In this overlap zone, all patients demonstrated a stim-PCS or stim-HRA interval prolongation of at least 20 ms when the catheter was advanced to avoid deliberate atrial pacing. The QRS morphology was of limited value in distinguishing atrial capture due to concurrent ventricular or H+V capture, as observed in 20 of 31 (65%) patients. Stim-PCS and stim-HRA intervals can be used to monitor for inadvertent atrial capture during para-Hisian pacing. A stim-PCS 90 ms (or stim-HRA > 100 ms) were observed only with and without atrial capture, respectively, but there was significant overlap between these values. Deliberate atrial capture and loss of capture reliably identifies atrial capture regardless of intervals.

  13. [Permanent cardiac pacing in vasovagal syncope and carotid sinus syndrome]. (United States)

    Dupliakov, D V; Golovina, G A; Zemlianova, M E; Khokhlunov, S M; Poliakov, V P


    Vasovagal syncope and carotid sinus syndrome are common conditions in young and elderly people, respectively, mostly with benign prognosis. Nevertheless, severe or "malignant" syncopal attacks in some patients may be associated with life-threatening injury. Unfortunately, up to now almost all drug trials have failed to demonstrate any benefit in preventing syncope and interventional approach (pacemaker) may be appropriate. This article contains literature review and discussion of indications for pacing in vasovagal syncope and carotid sinus syndrome.

  14. Exploring the Pulse Structure of the Gamma-Ray Bursts from the Swift Burst Alert Telescop (United States)

    Martinez, Juan-Carlos; Team 1: Jon Hakkila, Amy Lien, Judith, Racusin, Team 2: Antonino Cucchiara, David Morris


    Gamma-ray bursts (GRBs) are one of the brightest and most intense explosions in our universe. For this project, we studied the shape of 400 single pulse GRBs using data gathered from Swift's Burst Alert Telescope (BAT). Hakkila et al. (2015) have discovered a mathematical Model that describes the GRB’s pulse shapes. Following the method in Hakkila et al. (2015), we fit GRB pulses with the Norris function and examined the residual in the fitting, to see whether the results are consistent with the one reported in Hakkila et al. (2015).

  15. Optimizing classroom instruction through self-paced learning prototype

    Directory of Open Access Journals (Sweden)

    Romiro Gordo Bautista


    Full Text Available This study investigated the learning impact of self-paced learning prototype in optimizing classroom instruction towards students’ learning in Chemistry. Two sections of 64 Laboratory High School students in Chemistry were used as subjects of the study. The Quasi-Experimental and Correlation Research Design was used in the study: a pre-test was conducted, scored and analyzed which served as the basis in determining the initial learning schema of the respondents. A questionnaire was adopted to find the learning motivation of the students in science. Using Pearson-r correlation, it was found out that there is a highly significant relationship between their internal drive and their academic performance. Moreover, a post-test was conducted after self-paced learning prototype was used in the development of select topics in their curricular plot. It was found out that the students who experienced the self-paced learning prototype performed better in their academic performance as evidenced by the difference of their mean post-test results. ANCOVA results on the post-test mean scores of the respondents were utilized in establishing the causal-effect of the learning prototype to the academic performance of the students in Chemistry. A highly significant effect on their academic performance (R-square value of 70.7% and significant interaction of the models to the experimental grouping and mental abilities of the respondents are concluded in the study.

  16. Unilateral Laryngeal Pacing System and Its Functional Evaluation

    Directory of Open Access Journals (Sweden)

    Taiping Zeng


    Full Text Available Goal. To establish a reliable instrumental system for synchronized reactivation of a unilaterally paralyzed vocal fold and evaluate its functional feasibility. Methods. Unilateral vocal fold paralysis model was induced by destruction of the left recurrent laryngeal nerve (RLN in anesthetized dogs. With a micro controller-based electronic system, electromyography (EMG signals from cricothyroid (CT muscle on the ipsilateral side were recorded and used to trigger pacing of paralyzed vocalis muscles. The dynamic movement of vocal folds was continuously monitored using an endoscope, and the opening and closing of the glottis were quantified with customized imaging processing software. Results. The recorded video images showed that left side vocal fold was obviously paralyzed after destructing the RLN. Using the pacing system with feedback triggering EMG signals from the ipsilateral CT muscle, the paralyzed vocal fold was successfully reactivated, and its movement was shown to be synchronized with the healthy side. Significance. The developed unilateral laryngeal pacing system triggered by EMG from the ipsilateral side CT muscle could be successfully used in unilateral vocal fold paralysis with the advantage of avoiding disturbance to the healthy side muscles.

  17. Combined obliquity and precession pacing of late Pleistocene deglaciations. (United States)

    Huybers, Peter


    Milankovitch proposed that Earth resides in an interglacial state when its spin axis both tilts to a high obliquity and precesses to align the Northern Hemisphere summer with Earth's nearest approach to the Sun. This general concept has been elaborated into hypotheses that precession, obliquity or combinations of both could pace deglaciations during the late Pleistocene. Earlier tests have shown that obliquity paces the late Pleistocene glacial cycles but have been inconclusive with regard to precession, whose shorter period of about 20,000 years makes phasing more sensitive to timing errors. No quantitative test has provided firm evidence for a dual effect. Here I show that both obliquity and precession pace late Pleistocene glacial cycles. Deficiencies in time control that have long stymied efforts to establish orbital effects on deglaciation are overcome using a new statistical test that focuses on maxima in orbital forcing. The results are fully consistent with Milankovitch's proposal but also admit the possibility that long Southern Hemisphere summers contribute to deglaciation.

  18. Factors affecting the regulation of pacing: current perspectives

    Directory of Open Access Journals (Sweden)

    Mauger AR


    Full Text Available Alexis R Mauger Endurance Research Group, School of Sport and Exercise Sciences, Faculty of Science, University of Kent, Chatham, UK Abstract: During prolonged dynamic and rhythmic exercise, muscular pain and discomfort arises as a result of an increased concentration of deleterious metabolites. Sensed by peripheral nociceptors and transmitted via afferent feedback to the brain, this provides important information regarding the physiological state of the muscle. These sensations ultimately contribute to what is termed "exercise-induced pain". Despite being well recognized by athletes and coaches, and suggested to be integral to exercise performance, this construct has largely escaped attention in experimental work. This perspective article highlights the current understanding of pacing in endurance performance, and the causes of exercise-induced pain. A new perspective is described, which proposes how exercise-induced pain may be a contributing factor in helping individuals to regulate their work rate during exercise and thus provides an important construct in pacing. Keywords: pain, exercise-induced pain, discomfort, exercise performance, self-paced

  19. PWR clad ballooning: The effect of circumferential clad temperature variations on the burst strain/burst temperature relationship

    International Nuclear Information System (INIS)

    Barlow, P.


    By experiment, it has been shown by other workers that there is a reduction in the creep ductility of Zircaloy 4 in the α+β phase transition region. Results from single rod burst tests also show a reduction in burst strain in the α+β phase region. In this report it is shown theoretically that for single rod burst tests in the presence of circumferential temperature gradients, the temperature dependence of the mean burst strain is not determined by temperature variations in creep ductility, but is governed by the temperature sensitivity of the creep strain rate, which is shown to be a maximum in the α+β phase transition region. To demonstrate this effect, the mean clad strain at burst was calculated for creep straining at different temperature levels in the α, α+β and β phase regions. Cross-pin temperature gradients were applied which produced strain variations around the clad which were greatest in the α+β phase region. The mean strain at burst was determined using a maximum local burst strain (i.e. a creep ductility) which is independent of temperature. By assuming cross-pin temperature gradients which are typical of those observed during burst tests, then the calculated mean burst strain/burst temperature relationship gave good agreement with experiment. The calculations also show that when circumferential temperature differences are present, the calculated mean strain at burst is not sensitive to variations in the magnitude of the assumed creep ductility. This reduces the importance of the assumed burst criterion in the calculations. Hence a temperature independent creep ductility (e.g. 100% local strain) is adequate as a burst criterion for calculations under PWR LOCA conditions. (author)

  20. Cardiac resynchronization therapy is appropriate for all patients requiring chronic right ventricular pacing: the con perspective. (United States)

    Daoud, Emile G


    There has been compelling evidence for the use of biventricular (BiV) pacing to reduce mortality and heart failure (HF) hospitalization in patients with HF symptoms, depressed ejection fraction (EF), and a broad QRS. Cardiac resynchronization therapy (CRT) provides benefit for patients with depressed EF and minimal HF symptoms. Although data from CRT trials are compelling, clinical evidence to recommend BiV pacing to all patients who require a high degree of right ventricular (RV) pacing are lacking. This article summarizes the relevant studies demonstrating that BiV pacing is not appropriate therapy for all patients who require chronic RV pacing. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Cardiac resynchronization therapy is appropriate for all patients requiring chronic right ventricular pacing: the pro perspective. (United States)

    Herweg, Bengt; Singh, Robin; Barold, S Serge


    Long-term right ventricular pacing has deleterious effects on the left ventricle (LV). The risk of pacemaker-induced cardiomyopathy (PICM) seems to be lower in patients with a normal LV ejection fraction (LVEF). Patients developing PICM respond favorably to a cardiac resynchronization therapy upgrade, suggesting that the dysfunction is partially reversible. Biventricular pacing has emerged as a treatment and/or prevention of PICM. Cumulative pacing greater than 40% of the time is considered the most important risk factor for PICM. No organizational guidelines exist for preventive biventricular pacing. The decision to pursue biventricular pacing should be individualized. Published by Elsevier Inc.

  2. Emergent synchronous bursting of oxytocin neuronal network.

    Directory of Open Access Journals (Sweden)

    Enrico Rossoni


    Full Text Available When young suckle, they are rewarded intermittently with a let-down of milk that results from reflex secretion of the hormone oxytocin; without oxytocin, newly born young will die unless they are fostered. Oxytocin is made by magnocellular hypothalamic neurons, and is secreted from their nerve endings in the pituitary in response to action potentials (spikes that are generated in the cell bodies and which are propagated down their axons to the nerve endings. Normally, oxytocin cells discharge asynchronously at 1-3 spikes/s, but during suckling, every 5 min or so, each discharges a brief, intense burst of spikes that release a pulse of oxytocin into the circulation. This reflex was the first, and is perhaps the best, example of a physiological role for peptide-mediated communication within the brain: it is coordinated by the release of oxytocin from the dendrites of oxytocin cells; it can be facilitated by injection of tiny amounts of oxytocin into the hypothalamus, and it can be blocked by injection of tiny amounts of oxytocin antagonist. Here we show how synchronized bursting can arise in a neuronal network model that incorporates basic observations of the physiology of oxytocin cells. In our model, bursting is an emergent behaviour of a complex system, involving both positive and negative feedbacks, between many sparsely connected cells. The oxytocin cells are regulated by independent afferent inputs, but they interact by local release of oxytocin and endocannabinoids. Oxytocin released from the dendrites of these cells has a positive-feedback effect, while endocannabinoids have an inhibitory effect by suppressing the afferent input to the cells.

  3. Infrared and X-ray bursts from the rapid burster

    International Nuclear Information System (INIS)

    Apparao, K.M.V.; Chitre, S.M.


    Studies on sudden bursts from the cosmic X-ray sources are reported. The processes occuring from the rise in luminosity of an x-ray source to its collapse are described. Records of the x-ray burst from the globular cluster NGC 6624 and the 'Rapid Burster' are shown. The Infra-red bursts from the Rapid Burster are also explained. (A.K.)

  4. Physical characterization of the Skua fast burst assembly

    International Nuclear Information System (INIS)

    Paternoster, R.; Bounds, J.; Sanchez, R.; Miko, D.


    In this paper we discuss the system design and ongoing efforts to characterize the machine physics and operating properties of the Skua fast burst assembly. The machine is currently operating up to prompt critical while we await approval for super-prompt burst operations. Efforts have centered on characterizing neutron kinetic properties, comparing calculated and measured temperature coefficients and power distributions, improving the burst reproducibility, examining the site-wide dose characteristics, and fitting the machine with cooling and filtration systems

  5. The velocities of type II solar radio bursts

    International Nuclear Information System (INIS)

    Tlamicha, A.; Karlicky, M.


    A list is presented of type II radio bursts identified at Ondrejov between January 1973 and December 1974 in the frequency range of the dynamic spectrum 70 to 810 MHz. The velocities of shock waves in the individual cases of type II bursts are given using the fourfold Newkirk model. Some problems associated with type II radio bursts and with the propagation of the shock wave into the interplanetary space and into the region of the Earth are also discussed. (author)

  6. Detecting Pipe Bursts Using Heuristic and CUSUM Methods


    Bakker, M.; Jung, D.; Vreeburg, J.; van de Roer, M.; Lansey, K.; Rietveld, L.


    Pipe bursts in a drinking water distribution system lead to water losses, interruption of supply, and damage to streets and houses due to the uncontrolled water flow. To minimize the negative consequences of pipe bursts, an early detection is necessary. This paper describes a heuristic burst detection method, which continuously compares forecasted and measured values of the water demand. The forecasts of the water demand were generated by an adaptive water demand forecasting model. To test th...

  7. Self-regulation of turbulence bursts and transport barriers

    International Nuclear Information System (INIS)

    Floriani, E; Ciraolo, G; Ghendrih, Ph; Sarazin, Y; Lima, R


    The interplay between turbulent bursts and transport barriers is analyzed with a simplified model of interchange turbulence in magnetically confined plasmas. The turbulent bursts spread into the transport barriers and, depending on the competing magnitude of the burst and stopping capability of the barrier, can burn through. Simulations of two models of transport barriers are presented: a hard barrier where interchange turbulence modes are stable in a prescribed region and a soft barrier with external plasma biasing. The response of the transport barriers to the non-linear perturbations of the turbulent bursts, addressed in a predator–prey approach, indicates that the barriers monitor an amplification factor of the turbulent bursts, with amplification smaller than one for most bursts and, in some cases, amplification factors that can significantly exceed unity. The weak barriers in corrugated profiles and magnetic structures, as well as the standard barriers, are characterized by these transmission properties, which then regulate the turbulent burst transport properties. The interplays of barriers and turbulent bursts are modeled as competing stochastic processes. For different classes of the probability density function (PDF) of these processes, one can predict the heavy tail properties of the bursts downstream from the barrier, either exponential for a leaky barrier, or with power laws for a tight barrier. The intrinsic probing of the transport barriers by the turbulent bursts thus gives access to the properties of the barriers. The main stochastic variables are the barrier width and the spreading distance of the turbulent bursts within the barrier, together with their level of correlation. One finds that in the case of a barrier with volumetric losses, such as radiation or particle losses as addressed in our present simulations, the stochastic model predicts a leaky behavior with an exponential PDF of escaping turbulent bursts in agreement with the simulation

  8. Burst Alert Robotic Telescope and Optical Afterglows

    Czech Academy of Sciences Publication Activity Database

    Nekola, Martin; Hudec, René; Jelínek, M.; Kubánek, P.; Polášek, Cyril; Štrobl, Jan


    Roč. 18, 3/4 (2009), s. 374-378 ISSN 1392-0049. [INTEGRAL/BART workshop 2009. Karlovy Vary, 26.03.2009-29.03.2009] R&D Projects: GA ČR GA205/08/1207 Grant - others:ESA(XE) ESA-PECS project No. 98023; Spanish Ministry of Education and Science(ES) AP2003-1407 Institutional research plan: CEZ:AV0Z10030501 Keywords : gamma rays bursts, * observations * robotic telescopes Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.032, year: 2009

  9. Bursting frequency prediction in turbulent boundary layers

    Energy Technology Data Exchange (ETDEWEB)



    The frequencies of the bursting events associated with the streamwise coherent structures of spatially developing incompressible turbulent boundary layers were predicted using global numerical solution of the Orr-Sommerfeld and the vertical vorticity equations of hydrodynamic stability problems. The structures were modeled as wavelike disturbances associated with the turbulent mean flow. The global method developed here involves the use of second and fourth order accurate finite difference formula for the differential equations as well as the boundary conditions. An automated prediction tool, BURFIT, was developed. The predicted resonance frequencies were found to agree very well with previous results using a local shooting technique and measured data.

  10. Prompt Emission Observations of Swift BAT Bursts (United States)

    Barthelmy, Scott


    We review the prompt emission properties of Swift BAT gamma-ray bursts (GRBs). We present the global properties of BAT GRBs based on their spectral and temporal characteristics. The BAT T90 and T50 durations peak at 80 and 20 s, respectively. The peak energy (Epeak) of about 60% of BAT GRBs is very likely to be less than 1.00 keV. We also present the BAT characteristics of GRBs with soft spectra, so called Xray flashes (XRFs). We will compare the BAT GRBs and XRFs parameter distribution to the other missions.

  11. Decay time of type III solar bursts

    International Nuclear Information System (INIS)

    Alvarez, H.; Haddock, F.T.


    Sixty-four Type III bursts that drifted to frequencies below 600 kHz between March 1968 and February 1970 were analyzed. Decay times were measured and combined with published data ranging up to about 200 MHz. By fitting power functions to the computed and observed decay times, and using the local plasma hypothesis, it was found that the ratio rho of computed to observed values varies with radiocentric radial distance according to a power function rho = 3r 0 . 7 . (U.S.)

  12. Burst-Mode Asynchronous Controllers on FPGA

    Directory of Open Access Journals (Sweden)

    Duarte L. Oliveira


    Full Text Available FPGAs have been mainly used to design synchronous circuits. Asynchronous design on FPGAs is difficult because the resulting circuit may suffer from hazard problems. We propose a method that implements a popular class of asynchronous circuits, known as burst mode, on FPGAs based on look-up table architectures. We present two conditions that, if satisfied, guarantee essential hazard-free implementation on any LUT-based FPGA. By doing that, besides all the intrinsic advantages of asynchronous over synchronous circuits, they also take advantage of the shorter design time and lower cost associated with FPGA designs.

  13. Self-paced intermittent-sprint performance and pacing strategies following respective pre-cooling and heating. (United States)

    Skein, Melissa; Duffield, Rob; Cannon, Jack; Marino, Frank E


    This study examined the effects of pre-exercise cooling and heating on neuromuscular function, pacing and intermittent-sprint performance in the heat. Ten male, team sport athletes completed three randomized, counterbalanced conditions including a thermo-neutral environment (CONT), whole body submersion in an ice bath (ICE) and passive heating in a hot environment (HEAT) before 50 min of intermittent-sprint exercise (ISE) in the heat (31 + 1°C). Exercise involved repeated 15 m maximal sprints and self-paced exercise of varying intensities. Performance was measured by sprint times and distance covered during self-paced exercise. Maximal isometric contractions were performed to determine the maximal voluntary torque (MVT), activation (VA) and contractile properties. Physiological measures included heart rate (HR), core (T (core)) and skin (T (skin)) temperatures, capillary blood and perceptual ratings. Mean sprint times were slower during ICE compared to HEAT (P HEAT in 31-40 min compared to CONT, and 41-50 min compared to ICE (P HEAT. VA was reduced post-intervention in HEAT compared to CONT and ICE, and post-exercise compared to ICE (P HEAT (P HEAT conditions compared to CONT. However, initial sprint performance was slowed by pre-cooling, with improvements following passive heating possibly due to altered contractile properties. Conversely, pre-cooling improved exercise intensities, whilst HEAT resulted in greater declines in muscle recruitment and ensuing distance covered.

  14. The Second SWIFT Burst Alert Telescope (BAT) Gamma-Ray Burst Catalog (United States)

    Sakamoto, T.; Barthelmy, S. D.; Baumgartner, W. H.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; hide


    We present the second Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts. (GRBs), which contains 476 bursts detected by the BAT between 2004 December 19 and 2009 December 21. This catalog (hereafter the BAT2 catalog) presents burst trigger time, location, 90% error radius, duration, fluence, peak flux, time-averaged spectral parameters and time-resolved spectral parameters measured by the BAT. In the correlation study of various observed parameters extracted from the BAT prompt emission data, we distinguish among long-duration GRBs (L-GRBs), short-duration GRBs (S-GRBs), and short-duration GRBs with extended emission (S-GRBs with E.E.) to investigate differences in the prompt emission properties. The fraction of L-GRBs, S-GRBs and S-GRBs with E.E. in the catalog are 89%, 8% and 2% respectively. We compare the BAT prompt emission properties with the BATSE, BeppoSAX and HETE-2 GRB samples.. We also correlate the observed prompt emission properties with the redshifts for the GRBs with known redshift. The BAT T(sub 90) and T(sub 50) durations peak at 70 s and 30 s, respectively. We confirm that the spectra of the BAT S-GRBs are generally harder than those of the L-GRBs.

  15. Limits of the memory coefficient in measuring correlated bursts (United States)

    Jo, Hang-Hyun; Hiraoka, Takayuki


    Temporal inhomogeneities in event sequences of natural and social phenomena have been characterized in terms of interevent times and correlations between interevent times. The inhomogeneities of interevent times have been extensively studied, while the correlations between interevent times, often called correlated bursts, are far from being fully understood. For measuring the correlated bursts, two relevant approaches were suggested, i.e., memory coefficient and burst size distribution. Here a burst size denotes the number of events in a bursty train detected for a given time window. Empirical analyses have revealed that the larger memory coefficient tends to be associated with the heavier tail of the burst size distribution. In particular, empirical findings in human activities appear inconsistent, such that the memory coefficient is close to 0, while burst size distributions follow a power law. In order to comprehend these observations, by assuming the conditional independence between consecutive interevent times, we derive the analytical form of the memory coefficient as a function of parameters describing interevent time and burst size distributions. Our analytical result can explain the general tendency of the larger memory coefficient being associated with the heavier tail of burst size distribution. We also find that the apparently inconsistent observations in human activities are compatible with each other, indicating that the memory coefficient has limits to measure the correlated bursts.

  16. Frequency of fast, narrow γ-ray bursts

    International Nuclear Information System (INIS)

    Norris, J.P.; Maryland Univ., College Park; Cline, T.L.; Desai, U.D.; Teegarden, B.J.


    The paper describes the existence of two γ-ray burst populations detected by the ISEE-3 experiment. Data from the distribution of 123 Venera 13 and 14 events (60 detected by both spacecraft) also suggests two γ-ray burst populations in each experiment sample, the domains separated with a minimum near 1 or 2 s. The authors point out that the results of the Goddard ISEE-3 γ-ray burst spectrometer actually enhance the appearance of two burst populations suggested in the Venera data. (author)

  17. Observations of cosmic gamma ray bursts with WATCH on EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, N.; Castro-Tirado, A. J.


    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy......, trapped particle streams. These background events may simulate the count rate increases characteristic of cosmic gamma bursts. For 12 of the detected events, their true cosmic nature have been confirmed through consistent localizations of the burst sources based on several independent WATCH data sets...

  18. Burst-Compression And -Expansion For TDMA Communication (United States)

    Budinger, James M.


    Burst-compression and -expansion technique enables interconnection of users transmitting and receiving data at rates asynchronous with respect to clocks within ground terminals of satellite-switched, time-division-multiple-access (TDMA) communication network. Matrix switch aboard satellite routes bursts of data from source users received on uplink antennas to downlink antennas illuminating ground areas containing destination users. TDMA ground terminal compresses streams of data from source users into rapid bursts for transmission and reexpands bursts of received data into slower streams of data for delivery to destination users. Greater flexibility in interconnecting widely dispersed users achieved by use of hopping beams.

  19. Study on cosmic gamma bursts in the ''KONUS'' experiment

    International Nuclear Information System (INIS)

    Mazets, E.P.; Golenetskij, S.V.; Il'inskij, V.N.; Panov, V.N.; Aptekar', R.L.; Gur'yan, Yu.A.; Sokolov, I.A.; Sokolova, Z.Ya.; Kharitonova, T.V.


    Made are the investigations of cosmic gamma bursts with the help of the ''Konus'' apparatus, positioned on the ''Venera 11'' and ''Venera 12'' automatic interplanetary stations. 37 gamma bursts have been recorded in the energy range from 50 to 150 keV during the observation period from September to December 1978. Time profiles of bursts on 4, 9 and 24.11.1978 are presented. For the most events the time of burst increase and decrease constitute parts and units of seconds. Differential energy spectra are measured for all recorded bursts. In many cases the spectrum shape is similar to the grade one with the 1.5-2.3 index. In a graphical form built up are the integral distributions of gamma bursts appearence frequency in dependence on their intensity and maximum capacity in the burst peak. Galaxy coordinates of the 17-teen bursts, for which a simple localization is possible, are put on the celestial sphere map. The type of the integral distributions and the source distribution about the celestial sphere show that the gamma burst sources are whithin the Galaxy

  20. Star bursts and giant HII regions

    International Nuclear Information System (INIS)

    Pagel, B.E.J.


    Massive star formation bursts occur in a variety of galactic environments and can temporarily dominate the light output of a galaxy even when a relatively small proportion of its mass is involved. Inferences about their ages, the IMF and its dependence on chemical composition are still somewhat wobbly owing to an excess of unknowns, but certain things can be deduced from emission spectra of associated H II regions when due regard is paid to the effects of chemical composition and ionization parameter: In particular, largest ionization parameters and effective temperatures of exciting stars, at any given oxygen abundance, are anti-correlated with the abundance, and the second effect suggests an increasing proportion of more massive stars at lower abundances, although this is not yet satisfactorily quantified. A new blue compact galaxies could be very young, but it is equally possible that there is an older population of low surface brightness. Some giant H II regions may be self-polluted with nitrogen and helium due to winds from massive stars in the associated burst. (orig.)

  1. Bouncing and bursting in a wedge (United States)

    Reyssat, Etienne; Cohen, Caroline; Quere, David


    Placed into an inhomogeneous confined medium, non-wetting drops tend to be expelled from the tightest regions, where their contact with the walls would be maximized. They preferentially explore more open areas which are favorable from the point of view of capillary energy. Following this principle, one may thus use the geometry of confined environments to control fluid droplets in various ways : displacing, filtering, fragmenting... In this communication, we present experimental results on the dynamics of Leidenfrost drops launched into a wedge formed by two quasi-horizontal glass plates. Influenced by the gradient of confinement, these non-wetting liquid pucks approach the apex of the wedge to a minimal distance where they bounce back. At higher impact velocity, we observe that drops tend to penetrate deeper into the wedge but often burst into a large number of small fragments. We also discuss ways to control the deviation of droplets from their initial trajectory. We propose scaling law analyses to explain the characteristics of the observed bouncing and bursting phenomena.

  2. Are 'negative bursts' due to absorption

    International Nuclear Information System (INIS)

    Sawyer, C.


    Optical activity near the time of two microwave negative bursts is distinctive enough to demonstrate a real relation, but does not occur simultaneously with the radio events. Such a loose association between microwave flux decreases and Hα prominence or filament activity is typical of a sample of 23 negative bursts. A model of a microwave occulting cloud differs from that of an Hα absorber: the Hα dark flocculus is relatively low, dense and compact: the microwave occulter is higher in the corona, larger, and more completely ionized. The two types of absorption are not expected to been seen simultaneously, although they could be separate phases of an ejection of chromospheric material into the corona. The association of microwave decreases with Hα activity in some cases, and their usual non-simultaneity, is consistent with interpretation of the decrease as absorption, but it does not rule out alternative interpretation such as an intrinsic change in the emission of the microwave source. The location of decrease-associated activity has a suggestive, though not statistically significant, bias toward east limb that leads one toward an absorption interpretation, with asymmetry introduced by a tendency for ejected material to move from the leading part of an active region toward the following part, agreeing with Liska's observation of asymmetry in the line-of-sight velocities of prominences. (Auth.)

  3. Q-Burst Origins in Africa (United States)

    Boldi, R.; Hobara, Y.; Yamashita, K.; Hayakawa, M.; Satori, G.; Bor, J.; Lyons, W. A.; Nelson, T.; Russell, B.; Williams, E.


    The generation of electromagnetic transient signatures in the SR frequency range (Q-bursts) from the energetic lightning originating in Africa were intensively studied during the AMMA (African Monsoon Multidisciplinary Analysis) field program centered on Niamey, Niger in 2006. During this wet season many active westward- moving MCSs were observed by the MIT C-band Doppler radar. The MCSs exhibited a gust front, a leading squall line and a large spatially-extended (100-200 km) stratiform region that often passed over the observation site. Many transient events were recorded in association with local lightning both with a slow antenna and a DC electric field mill installed near the radar. During the gust front and squall line traverse, the majority of lightning exhibited normal polarity. A remarkable transition of polarity is observed once the radar site is under the stratiform region and a pronounced radar bright band has had time to develop. The majority of the ground flashes then exhibit a positive polarity (positive ground flash). In particular, very intense positive ground flashes (often topped with spider lightning structure) are registered when the radar "hbright band"h is most strongly developed. These positive flashes exhibit a large DC field change in comparison to ones observed during the earlier squall line passage. Video observations of nighttime events support the existence of the lateral extensive spider lightning. Daytime events exhibit thunder durations of a few minutes. ELF Q-bursts were recorded at MIT's Schumann resonance station in Rhode Island U.S.A. (about 8 Mm distance from Niamey) associated with several large well-established positive ground flashes observed locally near Niamey. The event identification is made by accurate GPS timing and arrival direction of the waves. The onset times of the Q-burst are in good agreement with the electric field measurement near Niamey. The arrival directions of the waves are also in good agreement assuming

  4. Successful pacing using a batteryless sunlight-powered pacemaker. (United States)

    Haeberlin, Andreas; Zurbuchen, Adrian; Schaerer, Jakob; Wagner, Joerg; Walpen, Sébastien; Huber, Christoph; Haeberlin, Heinrich; Fuhrer, Juerg; Vogel, Rolf


    Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker. We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed. Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email:

  5. Biventricular / Left Ventricular Pacing in Hypertrophic Obstructive Cardiomyopathy: An Overview

    Directory of Open Access Journals (Sweden)

    Radu Vatasescu, MD


    Full Text Available Hypertrophic cardiomyopathy (HCM is an autosomal dominant inherited genetic disease characterized by compensatory pathological left ventricle (LV hypertrophy due to sarcomere dysfunction. In an important proportion of patients with HCM, the site and extent of cardiac hypertrophy results in severe obstruction to LV outflow tract (LVOT, contributing to disabling symptoms and increasing the risk of sudden cardiac death (SCD. In patients with progressive and/or refractory symptoms despite optimal pharmacological treatment, invasive therapies that diminish or abolish LVOT obstruction relieve heart failure-related symptoms, improve quality of life and could be associated with long-term survival similar to that observed in the general population. The gold standard in this respect is surgical septal myectomy, which might be supplementary associated with a reduction in SCD. Percutaneous techniques, particularly alcohol septal ablation (ASA and more recently radiofrequency (RF septal ablation, can achieve LVOT gradient reduction and symptomatic benefit in a large proportion of HOCM patients at the cost of a supposedly limited septal myocardial necrosis and a 10-20% risk of chronic atrioventricular block. After an initial period of enthusiasm, standard DDD pacing failed to show in randomized trials significant LVOT gradient reductions and objective improvement in exercise capacity. However, case reports and recent small pilot studies suggested that atrial synchronous LV or biventricular (biV pacing significantly reduce LVOT obstruction and improve symptoms (acutely as well as long-term in a large proportion of severely symptomatic HOCM patients not suitable to other gradient reduction therapies. Moreover, biV/LV pacing in HOCM seems to be associated with significant LV reverse remodelling.

  6. Acute impact of pacing at different cardiac sites on left ventricular rotation and twist in dogs.

    Directory of Open Access Journals (Sweden)

    Zhi-Wen Zhou

    Full Text Available We evaluated the acute impact of different cardiac pacing sites on two-dimensional speckle-tracking echocardiography (STE derived left ventricular (LV rotation and twist in healthy dogs.Twelve dogs were used in this study. The steerable pacing electrodes were positioned into right heart through the superior or inferior vena cava, into LV through aorta across the aortic valve. The steerable pacing electrodes were positioned individually in the right atrium (RA, right ventricular apex (RVA, RV outflow tract (RVOT, His bundle (HB, LV apex (LVA and LV high septum (LVS, individual pacing mode was applied at 10 minutes interval for at least 5 minutes from each position under fluoroscopy and ultrasound guidance and at stabilized hemodynamic conditions. LV short-axis images at the apical and basal levels were obtained during sinus rhythm and pacing. Offline STE analysis was performed. Rotation, twist, time to peak rotation (TPR, time to peak twist (TPT, and apical-basal rotation delay (rotational synchronization index, RSI values were compared at various conditions. LV pressure was monitored simultaneously.Anesthetic death occurred in 1 dog, and another dog was excluded because of bad imaging quality. Data from 10 dogs were analyzed. RVA, RVOT, HB, LVA, LVS, RARV (RA+RVA pacing resulted in significantly reduced apical and basal rotation and twist, significantly prolonged apical TPR, TPT and RSI compared to pre-pacing and RA pacing (all P<0.05. The apical and basal rotation and twist values were significantly higher during HB pacing than during pacing at ventricular sites (all P<0.05, except basal rotation at RVA pacing. The apical TPR during HB pacing was significantly shorter than during RVOT and RVA pacing (both P<0.05. The LV end systolic pressure (LVESP was significantly lower during ventricular pacing than during pre-pacing and RA pacing.Our results show that RA and HB pacing results in less acute reduction on LV twist, rotation and LVESP compared

  7. Pajarito Aerosol Couplings to Ecosystems (PACE) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, M [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Laboratory (LANL) worked on the Pajarito Aerosol Couplings to Ecosystems (PACE) intensive operational period (IOP). PACE’s primary goal was to demonstrate routine Mobile Aerosol Observing System (MAOS) field operations and improve instrumental and operational performance. LANL operated the instruments efficiently and effectively with remote guidance by the instrument mentors. This was the first time a complex suite of instruments had been operated under the ARM model and it proved to be a very successful and cost-effective model to build upon.

  8. Structural analysis of cell wall polysaccharides using PACE

    Energy Technology Data Exchange (ETDEWEB)

    Mortimer, Jennifer C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Institute


    The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. Many techniques to characterize polysaccharide structure are complicated, requiring expensive equipment and specialized operators e.g. NMR, MALDI-MS. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al. 2002). Whilst the method here describes xylan analysis, it can be applied (by use of the appropriate glycosyl hydrolase) to any cell wall polysaccharide.

  9. Ecuador steps up pace of oil development activity

    International Nuclear Information System (INIS)



    This paper reports that oil companies operating in Ecuador plan to quicken the pace of oil development this year. After delays in 1991, companies plan a series of projects to develop reserves discovered the past 3 years estimated at more than 600 million bbl. Oil and Gas Journal estimated Ecuador's proved crude reserves at 1.55 billion bbl as of Jan. 1, 1992. The development push is part of a larger effort needed to ensure Ecuador's status as an oil exporter into the next century. Ecuador is the smallest crude oil producer and exporter in the Organization of Petroleum Exporting Countries

  10. Electrical Stimulation of the Heart: Pacing, Arrhythmias, and Defibrillation (United States)

    Roth, Bradley J.


    Electrical stimulation of the heart underlies cardiac pacing and defibrillation. The "bidomain model" describes the anisotropic electrical properties of cardiac tissue. In particular, this model predicts mechanisms by which applied electric fields change the transmembrane potential of the myocardial cells. During unipolar stimulation, the bidomain model can explain "make" and "break" stimulation. Furthermore, it elucidates the cause of the "dip" in the anodal strength-interval curve, and predicts the initiation of novel quatrefoil reentry patterns. These results are beginning to shed light on the mechanisms of arrhythmia induction and defibrillation.

  11. Right Ventricular Versus Biventricular Pacing for Heart Failure and Atrioventricular Block. (United States)

    Beck, Hiroko; Curtis, Anne B


    The use of cardiac resynchronization therapy (CRT) is well accepted as an important option for the treatment of patients with systolic heart failure and prolonged QRS duration. CRT for patients with narrow QRS complexes is reserved for patients who are undergoing implantation of new or replacement pacemakers or implantable cardioverter defibrillators with an anticipated significant requirement for ventricular pacing. The Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) Trial examined the role of CRT in heart failure patients with atrioventricular block and demonstrated significantly better outcomes with CRT compared to right ventricular pacing. On the other hand, conflicting preliminary data were reported by the Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace) Trial investigators. In this review, we will discuss the adverse consequences of chronic right ventricular pacing, the options of alternate pacing sites in the right ventricle versus biventricular pacing, and the findings from the BLOCK HF Trial as well as the preliminary data from the BioPace Trial. Our goal is to explore the role of biventricular pacing in patients with atrioventricular block.

  12. Biventricular pacing with ventricular fusion by intrinsic activation in cardiac resynchronization therapy. (United States)

    Guo, Tao; Li, Ruijie; Zhang, Limei; Luo, Zhiling; Zhao, Ling; Yang, Jun; Pu, Lijin; Hua, Baotong


    We sought to evaluate the impact of biventricular (BiV) pacing with ventricular fusion by intrinsic atrioventricular nodal (AVN) conduction (BiV + intrinsic pacing) on clinical outcomes in patients with chronic heart failure (CHF) receiving cardiac resynchronization therapy (CRT).A total of 44 patients were randomized to receive either BiV or BiV + intrinsic pacing for one month. Echocardiographic optimization was performed for the BiV pacing mode, while the BiV + intrinsic pacing mode was achieved by titrating AV delay under electrocardiography (ECG) monitoring. Symptoms, quality of life, ECG, echocardiography, and cardiovascular events were recorded at baseline and the end of the follow-up for each pacing mode.Patients undergoing BiV + intrinsic pacing mode had shorter QRS duration compared to those with conventional BiV pacing (118.4 ± 21.6 ms versus 146.4 ± 5.3 ms, P Heart Failure Questionnaire (MLHFQ) scores (12.5 ± 6.6 versus 18.2 ± 12.3, P = 0.0001).Treating CHF patients with BiV+intrinsic pacing resulted in improved cardiac function and quality of life. BiV + intrinsic pacing can be used in CHF patients with sinus rhythm and normal AV nodal conduction to improve CRT efficacy.

  13. The Influence of a Pacesetter on Psychological Responses and Pacing Behavior during a 1600 m Run

    Directory of Open Access Journals (Sweden)

    Christopher L. Fullerton, Andrew M. Lane, Tracey J. Devonport


    Full Text Available This study compared the effects of following a pacer versus following a self-paced plan on psychological responses and pacing behavior in well-trained distance runners. Pacing in the present study was individually tailored where each participant developed a personal strategy to ensure their goal time was achieved. We expected that following a pacer would associate with goal achievement, higher pre-run confidence, positive emotions and lower perceived exertion during performance. In a mixed-design repeated-measures study, nineteen well-trained runners completed two 1600m running time trials. Ten runners had a pacer (paced group who supported their individual pacing strategy, and nine participants self-paced running alone (control group. Both groups could check pace using their wrist watch. In contrast to our expectation, results indicated that the paced group reported higher pre-run anxiety with no significant differences in finish time, goal confidence, goal difficulty, perceived exertion, and self-rated performance between groups. We suggest that following a pacer is a skill that requires learning. Following a personalised pacer might associate with higher anxiety due to uncertainty in being able to keep up with the pacer and public visibility of dropping behind, something that is not so observable in a self-paced run completed alone. Future research should investigate mechanisms associated with effective pacing.

  14. The BATSE Gamma-Ray Burst Spectral Catalog. 1; High Time Resolution Spectroscopy of Bright Bursts Using High Energy Resolution Data (United States)

    Preece, Robert D.; Briggs, Michael S.; Mallozzi, Robert S.; Pendleton, Geoffrey N.; Paciesas, W. S.; Band, David L.


    This is the first in a series of gamma-ray burst spectroscopy catalogs from the Burst And Transient Source Experiment (BATSE) on the Compton Gamma Ray Abstract: Observatory, each covering a different aspect of burst phenomenology. In this paper, we present time-sequences of spectral fit parameters for 156 bursts selected either for their high peak flux or fluence.

  15. Ischemic Stroke with Cardiac Pacemaker Implantation: Comparison of Physiological and Ventricular Pacing Modes. (United States)

    Kato, Yuji; Hayashi, Takeshi; Kato, Ritsushi; Tanahashi, Norio; Takao, Masaki


    The clinical characteristics of ischemic stroke in patients with a pacemaker (PM) are not well understood. Forty-six ischemic stroke patients with a PM were investigated retrospectively, and the impact of different pacing modes was compared. The patients were divided into a physiological pacing group (n = 22) and a ventricular pacing group (n = 24). The prevalence of atrial fibrillation (AF) was significantly higher in the ventricular pacing group (36% versus 75%; P = .008). The mean left atrial dimension was relatively large in the ventricular pacing group than in the physiological pacing group (44.5 ± 6.7 mm versus 39.1 ± 8.5 mm, respectively; P = .071). Twenty-four percent of the patients were receiving anticoagulants, whereas 41% of the patients were receiving antiplatelet drugs. Cardioembolism was the most common stroke subtype in both groups. Although there was no statistically significant difference, neurological severity on admission was higher in the ventricular pacing group than in the physiological pacing group (P = .061). Functional outcomes, excluding patients with transient ischemic attack or prior stroke, significantly declined in the ventricular pacing group compared with the physiological pacing group (P = .044). The avoidance of the ventricular pacing mode may result in improved clinical outcomes. In patients without persistent AF, it may be important to select physiological pacing instead of ventricular pacing to decrease potential stroke severity. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  16. Supernova sheds light on gamma-ray bursts

    CERN Multimedia


    On 29 March the HETE-II satellite detected the most violent explosion in the universe to date - an enormous burst of gamma rays. Observers across the world recorded and studied the event. It appears to prove that gamma ray bursts originate in supernovae (1 page)

  17. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.


    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  18. Multiparameter Monitoring and Prevention of Fault-Slip Rock Burst

    Directory of Open Access Journals (Sweden)

    Shan-chao Hu


    Full Text Available Fault-slip rock burst is one type of the tectonic rock burst during mining. A detailed understanding of the precursory information of fault-slip rock burst and implementation of monitoring and early warning systems, as well as pressure relief measures, are essential to safety production in deep mines. This paper first establishes a mechanical model of stick-slip instability in fault-slip rock bursts and then reveals the failure characteristics of the instability. Then, change rule of mining-induced stress and microseismic signals before the occurrence of fault-slip rock burst are proposed, and multiparameter integrated early warning methods including mining-induced stress and energy are established. Finally, pressure relief methods targeting large-diameter boreholes and coal seam infusion are presented in accordance with the occurrence mechanism of fault-slip rock burst. The research results have been successfully applied in working faces 2310 of the Suncun Coal Mine, and the safety of the mine has been enhanced. These research results improve the theory of fault-slip rock burst mechanisms and provide the basis for prediction and forecasting, as well as pressure relief, of fault-slip rock bursts.

  19. Gamma ray bursts observed with WATCH‐EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, Niels; Castro-Tirado, A. J.


    The WATCH wide field x‐ray monitor has the capability of independently locating bright Gamma Ray Bursts to 1° accuracy. We report the preliminary positions of 12 Gamma Ray Bursts observed with the WATCH monitor flown on the ES spacecraft EURECA during its 11 month mission. Also the recurrence...

  20. WATCH observations of gamma ray bursts during 1990–1992

    DEFF Research Database (Denmark)

    Castro-Tirado, A.; Brandt, Søren; Lund, Niels


    The first WATCH/GRANAT Gamma‐Ray Burst Catalogue comprises 70 events which have been detected by WATCH during the period December 1989–September 1992. 32 GRBs could be localized within a 3σ error radii of 1°. We have found a weak (2.2σ) clustering of these 32 bursts towards the Galactic Center...

  1. 49 CFR 179.400-6 - Bursting and buckling pressure. (United States)


    ... 49 Transportation 2 2010-10-01 2010-10-01 false Bursting and buckling pressure. 179.400-6 Section 179.400-6 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS... and 107A) § 179.400-6 Bursting and buckling pressure. (a) [Reserved] (b) The outer jacket of the...

  2. Observations of cosmic gamma ray bursts with WATCH on EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, N.; Castro-Tirado, A. J.


    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy, trap...

  3. Hydrodynamics of burst swimming fish larvae; a conceptual model approach

    NARCIS (Netherlands)

    Verhagen, J.H.G.


    Burst swimming of fish larvae is analysed from a hydrodynamic point of view. A picture of the expected flow pattern is presented based on information in literature on unsteady-flow patterns around obstacles in the intermediate Reynolds number region. It is shown that the acceleration stage of burst

  4. Large tundra methane burst during onset of freezing

    DEFF Research Database (Denmark)

    Mastepanov, Mikhail; Sigsgaard, Charlotte; Dlugokencky, Edward J.


    of global atmospheric methane concentrations indicate that the observed early winter emission burst improves the agreement between the simulated seasonal cycle and atmospheric data from latitudes north of 60N. Our findings suggest that permafrost-associated freeze-in bursts of methane missions from tundra...

  5. Periodic Bursts of Jovian Non-Io Decametric Radio Emission (United States)

    Panchenko, M.; Rucker, H O.; Farrell, W. M.


    During the years 2000-2011 the radio instruments onboard Cassini, Wind and STEREO spacecraft have Recorded a large amount of the Jovian decametric radio emission (DAM). In this paper we report on the analysis of the new type of Jovian periodic radio bursts recently revealed in the decametric frequency range. These bursts, which are non-Io component of DAM, are characterized by a strong periodic reoccurrence over several Jovian days with a period approx. = 1:5% longer than the rotation rate of the planet's magnetosphere (System III). The bursts are typically observed between 4 and 12 MHz and their occurrence probability has been found to be significantly higher in the sector of Jovian Central Meridian Longitude between 300 deg. and 60 deg. (via 360 deg.). The stereoscopic multispacecraft observations have shown that the radio sources of the periodic bursts radiate in a non-axisymmetric hollow cone-like pattern and sub-corotate with Jupiter remaining active during several planet's rotations. The occurrence of the periodic non-Io DAM bursts is strongly correlated with pulses of the solar wind ram pressure at Jupiter. Moreover the periodic bursts exhibit a tendency to occur in groups every approx. 25 days. The polarization measurements have shown that the periodic bursts are right hand polarized radio emission associated with the Northern magnetic hemisphere of Jupiter. We suggest that periodic non-Io DAM bursts may be connected with the interchange instability in Io plasma torus triggered by the solar wind.

  6. The ionization of gamma-ray burst environments (United States)

    Band, D. L.; Hartmann, D. H.


    If a gamma-ray burst (GRB) occurs in a neutral medium, ionizing radiation associated with the burst will flash-photoionize a region surrounding the source. Detection of the line emission from this ionized region can constrain the flux of ionizing radiation accompanying the GRB and the density and ionization state of the environment surrounding the burst source. If the medium is sufficiently dense then the ionized region will recombine and fade on human timescales, aiding in the detection of the burst location and further constraining the density of the medium. However, dust within the dense medium may attenuate the line flux; the burst is unlikely to melt the dust along the line-of-sight. Astronomically interesting flux limits can be established by observations with reasonable integration times on a major telescope (e.g., 3 meter or larger).

  7. Pressure vessel burst test program - Progress paper No. 3 (United States)

    Cain, Maurice R.; Sharp, Douglas E.; Coleman, Michael D.


    An updated progress report is provided on a program developed to study through test and analysis, the characteristics of blast waves and fragmentation generated by ruptured gas filled pressure vessels. Prior papers on this USAF/NASA/General Physics program were presented to the AIAA in July 1990 and June 1991. Ten pressure vessels have been burst using pneumatic pressure. Tests were designed to explore burst characteristics and used an instrumented arena. Data trends for current experiments are presented. This paper is the third progress report on the program and addresses: (1) a brief review of current methods for assessing vessel safety and burst parameters, (2) a review of pneumatic burst testing operations and testing results, including a comparison to current methods for burst assessment, and (3) a review of the basis for the current test program including planned testing.

  8. INTEGRAL monitoring of unusually long X-ray bursts

    DEFF Research Database (Denmark)

    Thermonuclear bursts on the surface of accreting neutron stars in low mass X-ray binaries have been studied for many years and have in a few cases confirmed theoretical models of nuclear ignition and burning mechanisms. The large majority of X-ray bursts last less than 100s. A good number of the ...... bursting regimes and the accretion states of the system, as described by the current burst theory....... of the known X-ray bursters are frequently observed by INTEGRAL, in particular in the frame of the Key Programmes. Taking advantage of the INTEGRAL instrumentation, an international collaboration led by the JEM-X team at the Danish National Space Institute has been monitoring the occurrence of uncommon burst...

  9. Ablation of silicon with bursts of femtosecond laser pulses (United States)

    Gaudiuso, Caterina; Kämmer, Helena; Dreisow, Felix; Ancona, Antonio; Tünnermann, Andreas; Nolte, Stefan


    We report on an experimental investigation of ultrafast laser ablation of silicon with bursts of pulses. The pristine 1030nm-wavelength 200-fs pulses were split into bursts of up to 16 sub-pulses with time separation ranging from 0.5ps to 4080ps. The total ablation threshold fluence was measured depending on the burst features, finding that it strongly increases with the number of sub-pulses for longer sub-pulse delays, while a slowly increasing trend is observed for shorter separation time. The ablation depth per burst follows two different trends according to the time separation between the sub-pulses, as well as the total threshold fluence. For delays shorter than 4ps it decreases with the number of pulses, while for time separations longer than 510ps, deeper craters were achieved by increasing the number of subpulses in the burst, probably due to a change of the effective penetration depth.

  10. A bright millisecond radio burst of extragalactic origin. (United States)

    Lorimer, D R; Bailes, M; McLaughlin, M A; Narkevic, D J; Crawford, F


    Pulsar surveys offer a rare opportunity to monitor the radio sky for impulsive burst-like events with millisecond durations. We analyzed archival survey data and found a 30-jansky dispersed burst, less than 5 milliseconds in duration, located 3 degrees from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the universe imply that the burst is less than 1 gigaparsec distant. No further bursts were seen in 90 hours of additional observations, which implies that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and, if detected, could serve as cosmological probes.

  11. Cosmology and the Subgroups of Gamma-ray Bursts

    Directory of Open Access Journals (Sweden)

    A. Mészáros


    Full Text Available Both short and intermediate gamma-ray bursts are distributed anisotropically in the sky (Mészáros, A. et al. ApJ, 539, 98 (2000, Vavrek, R. et al. MNRAS, 391, 1 741 (2008. Hence, in the redshift range, where these bursts take place, the cosmological principle is in doubt. It has already been noted that short bursts should be mainly at redshifts smaller than one (Mészáros, A. et al. Gamma-ray burst: Sixth Huntsville Symp., AIP, Vol. 1 133, 483 (2009; Mészáros, A. et al. Baltic Astron., 18, 293 (2009. Here we show that intermediate bursts should be at redshifts up to three.

  12. The supernova-gamma-ray burst-jet connection. (United States)

    Hjorth, Jens


    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bipolar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star, whereas the (56)Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper, I summarize the observational status of the supernova-gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A--with its luminous supernova but intermediate high-energy luminosity--as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insights into supernova explosions in general.

  13. Analyses of resource reservation schemes for optical burst switching networks (United States)

    Solanska, Michaela; Scholtz, Lubomir; Ladanyi, Libor; Mullerova, Jarmila


    With growing demands of Internet Protocol services for transmission capacity and speed, the Optical Burst Switching presents the solution for future high-speed optical networks. Optical Burst Switching is a technology for transmitting large amounts of data bursts through a transparent optical switching network. To successfully transmit bursts over OBS network and reach the destination node, resource reservation schemes have to be implemented to allocate resources and configure optical switches for that burst at each node. The one-way resource reservation schemes and the performance evaluation of reservation schemes are presented. The OBS network model is performed using OMNeT++ simulation environment. During the reservation of network resources, the optical cross-connect based on semiconductor optical amplifier is used as the core node. Optical switches based on semiconductor optical amplifiers are a promising technology for high-speed optical communication networks.

  14. Gamma-Ray Burst Prompt Correlations

    Directory of Open Access Journals (Sweden)

    M. G. Dainotti


    Full Text Available The mechanism responsible for the prompt emission of gamma-ray bursts (GRBs is still a debated issue. The prompt phase-related GRB correlations can allow discriminating among the most plausible theoretical models explaining this emission. We present an overview of the observational two-parameter correlations, their physical interpretations, and their use as redshift estimators and possibly as cosmological tools. The nowadays challenge is to make GRBs, the farthest stellar-scaled objects observed (up to redshift z=9.4, standard candles through well established and robust correlations. However, GRBs spanning several orders of magnitude in their energetics are far from being standard candles. We describe the advances in the prompt correlation research in the past decades, with particular focus paid to the discoveries in the last 20 years.

  15. Bursting of filaments in the plasma focus

    International Nuclear Information System (INIS)

    Gratton, F.T.L.


    Photographs of the current sheath of (low energy) plasma focus show a disruption of the filaments. This phenomenon is interpreted as a vortex breakdown. Physical parameters which support this hypothesis are obtained from measurements, from the theoretical thickness of the current sheath given by Nardi and from some models of the plasma flow. The widening of a vortex due to axial velocity increase is analyzed by means of magnetohydrodynamic collinear models. The main results are: (1) the existence of a limit separating supercritical from subcritical regimes (their character changes with the ratio between kinetic and magnetic energy); (2) the existence of flow regimes where the vortex radius remains approximately constant for moderate increments of the external velocity; (3) the structure of the vortex may change substantially for a sufficiently large increment of the external velocity, even in subcritical states; (4) the possibility that a burst of the vortex may occur when the external velocity suffers a slowdown

  16. Pilot trial of an age-paced parenting newsletter. (United States)

    Keane, Brigid; Waterston, Tony; McConachie, Helen; Towner, Elizabeth; Cook, Margaret; Birks, Eileen


    Supporting parents in the first three years of a child's life has the potential to produce successful outcomes. Present government initiatives such as Sure Start focus on this age group. An American educational intervention, in the style of a monthly newsletter, was adapted for use in the UK for parents of young children. Topics were presented in an easy-to-read format and focused on infant emotional development, parent interaction and play. Newsletters, called Baby Express were posted at monthly intervals to the family home providing age-paced information which could meet the specific needs of parents at that stage of their child's life. The aim of the study was to determine the applicability of the newsletter to UK parents and evaluate their satisfaction. Sixty home-based interviews were conducted and 95 per cent of mothers reported reading all or part of the newsletter. Changes in parenting style were spontaneously reported by 28 per cent of mothers. This study found that an aged-paced parenting newsletter was an acceptable and useful method of supporting parents in the early months of a child's life and promotes positive changes in parenting behaviour.

  17. Social Interaction in Self-paced Distance Education

    Directory of Open Access Journals (Sweden)

    Terry Anderson


    Full Text Available In this paper we present a case study of a self-paced university course that was originally designed to support independent, self-paced study at distance. We developed a social media intervention, in design-based research terms, that allows these independent students to contribute archived content to enhance the course, to engage in discussions with other students and to share as little or as much personal information with each other as they wished. We describe the learning design for the intervention and present survey data of student and tutor perception of value and content analysis of the archived contributions. The results indicate that the intervention was positively received by tutors and by the majority (but not all students and that the archive created by the students’ contributions was adding value to the course. We conclude that the intervention was a modest, yet manageable example of a learning enhancement to a traditional cognitive-behavioral, course that has positive impact and potential with little negative impact on workload.

  18. The influence of collective behaviour on pacing in endurance competitions

    Directory of Open Access Journals (Sweden)

    Andrew eRenfree


    Full Text Available A number of theoretical models have been proposed to explain pacing strategies in individual competitive endurance events. These have typically related to internal regulatory processes informing the making of decisions relating to muscular work rate. Despite a substantial body of research investigating the influence of collective group dynamics on individual behaviours in various animal species, this issue has not been comprehensively studied in individual athletic events. This is surprising given that athletes directly compete in close proximity to one another, and that collective behaviour has also been observed in other human environments. Whilst reasons for adopting collective behaviour are not fully understood, it is thought to result from individual agents following simple local rules resulting in seemingly complex large systems acting to confer some biological advantage to the collective as a whole. Although such collective behaviours may generally be beneficial, endurance events are complicated by the fact that increasing levels of physiological disruption as activity progresses may compromise the ability of individuals to continue to interact with other group members. This could result in early fatigue and relative underperformance due to suboptimal utilisation of physiological resources by some athletes. Alternatively, engagement with a collective behaviour may benefit all due to a reduction in the complexity of decisions to be made and a subsequent reduction in cognitive loading and mental fatigue. This paper seeks evidence for collective behaviour in previously published analyses of pacing behaviour and proposes mechanisms through which it could potentially be either beneficial, or detrimental to individual performance.

  19. Data reproducibility of pace strategy in a laboratory test run. (United States)

    de França, Elias; Xavier, Ana Paula; Hirota, Vinicius Barroso; Côrrea, Sônia Cavalcanti; Caperuto, Érico Chagas


    This data paper contains data related to a reproducibility test for running pacing strategy in an intermittent running test until exhaustion. Ten participants underwent a crossover study (test and retest) with an intermittent running test. The test was composed of three-minute sets (at 1 km/h above Onset Blood Lactate Accumulation) until volitional exhaustion. To assess pace strategy change, in the first test participants chose the rest time interval (RTI) between sets (ranging from 30 to 60 s) and in the second test the maximum RTI values were either the RTI chosen in the first test (maximum RTI value), or less if desired. To verify the reproducibility of the test, rating perceived exertion (RPE), heart rate (HR) and blood plasma lactate concentration ([La]p) were collected at rest, immediately after each set and at the end of the tests. As results, RTI, RPE, HR, [La]p and time to exhaustion were not statistically different (p>0.05) between test and retest, as well as they demonstrated good intraclass correlation.

  20. Data reproducibility of pace strategy in a laboratory test run

    Directory of Open Access Journals (Sweden)

    Elias de França


    Full Text Available This data paper contains data related to a reproducibility test for running pacing strategy in an intermittent running test until exhaustion. Ten participants underwent a crossover study (test and retest with an intermittent running test. The test was composed of three-minute sets (at 1 km/h above Onset Blood Lactate Accumulation until volitional exhaustion. To assess pace strategy change, in the first test participants chose the rest time interval (RTI between sets (ranging from 30 to 60 s and in the second test the maximum RTI values were either the RTI chosen in the first test (maximum RTI value, or less if desired. To verify the reproducibility of the test, rating perceived exertion (RPE, heart rate (HR and blood plasma lactate concentration ([La]p were collected at rest, immediately after each set and at the end of the tests. As results, RTI, RPE, HR, [La]p and time to exhaustion were not statistically different (p>0.05 between test and retest, as well as they demonstrated good intraclass correlation.


    International Nuclear Information System (INIS)

    Hirota, Tomoya; Honma, Mareki; Kim, Mi Kyoung; Kobayashi, Hideyuki; Shibata, Katsunori M.; Tsuboi, Masato; Fujisawa, Kenta; Kawaguchi, Noriyuki; Imai, Hiroshi; Omodaka, Toshihiro; Shimoikura, Tomomi; Yonekura, Yoshinori


    In 2011 February, a burst event of the H 2 O maser in Orion KL (Kleinmann-Low object) has started after a 13 year silence. This is the third time such phenomena has been detected in Orion KL, followed by the events in 1979-1985 and 1998. We have carried out astrometric observations of the bursting H 2 O maser features in Orion KL with the VLBI Exploration of Radio Astrometry (VERA), a Japanese very long baseline interferometry network dedicated for astrometry. The total flux of the bursting feature at the local standard of rest (LSR) velocity of 7.58 km s -1 reaches 4.4 x 10 4 Jy in 2011 March. The intensity of the bursting feature is three orders of magnitude larger than that of the same velocity feature in the quiescent phase in 2006. Two months later, another new feature appears at the LSR velocity of 6.95 km s -1 in 2011 May, separated by 12 mas north of the 7.58 km s -1 feature. Thus, the current burst occurs at two spatially different features. The bursting masers are elongated along the northwest-southeast direction as reported in the previous burst in 1998. We determine the absolute positions of the bursting features for the first time ever with a submilliarcsecond (mas) accuracy. Their positions are coincident with the shocked molecular gas called the Orion Compact Ridge. We tentatively detect the absolute proper motions of the bursting features toward the southwest direction. It is most likely that the outflow from the radio source I or another young stellar object interacting with the Compact Ridge is a possible origin of the H 2 O maser burst.

  2. Does Twitter trigger bursts in signature collections? (United States)

    Yamaguchi, Rui; Imoto, Seiya; Kami, Masahiro; Watanabe, Kenji; Miyano, Satoru; Yuji, Koichiro


    The quantification of social media impacts on societal and political events is a difficult undertaking. The Japanese Society of Oriental Medicine started a signature-collecting campaign to oppose a medical policy of the Government Revitalization Unit to exclude a traditional Japanese medicine, "Kampo," from the public insurance system. The signature count showed a series of aberrant bursts from November 26 to 29, 2009. In the same interval, the number of messages on Twitter including the keywords "Signature" and "Kampo," increased abruptly. Moreover, the number of messages on an Internet forum that discussed the policy and called for signatures showed a train of spikes. In order to estimate the contributions of social media, we developed a statistical model with state-space modeling framework that distinguishes the contributions of multiple social media in time-series of collected public opinions. We applied the model to the time-series of signature counts of the campaign and quantified contributions of two social media, i.e., Twitter and an Internet forum, by the estimation. We found that a considerable portion (78%) of the signatures was affected from either of the social media throughout the campaign and the Twitter effect (26%) was smaller than the Forum effect (52%) in total, although Twitter probably triggered the initial two bursts of signatures. Comparisons of the estimated profiles of the both effects suggested distinctions between the social media in terms of sustainable impact of messages or tweets. Twitter shows messages on various topics on a time-line; newer messages push out older ones. Twitter may diminish the impact of messages that are tweeted intermittently. The quantification of social media impacts is beneficial to better understand people's tendency and may promote developing strategies to engage public opinions effectively. Our proposed method is a promising tool to explore information hidden in social phenomena.

  3. Does Twitter trigger bursts in signature collections?

    Directory of Open Access Journals (Sweden)

    Rui Yamaguchi

    Full Text Available INTRODUCTION: The quantification of social media impacts on societal and political events is a difficult undertaking. The Japanese Society of Oriental Medicine started a signature-collecting campaign to oppose a medical policy of the Government Revitalization Unit to exclude a traditional Japanese medicine, "Kampo," from the public insurance system. The signature count showed a series of aberrant bursts from November 26 to 29, 2009. In the same interval, the number of messages on Twitter including the keywords "Signature" and "Kampo," increased abruptly. Moreover, the number of messages on an Internet forum that discussed the policy and called for signatures showed a train of spikes. METHODS AND FINDINGS: In order to estimate the contributions of social media, we developed a statistical model with state-space modeling framework that distinguishes the contributions of multiple social media in time-series of collected public opinions. We applied the model to the time-series of signature counts of the campaign and quantified contributions of two social media, i.e., Twitter and an Internet forum, by the estimation. We found that a considerable portion (78% of the signatures was affected from either of the social media throughout the campaign and the Twitter effect (26% was smaller than the Forum effect (52% in total, although Twitter probably triggered the initial two bursts of signatures. Comparisons of the estimated profiles of the both effects suggested distinctions between the social media in terms of sustainable impact of messages or tweets. Twitter shows messages on various topics on a time-line; newer messages push out older ones. Twitter may diminish the impact of messages that are tweeted intermittently. CONCLUSIONS: The quantification of social media impacts is beneficial to better understand people's tendency and may promote developing strategies to engage public opinions effectively. Our proposed method is a promising tool to explore

  4. Post-Launch Analysis of Swift's Gamma-Ray Burst Detection Sensitivity (United States)

    Band, David L.


    The dependence of Swift#s detection sensitivity on a burst#s temporal and spectral properties shapes the detected burst population. Using s implified models of the detector hardware and the burst trigger syste m I find that Swift is more sensitive to long, soft bursts than CGRO# s BATSE, a reference mission because of its large burst database. Thu s Swift has increased sensitivity in the parameter space region into which time dilation and spectral redshifting shift high redshift burs ts.

  5. The LOFT Burst Alert System and its Burst On-board Trigger

    DEFF Research Database (Denmark)

    Schanne, Stephane; Götz, Diego; Provost, Herve Le


    for a world-wide observers community. However, observing the quickly decaying GRB afterglows with ground-based telescopes needs the rapid knowledge of their precise localization. The task of the Loft Burst Alert System (LBAS) is therefore to detect in near- real-time GRBs (about 120 detections expected per...... system). In this article we present the LBAS and its components, the LBOT and the associated ground-segment....

  6. Monitoring burst (M-burst) — A novel framework of failure localization in all-optical mesh networks

    KAUST Repository

    Ali, Mohammed L.


    Achieving instantaneous and precise failure localization in all-optical wavelength division multiplexing (WDM) networks has been an attractive feature of network fault management systems, and is particularly important when failure-dependent protection is employed. The paper introduces a novel framework of real-time failure localization in all-optical WDM mesh networks, called monitoring-burst (m-burst), which aims to initiate a graceful compromise between consumed monitoring resources and monitoring delay. Different from any previously reported solution, the proposed m-burst framework has a single monitoring node (MN) which launches optical bursts along a set of pre-defined close-loop routes, called monitoring cycles (m-cycles), to probe the links along the m-cycles. Bursts along different m-cycles are kept non-overlapping through any link of the network. By identifying the lost bursts due to single link failure events only, the MN can unambiguously localize the failed link in at least 3-connected networks. We will justify the feasibility and applicability of the proposed m-burst framework in the scenario of interest. To avoid possible collision among optical bursts launched by the MN, we define the problem of collision-free scheduling and formulate it into an integer linear program (ILP) in order to minimize the monitoring delay. Numerical results demonstrate the effectiveness of the proposed framework and the proposed solution.

  7. Pacing a data transfer operation between compute nodes on a parallel computer (United States)

    Blocksome, Michael A [Rochester, MN


    Methods, systems, and products are disclosed for pacing a data transfer between compute nodes on a parallel computer that include: transferring, by an origin compute node, a chunk of an application message to a target compute node; sending, by the origin compute node, a pacing request to a target direct memory access (`DMA`) engine on the target compute node using a remote get DMA operation; determining, by the origin compute node, whether a pacing response to the pacing request has been received from the target DMA engine; and transferring, by the origin compute node, a next chunk of the application message if the pacing response to the pacing request has been received from the target DMA engine.

  8. Turbulence control with local pacing and its implication in cardiac defibrillation (United States)

    Cao, Zhoujian; Li, Pengfei; Zhang, Hong; Xie, Fagen; Hu, Gang


    In this review article, we describe turbulence control in excitable systems by using a local periodic pacing method. The controllability conditions of turbulence suppression and the mechanisms underlying these conditions are analyzed. The local pacing method is applied to control Winfree turbulence (WT) and defect turbulence (DT) induced by spiral-wave breakup. It is shown that WT can always be suppressed by local pacing if the pacing amplitude and frequency are properly chosen. On the other hand, the pacing method can achieve suppression of DT induced by instabilities associated with the motions of spiral tips while failing to suppress DT induced by the instabilities of wave propagation far from tips. In the latter case, an auxiliary method of applying gradient field is suggested to improve the control effects. The implication of this local pacing method to realistic cardiac defibrillation is addressed.

  9. Closest Gamma Ray Burst Providing Scientists With Crucial Test for Burst Physics (United States)


    The closest Gamma Ray Burst (GRB) yet known is providing astronomers with a rare opportunity to gain information vital to understanding these powerful cosmic explosions. Extremely precise radio-telescope observations already have ruled out one proposed mechanism for the bursts. "This is the closest and brightest GRB we've ever seen, and we can use it to decipher the physics of how these bursts work," said Greg Taylor of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Taylor worked with Dale Frail, also of the NRAO, along with Prof. Shri Kulkarni and graduate student Edo Berger of Caltech in studying a GRB detected on March 29, 2003. The scientists presented their findings to the American Astronomical Society's meeting in Nashville, TN. VLBA image of GRB 030329 VLBA IMAGE of GRB 030329 CREDIT: NRAO/AUI/NSF (Click on Image for Larger Version) Taylor and Frail used the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) and other radio telescopes to study the burst, known as GRB 030329. In a series of observations from April 1 to May 19, they determined the size of the expanding "fireball" from the burst and measured its position in the sky with great precision. At a distance of about 2.6 billion light-years, GRB 030329 is hardly next door. However, compared to other GRBs at typical distances of 8-10 billion light-years, it presents an easier target for study. "We only expect to see one burst per decade this close," said Frail. The precise measurement of the object's position allowed the scientists to show that one theoretical model for GRBs can be ruled out. This model, proposed in 2000, says that the radio-wave energy emitted by the GRB comes from "cannonballs" of material shot from the explosion at extremely high speeds. "The 'cannonball model' predicted that we should see the radio-emitting object move across the sky by a specific amount. We have not seen that motion," Taylor said. The currently standard "fireball model" of GRBs

  10. Comparison of pacing algorithms to avoid unnecessary ventricular pacing in patients with sick sinus node syndrome: a single-centre, observational, parallel study. (United States)

    Poghosyan, Hermine R; Jamalyan, Smbat V


    Reduction of unnecessary ventricular pacing (uVP) is an essential component in the treatment strategy in any pacing population in general. The aim of this study was to evaluate the efficacy of different algorithms to reduce uVP in an adult population with sick sinus syndrome (SSS) treated outside of clinical trials. Evaluation of the relationship between different types of pacing algorithms and clinical outcomes is also provided. This was a single-centre, observational, parallel study, based on retrospective analysis of the Arrhythmology Cardiology Center of Armenia electronic clinical database. This study evaluated atrial pacing percentage (AP%), ventricular pacing percentage (VP%), and the incidence of atrial high rate episodes in 56 patients with SSS using three different pacing strategies: managed VP, search atrioventricular (AV), and fixed long AV. We did not find statistically significant differences in the amount of VP between the groups. Although the atrial high rate percentage (AHR%) tended to be higher in the fixed long AV group, this difference was not statistically significant. Mean VP% and AP% were similar in all three groups. In our study, all three programmed strategies produced the same mean AP% and VP%, and were equally efficient in uVP reduction. There was no relationship between chosen algorithms and the incidence of pacemaker syndrome, hospitalizations, or change in New York Heart Association class. The percentage of AHR was not associated with pacing strategy or co-morbidities but showed borderline correlation with left atrial size.

  11. The pacing stress test: thallium-201 myocardial imaging after atrial pacing. Diagnostic value in detecting coronary artery disease compared with exercise testing

    International Nuclear Information System (INIS)

    Heller, G.V.; Aroesty, J.M.; Parker, J.A.; McKay, R.G.; Silverman, K.J.; Als, A.V.; Come, P.C.; Kolodny, G.M.; Grossman, W.


    Many patients suspected of having coronary artery disease are unable to undergo adequate exercise testing. An alternate stress, pacing tachycardia, has been shown to produce electrocardiographic changes that are as sensitive and specific as those observed during exercise testing. To compare thallium-201 imaging after atrial pacing stress with thallium imaging after exercise stress, 22 patients undergoing cardiac catheterization were studied with both standard exercise thallium imaging and pacing thallium imaging. Positive ischemic electrocardiographic changes (greater than 1 mm ST segment depression) were noted in 11 of 16 patients with coronary artery disease during exercise, and in 15 of the 16 patients during atrial pacing. One of six patients with normal or trivial coronary artery disease had a positive electrocardiogram with each test. Exercise thallium imaging was positive in 13 of 16 patients with coronary artery disease compared with 15 of 16 patients during atrial pacing. Three of six patients without coronary artery disease had a positive scan with exercise testing, and two of these same patients developed a positive scan with atrial pacing. Of those patients with coronary artery disease and an abnormal scan, 85% showed redistribution with exercise testing compared with 87% during atrial pacing. Segment by segment comparison of thallium imaging after either atrial pacing or exercise showed that there was a good correlation of the location and severity of the thallium defects (r . 0.83, p . 0.0001, Spearman rank correlation). It is concluded that the location and presence of both fixed and transient thallium defects after atrial pacing are closely correlated with the findings after exercise testing

  12. Elevational trends in life histories: revising the pace-of-life framework. (United States)

    Hille, Sabine M; Cooper, Caren B


    Life-history traits in birds, such as lifespan, age at maturity, and rate of reproduction, vary across environments and in combinations imposed by trade-offs and limitations of physiological mechanisms. A plethora of studies have described the diversity of traits and hypothesized selection pressures shaping components of the survival-reproduction trade-off. Life-history variation appears to fall along a slow-fast continuum, with slow pace characterized by higher investment in survival over reproduction and fast pace characterized by higher investment in reproduction over survival. The Pace-of-Life Syndrome (POLS) is a framework to describe the slow-fast axis of variation in life-history traits and physiological traits. The POLS corresponds to latitudinal gradients, with tropical birds exhibiting a slow pace of life. We examined four possible ways that the traits of high-elevation birds might correspond to the POLS continuum: (i) rapid pace, (ii) tropical slow pace, (iii) novel elevational pace, or (iv) constrained pace. Recent studies reveal that birds breeding at high elevations in temperate zones exhibit a combination of traits creating a unique elevational pace of life with a central trade-off similar to a slow pace but physiological trade-offs more similar to a fast pace. A paucity of studies prevents consideration of the possibility of a constrained pace of life. We propose extending the POLS framework to include trait variation of elevational clines to help to investigate complexity in global geographic patterns. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  13. Coronary grafts flow and cardiac pacing modalities: how to improve perioperative myocardial perfusion.

    LENUS (Irish Health Repository)

    D'Ancona, Giuseppe


    OBJECTIVE: Aim of this study was to investigate modifications of coronary grafts flow during different pacing modalities after CABG. MATERIALS AND METHODS: Two separate prospective studies were conducted in patients undergoing CABG and requiring intraoperative epicardial pacing. In a first study (22 patients) coronary grafts flows were measured during dual chamber pacing (DDD) and during ventricular pacing (VVI). In a second study (10 patients) flows were measured during DDD pacing at different atrio-ventricular (A-V) delay periods. A-V delay was adjusted in 25 ms increments from 25 to 250 ms and flow measurements were performed for each A-V delay increment. A transit time flowmeter was used for the measurements. RESULTS: An average of 3.4 grafts\\/patient were performed. In the first study, average coronary graft flow was 47.4+\\/-20.8 ml\\/min during DDD pacing and 41.8+\\/-18.2 ml\\/min during VVI pacing (P = 0.0004). Furthermore average systolic pressure was 94.3+\\/-10.1 mmHg during DDD pacing and 89.6+\\/-12.2 mmHg during VVV pacing (P = 0.0007). No significant differences in diastolic pressure were recorded during the two different pacing modalities. In the second study, maximal flows were achieved during DDD pacing with an A-V delay of 175 ms (54+\\/-9.6 ml\\/min) and minimal flows were detected at 25 ms A-V delay (38.1+\\/-4.7 ml\\/min) (P=ns). No significant differences in systolic or diastolic blood pressure were noticed during the different A-V delays. CONCLUSION: Grafts flowmetry provides an extra tool to direct supportive measures such as cardiac pacing after CABG. DDD mode with A-V delay around 175 ms. should be preferred to allow for maximal myocardial perfusion via the grafts.

  14. Meta-Analysis of Single-Case Research Design Studies on Instructional Pacing. (United States)

    Tincani, Matt; De Mers, Marilyn


    More than four decades of research on instructional pacing has yielded varying and, in some cases, conflicting findings. The purpose of this meta-analysis was to synthesize single-case research design (SCRD) studies on instructional pacing to determine the relative benefits of brisker or slower pacing. Participants were children and youth with and without disabilities in educational settings, excluding higher education. Tau-U, a non-parametric statistic for analyzing data in SCRD studies, was used to determine effect size estimates. The article extraction yielded 13 instructional pacing studies meeting contemporary standards for high quality SCRD research. Eleven of the 13 studies reported small to large magnitude effects when two or more pacing parameters were compared, suggesting that instructional pacing is a robust instructional variable. Brisker instructional pacing with brief inter-trial interval (ITI) produced small increases in correct responding and medium to large reductions in challenging behavior compared with extended ITI. Slower instructional pacing with extended wait-time produced small increases in correct responding, but also produced small increases in challenging behavior compared with brief wait-time. Neither brief ITI nor extended wait-time meets recently established thresholds for evidence-based practice, highlighting the need for further instructional pacing research. © The Author(s) 2016.

  15. Pacing and Self-regulation: Important Skills for Talent Development in Endurance Sports. (United States)

    Elferink-Gemser, Marije T; Hettinga, Florentina J


    Pacing has been characterized as a multifaceted goal-directed process of decision making in which athletes need to decide how and when to invest their energy during the race, a process essential for optimal performance. Both physiological and psychological characteristics associated with adequate pacing and performance are known to develop with age. Consequently, the multifaceted skill of pacing might be under construction throughout adolescence, as well. Therefore, the authors propose that the complex skill of pacing is a potential important performance characteristic for talented youth athletes that needs to be developed throughout adolescence. To explore whether pacing is a marker for talent and how talented athletes develop this skill in middle-distance and endurance sports, they aim to bring together literature on pacing and literature on talent development and self-regulation of learning. Subsequently, by applying the cyclical process of self-regulation to pacing, they propose a practical model for the development of performance in endurance sports in youth athletes. Not only is self-regulation essential throughout the process of reaching the long-term goal of athletic excellence, but it also seems crucial for the development of pacing skills within a race and the development of a refined performance template based on previous experiences. Coaches and trainers are advised to incorporate pacing as a performance characteristic in their talent-development programs by stimulating their athletes to reflect, plan, monitor, and evaluate their races on a regular basis to build performance templates and, as such, improve their performance.

  16. Ventricular Pacing via the Coronary Sinus in a Patient with a Mechanical Tricuspid Valve Prosthesis

    Directory of Open Access Journals (Sweden)

    Janice Swampillai, MD


    Full Text Available Implantation of a transvenous endocardial pacing lead in the right ventricle is contra-indicated after mechanical tricuspid valve replacement; therefore a surgical approach to the epicardium is usually required. This case report describes ventricular pacing via a branch of the coronary sinus in a patient with mechanical mitral, aortic and tricuspid valve replacements. In conclusion, this approach is minimally invasive, provides effective ventricular stimulation with low pacing threshold and stable lead position, and is a feasible option when transvenous right ventricular pacing is not possible.


    Directory of Open Access Journals (Sweden)



    Full Text Available The pace in swimming is very important because it allows swimmers to allocate their forces accordingly, and therefore a distance to travel as quickly as possible. The training pace at different swimmingspeeds and combinations thereof, is an important part of training before the competitions.The definition and maintenance of the stable and swimmer specific speed is difficult to achieve and requires considerable effort and experience. To determine the desired rate of accuracy by the researchers and their coaches used till now, various audio and visual media.However, some of these institutions did not very accurately measure the rate and not all styles of swimming, while other aspects affect the proper swimming. In this construction, a key objective is to solve the problems occurring in the previous constructions, the modern technological development of them and the adaption of the specificities of different swimming styles.This device consists of an electro 3 / 8 of the horse, a flange, a single inverter from 3 / 8 to ½ of the horse, pulleys with taper Bush, flange axle, pulleys, platforms and a 52 meters cable. The assembly and operation is as follows: At the edge of the pool next to the platform is placed the base of pulleys, the electro setis connected to the inverter and the axle flange.Precisely opposite is positioned the other base. Along the pool «moves» the cable that connects the two bases, located 150 cm above the water. A fixed point on the cable is marked with paint in order to be visible to the swimmer during backstroke swimming while for other styles we adapt a lamination at the cable vertically inthe pool, above the surface a sheet of 15 cm which is painted with strong color that is visible from the athlete and will precede him. Setting the speed with inverter it starts from one end of the tank leading to the other, doing a circular motion.The swimmer is required to follow the marked point of the cable in the backstroke or

  18. Understanding the Generation of Network Bursts by Adaptive Oscillatory Neurons

    Directory of Open Access Journals (Sweden)

    Tanguy Fardet


    Full Text Available Experimental and numerical studies have revealed that isolated populations of oscillatory neurons can spontaneously synchronize and generate periodic bursts involving the whole network. Such a behavior has notably been observed for cultured neurons in rodent's cortex or hippocampus. We show here that a sufficient condition for this network bursting is the presence of an excitatory population of oscillatory neurons which displays spike-driven adaptation. We provide an analytic model to analyze network bursts generated by coupled adaptive exponential integrate-and-fire neurons. We show that, for strong synaptic coupling, intrinsically tonic spiking neurons evolve to reach a synchronized intermittent bursting state. The presence of inhibitory neurons or plastic synapses can then modulate this dynamics in many ways but is not necessary for its appearance. Thanks to a simple self-consistent equation, our model gives an intuitive and semi-quantitative tool to understand the bursting behavior. Furthermore, it suggests that after-hyperpolarization currents are sufficient to explain bursting termination. Through a thorough mapping between the theoretical parameters and ion-channel properties, we discuss the biological mechanisms that could be involved and the relevance of the explored parameter-space. Such an insight enables us to propose experimentally-testable predictions regarding how blocking fast, medium or slow after-hyperpolarization channels would affect the firing rate and burst duration, as well as the interburst interval.

  19. Gamma Ray Bursts and the Birth of Black Holes (United States)

    Gehrels, Neil


    Black holes have been predicted since the 1940's from solutions of Einstein's general relativity field equation. There is strong evidence of their existence from astronomical observations, but their origin has remained an open question of great interest. Gamma-ray bursts may the clue. They are powerful explosions, visible to high redshift, and appear to be the birth cries of black holes. The Swift and Fermi missions are two powerful NASA observatories currently in orbit that are discovering how gamma-ray bursts work. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are tremendously luminous and are providing a new tool to study the high redshift universe. One Swift burst at z=8.3 is the most distant object known in the universe. The talk will present the latest gamma-ray burst results from Swift and Fermi and will highlight what they are teaching us about black holes and jet outflows.

  20. Postillumination burst of carbon dioxide in crassalacean Acid metabolism plants. (United States)

    Crews, C E; Vines, H M; Black, C C


    Immediately following exposure to light, a postillumination burst of CO(2) has been detected in Crassulacean acid metabolism plants. A detailed study with pineapple (Ananas comosus) leaves indicates that the postillumination burst changes its amplitude and kinetics during the course of a day. In air, the postillumination burst in pineapple leaves generally is exhibited as two peaks. The postillumination burst is sensitive to atmospheric CO(2) and O(2) concentrations as well as to the light intensity under which plants are grown. We propose that the CO(2) released in the first postillumination burst peak is indicative of photorespiration since it is sensitive to either O(2) or CO(2) concentration while the second CO(2) evolution peak is likely due to decarboxylation of organic acids involved in Crassulacean acid metabolism.In marked contrast to other higher plants, the postillumination burst in Crassulacean acid metabolism plants can be equal to or greater than the rate of photosynthesis. Photosynthesis in pineapple leaves also varies throughout a day. Both photosynthesis and the postillumination burst have a daily variation which apparently is a complex function of degree of leaf acidity, growth light intensity, ambient gas phase, and the time a plant has been exposed to a given gas.

  1. Accelerating Science with the NERSC Burst Buffer Early User Program

    Energy Technology Data Exchange (ETDEWEB)

    Bhimji, Wahid [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bard, Debbie [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Romanus, Melissa [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutgers Univ., New Brunswick, NJ (United States); Paul, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ovsyannikov, Andrey [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Friesen, Brian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bryson, Matt [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Correa, Joaquin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lockwood, Glenn K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Tsulaia, Vakho [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Byna, Suren [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Farrell, Steve [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gursoy, Doga [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Daley, Chris [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beckner, Vince [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Van Straalen, Brian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Tull, Craig [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Weber, Gunther H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wright, Nicholas J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Antypas, Katie [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prabhat, none [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)


    NVRAM-based Burst Buffers are an important part of the emerging HPC storage landscape. The National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory recently installed one of the first Burst Buffer systems as part of its new Cori supercomputer, collaborating with Cray on the development of the DataWarp software. NERSC has a diverse user base comprised of over 6500 users in 700 different projects spanning a wide variety of scientific computing applications. The use-cases of the Burst Buffer at NERSC are therefore also considerable and diverse. We describe here performance measurements and lessons learned from the Burst Buffer Early User Program at NERSC, which selected a number of research projects to gain early access to the Burst Buffer and exercise its capability to enable new scientific advancements. To the best of our knowledge this is the first time a Burst Buffer has been stressed at scale by diverse, real user workloads and therefore these lessons will be of considerable benefit to shaping the developing use of Burst Buffers at HPC centers.

  2. Observations of energitic radiation bursts from thunder activities (United States)

    Tsuchiya, H.; Enoto, T.; Torii, T.; Yuasa, T.; Yamada, S.; Kitacuhi, T.; Nakazawa, K.; Kato, H.; Okano, M.; Makishima, K.


    Energetic radiation bursts have been observed during strong thunderstorms by ground-based detectors as well as high-mountain ones. Those radiation bursts are thought to result from runaway electrons originating from electrons accelerated by strong electric field in lightning discharges and thunderclouds, and hence provide a valuable key to understand particle acceleration in thunder activity. Interestingly, they can be categorized into two bursts by their duration. One consists of short bursts lasting for milli-seconds or less. The other comprises long bursts having duration of a few seconds. In order to better understand both short and long bursts, we have conducted experiments at coastal area of the Japan Sea and a 2770-m altitude observatory. In this talk, we will report on those experiments, showing the two experiments has successfully observed both short and long bursts. Especially, we will focus on high-energy radiations extending over MeV energies, and then discuss a plausible model to explain how those high-energy radiations are produced in thunder activity.

  3. Long X-ray burst monitoring with INTEGRAL

    DEFF Research Database (Denmark)

    X-ray bursts are thermonuclear explosions on the surface of accreting neutron stars in low mass X-ray binary systems. In the frame of the INTEGRAL observational Key Programme over the Galactic Center a good number of the known X-ray bursters are frequently being monitored. An international...... and from our previous proposal for the observation period 2006-2007. Comparing these observations with the current burst theories confirms the relation between bursting regimes and the accretion states of the system....

  4. Gamma-ray bursts observed by the watch experiment

    DEFF Research Database (Denmark)

    Lund, Niels; Brandt, Søren; Castro-Tirado, A. J.


    After two years in orbit the WATCH instruments on the GRANAT space observatory have localized seven gamma burst sources with better than 1° accuracy. In several cases, follow‐up observations with Schmidt telescopes have been made within a few days. Some of the bursts have also been detected by th...... by the distant space probes PVO and ULYSSES and there are, therefore, good prospects for obtaining much improved positions using the burst arrival times. The existence of the almost concurrent Schmidt plates could then become particularly interesting....

  5. Q-bursts from various distances on the Earth (United States)

    Ogawa, Toshio; Komatsu, Masayuki


    The mechanism of the Q-burst is investigated in the time and frequency domains. Electric fields in the ELF (extremely low frequency) to VLF (very low frequency) range have been observed with a ball antenna since 2003 in Kochi City, Japan (latitude 33.3°north, longitude 133.4°east). Source-to-observer distances (SODs) of Q-bursts are estimated by analyzing the waveforms. It is found as a result that the Q-burst is produced by combination of direct and antipodal pulses from a source lightning stroke occurring all over the world.

  6. Development and control of epileptiform bursting in dissociated cortical cultures (United States)

    Wagenaar, Daniel A.

    Cortical cells in dissociated culture form densely interconnected networks. Within days after plating, neurons become electrically active, and soon after start to synchronize their activity into culture-wide bursts. By growing cultures on multi-electrode arrays (Petri dishes with a grid of substrate-embedded electrodes), their electrical activity can be recorded non-invasively.I developed software, MEABench, for online visualization and analysis of multi-electrode data, and used it to follow the development of cultures obtained from (E18) embryonic rats. Globally synchronized bursting was observed in all but the most sparsely plated cultures. A remarkable range of bursting behaviors was observed, even in cultures with identical plating parameters. Activity patterns varied widely in terms of the frequency, intensity, duration, and degree of temporal clustering of bursts. During the 2nd week in vitro, bursts in many dense cultures clustered into well-defined trains, separated by long periods without bursts. The number of bursts within these 'superbursts' and their spatiotemporal structure were found to be stable for hours or days.Cortical cultures on multi-electrode arrays are ideal for studying two-way communication between biological systems and computers. I designed and built hardware to deliver electrical stimuli in arbitrary patterns, developed software to remove stimulation artifacts from recordings, and studied the efficacy of several voltage-defined and current-defined stimulus waveforms. MEABench can control the stimulator in real-time. Thus, stimuli can be made dependent on a culture's activity with only 15 ms lag-time.We hypothesized that synchronized bursting can dominate activity patterns, because lack of external input puts cultures in a hypersensitive state. Indeed, by feeding cultures a steady stream of stimuli, distributed over many electrodes, bursting could be prevented completely. The number of electrodes required for successful burst control

  7. Quick pace of property acquisitions requires two-stage evaluations

    International Nuclear Information System (INIS)

    Hollo, R.; Lockwood, S.


    The traditional method of evaluating oil and gas reserves may be too cumbersome for the quick pace of oil and gas property acquisition. An acquisition evaluator must decide quickly if a property meets basic purchase criteria. The current business climate requires a two-stage approach. First, the evaluator makes a quick assessment of the property and submits a bid. If the bid is accepted then the evaluator goes on with a detailed analysis, which represents the second stage. Acquisition of producing properties has become an important activity for many independent oil and gas producers, who must be able to evaluate reserves quickly enough to make effective business decisions yet accurately enough to avoid costly mistakes. Independent thus must be familiar with how transactions usually progress as well as with the basic methods of property evaluation. The paper discusses acquisition activity, the initial offer, the final offer, property evaluation, and fair market value

  8. Pacing and Defibrillators in Complex Congenital Heart Disease (United States)

    Chubb, Henry; O’Neill, Mark; Rosenthal, Eric


    Device therapy in the complex congenital heart disease (CHD) population is a challenging field. There is a myriad of devices available, but none designed specifically for the CHD patient group, and a scarcity of prospective studies to guide best practice. Baseline cardiac anatomy, prior surgical and interventional procedures, existing tachyarrhythmias and the requirement for future intervention all play a substantial role in decision making. For both pacing systems and implantable cardioverter defibrillators, numerous factors impact on the merits of system location (endovascular versus non-endovascular), lead positioning, device selection and device programming. For those with Fontan circulation and following the atrial switch procedure there are also very specific considerations regarding access and potential complications. This review discusses the published guidelines, device indications and the best available evidence for guidance of device implantation in the complex CHD population. PMID:27403295

  9. The pace of shifting climate in marine and terrestrial ecosystems

    DEFF Research Database (Denmark)

    Burrows, Michael T.; Schoeman, David S.; Buckley, Lauren B.


    Climate change challenges organisms to adapt or move to track changes in environments in space and time. We used two measures of thermal shifts from analyses of global temperatures over the past 50 years to describe the pace of climate change that species should track: the velocity of climate...... change (geographic shifts of isotherms over time) and the shift in seasonal timing of temperatures. Both measures are higher in the ocean than on land at some latitudes, despite slower ocean warming. These indices give a complex mosaic of predicted range shifts and phenology changes that deviate from...... simple poleward migration and earlier springs or later falls. They also emphasize potential conservation concerns, because areas of high marine biodiversity often have greater velocities of climate change and seasonal shifts....

  10. Trotting, pacing and bounding by a quadruped robot. (United States)

    Raibert, M H


    This paper explores the quadruped running gaits that use the legs in pairs: the trot (diagonal pairs), the pace (lateral pairs), and the bound (front and rear pairs). Rather than study these gaits in quadruped animals, we studied them in a quadruped robot. We found that each of the gaits that use the legs in pairs can be transformed into a common underlying gait, a virtual biped gait. Once transformed, a single set of control algorithms produce all three gaits, with modest parameter variations between them. The control algorithms manipulated rebound height, running speed, and body attitude, while a low-level mechanism coordinated the behavior of the legs in each pair. The approach was tested with laboratory experiments on a four-legged robot. Data are presented that show the details of the running motion for the three gaits and for transitions from one gait to another.

  11. Percutaneously injectable fetal pacemaker: electronics, pacing thresholds, and power budget. (United States)

    Nicholson, Adriana; Chmait, Ramen; Bar-Cohen, Yaniv; Zheng, Kaihui; Loeb, Gerald E


    We are developing a cardiac pacemaker that is designed to be implanted percutaneously into a fetus to treat complete heart block and consequent hydrops fetalis, which is otherwise fatal. One of the most significant considerations for this device is the technical challenges presented by the battery and charging system. The size of the device is limited to about 3 mm in diameter; batteries on this scale have very small charge capacities. The smaller capacity means that the device needs to be designed so that it uses as little current as possible and so that its battery can be recharged wirelessly. We determined the pacing thresholds for a simple relaxation oscillator that can be assembled from discrete, surface mount components and analyzed the power consumption of the device given different electrode configurations and stimulus parameters. An inductive recharging system will be required for some patients; it is feasible within the package constraints and under development.

  12. Can Aquatic Plants Keep Pace with Climate Change?

    Directory of Open Access Journals (Sweden)

    Duarte S. Viana


    Full Text Available The persistence of species may depend upon their capacity to keep pace with climate change. However, dispersal has been ignored in the vast majority of studies that aimed at estimating and predicting range shifts as a response to climate change. Long distance dispersal (LDD in particular might promote rapid range shifts and allow species to track suitable habitat. Many aquatic plant species are dispersed by birds and have the potential to be dispersed over hundreds of kilometers during the bird migration seasons. I argue that such dispersal potential might be critical to allow species to track climate change happening at unprecedented high rates. As a case study, I used dispersal data from three aquatic plant species dispersed by migratory birds to model range shifts in response to climate change projections. By comparing four dispersal scenarios – (1 no dispersal, (2 unlimited dispersal, (3 LDD < 100 km, and (4 LDD mediated by bird migratory movements –, it was shown that, for bird-mediated dispersal, the rate of colonization is sufficient to counterbalance the rate of habitat loss. The estimated rates of colonization (3.2–31.5 km⋅year-1 are higher than, for example, the rate of global warming (previously estimated at 0.42 km⋅year-1. Although further studies are needed, the results suggest that these aquatic plant species can adjust their ranges under a severe climate change scenario. Therefore, investigating the dispersal capacity of species, namely their LDD potential, may contribute to estimate the likelihood of species to keep pace with climate change.

  13. Photon Mass Limits from Fast Radio Bursts

    CERN Document Server

    Bonetti, Luca; Mavromatos, Nikolaos E.; Sakharov, Alexander S.; Sarkisyan-Grinbaum, Edward K.G.; Spallicci, Alessandro D.A.M.


    The frequency-dependent time delays in fast radio bursts (FRBs) can be used to constrain the photon mass, if the FRB redshifts are known, but the similarity between the frequency dependences of dispersion due to plasma effects and a photon mass complicates the derivation of a limit on $m_\\gamma$. The redshift of FRB 150418 has been measured to $\\sim 2$% and its dispersion measure (DM) is known to $\\sim 0.1$%, but the strength of the constraint on $m_\\gamma$ is limited by uncertainties in the modelling of the host galaxy and the Milky Way, as well as possible inhomogeneities in the intergalactic medium (IGM). Allowing for these uncertainties, the recent data on FRB 150418 indicate that $m_\\gamma \\lesssim 1.7 \\times 10^{-14}$ eV c$^{-2}$ ($4.6 \\times 10^{-50}$ kg). In the future, the different redshift dependences of the plasma and photon mass contributions to DM can be used to improve the sensitivity to $m_\\gamma$ if more FRB redshifts are measured. For a fixed fractional uncertainty in the extra-galactic cont...

  14. Fast Radio Bursts from Extragalactic Light Sails

    Energy Technology Data Exchange (ETDEWEB)

    Lingam, Manasvi [John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138 (United States); Loeb, Abraham, E-mail: [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)


    We examine the possibility that fast radio bursts (FRBs) originate from the activity of extragalactic civilizations. Our analysis shows that beams used for powering large light sails could yield parameters that are consistent with FRBs. The characteristic diameter of the beam emitter is estimated through a combination of energetic and engineering constraints, and both approaches intriguingly yield a similar result that is on the scale of a large rocky planet. Moreover, the optimal frequency for powering the light sail is shown to be similar to the detected FRB frequencies. These “coincidences” lend some credence to the possibility that FRBs might be artificial in origin. Other relevant quantities, such as the characteristic mass of the light sail, and the angular velocity of the beam, are also derived. By using the FRB occurrence rate, we infer upper bounds on the rate of FRBs from extragalactic civilizations in a typical galaxy. The possibility of detecting fainter signals is briefly discussed, and the wait time for an exceptionally bright FRB event in the Milky Way is estimated.

  15. Photon mass limits from fast radio bursts (United States)

    Bonetti, Luca; Ellis, John; Mavromatos, Nikolaos E.; Sakharov, Alexander S.; Sarkisyan-Grinbaum, Edward K.; Spallicci, Alessandro D. A. M.


    The frequency-dependent time delays in fast radio bursts (FRBs) can be used to constrain the photon mass, if the FRB redshifts are known, but the similarity between the frequency dependences of dispersion due to plasma effects and a photon mass complicates the derivation of a limit on mγ. The dispersion measure (DM) of FRB 150418 is known to ∼ 0.1%, and there is a claim to have measured its redshift with an accuracy of ∼ 2%, but the strength of the constraint on mγ is limited by uncertainties in the modelling of the host galaxy and the Milky Way, as well as possible inhomogeneities in the intergalactic medium (IGM). Allowing for these uncertainties, the recent data on FRB 150418 indicate that mγ ≲ 1.8 ×10-14 eVc-2 (3.2 ×10-50 kg), if FRB 150418 indeed has a redshift z = 0.492 as initially reported. In the future, the different redshift dependences of the plasma and photon mass contributions to DM can be used to improve the sensitivity to mγ if more FRB redshifts are measured. For a fixed fractional uncertainty in the extra-galactic contribution to the DM of an FRB, one with a lower redshift would provide greater sensitivity to mγ.


    International Nuclear Information System (INIS)

    Sakamoto, T.; Baumgartner, W. H.; Cummings, J. R.; Krimm, H. A.; Barthelmy, S. D.; Gehrels, N.; Markwardt, C. B.; Parsons, A. M.; Tueller, J.; Fenimore, E. E.; Palmer, D. M.; Sato, G.; Stamatikos, M.; Ukwatta, T. N.; Zhang, B.


    We present the second Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts (GRBs), which contains 476 bursts detected by the BAT between 2004 December 19 and 2009 December 21. This catalog (hereafter the BAT2 catalog) presents burst trigger time, location, 90% error radius, duration, fluence, peak flux, time-averaged spectral parameters, and time-resolved spectral parameters measured by the BAT. In the correlation study of various observed parameters extracted from the BAT prompt emission data, we distinguish among long-duration GRBs (L-GRBs), short-duration GRBs (S-GRBs), and short-duration GRBs with extended emission (S-GRBs with E.E.) to investigate differences in the prompt emission properties. The fraction of L-GRBs, S-GRBs, and S-GRBs with E.E. in the catalog are 89%, 8%, and 2%, respectively. We compare the BAT prompt emission properties with the BATSE, BeppoSAX, and HETE-2 GRB samples. We also correlate the observed prompt emission properties with the redshifts for the GRBs with known redshift. The BAT T 90 and T 50 durations peak at 70 s and 30 s, respectively. We confirm that the spectra of the BAT S-GRBs are generally harder than those of the L-GRBs. The time-averaged spectra of the BAT S-GRBs with E.E. are similar to those of the L-GRBs. Whereas, the spectra of the initial short spikes of the S-GRBs with E.E. are similar to those of the S-GRBs. We show that the BAT GRB samples are significantly softer than the BATSE bright GRBs and that the time-averaged E obs peak of the BAT GRBs peaks at 80 keV, which is significantly lower energy than those of the BATSE sample, which peak at 320 keV. The time-averaged spectral properties of the BAT GRB sample are similar to those of the HETE-2 GRB samples. By time-resolved spectral analysis, we find that only 10% of the BAT observed photon indices are outside the allowed region of the synchrotron shock model. We see no obvious observed trend in the BAT T 90 and the observed spectra with redshifts. The T 90

  17. Polarimetry of the Fast Radio Burst Source FRB121102 (United States)

    Michilli, Daniele; Seymour, Andrew; Hessels, Jason W. T.; Spitler, Laura; Gajjar, Vishal; Archibald, Anne; Bower, Geoffrey C.; Chatterjee, Shami; Cordes, Jim; Gourdji, Kelly; Heald, George; Kaspi, Victoria; Law, Casey; Sobey, Charlotte


    Fast radio bursts (FRBs) are millisecond-duration radio flashes of presumably extragalactic origin. FRB121102 is the only FRB known to repeat and the only one with a precise localization. It is co-located with a persistent radio source inside a star-forming region in a dwarf galaxy at z=0.2. While the persistent source is compatible with either a low-luminosity accreting black hole or a very energetic nebula and supernova remnant, the source of the bursts is still a mystery. We present new bursts from FRB121102 detected at relatively high radio frequencies of ~5GHz. These observations allow us to investigate the polarization properties of the bursts, placing new constraints on the environment of FRB121102.

  18. The application of coronal scattering measurements to solar radio bursts

    International Nuclear Information System (INIS)

    Bradford, H.M.


    The interpretation of ground based observations of solar 'plasma frequency' radio bursts has been hampered in the past by an insufficient knowledge of coronal scattering by density inhomogeneities close to the Sun. Calculations based on measuurements of the angular broadening of natural radio sources, and Woo's 1975 measurement of the angular broadening of the telemetry carrier by Helios I near occultation (Woo, 1978), indicate that plasma frequency solar bursts should undergo considerable scattering, at least near the maximum of the sunspot cycle. The calculated displacements of the apparent positions of the bursts are about equal to the observed displacements which have been attributed to the bursts occurring in dense streamers. In order to obtain more scattering data close to the Sun, interferometer measurements of the angular broadening of spacecraft signals are planned, and the important contribution which could be made with large dishes is discussed. (Auth.)

  19. A complete sample of long bright Swift gamma ray bursts. (United States)

    Tagliaferri, Gianpiero; Salvaterra, Ruben; Campana, Sergio; Covino, Stefano; D'Avanzo, Paolo; Fugazza, Dino; Ghirlanda, Giancarlo; Ghisellini, Gabriele; Melandri, Andrea; Nava, Lara; Sbarufatti, Boris; Vergani, Susanna


    Complete samples are the basis of any population study. To this end, we selected a complete subsample of Swift long bright gamma ray bursts (GRBs). The sample, made up of 58 bursts, was selected by considering bursts with favourable observing conditions for ground-based follow-up observations and with the 15-150 keV 1 s peak flux above a flux threshold of 2.6 photons cm(-2) s(-1). This sample has a redshift completeness level higher than 90 per cent. Using this complete sample, we investigate the properties of long GRBs and their evolution with cosmic time, focusing in particular on the GRB luminosity function, the prompt emission spectral-energy correlations and the nature of dark bursts.

  20. The corticospinal responses of metronome-paced, but not self-paced strength training are similar to motor skill training. (United States)

    Leung, Michael; Rantalainen, Timo; Teo, Wei-Peng; Kidgell, Dawson


    The corticospinal responses to skill training may be different to strength training, depending on how the strength training is performed. It was hypothesised that the corticospinal responses would not be different following skill training and metronome-paced strength training (MPST), but would differ when compared with self-paced strength training (SPST). Corticospinal excitability, short-interval intra-cortical inhibition (SICI) and strength and tracking error were measured at baseline and 2 and 4 weeks. Participants (n = 44) were randomly allocated to visuomotor tracking, MPST, SPST or a control group. MPST increased strength by 7 and 18%, whilst SPST increased strength by 12 and 26% following 2 and 4 weeks of strength training. There were no changes in strength following skill training. Skill training reduced tracking error by 47 and 58% at 2 and 4 weeks. There were no changes in tracking error following SPST; however, tracking error reduced by 24% following 4 weeks of MPST. Corticospinal excitability increased by 40% following MPST and by 29% following skill training. There was no change in corticospinal excitability following 4 weeks of SPST. Importantly, the magnitude of change between skill training and MPST was not different. SICI decreased by 41 and 61% following 2 and 4 weeks of MPST, whilst SICI decreased by 41 and 33% following 2 and 4 weeks of skill training. Again, SPST had no effect on SICI at 2 and 4 weeks. There was no difference in the magnitude of SICI reduction between skill training and MPST. This study adds new knowledge regarding the corticospinal responses to skill and MPST, showing they are similar but different when compared with SPST.

  1. Program of all-inclusive care (PACE): past, present, and future. (United States)

    Hirth, Victor; Baskins, Judith; Dever-Bumba, Maureen


    From modest beginnings in 1973 to over 60 programs nationwide, the PACE concept has proven the value of integrated, interdisciplinary-based care for frail older adults. The evolution of PACE and its regulatory and reimbursement model have changed over time, but the principals of care have remained unchanged. Nationally PACE programs are dealing with some of the same challenges they had 30 years ago and yet PACE programs continue to expand and provide care to an ever wider distribution of populations. The looming issue of ever-growing health care expenditures represents another opportunity for PACE to demonstrate its value while providing a level of quality beyond what could normally be provided by typical Medicare and Medicaid payments for similar conditions and patient characteristics. The future for PACE includes a number of possibilities including flexibility in financing and reimbursement, design changes to work with community-based physicians, potential eligibility adjustments, and growth of rural PACE. The PACE model has clearly demonstrated that in a debilitated, frail population in whom health care expenses would be expect to be high, a combination of team care, managed health care services, and care coordination can lead to both improved health outcomes and reduced expenses over time.

  2. Effects of permanent dual chamber pacing on myocardial perfusion in symptomatic hypertrophic cardiomyopathy

    NARCIS (Netherlands)

    Posma, JL; Blanksma, PK; VanderWall, EE; Vaalburg, W; Crijns, HJGM; Lie, KI


    Objective-Angina and the presence of myocardial ischaemia are common in hypertrophic cardiomyopathy. Dual chamber pacing results in clinical improvement in these patients. This study evaluates the effects of permanent dual chamber pacing on absolute regional myocardial perfusion and perfusion

  3. Beneficial effects of biventricular pacing in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay


    Rinaldi, C A; Bucknall, C A; Gill, J S


    The beneficial use of biventricular pacing is reported in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay. This resulted in improvements in symptomatic status and exercise tolerance that may be related to cardiac resynchronisation. The improvement in symptoms by biventricular pacing in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay is previously undocumented and requires further investigation.

  4. Cricket pace bowling: The trade-off between optimising knee angle ...

    African Journals Online (AJOL)

    Objective. To investigate the relationship between three-dimensional (3D) knee kinematics during pace bowling action, injury incidence and bowling performance at the start and end of a cricket season. Methods. Knee angle and ball release (BR) speed of injury-free premier league (club level) cricket pace bowlers over the ...

  5. Achievement of Women in a Self-paced Earth Science Course (United States)

    Mott, Charles J.


    Performance differences were not significant between men and women in Earth Science classes with fixed assignment deadlines, nor were achievement differences significant for women in self-paced sections compared to fixed deadline men or women. Men performed higher than women in self-paced groups, and higher than men or women in other learning…

  6. Atrioventricular Cross-Talk Leading to Ventricular Pacing Inhibition in a Dual-Chamber ICD

    Directory of Open Access Journals (Sweden)

    Luuk Debie


    Full Text Available We report atrio-ventricular cross talk in a patient with a dual chamber ICD leading to ventricular pacing inhibition. This was observed in an ICD without the ventricular safety pace option, which normally is a sufficient protection against this phenomenon. Cross talk could be prevented effectively by reprogramming ventricular sensitivity to a less sensitive setting.

  7. The Relationship between Right Ventricular Pacing Voltage and QRS Complex Duration

    Czech Academy of Sciences Publication Activity Database

    Vančura, V.; Wichterle, D.; Brabec, Marek; Bytešník, J.; Lefflerová, K.; Kautzner, J.


    Roč. 30, č. 5 (2009), s. 517-527 ISSN 0967-3334 Institutional research plan: CEZ:AV0Z10300504 Keywords : cardiac pacing * QRS complex duration * pacing voltag * vectorcardiography * nonlinear regression analysis Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.430, year: 2009

  8. Integrating Self-Paced Mobile Learning into Language Instruction: Impact on Reading Comprehension and Learner Satisfaction (United States)

    Wang, Yen-Hui


    The study integrated self-paced mobile learning (m-learning) into a language course, and examined what impacts were being produced on learners' reading comprehension and student satisfaction resulting from the instruction with m-learning integration. The self-paced, learner-centered mobile learning integration instruction (MLI) was compared with…

  9. Improvement of pacing induced regional myocardial ischemia by Solcoseryl in conscious dogs with coronary stenosis. (United States)

    Shimada, T; Sasayama, S; Takahashi, M; Osakada, G; Kawai, C


    The effects of Solcoseryl on regional myocardial function were studied in 5 conscious dogs with partial coronary constriction, in which temporary ischemia was induced by rapid cardiac pacing. During the coronary artery constriction, the percent shortening of the ischemic segment decreased by 9%. When the heart rate was increased by pacing, the percent shortening of the ischemic segments was further reduced by 57%. On cessation of cardiac pacing, the early potentiation of dP/dt and of control segment shortening became evident and was followed by exponential decay in the subsequent several beats. In the ischemic segment, the percent shortening was significantly improved in the first post-pacing beat but was more severely depressed at five seconds. Thirty minutes after administration of Solcoseryl, the cardiac pacing was repeated in the same manner but the pacing-induced hypokinesia of the ischemic segment were less marked, the percent shortening being at an average of 9.1% during control pacing and 12.7% during the second pacing after Solcoseryl (p less than 0.05). Postpacing deterioration of the ischemic segment shortening was also significantly improved from 9.8 to 11.8% at 5 seconds (p less than 0.05). These findings indicate that Solcoseryl exerts protective effects on the ischemic myocardium by promoting a rapid recovery from ischemia, probably due to the improvement of oxygen utility through activated cellular respiration.

  10. New method for cardiac resynchronization therapy: Transapical endocardial lead implantation for left ventricular free wall pacing

    NARCIS (Netherlands)

    I. Kassai (Imre); C. Foldesi (Csaba); A. Szekely (Andrea); T. Szili-Torok (Tamas)


    textabstractCoronary sinus lead placement for transvenous left ventricular (LV) pacing in cardiac resynchronization therapy (CRT) has a significant failure rate at implant and a significant dislocation rate during follow-up. For these patients, epicardial pacing lead implantation is the most

  11. Right ventricular pacing and the risk of heart failure in implantable cardioverter-defibrillator patients

    NARCIS (Netherlands)

    Smit, Marcelle D.; Van Dessel, Pascal F. H. M.; Nieuwland, Wybe; Wiesfeld, Ans C. P.; Tan, Eng S.; Anthonio, Rutger L.; Van Erven, Lieselot; Van Veldhuisen, Dirk J.; Van Gelder, Isabelle C.


    BACKGROUND Right ventricular (RV) pacing in implantable cardioverter-defibrillator (ICD) patients may have detrimental effects on morbidity and mortality, in particular by inducing heart failure (HF). OBJECTIVE We investigated whether RV pacing increases the risk of HF in an asymptomatic ICD

  12. Keeping Pace with K-12 Online & Blended Learning: An Annual Review of Policy and Practice, 2013 (United States)

    Watson, John; Murin, Amy; Vashaw, Lauren; Gemin, Butch; Rapp, Chris


    This is the 10th annual "Keeping Pace" report. "Keeping Pace" has several goals: (1) add to the body of knowledge about online education policy and practice, and make recommendations for advances; (2) serve as a reference source for information about programs and policies across the country, both for policymakers and…

  13. Burst Statistics Using the Lag-Luminosity Relationship (United States)

    Band, D. L.; Norris, J. P.; Bonnell, J. T.


    Using the lag-luminosity relation and various BATSE catalogs we create a large catalog of burst redshifts, peak luminosities and emitted energies. These catalogs permit us to evaluate the lag-luminosity relation, and to study the burst energy distribution. We find that this distribution can be described as a power law with an index of alpha = 1.76 +/- 0.05 (95% confidence), close to the alpha = 2 predicted by the original quasi-universal jet model.

  14. Testing the Gamma-Ray Burst Energy Relationships (United States)

    Band, David L.; Preece, Robert D.


    Building on Nakar & Piran's analysis of the Amati relation relating gamma-ray burst peak energies E(sub p) and isotropic energies E(sub iso ) we test the consistency of a large sample of BATSE bursts with the Amati and Ghirlanda (which relates peak energies and actual gamma-ray energies E(sub gamma)) relations. Each of these relations can be exp ressed as a ratio of the different energies that is a function of red shift (for both the Amati and Ghirlanda relations) and beaming fraction f(sub B) (for the Ghirlanda relation). The most rigorous test, whic h allows bursts to be at any redshift, corroborates Nakar & Piran's r esult - 88% of the BATSE bursts are inconsistent with the Amati relat ion - while only l.6% of the bursts are inconsistent with the Ghirlan da relation if f(sub B) = 1. Modelling the redshift distribution resu lts in an energy ratio distribution for the Amati relation that is sh ifted by an order of magnitude relative to the observed distributions; any sub-population satisfying the Amati relation can comprise at mos t approx. 18% of our burst sample. A similar analysis of the Ghirland a relation depends sensitively on the beaming fraction distribution f or small values of f(sub B); for reasonable estimates of this distrib ution about a third of the burst sample is inconsistent with the Ghir landa relation. Our results indicate that these relations are an artifact of the selection effects of the burst sample in which they were f ound; these selection effects may favor sub-populations for which the se relations are valid.

  15. Burst suppression in sleep in a routine outpatient EEG

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    Ammar Kheder


    Full Text Available Burst suppression (BS is an electroencephalogram (EEG pattern that is characterized by brief bursts of spikes, sharp waves, or slow waves of relatively high amplitude alternating with periods of relatively flat EEG or isoelectric periods. The pattern is usually associated with coma, severe encephalopathy of various etiologies, or general anesthesia. We describe an unusual case of anoxic brain injury in which a BS pattern was seen during behaviorally defined sleep during a routine outpatient EEG study.

  16. Review of GRANAT observations of gamma-ray bursts

    DEFF Research Database (Denmark)

    Terekhov, O.; Denissenko, D.; Sunyaev, R.


    The GRANAT observatory was launched into a high apogee orbit on 1 December, 1989. Three instruments onboard GRANAT - PHEBUS, WATCH and SIGMA are able to detect gamma-ray bursts in a very broad energy range from 6 keV up to 100 MeV. Over 250 gamma-ray bursts were detected. We discuss the results o...... the SIGMA telescope field of view are reviewed....

  17. Neutron star mergers and gamma-ray bursts (United States)

    Narayan, Ramesh


    Under the support of grant NAG 5-1904, we have carried out research on several topics related to gamma-ray bursts (GRB's). In our proposal, we stated that we would study three topics: (1) fireball evolution; (2) neutron star mergers; and (3) statistics of bursts. We have completed a significant amount of work in each of these areas. Resulting papers from this work are presented.

  18. Real Life Science with Dandelions and Project BudBurst

    Directory of Open Access Journals (Sweden)

    Katherine A. Johnson


    Full Text Available Project BudBurst is a national citizen-science project that tracks bloom times and other phenological data for plants across the country. Data from Project BudBurst are being used to measure the effects of climate change. Students can participate in this project by watching any of the plants on the list, including the common dandelion, which makes the program easy and accessible to everyone.

  19. High repetition rate burst-mode spark gap

    International Nuclear Information System (INIS)

    Faltens, A.; Reginato, L.; Hester, R.; Chesterman, A.; Cook, E.; Yokota, T.; Dexter, W.


    Results are presented on the design and testing of a pressurized gas blown spark gap switch capable of high repetition rates in a burst mode of operation. The switch parameters which have been achieved are as follows: 220-kV, 42-kA, a five pulse burst at 1-kHz, 12-ns risetime, 2-ns jitter at a pulse width of 50-ns

  20. Emission Patterns of Solar Type III Radio Bursts: Stereoscopic Observations (United States)

    Thejappa, G.; MacDowall, R.; Bergamo, M.


    Simultaneous observations of solar type III radio bursts obtained by the STEREO A, B, and WIND spacecraft at low frequencies from different vantage points in the ecliptic plane are used to determine their directivity. The heliolongitudes of the sources of these bursts, estimated at different frequencies by assuming that they are located on the Parker spiral magnetic field lines emerging from the associated active regions into the spherically symmetric solar atmosphere, and the heliolongitudes of the spacecraft are used to estimate the viewing angle, which is the angle between the direction of the magnetic field at the source and the line connecting the source to the spacecraft. The normalized peak intensities at each spacecraft Rj = Ij /[Sigma]Ij (the subscript j corresponds to the spacecraft STEREO A, B, and WIND), which are defined as the directivity factors are determined using the time profiles of the type III bursts. It is shown that the distribution of the viewing angles divides the type III bursts into: (1) bursts emitting into a very narrow cone centered around the tangent to the magnetic field with angular width of approximately 2 deg and (2) bursts emitting into a wider cone with angular width spanning from [approx] -100 deg to approximately 100 deg. The plots of the directivity factors versus the viewing angles of the sources from all three spacecraft indicate that the type III emissions are very intense along the tangent to the spiral magnetic field lines at the source, and steadily fall as the viewing angles increase to higher values. The comparison of these emission patterns with the computed distributions of the ray trajectories indicate that the intense bursts visible in a narrow range of angles around the magnetic field directions probably are emitted in the fundamental mode, whereas the relatively weaker bursts visible to a wide range of angles are probably emitted in the harmonic mode.


    Directory of Open Access Journals (Sweden)

    Zahro Varisna Rohmadani


    Full Text Available Penelitian ini bertujuan untuk mengetahui efektivitas metode future pacing hypnotherapy dalam menurunkan tingkat kecemasan pada mahasiswa baru. Subjek penelitian adalah 20 mahasiswa/i baru, 10 mahasiswa di kelompok eksperimen dan 10 mahasiswa di kelompok kontrol. Peserta mendapatkan penanganan untuk penurunan kecemasan dengan metode berupa future pacing hypnotherapy. Metode analisis data yang digunakan adalah statistik nonparametrik teknik Wilcoxon Signed Rank Test untuk menguji perbedaan skor cemas kelompok subjek saat pretest dan posttest serta Mann Whitney U untuk melihat perbedaan penurunan kecemasan pada kelompok eksperimen dan kelompok kontrol. Hasil Wilcoxon Signed Rank Test menunjukkan bahwa future pacing hypnotherapy efektif dalam menurunkan kecemasan dengan p=0,012. Sedangkan hasil Mann Whitney U menunjukkan bahwa future pacing hypnotherapy efektif dalam menurunkan kecemasan dengan p=0,003 dan kelompok eksperimen mengalami penurunan kecemasan yang lebih besar dengan mean rank = 14,25.Kata kunci : future pacing hypnotherapy, kecemasan, mahasiswa baru

  2. Low-cost implementation of a self-paced treadmill by using a commercial depth sensor. (United States)

    Kim, Jonghyun; Gravunder, Andrew; Stanley, Christopher J; Park, Hyung-Soon


    A self-paced treadmill that can simulate overground walking has the potential to improve the effectiveness of treadmill training for gait rehabilitation. We have implemented a self-paced treadmill without the need for expensive equipment such as a motion capture system and an instrumented treadmill. For this, an inexpensive depth sensor, ASUS XtionTM, substitutes for the motion capture system, and a low-cost commercial treadmill is considered as the platform of the self-paced treadmill. The proposed self-paced treadmill is also convenient because the depth sensor does not require markers placed on user's body. Through pilot tests with two healthy subjects, it is quantitatively and qualitatively verified that the proposed self-paced treadmill achieves similar performance as one which utilizes a commercial motion capture system (VICON) as well as an instrumented treadmill.

  3. Rock Burst Mechanics: Insight from Physical and Mathematical Modelling

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    J. Vacek


    Full Text Available Rock burst processes in mines are studied by many groups active in the field of geomechanics. Physical and mathematical modelling can be used to better understand the phenomena and mechanisms involved in the bursts. In the present paper we describe both physical and mathematical models of a rock burst occurring in a gallery of a coal mine.For rock bursts (also called bumps to occur, the rock has to possess certain particular rock burst properties leading to accumulation of energy and the potential to release this energy. Such materials may be brittle, or the rock burst may arise at the interfacial zones of two parts of the rock, which have principally different material properties (e.g. in the Poíbram uranium mines.The solution is based on experimental and mathematical modelling. These two methods have to allow the problem to be studied on the basis of three presumptions:· the solution must be time dependent,· the solution must allow the creation of cracks in the rock mass,· the solution must allow an extrusion of rock into an open space (bump effect. 

  4. The host galaxy of a fast radio burst. (United States)

    Keane, E F; Johnston, S; Bhandari, S; Barr, E; Bhat, N D R; Burgay, M; Caleb, M; Flynn, C; Jameson, A; Kramer, M; Petroff, E; Possenti, A; van Straten, W; Bailes, M; Burke-Spolaor, S; Eatough, R P; Stappers, B W; Totani, T; Honma, M; Furusawa, H; Hattori, T; Morokuma, T; Niino, Y; Sugai, H; Terai, T; Tominaga, N; Yamasaki, S; Yasuda, N; Allen, R; Cooke, J; Jencson, J; Kasliwal, M M; Kaplan, D L; Tingay, S J; Williams, A; Wayth, R; Chandra, P; Perrodin, D; Berezina, M; Mickaliger, M; Bassa, C


    In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe, and including all of the so-called 'missing baryons'. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.

  5. A Retroactive-Burst Framework for Automated Intrusion Response System

    Directory of Open Access Journals (Sweden)

    Alireza Shameli-Sendi


    Full Text Available The aim of this paper is to present an adaptive and cost-sensitive model to prevent security intrusions. In most automated intrusion response systems, response selection is performed locally based on current threat without using the knowledge of attacks history. Another challenge is that a group of responses are applied without any feedback mechanism to measure the response effect. We address these problems through retroactive-burst execution of responses and a Response Coordinator (RC mechanism, the main contributions of this work. The retroactive-burst execution consists of several burst executions of responses with, at the end of each burst, a mechanism for measuring the effectiveness of the applied responses by the risk assessment component. The appropriate combination of responses must be considered for each burst execution to mitigate the progress of the attack without necessarily running the next round of responses, because of the impact on legitimate users. In the proposed model, there is a multilevel response mechanism. To indicate which level is appropriate to apply based on the retroactive-burst execution, we get help from a Response Coordinator mechanism. The applied responses can improve the health of Applications, Kernel, Local Services, Network Services, and Physical Status. Based on these indexes, the RC gives a general overview of an attacker’s goal in a distributed environment.

  6. Investigation of Burst Pressures in PWR Primary Pressure Boundary Components

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    Ihn Namgung


    Full Text Available In a reactor coolant system of a nuclear power plant (NPP, an overpressure protection system keeps pressure in the loop within 110% of design pressure. However if the system does not work properly, pressure in the loop could elevate hugely in a short time. It would be seriously disastrous if a weak point in the pressure boundary component bursts and releases radioactive material within the containment; and it may lead to a leak outside the containment. In this study, a gross deformation that leads to a burst of pressure boundary components was investigated. Major components in the primary pressure boundary that is structurally important were selected based on structural mechanics, then, they were used to study the burst pressure of components by finite element method (FEM analysis and by number of closed forms of theoretical relations. The burst pressure was also used as a metric of design optimization. It revealed which component was the weakest and which component had the highest margin to bursting failure. This information is valuable in severe accident progression prediction. The burst pressures of APR-1400, AP1000 and VVER-1000 reactor coolant systems were evaluated and compared to give relative margins of safety.

  7. Gamma Ray Burst Discoveries by the Swift Mission (United States)

    Gehrels, Neil


    Gamma-ray bursts are among the most fascinating occurrences in the cosmos. They are thought to be the birth cries of black holes throughout the universe. The NASA swift mission is an innovative new multiwavelength observatory designed to determine the origin of bursts and use them to probe the early Universe. Swift is now in orbit since November 20, 2004 and all hardware is performing well. A new-technology wide-field gamma-ray camera is detecting a hundred bursts per year. sensitive narrow-field X-ray and uv/optical telescopes, built in collaboration with UK and Italian partners, are pointed at the burst location in 50-100 sec by an autonomously controlled "swift" spacecraft. For each burst, arcsec positions are determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Information is also rapidly sent to the ground to a team of more than 50 observers at telescopes around the world. The first year of findings from the mission will be presented. There has been a break-through in the longstanding mystery of short GRBs; they appear to be caused by merging neutron stars. High redshift bursts have been detected leading to a better understanding of star formation rates and distant galaxy environments. GRBs have been found with giant X-ray flares occurring in their afterglow.

  8. Successive X-ray bursts from accreting neutron stars (United States)

    Taam, Ronald E.; Woosley, S. E.; Weaver, T. A.; Lamb, D. Q.


    The evolution of a neutron star undergoing a series of thermonuclear flashes in its accreted hydrogen-rich layer has been numerically followed to determine the effects of the history of the neutron star's thermal and compositional structure on the properties of the emitted X-ray bursts. Burst characteristics are studied for a range of mass accretion rates, CNO abundances in the accreted matter, and initial thermal states of the underlying neutron star core; the bursts exhibit erratic behavior for low CNO metal abundances and cool neutron star cores, with the burst recurrence time scales varying by 1-2 orders of magnitude. There is typically a continued presence of a substantial amount of unburnt hydrogen in the accreted layer throughout the series of the X-ray burst events. Convective mixing during the quiescent phase leads to the inward transport of helium to high densities and eventually to the initiation of the next outburst. The resulting bursts can be weak and, in such cases, are characterized by short recurrence time scales (1-2 hr), low peak luminosities (0.1-0.2 times the Eddington value), and low alpha-values (about 20).

  9. Utility of the surface electrocardiogram for confirming right ventricular septal pacing: validation using electroanatomical mapping. (United States)

    Burri, Haran; Park, Chan-Il; Zimmermann, Marc; Gentil-Baron, Pascale; Stettler, Carine; Sunthorn, Henri; Domenichini, Giulia; Shah, Dipen


    When targeting the interventricular septum during pacemaker implantation, the lead may inadvertently be positioned on the anterior wall due to imprecise fluoroscopic landmarks. Surface electrocardiogram (ECG) criteria of the paced QRS complex (e.g. negativity in lead I) have been proposed to confirm a septal position, but these criteria have not been properly validated. Our aim was to investigate whether the paced QRS complex may be used to confirm septal lead position. Anatomical reconstruction of the right ventricle was performed using a NavX® system in 31 patients (70 ± 11 years, 26 males) to validate pacing sites. Surface 12-lead ECGs were analysed by digital callipers and compared while pacing from a para-Hissian position, from the mid-septum, and from the anterior free wall. Duration of the QRS complex was not significantly shorter when pacing from the mid-septum compared with the other sites. QRS axis was significantly less vertical during mid-septal pacing (18 ± 51°) compared with para-Hissian (38 ± 37°, P = 0.028) and anterior (53 ± 55°, P = 0.003) pacing, and QRS transition was intermediate (4.8 ± 1.3 vs. 3.8 ± 1.3, P < 0.001, and vs. 5.4 ± 0.9, P = 0.045, respectively), although no cut-offs could reliably distinguish sites. A negative QRS or the presence of a q-wave in lead I tended to be more frequent with anterior than with mid-septal pacing (9/31 vs. 3/31, P = 0.2 and 8/31 vs. 1/31, P = 1.0, respectively). No single ECG criterion could reliably distinguish pacing the mid-septum from the anterior wall. In particular, a negative QRS complex in lead I is an inaccurate criterion for validating septal pacing.

  10. Neuronal networks and energy bursts in epilepsy. (United States)

    Wu, Y; Liu, D; Song, Z


    Epilepsy can be defined as the abnormal activities of neurons. The occurrence, propagation and termination of epileptic seizures rely on the networks of neuronal cells that are connected through both synaptic- and non-synaptic interactions. These complicated interactions contain the modified functions of normal neurons and glias as well as the mediation of excitatory and inhibitory mechanisms with feedback homeostasis. Numerous spread patterns are detected in disparate networks of ictal activities. The cortical-thalamic-cortical loop is present during a general spike wave seizure. The thalamic reticular nucleus (nRT) is the major inhibitory input traversing the region, and the dentate gyrus (DG) controls CA3 excitability. The imbalance between γ-aminobutyric acid (GABA)-ergic inhibition and glutamatergic excitation is the main disorder in epilepsy. Adjustable negative feedback that mediates both inhibitory and excitatory components affects neuronal networks through neurotransmission fluctuation, receptor and transmitter signaling, and through concomitant influences on ion concentrations and field effects. Within a limited dynamic range, neurons slowly adapt to input levels and have a high sensitivity to synaptic changes. The stability of the adapting network depends on the ratio of the adaptation rates of both the excitatory and inhibitory populations. Thus, therapeutic strategies with multiple effects on seizures are required for the treatment of epilepsy, and the therapeutic functions on networks are reviewed here. Based on the high-energy burst theory of epileptic activity, we propose a potential antiepileptic therapeutic strategy to transfer the high energy and extra electricity out of the foci. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  11. Light Dawns on Dark Gamma-ray Bursts (United States)


    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  12. The utility of atrial pacing for identifying the electrical breakthrough sites between the left atrium and pulmonary veins

    Directory of Open Access Journals (Sweden)

    Shinya Sugiura, MD


    Conclusions: This pacing method may help to identify whether EBSs are located in the anterior Lt.PVs. Improved recognition of EBSs through pacing from different sites would be helpful for achieving PV isolation.

  13. The role of temporary biventricular pacing in the cardiac surgical patient with severely reduced left ventricular systolic function. (United States)

    Evonich, Rudolph F; Stephens, John C; Merhi, William; Dukkipati, Srinivas; Tepe, Nicholas; Shannon, Francis; Altshuler, Jeffrey; Sakwa, Marc; Bassett, Joseph; Hanson, Eric; Boura, Judy; O'Neill, William W; Haines, David E


    The objective was to evaluate the effects of atrial synchronous biventricular pacing in postoperative patients with severe cardiomyopathy. Atrial synchronous biventricular pacing epicardial leads were placed during cardiac surgery in patients with an ejection fraction of 30% or less. Patients were randomized to usual care pacing, the mode determined by the surgeon (excluding atrial synchronous biventricular pacing) with a preference for no pacing or atrial pacing (atrial inhibited pacing); atrial synchronous right ventricular pacing; or atrial synchronous biventricular pacing. Pacing was continued until cessation of hemodynamic support. At 12 hours postoperatively, patients were randomly tested in each mode (atrial inhibited, atrial synchronous right ventricular, and atrial synchronous biventricular pacing), and thermodilution outputs were measured. Forty subjects were randomized. Groups were similar in age (66 +/- 11 years), gender (85% were male), ejection fraction (23% +/- 6%), QRS duration (111 +/- 30 ms), and surgical indication. There was no difference in stroke index or cardiac index at 12 hours, duration of inotropic or intra-aortic balloon pump support, intensive care unit, or hospital length of stay. On comparative crossover testing, stroke volume was similar with atrial inhibited pacing and atrial synchronous biventricular pacing (59.3 +/- 13.4 vs 57 +/- 12.1, respectively, P = not significant); however, atrial synchronous right ventricular pacing was inferior (56 +/- 12.9, P or= 5%), whereas 41% had a 5% or greater decrease in stroke volume. Pacing mode affects stroke volume in patients with severe cardiomyopathy. Atrial synchronous biventricular pacing was helpful in a minority, but in 41% it compromised stroke volume.

  14. Arachidonic acid triggers an oxidative burst in leukocytes

    Directory of Open Access Journals (Sweden)

    Pompeia C.


    Full Text Available The change in cellular reducing potential, most likely reflecting an oxidative burst, was investigated in arachidonic acid- (AA stimulated leukocytes. The cells studied included the human leukemia cell lines HL-60 (undifferentiated and differentiated into macrophage-like and polymorphonuclear-like cells, Jurkat and Raji, and thymocytes and macrophages from rat primary cultures. The oxidative burst was assessed by nitroblue tetrazolium reduction. AA increased the oxidative burst until an optimum AA concentration was reached and the burst decreased thereafter. In the leukemia cell lines, optimum concentration ranged from 200 to 400 µM (up to 16-fold, whereas in rat cells it varied from 10 to 20 µM. Initial rates of superoxide generation were high, decreasing steadily and ceasing about 2 h post-treatment. The continuous presence of AA was not needed to stimulate superoxide generation. It seems that the NADPH oxidase system participates in AA-stimulated superoxide production in these cells since the oxidative burst was stimulated by NADPH and inhibited by N-ethylmaleimide, diphenyleneiodonium and superoxide dismutase. Some of the effects of AA on the oxidative burst may be due to its detergent action. There apparently was no contribution of other superoxide-generating systems such as xanthine-xanthine oxidase, cytochromes P-450 and mitochondrial electron transport chain, as assessed by the use of inhibitors. Eicosanoids and nitric oxide also do not seem to interfere with the AA-stimulated oxidative burst since there was no systematic effect of cyclooxygenase, lipoxygenase or nitric oxide synthase inhibitors, but lipid peroxides may play a role, as indicated by the inhibition of nitroblue tetrazolium reduction promoted by tocopherol.

  15. Stress Effects on Stop Bursts in Five Languages

    Directory of Open Access Journals (Sweden)

    Marija Tabain


    Full Text Available This study examines the effects of stress on the stop burst in five languages differing in number of places of articulation, as reflected in burst duration, spectral centre of gravity, and ­spectral standard deviation. The languages studied are English (three places of articulation /p t k/, the Indonesian language Makasar (four places /p t c k/, and the Central Australian languages ­Pitjantjatjara, Warlpiri (both five places /p t ʈ c k/, and Arrernte (six places /p t̪ t ʈ c k/. We find that languages differ in how they manifest stress on the consonant, with Makasar not ­showing any effect of stress at all, and Warlpiri showing an effect on burst duration, but not on the ­spectral measures. For the other languages, the velar /k/ has a “darker” quality (i.e., lower spectral centre of gravity, and/or a less diffuse spectrum (i.e., lower standard deviation under stress; while the alveolar /t/ has a “lighter” quality under stress. In addition, the dental /t̪/ has a more diffuse spectrum under stress. We suggest that this involves enhancement of the features [grave] and [diffuse] under stress, with velars being [+grave] and [–diffuse], alveolars being [–grave], and dentals being [+diffuse]. We discuss the various possible spectral effects of enhancement of these features. Finally, in the languages with five or six places of articulation, the stop burst is longer only for the palatal /c/ and the velar /k/, which have intrinsically long burst durations, and not for the anterior coronals /t̪ t ʈ/, which have intrinsically short burst durations. We suggest that in these systems, [burst duration] is a feature that separates these two groups of consonants.

  16. Echocardiographic estimation of acute haemodynamic response during optimization of multisite pace-maker using different pacing modalities and atrioventricular delays

    Directory of Open Access Journals (Sweden)

    Šalinger-Martinović Sonja


    Full Text Available Background/Aim. Cardiac resynchronization therapy (CRT improves ventricular dyssynchrony and is associated with an improvement in symptoms, quality of life and prognosis in patients with severe heart failure and intraventricular conduction delay. Different pacing modalities produce variable activation patterns and may be a cause of different haemodynamic changes. The aim of our study was to investigate acute haemodynamic changes with different CRT configurations during optimization procedure. Methods. This study included 30 patients with severe left ventricular systolic dysfunction and left bundle branch block with wide QRS (EF 24.33 ± 3.7%, QRS 159 ± 17.3 ms, New York Heart Association III/IV 25/5 with implanted CRT device. The whole group of patients had severe mitral regurgitation in order to measure dP/dt. After implantation and before discharge all the patients underwent optimization procedure guided by Doppler echocardiography. Left and right ventricular pre-ejection intervals (LVPEI and RVPEI, interventricular mechanical delay (IVD and the maximal rate of ventricular pressure rise during early systole (max dP/dt were measured during left and biventricular pacing with three different atrioventricular (AV delays. Results. After CRT device optimization, optimal AV delay and CRT mode were defined. Left ventricular pre-ejection intervals changed from 170.5 ± 24.6 to 145.9 ± 9.5 (p < 0.001, RVPEI from 102.4 ± 15.9 to 119.8 ± 10.9 (p < 0.001, IVD from 68.1 ± 18.3 to 26.5 ± 8.2 (p < 0.001 and dP/dt from 524.2 ± 67 to 678.2 ± 88.5 (p < 0.01. Conclusion. In patients receiving CRT echocardiographic assessment of the acute haemodynamic response to CRT is a useful tool in optimization procedure. The variability of Doppler parameters with different CRT modalities emphasizes the necessity of individualized approach in optimization procedure.

  17. Cardiomyopathy induced by artificial cardiac pacing: myth or reality sustained by evidence? (United States)

    Ferrari, Andrés Di Leoni; Borges, Anibal Pires; Albuquerque, Luciano Cabral; Sussenbach, Carolina Pelzer; da Rosa, Priscila Raupp; Piantá, Ricardo Medeiros; Wiehe, Mario; Goldani, Marco Antônio


    Implantable cardiac pacing systems are a safe and effective treatment for symptomatic irreversible bradycardia. Under the proper indications, cardiac pacing might bring significant clinical benefit. Evidences from literature state that the action of the artificial pacing system, mainly when the ventricular lead is located at the apex of the right ventricle, produces negative effects to cardiac structure (remodeling, dilatation) and function (dissinchrony). Patients with previously compromised left ventricular function would benefit the least with conventional right ventricle apical pacing, and are exposed to the risk of developing higher incidence of morbidity and mortality for heart failure. However, after almost 6 decades of cardiac pacing, just a reduced portion of patients in general would develop these alterations. In this context, there are not completely clear some issues related to cardiac pacing and the development of this cardiomyopathy. Causality relationships among QRS widening with a left bundle branch block morphology, contractility alterations within the left ventricle, and certain substrates or clinical (previous systolic dysfunction, structural heart disease, time from implant) or electrical conditions (QRS duration, percentage of ventricular stimulation) are still subjecte of debate. This review analyses contemporary data regarding this new entity, and discusses alternatives of how to use cardiac pacing in this context, emphasizing cardiac resynchronization therapy. PMID:25372916

  18. Pacing-induced congenital heart defects assessed by OCT (Conference Presentation) (United States)

    Ford, Stephanie M.; McPheeters, Matt T.; Wang, Yves T.; Gu, Shi; Doughman, Yong Qiu; Strainic, James P.; Rollins, Andrew M.; Watanabe, Michiko; Jenkins, Michael W.


    The role of hemodynamics in early heart development is poorly understood. In order to successfully assess the impact of hemodynamics on development, we need to monitor and perturb blood flow, and quantify the resultant effects on morphology. Here, we have utilized cardiac optical pacing to create regurgitant flow in embryonic hearts and OCT to quantify regurgitation percentage and resultant morphology. Embryonic quail in a shell-less culture were optically paced at 3 Hz (well above the intrinsic rate or 1.33-1.67 Hz) on day 2 of development (3-4 weeks human) for 5 minutes. The pacing fatigued the heart and led to a prolonged period (> 1 hour) of increased regurgitant flow. Embryos were kept alive until day 3 (cardiac looping - 4-5 weeks human) or day 8 (4 chambered heart - 8 weeks human) to quantify resultant morphologic changes with OCT. All paced embryos imaged at day 3 displayed cardiac defects. The extent of regurgitant flow immediately after pacing was correlated with cardiac cushion size 24-hours post pacing (p-value cardio-facial/DiGeorge syndrome models suggesting that hemodynamics plays a role in these syndromes as well. Utilizing OCT and optical pacing to understand hemodynamics in development is an important step towards determining CHD mechanisms and ultimately developing earlier treatments.

  19. Cardiac optogenetic pacing in drosophila melanogaster using red-shifted opsins (Conference Presentation) (United States)

    Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao


    Electrical pacing is the current gold standard for investigation of mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, this method requires an invasive surgical procedure to implant the pacing electrodes. Recently, optogenetic pacing has been developed as an alternative, non-invasive method for heartbeat pacing in animals. It induces heartbeats by shining pulsed light on transgene-generated microbial opsins which in turn activate light gated ion channels in animal hearts. However, commonly used opsins, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we expressed recently engineered red-shifted opsins, ReaChR and CsChrimson, in the heart of a well-developed animal model, Drosophila melanogaster, for the first time. Optogenetic pacing was successfully conducted in both ReaChR and CsChrimson flies at their larval, pupal, and adult stages using 617 nm excitation light pulse, enabling a much deeper tissue penetration compared to blue stimulation light. A customized high speed and ultrahigh resolution OCM system was used to non-invasively monitor the heartbeat pacing in Drosophila. Compared to previous studies on optogenetic pacing of Drosophila, higher penetration depth of optogenetic excitation light was achieved in opaque late pupal flies. Lower stimulating power density is needed for excitation at each developmental stage of both groups, which improves the safety of this technique for heart rhythm studies.

  20. A Closer Look at Split Visual Attention in System- and Self-Paced Instruction in Multimedia Learning (United States)

    Schmidt-Weigand, Florian; Kohnert, Alfred; Glowalla, Ulrich


    Two experiments examined visual attention distribution in learning from text and pictures. Participants watched a 16-step multimedia instruction on the formation of lightning. In Experiment 1 (N=90) the instruction was system-paced (fast, medium, slow pace), while it was self-paced in Experiment 2 (N=31). In both experiments the text modality was…

  1. Improvement of Sprint Triathlon Performance in Trained Athletes With Positive Swim Pacing. (United States)

    Wu, Sam S X; Peiffer, Jeremiah J; Peeling, Peter; Brisswalter, Jeanick; Lau, Wing Y; Nosaka, Kazunori; Abbiss, Chris R


    To investigate the effect of 3 swim-pacing profiles on subsequent performance during a sprint-distance triathlon (SDT). Nine competitive/trained male triathletes completed 5 experimental sessions including a graded running exhaustion test, a 750-m swim time trial (STT), and 3 SDTs. The swim times of the 3 SDTs were matched, but pacing was manipulated to induce positive (ie, speed gradually decreasing from 92% to 73% STT), negative (ie, speed gradually increasing from 73% to 92% STT), or even pacing (constant 82.5% STT). The remaining disciplines were completed at a self-selected maximal pace. Speed over the entire triathlon, power output during the cycle discipline, rating of perceived exertion (RPE) for each discipline, and heart rate during the cycle and run were determined. Faster cycle and overall triathlon times were achieved with positive swim pacing (30.5 ± 1.8 and 65.9 ± 4.0 min, respectively), as compared with the even (31.4 ± 1.0 min, P = .018 and 67.7 ± 3.9 min, P = .034, effect size [ES] = 0.46, respectively) and negative (31.8 ± 1.6 min, P = .011 and 67.3 ± 3.7 min, P = .041, ES = 0.36, respectively) pacing. Positive swim pacing elicited a lower RPE (9 ± 2) than negative swim pacing (11 ± 2, P = .014). No differences were observed in the other measured variables. A positive swim pacing may improve overall SDT performance and should be considered by both elite and age-group athletes during racing.

  2. An Analysis of the Pacing Strategies Adopted by Elite Cross-Country Skiers. (United States)

    Losnegard, Thomas; Kjeldsen, Kasper; Skattebo, Øyvind


    Losnegard, T, Kjeldsen, K, and Skattebo, Ø. An analysis of the pacing strategies adopted by elite cross-country skiers. J Strength Cond Res 30(11): 3256-3260, 2016-Understanding the pacing strategies used by the most successful skiers may provide insight into the most desirable pacing approach in cross-country (XC) skiing. This study examined the pacing strategies adopted by male and female XC skiers of different performance standards during 10 and 15 km races in World Cup, World Championships, and Olympic events. Analyses were performed on races involving 5 km laps in the men's 15 km (number of races = 22) and the women's 10 km (n = 14) individual start races (classic and freestyle) from season 2002/2003 to season 2013/2014. Final rank and lap times for the 40 top finishers in each race were analyzed. Both sexes demonstrated a positive pacing pattern shown by a decline in velocity from the first to the last lap (men: 6.76 ± 0.43 m·s vs. 6.47 ± 0.46 m·s; p < 0.001; women: 6.0 ± 0.47 m·s vs. 5.87 ± 0.53 m·s; p < 0.001). For the men, slower skiers (final ranking 21st-30th and 31st-40th) were characterized by a quick start relative to their average velocity, with a greater decrease during the race compared with the fastest skiers (1st-10th) (p = 0.007 and p < 0.001, respectively). For the women, no group differences in pacing strategy were found. In conclusion, this study shows that the pacing strategy indicates the standard of elite male XC skiers. Examining the pacing strategies of the best male performers suggests that lower-performing male skiers should consider a more even pacing strategy to improve their performance.

  3. Attenuation of Post-Shock Increases in Brain Natriuretic Peptide with Post Shock Overdrive Pacing

    Directory of Open Access Journals (Sweden)

    Marco Budeus


    Full Text Available Background: Predischarge defibrillation threshold testing is often performed a few days after ICD implantation in order to validate defibrillation thresholds obtained at the time of implant. Ventricular fibrillation is induced with such testing and causes an increase in serum Brain Natriuretic Peptide (BNP levels. BNP is an indicator for cardiac stress. We wanted to examine the feasibility to alter the trend of BNP after predischarge testing in VVI, DDD and CRT ICD´s.Methods: We measured BNP before predischarge testing and 5, 10, 20 and 40 minutes after predischarge testing in 13 groups with each 20 patients. We evaluated patients without post shock pacing and patients with a post shock pacing frequency of 60, 70, 80, 90 and 100 bpm and a duration of 30 and 60 sec as well as a post shock pacing frequency of 80 and 90 bpm and a duration of 120 sec post shock pacing. Results: Patients without post shock pacing showed the highest BNP during the follow-up. The percentage values of BNP increased consistent significantly after 5 minutes compared with BNP before predischarge testing. The percentage values of BNP trend was significantly lower with a post shock pacing of 90 bpm and duration of 60 sec. In addition, we excluded a cardiac necrosis by predischarge testing because of similar values of myoglobin, cardiac troponin I and creatine kinase during the follow-up.Conclusions: Our results suggested that post shock pacing with 90 bpm and duration of 60 sec as the best optimized post shock pacing frequency and duration for VVI, DDD and CRT ICD´s. A reduction of cardiac stress is going to be achieved with the optimization of the post shock pacing frequency and duration.

  4. Comparison of two strategies to reduce ventricular pacing in pacemaker patients. (United States)

    Pürerfellner, Helmut; Brandt, Johan; Israel, Carsten; Sheldon, Todd; Johnson, James; Tscheliessnigg, Karlheinz; Sperzel, Johannes; Boriani, Giuseppe; Puglisi, Andrea; Milasinovic, Goran


    Managed Ventricular Pacing (MVP) and Search AV+ (SAV+) are two pacing algorithms designed to reduce ventricular pacing. MVP promotes conduction by operating in AAI/R mode with backup ventricular pacing during atrioventricular block (AVB). SAV+ operates in DDD/R mode with a nominal AV extension of 290 ms during atrial sensing and 320 ms during atrial pacing. The reduction in ventricular pacing was compared with these two algorithms in pacemaker patients. The EnRhythm and EnPulse clinical studies assessed the percentage of ventricular pacing (%VP) after 1 month. Each patient's AVB status was assigned using the following hierarchical categories: persistent third-degree AVB (p3AVB), episodic third-degree AVB (e3AVB), second-degree AVB (2AVB), first-degree AVB (1AVB), and no AVB (nAVB). The%VP was tabulated for each AVB status category. Data were available from 322 patients of whom 129 received DDD(R) pacing with the MVP algorithm activated and 193 patients with DDD(R) pacing and the SAV+ function activated, each for a month period. MVP resulted in a significantly lower median%VP than SAV+ in all AVB categories except for p3AVB: nAVB (0.3 vs 2.9, P < 0.0001), 1AVB (0.9% vs 80.6%, P < 0.0001), 2AVB (37.6 vs 99.3, P< 0.002), e3AVB (1.2 vs 42.2, P = 0.02), p3AVB (98.9 vs 100, P = 1.00). MVP resulted in a greater reduction in%VP than SAV+ across all patient groups except persistent third-degree AV block. The greatest reduction in%VP was observed in patients with mildly impaired AV conduction.

  5. Earlier Right Ventricular Pacing in Cardiac Resynchronization Therapy for a Patient with Right Axis Deviation. (United States)

    Hattori, Yusuke; Ishibashi, Kohei; Noda, Takashi; Okamura, Hideo; Kanzaki, Hideaki; Anzai, Toshihisa; Yasuda, Satoshi; Kusano, Kengo


    We describe the case of a 37-year-old woman who presented with complete right bundle branch block and right axis deviation. She was admitted to our hospital due to severe heart failure and was dependent on inotropic agents. Cardiac resynchronization therapy was initiated but did not improve her condition. After the optimization of the pacing timing, we performed earlier right ventricular pacing, which led to an improvement of her heart failure. Earlier right ventricular pacing should be considered in patients with complete right bundle branch block and right axis deviation when cardiac resynchronization therapy is not effective.

  6. Earlier Right Ventricular Pacing in Cardiac Resynchronization Therapy for a Patient with Right Axis Deviation (United States)

    Hattori, Yusuke; Ishibashi, Kohei; Noda, Takashi; Okamura, Hideo; Kanzaki, Hideaki; Anzai, Toshihisa; Yasuda, Satoshi; Kusano, Kengo


    We describe the case of a 37-year-old woman who presented with complete right bundle branch block and right axis deviation. She was admitted to our hospital due to severe heart failure and was dependent on inotropic agents. Cardiac resynchronization therapy was initiated but did not improve her condition. After the optimization of the pacing timing, we performed earlier right ventricular pacing, which led to an improvement of her heart failure. Earlier right ventricular pacing should be considered in patients with complete right bundle branch block and right axis deviation when cardiac resynchronization therapy is not effective. PMID:28794367

  7. Using the Surface ECG to Identify Right Ventricular Pacing Lead Position: A Cautionary Tale. (United States)

    Kaye, Gerald C; Rowe, Matthew K; Gould, Paul A


    Chronic right ventricular (RV) apical pacing may lead to the development of heart failure in some patients. Although pacing of the RV septum has been proposed as an alternative, positioning a lead in the true septum has proven challenging. In addition to fluoroscopy at implant, it has been suggested that 12-lead surface electrocardiogram (ECG) can be used to determine septal lead position; however, studies show this may be inaccurate. We present a case where a change in the ECG QRS axis late after pacemaker insertion with an active fixation lead highlights the difficulties of ECG localization of pacing leads. © 2017 Wiley Periodicals, Inc.

  8. The Musical Emotional Bursts: A validated set of musical affect bursts to investigate auditory affective processing.

    Directory of Open Access Journals (Sweden)

    Sébastien ePaquette


    Full Text Available The Musical Emotional Bursts (MEB consist of 80 brief musical executions expressing basic emotional states (happiness, sadness and fear and neutrality. These musical bursts were designed to be the musical analogue of the Montreal Affective Voices (MAV – a set of brief non-verbal affective vocalizations portraying different basic emotions. The MEB consist of short (mean duration: 1.6 sec improvisations on a given emotion or of imitations of a given MAV stimulus, played on a violin (n:40 or a clarinet (n:40. The MEB arguably represent a primitive form of music emotional expression, just like the MAV represent a primitive form of vocal, nonlinguistic emotional expression. To create the MEB, stimuli were recorded from 10 violinists and 10 clarinetists, and then evaluated by 60 participants. Participants evaluated 240 stimuli (30 stimuli x 4 [3 emotions + neutral] x 2 instruments by performing either a forced-choice emotion categorization task, a valence rating task or an arousal rating task (20 subjects per task; 40 MAVs were also used in the same session with similar task instructions. Recognition accuracy of emotional categories expressed by the MEB (n:80 was lower than for the MAVs but still very high with an average percent correct recognition score of 80.4%. Highest recognition accuracies were obtained for happy clarinet (92.0% and fearful or sad violin (88.0% each MEB stimuli. The MEB can be used to compare the cerebral processing of emotional expressions in music and vocal communication, or used for testing affective perception in patients with communication problems.

  9. Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

    International Nuclear Information System (INIS)

    Yu, Yun-Wei


    Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

  10. A Statistical Study of Interplanetary Type II Bursts: STEREO Observations (United States)

    Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy, N.; Kruparova, O.; Szabo, A.


    Coronal mass ejections (CMEs) are the primary cause of the most severe and disruptive space weather events such as solar energetic particle (SEP) events and geomagnetic storms at Earth. Interplanetary type II bursts are generated via the plasma emission mechanism by energetic electrons accelerated at CME-driven shock waves and hence identify CMEs that potentially cause space weather impact. As CMEs propagate outward from the Sun, radio emissions are generated at progressively at lower frequencies corresponding to a decreasing ambient solar wind plasma density. We have performed a statistical study of 153 interplanetary type II bursts observed by the two STEREO spacecraft between March 2008 and August 2014. These events have been correlated with manually-identified CMEs contained in the Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) catalogue. Our results confirm that faster CMEs are more likely to produce interplanetary type II radio bursts. We have compared observed frequency drifts with white-light observations to estimate angular deviations of type II burst propagation directions from radial. We have found that interplanetary type II bursts preferably arise from CME flanks. Finally, we discuss a visibility of radio emissions in relation to the CME propagation direction.

  11. Spiking and bursting patterns of fractional-order Izhikevich model (United States)

    Teka, Wondimu W.; Upadhyay, Ranjit Kumar; Mondal, Argha


    Bursting and spiking oscillations play major roles in processing and transmitting information in the brain through cortical neurons that respond differently to the same signal. These oscillations display complex dynamics that might be produced by using neuronal models and varying many model parameters. Recent studies have shown that models with fractional order can produce several types of history-dependent neuronal activities without the adjustment of several parameters. We studied the fractional-order Izhikevich model and analyzed different kinds of oscillations that emerge from the fractional dynamics. The model produces a wide range of neuronal spike responses, including regular spiking, fast spiking, intrinsic bursting, mixed mode oscillations, regular bursting and chattering, by adjusting only the fractional order. Both the active and silent phase of the burst increase when the fractional-order model further deviates from the classical model. For smaller fractional order, the model produces memory dependent spiking activity after the pulse signal turned off. This special spiking activity and other properties of the fractional-order model are caused by the memory trace that emerges from the fractional-order dynamics and integrates all the past activities of the neuron. On the network level, the response of the neuronal network shifts from random to scale-free spiking. Our results suggest that the complex dynamics of spiking and bursting can be the result of the long-term dependence and interaction of intracellular and extracellular ionic currents.

  12. Ion burst event in the earth's dayside magnetosheath

    International Nuclear Information System (INIS)

    Paschalidis, N.P.; Krimigis, S.M.; Sibeck, D.G.; McEntire, R.W.; Zanetti, L.J.; Sarris, E.T.; Christon, S.P.


    The MEPA instrument on the AMPTE/CCE Spacecraft provided ion angular distributions as rapidly as every 6 sec for H, He, and O at energies of 10 keV to 2 MeV in the dayside magnetosheath within 8.75 R E , the CCE apogee. In this report the authors discuss a burst of energetic particles in the subsolar magnetosheath and its association with rapid changes in the local magnetic field direction in such a way that the magnetic field connected the spacecraft to the magnetopause during the enhancement. They find that magnetosheath angular distributions outside the burst peaked at 90 degree pitch angles, whereas during the burst they exhibited field aligned streaming either parallel or antiparallel to the magnetic field combined with a clear earthward gradient. The clear earthward gradients at E ≥ 10 KeV, the streaming, and the slope change in the burst-time magnetosheath spectrum at ∼10 KeV suggest magnetospheric source for the burst-time ≥ 10 KeV ions and heated solar wind for E < 10 KeV

  13. Are There Multiple Populations of Fast Radio Bursts? (United States)

    Palaniswamy, Divya; Li, Ye; Zhang, Bing


    The repeating FRB 121102 (the “repeater”) shows repetitive bursting activities and was localized in a host galaxy at z = 0.193. On the other hand, despite dozens of hours of telescope time spent on follow-up observations, no other fast radio bursts (FRBs) have been observed to repeat. Yet, it has been speculated that the repeater is the prototype of FRBs, and that other FRBs should show similar repeating patterns. Using the published data, we compare the repeater with other FRBs in the observed time interval (Δt)–flux ratio (S i /S i+1) plane. We find that whereas other FRBs occupy the upper (large S i /S i+1) and right (large Δt) regions of the plane due to the non-detections of other bursts, some of the repeater bursts fall into the lower left region of the plot (short interval and small flux ratio) excluded by the non-detection data of other FRBs. The trend also exists even if one only selects those bursts detectable by the Parkes radio telescope. If other FRBs were similar to the repeater, our simulations suggest that the probability that none of them have been detected to repeat with the current searches would be ∼(10‑4–10‑3). We suggest that the repeater is not representative of the entire FRB population, and that there is strong evidence of more than one population of FRBs.

  14. Bursts generate a non-reducible spike-pattern code

    Directory of Open Access Journals (Sweden)

    Hugo G Eyherabide


    Full Text Available On the single-neuron level, precisely timed spikes can either constitute firing-rate codes or spike-pattern codes that utilize the relative timing between consecutive spikes. There has been little experimental support for the hypothesis that such temporal patterns contribute substantially to information transmission. Using grasshopper auditory receptors as a model system, we show that correlations between spikes can be used to represent behaviorally relevant stimuli. The correlations reflect the inner structure of the spike train: a succession of burst-like patterns. We demonstrate that bursts with different spike counts encode different stimulus features, such that about 20% of the transmitted information corresponds to discriminating between different features, and the remaining 80% is used to allocate these features in time. In this spike-pattern code, the "what" and the "when" of the stimuli are encoded in the duration of each burst and the time of burst onset, respectively. Given the ubiquity of burst firing, we expect similar findings also for other neural systems.

  15. An internally consistent gamma ray burst time history phenomenology (United States)

    Cline, T. L.


    A phenomenology for gamma ray burst time histories is outlined. Order of their generally chaotic appearance is attempted, based on the speculation that any one burst event can be represented above 150 keV as a superposition of similarly shaped increases of varying intensity. The increases can generally overlap, however, confusing the picture, but a given event must at least exhibit its own limiting characteristic rise and decay times if the measurements are made with instruments having adequate temporal resolution. Most catalogued observations may be of doubtful or marginal utility to test this hypothesis, but some time histories from Helios-2, Pioneer Venus Orbiter and other instruments having one-to several-millisecond capabilities appear to provide consistency. Also, recent studies of temporally resolved Solar Maximum Mission burst energy spectra are entirely compatible with this picture. The phenomenology suggested here, if correct, may assist as an analytic tool for modelling of burst processes and possibly in the definition of burst source populations.

  16. Neisseria gonorrhoeae suppresses the oxidative burst of human polymorphonuclear leukocytes. (United States)

    Criss, Alison K; Seifert, H Steven


    Symptomatic infection with Neisseria gonorrhoeae (Gc) results in a potent polymorphonuclear leukocyte (PMN)-driven inflammatory response, but the mechanisms by which Gc withstands PMN attack are poorly defined. Here we report that Gc can suppress the PMN oxidative burst, a central component of the PMN antimicrobial arsenal. Primary human PMNs remained viable after exposure to liquid-grown, exponential-phase, opacity-associated protein (Opa)-negative Gc of strains FA1090 and MS11 but did not generate reactive oxygen species (ROS), even after bacterial opsonization. Liquid-grown FA1090 Gc expressing OpaB, an Opa protein previously correlated with PMN ROS production, elicited a minor PMN oxidative burst. PMN ROS production in response to Opa(-) and OpaB+ Gc was markedly enhanced if bacteria were agar-grown or if liquid-grown bacteria were heat-killed. Liquid-grown Opa(-) Gc inhibited the PMN oxidative burst elicited by isogenic dead bacteria, formylated peptides or Staphylococcus aureus but did not inhibit PMN ROS production by OpaB+ Gc or phorbol esters. Suppression of the oxidative burst required Gc-PMN contact and bacterial protein synthesis but not phagocytosis. These results suggest that viable Gc directly inhibits PMN signalling pathways required for induction of the oxidative burst, which may contribute to gonococcal pathogenesis during inflammatory stages of gonorrhoeal disease.

  17. The Identification of Two Different Spectral Types of Pulses in Gamma-Ray Bursts (United States)

    Pendleton, G. N. (Editor); Paciesas, W. S. (Editor); Briggs, M. S. (Editor); Preece, R. D. (Editor); Mallozzi, R. S. (Editor); Meegan, C. A. (Editor); Horack, J. M. (Editor); Fishman, G. J. (Editor); Band, D. L. (Editor); Matteson, J. L. (Editor); hide


    It is shown in this study that two different types of spectral emission are generally produced in gamma-ray bursts. A subset of bursts is identified that exhibits a marked lack of fluence above 300 keV, and these bursts are shown to have luminosities about an order of magnitude lower than bursts with significant fluence above 300 keV. The bursts lacking emission above 300 keV exhibit an effectively homogeneous intensity distribution. In addition, it is shown that both types of emission are common in many bursts, demonstrating that a single source object is capable of generating both of them. These results strongly favor a gamma-ray burst source object that produces two different types of emission with varying degrees of superposition. The impact of this behavior is strong enough that it affects the properties of the burst intensity distribution, as well as the burst spectral characteristics.


    Directory of Open Access Journals (Sweden)



    Full Text Available Optical burst switching (OBS is a circuit switching paradigm that provides very high throughput with reasonable delay. In OBS, the data burst size is not uniform and can be of any length. As the size of the data burst cannot be estimated in advance, several burst assembly techniques have been proposed. In this work, an estimation of data burst is done in advance which enable us to store the data burst. In this process, buffering of the data burst reduces average latency as well as it helps to improve the burst loss probability (BLP. Finally, the investigation indicates that the deflection routing along-with buffering of contending bursts provide an effective solution by decreasing the loss probability nearly 100 times.

  19. The development of a burst criterion for zircaloy fuel cladding under LOCA conditions

    International Nuclear Information System (INIS)

    Neitzel, H.J.; Rossinger, H.E.


    A burst criterion model, which assumes that deformation is controlled by steady-state creep, has been developed for a thin-walled cladding, in this case Zircaloy-4, subjected to a differential pressure and high temperature. The creep equation is integrated to obtain a burst time at the singularity of the strain. Once the burst time is known, the burst temperature and burst pressure can be calculated from the known temperature and pressure histories. A further relationship between burst stress and burst temperature is used to calculate the burst strain. Comparison with measured burst data shows good agreement between theory and experiment was found that, if the heating rate is constant, the burst temperature increases with decreasing stress, and that, if the stress level is constant, the burst temperature increases with increasing heating rate. It was also found that anisotropy alters the burst temperature and burst strain, and that test conditions in the α-Zr temperature range have no influence on the burst data. (auth)

  20. Long-term outcome of physiologic VDD pacing versus non-physiologic VVI pacing in dogs with high-grade atrioventricular block. (United States)

    Lichtenberger, Jonathan; Scollan, Katherine F; Bulmer, Barret J; Sisson, D David


    To compare the long-term outcome associated with physiologic VDD and non-physiologic VVI or VVIR pacing in dogs with high-grade atrioventricular block. Forty-nine paced dogs with high-grade atrioventricular block were included. Retrospective review of medical records, thoracic radiographs and echocardiograms for all dogs. Patient owners and referring veterinarians were contacted for survival times and a satisfaction questionnaire was submitted to the owners. Survival times, complication rates, resolution of clinical signs, and owner satisfaction were compared between the pacing modalities. A single lead VDD pacemaker was implanted in 19 dogs (39%) whereas 30 dogs (61%) were treated with VVI pacing. The median survival time for all dogs post-pacemaker implantation was 24.5 months. Survival time was significantly decreased in dogs that were older at the time of presentation or that presented with ventricular tachycardia or reduced left ventricular fractional shortening. Median survival times after implantation were not significantly different between pacing modalities (P = 0.29). Major complication rates were 11% within the VDD group and 20% within the VVI group and were not significantly different (P = 0.46). Minor complications were significantly higher within the VDD group than within the VVI group (47% versus 7% respectively; P dogs in the VDD group experiencing transient ventricular premature contractions in the immediate post-implantation time period. Resolution of clinical signs, owner satisfaction, and quality of life perception were considered excellent in both groups. No long-term clinical benefit of VDD over VVI pacing could be identified in the present study. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. BATSE spectroscopy catalog of bright gamma-ray bursts (United States)

    Schaefer, Bradley E.; Teegarden, Bonnard J.; Fantasia, Stephan F.; Palmer, David; Cline, Thomas L.; Matteson, James L.; Band, David L.; Ford, Lyle A.; Fishman, Gerald J.; Meegar, Charles A.


    This paper presents comprehensive results on the spectra of 30 bright gamma ray bursts (GRBs) as observed by the Spectroscopy Detectors (SDs) of the Burst And Transient Source Experiment (BATSE). The data selection was strict in including only spectra that are of high reliability for continuum shape studies. This BATSE Spectroscopy Catalog presents fluences, model fits (for five spectral models for three energy ranges), and photon spectra in a standard manner for each burst. Complete information is provided to describe the data selection and analysis procedures. The catalog results are also presented in electronic format (from the Compton Observatory Science Support Center) and CD-ROM format (AAS CD-ROM series, Vol. 2). These electronic formats also present the count spectra and detector response matrices so as to allow for independent study and fitting by researchers outside the BATSE Team. This BATSE Spectroscopy Catalog complements the catalog from BATSE Large Area Detector (LAD) data by Fishman et al. (1994).

  2. Multirods burst tests under loss-of-coolant conditions

    International Nuclear Information System (INIS)

    Kawasaki, S.; Uetsuka, H.; Furuta, T.


    In order to know the upper limit of coolant flow area restriction in a fuel assembly under loss-of-coolant accidents in LWRs, burst tests of fuel bundles were performed. Each bundle consisted of 49 rods(7x7 rods), and bursts were conducted in flowing steam. In some cases, 4 rods were replaced by control rods with guide tubes in a bundle. After the burst, the ballooning behavior of each rod and the degree of coolant flow area restriction in the bundle were measured. Ballooning behavior of rods and degree of coolant flow channel restriction in bundles with control rods were not different from those without control rods. The upper limit of coolant flow channel restriction under loss-of-coolant conditions was estimated to be about 80%. (author)

  3. Bifurcation structure of a model of bursting pancreatic cells

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Lading, B.; Yanchuk, S.


    One- and two-dimensional bifurcation studies of a prototypic model of bursting oscillations in pancreatic P-cells reveal a squid-formed area of chaotic dynamics in the parameter plane, with period-doubling bifurcations on one side of the arms and saddle-node bifurcations on the other. The transit......One- and two-dimensional bifurcation studies of a prototypic model of bursting oscillations in pancreatic P-cells reveal a squid-formed area of chaotic dynamics in the parameter plane, with period-doubling bifurcations on one side of the arms and saddle-node bifurcations on the other....... The transition from this structure to the so-called period-adding structure is found to involve a subcritical period-doubling bifurcation and the emergence of type-III intermittency. The period-adding transition itself is not smooth but consists of a saddle-node bifurcation in which (n + 1)-spike bursting...

  4. Burst mode composite photography for dynamic physics demonstrations (United States)

    Lincoln, James


    I am writing this article to raise awareness of burst mode photography as a fun and engaging way for teachers and students to experience physics demonstration activities. In the context of digital photography, "burst mode" means taking multiple photographs per second, and this is a feature that now comes standard on most digital cameras—including the iPhone. Sometimes the images are composited to imply motion from a series of still pictures. By analyzing the time between the photos, students can measure rates of velocity and acceleration of moving objects. Some of these composite photographs have already shown up in the AAPT High School Physics Photo Contest. In this article I discuss some ideas for using burst mode photography in the iPhone and provide a discussion of how to edit these photographs to create a composite image. I also compare the capabilities of the iPhone and GoPro cameras in creating these photographic composites.

  5. Superconducting cosmic string loops as sources for fast radio bursts (United States)

    Cao, Xiao-Feng; Yu, Yun-Wei


    The cusp burst radiation of superconducting cosmic string (SCS) loops is thought to be a possible origin of observed fast radio bursts with the model-predicted radiation spectrum and the redshift- and energy-dependent event rate, we fit the observational redshift and energy distributions of 21 Parkes fast radio bursts and constrain the model parameters. It is found that the model can basically be consistent with the observations, if the current on the SCS loops has a present value of ˜1016μ179 /10 esu s-1 and evolves with redshift as an empirical power law ˜(1 +z )-1.3 , where μ17=μ /1017 g cm-1 is the string tension. This current evolution may provide a clue to probe the evolution of the cosmic magnetic fields and the gathering of the SCS loops to galaxy clusters.

  6. Dosimetry characterization of the Godiva Reactor under burst conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hickman, D. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Heinrichs, D. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hudson, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wong, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ward, D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wilson, C. [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Clark, L. [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Trompier, F. [Inst. for Radiation Protection and Nuclear Safety, Fontenay-aux-Roses (France)


    A series of sixteen (16) burst irradiations were performed in May 2014, fifteen of which were part of an international collaboration to characterize the Godiva IV fast burst reactor at the National Criticality Experiments Research Center (NCERC). Godiva IV is a bare cylindrical assembly of approximately 65 kg of highly enriched uranium fuel (93.2% 235U metal alloyed with 1.5% molybdenum for strength) and is designed to perform controlled prompt critical excursions (Myers 2010, Goda 2013). Twelve of the irradiations were dedicated to neutron spectral measurements using a Bonner multiple sphere spectrometer. Three irradiations, with core temperature increases of 71.1°C, 136.9°C, and 229.9°C, were performed for generating comparative fluence data, establishing corrections for varying heights, testing linearity with burst temperature, and establishing gamma dose characteristics.

  7. The Mechanism behind Erosive Bursts in Porous Media (United States)

    Jaeger, Robin; Mendoza, Miller; Herrmann, Hans


    We implemented a new model based on the Lattice Boltzmann method to simulate erosion and deposition in suspension flows through porous media. Using this model we show that the cause of erosive bursts in filtration experiments is the re-opening of clogged pores when the pressure difference between two opposite sites of the pore surpasses a certain threshold. We perform numerical simulations and find excellent agreement to experimental results when comparing shape and size distribution of pressure loss jumps, which are the direct result of erosive bursts. Furthermore, we find that erosive bursts only occur for pressure gradient thresholds within the range of two critical values, independent on how the flow is driven. We believe that our findings provide a better understanding of sudden sand production in oil wells and breakthrough in filtration. European Research Council (ERC) Advanced Grant 319968-FlowCCS.

  8. Properties of gamma-ray burst progenitor stars. (United States)

    Kumar, Pawan; Narayan, Ramesh; Johnson, Jarrett L


    We determined some basic properties of stars that produce spectacular gamma-ray bursts at the end of their lives. We assumed that accretion of the outer portion of the stellar core by a central black hole fuels the prompt emission and that fall-back and accretion of the stellar envelope later produce the plateau in the x-ray light curve seen in some bursts. Using x-ray data for three bursts, we estimated the radius of the stellar core to be approximately (1 - 3) x 10(10) cm and that of the stellar envelope to be approximately (1 - 2) x 10(11) cm. The density profile in the envelope is fairly shallow, with rho approximately r(-2) (where rho is density and r is distance from the center of the explosion). The rotation speeds of the core and envelope are approximately 0.05 and approximately 0.2 of the local Keplerian speed, respectively.

  9. Fokker-Planck simulation study of Alfven eigenmode burst

    International Nuclear Information System (INIS)

    Todo, Y.; Watanabe, T.; Park, Hyoung-Bin; Sato, T.


    Recurrent bursts of toroidicity-induced Alfven eigenmodes (TAEs) are reproduced with a Fokker-Planck-magnetohydrodynamic simulation where a fast-ion source and slowing down are incorporated self-consistently. The bursts take place at regular time intervals and the behaviors of all the TAEs are synchronized. The fast-ion transport due to TAE activity spatially broadens the classical fast-ion distribution and significantly reduces its peak value. Only a small change of the distribution takes place with each burst, leading to loss of a small fraction of the fast ions. The system stays close to the marginal stability state established through the interplay of the fast-ion source, slowing down, and TAE activity. (author)

  10. Compton-dragged Gamma-Ray Bursts Associated with Supernovae. (United States)

    Lazzati; Ghisellini; Celotti; Rees


    It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e., the overall energetics, the peak frequency of the spectrum, and the fast variability, with an efficiency that can exceed 50%. In this scenario, there is no need for particle acceleration in relativistic collisionless shocks. Furthermore, although the Poynting flux may be important in accelerating the outflow, no magnetic field is required in the gamma-ray production. The drag also naturally limits the relativistic expansion of the fireball to Gamma less, similar104.

  11. Bifurcation structure of a model of bursting pancreatic cells

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Lading, B.; Yanchuk, S.


    . The transition from this structure to the so-called period-adding structure is found to involve a subcritical period-doubling bifurcation and the emergence of type-III intermittency. The period-adding transition itself is not smooth but consists of a saddle-node bifurcation in which (n + 1)-spike bursting...... behavior is born, slightly overlapping with a subcritical period-doubling bifurcation in which n-spike bursting behavior loses its stability.......One- and two-dimensional bifurcation studies of a prototypic model of bursting oscillations in pancreatic P-cells reveal a squid-formed area of chaotic dynamics in the parameter plane, with period-doubling bifurcations on one side of the arms and saddle-node bifurcations on the other...

  12. An Approach to Endovascular Ventricular Pacing in a Patient with Ebstein Anomaly and a Mechanical Tricuspid Valve. (United States)

    Zipse, Matthew M; Groves, Daniel W; Khanna, Amber D; Nguyen, Duy Thai


    In the presence of a mechanical tricuspid valve, endocardial right ventricular pacing is contraindicated, and permanent pacing is usually achieved via a surgically implanted epicardial lead. In a patient with Ebstein anomaly, a mechanical tricuspid valve, and complete heart block, transvenous pacing was achieved by implantation of a pace-sense lead in a coronary sinus ventricular branch. Noninvasive cardiac imaging can provide information regarding anatomic variation in patients with congenital heart disease or when there are challenges to lead placement. With careful planning and execution, endovascular pacing in patients with a mechanical tricuspid valve is feasible and can safely be performed. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Characteristics of a large sample of candidates for permanent ventricular pacing included in the Biventricular Pacing for Atrio-ventricular Block to Prevent Cardiac Desynchronization Study (BioPace). (United States)

    Funck, Reinhard C; Mueller, Hans-Helge; Lunati, Maurizio; Piorkowski, Christopher; De Roy, Luc; Paul, Vince; Wittenberg, Michael; Wuensch, David; Blanc, Jean-Jacques


    The general clinical profile of European pacemaker recipients who require predominant ventricular pacing (VP) is scarcely known. We examined the demographic and clinical characteristics of the 1808 participants (out of 1833 randomized patients) of the ongoing Biventricular Pacing for Atrio-ventricular Block to Prevent Cardiac Desynchronization (BioPace) study. BioPace recruited patients between May 2003 and September 2007 predominantly in European medical centres. We analysed demographic data and described clinical characteristics and electrophysiological parameters prior to device implantation in 1808 enrolled patients. The mean age ± standard deviation (SD) of the 1808 patients was 73.5 ± 9.2 years, 1235 (68%) were men, 654 (36%) presented without structural heart disease, 547 (30%) had ischemic, 355 (20%) hypertensive, 146 (8%) valvular, and 102 (6%) non-ischemic dilated cardiomyopathy. Mean left ventricular ejection fraction was 55.4 ± 12.3%. The main pacing indications were (a) permanent and intermittent atrioventricular (AV) block in 973 (54%), (b) atrial fibrillation with slow ventricular rate in 313 (17%), and (c) miscellaneous bradyarrhythmias in 522 (29%) patients. Mean QRS duration was 118.5 ± 30.5 ms, left bundle branch block was present in 316 (17%), and atrial tachyarrhythmias in 426 (24%) patients. To the best of our knowledge, this sample is a representative source of description of the general profile of European pacemaker recipients who require predominant VP. Patients' characteristics included advanced age, predominantly male gender, preserved left ventricular systolic function, high-grade AV block, narrow QRS complex, and atrial tachyarrhythmias, the latter being present in nearly one-fourth of the cohort.

  14. Self-Paced Introductory Physics Course--An Eight-Year Progress Report (United States)

    Brown, G. C.; And Others


    Describes a self-paced, mastery-oriented introductory physics course offered at Cornell University which incorporates aspects of audio-tutorial instruction and the Personalized System of Instruction (PSI). (SL)

  15. Photovoltaics (PV) as an Eligible Measure in Residential PACE Programs: Benefits and Challenges (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    Coughlin, J.


    Property Assessed Clean Energy (PACE) financing is one of several new financial models broadening access to clean energy by addressing the barrier of initial capital cost. The majority of the PACE programs in the market today include PV as an eligible measure. PV appeals to homeowners as a way to reduce utility bills, self-generate sustainable power, increase energy independence and demonstrate a commitment to the environment. If substantial state incentives for PV exist, PV projects can be economic under PACE, especially when partnered with good net metering policies. At the same time, PV is expensive relative to other eligible measures with a return on investment horizon that might exceed program targets. This fact sheet reviews the benefits and potential challenges of including PV in PACE programs.

  16. Effects of Bepridil on Atrial Electrical Remodeling in Short-Term Rapid Pacing

    Directory of Open Access Journals (Sweden)

    Hiroto Tsuchiya, MD


    Conclusions: Bepridil prevented the shortening of the ERP and MAPD90 induced by rapid atrial pacing in the acute phase. The results of this study might explain the efficacy of bepridil for preventing the recurrence of paroxysmal AF.

  17. Effects of postshock atrial pacing on atrial defibrillation outcome in the isolated sheep heart

    NARCIS (Netherlands)

    Skanes, A. C.; Gray, R. A.; Zuur, C. L.; Jalife, J.


    BACKGROUND: Failed atrial defibrillation shocks are associated with organization of postshock activity and a substantial postshock electrical quiescence. We investigated the ability of a train of pacing stimuli to capture or locally entrain atrial myocardium during the quiescent period after

  18. Research and Its Implications for Secondary School Mathematics Instruction Via Self-Pacing (United States)

    Schoen, Harold L.


    Provides a summary of the findings of nearly one hundred-fifty studies dealing with self-paced instruction S(PI) mathematics programs that involved students at the secondary level with some implications for practice. (Author/RK)

  19. Synchronous intra-myocardial ventricular pacing without crossing the tricuspid valve or entering the coronary sinus

    Energy Technology Data Exchange (ETDEWEB)

    Konecny, Tomas; DeSimone, Christopher V.; Friedman, Paul A.; Bruce, Charles [Department of Medicine, Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Asirvatham, Samuel J., E-mail: [Department of Medicine, Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Department of Pediatric and Adolescent Medicine, Pediatric Cardiology, Mayo Clinic, Rochester, MN (United States)


    Ventricular pacing is most commonly performed at the right ventricular (RV) apex. This is not without risk as placement requires crossing the tricuspid valve (TV) and may cause valvular dysfunction and dyssynchronous activation of the ventricles. The fact that the tricuspid valve lies more apically than the mitral valve allows for the possibility of pacing the ventricles from the right atrium (RA) via the “atrio-ventricular septum” without crossing the TV or entering the coronary sinus (CS). In order to mitigate far field activation inherent to current pacing technology, we constructed a novel lead in which the cathode and anode are both intra-myocardial. We demonstrate safety and efficacy of this novel lead for ventricular pacing at the atrio-ventricular septum in canines, including improved synchronous activation of both ventricles, improved differentiation in ventricular versus atrial sensing, while providing reliable ventricular capture, opening novel and a potentially safer alternative to human cardiac resynchronization therapy.

  20. Spectral Trends of Solar Bursts at Sub-THz Frequencies (United States)

    Fernandes, L. O. T.; Kaufmann, P.; Correia, E.; Giménez de Castro, C. G.; Kudaka, A. S.; Marun, A.; Pereyra, P.; Raulin, J.-P.; Valio, A. B. M.


    Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 - 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 - 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena.


    Directory of Open Access Journals (Sweden)

    Bill Phillips


    Full Text Available Cardiolocomotor synchronization (CLS has been well established for individuals engaged in rhythmic activity, such as walking, running, or cycling. When frequency of the activity is at or near the heart rate, entrainment occurs. CLS has been shown in many cases to improve the efficiency of locomotor activity, improving stroke volume, reducing blood pressure variability, and lowering the oxygen uptake (VO2. Instead of a 1:1 frequency ratio of activity to heart rate, an investigation was performed to determine if different harmonic coupling at other simple integer ratios (e.g. 1:2, 2:3, 3:2 could achieve any performance benefits. CLS was ensured by pacing the stride rate according to the measured heartbeat (i.e., adaptive paced CLS, or forced CLS. An algorithm was designed that determined the simplest ratio (lowest denominator that, when multiplied by the heart rate will fall within an individualized, predetermined comfortable pacing range for the user. The algorithm was implemented on an iPhone 4, which generated a 'tick-tock' sound through the iPhone's headphones. A sham-controlled crossover study was performed with 15 volunteers of various fitness levels. Subjects ran a 3 mile (4.83 km simulated training run at their normal pace on two consecutive days (randomized one adaptive pacing, one sham. Adaptive pacing resulted in faster runs run times, with subjects running an average of 26:03 ± 3:23 for adaptive pacing and 26:38 ± 3:31 for sham (F = 5.46, p < 0.05. The increase in heart rate from the start of the race as estimated by an exponential time constant was significantly longer during adaptive pacing, τ = 0.99 ± 0.30, compared to sham, τ = 1.53 ± 0.34 (t = -6.62, p < 0.01. Eighty-seven percent of runners found it easy to adjust their stride length to match the pacing signal with seventy-nine percent reporting that pacing helped their performance. These results suggest that adaptive paced CLS may have a beneficial effect on running

  2. Tailoring device settings in cardiac resynchronization therapy using electrograms from pacing electrodes. (United States)

    Engels, Elien B; Mafi-Rad, Masih; Hermans, Ben J M; Aranda, Alfonso; van Stipdonk, Antonius M W; Rienstra, Michiel; Scheerder, Coert O S; Maass, Alexander H; Prinzen, Frits W; Vernooy, Kevin


    Left ventricular (LV) fusion pacing appears to be at least as beneficial as biventricular pacing in cardiac resynchronization therapy (CRT). Optimal LV fusion pacing critically requires adjusting the atrioventricular (AV)-delay to the delay between atrial pacing and intrinsic right ventricular (RV) activation (Ap-RV). We explored the use of electrogram (EGM)-based vectorloop (EGMV) derived from EGMs of implanted pacing leads to achieve optimal LV fusion pacing and to compare it with conventional approaches. During CRT-device implantation, 28 patients were prospectively studied. During atrial-LV pacing (Ap-LVp) at various AV-delays, LV dP/dtmax, 12-lead electrocardiogram (ECG), and unipolar EGMs were recorded. Electrocardiogram and electrogram were used to reconstruct a vectorcardiogram (VCG) and EGMV, respectively, from which the maximum QRS amplitude (QRSampl), was extracted. Ap-RV was determined: (i) conventionally as the longest AV-delay at which QRS morphology was visually unaltered during RV pacing at increasing AV-delays(Ap-RVvis; reference-method); (ii) 70% of delay between atrial pacing and RV sensing (Ap-RVaCRT); and (iii) the delay between atrial pacing and onset of QRS (Ap-QRSonset). In both the EGMV and VCG, the longest AV-delay showing an unaltered QRSampl as compared with Ap-LVp with a short AV-delay, corresponded to Ap-RVvis. In contrast, Ap-QRSonset and Ap-RVaCRT were larger. The Ap-LVp induced increase in LV dP/dtmax was larger at Ap-RVvis, Ap-RVEGMV, and Ap-RVVCG than at Ap-QRSonset (all P < 0.05) and Ap-RVaCRT (P = 0.02, P = 0.13, and P = 0.03, respectively). In this acute study, it is shown that the EGMV QRSampl can be used to determine optimal and individual CRT-device settings for LV fusion pacing, possibly improving long-term CRT response. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email:

  3. Interatrial septum versus right atrial appendage pacing for prevention of atrial fibrillation : A meta-analysis of randomized controlled trials. (United States)

    Zhang, L; Jiang, H; Wang, W; Bai, J; Liang, Y; Su, Y; Ge, J


    Interatrial septum (IAS) pacing seems to be a promising strategy for the prevention of atrial fibrillation (AF); however, studies have yielded conflicting results. This meta-analysis was to compare IAS with right atrial appendage (RAA) pacing on the prevention of postpacing AF occurrence. Pubmed, MEDLINE, EMBASE and Web of Science databases were searched through October 2016 for randomized controlled trials comparing IAS with RAA pacing on the prevention of AF. Data concerning study design, patient characteristics and outcomes were extracted. Risk ratio (RR), weighted mean differences (WMD) or standardized mean differences (SMD) were calculated using fixed or random effects models. A total of 12 trials involving 1146 patients with dual-chamber pacing were included. Although IAS was superior to RAA pacing in terms of reducing the number of AF episodes (SMD = -0.29, P = 0.05), AF burden (SMD = -0.41, P = 0.008) and P -wave duration (WMD = -34.45 ms, P IAS pacing. Nevertheless, no differences were observed concerning all-cause death (RR = 1.04, P = 0.88), procedure-related events (RR = 1.17, P = 0.69) and pacing parameters between IAS and RAA pacing in the follow-up period. IAS pacing is safe and as well tolerated as RAA pacing. Although IAS pacing may fail to prevent permanent AF occurrence and recurrences of AF, it is able to not only improve interatrial conduction, but also reduce AF burden.

  4. Effects of Fabric Parameters on Bursting Strength of Home Textiles

    Directory of Open Access Journals (Sweden)

    Ayşe Ebru TAYYAR


    Full Text Available Performances of any textile structure mostly depend on its behaviour against subjected forces in different directions. Strength tests are the most employed method in order to evaluate the performances of textile materials during usage and processing. Cloth production parameters are the most important factors that affect the fabric usage and operating performances. In this research, effects of different production parameters on bursting strength of some woven fabrics used as upholstery, drapery, and sheeting known as home textiles are investigated. It is found that fabric bursting strength is affected by fineness and density values of warp and weft yarns.

  5. Impact of Burst Buffer Architectures on Application Portability

    Energy Technology Data Exchange (ETDEWEB)

    Harms, Kevin [Argonne National Lab. (ANL), Argonne, IL (United States); Oral, H. Sarp [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Science; Atchley, Scott [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Science; Vazhkudai, Sudharshan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Science


    The Oak Ridge and Argonne Leadership Computing Facilities are both receiving new systems under the Collaboration of Oak Ridge, Argonne, and Livermore (CORAL) program. Because they are both part of the INCITE program, applications need to be portable between these two facilities. However, the Summit and Aurora systems will be vastly different architectures, including their I/O subsystems. While both systems will have POSIX-compliant parallel file systems, their Burst Buffer technologies will be different. This difference may pose challenges to application portability between facilities. Application developers need to pay attention to specific burst buffer implementations to maximize code portability.

  6. Iron inhibits respiratory burst of peritoneal phagocytes in vitro

    DEFF Research Database (Denmark)

    Gotfryd, Kamil; Jurek, Aleksandra; Kubit, Piotr


    Objective. This study examines the effects of iron ions Fe(3+) on the respiratory burst of phagocytes isolated from peritoneal effluents of continuous ambulatory peritoneal dialysis (CAPD) patients, as an in vitro model of iron overload in end-stage renal disease (ESRD). Material and Methods....... Respiratory burst of peritoneal phagocytes was measured by chemiluminescence method. Results. At the highest used concentration of iron ions Fe(3+) (100 µM), free radicals production by peritoneal phagocytes was reduced by 90% compared to control. Conclusions. Iron overload may increase the risk of infectious...

  7. A kinetic model for the burst phase of processive cellulases

    DEFF Research Database (Denmark)

    Præstgaard, Eigil; Olsen, Jens Elmerdahl; Murphy, Leigh


    Cellobiohydrolases (exocellulases) hydrolyze cellulose processively, i.e. by sequential cleaving of soluble sugars from one end of a cellulose strand. Their activity generally shows an initial burst, followed by a pronounced slowdown, even when substrate is abundant and product accumulation...... of the model, which can be solved analytically, shows that the burst and slowdown can be explained by the relative rates of the sequential reactions in the hydrolysis process and the occurrence of obstacles for the processive movement along the cellulose strand. More specifically, the maximum enzyme activity...

  8. Underestimation of pacing threshold as determined by an automatic ventricular threshold testing algorithm. (United States)

    Sauer, William H; Cooper, Joshua M; Lai, Rebecca W; Verdino, Ralph J


    In this case report, we describe markedly different pacing thresholds determined by a manual threshold test and the automatic Ventricular Capture Management algorithm. The discrepancy in pacing threshold values reported was due to the difference in the AV intervals used with the different testing methods. We propose that the differences in right ventricular dimensions with altered diastolic filling periods affected the threshold in this patient with a new passive fixation lead in the right ventricular apex.

  9. Utility of transesophageal electrocardiography to guide optimal placement of a transesophageal pacing catheter in dogs. (United States)

    Sanders, Robert A; Chapel, Emily; Garcia-Pereira, Fernando L; Venet, Katherine E


    To determine if the transesophageal atrial (A) wave amplitude or ventricular (V) wave amplitude can be used to guide optimal positioning of a transesophageal pacing catheter in dogs. Prospective clinical study. Fourteen client owned healthy dogs with a median weight of 15.4 kg (IQR = 10.6-22.4) and a median age of 12 months (IQR = 6-12). Transesophageal atrial pacing (TAP) using a 6 Fr pacing catheter was attempted in dogs under general anesthesia. The pacing catheter was inserted orally into the esophagus to a position caudal to the heart. With the pulse generator set at a rate 20 beats/minute(-1) above the intrinsic sinus rate, the catheter was slowly withdrawn until atrial pacing was noted on a surface electrocardiogram (ECG). Then the catheter was withdrawn in 1 cm increments until atrial capture was lost. Minimum pacing threshold (MPT) and transesophageal ECG were recorded at each site. Amplitudes of the A and V waves on transesophageal ECG were then measured and their relationship to MPT was evaluated. TAP was achieved in all dogs. In 9/14 dogs the site of lowest overall MPT was the same as the site of maximal A wave deflection. In dogs with at least three data points, linear regression analysis of the relationship between the estimated site of the lowest overall MPT compared to estimated site of the maximal A and V waveform amplitudes demonstrated a strong correlation (R(2) = 0.99). Transesophageal ECG A and V waveforms were correlated to MPT and could be used to direct the placement of a pacing catheter. However, the technique was technically challenging and was not considered to be clinically useful to guide the placement of a pacing catheter. © 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  10. On the pace of fertility decline in sub-Saharan Africa


    David Shapiro; Andrew Hinde


    Background: This descriptive finding examines the comparative pace of fertility decline in sub-Saharan Africa, relative to Asia, Latin America and the Caribbean, and Northern Africa.Objective: We seek to determine if fertility decline has been slower in sub-Saharan Africa than elsewhere in the developing world.Methods: United Nations 2017 estimates of national fertility are used in assessing the comparative pace of fertility decline, and the four regions are compared in terms of how far they ...

  11. Right bundle branch block pattern during right ventricular permanent pacing: Is it safe or not?


    Erdogan, Okan; Aksu, Feyza


    The present case report describes a patient with dual chamber pacemaker whose surface ECG demonstrated paced right bundle branch block pattern suggesting a malpositioned ventricular lead in the left ventricle. However, diagnostic work-up revealed that the lead was appropriately located in the right ventricular apex. Diagnostic maneuvers and clues for differentiating safe right bundle branch block pattern during permanent pacing are thoroughly revisited and discussed within the article.

  12. Ventricular defibrillation combining DC electrical field and electrical pacing: an optical mapping study (United States)

    Musunuri, Sai Shruthi; Tang, Liang; Joung, Boyoung; Berbari, Edward J.; Lin, Shien-Fong


    Although high voltage direct current (DC) shock is a standard technique to terminate ventricular fibrillation (VF), it can cause severe pain and tissue damage. The exact effect of the DC electric field, which can depolarize the heart during VF is still unknown. We hypothesized that low-energy DC field in combination with pacing (pacing+DC) could terminate VF by affecting the ventricular propagation pattern. In six Langendorff-perfused isolated rabbit hearts with the ablated sinoatrial (SA) node, the DC field was delivered to the left ventricle (cathode) and right ventricle (anode). We designed a timed protocol using LabVIEW programming that delivers pacing, DC and pacing+DC stimuli for two seconds time intervals each. The pacing pulse (with varying pacing cycle length: 300ms-30ms) was delivered to the apex. Transmembrane voltage was recorded with optical mapping technique for 16 seconds at a sampling rate of 2ms/frame. We crushed the sinoatrial node to reduce the heart rate. The baseline activation appeared to have endocardial origins with a mean escape ventricular rate of 60 +/- 5bpm at baseline. The DC field (30mA-60mA) alone increased the mean heart rate to 120+/-5bpm. Although DC alone terminated VF in a few cases, the rate of termination was very low (6.2%). However, when pacing+DC was applied, it was possible to terminate VF in 34 of 130 episodes in six rabbits. The rate of successful defibrillation of VF with pacing+DC was significantly higher than that with DC alone (20% vs 6.2%, pdefibrillation with lower energy requirements.

  13. The effect of visitor number and spice provisioning in pacing expression by jaguars evaluated through a case study

    Directory of Open Access Journals (Sweden)

    L. S. Vidal

    Full Text Available Abstract Captive animals exhibit stereotypic pacing in response to multiple causes, including the inability to escape from human contact. Environmental enrichment techniques can minimize pacing expression. By using an individual-based approach, we addressed whether the amount of time two males and a female jaguar (Panthera onca devote to pacing varied with the number of visitors and tested the effectiveness of cinnamon and black pepper in reducing pacing. The amount of time that all jaguars engaged in pacing increased significantly with the number of visitors. Despite the difference between the males regarding age and housing conditions, both devoted significantly less time to pacing following the addition of both spices, which indicates their suitability as enrichment techniques. Mean time devoted to pacing among the treatments did not differ for the female. Our findings pointed out to the validity of individual-based approaches, as they can reveal how suitable olfactory stimuli are to minimizing stereotypies irrespective of particular traits.

  14. Rate responsive pacing using cardiac resynchronization therapy in patients with chronotropic incompetence and chronic heart failure. (United States)

    Sims, Daniel B; Mignatti, Andrea; Colombo, Paolo C; Uriel, Nir; Garcia, Luis I; Ehlert, Frederick A; Jorde, Ulrich P


    Chronotropic incompetence (CI) is a common finding in patients with advanced chronic heart failure (CHF) and is associated with a worse functional capacity. Whether rate responsive pacing with cardiac resynchronization therapy (CRT) would acutely improve exercise performance in patients with advanced CHF and severe CI (heart rate) is unknown. Patients (n = 13) with CHF, a CRT device, and severe CI were randomized in a double-blind crossover pilot study to either DDD (control) or DDDR (rate responsive) pacing. Six minutes walk test (6MWT) distance, oxygen consumption at anaerobic threshold (VO(2) @ AT), and maximal oxygen consumption (VO(2) max) were measured. One week later, testing was repeated in the alternate pacing mode. Rate responsive pacing commenced with standard settings in only 9 of 13 (69%) patients. In these 9 subjects, 6MWT distance improved acutely from 358.5 ± 40.7 to 376.8 ± 24.5 m with DDDR pacing (Pheart rate at minute 3 during rate responsive pacing and improvement in VO(2) @ AT (r = 0.83, Pheart rate response may be beneficial to optimize CRT settings in this patient population.

  15. A Pilot Study on the Effects of Slow Paced Breathing on Current Food Craving. (United States)

    Meule, Adrian; Kübler, Andrea


    Heart rate variability biofeedback (HRV-BF) involves slow paced breathing (approximately six breaths per minute), thereby maximizing low-frequent heart rate oscillations and baroreflex gain. Mounting evidence suggests that HRV-BF promotes symptom reductions in a variety of physical and mental disorders. It may also positively affect eating behavior by reducing food cravings. The aim of the current study was to investigate if slow paced breathing can be useful for attenuating momentary food craving. Female students performed paced breathing either at six breaths per minute (n = 32) or at nine breaths per minute (n = 33) while watching their favorite food on the computer screen. Current food craving decreased during a first resting period, increased during paced breathing, and decreased during a second resting period in both conditions. Although current hunger increased in both conditions during paced breathing as well, it remained elevated after the second resting period in the nine breaths condition only. Thus, breathing rate did not influence specific food craving, but slow paced breathing appeared to have a delayed influence on state hunger. Future avenues are suggested for the study of HRV-BF in the context of eating behavior.

  16. The development of a burst criterion for Zircaloy fuel cladding under LOCA conditions

    International Nuclear Information System (INIS)

    Neitzel, H.J.; Rosinger, H.E.


    A burst criterion model, which assumes that deformation is controlled by steady-state creep, has been developed for a thin-walled cladding, in this case Zircaloy-4, subjected to a differential pressure and high temperature. The creep equation is integrated to obtain a burst time at the singularity of the strain. Once that urst time is known, the burst temperature and burst pressure can be calculated from the known temperature and pressure histories. A further relationship between burst stress and burst temperature is used to calculate the burst strain. Comparison with measured burst data shows good agreement between theory and experiment. It was found that, if the heating rate is constant, the burst temperature increases with decreasing stress, and that, if the stress level is constant, the burst temperature increases with increasing heating rate. It was also found that anisotropy alters the burst temperature and burst strain, and that thest conditions in the α-Zr temperature range have no influence on the burst data. (orig.) [de

  17. Obliquity-paced Pliocene West Antarctic ice sheet oscillations (United States)

    Naish, T.; Powell, R.; Levy, R.; Wilson, G.; Scherer, R.; Talarico, F.; Krissek, L.; Niessen, F.; Pompilio, M.; Wilson, T.; Carter, L.; DeConto, R.; Huybers, P.; McKay, R.; Pollard, D.; Ross, J.; Winter, D.; Barrett, P.; Browne, G.; Cody, R.; Cowan, E.; Crampton, J.; Dunbar, G.; Dunbar, N.; Florindo, F.; Gebhardt, C.; Graham, I.; Hannah, M.; Hansaraj, D.; Harwood, D.; Helling, D.; Henrys, S.; Hinnov, L.; Kuhn, G.; Kyle, P.; Laufer, A.; Maffioli, P.; Magens, D.; Mandernack, K.; McIntosh, W.; Millan, C.; Morin, R.; Ohneiser, C.; Paulsen, T.; Persico, D.; Raine, I.; Reed, J.; Riesselman, C.; Sagnotti, L.; Schmitt, D.; Sjunneskog, C.; Strong, P.; Taviani, M.; Vogel, S.; Wilch, T.; Williams, T.


    Thirty years after oxygen isotope records from microfossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth's orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the 'warmer-than-present' early-Pliocene epoch (5–3 Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming3. Here we present a marine glacial record from the upper 600 m of the AND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, 40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth's axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to 3 °C warmer than today4 and atmospheric CO2 concentration was as high as 400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model7 that simulates fluctuations in Antarctic ice volume of up to +7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity. During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt8 under conditions of elevated CO2.

  18. A New Clue in the Mystery of Fast Radio Bursts (United States)

    Kohler, Susanna


    The origin of the mysterious fast radio bursts has eluded us for more than a decade. With the help of a particularly cooperative burst, however, scientists may finally be homing in on the answer to this puzzle.A Burst RepeatsThe host of FRB 121102 is placed in context in this Gemini image. [Gemini Observatory/AURA/NSF/NRC]More than 20 fast radio bursts rare and highly energetic millisecond-duration radio pulses have been observed since the first was discovered in 2007. FRB 121102, however, is unique in its behavior: its the only one of these bursts to repeat. The many flashes observed from FRB 121102 allowed us for the first time to follow up on the burst and hunt for its location.Earlier this year, this work led to the announcement that FRB 121102s host galaxy has been identified: a dwarf galaxy located at a redshift of z = 0.193 (roughly 3 billion light-years away). Now a team of scientists led by Cees Bassa (ASTRON, the Netherlands Institute for Radio Astronomy) has performed additional follow-up to learn more about this host and what might be causing the mysterious flashes.Hubble observation of the host galaxy. The object at the bottom right is a reference star. The blue ellipse marks the extended diffuse emission of the galaxy, the red circle marks the centroid of the star-forming knot, and the white cross denotes the location of FRB 121102 ad the associated persistent radio source. [Adapted from Bassa et al. 2017]Host ObservationsBassa and collaborators used the Hubble Space Telescope, the Spitzer Space Telecsope, and the Gemini North telecsope in Hawaii to obtain optical, near-infrared, and mid-infrared observations of FRB 121102s host galaxy.The authors determined that the galaxy is a dim, irregular, low-metallicity dwarf galaxy. Its resolved, revealing a bright star-forming region roughly 4,000 light-years across in the galaxys outskirts. Intriguingly, the persistent radio source associated with FRB 121102 falls directly within that star-forming knot


    International Nuclear Information System (INIS)

    Burns, Eric; Briggs, Michael S.; Connaughton, Valerie; Zhang, Bin-Bin; Lien, Amy; Goldstein, Adam; Pelassa, Veronique; Troja, Eleonora


    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors


    Energy Technology Data Exchange (ETDEWEB)

    Burns, Eric; Briggs, Michael S. [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Connaughton, Valerie [Universities Space Research Association, Science and Technology Institute, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Lien, Amy [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Goldstein, Adam [NASA Postdoctoral Program, Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pelassa, Veronique [Smithsonian Astrophysical Observatory, P.O. Box 97, Amado, AZ 85645 (United States); Troja, Eleonora, E-mail: [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)


    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  1. Life after PACE (Program of All-Inclusive Care for the Elderly): A retrospective/prospective, qualitative analysis of the impact of closing a nurse practitioner centered PACE site. (United States)

    Meunier, Miranda J; Brant, Jeannine M; Audet, Simmy; Dickerson, Dustin; Gransbery, Karen; Ciemins, Elizabeth L


    Caring for frail older adults is a significant healthcare concern as the frailest 10% of the population account for over 70% of healthcare expenditures. Research reveals the use of comprehensive models, such as Program of All-Inclusive Care for the Elderly (PACE), leads to improved functional outcomes for participants and cost savings through decreased utilization. This study examines how closing a PACE program impacts health outcomes of previously enrolled participants. Data were collected every 6 months for 2 years via phone surveys on 34 former participants enrolled in the program at the time of the closure. The survey included questions regarding satisfaction with care, activities of daily living (ADLs), instrumental ADLs (IADLs), emergency department (ED) visits, hospitalizations, and use of home health services. Deaths and nursing home placements were monitored. Outcomes were compared during and post-PACE. Higher numbers of ED visits, hospitalizations, and nursing home placements occurred post-PACE. PACE/post-PACE differences in ADL and IADL scores were not significant, nor were death rates. Higher satisfaction existed with PACE versus non-PACE care. Comprehensive care programs such as PACE are effective in reducing healthcare utilization, thus limiting costs. Further work is required to maintain, develop, and support comprehensive models similar to PACE. ©2016 American Association of Nurse Practitioners.

  2. RXTE detects X-ray bursts from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Soleri, P.; Watts, A.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.

    After the recent report of X-ray re-brightening (ATel #2608), RXTE has observed the peculiar neutron star X-ray binary Cir X-1 eleven times during the last two weeks (May 11-25, 2010). We report the detection of nine X-ray bursts in RXTE-PCA data, 25 years after the first -and the only previous-

  3. The WATCH solar X-ray burst catalogue

    DEFF Research Database (Denmark)

    Crosby, N.; Lund, Niels; Vilmer, N.


    The WATCH experiment aboard the GRANAT satellite provides observations of the Sun in the deka-keV range covering the years 1990 through mid-1992. An introduction to the experiment is given followed by an explanation of how the WATCH solar burst catalogue was created. The different parameters list...

  4. Analysis of Burst Observations by GLAST's LAT Detector (United States)

    Band, David L.; Digel, Seth W.


    Analyzing data from GLAST's Large Area Telescope (LAT) will require sophisticated techniques. The PSF and effective area are functions of both photon energy and the position in the field-of-view. During most of the mission the observatory will survey the sky continuously and thus the LAT will detect each count from a source at a different detector orientation; each count requires its own response function! The likelihood as a function of celestial position and photon energy will be the foundation of the standard analysis techniques. However the 20 MeV-300 GeV emission at the time of the approx.100 keV burst emission (timescale of approx.10 s) can be isolated and analyzed because essentially no non-burst counts are expected within a PSF radius of the burst location during the burst. Both binned and unbinned (in energy) spectral fitting will be possible. Longer timescale afterglow emission will require the likelihood analysis that will be used for persistent sources.

  5. Effect of temperature on cone bursting, seed extraction and ...

    African Journals Online (AJOL)

    Pinus roxburghii (chir pine or long-needle pine) is considered to be a fire-hardy species. In this study the effect of a wide range of elevated temperatures (from 40 °C to 150 °C) on cone bursting and subsequent seed germination was examined in five provenances of P. roxburghii in comparison to sun drying. The maximum ...

  6. Fast Burst Synchronization for Power Line Communication Systems

    Directory of Open Access Journals (Sweden)

    Lampe Lutz


    Full Text Available Fast burst synchronization is an important requirement in asynchronous communication networks, where devices transmit short data packets in an unscheduled fashion. Such a synchronization is typically achieved by means of a preamble sent in front of the data packet. In this paper, we study fast burst synchronization for power line communication (PLC systems operating below 500 kHz and transmitting data rates of up to about 500 kbps as it is typical in various PLC network applications. In particular, we are concerned with the receiver processing of the preamble signal and the actual design of preambles suitable for fast burst synchronization in such PLC systems. Our approach is comprehensive in that it takes into account the most distinctive characteristics of the power line channel, which are multipath propagation, highly varying path loss, and disturbance by impulse noise, as well as important practical constraints, especially the need for spectral shaping of the preamble signal and fast adjustment of the automatic gain control (AGC. In fact, we regard the explicit incorporation of these various requirements into the preamble design as the main contribution of this work. We devise an optimization criterion and a stochastic algorithm to search for suitable preamble sequences. A comprehensive performance comparison of a designed and two conventional preambles shows that the designed sequence is superior in terms of (a fast burst synchronization in various transmission environments, (b fast AGC adjustment, and (c compliance of its spectrum with the spectral mask applied to the data transmit signal.

  7. Compton echoes from nearby Gamma-Ray Bursts (United States)

    Beniamini, Paz; Giannios, Dimitrios; Younes, George; van der Horst, Alexander J.; Kouveliotou, Chryssa


    The recent discovery of gravitational waves from GW170817, associated with a short Gamma-Ray Burst (GRB) at a distance of 40Mpc, has demonstrated that short GRBs can occur locally and at a reasonable rate. Furthermore, gravitational waves enable us to detect close by GRBs, even when we are observing at latitudes far from the jet's axis. We consider here Compton echoes, the scattered light from the prompt and afterglow emission. Compton echoes, an as yet undetected counterpart of GRBs, peak in X-rays and maintain a roughly constant flux for hundreds to thousands of years after the burst. Though too faint to be detected in typical cosmological GRBs, a fraction of close by bursts with a sufficiently large energy output in X-rays, and for which the surrounding medium is sufficiently dense, may indeed be observed in this way. The detection of a Compton echo could provide unique insight into the burst properties and the environment's density structure. In particular, it could potentially determine whether or not there was a successful jet that broke through the compact binary merger ejecta. We discuss here the properties and expectations from Compton echoes and suggest methods for detectability.

  8. On the Pharmacology of Oxidative Burst of Human Neutrophils

    Czech Academy of Sciences Publication Activity Database

    Nosáľ, R.; Drábiková, K.; Jančinová, V.; Mačičková, T.; Pečivová, J.; Perečko, T.; Harmatha, Juraj; Šmidrkal, J.


    Roč. 64, Suppl 4 (2015), S445-S452 ISSN 0862-8408 Institutional support: RVO:61388963 Keywords : human neutrophils * oxidative burst * chemiluminescence * protein kinase C * apoptosis Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 1.643, year: 2015

  9. Pharmacological intervention with oxidative burst in human neutrophils

    Czech Academy of Sciences Publication Activity Database

    Nosál, R.; Drábiková, K.; Jančinová, V.; Mačičková, T.; Pečivová, J.; Perečko, T.; Harmatha, Juraj


    Roč. 10, č. 2 (2017), s. 56-60 ISSN 1337-6853 Institutional support: RVO:61388963 Keywords : human neutrophils * oxidative burst * tharapeutical drugs * natural antioxidants Subject RIV: FR - Pharmacology ; Medidal Chemistry OBOR OECD: Pharmacology and pharmacy

  10. Statistical Properties of Gamma-Ray Burst Host Galaxies

    Indian Academy of Sciences (India)


    Jan 27, 2016 ... Permanent link: ... A statistical analysis of gamma-ray burst host galaxies is presented and a clear metallicity-stellar mass relation is found in our sample. A trend that a more massive host galaxy tends to have a higher star-formation rate is also found.

  11. Modulation of neutrophil oxidative burst via histamine receptors

    Czech Academy of Sciences Publication Activity Database

    Číž, Milan; Lojek, Antonín


    Roč. 170, č. 1 (2013), s. 17-22 ISSN 0007-1188 R&D Projects: GA MŠk(CZ) LD11010 Institutional support: RVO:68081707 Keywords : neutrophil * oxidative burst * reactive oxygen species Subject RIV: BO - Biophysics Impact factor: 4.990, year: 2013

  12. Subframe burst gating for Raman spectroscopy in combustion. (United States)

    Kojima, Jun; Fischer, David; Nguyen, Quang-Viet


    We describe an architecture for spontaneous Raman scattering utilizing a frame-transfer CCD sensor operating in a subframe burst-gating mode to realize time-resolved combustion diagnostics. The technique permits all-electronic optical gating with microsecond shutter speeds (noise.

  13. Pulse Phase Dependence of the Magnetar Bursts Chetana Jain ...

    Indian Academy of Sciences (India)


    the quiescent pulse profile changed from a complex multi-peaked morphology before the August 27, 1998 giant flare to a sinusoidal profile after the burst active episode. (Woods et al. 2001; Gogus et al. 2002). The pulse profile of the SGR 1806–20 became more complex after the December 27, 2004 giant flare (Palmer et al ...

  14. Search for neutrinos from Gamma-Ray Bursts with ANTARES

    NARCIS (Netherlands)

    Presani, E.


    A method to search for neutrino induced showers from gamma‐ray bursts in the ANTARES detector is presented. ANTARES consists of a three‐dimensional array of photosensitive devices that measure Cherenkov light induced by charged particles produced by high energy neutrinos interacting in the detector

  15. Swift Burst Alert Telescope Data Products and Analysis Software

    International Nuclear Information System (INIS)

    Krimm, Hans A.; Barbier, Louis M.; Barthelmy, Scott D.; Cummings, Jay R.; Gehrels, Neil; Parsons, Ann M.; Tueller, Jack; Fenimore, Edward E.; Palmer, David M.; Hullinger, Derek D.; Markwardt, Craig B.


    The Burst Alert Telescope (BAT) on the Swift gamma-ray burst mission serves as the GRB trigger for Swift as well as a sensitive imaging telescope for the energy range of 15-150 keV. All BAT data products will be available to the astronomical community along with a complete set of analysis tools. Gamma-ray burst data products include rapid discovery messages delivered immediately via the GRB Coordinates Network, and event-by-event data from which light curves and spectra of the burst are generated. During nominal operations, the instrument provides accumulated survey histograms with 5-minute time sampling and appropriate energy resolution. These survey accumulations are analyzed in a pipeline to detect new sources and derive light curves of known sources. The 5-minute surveys will also be combined to produce the BAT all sky hard X-ray survey. In addition, the instrument accumulates high time resolution light curves of the brightest BAT sources in multiple energy bands, which are merged into a source light curve database on the ground. The BAT science data products and analysis tools will be described in this paper

  16. Flavonoids inhibit the respiratory burst of neutrophils in mammals

    Czech Academy of Sciences Publication Activity Database

    Číž, Milan; Denev, P.; Kratchanova, M.; Vašíček, Ondřej; Ambrožová, Gabriela; Lojek, Antonín


    Roč. 2012, č. 2012 (2012), ID 181295 ISSN 1942-0900 R&D Projects: GA ČR(CZ) GA524/08/1753 Institutional research plan: CEZ:AV0Z50040702 Keywords : flavonoids * neutrophils * respiratory burst Subject RIV: BO - Biophysics Impact factor: 3.393, year: 2012

  17. On the extragalactic origin of gamma-ray bursts

    International Nuclear Information System (INIS)

    Johnson, M.; Teller, E.


    A theory to explain the origin of extragalactic gamma ray bursts is presented. Collisions of black dwarf and neutron stars with a subsequent fragmentation of the dwarf producing relativistic particle accelerations toward the neutron star and a resulting turbulent flow of material at the neutron star surface is postulated

  18. Optical telescope BIRT in ORIGIN for gamma ray burst observing

    DEFF Research Database (Denmark)

    Content, Robert; Content, Robert; Sharples, Ray


    The ORIGIN concept is a space mission with a gamma ray, an X-ray and an optical telescope to observe the gamma ray bursts at large Z to determine the composition and density of the intergalactic matter in the line of sight. It was an answer to the ESA M3 call for proposal. The optical telescope...

  19. Fast radio burst tied to distant dwarf galaxy (Image 2)

    National Science Foundation


    Full Text Available Radio telescope at Arecibo only localized the fast radio burst to the area inside the two circles in this image, but the Very Large Array was able to pinpoint it as a dwarf galaxy within the square (shown at intersection of cross hairs in enlarged box)

  20. On the pharmacology of oxidative burst of neutrophils

    Czech Academy of Sciences Publication Activity Database

    Nosáľ, R.; Drábiková, K.; Harmatha, Juraj; Jančinová, V.; Mačičková, T.; Pečivová, J.; Perečko, T.


    Roč. 4, č. 2 (2011), A51-A51 ISSN 1337-6853. [TOXCON 2011. Interdisciplinary Toxicology Conference /16./. 17.05.2011-20.05.2011, Praha] Institutional research plan: CEZ:AV0Z40550506 Keywords : N-feruloyl- serotonin * oxidative burst * inhibition of neutrophil activation Subject RIV: CC - Organic Chemistry

  1. The WATCH solar X-ray burst catalogue

    DEFF Research Database (Denmark)

    Crosby, N.; Lund, Niels; Vilmer, N.


    The WATCH experiment aboard the GRANAT satellite provides observations of the Sun in the deka-keV range covering the years 1990 through mid-1992. An introduction to the experiment is given followed by an explanation of how the WATCH solar burst catalogue was created. The different parameters listed...

  2. Bursts and shocks in a continuum shell model

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Bohr, Tomas; Jensen, M.H.


    We study a burst event, i.e., the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly written in characteristic form and that the right...

  3. The First Fermi-LAT Gamma-Ray Burst Catalog

    NARCIS (Netherlands)

    Ackermann, M.; et al., [Unknown; van der Horst, A.J.


    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected

  4. Statistical properties of SGR 1900+14 bursts

    NARCIS (Netherlands)

    Göğüş, E.; Woods, P.M.; Kouveliotou, C.; van Paradijs, J.; Briggs, M.S.; Duncan, R.C.; Thompson, C.


    We study the statistics of soft gamma repeater (SGR) bursts using a database of 187 events detected with BATSE and 837 events detected with the Rossi X-Ray Timing Explorer Proportional Counter Array; all events are from SGR 1900+14 during its 1998-1999 active phase. We find that the fluence or

  5. Feasibility Study Utilizing Meteor Burst Communications for Vessel Monitoring (United States)


    4. EQUIPMENT The two meteor burst systems considered are the AMBCS with its Master Station located at Anchorage and an existing mobile government owned...requirement. However, since the mobile government owned system was specifi- cally designed for flight following applications, the transi- tion to ship

  6. Focused study of thermonuclear bursts on neutron stars

    DEFF Research Database (Denmark)

    Chenevez, Jérôme


    radius expansion bursts likely eject nuclear burning ashes into the interstellar medium, and may make possible the detection of photoionization edges. Indeed, theoretical models predict that absorption edges from 58Fe at 9.2 keV, 60Zn and 62Zn at 12.2 keV should be detectable by the future missions...

  7. A search for Gamma Ray Burst Neutrinos in AMANDA

    NARCIS (Netherlands)

    Duvoort, M.R.


    To date, no neutrinos with energies in or above the GeV range have been identified from astrophysical objects. The aim of the two analyses described in this dissertation is to observe high-energy muon neutrinos from Gamma Ray Bursts (GRBs). GRBs are distant sources, which were discovered by

  8. On the burst of branched polymer melts during inflation

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Yu, Kaijia


    Two molten low-density polyethylene melts, shaped as plates, have been inflated into a circular cylinder during isothermal conditions. Lowering the inflation rates allow the plates to be inflated into a larger volume of the cylinder before bursting. Numerical simulations of the inflations have been...

  9. Which massive stars are gamma-ray burst progenitors?

    NARCIS (Netherlands)

    Petrovic, J.; Langer, N.; Yoon, S.C.; Heger, A.


    The collapsar model for gamma-ray bursts requires three essential ingredients: a massive core, removal of the hydrogen envelope, and enough angular momentum in the core. We study current massive star evolution models of solar metallicity to determine which massive star physics is capable of

  10. Massive binary systems as Gamma-ray burst progenitors

    NARCIS (Netherlands)

    Petrovic, J.


    The collapsar model for gamma-ray bursts requires three essential ingredients: a massive core, removal of the hydrogen envelope, and enough angular momentum in the core. We study current massive star evolution models of solar metallicity to determine which massive star physics is capable of

  11. Tone-burst technique measures high-intensity sound absorption (United States)

    Powell, J. G.; Van Houten, J. J.


    Tone-burst technique, in which narrow-bandwidth, short-duration sonic pulse is propagated down a standing-wave tube, measures sound absorbing capacity of materials used in jet engine noise abatement. Technique eliminates effects of tube losses and yields normal-incidence absorption coefficient of specimen.

  12. Constraints on relativity violations from gamma-ray bursts. (United States)

    Kostelecký, V Alan; Mewes, Matthew


    Tiny violations of the Lorentz symmetry of relativity and the associated discrete CPT symmetry could emerge in a consistent theory of quantum gravity such as string theory. Recent evidence for linear polarization in gamma-ray bursts improves existing sensitivities to Lorentz and CPT violation involving photons by factors ranging from ten to a million.

  13. Blood monocyte oxidative burst activity in acute P. falciparum malaria

    DEFF Research Database (Denmark)

    Nielsen, H; Theander, T G


    The release of superoxide anion from blood monocytes was studied in eight patients with acute primary attack P. falciparum malaria. Before treatment a significant enhancement of the oxidative burst prevailed, which contrasts with previous findings of a depressed monocyte chemotactic responsiveness...

  14. Relative clock verifies endogenous bursts of human dynamics (United States)

    Zhou, Tao; Zhao, Zhi-Dan; Yang, Zimo; Zhou, Changsong


    Temporal bursts are widely observed in many human-activated systems, which may result from both endogenous mechanisms like the highest-priority-first protocol and exogenous factors like the seasonality of activities. To distinguish the effects from different mechanisms is thus of theoretical significance. This letter reports a new timing method by using a relative clock, namely the time length between two consecutive events of an agent is counted as the number of other agents' events appeared during this interval. We propose a model, in which agents act either in a constant rate or with a power-law inter-event time distribution, and the global activity either keeps unchanged or varies periodically vs. time. Our analysis shows that the bursts caused by the heterogeneity of global activity can be eliminated by setting the relative clock, yet the bursts from real individual behaviors still exist. We perform extensive experiments on four large-scale systems, the search engine by AOL, a social bookmarking system —Delicious, a short-message communication network, and a microblogging system —Twitter. Seasonality of global activity is observed, yet the bursts cannot be eliminated by using the relative clock.

  15. Body shape, burst speed and escape behavior of larval anurans (United States)

    Gage H. Dayton; Daniel Saenz; Kristen A. Baum; R. Brian Langerhans; Thomas J. DeWitt


    Variation in behavior, morphology and life history traits of larval anurans across predator gradients, and consequences of that variation, have been abundantly studied. Yet the functional link between morphology and burst-swimming speed is largely unknown. We conducted experiments with two divergent species of anurans, Scaphiopus holbrookii and

  16. The LOFT perspective on neutron star thermonuclear bursts

    DEFF Research Database (Denmark)

    in ’t Zand, J.J.M.; Altamirano, D.; Ballantyne, D. R.

    This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of thermonuclear X-ray bursts on accreting neutron stars. For a summary, we refer to the paper....

  17. Pulse Phase Dependence of the Magnetar Bursts Chetana Jain ...

    Indian Academy of Sciences (India)

    σreal represents the standard deviation observed in the real dataset, while σsimulated represents the standard deviation observed in the randomly generated datasets. SGR 1900+14, the bursts are localized but are out of phase with the pulse ...

  18. Burst abdomen in pregnancy: A proposed management algorithm ...

    African Journals Online (AJOL)

    Management of the burst abdomen is complex due to the co-morbidities associated with it. When coupled with intraabdominal sepsis and pregnancy, it becomes even more difficult due to the ethical issues that have to be considered when managing both mother and child. Due to the paucity of literature on this subject, ...


    Energy Technology Data Exchange (ETDEWEB)

    Zauderer, B. A.; Berger, E.; Margutti, R.; Fong, W.; Laskar, T.; Chornock, R.; Soderberg, A. M. [Department of Astronomy, Harvard University, Cambridge, MA 02138 (United States); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Olivares E, F.; Greiner, J. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Perley, D. A.; Horesh, A.; Carpenter, J. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91225 (United States); Updike, A. C. [Department of Chemistry and Physics, Roger Williams University, Bristol, RI 02809 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Menten, K. M. [Max-Planck-Institut fuer Radioastronomie, D-53121 Bonn (Germany); Nakar, E. [Department of Astrophysics, Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Chandra, P. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Ganeshkhind, Pune 411007 (India); Castro-Tirado, A. J. [Instituto de Astrofisica de Andalucia (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Bremer, M. [Institut de Radioastronomie Millimetrique, 300 rue de la Piscine, F-38406 Saint Martin d' Heres (France); and others


    We present X-ray, optical, near-infrared (IR), and radio observations of gamma-ray bursts (GRBs) 110709B and 111215A, as well as optical and near-IR observations of their host galaxies. The combination of X-ray detections and deep optical/near-IR limits establish both bursts as ''dark''. Sub-arcsecond positions enabled by radio detections lead to robust host galaxy associations, with optical detections that indicate z {approx}< 4 (110709B) and z Almost-Equal-To 1.8-2.9 (111215A). We therefore conclude that both bursts are dark due to substantial rest-frame extinction. Using the radio and X-ray data for each burst we find that GRB 110709B requires A{sub V}{sup host}{approx}>5.3 mag and GRB 111215A requires A{sub V}{sup host}{approx}>8.5 mag (assuming z = 2). These are among the largest extinction values inferred for dark bursts to date. The two bursts also exhibit large neutral hydrogen column densities of N{sub H,{sub int}} {approx}> 10{sup 22} cm{sup -2} (z = 2) as inferred from their X-ray spectra, in agreement with the trend for dark GRBs. Moreover, the inferred values are in agreement with the Galactic A{sub V} -N{sub H} relation, unlike the bulk of the GRB population. Finally, we find that for both bursts the afterglow emission is best explained by a collimated outflow with a total beaming-corrected energy of E{sub {gamma}} + E{sub K} Almost-Equal-To (7-9) Multiplication-Sign 10{sup 51} erg (z = 2) expanding into a wind medium with a high density, M Almost-Equal-To (6-20) Multiplication-Sign 10{sup -5} M{sub Sun} yr{sup -1} (n Almost-Equal-To 100-350 cm{sup -3} at Almost-Equal-To 10{sup 17} cm). While the energy release is typical of long GRBs, the inferred density may be indicative of larger mass-loss rates for GRB progenitors in dusty (and hence metal rich) environments. This study establishes the critical role of radio observations in demonstrating the origin and properties of dark GRBs. Observations with the JVLA and ALMA will provide a

  20. The Effect of Repeating Gamma Ray Bursts on V/Vmax


    Band, David


    I consider the effect of repeating gamma ray burst sources on the statistic. I find that the treatment of repeating events, if applied consistently, will not affect the effectiveness of as a test of burst homogeneity. The calculation of for apparent repeating and nonrepeating source populations will be biased by the incorrect classification of faint bursts. The current practice of calculating using all bursts is valid and consistent.

  1. A Crazy Question: Can Apparently Brighter Gamma-ray Bursts Be Farther Away?

    Directory of Open Access Journals (Sweden)

    A. Mészáros


    Full Text Available The cosmological relationships between observed and emitted quantities are determined for gamma-ray bursts (GRBs. The relationship shows that apparently fainter bursts need not, in general, lie at larger redshifts.This is possible when the luminosities (or emitted energies in a sample of bursts increase faster than the dimming of the observed values with redshift. Four different samples of long bursts suggest that this is what really happens.

  2. Variables affecting the manifestation of and intensity of pacing behavior: A preliminary case study in zoo-housed polar bears. (United States)

    Cless, Isabelle T; Lukas, Kristen E


    High-speed video analysis was used to quantify two aspects of gait in 10 zoo-housed polar bears. These two variables were then examined as to how they differed in the conditions of pacing versus locomoting for each bear. Percent difference calculations measured the difference between pacing and locomoting data for each bear. We inferred that the higher the percent difference between pacing and locomoting in a given subject, the more intense the pacing may be. The percent difference values were analyzed alongside caregiver survey data defining the locations, frequency, and anticipatory nature of pacing in each bear, as well as each bear's age and sex, to determine whether any variables were correlated. The frequency and intensity of pacing behavior were not correlated. However, location of pacing was significantly correlated both with the subjects' age and whether or not the subject was classified as an anticipatory pacer. Bears appeared to select specific spots within their exhibits to pace, and the location therefore seemed tied to underlying motivation for the behavior. Additionally, bears that were classified in the survey as pacing anticipatorily displayed significantly more intense pacing behavior as quantified by gait analysis. © 2017 Wiley Periodicals, Inc.

  3. Relation of pace mapping QRS configuration and conduction delay to ventricular tachycardia reentry circuits in human infarct scars. (United States)

    Stevenson, W G; Sager, P T; Natterson, P D; Saxon, L A; Middlekauff, H R; Wiener, I


    This study sought to determine the relation of the paced QRS configuration and conduction delay during pace mapping to reentry circuit sites in patients with ventricular tachycardia late after myocardial infarction. The QRS configuration produced by ventricular pacing during sinus rhythm (pace mapping) can locate focal idiopathic ventricular tachycardias during catheter mapping, but postinfarction reentry circuits may be relatively large and contain regions of slow conduction. We hypothesized that for postinfarction ventricular tachycardia, 1) pacing during sinus rhythm at reentry circuit sites distant from the exit from the scar would produce a QRS configuration different from the tachycardia; and 2) a stimulus to QRS delay during pace mapping may be a useful guide to reentry circuit slow conduction zones. Catheter mapping and ablation were performed in 18 consecutive patients with ventricular tachycardia after myocardial infarction. At 85 endocardial sites in 13 patients, 12-lead electrocardiograms (ECGs) were recorded during pace mapping, and participation of each site in a reentry circuit was then evaluated by entrainment techniques during induced ventricular tachycardia or by application of radiofrequency current. Pace maps resembled tachycardia at 40 ms was observed at > or = 70% of reentry circuit sites. At many sites in postinfarction ventricular reentry circuits, the QRS configuration during pace mapping does not resemble the ventricular tachycardia QRS complex, consistent with relatively large reentry circuits or regions of functional conduction block during ventricular tachycardia. A stimulus to QRS delay during pace mapping is consistent with slow conduction and may aid in targeting endocardial sites for further evaluation during tachycardia.

  4. The oxidative burst reaction in mammalian cells depends on gravity. (United States)

    Adrian, Astrid; Schoppmann, Kathrin; Sromicki, Juri; Brungs, Sonja; von der Wiesche, Melanie; Hock, Bertold; Kolanus, Waldemar; Hemmersbach, Ruth; Ullrich, Oliver


    Gravity has been a constant force throughout the Earth's evolutionary history. Thus, one of the fundamental biological questions is if and how complex cellular and molecular functions of life on Earth require gravity. In this study, we investigated the influence of gravity on the oxidative burst reaction in macrophages, one of the key elements in innate immune response and cellular signaling. An important step is the production of superoxide by the NADPH oxidase, which is rapidly converted to H2O2 by spontaneous and enzymatic dismutation. The phagozytosis-mediated oxidative burst under altered gravity conditions was studied in NR8383 rat alveolar macrophages by means of a luminol assay. Ground-based experiments in "functional weightlessness" were performed using a 2 D clinostat combined with a photomultiplier (PMT clinostat). The same technical set-up was used during the 13th DLR and 51st ESA parabolic flight campaign. Furthermore, hypergravity conditions were provided by using the Multi-Sample Incubation Centrifuge (MuSIC) and the Short Arm Human Centrifuge (SAHC). The results demonstrate that release of reactive oxygen species (ROS) during the oxidative burst reaction depends greatly on gravity conditions. ROS release is 1.) reduced in microgravity, 2.) enhanced in hypergravity and 3.) responds rapidly and reversible to altered gravity within seconds. We substantiated the effect of altered gravity on oxidative burst reaction in two independent experimental systems, parabolic flights and 2D clinostat / centrifuge experiments. Furthermore, the results obtained in simulated microgravity (2D clinorotation experiments) were proven by experiments in real microgravity as in both cases a pronounced reduction in ROS was observed. Our experiments indicate that gravity-sensitive steps are located both in the initial activation pathways and in the final oxidative burst reaction itself, which could be explained by the role of cytoskeletal dynamics in the assembly and function

  5. Determining hydrodynamic forces in bursting bubbles using DNA nanotube mechanics (United States)

    Hariadi, Rizal F.; Winfree, Erik; Yurke, Bernard


    Quantifying the mechanical forces produced by fluid flows within the ocean is critical to understanding the ocean’s environmental phenomena. Such forces may have been instrumental in the origin of life by driving a primitive form of self-replication through fragmentation. Among the intense sources of hydrodynamic shear encountered in the ocean are breaking waves and the bursting bubbles produced by such waves. On a microscopic scale, one expects the surface-tension–driven flows produced during bubble rupture to exhibit particularly high velocity gradients due to the small size scales and masses involved. However, little work has examined the strength of shear flow rates in commonly encountered ocean conditions. By using DNA nanotubes as a novel fluid flow sensor, we investigate the elongational rates generated in bursting films within aqueous bubble foams using both laboratory buffer and ocean water. To characterize the elongational rate distribution associated with a bursting bubble, we introduce the concept of a fragmentation volume and measure its form as a function of elongational flow rate. We find that substantial volumes experience surprisingly large flow rates: during the bursting of a bubble having an air volume of 10 mm3, elongational rates at least as large as ϵ˙=1.0×108 s−1 are generated in a fragmentation volume of ∼2×10−6 μL. The determination of the elongational strain rate distribution is essential for assessing how effectively fluid motion within bursting bubbles at the ocean surface can shear microscopic particles and microorganisms, and could have driven the self-replication of a protobiont. PMID:26504222

  6. Exercise performance in young patients with complete atrioventricular block: the relevance of synchronous atrioventricular pacing. (United States)

    Gonzalez Corcia, M Cecilia; Remy, Lorraine Saint; Marchandise, Sebastien; Moniotte, Stephane


    At present, there are many pacing strategies for young patients with complete atrioventricular block. The most frequent policy is to attempt placing a dual-chamber system when possible; however, there is a group of patients that is functioning with a non-synchronous ventricular pacing, raising the question of the ideal timing to upgrade their systems. We investigated the exercise performance of a group of children and young adults with complete atrioventricular block and dual-chamber pacemakers in both single- and dual-chamber pacing modalities. A total of 15 patients performed maximal exercise stress testing after programming the VVIR or DDD modes with 2 hours of interval in a double-blind study protocol. Compared with VVIR pacing, DDD pacing resulted in increase in the peak VO2, longer test duration, major increase in the heart rate achieved during peak exercise, decreased systemic non-invasive arterial blood pressure measured at maximal exercise, higher maximal workload, prolongation of the anaerobic threshold timing, and better self-rated performance perception in all the patients. Synchronous atrioventricular pacing contributes to an increase in both the exercise performance and the performance perception in 100% of the patients. This difference contributes to create a sense of "fitness" with repercussions in the overall health, self-esteem, and life quality, as well as encourages youngster to practice sports. Our experience tends to favour upgrading patients' systems to dual-chamber systems before reaching the adolescent years, even if the centre policy is to prolong as long as possible the epicardial site in order to avoid long years of right ventricular pacing.

  7. A fast-start pacing strategy speeds pulmonary oxygen uptake kinetics and improves supramaximal running performance.

    Directory of Open Access Journals (Sweden)

    Tiago Turnes

    Full Text Available The focus of the present study was to investigate the effects of a fast-start pacing strategy on running performance and pulmonary oxygen uptake (VO2 kinetics at the upper boundary of the severe-intensity domain. Eleven active male participants (28±10 years, 70±5 kg, 176±6 cm, 57±4 mL/kg/min visited the laboratory for a series of tests that were performed until exhaustion: 1 an incremental test; 2 three laboratory test sessions performed at 95, 100 and 110% of the maximal aerobic speed; 3 two to four constant speed tests for the determination of the highest constant speed (HS that still allowed achieving maximal oxygen uptake; and 4 an exercise based on the HS using a higher initial speed followed by a subsequent decrease. To predict equalized performance values for the constant pace, the relationship between time and distance/speed through log-log modelling was used. When a fast-start was utilized, subjects were able to cover a greater distance in a performance of similar duration in comparison with a constant-pace performance (constant pace: 670 m±22%; fast-start: 683 m±22%; P = 0.029; subjects also demonstrated a higher exercise tolerance at a similar average speed when compared with constant-pace performance (constant pace: 114 s±30%; fast-start: 125 s±26%; P = 0.037. Moreover, the mean VO2 response time was reduced after a fast start (constant pace: 22.2 s±28%; fast-start: 19.3 s±29%; P = 0.025. In conclusion, middle-distance running performances with a duration of 2-3 min are improved and VO2 response time is faster when a fast-start is adopted.

  8. 76 FR 28460 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Rock Burst... (United States)


    ... DEPARTMENT OF LABOR Office of the Secretary Agency Information Collection Activities; Submission for OMB Review; Comment Request; Rock Burst Control Plan--Pertains to Underground Metal and Nonmetal... develop a rock burst plan within 90 days after a rock burst has been experienced. Stress data are normally...

  9. The puzzling thermonuclear burst behaviour of IGR J17473-2721

    DEFF Research Database (Denmark)

    We investigate the thermonuclear bursting behaviour of the X-ray transient source IGR J17473-2721, that in 2008 underwent a six month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, RXTE, and INTEGR...

  10. Left ventricular-only pacing in heart failure patients with normal atrioventricular conduction improves global function and left ventricular regional mechanics compared with biventricular pacing: an adaptive cardiac resynchronization therapy sub-study. (United States)

    Burns, Kevin V; Gage, Ryan M; Curtin, Antonia E; Gorcsan, John; Bank, Alan J


    Right ventricular (RV) pacing can impair left ventricular (LV) function. When timed with native RV activation, LV-only pacing may cause greater improvements in LV function than biventricular pacing. This study compared the chronic effects of cardiac resynchronization therapy (CRT) on LV mechanics between biventricular pacing and LV-only pacing in patients with normal atrioventricular (AV) conduction. The Adaptive CRT (aCRT) algorithm provides LV-only pacing timed with native RV activation when the AV interval is normal (≤200 ms during sinus rhythm). We studied patients from the aCRT trial with normal AV conduction at their baseline visit and compared changes in cardiac function after 12 months of treatment with conventional biventricular or mostly (≥80%) LV-only pacing. Speckle tracking echocardiography was used to assess LV myocardial strain before and after treatment. Despite similar improvements in Packer's clinical composite scores and LV volumes, LV-only paced patients (n = 70) had a greater improvement in LV ejection fraction (8.5 ± 11.3% vs. 5.5 ± 10.3%, P = 0.038) and global LV radial strain (6.3 ± 8.6% vs. 4.0 ± 10.1%, P = 0.046) than those randomized to biventricular pacing (n = 91). Strain was improved to a greater extent near the RV pacing lead, in septal and apical regions (P heart failure patients with normal AV conduction, LV-only pacing timed with native RV activation may result in greater improvements in LV ejection fraction and myocardial strain compared with biventricular pacing due to better apical and septal function. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

  11. Beyond initiation-limited translational bursting: the effects of burst size distributions on the stability of gene expression

    KAUST Repository

    Kuwahara, Hiroyuki


    A main source of gene expression noise in prokaryotes is translational bursting. It arises from efficient translation of mRNAs with low copy numbers, which makes the production of protein copies highly variable and pulsatile. To obtain analytical solutions, previous models to capture this noise source had to assume translation to be initiation-limited, representing the burst size by a specific type of a long-tail distribution. However, there is increasing evidence suggesting that the initiation is not the rate-limiting step in certain settings, for example, under stress conditions. Here, to overcome the limitations imposed by the initiation-limited assumption, we present a new analytical approach that can evaluate biological consequences of the protein burst size with a general distribution. Since our new model can capture the contribution of other factors to the translational noise, it can be used to analyze the effects of gene expression noise in more general settings. We used this new model to analytically analyze the connection between the burst size and the stability of gene expression processes in various settings. We found that the burst size with different distributions can lead to quantitatively and qualitatively different stability characteristics of protein abundance and can have non-intuitive effects. By allowing analysis of how the stability of gene expression processes changes based on various distributions of translational noise, our analytical approach is expected to enable deeper insights into the control of cell fate decision-making, the evolution of cryptic genetic variations, and fine-tuning of gene circuits.

  12. Ventricular evoked response in patients with hypertrophic obstructive cardiomyopathy treated with DDD pacing

    Directory of Open Access Journals (Sweden)

    João Ricardo M. Sant'Anna


    Full Text Available OBJECTIVE: To assess the changes in ventricular evoked responses (VER produced by the decrease in left ventricular outflow tract gradient (LVOTG in patients with hypertrophic obstructive cardiomyopathy (HOCM treated with dual-chamber (DDD pacing. METHODS: A pulse generator Physios CTM (Biotronik, Germany was implanted in 9 patients with severe drug-refractory HOCM. After implantation, the following conditions were assessed: 1 Baseline evaluation: different AV delay (ranging from 150ms to 50 ms were sequentially programmed during 5 to 10 minutes, and the LVOTG (as determined by Doppler echocardiography and VER recorded; 2 standard evaluation, when the best AV delay (resulting in the lowest LVOTG programmed at the initial evaluation was maintained so that its effect on VER and LVOTG could be assessed during each chronic pacing evaluation. RESULTS: LVOTG decreased after DDD pacing, with a mean value of 59 ± 24 mmHg after dual chamber pacemaker, which was significantly less than the gradient before pacing (98 + 22mmHg. An AV delay >100ms produced a significantly lower decrease in VER depolarization duration (VER DD when compared to an AV delay <=100ms. Linear regression analyses showed a significant correlation between the LVOTG values and the magnitude of VER (r=0.69; p<0.05 in the 9 studied patients. CONCLUSION: The telemetry obtained intramyocardial electrogram is a sensitive means to assess left ventricular dynamics in patients with HOCM treated with DDD pacing.

  13. Efficacy of Precordial Percussion Pacing Assessed in a Cardiac Standstill Microminipig Model. (United States)

    Wada, Takeshi; Ohara, Hiroshi; Nakamura, Yuji; Cao, Xin; Izumi-Nakaseko, Hiroko; Ando, Kentaro; Honda, Mitsuru; Yoshihara, Katsunori; Nakazato, Yuji; Lurie, Keith G; Sugiyama, Atsushi


    Potential cardiovascular benefits of precordial percussion pacing (PPP) during cardiac standstill are unknown.Methods and Results:A cardiac standstill model in amicrominipigwas created by inducing complete atrioventricular block with a catheter ablation technique (n=7). Next, the efficacy of cardiopulmonary resuscitation by standard chest compressions (S-CPR), PPP and ventricular electrical pacing in this model were analyzed in series (n=4). To assess the mechanism of PPP, a non-selective, stretch-activated channel blocker, amiloride, was administered during PPP (n=3). Peak systolic and diastolic arterial pressures during S-CPR, PPP and ventricular electrical pacing were statistically similar. However, the duration of developed arterial pressure with PPP was comparable to that with ventricular electrical pacing, and significantly greater than that with S-CPR. Amiloride decreased the induction rate of ventricular electrical activity by PPP in a dose-related manner. Each animal survived without any neurological deficit at 24, 48 h and 1 week, even with up to 2 h of continuous PPP. In amicrominipigmodel of cardiac standstill, PPP can become a novel means to significantly improve physiological outcomes after cardiac standstill or symptomatic bradyarrhythmias in the absence of cardiac pacing. Activation of the non-selective stretch-activated channels may mediate some of the mechanophysiological effects of PPP. Further study of PPP by itself and together with S-CPR is warranted using cardiac arrest models of atrioventricular block and asystole.

  14. Atrial pacing and thallium 201 scintigraphy: combined use for diagnosis of coronary artery disease

    International Nuclear Information System (INIS)

    Stratmann, H.G.; Mark, A.L.; Walter, K.E.; Fletcher, J.W.; Williams, G.A.


    To evaluate the presence of coronary artery disease (CAD), atrial pacing and thallium 201 scintigraphy were performed in 36 patients with stable angina pectoris who were unable to perform an adequate exercise stress test. All patients underwent cardiac catheterization. Nine patients had previously undergone coronary artery bypass surgery. Significant CAD (one or more lesions greater than or equal to 50%) was present in 33 patients. Atrial pacing produced ischemic ST segment depression (greater than or equal to 1 mm) in 18 (55%) patients with CAD, and angina in 20 patients (61%). As the number of vessels with CAD increased, there was no significant change in the sensitivities of pacing-induced angina or ST segment depression for detecting CAD. In the 3 patients without CAD, ST segment depression occurred in 1 patient and angina in none. Thallium 201 scintigraphy demonstrated perfusion defects in 27 (82%) patients with CAD, with fixed defects seen in 13 studies (39%) and reversible defects in 15 (45%). In the 3 patients without CAD, no perfusion defects were seen. The thallium 201 scan successfully predicted the presence of CAD in patients with single-vessel disease but usually underestimated the number of vessels involved in patients with multivessel disease. Combined sensitivity of pacing-induced ST segment depression and an abnormal thallium 201 scan finding for detecting CAD was 91%. The authors conclude that combined atrial pacing and thallium 201 scintigraphy is a useful test for detecting CAD in patients unable to perform an adequate exercise stress test

  15. Cardiac resynchronization therapy or atrio-biventricular pacing-what should it be called? (United States)

    Cleland, John G F; Nasir, Mansour; Tageldien, Ahmed


    Reduced cardiac efficiency caused by suboptimal synchronization of the heart's normal contraction might contribute to the development of or exacerbate heart failure. Conceptually and in practice cardiac dyssynchrony is complex. Recent studies have shown that atrio-biventricular pacing can improve cardiac synchrony in many patients and improve cardiac function, symptoms and exercise capacity, and reduce morbidity and mortality substantially. Randomized controlled trials, however, indicate that the severity of cardiac dyssynchrony, as conventionally measured, is a poor guide to treatment benefit and that correction of dyssynchrony accounts for only part of the benefit of atrio-biventricular pacing. Although some of the benefits of atrio-biventricular pacing might be mediated by cardiac resynchronization, much of the benefit could be mediated by mechanisms that are as yet unknown. Withholding atrio-biventricular pacing in patients who do not exhibit cardiac dyssynchrony on imaging but otherwise fulfil the entry criteria used in randomized controlled trials of this therapy could be unwise. Here, we examine the evidence that cardiac resynchronization is indeed the mechanism by which atrio-biventricular pacing exerts its effects.

  16. High Frequency ELM Pacing by Lithium Pellet Injection on DIII-D (United States)

    Bortolon, A.; Maingi, R.; Mansfield, D. K.; Nagy, A.; Roquemore, A. L.; Lunsford, R.; Jackson, G. L.; Osborne, T. H.; Parks, P. B.


    Full-shot, high-frequency pacing of edge localized modes (ELM) by lithium pellet injection has been demonstrated in DIII-D. A Lithium Granule Injector (LGI), recently installed on DIII-D to study pacing efficiency dependence on granule size and velocity, was tested in different ELMy scenarios (βN = 1.2-2.0) injecting granules of nominal diameter 0.3-0.9 mm, with injection speed 50-120 m/s and injection rates up to 500 Hz. Robust ELM pacing was documented on time windows up to 3.5 s, with triggering efficiency close to 100% obtained with 0.9 mm diameter granules, lower with smaller sizes and weakly dependent on granule velocity. Paced ELM frequencies up to 100 Hz were achieved, with a 2-5 fold increase over the natural ELM frequency and a consequent reduction of divertor peak heat flux. Overall, LGI high frequency pacing appeared to be compatible with high plasma performance, in terms of global confinement and pedestal characteristics. Work supported by the US Department of Energy under DE-AC02-09CH11466, DE-FC02-04ER54698.

  17. Effect of Psychological Intervention on Marital Satisfaction of Mothers with Slow Pace Under 5 Years Children

    Directory of Open Access Journals (Sweden)

    Mehran Soleymani


    Full Text Available Objectives: Objective of this study was investigating impact of early psychological interventions on marital satisfaction of mothers with slow pace under 5 years children. Considering variables of the research, that is, early psychological interventions and marital satisfaction, research hypotheses was as follows: "early psychological interventions affect marital satisfaction of mothers with slow pace under 5 years children" and it was examined. Methods: This research is of experimental type and pretest-posttest plan with control groups was used. Statistical population included all mothers with slow pace under 5 years children in Urmia. To this end, 40 mothers with slow pace children were selected as the sample in a non-random manner by convenience sampling. They were assigned randomly into two groups of 20 (20 test group and 20 control group, and finally psychological interventions were conducted on one of groups randomly. In order to evaluate marital satisfaction, Enrich marital satisfaction questionnaire with 47 items was used. Data were analyzed by univariate analysis of covariance. Results: findings showed that there is significant difference between two groups in posttest in overall score of marital satisfaction as well as in some elements such as conventional responses, marital satisfaction, personality issues, marital relationships, conflict resolution, leisure, parenting, family and friends, and ideological orientation and sexual relations (P<0.005, and no significant difference was observed in financial supervision and roles related to gender equality. Discusion: Psychological interventions were effective in promoting marital satisfaction in mothers with slow pace under 5 years children.

  18. Application of PACE Principles for Population Health Management of Frail Older Adults. (United States)

    Stefanacci, Richard G; Reich, Shelley; Casiano, Alex


    To determine which practices would have the most impact on reducing hospital and emergency department admissions and nursing home placement among older adults with multiple comorbid conditions, a literature search and survey were conducted to identify and prioritize comprehensive care principles as practiced in the Program of All-inclusive Care for the Elderly (PACE). PACE medical directors and members of the PACE interdisciplinary team (IDT) were surveyed to gain their insights on the most impactful practices, which were identified as: End-of-Life Management, Caregiver Support, Management of Red Flags, Medication Management, Participant and Caregiver Health Care System Literacy, and Care Coordination. In addition, this research evaluated measures that could be used to assess an organization's level of success with regard to each of the 6 PACE practices identified. The results reported in this article, found through a survey with PACE medical directors and IDT members concerning effective interventions, can be viewed as strategies to improve care for older adults, enabling them to maintain their independence in the community, avoid the expense of facility-based care, and enhance their quality of life.

  19. Deviation from goal pace, body temperature and body mass loss as predictors of road race performance. (United States)

    Adams, William M; Hosokawa, Yuri; Belval, Luke N; Huggins, Robert A; Stearns, Rebecca L; Casa, Douglas J


    The purpose of this study was to examine the relationship between pacing, gastrointestinal temperature (T GI ), and percent body mass loss (%BML) on relative race performance during a warm weather 11.3km road race. Observational study of a sample of active runners competing in the 2014 Falmouth Road Race. Participants ingested a T GI pill and donned a GPS enabled watch with heart rate monitoring capabilities prior to the start of the race. Percent off predicted pace (% OFF ) was calculated for seven segments of the race. Separate linear regression analyses were used to assess the relationship between pace, T ​GI , and %BML on relative race performance. One-way ANOVA was used to analyse post race T GI (≥40°C vs Body temperature (pre race T GI and post race T GI ) was not predictive of overall finish time (p>0.05). There was a trend in a slower pace (p=0.055) and greater % OFF (p=0.056) in runners finishing the race with a T GI >40°C. Overall, finish time was influenced by greater variations in pace during the first two miles of the race. In addition, runners who minimized fluid losses and had lower T GI were associated with meeting self-predicted goals. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  20. Changes of Sympathetic Activity in Patient with Chronic Atrial Fibrillation and Severe Congestive Heart Failure Treated with Biventricular Pacing

    Directory of Open Access Journals (Sweden)

    Kohei Matsushita, MD


    Full Text Available The patient was a 64-year-old man with chronic atrial fibrillation with bradycardia. Left ventricular ejection fraction was 34%. He was treated with biventricular pacing. Heart failure improved from NYHA class III to II. Sympathetic nerve activity (SNA. was recorded during 6 minutes of biventricular (BV, right ventricular apical (RVA. and left ventricular (LV. pacing. SNA was significantly lower during biventricular pacing (49.5 ± 4.0/min. compared with RVA (58.8 ±6:9/min, p = 0.016. and LV (63.3 ± 4.3/min, p = 0.002. pacing. BV pacing improves hemodynamics and decreases SNA compared with RVA or LV pacing.

  1. Optimal pacing for right ventricular and biventricular devices: minimizing, maximizing, and right ventricular/left ventricular site considerations. (United States)

    Gillis, Anne M


    The results from numerous clinical studies provide guidance for optimizing outcomes related to RV or biventricular pacing in the pacemaker and ICD populations. (1) Programming algorithms to minimize RV pacing is imperative in patients with dual-chamber pacemakers who have intrinsic AV conduction or intermittent AV conduction block. (2) Dual-chamber ICDs should be avoided in candidates without an indication for bradycardia pacing. (3) Alternate RV septal pacing sites may be considered at the time of pacemaker implantation. (4) Biventricular pacing may be beneficial in some patients with mild LV dysfunction. (5) LV lead placement at the site of latest LV activation is desirable. (6) Programming CRT systems to achieve biventricular/LV pacing >98.5% is important. (7) Protocols for AV and VV optimization in patients with CRT are not recommended after device implantation but may be considered for CRT nonresponders. (8) Novel algorithms to maximize the benefit of CRT are in evolution further.

  2. Throughput Estimation Method in Burst ACK Scheme for Optimizing Frame Size and Burst Frame Number Appropriate to SNR-Related Error Rate (United States)

    Ohteru, Shoko; Kishine, Keiji

    The Burst ACK scheme enhances effective throughput by reducing ACK overhead when a transmitter sends sequentially multiple data frames to a destination. IEEE 802.11e is one such example. The size of the data frame body and the number of burst data frames are important burst transmission parameters that affect throughput. The larger the burst transmission parameters are, the better the throughput under error-free conditions becomes. However, large data frame could reduce throughput under error-prone conditions caused by signal-to-noise ratio (SNR) deterioration. If the throughput can be calculated from the burst transmission parameters and error rate, the appropriate ranges of the burst transmission parameters could be narrowed down, and the necessary buffer size for storing transmit data or received data temporarily could be estimated. In this paper, we present a method that features a simple algorithm for estimating the effective throughput from the burst transmission parameters and error rate. The calculated throughput values agree well with the measured ones for actual wireless boards based on the IEEE 802.11-based original MAC protocol. We also calculate throughput values for larger values of the burst transmission parameters outside the assignable values of the wireless boards and find the appropriate values of the burst transmission parameters.

  3. The Synergy of Gamma-Ray Burst Detectors In The Glast Era (United States)

    Band, David L.


    Simultaneous observations by the large number of gamma-ray burst detectors operating in the GLAST era will provide the spectra, lightcurves and locations necessary for studying burst physics and testing the putative relations between intrinsic burst properties. The detectors' energy band and the accumulation timescale of their trigger system affect their sensitivity to hard vs. soft and long vs. short bursts. Coordination of the Swift and GLAST observing plans consistent with Swift's other science objectives could increase the rate of GLAST bursts with redshifts.

  4. The Synergy of Gamma-Ray Burst Detectors in the Glast Era

    International Nuclear Information System (INIS)

    Band, David L.


    Simultaneous observations by the large number of gamma-ray burst detectors operating in the GLAST era will provide the spectra, lightcurves and locations necessary for studying burst physics and testing the putative relations between intrinsic burst properties. The detectors' energy bands and the accumulation timescale of their trigger system affect their sensitivity to hard vs. soft and long vs. short bursts. Coordination of the Swift and GLAST observing plans consistent with Swift's other science objectives could increase the detection rate of GLAST bursts with redshifts

  5. An Appropriate Compression Pace is Important for Securing the Quality of Hands-only CPR : A manikin study


    Shimizu, Yoshitaka; Tanigawa, Koichi; Ishikawa, Masami; Ouhara, Kazuhisa; Oue, Kana; Yoshinaka, Taiga; Kurihara, Hidemi; Irifune, Masahiro


    It is important to implement good quality chest compressions for cardiopulmonary resuscitation (CPR). This manikin study examined the effects of different compression rates on chest compression depth variables using a metronome sound guide. Fifty sixth-year dentistry students participated in the study. Each participant performed CPR at 3 different compression rates, 110, 100, and 90 compressions per min (pace-110-g, pace-100-g, and pace-90-g) for 2 consecutive one-minute sets with a ten-secon...

  6. Effect of atrial pacing on phase analysis in patients with the Wolff-Parkinson-White syndrome

    International Nuclear Information System (INIS)

    Magosaki, Nobuhisa; Hiroe, Michiaki; Kasanuki, Hiroshi; Ohnishi, Satoshi; Tanaka, Etsuko; Horie, Toshinobu; Kusakabe, Kiyoko; Kondo, Mizuka; Hirosawa, Koshichiro


    Phase analysis of ECG-gated radionuclide ventriculography was performed during sinus rhythm and atrial pacing for 11 patients with the Wolff-Parkinson-White (WPW) syndrome. During sinus rhythm, phase analysis demonstrated abnormal early-emptying segments reflecting preexcitation in six of the 11 patients. In the remaining five patients, the precise site of abnormal early-emptying could not be detected. Atrial pacing increased the degree of pre-exicitation, and abnormal early-emptying segments became clear in all patients. Our study demonstrated the utility of atrial pacing in performing phase analysis for patients with the WPW syndrome. Seven patients had abnormal early-emptying segments; four of them with ECG type A, in the left ventricle, and three of them with ECG type B, in the right ventricle. These results were consistent with results of the body surface and electrophysiologic mapping. In patients with posterior septal accessory pathways, phase analysis suggested probable laterality of the accessory pathway. (author)

  7. Three-Dimensional Printing for In Vivo Visualization of His Bundle Pacing Leads. (United States)

    Bauch, Terry; Vijayaraman, Pugazhendhi; Dandamudi, Gopi; Ellenbogen, Kenneth


    Transvenous pacing leads have been implicated in tricuspid valve dysfunction, and our group has adopted routine use of His bundle pacing to mitigate this effect. Three-dimensional (3D) printing technology holds great promise for advancing medicine, but the high start-up costs can be a deterrent. Seeking confirmation of optimal lead placement relative to the tricuspid annulus, we used low-cost commercial and public domain technologies to generate 3D-printed hearts from selected patients with His bundle pacing leads. Our models successfully demonstrated that such lead placements avoided interference with the tricuspid valve apparatus in these cases. Future applications of 3D printing include facilitating research to minimize lead-valve interactions, understand complex cardiac anatomy, and plan complex surgical procedures. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Successful percutaneous retrieval of a leadless pacemaker due to an acute rise in pacing threshold

    Directory of Open Access Journals (Sweden)

    Ngai-yin Chan


    Full Text Available Leadless cardiac pacemakers (LCP have become available recently. Both its acute and long-term performance in a large population of patients remain to be tested. Subacute rise in pacing threshold has been reported as an uncommon complication. On the other hand, the retrieval technique for LCP with passive fixation mechanism has not been previously described in details. Herein we report a newly recognized complication of an acute rise in pacing threshold very soon after implantation of an LCP without radiographic dislodgement. Percutaneous retrieval of this LCP with passive fixation mechanism was successful using a novel technique with the cryoballoon steerable sheath and a snare. Keywords: Leadless pacemaker, Percutaneous retrieval, Pacing threshold, Bradycardia, Dislodgement


    Directory of Open Access Journals (Sweden)



    Full Text Available The demand for higher bandwidth is increasing day by day and this ever growing demand cannot be catered to with current electronic technology. Thus new communication technology like optical communication needs to be used. In the similar context OBS (optical burst switching is considered as next generation data transfer technology. In OBS information is transmitted in forms of optical bursts of variable lengths. However, contention among the bursts is a major problem in OBS system, and for contention resolution defection routing is mostly preferred. However, deflection routing increases delay. In this paper, it is shown that the arrival of very large bursts is rare event, and for moderate burst length the buffering of contending burst can provide very effective solution. However, in case of arrival of large bursts deflection can be used.

  10. The Spectral Evolution of Gamma-Ray Bursts (United States)

    Band, David L.


    The proposed project was a continuation of our work on the spectral evolution of gamma-ray bursts begun when the Co-I on this proposal. Lyle Ford, was my graduate student. In the proposal we discussed two projects. The first was finishing and publishing the last chapter of Professor Ford's thesis. In this research effort we looked for correlations in the energies of pairs of counts recorded by the BATSE Spectroscopy Detectors within a short time of each other. A greater correlation within a short time would indicate that the observed broadband spectrum is really composed of narrowband spectral components which last for a short time and which rapidly sum to the observed spectrum. We did not find any evidence for such narrowband emission, and are setting limits on its presence. Professor Ford is revising the last chapter of his thesis for publication with my participation. The second project was a continuation of my study of the cross-correlations between the gamma-ray burst lightcurves in different energy bands. I published a first study with this technique (1997. Ap.J., 486, 928) which showed that "hard-to-soft" spectral evolution is prevalent both within and between the bursts' intensity spikes. I proposed to continue developing this technique. However, I have been somewhat disillusioned about using this methodology quantitatively since it averages the spectral evolution on a given timescale over the entire burst. Nonetheless, I have been applying the technique to new bursts which are scientifically interesting for other reasons. Attached I include the cross-correlations for the burst GRB 990123, the burst during which ROTSE discovered an optical transient. The solid curve is the autocorrelatl'on of BATSE's channel 3 (100-300 keV), while the dashed, dot-dashed and 3 dots-dashed curves are the crosscorrelations of channel 3 with channels 1 (25-50 keV), 2 (50-100 keV), and 4 (300-2000 keV). The order of, and separation between, the curves on the positive lag side

  11. Imaging spectroscopy of solar radio burst fine structures. (United States)

    Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P


    Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

  12. Thermal Electrons in Gamma-Ray Burst Afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Ressler, Sean M.; Laskar, Tanmoy [Department of Astronomy, University of California, 501 Campbell Hall, Berkeley, CA 94720-3411 (United States)


    To date, nearly all multi-wavelength modeling of long-duration γ -ray bursts has ignored synchrotron radiation from the significant population of electrons expected to pass the shock without acceleration into a power-law distribution. We investigate the effect of including the contribution of thermal, non-accelerated electrons to synchrotron absorption and emission in the standard afterglow model, and show that these thermal electrons provide an additional source of opacity to synchrotron self-absorption, and yield an additional emission component at higher energies. The extra opacity results in an increase in the synchrotron self-absorption frequency by factors of 10–100 for fiducial parameters. The nature of the additional emission depends on the details of the thermal population, but is generally observed to yield a spectral peak in the optical brighter than radiation from the nonthermal population by similar factors a few seconds after the burst, remaining detectable at millimeter and radio frequencies several days later.


    International Nuclear Information System (INIS)

    Liang, S. L.; Li Aigen


    The quantities and wavelength dependencies of the dust extinction along the lines of sight toward 33 nearby gamma-ray bursts (GRBs) with redshifts z V derived from the Drude approach is generally larger by a factor of ∼2-5 than that inferred by assuming a SMC-type template extinction law. Consistent with previous studies, the extinction-to-gas ratio is mostly smaller than that of the MW, and does not seem to correlate with the shape of the extinction curve. It is shown that the standard silicate-graphite interstellar grain model closely reproduces the extinction curves of all 33 GRBs host galaxies. For these 33 bursts at z < 2, we find no evidence for the evolution of the dust extinction, dust sizes, and relative abundances of silicate to graphite on redshifts.

  14. A minimal model of burst-noise induced bistability.

    Directory of Open Access Journals (Sweden)

    Johannes Falk

    Full Text Available We investigate the influence of intrinsic noise on stable states of a one-dimensional dynamical system that shows in its deterministic version a saddle-node bifurcation between monostable and bistable behaviour. The system is a modified version of the Schlögl model, which is a chemical reaction system with only one type of molecule. The strength of the intrinsic noise is varied without changing the deterministic description by introducing bursts in the autocatalytic production step. We study the transitions between monostable and bistable behavior in this system by evaluating the number of maxima of the stationary probability distribution. We find that changing the size of bursts can destroy and even induce saddle-node bifurcations. This means that a bursty production of molecules can qualitatively change the dynamics of a chemical reaction system even when the deterministic description remains unchanged.

  15. Solar radio bursts and their relation of coronal magnetic structures

    International Nuclear Information System (INIS)

    Kattenberg, A.


    Following a general introduction, chapters II and III describe a model for coronal flux tubes. The model tube is a cylindrically symmetric localized force free current, that is embedded in a potential field. In both chapters the growth rates and sizes of the kink mode instability are calculated by solving the linearized equation of motion. In chapters IV and V, observations of solar Type-I radio bursts are presented and analysed. The observations were gathered with the 60-channel radio spectrograph in Dwingeloo. Chapters VI, VII, VIII, IX and X are concerned with observations of solar microwave bursts. The observations, with high time resolution (0.1 s) and high one-dimensional angular resolution (max. 4'') were made with the Westerbork Synthesis Radio Telescope. (Auth.)

  16. Low-Frequency Radio Bursts and Space Weather (United States)

    Gopalswamy, N.


    Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the solar system. Substantial progress has been made in the past two decades, because of the continuous and uniform data sets available from space-based radio and white-light instrumentation. This paper highlights some recent results obtained on IP radio phenomena. In particular, the source of type IV radio bursts, the behavior of type III storms, shock propagation in the IP medium, and the solar-cycle variation of type II radio bursts are considered. All these phenomena are closely related to solar eruptions and active region evolution. The results presented were obtained by combining data from the Wind and SOHO missions.

  17. Warning Method of Coal Bursting Failure Danger by Electromagnetic Radiation

    Directory of Open Access Journals (Sweden)

    Guang-Jian Liu


    Full Text Available Electromagnetic radiation (EMR can reflect the stress state and deformation level of coal, yet its warning indexes correlated with coal properties and roof caving is poorly understood. The laboratory observations of EMR effects of coal samples bursting failure and in situ investigations in the process of roof caving are presented in this paper. EMR peak with increasing stress is discussed when the failure of coal samples happens, which provides an explanation to EMR signals positively correlated well with the stress loaded. The linearly increasing relation is also found between EMR intensity and the uniaxial compressive strength, and EMR maximum amplitudes and pulses behave a logarithmic accretion tendency with bursting energy indexes of coal. By in situ investigations, it is well found that EMR amplitude can effectively warn coal deformation and failure based on the critical value 120 mV proposed from experiments.

  18. Bursts of star formation in computer simulations of dwarf galaxies

    International Nuclear Information System (INIS)

    Comins, N.F.


    A three-dimensional Stochastic Self-Propagating Star Formation (SSPSF) model of compact galacies is presented. Two phases of gas, active and inactive, are present, and permanent depletion of gas in the form of long lived, low mass stars and remnants occurs. Similarly, global infall of gas from a galactic halo or through galactic cannibalism is permitted. We base our parameters on the observed properties of the compact blue galaxy I Zw 36. Our results are that bursts of star formation occur much more frequently in these runs than continuous nonbursting star formation, suggesting that the blue compact galaxies are probably undergoing bursts rather than continuous, nonbursting low-level star formation activity

  19. Gamma Ray Bursts and Their Links With Supernovae and Cosmology (United States)

    Meszaros, Peter; Gehrels, Neil


    Gamma-ray bursts are the most luminous explosions in the Universe, whose origin and mechanism is the focus of intense interest. They appear connected to supernova remnants from massive stars or the merger of their remnants, and their brightness makes them temporarily detectable out to the largest distances yet explored in the Universe. After pioneering breakthroughs from space and ground experiments, their study is entering a new phase with observations from the recently launched Fermi satellite, as well as the prospect of detections or limits from large neutrino and gravitational wave detectors. The interplay between such observations and theoretical models of gamma-ray bursts is reviewed, as well as their connections to supernovae and cosmology.


    Directory of Open Access Journals (Sweden)



    Full Text Available The article discusses a concept of forecasting accident risk during longwall extraction in crump-risk conditions. In Polish mines rock burst hazard can be described as high compared to other mines around the world. It's related to increase of depth of longwall field operation, preparation works, including drilling of mine face pavements which leads to systematic deterioration of geological and mining conditions. Depletion of coal is also the reason why mines operate in high mining tremor risk conditions. Mines more and more often operate in decks, where there is large number of edges and remains of older decks. Rocks bursts still remain one of the most dangerous natural hazards and therefore are fundamental prob-lem and have the greatest impact on safety in mining industry. The proposed method for forecasting accidents and loss-es in people and goods can contribute to improvement of work organization methods and mine safety management system.