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Sample records for anti-tachyarrhythmia burst pacing

  1. Temporary pacing

    Directory of Open Access Journals (Sweden)

    L.J. Workman

    1983-09-01

    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.

  2. Self-Paced Fortran.

    Science.gov (United States)

    Burnett, James

    1979-01-01

    This paper describes the instructional format of the lecture and the self-paced methods of teaching FORTRAN at Michigan State University and compares end-of-term grades of students taking a second computer science course based on whether they took the first course in the self-paced or the traditional lecture format. (Author/BB)

  3. Pacing stress echocardiography

    OpenAIRE

    Agrusta Marco; Gligorova Suzana

    2005-01-01

    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 ...

  4. Pacing stress echocardiography

    Directory of Open Access Journals (Sweden)

    Agrusta Marco

    2005-12-01

    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

  5. PACE Status Update

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-11

    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.

  6. Atrial Fibrillation and Pacing Algorithms

    OpenAIRE

    Terranova, Paolo; Severgnini, Barbara; Valli, Paolo; Dell'Orto, Simonetta; Greco, Enrico Maria

    2006-01-01

    Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results ...

  7. Gamma bursts

    International Nuclear Information System (INIS)

    The Vela satellite series has recently detected gamma bursts in the 0.2-1.5MeV energy range. These bursts last an average of from 0.1 to 10s and have a fine time structure, with pulses lasting less than several tens of milliseconds. With simultaneous observations from different satellites it has been possible to determine the spatial origin of some of the bursts. No correlation, however, has been made with known objects. In spite of the fragmentary character of the information received to date, several theories have already been proposed to account for these phenomena

  8. Marathon pacing and elevation change

    CERN Document Server

    Elliott, J B

    2012-01-01

    An analysis of marathon pacing and elevation change is presented. It is based on an empirical observation of how the pace of elite and non-elite marathon runners change over the course of the marathon and a simple approximation of the energy cost of ascent and decent. It was observed that the pace of the runners slowed in a regular manner that could be broken up into four regions. That observation can be used to project target paces for a desired marathon finish time. However, that estimate fails to take in to account the energetic costs of elevation changes (hills) along the marathon course. Several approximations are made to give a coarse estimate of target paces for marathon run on courses with significant elevation changes, i.e. a hilly course. The 2012 Oakland Marathon course is used as and example of a hilly course and the times of 23 finishers are examined.

  9. Pneumothorax in cardiac pacing

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard;

    2012-01-01

    AIM: To identify risk factors for pneumothorax treated with a chest tube after cardiac pacing device implantation in a population-based cohort.METHODS AND RESULTS: A nationwide cohort study was performed based on data on 28 860 patients from the Danish Pacemaker Register, which included all Danish...... patients who received their first pacemaker (PM) or cardiac resynchronization device from 1997 to 2008. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals for the association between risk factors and pneumothorax treated with a chest tube. The median...... age was 77 years (25th and 75th percentile: 69-84) and 55% were male (n = 15 785). A total of 190 patients (0.66%) were treated for pneumothorax, which was more often in women [aOR 1.9 (1.4-2.6)], and in patients with age >80 years [aOR 1.4 (1.0-1.9)], a prior history of chronic obstructive pulmonary...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...

  11. Historical highlights in cardiac pacing.

    Science.gov (United States)

    Geddes, L A

    1990-01-01

    The benchmarks in cardiac pacing are identified, beginning with F. Steiner (1871), who rhythmically stimulated the chloroform-arrested hearts of 3 horses, 1 donkey, 10 dogs, 14 cats, and 8 rabbits. The chloroform-arrested heart in human subjects was paced by T. Greene in the following year (1872) in the UK. In 1882, H. Ziemssen in Germany applied cardiac pacing to a 42-year old woman who had a large defect in the anterior left chest wall subsequent to resection of an enchondroma. Intentional cardiac pacing did not occur until 1932, when A.A. Hyman in the US demonstrated that cardiac pacing could be clinically practical. Hyman made a batteryless pacemaker for delivery in induction shock stimuli (60-120/min) to the atria. His pacemaker was powered by a hand-wound, spring-driven generator which provided 6 min of pacemaking without rewinding. Closed-chest ventricular pacing was introduced in the US in 1952 by P.M. Zoll et al. Zoll (1956) also introduced closed-chest ventricular defibrillation. W.L. Weirich et al. (1958) demonstrated that direct-heart stimulation in closed-chest patients could be achieved with slender wire electrodes. S. Furman and J.B. Schwedel (1959) developed a monopolar catheter electrode for ventricular pacing in man. In the same year, W. Greatbatch and W.M. Chardack developed the implantable pacemaker. PMID:18238328

  12. Factors influencing pacing in triathlon

    Directory of Open Access Journals (Sweden)

    Wu SSX

    2014-09-01

    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

  13. 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

  14. The PACE evaluation: initial findings.

    Science.gov (United States)

    Branch, L G; Coulam, R F; Zimmerman, Y A

    1995-06-01

    As of mid-1994 there were nine replications of the On Lok model operating under dual capitation payments as sites in the Program of All-inclusive Care for the Elderly (PACE). A tenth site had begun operating under capitation, but was unable to remain viable. The present descriptive study documents the growth and development of the first seven of these sites, all that had been operating under capitation during 1992. Comparisons among these sites and with On Lok are presented in the areas of organizational structure, client characteristics, approaches to case management, service delivery options, and financing. There is considerable variability in the implementation of the PACE model. Combined Medicare and Medicaid capitation monthly payments range from $2,147 to $5,973. These seven PACE sites (excluding On Lok) served a total of 888 current clients at the end of 1992, after a cumulative 136 months of experience under capitation. The very slow enrollment rates may imply that the target clients are less enthusiastic about this model than are its architects. The client selection process may suggest niche-marketing or skimming, but not the full representation of the nursing home population in their states. Given both the slow enrollment and the niche-marketing (the benevolent term) or skimming (the pejorative term) that has occurred, caution about the long-term viability of the PACE model may be warranted. PMID:7622088

  15. Low atrial septum pacing in pacemaker patients

    NARCIS (Netherlands)

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant trea

  16. Low atrial septum pacing in pacemaker patients

    OpenAIRE

    Voogt, Willem Gijsbert de

    2006-01-01

    In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant treatment in the prevention of the arrhythmia related complications. These treatment modalities when available in pacemaker systems could come at a relative low cost as the indication for pacemaker imp...

  17. Web Tools: Keeping Learners on Pace

    Science.gov (United States)

    Kosloski, Mickey

    2016-01-01

    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…

  18. The pace of cultural evolution.

    Directory of Open Access Journals (Sweden)

    Charles Perreault

    Full Text Available Today, humans inhabit most of the world's terrestrial habitats. This observation has been explained by the fact that we possess a secondary inheritance mechanism, culture, in addition to a genetic system. Because it is assumed that cultural evolution occurs faster than biological evolution, humans can adapt to new ecosystems more rapidly than other animals. This assumption, however, has never been tested empirically. Here, I compare rates of change in human technologies to rates of change in animal morphologies. I find that rates of cultural evolution are inversely correlated with the time interval over which they are measured, which is similar to what is known for biological rates. This correlation explains why the pace of cultural evolution appears faster when measured over recent time periods, where time intervals are often shorter. Controlling for the correlation between rates and time intervals, I show that (1 cultural evolution is faster than biological evolution; (2 this effect holds true even when the generation time of species is controlled for; and (3 culture allows us to evolve over short time scales, which are normally accessible only to short-lived species, while at the same time allowing for us to enjoy the benefits of having a long life history.

  19. How Long does a Burst Burst?

    CERN Document Server

    Zhang, Bin-Bin; Murase, Kohta; Connaughton, Valerie; Briggs, Michael S

    2013-01-01

    Several gamma-ray bursts (GRBs) last much longer (~ hours) in gamma-rays than typical long GRBs (~ minutes), and recently it was proposed that these "ultra-long GRBs" may form a distinct population, probably with a different (e.g. blue supergiant) progenitor than typical GRBs. However, Swift observations have suggested that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with XRT observations to investigate GRB central engine activity duration and to check whether ultra-long GRBs are special. We define burst duration t_{burst} based on both gamma-ray and X-ray light curves rather than using gamma-ray observations only. We show that the distribution of t_{burst} peaks at ~ 320s for the entire sample, with 17.6% GRBs having t_{burst} > 10^3 s and 5.4% GRBs having t_{burst} > 10^4 s. The distribution shows a tail at the long t_{burst} end. The existence of a separate population is not ruled ou...

  20. Transferring PACE Assessments Upon Home Sale

    Energy Technology Data Exchange (ETDEWEB)

    National Renewable Energy Laboratory (NREL); Coughlin, Jason; Fuller, Merrian; Zimring, Mark

    2010-04-12

    A significant barrier to investing in renewable energy and comprehensive energy efficiency improvements to homes across the country is the initial capital cost. Property Assessed Clean Energy (PACE) financing is one of several new financial models broadening access to clean energy by addressing this upfront cost issue. Recently, the White House cited PACE programs as an important element of its 'Recovery through Retrofit' plan. The residential PACE model involves the creation of a special clean energy financing district that homeowners elect to opt into. Once opted in, the local government (usually at the city or county level) finances the upfront investment of the renewable energy installation and/or energy efficiency improvements. A special lien is attached to the property and the assessment is paid back as a line item on the property tax bill. As of April 2010, 17 states have passed legislation to allow their local governments to create PACE programs, two already have the authority to set up PACE programs, and over 10 additional states are actively developing enabling legislation. This policy brief analyzes one of the advantages of PACE, which is the transferability of the special assessment from one homeowner to the next when the home is sold. This analysis focuses on the potential for the outstanding lien to impact the sales negotiation process, rather than the legal nature of the lien transfer itself. The goal of this paper is to consider what implications a PACE lien may have on the home sales negotiation process so that it can be addressed upfront rather than risk a future backlash to PACE programs. If PACE programs do expand at a rapid rate, the chances are high that there will be other cases where prospective buyers uses PACE liens to negotiate lower home prices or require repayment of the lien as a condition of sale. As a result, PACE programs should highlight this issue as a potential risk factor for the sake of full disclosure. A good example

  1. Pollution Abatement and Control Expenditures Survey (PACE)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Pollution Abatement Costs and Expenditures (PACE) survey is the most comprehensive national source of pollution abatement costs and expenditures related to...

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

    Directory of Open Access Journals (Sweden)

    Michel Cabrera Ortega

    2015-10-01

    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.

  3. Optogenetic pacing in Drosophila melanogaster (Conference Presentation)

    Science.gov (United States)

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

    2016-03-01

    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.

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

    DEFF Research Database (Denmark)

    Andersson, Hedvig; Hansen, Marco Bo; Thorsberger, Mads; Biering-Sørensen, Tor; Nielsen, Jonas Bille; Graff, Claus; Pehrson, Steen; Svendsen, Jesper Hastrup

    2015-01-01

    sensitivity of manual ECG interpretation for pace spikes was low for atrial pacing (Reader 1: 0.62 [95% confidence interval (CI) 0.50-0.74]; Reader 2: 0.65 [95% CI 0.53-0.77]) and moderate for ventricular pacing (Reader 1: 0.88 [95% CI 0.81-0.93]; Reader 2: 0.93 [95% CI 0.87-0.97]). CONCLUSIONS: In patients...

  5. How long does a burst burst?

    International Nuclear Information System (INIS)

    Several gamma-ray bursts (GRBs) last much longer (∼hours) in γ-rays than typical long GRBs (∼minutes), and it has recently been proposed that these 'ultra-long GRBs' may form a distinct population, probably with a different (e.g., blue supergiant) progenitor than typical GRBs. However, Swift observations suggest that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with X-Ray Telescope observations to investigate GRB central engine activity duration and to determine whether ultra-long GRBs are unusual events. We define burst duration t burst based on both γ-ray and X-ray light curves rather than using γ-ray observations alone. We find that t burst can be reliably measured in 343 GRBs. Within this 'good' sample, 21.9% GRBs have t burst ≳ 103 s and 11.5% GRBs have t burst ≳ 104 s. There is an apparent bimodal distribution of t burst in this sample. However, when we consider an 'undetermined' sample (304 GRBs) with t burst possibly falling in the gap between GRB duration T 90 and the first X-ray observational time, as well as a selection effect against t burst falling into the first Swift orbital 'dead zone' due to observation constraints, the intrinsic underlying t burst distribution is consistent with being a single component distribution. We found that the existing evidence for a separate ultra-long GRB population is inconclusive, and further multi-wavelength observations are needed to draw a firmer conclusion. We also discuss the theoretical implications of our results. In particular, the central engine activity duration of GRBs is generally much longer than the γ-ray T 90 duration and it does not even correlate with T 90. It would be premature to make a direct connection between T 90 and the size of the progenitor star.

  6. 42 CFR 460.60 - PACE organizational structure.

    Science.gov (United States)

    2010-10-01

    ... planning a change in organizational structure must notify CMS and the State administering agency, in... 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...

  7. [The best of cardiac pacing in 1999].

    Science.gov (United States)

    Deharo, J C

    2000-01-01

    Since the first clinical application to man forty years ago, for the treatment of bradycardia, cardiac pacing has been the object of continuous technological innovation in parallel with those in electronics and computerisation. However, independently of these expected advances, there has been a surprising widening of the field of application of pacing into those of haemodynamics and rhythmology. The recent publication of the long-term results of the Pacing in Cardiomyopathy (PIC) study confirmed the sustained decrease of intraventricular pressure gradient, of NYHA functional stage and improved quality of life of patients with hypertrophic obstructive cardiomyopathy paced in the DDD mode. The investigators also underlined the placebo effect of the pacemaker. The decrease in risk of sudden death and the reduction in ventricular remodelling have not been demonstrated yet. More recently, biventricular pacing has been proposed for the treatment of dilated cardiomyopathy and a French study showed a long-term improvement in NYHA stage and effort capacity. Several prospective randomised trials are under way to validate this indication. Acute haemodynamic evaluations have confirmed the efficacy of biventricular stimulation but also underline the value of left ventricular pacing alone. The effects on mortality, the selection of patients and the optimal configuration of pacing remain to be defined. In the field of prevention of atrial arrhythmias, the results of the multicenter SYNBIAPACE study, investigating biatrial pacing in patients with interatrial conduction defects, only showed a tendency to an increase in the delay before recurrence of atrial fibrillation. The value of the memory functions of pacemakers and the algorithms of prevention of atrial arrhythmias are still under investigation. Haemodynamic transducers have been introduced in some recent pacemakers to assess myocardial contractility and have applications in the evaluation of different pacing modes and in the

  8. Phase-locked cluster oscillations in periodically forced integrate-and-fire-or-burst neuronal populations

    Science.gov (United States)

    Langdon, Angela J.; Breakspear, Michael; Coombes, Stephen

    2012-12-01

    The minimal integrate-and-fire-or-burst neuron model succinctly describes both tonic firing and postinhibitory rebound bursting of thalamocortical cells in the sensory relay. Networks of integrate-and-fire-or-burst (IFB) neurons with slow inhibitory synaptic interactions have been shown to support stable rhythmic states, including globally synchronous and cluster oscillations, in which network-mediated inhibition cyclically generates bursting in coherent subgroups of neurons. In this paper, we introduce a reduced IFB neuronal population model to study synchronization of inhibition-mediated oscillatory bursting states to periodic excitatory input. Using numeric methods, we demonstrate the existence and stability of 1:1 phase-locked bursting oscillations in the sinusoidally forced IFB neuronal population model. Phase locking is shown to arise when periodic excitation is sufficient to pace the onset of bursting in an IFB cluster without counteracting the inhibitory interactions necessary for burst generation. Phase-locked bursting states are thus found to destabilize when periodic excitation increases in strength or frequency. Further study of the IFB neuronal population model with pulse-like periodic excitatory input illustrates that this synchronization mechanism generalizes to a broad range of n:m phase-locked bursting states across both globally synchronous and clustered oscillatory regimes.

  9. Thermonuclear burst oscillations

    CERN Document Server

    Watts, Anna L

    2012-01-01

    Burst oscillations, a phenomenon observed in a significant fraction of Type I (thermonuclear) X-ray bursts, involve the development of highly asymmetric brightness patches in the burning surface layers of accreting neutron stars. Intrinsically interesting as nuclear phenomena, they are also important as probes of dense matter physics and the strong gravity, high magnetic field environment of the neutron star surface. Burst oscillation frequency is also used to measure stellar spin, and doubles the sample of rapidly rotating (above 10 Hz) accreting neutron stars with known spins. Although the mechanism remains mysterious, burst oscillation models must take into account thermonuclear flame spread, nuclear processes, rapid rotation, and the dynamical role of the magnetic field. This review provides a comprehensive summary of the observational properties of burst oscillations, an assessment of the status of the theoretical models that are being developed to explain them, and an overview of how they can be used to...

  10. No incremental benefit of multisite atrial pacing compared with right atrial pacing in patients with drug refractory paroxysmal atrial fibrillation

    OpenAIRE

    Levy, T; Walker, S; Rex, S; Rochelle, J; Paul, V.

    2001-01-01

    OBJECTIVE—To evaluate the incremental antifibrillatory effect of multisite atrial pacing compared with right atrial pacing in patients with drug refractory paroxysmal atrial fibrillation paced for arrhythmia prevention alone.
METHODS—In 20 of these patients (mean (SD) age 64 (8) years; 14 female, six male), a single blinded randomised crossover study was performed to investigate the incremental benefit of one month of multisite atrial pacing compared with one month of right atrial pacing. Out...

  11. Self-Paced Instruction: Hello, Education

    Science.gov (United States)

    Leuba, Richard J.; Flammer, Gordon H.

    1975-01-01

    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)

  12. GLAST's GBM Burst Trigger

    Science.gov (United States)

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

    2003-01-01

    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.

  13. Visual aided pacing in respiratory maneuvers

    Energy Technology Data Exchange (ETDEWEB)

    Rambaudi, L R [Laboratorio de Biofisica y Fisiologia ' Antonio Sadi Frumento' (Argentina); Rossi, E [Catedra de Bioingenieria II (Argentina); Mantaras, M C [Catedra de Bioingenieria II (Argentina); Perrone, M S [Laboratorio de Biofisica y Fisiologia ' Antonio Sadi Frumento' (Argentina); Siri, L Nicola [Catedra de Bioingenieria II (Argentina)

    2007-11-15

    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.

  14. Visual aided pacing in respiratory maneuvers

    International Nuclear Information System (INIS)

    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

  15. Diaphragm pacing: the state of the art.

    Science.gov (United States)

    Le Pimpec-Barthes, Francoise; Legras, Antoine; Arame, Alex; Pricopi, Ciprian; Boucherie, Jean-Claude; Badia, Alain; Panzini, Capucine Morelot

    2016-04-01

    Diaphragm pacing (DP) is an orphan surgical procedure that may be proposed in strictly selected ventilator-dependent patients to get an active diaphragm contraction. The goal is to wean from mechanical ventilation (MV) and restore permanent efficient breathing. The two validated indications, despite the lack of randomised control trials, concern patients with high-level spinal cord injuries (SCI) and central hypoventilation syndromes (CHS). To date, two different techniques exist. The first, intrathoracic diaphragm pacing (IT-DP), based on a radiofrequency method, in which the electrodes are directly placed around the phrenic nerve. The second, intraperitoneal diaphragm pacing (IP-DP) uses intradiaphragmatic electrodes implanted through laparoscopy. In both techniques, the phrenic nerves must be intact and diaphragm reconditioning is always required after implantation. No perioperative mortality has been reported and ventilator-weaning rate is about 72% to 96% in both techniques. Improvement of quality of life, by restoring a more physiological breathing, has been almost constant in patients that could be weaned. Failure or delay in recovery of effective diaphragm contractions could be due to irreversible amyotrophy or chest wall damage. Recent works have evaluated the interest of IP-DP in amyotrophic lateral sclerosis (ALS). After some short series were reported in the literature, the only multicentric randomized study including 74 ALS patients was prematurely stopped because of excessive mortality in paced patients. Then, another trial analysed the place of IP-DP in peripheral diaphragm dysfunction but, given the multiple biases, the published results cannot validate that indication. Reviewing all available literature as in our experience, shows that DP is an effective method to wean selected patients dependent on ventilator and improve their daily life. Other potential indications will have to be evaluated by randomised control trials. PMID:27195135

  16. Social marketing of a different pace

    OpenAIRE

    Kamin, Tanja

    2015-01-01

    This article examines social marketing as one of the approaches for managing social change. We place the concept of social marketing on the continuum between liberal and paternalistic approaches to social change management. Furthermore, we consider which forms of social change management in Slovenia are dominant, and in which position among them is social marketing. The presumption of the discussion is that social marketing has developed at different paces and with different acknowledgements ...

  17. Interplanetary Type IV Bursts

    CERN Document Server

    Hillaris, Alexander; Nindos, Alexander

    2016-01-01

    In this work we study the characteristics of moving type IV radio bursts which extend to the hectometric wavelengths (interplanetary type IV or type IV IP bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprised 48 Interplanetary type IV bursts observed by the Wind/WAVES in the 13.825 MHz?20 KHz frequency range. The dynamic spec tra of the RSTN, DAM, ARTEMIS-IV, CULGOORA, Hiraiso and IZMIRAN Radio-spectrographs were used to track the evolution of the events in the low corona; these were supplemented with SXR ?ux recordings from GOES and CME data from LASCO. Positional information for the coronal bursts were obtained by the Nan\\c{c}ay radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs and SXR ?ares. The majority of the events (45) were characterized as compact; their duration was on average 106 min. This type of events were, mostly, associated with M and X class ?ares (40 out of 45) and fast CMEs; 32 of these events had CME...

  18. 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

    2012-02-03

    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.

  19. Interplanetary Type IV Bursts

    Science.gov (United States)

    Hillaris, A.; Bouratzis, C.; Nindos, A.

    2016-08-01

    We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal

  20. Optimized multisite ventricular pacing in postoperative single-ventricle patients.

    Science.gov (United States)

    Havalad, Vinod; Cabreriza, Santos E; Cheung, Eva W; Aponte-Patel, Linda; Wang, Alice; Cheng, Bin; Wang, Daniel Y; Silver, Eric; Bacha, Emile A; Spotnitz, Henry M

    2014-10-01

    Ventricular dyssynchrony is associated with morbidity and mortality after palliation of a single ventricle. The authors hypothesized that resynchronization with optimized temporary multisite pacing postoperatively would be safe, feasible, and effective. Pacing was assessed in the intensive care unit within the first 24 h after surgery. Two unipolar atrial pacing leads and four bipolar ventricular pacing leads were placed at standardized sites intraoperatively. Pacing was optimized to maximize mean arterial pressure. The protocol tested 11 combinations of the 4 different ventricular lead sites, 6 atrioventricular delays (50-150 ms), and 14 intraventricular delays. Optimal pacing settings were thus determined and ultimately compared in four configurations: bipolar, unipolar, single-site atrioventricular pacing, and intrinsic rhythm. Each patient was his or her own control, and all pacing comparisons were implemented in random sequence. Single-ventricle palliation was performed for 17 children ages 0-21 years. Pacing increased mean arterial pressure (MAP) versus intrinsic rhythm, with the following configurations: bipolar multisite pacing increased MAP by 2.2 % (67.7 ± 2.4 to 69.2 ± 2.4 mmHg; p = 0.013) and unipolar multisite pacing increased MAP by 2.8 % (67.7 ± 2.4 to 69.6 ± 2.7 mmHg; p = 0.002). Atrioventricular single-site pacing increased MAP by 2.1 % (67.7 ± 2.4 to 69.1 ± 2.5 mmHg: p = 0.02, insignificant difference under Bonferroni correction). The echocardiographic fractional area change in nine patients increased significantly only with unipolar pacing (32 ± 3.1 to 36 ± 4.2 %; p = 0.02). No study-related adverse events occurred. Multisite pacing optimization is safe and feasible in the early postoperative period after single-ventricle palliation, with improvements in mean arterial pressure and fractional area shortening. Further study to evaluate clinical benefits is required. PMID:24827078

  1. A Repeating Fast Radio Burst

    CERN Document Server

    Spitler, L G; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-01-01

    Fast Radio Bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measures (i.e. integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of the fast radio bursts has led several authors to hypothesise that they originate in cataclysmic astrophysical events. Here we report the detection of ten additional bursts from the direction of FRB121102, using the 305-m Arecibo telescope. These new bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and wh...

  2. Mixed Burst Error Correcting Codes

    OpenAIRE

    Sethi, Amita

    2015-01-01

    In this paper, we construct codes which are an improvement on the previously known block wise burst error correcting codes in terms of their error correcting capabilities. Along with different bursts in different sub-blocks, the given codes also correct overlapping bursts of a given length in two consecutive sub-blocks of a code word. Such codes are called mixed burst correcting (mbc) codes.

  3. Self-Paced Multi-Task Learning

    OpenAIRE

    Li, Changsheng; Wei, Fan; Yan, Junchi; Dong, Weishan; Liu, Qingshan; Zha, Hongyuan

    2016-01-01

    In this paper, we propose a novel multi-task learning (MTL) framework, called Self-Paced Multi-Task Learning (SPMTL). Different from previous works treating all tasks and instances equally when training, SPMTL attempts to jointly learn the tasks by taking into consideration the complexities of both tasks and instances. This is inspired by the cognitive process of human brain that often learns from the easy to the hard. We construct a compact SPMTL formulation by proposing a new task-oriented ...

  4. A repeating fast radio burst

    Science.gov (United States)

    Spitler, L. G.; Scholz, P.; Hessels, J. W. T.; Bogdanov, S.; Brazier, A.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J.; Ferdman, R. D.; Freire, P. C. C.; Kaspi, V. M.; Lazarus, P.; Lynch, R.; Madsen, E. C.; McLaughlin, M. A.; Patel, C.; Ransom, S. M.; Seymour, A.; Stairs, I. H.; Stappers, B. W.; van Leeuwen, J.; Zhu, W. W.

    2016-03-01

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

  5. A repeating fast radio burst.

    Science.gov (United States)

    Spitler, L G; Scholz, P; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-03-10

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star. PMID:26934226

  6. Pacing: A Concept Analysis of a Chronic Pain Intervention

    OpenAIRE

    Jamieson-Lega, Kathryn; Berry, Robyn; Brown, Cary A.

    2013-01-01

    BACKGROUND: The intervention of pacing is regularly recommended for chronic pain patients. However, pacing is poorly defined and appears to be interpreted in varying, potentially contradictory manners within the field of chronic pain. This conceptual lack of clarity has implications for effective service delivery and for researchers’ ability to conduct rigorous study. An examination of the background literature demonstrates that while pacing is often one part of a multidisciplinary pain manag...

  7. Right Ventricular Septal Pacing: Has it come of age?

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2010-02-01

    Full Text Available Prolonged pacing from the right ventricular (RV apex has been shown to be associated with progressive left ventricular dysfunction as demonstrated by heart failure, atrial fibrillation and an increased morbidity and mortality [1-6]. This has led to an interest in alternate RV pacing sites and in particular the mid RV septum and the RV outflow tract (RVOT septum [7-11]. These sites are theoretically associated with a more physiological ventricular activation. Despite the perceived advantages of septal pacing, results to date are not confirmatory [12-18]. These studies were generally acute or extended to 6-months and the leads secured to the RVOT and thus were not necessarily septal. On review of the early work of Durrer et al in 1970 [19] the septal regions of the RVOT and mid RV are the first zones of the ventricle to depolarize, suggesting that pacing from these areas on the right side of the septum would achieve as normal a contraction pattern as possible. In contrast, the free wall of the RV is the last zone to be depolarized. When attempting to prove the physiologic and hemodynamic benefits of septal pacing, it seems illogical to choose the RVOT with a mix of both septal and free wall pacing. The potential benefits of septal pacing would possibly be negated by free wall pacing and thus it is not surprising that there has been no consistent benefit over RV apical pacing demonstrated.

  8. Enact legislation supporting residential property assessed clean energy financing (PACE)

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Devashree

    2012-11-15

    Congress should enact legislation that supports residential property assessed clean energy (PACE) programs in the nation’s states and metropolitan areas. Such legislation should require the Federal Housing Finance Agency (FHFA) to allow Fannie Mae and Freddie Mac to purchase residential mortgages with PACE assessments while at the same time providing responsible underwriting standards and a set of benchmarks for residential PACE assessments in order to minimize financial risks to mortgage holders. Congressional support of residential PACE financing will improve energy efficiency, encourage job creation, and foster economic growth in the nation’s state and metropolitan areas.

  9. Effect of atrial pacing therapy with selective pacing algorithms on paroxysmal atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    潘晓宏; 张雪华; 徐耕; 傅国胜; 单江

    2004-01-01

    @@ Atrial fibrillation (AF) is the most common cardiac arrhythmia among the elderly. Its incidence increases dramatically with increasing age and decreasing left ventricular function, peaking in subjects with overt congestive heart failure.1 Because of the unsatisfactory efficacy and possible serious side effects of clinically available anti-AF drugs for AF patients with sick sinus syndrome, pacing techniques have recently been applied in the treatment of AF. The cardiac pacemaker Vitatron Selection 900E has special AF diagnostic and prophylactic therapy algorithms. The objective of this study was to use the diagnostic information concerning the onset mechanisms of AF to program the preventive pacing algorithms for each patient individually and to find out whether a reduction in AF burden could be achieved.

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

    CERN Multimedia

    Aspel, Paul

    2003-01-01

    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.

  11. Social Interaction in Self-Paced Distance Education

    Science.gov (United States)

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

    2015-01-01

    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…

  12. Temporary emergency pacing-an orphan in district hospitals

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...

  13. Introduction to Optical Burst Switching

    OpenAIRE

    KERNÁCS János; SZILÁGYI Szabolcs

    2010-01-01

    Optical Burst Switching (OBS) isconsidered a popular switching paradigm for therealization of all-optical networks due to the balance itoffers between the coarse-grained Optical CircuitSwitching (OSC) and fine-grained Optical PacketSwitching (OPS). Given that the data are switched allopticallyat the burst level, Optical Burst Switchingcombines the transparency of Optical CircuitSwitching with the benefits of statistical multiplexingin Optical Packet Switching.

  14. The KN-3000 particle accelerator control expert system (PACES)

    International Nuclear Information System (INIS)

    The particle accelerator control expert system (PACES) is a computer-based operator aid, retrofitted to a model KN-3000 Van de Graaff accelerator, that is used during the start-up, steady state and shut-down phases of the accelerator. Using PACES, the operator can control the accelerator through a graphical control panel, or call upon an expert system to perform automatic start-up or shut-down. PACES then automatically stabilizes and optimizes particle beam parameters. PACES is also able to detect, diagnose and respond to operating faults, such as high-voltage sparks, vacuum system failure or loss of source gas. This paper demonstrates the novel features and utility of the PACES artificial intelligence accelerator controller

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    -pharmacological rheumatology care. Methods: An international, multidisciplinary expert panel comprising 60 clinicians and/or healthcare providers experienced with activity pacing across 12 different countries participated in a Delphi survey. Over four Delphi rounds, the panellists identified and ranked the most important......-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...... future research on activity pacing were formulated and prioritized. Results: Of the 60 panelists, nearly two third (63%) completed all four Delphi rounds. The panel prioritized 9 goals, 11 behaviours, 9 strategies to change behaviour and 10 contextual factors of activity pacing. These items were...

  16. Sky Coverage and Burst Repetition

    OpenAIRE

    Band, David L.

    1996-01-01

    To investigate the repeater content of gamma ray burst samples I develop two models where sources burst at a constant average rate. I find that the sky coverage affects the number of repeaters in a sample predominantly through the detector livetime, and that the number of bursts in the sample is the primary parameter. Thus the repeater content of burst samples should be compared within the context of a repetition model; a direct comparison between two samples is possible only if the samples h...

  17. UWB dual burst transmit driver

    Science.gov (United States)

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Zumstein, James M.; Vigars, Mark L.; Romero, Carlos E.

    2012-04-17

    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.

  18. NEW BURST ASSEMBLY AND SCHEDULING TECHNIQUE FOR OPTICAL BURST SWITCHING NETWORKS

    OpenAIRE

    V.KAVITHA; Palanisamy, V.

    2013-01-01

    The Optical Burst Switching is a new switching technology that efficiently utilizes the bandwidth in the optical layer. The key areas to be concentrated in Optical Burst Switching (OBS) networks are the burst assembly and burst scheduling i.e., assignment of wavelengths to the incoming bursts. This study presents a New Burst Assembly and Scheduling (NBAS) technique in a simultaneous multipath transmission for burst loss recovery in OBS networks. A Redundant Burst Segmentation (RBS) is used fo...

  19. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    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.

  20. Gamma-Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

    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.

  1. Gamma Ray Bursts

    CERN Document Server

    Gehrels, Neil; 10.1126/science.1216793

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day, last typically 10s 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.

  2. Dark Gamma Ray Bursts

    OpenAIRE

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stell...

  3. An Undergraduate Intern Program at PACES

    Science.gov (United States)

    Starks, Scott A.

    1997-01-01

    The University of Texas at El Paso (UTEP) established the Pan American Center for Earth and Environmental Studies (PACES) in 1995 to conduct basic and applied research that contributes to NASA's Mission to Planet Earth. Specifically, PACES provides a repository of remote sensing and other information that supports investigations into an improved understanding of geological, ecological and environmental processes occurring in the southwestern United States and Northern Mexico. Approximately 85% of UTEP's students come from El Paso County, a fast growing urban region representative of many large cities in the Southwest that have, or will soon have, a majority of their population composed of groups currently underrepresented in the scientific and technical workforce. UTEP's student population has an ethnic distribution (63% Hispanic, 32% Anglo, 3% African American, 1.5 % Asian American, and less than 1% Native American) that closely matches the demographics of the region it serves. Thus, UTEP has a mission to serve a multicultural population where minority students comprise the majority. Most Hispanic students at UTEP are primarily of Mexican origin. A large number are first or second-generation U.S. citizens. Characteristics that unite Hispanic students, in particular those of Mexican-origin, are a strong sense of family loyalty and a belief that all family members are responsible for contributing to the economic stability and well-being of the family. Most of their families are larger in number than the national average, and a variety of generations live together or share considerable resources. Thus, many young people feel an obligation and a desire to go to work at a young age and to continue working while in college, thereby assisting their parents and other family members. Older siblings understand that they have responsibilities to do household chores, to aid their younger siblings economically, and to assist elderly family members. This "work ethic" within the

  4. 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;

    2011-01-01

    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 ...

  5. 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.

  6. Dark Gamma Ray Bursts

    CERN Document Server

    Brdar, Vedran; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p-wave process than for s-wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to Standard Model particles later, the annihilation bu...

  7. Burst propagation in Texas Helimak

    Science.gov (United States)

    Pereira, F. A. C.; Toufen, D. L.; Guimarães-Filho, Z. O.; Caldas, I. L.; Gentle, K. W.

    2016-05-01

    We present investigations of extreme events (bursts) propagating in the Texas Helimak, a toroidal plasma device in which the radial electric field can be changed by application of bias. In the experiments analyzed, a large grid of Langmuir probes measuring ion saturation current fluctuations is used to study the burst propagation and its dependence on the applied bias voltage. We confirm previous results reported on the turbulence intermittency in the Texas Helimak, extending them to a larger radial interval with a density ranging from a uniform decay to an almost uniform value. For our analysis, we introduce an improved procedure, based on a multiprobe bidimensional conditional averaging method, to assure precise determination of burst statistical properties and their spatial profiles. We verify that intermittent bursts have properties that vary in the radial direction. The number of bursts depends on the radial position and on the applied bias voltage. On the other hand, the burst characteristic time and size do not depend on the applied bias voltage. The bias voltage modifies the vertical and radial burst velocity profiles differently. The burst velocity is smaller than the turbulence phase velocity in almost all the analyzed region.

  8. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

    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.

  9. Burst Mode Transmission in GPON

    Institute of Scientific and Technical Information of China (English)

    LI Liang-chuan; ZHANG Yan-gan; LI Ling; XU Da-xiong

    2004-01-01

    In this paper, a newly approved standard G.984 for Gigabit-capable Passive Optical Networks (GPON) is introduced. Technical challenges about high-speed burst-mode data transmission in GPON are discussed and key issues such as Forward Error Correction (FEC), timing to uplink performance of burst mode are high-lighted.

  10. Scheduling start time in CDMA burst admission

    OpenAIRE

    Zhuge, L; Li, VOK

    2002-01-01

    Burst transmission protocols have been proposed in the next generation CDMA cellular systems to support short-time high-speed data communications. The existing burst admission algorithm considers only the current interference condition in the system. The burst transmission request will be rejected if the interference in the system will exceed the acceptable level with the burst admitted. In this paper we propose a new burst admission algorithm where a currently-unacceptable burst request can ...

  11. Burst Detector Sensitivity: Past, Present & Future

    OpenAIRE

    Band, David L.

    2006-01-01

    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...

  12. Pacing-Induced Non-Uniform Ca2+ Dynamics in Rat Atria Revealed by Rapid-Scanning Confocal Microscopy

    International Nuclear Information System (INIS)

    Intracellular Ca2+ ([Ca2+]i) dynamics in isolated myocytes differ between the atria and ventricles due to the distinct t-tubular distributions. Although cellular aspects of ventricular [Ca2+]i dynamics in the heart have been extensively studied, little is known about those of atrial myocytes in situ. Here we visualized precise [Ca2+]i dynamics of atrial myocytes in Langendorff-perfused rat hearts by rapid-scanning confocal microscopy. Of 16 fluo-4-loaded hearts imaged during pacing up to 4-Hz, five hearts showed spatially uniform Ca2+ transients on systole among individual cells, whereas no discernible [Ca2+]i elevation developed during diastole. In contrast, the remaining hearts showed non-uniform [Ca2+]i dynamics within and among the cells especially under high-frequency (4 Hz) excitation, where subcellular cluster-like [Ca2+]i rises or wave-like [Ca2+]i propagation occurred on excitation. Such [Ca2+]i inhomogeneity was more pronounced at high-frequency pacing, showing beat-to-beat Ca2+ transient alternans. Despite such non-uniform dynamics, cessation of burst pacing of the atria was not followed by emergence of spontaneous Ca2+ waves, indicating minor Ca2+-releasing potentials of the sarcoplasmic reticulum (SR). In summary, rat atria display a propensity to show non-uniform [Ca2+]i dynamics on systole due to impaired Ca2+-release from the SR and paucity of t-tubules. Our results provide an important basis for understanding atrial pathophysiology

  13. Development of Pacing, Electrophysiology and Defibrillation in India

    OpenAIRE

    Nair, Mohan; Francis, Johnson; Venugopal, K

    2002-01-01

    History of cardiac pacing in India dates back to late 1960s. Kar1 reported that cardiac pacing was introduced in India in 1966. Basu2 while discussing on cardiac pacemaking in Calcutta, mentions that the first pacing was performed in April 1967 at the Institute of Post Graduate Medical Education and Research (IPGME&R). Bhatia et al3 started pacemaker implantation at AIIMS, New Delhi in 1968. Their first patient was a doctor from Assam and the pulse generator was supplied by Medtronic Inc. Th...

  14. Quantum key based burst confidentiality in optical burst switched networks.

    Science.gov (United States)

    Balamurugan, A M; Sivasubramanian, A

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS). This paper deals with employing RC4 (stream cipher) to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks. PMID:24578663

  15. Determination of myocardial energetic output for cardiac rhythm pacing

    OpenAIRE

    Heřman, Dalibor; Převorovská, Světlana; Maršík, František

    2007-01-01

    This research is aimed to the determination of the changes in the cardiac energetic output for three different modes of cardiac rhythm pacing. The clinical investigation of thirteen patients with the permanent dual-chamber pacemaker implantation was carried out. The patients were taken to echocardiography examination conducted by way of three pacing modes (AAI, VVI and DDD). The myocardial energetic parameters—the stroke work index (SWI) and the myocardial oxygen consumption (MVO2) are not di...

  16. Factors explaining voluntary participation in PACE-Vaquita

    OpenAIRE

    Sara Avila

    2011-01-01

    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...

  17. Concept for LEU Burst Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kimpland, Robert Herbert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-07

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

  18. Concept for LEU Burst Reactor

    International Nuclear Information System (INIS)

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zimring, Mark; Fuller, Merrian

    2010-03-17

    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.

  20. The Pace of Perceivable Extreme Climate Change

    Science.gov (United States)

    Tan, X.; Gan, T. Y.

    2015-12-01

    When will the signal of obvious changes in extreme climate emerge over climate variability (Time of Emergence, ToE) is a key question for planning and implementing measures to mitigate the potential impact of climate change to natural and human systems that are generally adapted to potential changes from current variability. We estimated ToEs for the magnitude, duration and frequency of global extreme climate represented by 24 extreme climate indices (16 for temperature and 8 for precipitation) with different thresholds of the signal-to-noise (S/N) ratio based on projections of CMIP5 global climate models under RCP8.5 and RCP4.5 for the 21st century. The uncertainty of ToE is assessed by using 3 different methods to calculate S/N for each extreme index. Results show that ToEs of the projected extreme climate indices based on the RCP4.5 climate scenarios are generally projected to happen about 20 years later than that for the RCP8.5 climate scenarios. Under RCP8.5, the projected magnitude, duration and frequency of extreme temperature on Earth will all exceed 2 standard deviations by 2100, and the empirical 50th percentile of the global ToE for the frequency and magnitude of hot (cold) extreme are about 2040 and 2054 (2064 and 2054) for S/N > 2, respectively. The 50th percentile of global ToE for the intensity of extreme precipitation is about 2030 and 2058 for S/N >0.5 and S/N >1, respectively. We further evaluated the exposure of ecosystems and human societies to the pace of extreme climate change by determining the year of ToE for various extreme climate indices projected to occur over terrestrial biomes, marine realms and major urban areas with large populations. This was done by overlaying terrestrial, ecoregions and population maps with maps of ToE derived, to extract ToEs for these regions. Possible relationships between GDP per person and ToE are also investigated by relating the mean ToE for each country and its average value of GDP per person.

  1. Interference Resilience of Burst-by-burst Adaptive Modems

    OpenAIRE

    Torrance, J.M.; Hanzo, L.; Keller, T

    1997-01-01

    Adaptive modulation can achieve channel capacity gains by adapting t h e number of bits per transmission symbol on a burst-by-burst basis, in harmony with channel quality fluctuations. In this treatise their interference resilience is quantified and the modem mode switching levels are determined under interfered conditions. The associated performance curves are portrayed in Figures 6, 7 and 8 for target bit error rates of 1 and 0.01 %, respectively. The corresponding modem mode switching leve...

  2. Analysis of Burst Assembly Modeling for Optical Burst Switched Network

    Directory of Open Access Journals (Sweden)

    Bhumika Patel

    2013-11-01

    Full Text Available In this paper, we have study the current state of the technology, the Optical burst Switched (OBS network is the most practical in all-optical architecture. Here we define how Burst Assembly will carried out and also here in the network architecture each node is consist of Core router and Edge router. Moreover we define challenges faced at practical implementation of OBS and proposed its unique solution at the node as Delay model.

  3. Effects of gastric pacing on gastric emptying and plasma motilin

    Institute of Scientific and Technical Information of China (English)

    Min Yang; Dian-Chun Fang; Qian-Wei Li; Nian-Xu Sun; Qing-Lin Long; Jian-Feng Sui; Lu Gan

    2004-01-01

    AIM: To invertigate the effects of gastric pacing on gastric emptying and plasma motilin level in a canine model of gastric motility disorders and the correlation between gastric emptying and plasma motilin level.METHODS: Ten healthy Mongrel dogs were divided into:experimental group of six dogs and control group of four dogs. A model of gastric motility disorders was established in the experimental group undergone truncal vagotomy combined with injection of glucagon. Gastric half-emptying time (GEt1/2) was monitored with single photon emission computerized tomography (SPECT), and the half-solid test meal was labeled with an isotope-99m Tc sulfur colloid. Plasma motilin concentration was measured with radioimmunoassay (RIA) kit. Surface gastric pacing at 1.1-1.2 times the intrinsic slow-wave frequency and a superimposed series of high frequency pulses (10-30 Hz) was performed for 45 min daily for a month in conscious dogs.RESULTS: After surgery, GEt1/2 in dogs undergone truncal vagotomy was increased significantly from 56.35±2.99 min to 79.42±l.91 min (P<0.001), but surface gastric pacing markedly accelerated gastric emptying and significantly decreased GEt1/2 to 64,94±l.75 min (P<0.001) in animals undergone vagotomy. There was a significant increase of plasma level of motilin at the phase of IMCⅢ (interdigertive myoelectrical complex, IMCⅢ) in the dogs undergone bilateral truncal vagotomy (baseline vs vagotomy, 184.29±9.81 pg/ml vs 242.09±17,22 pg/ml; P<0.01). But plasma motilin concentration (212.55±11.20 pg/ml; P<0.02) was decreased significantly after a long-term treatment with gastric pacing.Before gastric pacing, GEt1/2 and plasma motilin concentration of the dogs undergone vagotomy showed a positive correlation (r=0.867, P<0.01), but after a long-term gastric pacing, GEt1/2 and motilin level showed a negative correlation (r=-0.733, P<0,04).CONCLUSION: Surface gastric pacing with optimal pacing parameters can improve gastric emptying

  4. FERMIGBRST - Fermi GBM Burst Catalog

    Data.gov (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...

  5. SWIFT and BATSE bursts' classification

    CERN Document Server

    Horvath, I; Balazs, L G; Tusnady, G; Veres, P

    2009-01-01

    Two classes of gamma-ray bursts were identified in the BATSE catalogs characterized by their durations. There were also some indications for the existence of a third type of gamma-ray bursts. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for GRBs. Therefore in this paper we analyze the bursts' duration distribution and also the duration-hardness bivariate distribution, published in The First BAT Catalog. Similarly to the BATSE data, to explain the BAT GRBs' duration distribution three components are needed. Although, the relative frequencies of the groups are different than they were in the BATSE GRB sample, the difference in the instrument spectral sensitivities can explain this bias in a natural way. This means theoretical models may have to explain three different type of gamma-ray bursts.

  6. Biomechanically and electromyographically assessed load on the spine in self-paced and force-paced lifting work.

    Science.gov (United States)

    Leskinen, T P; Stålhammar, H R; Rautanen, M T; Troup, J D

    1992-01-01

    The purpose of this study was to measure dose of spinal load when different pacing methods were applied to lifting work and to develop methodology for such measurements. The compressive load on the spine computed by a dynamic biomechanical model and the electromyographic activity of back muscles were used for describing the spinal load. Five men and five women worked in a laboratory on two days lifting a box up and down for 30 min on both days, on one day force-paced (4 lifts/min), and on the other self-paced in random order. The weight of the box was rated by the subjects to be acceptable for the work done. The lift rate of our female subjects was higher and that of the male subjects lower in self-paced than in force-paced work. There were no significant differences in peak lumbosacral compressions nor in the amplitude distributions of electromyography between the two pacing methods. The biomechanically-calculated compressive forces on the spine were lower (about 2.7 kN for the men and 2.3 kN for women) than the biomechanical recommendations for safe lifting, but the EMG activity showed quite high peaks so that for 1% of work time the activity was on women above 60% and on men above 40% of the activity during maximum isometric voluntary test contraction. PMID:1633794

  7. The effects of fluid ingestion on free-paced intermittent-sprint performance and pacing strategies in the heat.

    Science.gov (United States)

    Skein, Melissa; Duffield, Rob

    2010-02-01

    The purpose of this study was to examine the effects of fluid ingestion on pacing strategies and performance during intermittent-sprint exercise in the heat. Nine male rugby players performed a habituation session and 2 x 50-min intermittent-sprint protocols at a temperature of 31 degrees C, either with or without fluid. Participants were informed of a third session (not performed) to ensure that they remained blind to all respective conditions. The protocol consisted of a 15-m sprint every minute separated by self-paced bouts of hard running, jogging, and walking for the remainder of the minute. Sprint time, distance covered during self-paced exercise, and vertical jump height before and after exercise were recorded. Heart rate, core temperature, nude mass, capillary blood haematocrit, pH, lactate concentration, perceptual ratings of perceived exertion, thermal stress, and thirst were also recorded. Sprint times (fluid vs. no-fluid: 2.82 +/- 0.11 vs. 2.82 +/- 0.14) and distance covered during self-paced exercise (fluid vs. no-fluid: 4168 +/- 419 vs. 3981 +/- 263 m) were not different between conditions (P = 0.10-0.98) but were progressively reduced to a greater extent in the no-fluid trial (7 +/- 13%) (d = 0.56-0.58). There were no differences (P = 0.22-1.00; d = affect pacing strategies with a greater reduction in distance covered of self-paced exercise during the no-fluid trial. PMID:20077276

  8. Disinhibition Bursting of Dopaminergic Neurons

    Directory of Open Access Journals (Sweden)

    Collin J Lobb

    2011-05-01

    Full Text Available Substantia nigra pars compacta (SNpc dopaminergic neurons receive strong tonic inputs from GABAergic neurons in the substantia nigra pars reticulata (SNpr and globus pallidus (GP, and glutamatergic neurons in the subthalamic nucleus. The presence of these tonic inputs raises the possibility that phasic disinhibition may trigger phasic bursts in dopaminergic neurons. We first applied constant NMDA and GABAA conductances onto a two-compartment single cell model of the dopaminergic neuron (Kuznetsov et al., 2006. The model exhibited disinhibition bursting upon stepwise removal of inhibition. A further bifurcation analysis suggests that disinhibition may be more robust than excitation alone in that for most levels of NMDA conductance, the cell remains capable of bursting even after a complete removal of inhibition, whereas too much excitatory input will drive the cell into depolarization block. To investigate the network dynamics of disinhibition, we used a modified version of an integrate-and-fire based model of the basal ganglia (Humphries et al., 2006. Synaptic activity generated in the network was delivered to the two-compartment single cell dopaminergic neuron. Phasic activation of the D1-expressing medium spiny neurons in the striatum (D1STR produced disinhibition bursts in dopaminergic neurons through the direct pathway (D1STR to SNpr to SNpc. Anatomical studies have shown that D1STR neurons have collaterals that terminate in GP. Adding these collaterals to the model, we found that striatal activation increased the intra-burst firing frequency of the disinhibition burst as the weight of this connection was increased. Our studies suggest that striatal activation is a robust means by which disinhibition bursts can be generated by SNpc dopaminergic neurons, and that recruitment of the indirect pathway via collaterals may enhance disinhibition bursting.

  9. Chimera states in bursting neurons

    OpenAIRE

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2015-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of stability function in the incoherent (i.e. disorder), coherent, chimera and multi-chimera states. Surprisingly, we find that chimera and multi-chimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is i...

  10. Burst Suppression: A Review and New Insights

    OpenAIRE

    Jonathan Dillon Kenny; M. Brandon Westover; ShiNung Ching; Brown, Emery N.; Ken Solt

    2014-01-01

    Burst suppression is a pattern of brain electrical activity characterized by alternating periods of high-amplitude bursts and electrical silence. Burst suppression can arise from several different pathological conditions, as well as from general anesthesia. Here we review current algorithms that are used to quantify burst suppression, its various etiologies, and possible underlying mechanisms. We then review clinical applications of anesthetic-induced burst suppression. Finally, we report the...

  11. Mining Gamma-Ray Burst Data

    OpenAIRE

    Hakkila, Jon; Roiger, Richard J.; Haglin, David J.; Mallozzi, Robert S.; Pendleton, Geoffrey N.; Meegan, Charles A.

    2000-01-01

    Gamma-ray bursts provide what is probably one of the messiest of all astrophysical data sets. Burst class properties are indistinct, as overlapping characteristics of individual bursts are convolved with effects of instrumental and sampling biases. Despite these complexities, data mining techniques have allowed new insights to be made about gamma-ray burst data. We demonstrate how data mining techniques have simultaneously allowed us to learn about gamma-ray burst detectors and data collectio...

  12. Evaluation of Burst Loss Rate of an Optical Burst Switching (OBS) Network with Wavelength Conversion Capability

    OpenAIRE

    Reza, Md. Shamim; Hossain, Md. Maruf; Majumder, Satya Prasad

    2010-01-01

    This paper presents a new analytical model for calculating burst loss rate (BLR) in a slotted optical burst switched network. The analytical result leads to a framework which provides guidelines for optical burst switched networks. Wavelength converter is used for burst contention resolution. The effect of several design parameters such as burst arrival probability, wavelength conversion capability, number of slots per burst and number of wavelengths is incorporated on the above performance m...

  13. Pacing accuracy during an incremental step test in adolescent swimmers

    Directory of Open Access Journals (Sweden)

    Scruton A

    2015-08-01

    Full Text Available Adrian Scruton, James Baker, Justin Roberts, Itay Basevitch, Viviane Merzbach, Dan Gordon Sport and Exercise Sciences Research Group, Anglia Ruskin University, Cambridge, UK Abstract: To assess pacing accuracy in a group of adolescent swimmers during an incremental step test. Fifteen well-trained swimmers (age 15±1.5 years; height 170.2±8.8 cm; mass 60.2±6.6 kg, completed two 7×200 m tests, separated by ~72 hours. They swam to a predetermined incrementally increasing pace per step and were instructed to swim at even pace. Upon completion of each step, rating of perceived exertion, heart rate and blood lactate were recorded. Significant differences observed for both trials between actual and predicted swim time (P<0.05. Significant differences also observed between the first and second 100 m of each step in trial 1 for step 1 (P=0.001, effect size [ES] =0.54, step 2 (P=0.0001, ES =0.57, step 4 (P=0.0001, ES =0.53, step 5 (P=0.005, ES =0.65, step 6 (P=0.0001, ES =0.50, and step 7 (P=0.0001, ES =0.70. Similar responses witnessed for trial 2 (P<0.05. Findings suggest that the finite anaerobic capacity was engaged sooner than would normally be anticipated, as a function of an inability to regulate pace. This is proposed to be a consequence of the volume of exposure to the biological and psychological sensations and cognitive developmental status. Given the apparent error in pacing judgment exhibited in this population group, caution should be applied when adopting such tests to monitor training responses with adolescent athletes, and alternate means of modulating pace be investigated. Keywords: effort regulation, children, exercise testing, perception

  14. Social Interaction in Self-paced Distance Education

    OpenAIRE

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

    2015-01-01

    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 int...

  15. EFFECTS OF MUSIC ON PERCEPTUAL RESPONSES AND PACING STRATEGY

    OpenAIRE

    Flávio de Oliveira Pires; Rômulo Cássio de Moraes Bertuzzi; Adriano Eduardo Lima-Silva; Agedani Pacheco Correia do Rozario; Ana Gabriela de M. Simões; João Paulo Lopes da Silva; Marcos David da Silva-Cavalcante; Thomaz Roberto Carvalho Carnaúba; Fernando Roberto de-Oliveira

    2011-01-01

    CARNAÚBA, T. R. C.; SILVA-CAVALCANTE, M. D.; SILVA, J. P. L.; SIMÕES, A. G. M.; 1, ROZARIO, A. P. C.; BERTUZZI, R. C. M.; PIRES, F. O.; DE-OLIVEIRA, F. R.; LIMA-SILVA, A. E. Effects of music on perceptual responses and pacing strategy. Brazilian Journal of Biomotricity. v. 5, n. 3, p. 210-220, 2011. The purpose of this study was verify the effects of music on perceptual responses and pacing strategy during 5-km running. Fifteen men (22.5 ± 3.5 years; 177.7 ± 6 cm; 76.0 ± 7.0 kg) they accom...

  16. International piping benchmarks: Use of simplified code PACE 2

    International Nuclear Information System (INIS)

    This report compares the results obtained using the code PACE 2 with the International Working Group on Fast Reactors (IWGFR) International Piping Benchmark solutions. PACE 2 is designed to analyse systems of pipework using a simplified method which is economical of computer time and hence inexpensive. This low cost is not achieved without some loss of accuracy in the solution, but for most parts of a system this inaccuracy is acceptable and those sections of particular importance may be reanalysed using more precise methods in order to produce a satisfactory analysis of the complete system at reasonable cost. (author)

  17. Chimera states in bursting neurons

    Science.gov (United States)

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2016-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global, and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of the stability function in the incoherent (i.e., disorder), coherent, chimera, and multichimera states. Surprisingly, we find that chimera and multichimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is in contrast with the existence of chimera states in populations of nonlocally or globally coupled oscillators. A chemical synaptic coupling function is used which plays a key role in the emergence of chimera states in bursting neurons. The existence of chimera, multichimera, coherent, and disordered states is confirmed by means of the recently introduced statistical measures and mean phase velocity.

  18. Bursts in intermittent aeolian saltation

    CERN Document Server

    Carneiro, M V; Herrmann, H J

    2014-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of intermittent flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the critical Shields number $\\theta_c$. The time delay between each burst decreases on average with the increase of the Shields number until saltation becomes non-intermittent and the sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain intermittent flux even below the threshold $\\theta_c$ for natural saltation initiation.

  19. Investigating possible ethnicity and sex bias in clinical examiners: an analysis of data from the MRCP(UK) PACES and nPACES examinations

    OpenAIRE

    McManus, I C; Elder, A T; DACRE, J

    2013-01-01

    Background Bias of clinical examiners against some types of candidate, based on characteristics such as sex or ethnicity, would represent a threat to the validity of an examination, since sex or ethnicity are ‘construct-irrelevant’ characteristics. In this paper we report a novel method for assessing sex and ethnic bias in over 2000 examiners who had taken part in the PACES and nPACES (new PACES) examinations of the MRCP(UK). Method PACES and nPACES are clinical skills examinations that have ...

  20. US Army Nuclear Burst Detection System (NBDS)

    International Nuclear Information System (INIS)

    The Nuclear Burst Detection System (NBDS) was developed to meet the Army requirements of an unattended, automatic nuclear burst reporting system. It provides pertinent data for battlefield commanders on a timely basis with high reliability

  1. Preemption window for burst differentiation in OBS

    OpenAIRE

    Klinkowski, Miroslaw; Careglio, Davide; Morató, Daniel; Solé Pareta, Josep

    2008-01-01

    This paper presents a novel control architecture for optical burst switching networks to efficiently apply burst preemption without the resources overbooking, which is specific to conventional OBS. Simulation results prove the effectiveness of this proposal.

  2. Gait coordination after stroke: Benefits of acoustically paced treadmill walking

    NARCIS (Netherlands)

    Roerdink, Melvyn; Lamoth, Claudine J.C.; Kwakkel, Gert; Van Wieringen, Piet C.W.; Beek, Peter J.

    2007-01-01

    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 st

  3. Self-Paced Physics, Segments 24-27.

    Science.gov (United States)

    New York Inst. of Tech., Old Westbury.

    Four study segments of the Self-Paced Physics Course materials are presented in this fifth problems and solutions book used as a part of student course work. The subject matter is related to work in electric fields, potential differences, parallel plates, electric potential energies, potential gradients, capacitances, and capacitor circuits.…

  4. Determination of myocardial energetic output for cardiac rhythm pacing

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

    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

  5. Self-paced training for quality control inspectors

    International Nuclear Information System (INIS)

    The authors discuss the need for quality control (QC) training in the nuclear industry and propose requirements for QC training. This paper presents an overview of a self-paced training program for QC, including the characteristics and structure of such a program

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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 cha...

  7. Hardware packet pacing using a DMA in a parallel computer

    Science.gov (United States)

    Chen, Dong; Heidelberger, Phillip; Vranas, Pavlos

    2013-08-13

    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.

  8. "Set the Pace": Nutrition Education DVD for Head Start Parents

    Science.gov (United States)

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

    2013-01-01

    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.)

  9. Self-Paced Physics, Segments 28-31.

    Science.gov (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…

  10. MFTF-B PACE tests and final cost report

    International Nuclear Information System (INIS)

    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

  11. 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.

    2007-01-01

    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 st

  12. Detecting pipe bursts by monitoring water demand

    NARCIS (Netherlands)

    Bakker, M.; Vreeburg, J.H.G.; Van der Roer, M.; Sperber, V.

    2012-01-01

    An algorithm which compares measured and predicted water demands to detect pipe bursts was developed and tested on three data sets of water demand and reported pipe bursts of three years. The algorithm proved to be able to detect bursts where the water loss exceeds 30% of the average water demand in

  13. Periodicities in gamma ray bursts

    International Nuclear Information System (INIS)

    Gamma ray burst models based on magnetic neutron stars face a problem of account for the scarcity of observed periods. Both this scarcity and the typical period found when any is detected are explained if the neutron stars are accreting in binary systems

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

    OpenAIRE

    Abubakar Muhammad Umaru; Muhammad Shafie Abd Latiff; Yahaya Coulibaly

    2014-01-01

    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 sh...

  15. Two-dimensional burst identification codes and their use in burst correction

    OpenAIRE

    1988-01-01

    A new class of codes, called burst identification codes, is defined and studied. These codes can be used to determine the patterns of burst errors. Two-dimensional burst correcting codes can be easily constructed from burst identification codes. The resulting class of codes is simple to implement and has lower redundancy than other comparable codes. The results are pertinent to the study of radiation effects on VLSI RAM chips, which can cause two-dimensional bursts of errors.

  16. Gamma-Ray Bursts: The End Game

    Science.gov (United States)

    Lamb, Don

    1997-11-01

    The nature of gamma-ray bursts has been one of the greatest unsolved mysteries in astrophysics for more than a quarter century. A major reason for this is that no definite counterparts to the bursts could be found at other wavelengths, despite intense efforts spanning more than two decades. Consequently, the study of gamma-ray bursts has been isolated from the rest of astronomy. Scientists studying them have had only the laws of physics and the bursts themselves to guide them in attempting to solve the burst mystery. All of this changed dramatically with the discovery earlier this year of fading X-ray and optical sources in the arcminute-sized positional error boxes of several gamma-ray bursts. For the first time, temporal, as well as spatial, coincidence could be used to associate these X-ray and optical sources with the gamma-ray bursts. As a result, the odds are great that the fading X-ray and optical sources are counterparts of the bursts, and that the study of gamma-ray bursts has finally been connected with the rest of astronomy. In this talk, we describe the dramatic new information about the nature of gamma-ray bursts that the X-ray, optical, and radio observations of the fading sources have provided, and emphasize the implications that this information has for the distance scale to the bursts.

  17. Quantum Key Based Burst Confidentiality in Optical Burst Switched Networks

    OpenAIRE

    Balamurugan, A. M.; A. Sivasubramanian

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The...

  18. Bubbles and Monetary Policy: To Burst or not to Burst?

    OpenAIRE

    König, Philipp; POTHIER, David

    2015-01-01

    The question of whether monetary policy should target asset prices remains a contentious issue. Prior to the 2007/08 financial crisis, central banks opted for a wait-and-see approach, remaining passive during the build-up of asset price bubbles but actively seeking to stabilize prices and output after they burst. The macroeconomic and financial turbulence that followed the subprime housing bubble has led to a renewed debate concerning monetary policy’s role in maintaining financial stability....

  19. Spindle Bursts in Neonatal Rat Cerebral Cortex.

    Science.gov (United States)

    Yang, Jenq-Wei; Reyes-Puerta, Vicente; Kilb, Werner; Luhmann, Heiko J

    2016-01-01

    Spontaneous and sensory evoked spindle bursts represent a functional hallmark of the developing cerebral cortex in vitro and in vivo. They have been observed in various neocortical areas of numerous species, including newborn rodents and preterm human infants. Spindle bursts are generated in complex neocortical-subcortical circuits involving in many cases the participation of motor brain regions. Together with early gamma oscillations, spindle bursts synchronize the activity of a local neuronal network organized in a cortical column. Disturbances in spindle burst activity during corticogenesis may contribute to disorders in cortical architecture and in the activity-dependent control of programmed cell death. In this review we discuss (i) the functional properties of spindle bursts, (ii) the mechanisms underlying their generation, (iii) the synchronous patterns and cortical networks associated with spindle bursts, and (iv) the physiological and pathophysiological role of spindle bursts during early cortical development. PMID:27034844

  20. What Pace Is Best? Assessing Adults' Learning from Slideshows and Video

    Science.gov (United States)

    Sage, Kara

    2014-01-01

    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)…

  1. "U-Pace" Instruction: Improving Student Success by Integrating Content Mastery and Amplified Assistance

    Science.gov (United States)

    Reddy, Diane M.; Pfeiffer, Heidi M.; Fleming, Raymond; Ports, Katie A.; Pedrick, Laura E.; Barnack-Tavlaris, Jessica L.; Jirovec, Danielle L.; Helion, Alicia M.; Swain, Rodney A.

    2013-01-01

    "U-Pace," an instructional intervention, has potential for widespread implementation because student behavior recorded in any learning management system is used by "U-Pace" instructors to tailor coaching of student learning based on students' strengths and motivations. "U-Pace" utilizes an online learning…

  2. Society for the Teaching of Psychology and the University of Wisconsin-Milwaukee: U-Pace

    Science.gov (United States)

    EDUCAUSE, 2014

    2014-01-01

    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…

  3. Optimal pacing strategy for a race of two competing cyclists

    OpenAIRE

    Dahmen, Thorsten; Saupe, Dietmar

    2014-01-01

    For optimal pacing strategies in the case of two or more competing or cooperating cyclists only few approaches take slipstreaming into account. However, by incorporating the slipstream effect in the model of a race of two runners on a flat course , it has been shown, how the trailing runner can position himself at striking distance behind the other and when he should start the final sprint. (Pitcher, 2009: Optimal strategies for a two - runner model of middle - distance running. SIAM Journal ...

  4. Programming the programme: pacing the curriculum in architectural education

    OpenAIRE

    Holgate, Peter; Roberts, Stephen

    2012-01-01

    Constructive alignment in project based learning provides the opportunity to ‘entrap students in a web of consistency’ (Biggs, 1999). While the central design of a curriculum can incorporate the core elements of a syllabus for successful alignment, consideration of pace and timing of content delivery, assessment and learning opportunities can enhance student engagement and satisfaction. This paper draws upon a case study of the second year architecture curriculum at Northumbria University....

  5. Hemodynamic aspects of biventricular pacing in heart failure

    OpenAIRE

    Ståhlberg, Marcus

    2010-01-01

    Background and aims Biventricular pacing or cardiac resynchronization therapy (CRT) is an established treatment option for selected heart failure (HF) patients. We aimed at evaluating acute and longer-term hemodynamic effects of different pacemaker programmings in CRT patients. For the latter purpose, 10 CRT patients also received an implantable hemodynamic monitor (IHM), allowing for long-term hemodynamic monitoring during ambulatory periods. Study I The hemodynamic ...

  6. Recognition of ventricular fibrillation concomitant with pacing artifacts

    OpenAIRE

    Zysko, Dorota; Smereka, Jacek; CHÊCIÑSKI, IGOR; WRÓBLEWSKI, PAWE£; TERPI£OWSKI, £UKASZ; JACEK, GAJEK; WALDEMAR, GOZDZIK; KUMAR AGRAWAL, ANIL

    2013-01-01

    Introduction. In pre-hospital settings recognition of underlying rhythm in patients with ventricular stimulation can be difficult especially when a 3-lead electrocardiogram (ECG) is analyzed. This fact is particularly important in patients with life-threatening cardiac dysrhythmias. The pacing spikes in the ECG of a patient with cardiac arrest due to ventricular fibrillation may be misdiagnosed as QRS complexes. Aim of the study. The aim of this study was to assess emergency medical care stud...

  7. Determination of myocardial energetic output for cardiac rhythm pacing.

    Science.gov (United States)

    Herman, Dalibor; Prevorovská, Svetlana; Marsík, Frantisek

    2007-12-01

    This research is aimed to the determination of the changes in the cardiac energetic output for three different modes of cardiac rhythm pacing. The clinical investigation of thirteen patients with the permanent dual-chamber pacemaker implantation was carried out. The patients were taken to echocardiography examination conducted by way of three pacing modes (AAI, VVI and DDD). The myocardial energetic parameters-the stroke work index (SWI) and the myocardial oxygen consumption (MVO2) are not directly measurable, however, their values can be determined using the numerical model of the human cardiovascular system. The 24-segment hemodynamical model (pulsating type) of the human cardiovascular system was used for the numerical simulation of the changes of myocardial workload for cardiac rhythm pacing. The model was fitted by well-measurable parameters for each patient. The calculated parameters were compared using the two-tailed Student's test. The differences of SWI and MVO2 between the modes AAI and VVI and the modes DDD and VVI are statistically significant (P0.05). PMID:18080208

  8. MRI with cardiac pacing devices – Safety in clinical practice

    Energy Technology Data Exchange (ETDEWEB)

    Kaasalainen, Touko, E-mail: touko.kaasalainen@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Department of Physics, University of Helsinki (Finland); Pakarinen, Sami, E-mail: sami.pakarinen@hus.fi [HUS Department of Cardiology, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Kivistö, Sari, E-mail: sari.kivisto@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Holmström, Miia, E-mail: miia.holmstrom@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Hänninen, Helena, E-mail: helena.hanninen@hus.fi [HUS Department of Cardiology, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Peltonen, Juha, E-mail: juha.peltonen@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Helsinki (Finland); Lauerma, Kirsi, E-mail: kirsi.lauerma@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland); Sipilä, Outi, E-mail: outi.sipila@hus.fi [HUS Medical Imaging Center, Helsinki University Central Hospital, POB 340 (Haartmaninkatu 4), 00290 Helsinki (Finland)

    2014-08-15

    Objectives: The aim of this study was to introduce a single centre “real life” experience of performing MRI examinations in clinical practice on patients with cardiac pacemaker systems. Additionally, we aimed to evaluate the safety of using a dedicated safety protocol for these patients. Materials and methods: We used a 1.5 T MRI scanner to conduct 68 MRI scans of different body regions in patients with pacing systems. Of the cardiac devices, 32% were MR-conditional, whereas the remaining 68% were MR-unsafe. We recorded the functional parameters of the devices prior, immediately after, and approximately one month after the MRI scanning, and compared the device parameters to the baseline values. Results: All MRI examinations were completed safely, and each device could be interrogated normally following the MRI. We observed no changes in the programmed parameters of the devices. For most of the participants, the distributions of the immediate and one-month changes in the device parameters were within 20% of the baseline values, although some changes approached clinically important thresholds. Furthermore, we observed no differences in the variable changes between MR-conditional and MR-unsafe pacing systems, or between scans of the thorax area and other scanned areas. Conclusion: MRI in patients with MR-conditional pacing systems and selected MR-unsafe systems could be performed safely under strict conditions in this study.

  9. Factors affecting the regulation of pacing: current perspectives

    Directory of Open Access Journals (Sweden)

    Mauger AR

    2014-09-01

    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

  10. Optimizing classroom instruction through self-paced learning prototype

    Directory of Open Access Journals (Sweden)

    Romiro Gordo Bautista

    2015-09-01

    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.

  11. MRI with cardiac pacing devices – Safety in clinical practice

    International Nuclear Information System (INIS)

    Objectives: The aim of this study was to introduce a single centre “real life” experience of performing MRI examinations in clinical practice on patients with cardiac pacemaker systems. Additionally, we aimed to evaluate the safety of using a dedicated safety protocol for these patients. Materials and methods: We used a 1.5 T MRI scanner to conduct 68 MRI scans of different body regions in patients with pacing systems. Of the cardiac devices, 32% were MR-conditional, whereas the remaining 68% were MR-unsafe. We recorded the functional parameters of the devices prior, immediately after, and approximately one month after the MRI scanning, and compared the device parameters to the baseline values. Results: All MRI examinations were completed safely, and each device could be interrogated normally following the MRI. We observed no changes in the programmed parameters of the devices. For most of the participants, the distributions of the immediate and one-month changes in the device parameters were within 20% of the baseline values, although some changes approached clinically important thresholds. Furthermore, we observed no differences in the variable changes between MR-conditional and MR-unsafe pacing systems, or between scans of the thorax area and other scanned areas. Conclusion: MRI in patients with MR-conditional pacing systems and selected MR-unsafe systems could be performed safely under strict conditions in this study

  12. Pulse Phase Dependence of the Magnetar Bursts

    Indian Academy of Sciences (India)

    Chetana Jain; Anjan Dutta; Biswajit Paul

    2007-12-01

    We report here results from a study of X-ray bursts from 3 magnetar candidates (SGR 1806–20, SGR 1900+14 and AXP 1E 2259+586). We have searched for a pulse phase dependence of the X-ray burst rate from these sources. X-ray light curves were obtained with the Proportional Counter Array on-board the Rossi X-ray Timing Explorer during the periods of intense burst activity in these sources. On detailed analysis of the three sources, we found a very significant burst rate for all pulsar phases. However, some locations appear to produce bursts slightly more often, rendering the non-isotropic distribution. Only in the case of SGR 1900+14, there is a clear pulse phase dependence of burst rate.

  13. Bursting for enhanced ablation of materials

    Science.gov (United States)

    Hendow, Sami; Rea, Edward; Kosa, Nadhir; Bengtsson, Magnus; Shakir, Sami

    2014-03-01

    A significant enhancement in the rate of material removal is demonstrated using a nanosecond-pulsed UV fiber laser in multi-pulsing burst mode, as compared to the case without bursting. Percussion drilling and scribing of thin-film and bulk material tests show that, in general, laser bursts with increased pulse count and reduced pulse spacing show higher rates of material removal. A considerable improvement in removal rate is demonstrated, when bursting is applied to scribing of mono-crystalline silicon (m-Si) and up to 30% in percussion drilling speed. Likewise, improved material removal is demonstrated for scribing of thin film of indium tin oxide (ITO) on glass or metal film on sapphire. Examples of material processing are given with and without bursting at similar experimental conditions of average power, scan speed, and burst/pulse energies. Experimental results included are for m-Si, ITO thin films on glass, and metal films on sapphire.

  14. United assembly algorithm for optical burst switching

    Institute of Scientific and Technical Information of China (English)

    Jinhui Yu(于金辉); Yijun Yang(杨教军); Yuehua Chen(陈月华); Ge Fan(范戈)

    2003-01-01

    Optical burst switching (OBS) is a promising optical switching technology. The burst assembly algorithm controls burst assembly, which significantly impacts performance of OBS network. This paper provides a new assembly algorithm, united assembly algorithm, which has more practicability than conventional algorithms. In addition, some factors impacting selections of parameters of this algorithm are discussed and the performance of this algorithm is studied by computer simulation.

  15. Ballerina - pirouettes in search of gamma bursts

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik; Hjorth, J.

    1999-01-01

    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...... proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX....

  16. Bubble burst as jamming phase transition

    CERN Document Server

    Nishinari, Katsuhiro; Saito, Yukiko Umeno; Watanabe, Tsutomu

    2010-01-01

    Recently research on bubble and its burst attract much interest of researchers in various field such as economics and physics. Economists have been regarding bubble as a disorder in prices. However, this research strategy has overlooked an importance of the volume of transactions. In this paper, we have proposed a bubble burst model by focusing the transactions incorporating a traffic model that represents spontaneous traffic jam. We find that the phenomenon of bubble burst shares many similar properties with traffic jam formation by comparing data taken from US housing market. Our result suggests that the transaction could be a driving force of bursting phenomenon.

  17. Bursting behaviour in coupled Josephson junctions.

    Science.gov (United States)

    Hongray, Thotreithem; Balakrishnan, J; Dana, Syamal K

    2015-12-01

    We report an interesting bow-tie shaped bursting behaviour in a certain parameter regime of two resistive-capacitative shunted Josephson junctions, one in the oscillatory and the other in the excitable mode and coupled together resistively. The burst emerges in both the junctions and they show near-complete synchronization for strong enough couplings. We discuss a possible bifurcation scenario to explain the origin of the burst. An exhaustive study on the parameter space of the system is performed, demarcating the regions of bursting from other solutions. PMID:26723143

  18. Biventricular stimulation to prevent cardiac desynchronization: rationale, design, and endpoints of the 'Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace)' study.

    Science.gov (United States)

    Funck, Reinhard C; Blanc, Jean-Jacques; Mueller, Hans-Helge; Schade-Brittinger, Carmen; Bailleul, Christophe; Maisch, Bernhard

    2006-08-01

    Despite the deleterious effects of cardiac dyssynchrony and the positive effects of cardiac resynchronization therapy, patients with high-degree atrioventricular block continue to receive desynchronizing right ventricular (RV) pacing systems. Although it is unclear whether the negative effects of RV pacing and left bundle branch block (LBBB) are comparable, and whether they depend on the presence and the degree of structural heart disease, one may hypothesize that RV pacing may have similar effects to LBBB. In the BioPace trial, the long-term effects of RV pacing vs. biventricular pacing will be prospectively compared in 1200 pacemaker patients with high likelihood of mostly paced ventricular events, regardless of whether in sinus rhythm or in atrial fibrillation (AF). After echocardiographic examination of left ventricular (LV) function, patients will be randomly assigned to the implantation of an RV vs. a biventricular pacing system and followed for up to 5 years. Primary study endpoints are survival, quality of life (QoL), and the distance covered in a 6-min hall walk (6-MHW) at 24 months after implantation. Secondary endpoints are QoL and the 6-MHW result at 12 months after implantation, hospitalization rate, LV dimensions, LV ejection fraction, and the development of chronic AF and other adverse events. PMID:16864616

  19. Burst Fragmentation Model Based on Sequential Burst Allocation Algorithm for Mobile WiMAX

    OpenAIRE

    Zaid G. Ali; Prof. R. B. Ahmad; Dr. Abid Yahya

    2013-01-01

    the downlink Bandwidth resources of WiMAX are allocated by the burst allocation algorithm. The algorithm is responsible for calculating the appropriate location of a number of the smallest unit of bandwidth which is called the slot for all users within the downlink subframe in the form of bursts. Resource wastage in the form of unused and unallocated slots is a real common problem accompanies resource management in the burst allocation algorithms. This paper investigates the Sequential Burst ...

  20. L-type calcium channels in adrenal chromaffin cells: role in pace-making and secretion.

    Science.gov (United States)

    Marcantoni, A; Baldelli, P; Hernandez-Guijo, J M; Comunanza, V; Carabelli, V; Carbone, E

    2007-01-01

    Voltage-gated L-type (Cav1.2 and Cav1.3) channels are widely expressed in cardiovascular tissues and represent the critical drug-target for the treatment of several cardiovascular diseases. The two isoforms are also abundantly expressed in neuronal and neuroendocrine tissues. In the brain, Cav1.2 and Cav1.3 channels control synaptic plasticity, somatic activity, neuronal differentiation and brain aging. In neuroendocrine cells, they are involved in the genesis of action potential generation, bursting activity and hormone secretion. Recent studies have shown that Cav1.2 and Cav1.3 are also expressed in chromaffin cells but their functional role has not yet been identified despite that L-type channels possess interesting characteristics, which confer them an important role in the control of catecholamine secretion during action potentials stimulation. In intact rat adrenal glands L-type channels are responsible for adrenaline and noradrenaline release following splanchnic nerve stimulation or nicotinic receptor activation. L-type channels can be either up- or down-modulated by membrane autoreceptors following distinct second messenger pathways. L-type channels are tightly coupled to BK channels and activate at relatively low-voltages. In this way they contribute to the action potential hyperpolarization and to the pace-maker current controlling action potential firings. L-type channels are shown also to regulate the fast secretion of the immediate readily releasable pool of vesicles with the same Ca(2+)-efficiency of other voltage-gated Ca(2+) channels. In mouse adrenal slices, repeated action potential-like stimulations drive L-type channels to a state of enhanced stimulus-secretion efficiency regulated by beta-adrenergic receptors. Here we will review all these novel findings and discuss the possible implication for a specific role of L-type channels in the control of chromaffin cells activity. PMID:17561252

  1. Fast radio burst/gamma-ray burst cosmography

    International Nuclear Information System (INIS)

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DMIGM as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D L(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  2. 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

  3. 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)

    2016-03-01

    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.

  4. ECG Database Applicable for Development and Testing of Pace Detection Algorithms

    Directory of Open Access Journals (Sweden)

    Irena Jekova

    2014-12-01

    Full Text Available This paper presents an ECG database, named 'PacedECGdb' (available at http://biomed.bas.bg/bioautomation/2014/vol_18.4/files/PacedECGdb.zip, which contains different arrhythmias generated by HKP (Heidelberger Praxisklinik simulator, combined with artificially superimposed pacing pulses that cover the wide ranges of rising edge (from <10 µs to 100 µs and total pulse durations (from 100 µs to 2 ms and correspond to various pacemaker modes. It involves a total number of 1404 recordings - 780 representing 'pure' ECG with pacing pulses and 624 that comprise paced ECGs corrupted by tremor. The signals are recorded with 9.81 µV/LSB amplitude resolution at 128 kHz sampling rate in order to preserve the steep raising and trailing edges of the pace pulses. To the best of our knowledge, 'PacedECGdb' is the first publicly available paced ECG database. It could be used for development and testing of methods for pace detection in the ECG. The existence of ECGs corrupted by tremor (the only physiological noise that could compromise the methods for pacing pulses detection is an advantage, since such signals could be applied to define the signal-to-noise level for correct operation of the algorithm, or for improvement of the noise immunity of a method that is under development. The open access of the database makes it suitable for comparative studies including different algorithms.

  5. Pacing the right ventricular outflow tract septum: time to embrace the future.

    Science.gov (United States)

    Hillock, Richard J; Mond, Harry G

    2012-01-01

    Transvenous pacing has revolutionized the management of patients with potentially life-threatening bradycardias and at its most basic level ensures rate support to maintain cardiac output. However, we have known for at least a decade that pacing from the right ventricle (RV) apex can induce left ventricle (LV) dysfunction, atrial fibrillation, heart failure, and maybe an increased mortality. Although pacemaker manufacturers have developed successful pacing algorithms designed to minimize unnecessary ventricular pacing, it cannot be avoided in a substantial proportion of pacemaker-dependent patients. Just as there is undoubted evidence that RV apical pacing is injurious, there is emerging evidence that pacing from the RV septum is associated with a shorter duration of activation, improved haemodynamics, and less LV remodelling. The move from traditional RV apical pacing to RV septal pacing requires a change in mindset for many practitioners. The anatomical landmarks and electrocardiograph features of RV septal pacing are well described and easily recognized. While active fixation is required to place the lead on the septum, shaped stylets are now available to assist the implanter. In addition, concerns about the stability and longevity of steroid-eluting active fixation leads have proven to be unfounded. We therefore encourage all implanters to adopt RV septal pacing to minimize the potential of harm to their patients. PMID:21846639

  6. Real burst traffic amplification in optically gain clamped amplifier

    OpenAIRE

    Ennser, Karin; Taccheo, Stefano; Careglio, Davide; Solé Pareta, Josep; Aracil Rico, Javier

    2008-01-01

    Optical burst amplification in a gain-stabilized amplifier is theoretically investigated using real burst traffic data. The results show that excellent performance are obtained for WDM transmission with negligible interplay due to burst arrival statistics.

  7. Cost-based burst dropping strategy in optical burst switching networks

    OpenAIRE

    Klusek, Bartlomiej; Murphy, John; Barry, Liam P.

    2005-01-01

    Optical burst switching (OBS) is a new paradigm for future all-optical networks. Intentional burst dropping is one of techniques used to achieve desired quality of service. In this paper we note that some bursts are more likely to cause contention. We propose a cost function that can be used to predict the likelihood that a given burst will interfere with other traffic, then we explain how, by using this information a new burst dropping strategy can be designed. We compare our method with a r...

  8. Coding Bounds for Multiple Phased-Burst Correction and Single Burst Correction Codes

    OpenAIRE

    Fong, Wai Han

    2011-01-01

    In this paper, two upper bounds on the achievable code rate of linear block codes for multiple phased-burst correction (MPBC) are presented. One bound is constrained to a maximum correctable cyclic burst length within every subblock, or equivalently a constraint on the minimum error free length or gap within every phased-burst. This bound, when reduced to the special case of a bound for single burst correction (SBC), is shown to be the Abramson bound when the cyclic burst length is less than ...

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

    Directory of Open Access Journals (Sweden)

    Andrew eRenfree

    2015-12-01

    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.

  10. Social Interaction in Self-paced Distance Education

    Directory of Open Access Journals (Sweden)

    Terry Anderson

    2015-02-01

    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.

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

    Science.gov (United States)

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

    2016-06-01

    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. PMID:27081672

  12. The Case of the Disappearing Spindle Burst.

    Science.gov (United States)

    Tiriac, Alexandre; Blumberg, Mark S

    2016-01-01

    Sleep spindles are brief cortical oscillations at 10-15 Hz that occur predominantly during non-REM (quiet) sleep in adult mammals and are thought to contribute to learning and memory. Spindle bursts are phenomenologically similar to sleep spindles, but they occur predominantly in early infancy and are triggered by peripheral sensory activity (e.g., by retinal waves); accordingly, spindle bursts are thought to organize neural networks in the developing brain and establish functional links with the sensory periphery. Whereas the spontaneous retinal waves that trigger spindle bursts in visual cortex are a transient feature of early development, the myoclonic twitches that drive spindle bursts in sensorimotor cortex persist into adulthood. Moreover, twitches-and their associated spindle bursts-occur exclusively during REM (active) sleep. Curiously, despite the persistence of twitching into adulthood, twitch-related spindle bursts have not been reported in adult sensorimotor cortex. This raises the question of whether such spindle burst activity does not occur in adulthood or, alternatively, occurs but has yet to be discovered. If twitch-related spindle bursts do occur in adults, they could contribute to the calibration, maintenance, and repair of sensorimotor systems. PMID:27119028

  13. CT Burst Error Weight Enumerator of Array Codes

    OpenAIRE

    Irfan Siap

    2008-01-01

    Recently, CT burst errors originally dened for block codes havebeen generalized to CT burst errors for array codes [6]. In order to establish aRieger's type bound for array codes with respect to CT burst errors. Here, weintroduce a CT burst error weight enumerator whose coecients represent thenumber of CT burst errors of a particular weight. The method of obtainingthe CT burst error weight enumerator is obtained by generating function likeapproach and it does not involve solving equations as ...

  14. IMAGING DIAGNOSIS OF THORACOLUMBAR BURST FRACTURES

    Institute of Scientific and Technical Information of China (English)

    Li-yang Dai

    2004-01-01

    Objective To review imaging use in the diagnosis ofthoracolumbar burst fractures and to determine the diagnostic value of different imaging methods.Methods One hundred and fourteen patients with 120 thoracolumbar burst fractures were retrospectively reviewed. Plain radiographs were available in all cases; CT scans and MRI were obtained in 96 and 74 cases, respectively.Results A total of 27 burst fractures were misdiagnosed as other types of fractures on radiographs alone, and accounted for 22.5% of all fractures. The results indicated that plain radiographs often fail to delineate the pathological features of thoracolumbar burst fractures, leading to delay in diagnosis.Conclusion In regard to thoracolumbar injury diagnosis, burst fractures should be differentiated from compression fractures. CT should be routinely indicated and MRI examination, when necessary, may be simultaneously considered.

  15. Bright 30 THz Impulsive Solar Bursts

    CERN Document Server

    Kaufmann, P; Marcon, R; Kudaka, A S; Cabezas, D P; Cassiano, M M; Francile, C; Fernandes, L O T; Ramirez, R F Hidalgo; Luoni, M; Marun, A; Pereyra, P; de Souza, R V

    2015-01-01

    Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept. The most intense burst was observed together with a GOES X2 class event on October 27, 2014, also detected at two sub-THz frequencies, RHESSI X-rays and SDO/HMI and EUV. It exhibits strikingly good correlation in time and in space with white light flare emission. It is likely that this association may prove to be very common. All three 30 THz events recently observed exhibited intense fluxes in the range of 104 solar flux units, considerably larger than those measured for the same events at microwave and sub-mm wavelengths. The 30 THz burst emission might be part of the same spectral burst component found at sub-THz frequencies. The 30 THz solar bursts open a promising new window for the study of flares at their origin

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

    LENUS (Irish Health Repository)

    D'Ancona, Giuseppe

    2012-02-03

    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.

  17. Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

    Institute of Scientific and Technical Information of China (English)

    LI Bing-Wei; SUN Li-Li; CHEN Bin; YING He-Ping

    2007-01-01

    @@ Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies:for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.

  18. Two unsung heroes of closed-chest cardiac pacing: Green and McWilliam.

    Science.gov (United States)

    Geddes, L A

    1994-07-01

    In the latter half of the last century, cardiorespiratory arrest was not uncommon due to the anesthetic used (chloroform). Animal studies showed that the heart could be paced. One physician (Green) resuscitated 5 of 7 cardiac arrest patients with single stimuli applied to body surface electrodes. Another (McWilliam) issued a proposal for adoption of closed-chest pacing and provided information on the procedure. The following historical footnote describes these pioneering events in the history of cardiac pacing. PMID:7937239

  19. Effects of Amiodarone plus Losartan on Electrical Remodeling in Rapid Atrial Pacing in Rabbits

    Institute of Scientific and Technical Information of China (English)

    Liye Wei; Yue Xia; Guoqing Qi; Qingwen Zhang

    2008-01-01

    Objectives To investigate the electrical remodeling and the effects of amiodarone and losartan on electrical remode-ling in rapid atrial pacing on rabbit model. Methods 40 normal rabbits were randomly divided into 4 groups: the sa-line group (control group), amiodarone group, losartan group, ami + los group. All rabbits were raised drugs in a week. The atrial effective refractory period (AERP) was measured. Then, take a rapid atrial pacing (600 bpm) and the AERP was measured after 0. 5, 1, 2, 4, 6 and 8 hours pacing and 30 minutes after the termination of rapid pacing. Results ① In control group, after 8 hours rapid pacing, AERP 200 and AERP 150 were significantly shortened 16. 11%± 3. 1% (P <0. 01) and 9. 99%±4. 2% (P <0. 01). And the degree of AERP shortening induced by rapid pacing was greater at basic cycle lengths of 200 ms (BCL200) than that at BCL150. The AERP of amiodarone, losartan group and anti + los group were not shortened during rapid pacing.② In the control group, after the termination of rapid pacing, the AERP gradually increased. The AERP at all of the BCLS examined recovered to almost the 95.78% and 96. 76% of baseline values within the first 10 minutes and recovered to almost the 99. 07% and 99. 39% of baseline values within the first 30 minutes. Condusions Short-term atrial rapid pacing can induce the atrial electrical remodeling. Amiodarone and losartan can prevent the electrical remodeling.

  20. Spatiotemporal chaos from bursting dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Berenstein, Igal; De Decker, Yannick [Nonlinear Physical Chemistry Unit and Interdisciplinary Center for Nonlinear Phenomena and Complex Systems (CENOLI), Faculté des Sciences, Université libre de Bruxelles (ULB), Campus Plaine, C.P. 231, B-1050 Brussels (Belgium)

    2015-08-14

    In this paper, we study the emergence of spatiotemporal chaos from mixed-mode oscillations, by using an extended Oregonator model. We show that bursting dynamics consisting of fast/slow mixed mode oscillations along a single attractor can lead to spatiotemporal chaotic dynamics, although the spatially homogeneous solution is itself non-chaotic. This behavior is observed far from the Hopf bifurcation and takes the form of a spatiotemporal intermittency where the system locally alternates between the fast and the slow phases of the mixed mode oscillations. We expect this form of spatiotemporal chaos to be generic for models in which one or several slow variables are coupled to activator-inhibitor type of oscillators.

  1. Observing a Burst with Sunglasses

    Science.gov (United States)

    2003-11-01

    Unique Five-Week VLT Study of the Polarisation of a Gamma-Ray Burst Afterglow "Gamma-ray bursts (GRBs)" are certainly amongst the most dramatic events known in astrophysics. These short flashes of energetic gamma-rays, first detected in the late 1960's by military satellites, last from less than one second to several minutes. GRBs have been found to be situated at extremely large ("cosmological") distances. The energy released in a few seconds during such an event is larger than that of the Sun during its entire lifetime of more than 10,000 million years. The GRBs are indeed the most powerful events since the Big Bang known in the Universe, cf. ESO PR 08/99 and ESO PR 20/00. During the past years circumstantial evidence has mounted that GRBs signal the collapse of extremely massive stars, the so-called hypernovae. This was finally demonstrated some months ago when astronomers, using the FORS instrument on ESO's Very Large Telescope (VLT), documented in unprecedented detail the changes in the spectrum of the light source ("the optical afterglow") of the gamma-ray burst GRB 030329 (cf. ESO PR 16/03). A conclusive and direct link between cosmological gamma-ray bursts and explosions of very massive stars was provided on this occasion. Gamma-Ray Burst GRB 030329 was discovered on March 29, 2003 by NASA's High Energy Transient Explorer spacecraft. Follow-up observations with the UVES spectrograph at the 8.2-m VLT KUEYEN telescope at the Paranal Observatory (Chile) showed the burst to have a redshift of 0.1685 [1]. This corresponds to a distance of about 2,650 million light-years, making GRB 030329 the second-nearest long-duration GRB ever detected. The proximity of GRB 030329 resulted in very bright afterglow emission, permitting the most extensive follow-up observations of any afterglow to date. A team of astronomers [2] led by Jochen Greiner of the Max-Planck-Institut für extraterrestrische Physik (Germany) decided to make use of this unique opportunity to study the

  2. The Case of the Disappearing Spindle Burst

    Directory of Open Access Journals (Sweden)

    Alexandre Tiriac

    2016-01-01

    Full Text Available Sleep spindles are brief cortical oscillations at 10–15 Hz that occur predominantly during non-REM (quiet sleep in adult mammals and are thought to contribute to learning and memory. Spindle bursts are phenomenologically similar to sleep spindles, but they occur predominantly in early infancy and are triggered by peripheral sensory activity (e.g., by retinal waves; accordingly, spindle bursts are thought to organize neural networks in the developing brain and establish functional links with the sensory periphery. Whereas the spontaneous retinal waves that trigger spindle bursts in visual cortex are a transient feature of early development, the myoclonic twitches that drive spindle bursts in sensorimotor cortex persist into adulthood. Moreover, twitches—and their associated spindle bursts—occur exclusively during REM (active sleep. Curiously, despite the persistence of twitching into adulthood, twitch-related spindle bursts have not been reported in adult sensorimotor cortex. This raises the question of whether such spindle burst activity does not occur in adulthood or, alternatively, occurs but has yet to be discovered. If twitch-related spindle bursts do occur in adults, they could contribute to the calibration, maintenance, and repair of sensorimotor systems.

  3. 1974 Arizona P.A.C.E. participation.

    Science.gov (United States)

    Zabezensky, F

    1976-12-01

    Members of the Arizona State Society for Medical Technology were contacted to ascertain their knowledge of the P.A.C.E. program as well as to obtain release of the transcripts for those who participated during 1974. Observations regarding reported credits were noted. The Analysis of Variance test with Scheffe comparison was utilized to determine if any characteristic accounted for the difference in total continuing education hours reported. It was concluded that residence location, marital status, sex, age, degree level, length of membership in ASMT, years experience, employment extent, place of employment, and number of beds at place of employment had no significant effect on the total hours reported. A significant difference in total hours reported was noted for those individuals who reported either CEU or college credits. A significant difference was also noted in the total hours reported with respect to job description. PMID:998653

  4. PACE: A dynamic programming algorithm for hardware/software partitioning

    DEFF Research Database (Denmark)

    Knudsen, Peter Voigt; Madsen, Jan

    1996-01-01

    This paper presents the PACE partitioning algorithm which is used in the LYCOS co-synthesis system for partitioning control/dataflow graphs into hardware and software parts. The algorithm is a dynamic programming algorithm which solves both the problem of minimizing system execution time with a...... hardware area constraint and the problem of minimizing hardware area with a system execution time constraint. The target architecture consists of a single microprocessor and a single hardware chip (ASIC, FPGA, etc.) which are connected by a communication channel. The algorithm incorporates a realistic...... communication model and thus attempts to minimize communication overhead. The time-complexity of the algorithm is O(n2·𝒜) and the space-complexity is O(n·𝒜) where 𝒜 is the total area of the hardware chip and n the number of code fragments which may be placed in either hardware or software...

  5. Il cimitero è morto. Pace all’anima sua

    Directory of Open Access Journals (Sweden)

    Andrea Marcuccetti

    2012-06-01

    Full Text Available L’immagine che si ha di un cimitero è quella che deriva dal modello ottocentesco, per tanti anni rimasto matrice dei cimiteri attuali. Ha senso ancora oggi progettare cimiteri, in una società sempre più digitale e virtuale, dove il ricordo, la memoria sono sempre meno legati al luogo di sepoltura, dove le direttive napoleoniche risultano superate e non più rispondenti alla visione tecnologica del mondo in cui viviamo? È il momento di cominciare a ripensare il concetto stesso di cimitero, oltre la realtà che lo configura come un  luogo relegato in un recinto. Che i cimiteri stiano morendo è un dato di fatto. La loro decomposizione è già cominciata nelle grandi metropoli, impensabile ma inevitabile. Bisogna cominciare a farsene una ragione, com’è inteso oggi: il cimitero è morto. Pace all’anima sua.

  6. Seasonal Pacing - Match Importance Affects Activity in Professional Soccer

    Science.gov (United States)

    Link, Daniel; de Lorenzo, Michael F.

    2016-01-01

    This research explores the influence of match importance on player activity in professional soccer. Therefore, we used an observational approach and analyzed 1,211 matches of German Bundesliga and 2nd Bundesliga. The importance measurement employed is based on post season consequences of teams involved in a match. This means, if a match result could potentially influence the final rank, and this rank would lead to different consequences for a team, such as qualification for Champions League opposed to qualification for Europe League, then this match is classified as important; otherwise not. Activity was quantified by TOTAL DISTANCE COVERED, SPRINTS, FAST RUNS, DUELS, FOULS and ATTEMPTS. Running parameters were recorded using a semi-automatic optical tracking system, while technical variables were collected by professional data loggers. Based on our importance classification, low important matches occurred at the beginning of round 29. A two-way ANOVA indicates significantly increased FAST RUNS (+4%, d = 0.3), DUELS (+16%, d = 1.0) and FOULS (+36%, d = 1.2) in important matches compared to low important ones. For FAST RUNS and FOULS, this effect only exists in Bundesliga. A comparison of the two leagues show that TOTAL DISTANCE COVERED (+3%, d = 0.9), SPRINTS (+25%, d = 1.4) and FAST RUNS (+15%, d = 1.4) are higher compared to 2nd Bundesliga, whilst FOULS is less in Bundesliga (-7%, d = 0.3). No difference in player activity was found between matches at the beginning of a season (round 1–6) and at the end of a season (round 29–34). We conclude that match importance influences player activity in German professional soccer. The most reasonable explanation is a conscious or unconscious pacing strategy, motivated by preserving abilities or preventing injury. Since this tendency mainly exists in Bundesliga, this may suggest that more skilled players show a higher awareness for the need of pacing. PMID:27281051

  7. Specific Intensity for Peaking: Is Race Pace the Best Option?

    Directory of Open Access Journals (Sweden)

    Munoz

    2015-09-01

    Full Text Available Background The peaking period for endurance competition is characterized for a relative increase of the intensity of training, after a longer period of training relatively dominated by lower intensity and higher volume Objectives The present study was designed to compare physiological and 10 km performance effects of high intensity training (HIT versus race pace interval training (RP during peaking for competition in well-trained runners. Patients and Methods 13 athletes took part in the study, they were divided into two groups: HIT and RP. HIT performed short intervals at ~105% of the maximal aerobic velocity (MAV, while RP trained longer intervals at a speed of ~90% of the MAV (a speed approximating 10 km race pace. After 12 weeks of baseline training, the athletes trained for 6 weeks under one of the two peaking regimes. Subjects performed 10 km prior to and after the intervention period. The total load of training was matched between groups during the treatment phase. Subjects completed a graded treadmill running test until volitional exhaustion prior to each 10 km race. MAV was determined as the minimal velocity eliciting maximal oxygen consumption (VO2max. Results Both groups significantly improved their 10 km time (35 minutes 29 seconds ± 1 minutes 41 seconds vs 34 minutes 53 seconds ± 1 minutes 55 seconds, P 0.05. In contrast, running economy decreased significantly after HIT (210 ± 6 ml.Kg-1.km-1 vs 218 ± 9, P < 0.05. Conclusions A 6 week period of training at either 105% of MAV or 90% of MAV yielded similar performance gains in a 10km race performed at ~90% MAV. Therefore, the physiological impact of HIT training seems to be positive for VO2max but negative for running economy.

  8. Seasonal Pacing - Match Importance Affects Activity in Professional Soccer.

    Science.gov (United States)

    Link, Daniel; de Lorenzo, Michael F

    2016-01-01

    This research explores the influence of match importance on player activity in professional soccer. Therefore, we used an observational approach and analyzed 1,211 matches of German Bundesliga and 2nd Bundesliga. The importance measurement employed is based on post season consequences of teams involved in a match. This means, if a match result could potentially influence the final rank, and this rank would lead to different consequences for a team, such as qualification for Champions League opposed to qualification for Europe League, then this match is classified as important; otherwise not. Activity was quantified by TOTAL DISTANCE COVERED, SPRINTS, FAST RUNS, DUELS, FOULS and ATTEMPTS. Running parameters were recorded using a semi-automatic optical tracking system, while technical variables were collected by professional data loggers. Based on our importance classification, low important matches occurred at the beginning of round 29. A two-way ANOVA indicates significantly increased FAST RUNS (+4%, d = 0.3), DUELS (+16%, d = 1.0) and FOULS (+36%, d = 1.2) in important matches compared to low important ones. For FAST RUNS and FOULS, this effect only exists in Bundesliga. A comparison of the two leagues show that TOTAL DISTANCE COVERED (+3%, d = 0.9), SPRINTS (+25%, d = 1.4) and FAST RUNS (+15%, d = 1.4) are higher compared to 2nd Bundesliga, whilst FOULS is less in Bundesliga (-7%, d = 0.3). No difference in player activity was found between matches at the beginning of a season (round 1-6) and at the end of a season (round 29-34). We conclude that match importance influences player activity in German professional soccer. The most reasonable explanation is a conscious or unconscious pacing strategy, motivated by preserving abilities or preventing injury. Since this tendency mainly exists in Bundesliga, this may suggest that more skilled players show a higher awareness for the need of pacing. PMID:27281051

  9. Bursting neurons and ultrasound avoidance in crickets

    Directory of Open Access Journals (Sweden)

    Gary eMarsat

    2012-07-01

    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.

  10. Gamma-Ray Bursts: Jets and Energetics

    CERN Document Server

    Frail, D A

    2003-01-01

    The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.

  11. EXIST's Gamma-Ray Burst Sensitivity

    OpenAIRE

    Band, D. L.; Grindlay, J. E.; Hong, J.; Fishman, G.; Hartmann, D. H.; Garson III, A.; Krawczynski, H.; Barthelmy, S.; Gehrels, N.; Skinner, G.

    2007-01-01

    We use semi-analytic techniques to evaluate the burst sensitivity of designs for the EXIST hard X-ray survey mission. Applying these techniques to the mission design proposed for the Beyond Einstein program, we find that with its very large field-of-view and faint gamma-ray burst detection threshold, EXIST will detect and localize approximately two bursts per day, a large fraction of which may be at high redshift. We estimate that EXIST's maximum sensitivity will be ~4 times greater than that...

  12. The Arecibo Fast Radio Burst: Dense Circum-burst Medium

    CERN Document Server

    Kulkarni, S R; Neill, J D

    2015-01-01

    The nature of fast radio bursts (FRB) has been extensively debated. Here we investigate FRB121102, detected at Arecibo telescope and remarkable for its unusually large spectral index. After extensive study we conclude that the spectral index is caused by a nebula with free-free absorption. We find that putative nebula must lie beyond the Milky Way. We conclude that FRBs are of extra-galactic origin and that they arise in dense star-forming regions. The challenge with extra-galactic models is the the high volumetric rate of FRBs. This high rate allows us to eliminate all models of catastrophic stellar deaths. Hyper-giant flares from young magnetars emerge as the most likely progenitors. Some of the consequences are: (i) Intergalactic FRB models can be safely ignored. (ii) The rich ISM environment of young magnetars can result in significant contribution to DM, Rotation Measure (RM) and in some cases to significant free-free optical depth. (iii) The star-forming regions in the host galaxies can contribute signi...

  13. ESTIMATE OF BURSTING PRESSURE OF MILD STEEL PRESSURE VESSEL AND PRESENTATION OF BURSTING FORMULA

    Institute of Scientific and Technical Information of China (English)

    ZHENG Chuanxiang

    2006-01-01

    In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235(Gr.D) and 20R(1020) are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness.Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.

  14. Burst suppression probability algorithms: state-space methods for tracking EEG burst suppression

    OpenAIRE

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

    2013-01-01

    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 ident...

  15. Self-Paced Advanced Individual Training (AIT) and Duty Assignment Procedures.

    Science.gov (United States)

    Hunter, Harold; Wagner, Harold

    A study was made to (a) describe how self-paced Military Occupational Specialty (MOS) training affects the Army assignment system; (b) identify ways the existing assignment system can accommodate individualized instruction; and (c) suggest modifications to the assignment system to provide better integration of self-paced training with assignment…

  16. PACE: A test bed for the dynamics and control of flexible multibody systems

    Science.gov (United States)

    Kwak, Moon K.; Smith, Monty J.; Das, Alok

    1993-01-01

    The Phillips Laboratory at Edwards AFB has constructed a test bed for the validation and comparison of modeling and control theories for the dynamics and control of flexible multibody systems. This project is called the Planar Articulating Controls Experiment (PACE). This paper presents the experimental apparatus for PACE and the problem formulation. An in-depth analysis on DC motor dynamics was also performed.

  17. TEE-guided left ventricular epicardial pacing lead placement for cardiac resynchronization therapy

    Directory of Open Access Journals (Sweden)

    Rajesh Chand Arya

    2012-01-01

    Full Text Available Biventricular pacing has demonstrated improvement in cardiac functions in treating congestive cardiac failure patients. Recent trials have proven the clinical and functional benefits of cardiac resynchronization therapy in severe heart failure and intraventricular cardiac delays, mainly left bundle branch block. Biventricular pacing improves the exercise tolerance, quality of life, systolic heart function, reduces hospitalization and slows progression of the disease. A 54-year-old lady, a known case of dilated cardiomyopathy, was on biventricular pacing since 2 years. She presented in emergency with sudden deterioration of dyspnea to NYHA class III/IV. When investigated, the coronary sinus lead was found displaced; thus, left ventricle (LV was not getting paced. After multiple failures to reposition the coronary sinus lead, it was decided to surgically place the epicardial lead for LV pacing under general anesthesia. Lateral thoracotomy was done and LV pacing lead was placed at different sites with simultaneous monitoring of cardiac output (CO and stroke volume (SV by transesophageal echocardiography (TEE. Baseline CO and SV were 1.9 l/min and 19.48 ml respectively and increased at different sites of pacing at LV, the best CO and SV were 4.2 l/min and 42.39 ml respectively on lateral surface. Intraoperative TEE can calculate beat to beat stroke volume and thus CO and helps to choose optimal site for placement of epicardial pacing lead.

  18. Directivity of low-frequency solar type 3 radio bursts

    International Nuclear Information System (INIS)

    The occurrence rate of type 3 solar bursts in the frequency range 4.9 MHz to 30 kHz was analyzed as a function of burst intensity and burst arrival direction. Results show that the occurrence rate of bursts falls off with increasing flux and the distribution of burst arrival directions at each frequency shows a significantly larger number of bursts observed west of the earth--sun line than east of it. This western excess in occurrence rate appears to be correlated with the direction of the average interplanetary magnetic field, and is interpreted as beaming of the observed burst radiation along the magnetic field direction

  19. Long Burst Error Correcting Codes Project

    Data.gov (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...

  20. Relativistic effects in gamma-ray bursts

    International Nuclear Information System (INIS)

    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)

  1. FRBCAT: The Fast Radio Burst Catalogue

    CERN Document Server

    Petroff, E; Jameson, A; Keane, E F; Bailes, M; Kramer, M; Morello, V; Tabbara, D; van Straten, W

    2016-01-01

    Here we present a catalogue of known Fast Radio Burst (FRB) sources in the form of an online catalogue, FRBCAT. The catalogue includes information about the instrumentation used for the observations for each detected burst, the measured quantities from each observation, and model-dependent quantities derived from observed quantities. To aid in consistent comparisons of burst properties such as width and signal-to-noise ratios we have reprocessed all the bursts for which we have access to the raw data, with software which we make available. The originally derived properties are also listed for comparison. The catalogue is hosted online as a MySQL database which can also be downloaded in tabular or plain text format for off-line use. This database will be maintained for use by the community for studies of the FRB population as it grows.

  2. Bursts of intermediate ions in atmospheric air

    Science.gov (United States)

    Hõrrak, U.; Salm, J.; Tammet, H.

    1998-06-01

    The mobility spectrum of air ions has been measured at Tahkuse Observatory in Estonia for several years. The average concentration of intermediate ions with mobilities of 0.05-0.5 cm2 V-1 s-1 in atmospheric air is about 50 cm-3. On the level of this low background, high concentration bursts of intermediate air ions occur occasionally. A burst can be followed by subsequent evolution of intermediate ions into larger ones. To explain the bursts of intermediate air ions, two hypotheses can be advanced: (1)A burst of neutral particles occurs due to homogeneous nucleation, and the particles are charged by the attachment of cluster ions. (2) The cluster ions grow by ion-induced nucleation in proper environmental conditions.

  3. Burst Fragmentation Model Based on Sequential Burst Allocation Algorithm for Mobile WiMAX

    Directory of Open Access Journals (Sweden)

    Zaid G. Ali

    2013-07-01

    Full Text Available the downlink Bandwidth resources of WiMAX are allocated by the burst allocation algorithm. The algorithm is responsible for calculating the appropriate location of a number of the smallest unit of bandwidth which is called the slot for all users within the downlink subframe in the form of bursts. Resource wastage in the form of unused and unallocated slots is a real common problem accompanies resource management in the burst allocation algorithms. This paper investigates the Sequential Burst Allocation (SBA that based on sequential slot allocation and burst fragmentation. An analytical model of frame utilization has been derived. Moreover, this paper presents criteria of burst fragmentation and investigates the effect of burst fragmentation to the allocation efficiency. It has been observed from the results that the SBA algorithm outperforms the Standard (ST algorithm in term of number of users and resource wastage reduction per frame. The research results illustrates that burst fragmentation can enhance the proportion of frame utilization with minor effect to the overhead size. As well as, the results are useful to be a heuristic guide line for MAC layer scheduler to decide the best burst size that can be used.

  4. Design of assembly control algorithm based on burst-size feedback for optical burst switching network

    Institute of Scientific and Technical Information of China (English)

    Minglei Fu; Zichun Le

    2009-01-01

    A novel assembly control algorithm named burst-size feedback adaptive assembly period(BFAAP)is proposed.The major difference between BFAAP and other similar adaptive assembly algorithms is that the control curve of BFAAP is dynamically adjusted according to the feedback of outgoing burst size.BFAAP is compared with two typical algorithms fixed assembly period(FAP)aild min-burst length max assembly period(MBMAP)in simulation in terms of burst size distribution and assembly period.Moreover,the transmission control protocol(TCP)performance over BFAAP is also considered and simulated.

  5. A Burst-by-Burst Adaptive Joint-Detection Based CDMA Speech Transceiver

    OpenAIRE

    How, HT; Liew, TH; Kuan, EL; Hanzo, L.

    2001-01-01

    A burst-by-burst adaptive speech transceiver is proposed, which can drop its source coding rate and speech quality under transceiver control in order to invoke a more error resilient modem mode amongst less favourable channel conditions. The novel, high-quality, Adaptive Multi-Rate (AMR) speech codec [5], operated at bit rates of 4.75 and 10.2 kbps and combined with sourcesensitivity-matched Redundant Residue Number Systems (RRNS) based channel codes. Burst-by-burst adaptive Joint-Detection b...

  6. Research on Electrical Remodeling After Short Term Pacing in Canine Model

    Institute of Scientific and Technical Information of China (English)

    Kebbati A Hafid; Huang Congxin; Wang Xi; Zhao Qingyan

    2007-01-01

    Objectives To evaluate the changes in atrial effective refractory period (AERP) proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage (RAA) and to relate these changes to the ability to induce AF. Methods Twelve mongrel dogs in normal sinus rhythm were paced from the superior left PVs or RAA at 500 bpm for 4 hours. Electrophysiologic studies conducted to determine changes in AERP, dispersion and rhythm. Ionic currents were studies with the patch clamp technique in single PVs myocytes in sham operated dogs and compared with those from PVs pacing and RAA pacing groups. Results The presence of rapid atrial pacing was associated with a marked shortening in AERP in both PVs and RAA pacing group with a marked increase of AERP dispersion in PVs pacing. Both L-type calcium current (ICa, L) and the transient outward current (Ito)were reduced in both groups with an increased significance in PVs pacing group. The density of ICa-L WaS decreased significantly from ( - 6.03 ± 0.63 ) pA/pF in the control group to ( -3.21±0.34) pA/pF in PVs pacing group and ( - 4,75 ± 0.41 ) pA/pF in RAA pacing group (n = 6, P<0.05) while the density of Ito was decreased significantly from (8.45±0.71 ) pA/pF in the control group to (5.21 ±0.763 ) pA/pF in PVs pacing group and (6,84 ± 0.69) pA/pF in RAA pacing group (n = 6, P<0.05). Conclusions Our findings provide likely ionic mechanisms of shortened repolarization in induced atrial tachycardia with a decrease in Ica,L and Ito current densities which is the likely mechanism for a decrease in Action potential duration (APD) rate adaptation in the canine rapid pacing model more pronounced in PVs pacing group underlying the crucial role of PVs in initiating AF.

  7. Optimal Codes for the Burst Erasure Channel

    Science.gov (United States)

    Hamkins, Jon

    2010-01-01

    Deep space communications over noisy channels lead to certain packets that are not decodable. These packets leave gaps, or bursts of erasures, in the data stream. Burst erasure correcting codes overcome this problem. These are forward erasure correcting codes that allow one to recover the missing gaps of data. Much of the recent work on this topic concentrated on Low-Density Parity-Check (LDPC) codes. These are more complicated to encode and decode than Single Parity Check (SPC) codes or Reed-Solomon (RS) codes, and so far have not been able to achieve the theoretical limit for burst erasure protection. A block interleaved maximum distance separable (MDS) code (e.g., an SPC or RS code) offers near-optimal burst erasure protection, in the sense that no other scheme of equal total transmission length and code rate could improve the guaranteed correctible burst erasure length by more than one symbol. The optimality does not depend on the length of the code, i.e., a short MDS code block interleaved to a given length would perform as well as a longer MDS code interleaved to the same overall length. As a result, this approach offers lower decoding complexity with better burst erasure protection compared to other recent designs for the burst erasure channel (e.g., LDPC codes). A limitation of the design is its lack of robustness to channels that have impairments other than burst erasures (e.g., additive white Gaussian noise), making its application best suited for correcting data erasures in layers above the physical layer. The efficiency of a burst erasure code is the length of its burst erasure correction capability divided by the theoretical upper limit on this length. The inefficiency is one minus the efficiency. The illustration compares the inefficiency of interleaved RS codes to Quasi-Cyclic (QC) LDPC codes, Euclidean Geometry (EG) LDPC codes, extended Irregular Repeat Accumulate (eIRA) codes, array codes, and random LDPC codes previously proposed for burst erasure

  8. Temporary neonatal atrial pacing through the umbilical venous route: A novel technique

    Directory of Open Access Journals (Sweden)

    Hiren N Doshi

    2011-01-01

    Full Text Available Atrial pacing in the neonate is rarely done due to constraints of equipment, technical knowhow, and risk of complications. We describe a novel method of atrial pacing in the new born using equipment readily available in any intensive care unit. Atrial pacing can be achieved using an adult bipolar pacing wire directly introduced through the umbilical venous route. We have used this method in 5 neonates, and achieved atrial capture in 4 patients. Temporary atrial pacing is a therapeutic option in a few neonatal arrhythmias, such as atrial flutter, a few types of re-entrant tachycardias, such as accessory pathway mediated tachycardia and junctional reciprocating tachycardia, and has a limited role in cardiopulmonary resuscitation where sinoatrial node dysfunction is suspected.

  9. Black Hole Lensing and Wave Bursts

    CERN Document Server

    Gogberashvili, Merab

    2016-01-01

    It is shown that close to a black hole horizon wave equations have real-valued exponentially time-dependent solutions and to investigate strong gravitational lensing we need to introduce an effective negative cosmological constant between the Schwarzschild and photon spheres. Then exponentially amplified reflected waves from this effective AdS space could explain properties of some gamma ray bursts, fast radio bursts and gravitational waves.

  10. 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)

    2015-12-17

    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%.

  11. Cosmological parametrization of $\\gamma$ ray burst models

    CERN Document Server

    Linder, E V

    1996-01-01

    Using three parametrizations of the gamma ray burst count data comparison is made to cosmological source models. While simple models can fit and faint end slope constraints, the addition of a logarithmic count range variable describing the curvature of the counts shows that models with no evolution or evolution power law in redshift with index less than 10 fail to satisfy simultaneously all three descriptors of the burst data. The cosmological source density that would be required for a fit is illustrated.

  12. Autaptic Connections Shift Network Excitability and Bursting

    OpenAIRE

    Wiles, Laura; Gu, Shi; Pasqualetti, Fabio; Bassett, Danielle S.; Meaney, David F.

    2016-01-01

    Network architecture forms a critical constraint on neuronal function. Here we examine the role of structural autapses, when a neuron synapses onto itself, in driving network-wide bursting behavior. Using a simple spiking model of neuronal activity, we study how autaptic connections affect activity patterns, and evaluate if neuronal degree or controllability are significant factors that affect changes in bursting from these autaptic connections. We observed that adding increasing numbers of a...

  13. Supernovae and gamma-ray bursts connection

    Science.gov (United States)

    Valle, Massimo Della

    2015-12-01

    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%.

  14. Neutrinos from Gamma Ray Bursts

    CERN Document Server

    Mannheim, K

    2000-01-01

    The observed fluxes of cosmic rays and gamma rays are used to infer the maximum allowed high-energy neutrino flux allowed for Gamma Ray Bursts (GRBs), following Mannheim, Protheroe, and Rachen (2000). It is shown that if GRBs produce the ultrahigh-energy cosmic rays, they should contribute (a) at least 10% of the extragalactic gamma ray background between 3 MeV and 30 GeV, contrary to their observed energy flux which is only a minute fraction of this flux, and (b) a cumulative neutrino flux a factor of 20 below the AMANDA (Neutrino 2000) limit on isotropic neutrinos. This could have two implications, either GRBs do not produce the ultrahigh energy cosmic rays or that the GRBs are strongly beamed and emit most of their power at energies well above 100 GeV implausibly increasing the energy requirements, but consistent with the marginal detections of a few low-redshift GRBs by MILAGRITO, HEGRA-AIROBICC, and the Tibet-Array. All crucial measurements to test the models will be available in the next few years. Thes...

  15. Gamma-ray Burst Cosmology

    CERN Document Server

    Wang, F Y; Liang, E W

    2015-01-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it...

  16. Meteor burst communications improvement study

    Science.gov (United States)

    Peterson, David

    1993-07-01

    Two identical Meteor Burst Radio Terminals were developed, fabricated, and delivered to the Air Force. Each is controlled by a PC computer in a menu driven manner. The mode of operation is full duplex. The RF frequency range is 40 to 60 MHz with tuning increments of 25 KHz. Data rates are 4, 8, 16, 32, 64, 128, 256, and 512 kbps. Modulation is coherent Binary Phase Shift Keying (BPSK) and incoherent Differential Phase Shift Keying (DPSK). Protocol includes Automatic Repeat Request (ARQ) with source and destination addressing, message number, start of message, and end of message. Messages are packetized, and Reed Solomon (R-S) coding is an option. The ARQ is under the control of a Cyclic Redundancy Check Code (CRCC) which detects binary errors within each packet. The terminal is intended to increase meteor trail availability and data throughput by several orders of magnitude--by operating with new antennas that provide much higher gains without sacrificing meteor trail acquisition performance.

  17. Propofol and sevoflurane induce distinct burst suppression patterns in rats

    OpenAIRE

    Kenny, Jonathan D.; Westover, M. Brandon; Ching, ShiNung; Brown, Emery N.; Solt, Ken

    2014-01-01

    Burst suppression is an EEG pattern characterized by alternating periods of high-amplitude activity (bursts) and relatively low amplitude activity (suppressions). Burst suppression can arise from several different pathological conditions, as well as from general anesthesia. Here we review current algorithms that are used to quantify burst suppression, its various etiologies, and possible underlying mechanisms. We then review clinical applications of anesthetic-induced burst suppression. Final...

  18. Effects of right atrial and ventricular DDD pacing on cardiac function and ventricular contraction synchrony

    Institute of Scientific and Technical Information of China (English)

    支力大; 华伟; 张澍; 史蓉芳; 王方正; 陈新

    2004-01-01

    Background Right ventricular apical pacing has been reported to reduce cardiac performance. But there are few reports on the effects of dual chamber (DDD) pacing on cardiac function compared to sinus rhythm. In this study, we evaluated the effects of right atrial and ventricular DDD pacing on cardiac function and ventricular contraction synchrony using equilibrium radionuclide angiography.Methods Ten patients implanted with a right atrial and ventricular DDD pacemaker underwent equilibrium radionuclide angiography. The scintigraphic data were obtained during sinus rhythm and pacing rhythm. Cardiac function parameters were obtained semimanually. Phase analysis was used to study the ventricular activation sequence and ventricular synchrony.Results The left ventricular 1/3 ejection fraction decreased significantly during pacing compared with that during sinus rhythm[(23.4 ±6.1)% vs(27.7 ±4.5)%, P =0.01]. Regional ejection fraction also decreased during pacing, although the difference was not statistically significant. Phase analysis showed that the right ventricle was activated earlier than the left ventricle during pacing, and that the phase shift was significantly greater during pacing than that during sinus rhythm[64.13°±16.80° vs 52.88°± 9.26°, P =0.007]. The activation of both ventricles occurred simultaneously during sinus rhythm, with the activation sequence from proximal septum or base of left ventricle to apex. The earliest activation during pacing occurred at the right ventricular apex, and subsequently spread to the base and left ventricle.Conclusion Right atrial and ventricular DDD pacing impairs left ventricular systolic function and ventricular synchrony.

  19. Comparison of permanent left ventricular and biventricular pacing in patients with heart failure and chronic atrial fibrillation: prospective haemodynamic study

    OpenAIRE

    Garrigue, S; Bordachar, P.; Reuter, S.; Jaïs, P.; Kobeissi, A; Gaggini, G; Haïssaguerre, M; Clementy, J

    2002-01-01

    Objective: To compare clinical and haemodynamic variables between left ventricular and biventricular pacing in patients with severe heart failure; and to analyse haemodynamic changes during daily life and maximum exercise during chronic left ventricular and biventricular pacing.

  20. Observation of blood B-type natriuretic peptide level changes in different periods and different cardiac pacing modes

    Institute of Scientific and Technical Information of China (English)

    WANG Ru-xing; LI Xiao-rong; JIANG Wen-ping; LIU Zhi-hua; YANG Xiang-jun; XIAO Chun-hui; SHAO Li-zheng; ZHU Jian-qiu

    2005-01-01

    @@ In recent years, the indications of cardiac pacing have extended continuously with the rapid development of pacing technique. Pacemaker treatment has not only limited in arrhythmias of bradycardia and the number of pacemaker treatment has increased year by year.

  1. Temporary pace makers implantation: do we need fluoroscopy

    International Nuclear Information System (INIS)

    Temporary pace maker (TPM) implantation is done mostly in emergency with assistance of fluoroscopy. Fluoroscopy has various constrains which may delay the procedure at different occasion. We are going to share our experience in TPM implantation without fluoroscopy from internal jugular vein. Methods: The case series study was conducted in Hayatabad Medical complex Peshawar from January 2011 to November 2011. Internal jugular vein was cannulated with 6 French sheaths in the supra-clavicular region with modified Seldinger technique. TPM wire connected to the TPM device and advanced in the sheath to the right ventricle. Position was confirmed from captured beat on monitor. There was no need of repositioning and lead remains stable. Results: Total 122 TPM leads were implanted in the study period. All patients were implanted from internal jugular vein. There were 71 male and 51 female patients. Among these patients 55 were in hemodynamically unstable state. The average time of implantation was less than 10 minutes. There was failure in one case. So the overall success rate was 99.180%. Conclusion: TPM implantation from the internal jugular vein even without fluoroscopy is safe, less time consuming and convenient. (author)

  2. Bioelectromagnetic localization of a pacing catheter in the heart

    International Nuclear Information System (INIS)

    The accuracy of localizing source currents within the human heart by non-invasive magneto- and electrocardiographic methods was investigated in 10 patients. A non-magnetic stimulation catheter inside the heart served as a reference current source. Biplane fluoroscopic imaging with lead ball markers was used to record the catheter position. Simultaneous multichannel magnetocardiographic (MCG) and body surface potential mapping (BSPM) recordings were performed during catheter pacing. Equivalent current dipole localizations were computed from MCG and BSPM data, employing standard and patient-specific boundary element torso models. Using individual models with the lungs included, the average MCG localization error was 7±3 mm, whereas the average BSPM localization error was 25±4 mm. In the simplified case of a single homogeneous standard torso model, an average error of 9±3 mm was obtained from MCG recordings. The MCG localization accuracies obtained in this study imply that the capability of multichannel MCG to locate dipolar sources is sufficient for clinical purposes, even without constructing individual torso models from x-ray or from magnetic resonance images. (author)

  3. Bioelectromagnetic localization of a pacing catheter in the heart

    Science.gov (United States)

    Pesola, K.; Nenonen, J.; Fenici, R.; Lötjönen, J.; Mäkijärvi, M.; Fenici, P.; Korhonen, P.; Lauerma, K.; Valkonen, M.; Toivonen, L.; Katila, T.

    1999-10-01

    The accuracy of localizing source currents within the human heart by non-invasive magneto- and electrocardiographic methods was investigated in 10 patients. A non-magnetic stimulation catheter inside the heart served as a reference current source. Biplane fluoroscopic imaging with lead ball markers was used to record the catheter position. Simultaneous multichannel magnetocardiographic (MCG) and body surface potential mapping (BSPM) recordings were performed during catheter pacing. Equivalent current dipole localizations were computed from MCG and BSPM data, employing standard and patient-specific boundary element torso models. Using individual models with the lungs included, the average MCG localization error was 7±3 mm, whereas the average BSPM localization error was 25±4 mm. In the simplified case of a single homogeneous standard torso model, an average error of 9±3 mm was obtained from MCG recordings. The MCG localization accuracies obtained in this study imply that the capability of multichannel MCG to locate dipolar sources is sufficient for clinical purposes, even without constructing individual torso models from x-ray or from magnetic resonance images.

  4. Council sets pace for '82-'84 action

    Science.gov (United States)

    The December 1982 meeting of the AGU Council, the first in the 1982-1984 biennium, has set a new pace. It is the first Council Meeting in the memory of any of those participating at which every Council member was present in person. This record attests to the importance Section presidents and president-elects place on their responsibilities as representatives of their sections and as members of what in effect is AGU's Board of Directors; and it is a further tribute to the value they place on AGU.Both the Council and the AGU Executive Committee held their meetings on December 9, 1982, during the Fall Meeting in San Francisco. President Van Allen, President-elect Drake, General Secretary Meredith, Foreign Secretary Kisslinger, and Executive Director Spilhaus constitute the Executive Committee. The full Council includes the Executive Committee and the President and President-elect of each Section. At its meetings the Council usually addresses administrative matters such as budgeting, examines existing operations, and considers proposed new programs. The Executive Committee acts on behalf of the Council between Council meetings; it is specifically charged with approving Chapman conferences, the cosponsorship of other meetings, and several other largely administrative actions.

  5. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  6. A biomechanical study on burst mechanisms of plant fruit: stress analysis of pericarps before bursting.

    Science.gov (United States)

    Endo, Yasuhiro; Sakamoto, Jiro; Kashiwano, Yuki; Yokota, Hideo; Nakamura, Sakiko; Kinoshita, Eichiro

    2010-10-01

    Bursting of fruit is a very interesting biomechanical phenomenon because its mechanism is directly related to the plant's reproduction. A plant that produces fruit that bursts powerfully and spreads the seeds widely has the advantage of reproduction without relying on other mechanisms such as transportation of fruit by insects. The structures of many types of fruit have likely been optimized by evolution, although the structure itself appears rather simplistic. Strain energy is stored in each pericarp because of growth deformation, swelling or desiccation just before bursting. Throughout these changes, the mechanical stress of the pericarps is at equilibrium. At the instant of bursting, the stored strain energy is released very rapidly. Quick and wide motion of the pericarps in a certain direction is advantageous for throwing the seed a long distance. The motion and deformation of bursting pericarps depend on their tissue structure and mechanical stress condition just before the burst. We tracked the bursting motion by using a high-speed camera. Then we calculated the pre-burst stress generated in a pericarp of Impatiens by using the finite-element method. The boundary condition obtained by experiments using a high-speed video camera is given, and the stress was calculated using reverse deformation analysis. The stress distribution of the pericarp is effective in causing the pericarp motion to throw the seeds far away. PMID:20696416

  7. 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

    2009-01-01

    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.

  8. The Cosmic Gamma-Ray Bursts

    Science.gov (United States)

    Djorgovski, S. G.; Frail, D. A.; Kulkarni, S. R.; Sari, R.; Bloom, J. S.; Galama, T. J.; Harrison, F. A.; Price, P. A.; Fox, D.; Reichart, D. E.; Yost, S.; Berger, E.; Diercks, A.; Goodrich, R.; Chaffee, F.

    2002-12-01

    Cosmic γ-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean γ-ray energies after the beaming corrections are ~ 1051 erg. Bursts are associated with faint ( ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host galaxies span a range of luminosities and morphologies, but appear to be broadly typical for the normal, actively star-forming galaxy populations at comparable redshifts and magnitudes. Some of the challenges for the future include: the nature of the short bursts and possibly other types of bursts and transients; use of GRBs to probe the obscured star formation in the universe, and possibly as probes of the very early universe; and their detection as sources of high-energy particles and gravitational waves.

  9. Cardiomyopathy induced by artificial cardiac pacing: myth or reality sustained by evidence?

    Directory of Open Access Journals (Sweden)

    Andrés Di Leoni Ferrari

    2014-09-01

    Full Text Available 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.

  10. Pacing-induced congenital heart defects assessed by OCT (Conference Presentation)

    Science.gov (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.

    2016-03-01

    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 develop into abnormal valves and septa. Our model produces similar phenotypes as found in our fetal alcohol syndrome and velo-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.

  11. An Intelligent Segmented Burst Assembly Mechanism in Optical Burst Switching Networks

    Institute of Scientific and Technical Information of China (English)

    XIE Yi-Yuan; ZHANG Jian-Guo

    2008-01-01

    We focus on the burst assembly mechanism and propose a new intelligent method in which the burst is assembled from several internet protocol (IP) packets in which the number of IP packets is changed according to the traffic load and the burst is segmented into several parts, called the ISOBS mechanism. The average burst assembly time of the ISOBS mechanism decreases as compared with the fixed-assembly-time and fixed-assembly-time-and-length mechanisms. The loss ratio decreases 50% as compared with the general optical burst switching (OBS) mechanism. The last segment can carry high quality of service (QOS) information. We can achieve that the loss ratio of the last segment is almost zero when the traffic load is less than 0.05. When the traffic load is 0.9, the loss ratio of the last segment is 0.0041. The ISOBS can support to transmit different QOS data.

  12. An Intelligent Segmented Burst Assembly Mechanism in Optical Burst Switching Networks

    International Nuclear Information System (INIS)

    We focus on the burst assembly mechanism and propose a new intelligent method in which the burst is assembled from several internet protocol (IP) packets in which the number of IP packets is changed according to the traffic load and the burst is segmented into several parts, called the ISOBS mechanism. The average burst assembly time of the ISOBS mechanism decreases as compared with the fixed-assembly-time and fixed-assembly-time-and-length mechanisms. The loss ratio decreases 50% as compared with the general optical burst switching (OBS) mechanism. The last segment can carry high quality of service (QOS) information. We can achieve that the loss ratio of the last segment is almost zero when the traffic load is less than 0.05. When the traffic load is 0.9, the loss ratio of the last segment is 0.0041. The ISOBS can support to transmit different QOS data. (fundamental areas of phenomenology (including applications))

  13. QKD-Based Secured Burst Integrity Design for Optical Burst Switched Networks

    Science.gov (United States)

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

    2016-03-01

    The field of optical transmission has undergone numerous advancements and is still being researched mainly due to the fact that optical data transmission can be done at enormous speeds. It is quite evident that people prefer optical communication when it comes to large amount of data involving its transmission. The concept of switching in networks has matured enormously with several researches, architecture to implement and methods starting with Optical circuit switching to Optical Burst Switching. Optical burst switching is regarded as viable solution for switching bursts over networks but has several security vulnerabilities. However, this work exploited the security issues associated with Optical Burst Switching with respect to integrity of burst. This proposed Quantum Key based Secure Hash Algorithm (QKBSHA-512) with enhanced compression function design provides better avalanche effect over the conventional integrity algorithms.

  14. Factors Affecting the Study Pace of First-Year Law Students: In Search of Study Counselling Tools

    Science.gov (United States)

    Haarala-Muhonen, Anne; Ruohoniemi, Mirja; Lindblom-Ylanne, Sari

    2011-01-01

    This study explores factors affecting the study pace of law students during their first academic year. The participants comprised two student groups: those whose number of study credits were the lowest and highest. Altogether, 25 students (11 with a slow and 14 with a fast study pace) were interviewed. The factors affecting study pace mentioned by…

  15. Assessment of Ventricular Dissynchrony in Right Ventricular Single Chamber Pacing using Echocardiografic Parameters

    Directory of Open Access Journals (Sweden)

    Vita I

    2014-04-01

    Full Text Available Background: Right ventricular apical pacing has been used since the early years of pace-makers, despite the fact that it determined nonphysiological ventricular depolarization. As medical technologies developed, septal lead implantation became feasible, in order to outrun the above mentioned inconveniences. The question whether the apical or septal lead position is better still gives rise to a lot of controversies. Different echocardiographic parameters are currently used to assess the impact of specific sites of stimulation on ventricular function. The aim of the study was to determine which of the followed synchronicity parameters varied significantly during apical stimulation, compared to septal stimulation in patients requiring single chamber pacing.

  16. Ventilation patterns mimicking COPD in patients with diaphragmatic pacing for Ondine's curse

    International Nuclear Information System (INIS)

    Ventilation was studied with 133Xe in 18 patients with central hypoventilation (Ondine's Curse) in whom diaphragmatic pacers were implanted. Three distinct patterns emerged: Type I, improvement in ventilation on the paced side (11 of 18 patients); Type II, improvement on both the paced and unpaced side (4 of 18); and Type III, no improvement (3 of 18). With the pacer off, many of these patients have patterns that mimic chronic obstructive pulmonary disease and that revert to normal with pacing. This retention, clearly reversible, cannot reflect permanent airways or airspace disease

  17. Successful treatment with biventricular pacing in a patient with hypertrophic obstructive cardiomyopathy

    Institute of Scientific and Technical Information of China (English)

    HE Ji-qiang; JIANG Teng-yong; WANG Yun-long; WANG Yan; L(U) Shu-zheng

    2011-01-01

    We report the effects of biventricular pacing in a patient with hypertrophic obstructive cardiomyopathy (HOCM) refractory to medical therapy. A 58-year-old man with HOCM had suffered from dyspnea,chest pain and palpitation for 5 years. Cardiac catheterization showed a left ventricular outflow tract (LVOT) gradient of 80 mmHg. He refused septal myomectomy and the septal ablation was not available. Based on intraoperative pressure measurements,he was implanted with biventricular pacing and LVOT gradient decreased to 10 mmHg. During the follow-up period of 6 months, the patient's symptoms were markedly improved. Biventricular pacing may be an alternative therapy for patients with HOCM.

  18. Sources of type III solar microwave bursts

    Science.gov (United States)

    Zhdanov, Dmitriy; Lesovoi, Sergey; Tokhchukova, Susanna

    2016-06-01

    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 extreme UV data, made it possible to localize sources of III type microwave drift bursts in August 10, 2011 event within the entire frequency band of burst occurrences, 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 source sizes at other frequencies.

  19. Diagnostics From Three Rising Submillimeter Bursts

    CERN Document Server

    Zhou, Ai-Hua; Wang, Xin-Dong

    2015-01-01

    In the paper we investigate three novel rising submillimeter (THz) bursts occurred sequentially in a super-Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu/GHz (corresponding spectral index $\\alpha$ of 1.6) for the THz spectral components of 2003 October 28 and November 4 bursts, while it can attain values of 235 sfu/GHz ($\\alpha$=4.8) for 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of high relativistic electrons with a low-energy cutoff of 1 MeV , while 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 that in microwave (MW) one. It is interesting that the THz source radius decreased by 20--50$\\%$ during the decay phase for the three events, but the MW one increased by 28$\\%$ for the 2003 Novemb...

  20. The Fermi Gamma-Ray Burst Monitor

    CERN Document Server

    Meegan, Charles; Bhat, P N; Bissaldi, Elisabetta; Briggs, Michael S; Connaughton, Valerie; Diehl, Roland; Fishman, Gerald; Greiner, Jochen; Hoover, Andrew S; van der Horst, Alexander J; von Kienlin, Andreas; Kippen, R Marc; Kouveliotou, Chryssa; McBreen, Sheila; Paciesas, W S; Preece, Robert; Steinle, Helmut; Wallace, Mark S; Wilson, Robert B; Wilson-Hodge, Colleen

    2009-01-01

    The Gamma-Ray Burst Monitor (GBM) will significantly augment the science return from the Fermi Observatory in the study of Gamma-Ray Bursts (GRBs). The primary objective of GBM is to extend the energy range over which bursts are observed downward from the energy range of the Large Area Telescope (LAT) on Fermi into the hard X-ray range where extensive previous data exist. A secondary objective is to compute burst locations on-board to allow re-orientiong the spacecraft so that the LAT can observe delayed emission from bright bursts. GBM uses an array of twelve sodium iodide scintillators and two bismuth germanate scintillators to detect gamma rays from ~8 keV to ~40 MeV over the full unocculted sky. The on-board trigger threshold is ~0.7 photons/cm2/s (50-300 keV, 1 s peak). GBM generates on-board triggers for ~250 GRBs per year.

  1. Swift: A Gamma Ray Bursts Explorer

    Science.gov (United States)

    Gehrels, Neil

    2003-01-01

    Swift is a NASA gamma-ray burst MIDEX mission that is in development for launch in December 2003. It is a multiwavelength transient observatory for GRB astronomy. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. It will also.perform a survey of the hard X-ray sky to a sensitivity level of -1 mCrab. A wide-field camera will detect more than a hundred GRBs per year to 5 times fainter than BATSE. Sensitive narrow-field X-ray and UV/optical telescopes will be pointed at the burst location in 20 to 70 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approximately 0.5 square meter) CdZnTe detector array. The hardware is currently in final stages of fabrication and initial stages of integration and test. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift.

  2. The Cosmic Gamma-Ray Bursts

    CERN Document Server

    Djorgovski, S G; Kulkarni, S R; Sari, R; Bloom, J S; Galama, T J; Harrison, F A; Price, P A; Fox, D; Reichart, D; Yost, S; Berger, E; Diercks, A H; Goodrich, R; Chaffee, F H

    2001-01-01

    Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean gamma-ray energies after the beaming corrections are ~ 10^51 erg. Bursts are associated with faint ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host gal...

  3. X-ray bursts observed with JEM-X

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Chenevez, Jérôme; Lund, Niels; Budtz-Jørgensen, Carl; Westergaard, Niels Jørgen Stenfeldt

    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....

  4. X-ray bursts observed with JEM-X

    DEFF Research Database (Denmark)

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

    2006-01-01

    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. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    Science.gov (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.

    2009-01-01

    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 ages, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles. 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 warming. 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 today and atmospheric CO 2 concentration was as high as ???400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model 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 melt under conditions of elevated CO2. ??2009 Macmillan Publishers Limited. All rights reserved.

  6. High sensitivity neutron bursts detecting system

    International Nuclear Information System (INIS)

    Technique and instrumentation to detect multiplicity of fast neutrons, emitted in sharp bursts, has been developed. A bank of 16 BF3 detectors, in an appropriate thermalising assembly, efficiency ∼ 16%, is used to detect neutron bursts. The output from this setup, through appropriate electronics, is divided into two paths. The first is directly connected to a computer controlled scalar. The second is connected to another similar scalar through a delay time unit (DTU). The DTU design is such that once it is triggered by a count pulse than it does not allow any counts to be recorded for a fixed dead time set at ∼ 100 μs. The difference in counts recorded directly and through DTU gives the total number of neutrons produced in bursts. This setup is being used to study lattice cracking, anomalous effects in solid deuterium systems and various reactor physics experiments. (author). 3 refs., 1 fig

  7. On the bursting of gene products

    CERN Document Server

    Yvinec, Romain

    2011-01-01

    In this article we demonstrate that the so-called bursting production of molecular species during gene expression may be an artifact caused by low time resolution in experimental data collection and not an actual burst in production. We reach this conclusion through an analysis of a two-stage and binary model for gene expression, and demonstrate that in the limit when mRNA degradation is much faster than protein degradation they are equivalent. The negative binomial distribution is shown to be a limiting case of the binary model for fast "on to off" state transitions and high values of the ratio between protein synthesis and degradation rates. The gene products population increases by unity but multiple times in a time interval orders of magnitude smaller than protein half-life or the precision of the experimental apparatus employed in its detection. This rare-and-fast one-by-one protein synthesis has been interpreted as bursting.

  8. Unveiling the Secrets of Gamma Ray Bursts

    CERN Document Server

    Gomboc, A

    2012-01-01

    Gamma Ray Bursts (GRBs) are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  9. A mechanism for fast radio bursts

    CERN Document Server

    Romero, Gustavo E; Vieyro, Florencia L

    2015-01-01

    Fast radio bursts are mysterious transient sources likely located at cosmological distances. The derived brightness temperatures exceed by many orders of magnitude the self-absorption limit of incoherent synchrotron radiation, implying the operation of a coherent emission process. We propose a radiation mechanism for fast radio bursts where the emission arises from collisionless Bremsstrahlung in strong plasma turbulence excited by relativistic electron beams. We discuss possible astrophysical scenarios in which this process might operate. The emitting region is a turbulent plasma hit by a relativistic jet, where Langmuir plasma waves produce a concentration of intense electrostatic soliton-like regions (cavitons). The resulting radiation is coherent and, under some physical conditions, can be polarised and have a power-law distribution in energy. We obtain radio luminosities in agreement with the inferred values for fast radio bursts. The timescale of the radio flare in some cases can be extremely fast, of t...

  10. Bursting activity spreading through asymmetric interactions

    CERN Document Server

    Onaga, Tomokatsu

    2014-01-01

    People communicate with those who have the same background or share a common interest by using a social networking service (SNS). News or messages propagate through inhomogeneous connections in an SNS by sharing or facilitating additional comments. Such human activity is known to lead to endogenous bursting in the rate of message occurrences. We analyze a multi-dimensional self-exciting process to reveal dependence of the bursting activity on the topology of connections and the distribution of interaction strength on the connections. We determine the critical conditions for the cases where interaction strength is regulated at either the point of input or output for each person. In the input regulation condition, the network may exhibit bursting with infinitesimal interaction strength, if the dispersion of the degrees diverges as in the scale-free networks. In contrast, in the output regulation condition, the critical value of interaction strength, represented by the average number of events added by a single ...

  11. Localised Microwave Bursts During ELMs on MAST

    Directory of Open Access Journals (Sweden)

    Freethy Simon

    2015-01-01

    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.

  12. Variable protostellar accretion with episodic bursts

    CERN Document Server

    Vorobyov, Eduard I

    2015-01-01

    We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model with improved disk thermal balance and star-disk interaction, we computed the evolution of protostellar disks formed from the gravitational collapse of prestellar cores. In agreement with our previous studies, we find that cores of higher initial mass and angular momentum produce disks that are more favorable to gravitational instability and fragmentation, while a higher background irradiation and magnetic fields moderate the disk tendency to fragment. The protostellar accretion in our models is time-variable, thanks to the nonlinear interaction between different spiral modes in the gravitationally unstable disk, and can undergo episodic bursts when fragments migrate onto the star owing to the gravitational interaction with other fragments or spiral arms. Most bursts occur...

  13. Gamma-ray burst polarimeter (GAP)

    International Nuclear Information System (INIS)

    The gamma-ray burst polarimeter (GAP: GAmma-ray burst Polarimeter), which had been almost handcrafted by scientists, has succeeded in working normally in interplanetary space, and in detecting the polarization of the gamma-ray from a mysterious astronomical object 'gamma-ray burst'. It is the first result of the detectors in the world exclusively aiming at detecting gamma-ray polarization. We mainly describe the hardware of our GAP equipment and show the method of preparing equipment to work in the cosmic space with a tight budget. The mechanical structure, the electronic circuits, the software on the equipment, the data analysis on the earth, and the scientific results gained by the observation just over one year, are presented after explaining the principle of gamma-ray polarization detection. Our design to protect equipment against mechanical shock and cosmic radiation may provide useful information for future preparation of compact satellite. (J.P.N.)

  14. Investigation of Primordial Black Hole Bursts Using Interplanetary Network Gamma-ray Bursts

    Science.gov (United States)

    Ukwatta, T. N.; Hurley, K.; MacGibbon, J. H.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal'shin, V. D.; Goldsten, J.; Boynton, W.; Kozyrev, A. S.; Rau, A.; von Kienlin, A.; Zhang, X.; Connaughton, V.; Yamaoka, K.; Ohno, M.; Ohmori, N.; Feroci, M.; Frontera, F.; Guidorzi, C.; Cline, T.; Gehrels, N.; Krimm, H. A.; McTiernan, J.

    2016-07-01

    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 1013–1018 cm (7–105 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.

  15. On the bimodal distribution of gamma-ray bursts

    Science.gov (United States)

    Mao, Shude; Narayan, Ramesh; Piran, Tsvi

    1994-01-01

    Kouveliotou et al. recently confirmed that gamma-ray bursts are bimodal in duration. In this paper we compute the statistical properties of the short (less than or = 2 s) and long (greater than 2 s) bursts using a method of analysis that makes no assumption regarding the location of the bursts, whether in the Galaxy or at a cosmological distance. We find the 64 ms channel on Burst and Transient Source Experiment (BATSE) to be more sensitive to short bursts and the 1024 ms channel to be more sensitive to long bursts. We show that all the currently available data are consistent with the simple hypothesis that both short and long bursts have the same spatial distribution and that within each population the sources are standard candles. The rate of short bursts per unit volume is about 40% of the rate of long bursts. Although the durations of short and long gamma-ray bursts span several orders of magnitude and the total energy of a typical short burst is smaller than that of a typical long burst by a factor of about 20, surprisingly the peak luminosities of the two kinds of bursts are equal to within a factor of about 2.

  16. Burst investigation on zircaloy-4 claddings in inert environment

    International Nuclear Information System (INIS)

    Highlights: • Burst investigations on zircaloy-4 cladding in argon environment. • Clad wall displacement measurement. • Effect of internal overpressure and heating rate on burst parameters. • Semi-empirical correlation for burst stress has been proposed. - Abstract: An extensive burst investigation has been carried out on the zircaloy-4 claddings in an inert environment to simulate clad burst during a postulated loss-of-coolant-accident (LOCA) conditions. The parameters varied during the burst experiments were heating rate and internal overpressure. The temperature, internal overpressure and ballooning data were monitored online and recorded during the heating process of burst specimen. In addition, post-experiment measurements were also conducted on the burst specimen to determine various burst parameters–burst strains and burst stress. A semi-empirical correlation was developed to predict the burst stress for a given burst temperature. A reasonable agreement between the predicted and experimental data has been observed. The proposed correlation was also compared with available established correlation for steam environment

  17. A computer based, interactive, multimedia training module for self-paced learning

    International Nuclear Information System (INIS)

    Disadvantages of traditional safeguards inspectors training methods are outlined. A computer based, interactive, multimedia, self-paced training programme, called the CANDU power reactor training module (CPRTM) is described. 1 ref., 2 figs

  18. Photovoltaics (PV) as an Eligible Measure in Residential PACE Programs: Benefits and Challenges (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    Coughlin, J.

    2010-06-01

    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.

  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: asirvatham.samuel@mayo.edu [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)

    2013-05-15

    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. Bursting Smoke as an Infrared Countermeasure

    Directory of Open Access Journals (Sweden)

    Amarjit Singh

    1998-07-01

    Full Text Available This paper describes the experimental setup for the evaluation of bursting smoke for anti-infrared role using SR-5000 spectroradiometer and a source of IR radiation (8-13 micrometer using cadmium-mercury-telluride (CMI detector cooled by liquid nitrogen. The particle size and shape of the powders used in the bursting smokes were determined microscopically using Carl Zeiss Jena Neophot- 21. Highest attenuation of 97 -lOO percent was produced for about 12 s using a mixture of bronze flakes and chaff, and for about 8 s using a mixture of bronze copper lined flakes, bronze flakes and chaff.

  1. The short gamma-ray burst revolution

    International Nuclear Information System (INIS)

    Swift, a dedicated gamma-ray burst (GRB) satellite with ultrarapid slewing capability, and a suite of ground-based (ESO) telescopes have recently achieved a major breakthrough: detecting the first afterglows of short-duration GRBs. The faintness of these afterglows and the diversity of old and young host galaxies lend support to the emerging 'standard model', in which they are created during the merging of two compact objects. However, the afterglow light-curve properties and possible high-redshift origin of some short bursts suggests that more than one progenitor type may be involved. (orig.)

  2. Threats in Optical Burst Switched Network

    Directory of Open Access Journals (Sweden)

    P. Siva Subramanian

    2011-05-01

    Full Text Available Optical network is a viable network for future communication, which transmits data at an average rate of 50Tb/s. Optical Burst Switching is a trusted mechanism used for Optical network. There is a good amount of research done in the area of security in Optical networks. In addition, the issues related to physical network security has been dealt with respect to Optical networks. Our proposed work is intend to find the possible security threats that may happen in Optical Burst Switched Networks and the counter measures are examined separately. The NS-2 simulator with modified OBS patch is used to verify and validate the proposed mechanism

  3. Exploratory depth-of-burst experiments

    Energy Technology Data Exchange (ETDEWEB)

    Reichenbach, H.; Behrens, K. [Fraunhofer-Institut fuer Kurzzeitdynamik - Ernst-Mach-Institut (EMI), Freiburg im Breisgau (Germany); Kuhl, A. [R and D Associates, Los Angeles, CA (United States)

    1991-12-12

    This report describes the first small-scale explosion experiments with aerated grout (i.e., YTONG). Apart from data referring to crater depth and volume versus depth of burst (DOB), isobaric DOB curves in the range of 1.5 psi {le} p {le} 15 psi were established. The comparison with previous HOB values shows that the ground range to a given overpressure is considerably reduced with increasing depth of burst. The authors plan to continue the airblast investigations with different types of soil materials.

  4. Spike Bursts from an Excitable Optical System

    Science.gov (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.

  5. A Shotgun Model for $\\gamma$ Ray Bursts

    CERN Document Server

    Heinz, S

    1999-01-01

    We propose that gamma ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma ray emission is produced in the shocks these bullets drive into the surrounding medium. The short term variability seen in GRBs is set by the slowing-down time of the bullets while the overall duration of the burst is set by the lifetime of the central engine. A requirement of this model is that the ambient medium be dense, consistent with a strong stellar wind. In contrast to other external shock scenarios, the efficiency of the shock can be close to unity.

  6. Processor Reformats Data For Transmission In Bursts

    Science.gov (United States)

    Steele, Glen F.

    1991-01-01

    Data-processor-and-buffer electronic system receives audio signals digitized in first standard format at relatively low data rate, rearranges data for transmission in bursts in second standard format at relatively high rate, stores second-format bursts, and releases them at higher rate upon request. Conceived for asynchronous, one-way transmission of digitized speech in outer-space communications, concept of system applied in other digital communication systems in which data transmitted from low-rate sources to high-rate sinks not synchronized with sources.

  7. EFFECT OF ADAPTIVE PACED CARDIOLOCOMOTOR SYNCHRONIZATION DURING RUNNING: A PRELIMINARY STUDY

    Directory of Open Access Journals (Sweden)

    Bill Phillips

    2013-09-01

    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

  8. Cardiac pacing device therapy for atrial dysrhythmias: how does it work?

    Science.gov (United States)

    Irwin, Marleen E

    2004-01-01

    Atrial fibrillation (AF) is the most common dysrhythmia in North America. Paroxysmal or persistent AF affects an estimated 2.8 million individuals, causes significant morbidity, and is associated with 1 billion dollars in healthcare costs each year in the United States. An aging population, the prevalence of hypertension, and the emergence of heart failure as the final common pathway of heart disease finds us in an age where the incidence of AF is ever increasing and the management challenges are indeed an expanding clinical problem. Although guidelines for selection of the appropriate pacing mode have been published, device therapy for the control of AF and paroxysmal AF is an emerging clinical management strategy. In 2001 The American College of Cardiology (ACC)/American Heart Association (AHA) published a document to revise the 1998 guidelines for device therapy, and even now these guidelines require elucidation and inclusion for the use of cardiac pacing device therapy for the control of atrial dysrhythmia. Choosing a complex system, in particular for the patient with persistent and symptomatic atrial dysrhythmia, is a most intricate challenge for the healthcare professional and the healthcare system. Rate dependent effects on refractoriness, reduction of ectopy, remodeling of the substrate, and prevention of pauses have been described as the potential mechanisms responsible for the rhythmic control effect attributed to atrial pacing. However, while permanent cardiac pacing is required for patients with symptomatic bradycardia with atrioventricular block and AF, the concept of pacing for the primary prevention of AF is novel. Pacing algorithms, single site, biatrial, and dual-site atrial pacing and site-specific pacing have all been studied as substrate modulators to prevent recurrent atrial dysrhythmia.A dilemma exists surrounding the primary approach for the control of symptomatic AF with rapid ventricular response. The question remains: should it be to

  9. The effect of shared temporal cognitions and Pacing styles on intragroup conflict in portuguese healthcare teams

    OpenAIRE

    Queimado, Alexandra Coelho de Meireles de Oliveira

    2015-01-01

    Master in Human Resources Management This study aimed to evaluate the impact of two specific dimensions of time-related matters (shared temporal cognitions and pacing styles), as a cognitive contextual factor, on different types of team conflict. We hypothesized that the relationship between shared temporal cognitions and the different types of conflict is moderated by pacing styles. A total of 30 teams (245 individuals) participated in this study. All teams were part of different Portugue...

  10. The impact of the perception of rhythmic music on self-paced oscillatory movements

    OpenAIRE

    Peckel, Mathieu; Pozzo, Thierry; Bigand, Emmanuel

    2014-01-01

    Inspired by theories of perception-action coupling and embodied music cognition, we investigated how rhythmic music perception impacts self-paced oscillatory movements. In a pilot study, we examined the kinematic parameters of self-paced oscillatory movements, walking and finger tapping using optical motion capture. In accordance with biomechanical constraints accounts of motion, we found that movements followed a hierarchical organization depending on the proximal/distal characteristic of th...

  11. Study of Access and Quality of Care in For-Profit PACE

    OpenAIRE

    David Jones; Nancy Duda; Bob Schmitz; Sandi Nelson; Chelsea Swete; Alex Bryce; Jared Coopersmith; Karen CyBulski

    2013-01-01

    This report summarizes a study to address quality of and access to care for participants of for-profit Programs of All-Inclusive Care for the Elderly (PACE) organizations. The PACE model allows people who otherwise need a nursing home-level of care to remain in the community by providing health care and related support services, such as social supports, meals and chore services, and transportation.

  12. The impact of the perception of rhythmic music on oscillatory self-paced movements

    OpenAIRE

    Mathieu ePeckel; Thierry ePozzo; Emmanuel eBigand

    2014-01-01

    Inspired by theories of perception-action coupling and embodied music cognition, we investigated how rhythmic music perception impacts self-paced oscillatory movements. In a pilot study, we examined the kinematic parameters of self-paced oscillatory movements, walking and finger tapping using optical motion capture. In accordance with biomechanical constraints accounts of motion, we found that movements followed a hierarchical organization depending on the proximal/distal characteristic of th...

  13. Potassium exchange in the human heart during atrial pacing and myocardial ischaemia.

    OpenAIRE

    Webb, S C; Poole-Wilson, P. A.

    1986-01-01

    Potassium homoeostasis in the heart was studied during atrial pacing in 20 patients undergoing diagnostic coronary angiography. The potassium concentrations in the coronary sinus and a systemic artery were recorded continuously by means of catheter tip potassium electrodes. Ten patients with coronary artery disease and a positive exercise test developed chest pain and ST segment depression on the electrocardiogram during atrial pacing. Potassium concentrations in the coronary sinus rose initi...

  14. SDSS Pre-Burst Observations of Recent Gamma-Ray Burst Fields

    CERN Document Server

    Cool, R J; Brinkmann, J; Eisenstein, D J; Hogg, D W; Schlegel, D J; Schneider, D P; Vanden Berk, Daniel E; Berk, Daniel E. Vanden; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Hogg, David W.; Schlegel, David J.; Schneider, Donald P.

    2006-01-01

    In this paper, we present Sloan Digital Sky Survey (SDSS) photometry and spectroscopy in the fields of 24 gamma-ray bursts (GRBs) observed by Swift, including bursts localized by Swift, HETE-2, and INTEGRAL, after December 2004. After this bulk release, we plan to provide individual releases of similar data shortly after the localization of future bursts falling in the SDSS survey area. These data provide a solid basis for the astrometric and photometric calibration of follow-up afterglow searches and monitoring. Furthermore, the images provided with this release will allow observers to find transient objects up to a magnitude fainter than possible with Digitized Sky Survey image comparisons.

  15. The effect of visitor number and spice provisioning in pacing expression by jaguars evaluated through a case study.

    Science.gov (United States)

    Vidal, L S; Guilherme, F R; Silva, V F; Faccio, M C S R; Martins, M M; Briani, D C

    2016-06-01

    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. PMID:26959957

  16. New Results on the Spectral Evolution of Magnetar Bright Bursts

    Science.gov (United States)

    Younes, George A.; Kouveliotou, C.; van der Horst, A.; GBM Magnetar Team

    2013-04-01

    Magnetars are isolated neutron stars characterized by long spin periods (2-12 s) and large spin down rates, implying a very strong magnetic field, B>10E14 G. Magnetars exhibit short bursts of hard X-/soft gamma-rays with luminosities ranging from 10E37 to 10E41 erg/s. The magnetar SGR J1550-5418 entered an extremely active bursting episode, starting on 2008 October 03 until 2009 April 17, during which Fermi Gamma-ray Burst Monitor (GBM) observed several hundred bursts from this source. Such wealth of bursts resulted in the largest catalog of detailed temporal and spectral results for SGR J1550-5418. Here, we discuss new results from time-resolved spectral analysis of the brightest bursts from this source. Our analysis, together with the comparison of our results with other magnetar bursts, enabled us to put strong constraints on the theories underlying the magnetar bursts emission mechanism.

  17. The Five Year Fermi/GBM Magnetar Burst Catalog

    Science.gov (United States)

    Collazzi, A. C.; Kouveliotou, C.; van der Horst, A. J.; Younes, G. A.; Kaneko, Y.; Göğüş, E.; Lin, L.; Granot, J.; Finger, M. H.; Chaplin, V. L.; Huppenkothen, D.; Watts, A. L.; von Kienlin, A.; Baring, M. G.; Gruber, D.; Bhat, P. N.; Gibby, M. H.; Gehrels, N.; McEnery, J.; van der Klis, M.; Wijers, R. A. M. J.

    2015-05-01

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here, we present the Fermi/GBM magnetar catalog, providing the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from 2008 July to 2013 June. We provide durations, spectral parameters for various models, fluences, and peak fluxes for all the bursts, as well as a detailed temporal analysis for SGR J1550-5418 bursts. Finally, we suggest that some of the bursts of unknown origin are associated with the newly discovered magnetar 3XMM J185246.6+0033.7.

  18. The Five Year Fermi/GBM Magnetar Burst Catalog

    CERN Document Server

    Collazzi, A C; van der Horst, A J; Younes, G A; Kaneko, Y; Gogus, E; Lin, L; Granot, J; Finger, M H; Chaplin, V L; Huppenkothen, D; Watts, A L; von Kienlin, A; Baring, M G; Gruber, D; Bhat, P N; Gibby, M H; Gehrels, N; McEnery, J; van der Klis, M; Wijers, R A M J

    2015-01-01

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here we present the Fermi/GBM magnetar catalog, giving the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from July 2008 to June 2013. We provide durations, spectral parameters for various models, fluences and peak fluxes for all the bursts, as well as a detailed temporal analysis for SGR J1550-5418 bursts. Finally, we suggest that some of the bursts of unknown origin are associated with the newly discovered magnetar 3XMM J185246.6+0033.7.

  19. Statistical properties of SGR 1806-20 bursts

    CERN Document Server

    Gogus, E; Kouveliotou, C; Van Paradijs, J; Briggs, M S; Duncan, R C; Thompson, C; Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; Paradijs, Jan van; Briggs, Michael S.; Duncan, Robert C.; Thompson, Christopher

    2000-01-01

    We present statistics of SGR 1806-20 bursts, combining 290 events detectedwith RXTE/PCA, 111 events detected with BATSE and 134 events detected with ICE.We find that the fluence distribution of bursts observed with each instrumentare well described by power laws with indices 1.43, 1.76 and 1.67,respectively. The distribution of time intervals between successive bursts fromSGR 1806-20 is described by a lognormal function with a peak at 103 s. There isno correlation between the burst intensity and either the waiting times tillthe next burst or the time elapsed since the previous burst. In all thesestatistical properties, SGR 1806-20 bursts resemble a self-organized criticalsystem, similar to earthquakes and solar flares. Our results thus support thehypothesis that the energy source for SGR bursts is crustquakes due to theevolving, strong magnetic field of the neutron star, rather than any accretionor nuclear power.

  20. ESTIMATION OF THE BURST LENGTH IN OBS NETWORKS

    Directory of Open Access Journals (Sweden)

    Pallavi S.

    2014-05-01

    Full Text Available This paper presents an overview of the optical burst switching (OBS and discusses the major components. In OBS, the length of the burst arriving at a particular node is unknown, and hence, node design is very complex. In OBS first control, packet is transmitted and reserve the path as in circuit switching, thereafter, the data bursts is transmitted. In this paper, a poisson arrival of packets is considered and estimation is made on the size of the burst length. The results presented in the paper clearly reveal that, the very large burst length is un-common. Therefore, most of the times, very short or average length burst is expected. Therefore it is concluded in this paper, buffering of burst at the contending nodes is a good option which increases the throughput and reduces the average delay. Finally, the buffering in conjunction with deflection of bursts will provide very effective solution.

  1. THE FERMI-GBM X-RAY BURST MONITOR: THERMONUCLEAR BURSTS FROM 4U 0614+09

    Energy Technology Data Exchange (ETDEWEB)

    Linares, M.; Chakrabarty, D. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Connaughton, V.; Bhat, P. N.; Briggs, M. S.; Preece, R. [CSPAR and Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Jenke, P.; Kouveliotou, C.; Wilson-Hodge, C. A. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, A. J. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, NL-1090-GE Amsterdam (Netherlands); Camero-Arranz, A.; Finger, M.; Paciesas, W. S. [Universities Space Research Association, Huntsville, AL 35805 (United States); Beklen, E. [Physics Department, Suleyman Demirel University, 32260 Isparta (Turkey); Von Kienlin, A. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, D-85748 Garching (Germany)

    2012-12-01

    Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the NS interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09 when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12 {+-} 3 days (68% confidence interval) between 2010 March and 2011 March, classified all bursts as normal duration bursts and placed a lower limit on the recurrence time of long/intermediate bursts of 62 days (95% confidence level). We discuss how observations of thermonuclear bursts in the hard X-ray band compare to pointed soft X-ray observations and quantify such bandpass effects on measurements of burst radiated energy and duration. We put our results for 4U 0614+09 in the context of other bursters and briefly discuss the constraints on ignition models. Interestingly, we find that the burst energies in 4U 0614+09 are on average between those of normal duration bursts and those measured in long/intermediate bursts. Such a continuous distribution in burst energy provides a new observational link between normal and long/intermediate bursts. We suggest that the apparent bimodal distribution that defined normal and long/intermediate duration bursts during the last decade could be due to an observational bias toward detecting only the longest and most energetic bursts from slowly accreting NSs.

  2. The Fermi-GBM X-Ray Burst Monitor: Thermonuclear Bursts from 4U 0614+09

    Science.gov (United States)

    Linares, M.; Connaughton, V.; Jenke, P.; van der Horst, A. J.; Camero-Arranz, A.; Kouveliotou, C.; Chakrabarty, D.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Finger, M.; Paciesas, W. S.; Preece, R.; von Kienlin, A.; Wilson-Hodge, C. A.

    2012-12-01

    Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the NS interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09 when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12 ± 3 days (68% confidence interval) between 2010 March and 2011 March, classified all bursts as normal duration bursts and placed a lower limit on the recurrence time of long/intermediate bursts of 62 days (95% confidence level). We discuss how observations of thermonuclear bursts in the hard X-ray band compare to pointed soft X-ray observations and quantify such bandpass effects on measurements of burst radiated energy and duration. We put our results for 4U 0614+09 in the context of other bursters and briefly discuss the constraints on ignition models. Interestingly, we find that the burst energies in 4U 0614+09 are on average between those of normal duration bursts and those measured in long/intermediate bursts. Such a continuous distribution in burst energy provides a new observational link between normal and long/intermediate bursts. We suggest that the apparent bimodal distribution that defined normal and long/intermediate duration bursts during the last decade could be due to an observational bias toward detecting only the longest and most energetic bursts from slowly accreting NSs.

  3. Colony pace: a life-history trait affecting social insect epidemiology.

    Science.gov (United States)

    Buechel, Séverine Denise; Schmid-Hempel, Paul

    2016-01-13

    Among colonies of social insects, the worker turnover rate (colony 'pace') typically shows considerable variation. This has epidemiological consequences for parasites, because in 'fast-paced' colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. Here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. We infected bumblebees (Bombus terrestris) with the infectious gut parasite Crithidia bombi, and experimentally manipulated birth and death rates to mimic slow and fast pace. We found that fewer workers and, importantly, fewer last-generation workers that are responsible for rearing sexuals were infected in colonies with faster pace. This translates into increased fitness in fast-paced colonies, as daughter queens exposed to fewer infected workers in the nest are less likely to become infected themselves, and have a higher chance of founding their own colonies in the next year. High worker turnover rate can thus act as a strategy of defence against a spreading infection in social insect colonies. PMID:26763696

  4. IPN localizations of Konus short gamma-ray bursts

    CERN Document Server

    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; Cline, T; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Boynton, W; Fellows, C; Harshman, K; Trombka, J; McClanahan, T; Starr, R; Goldsten, J; Gold, R; Rau, A; von Kienlin, A; Savchenko, V; Smith, D M; Hajdas, W; Barthelmy, S D; Cummings, J; Gehrels, N; Krimm, H; Palmer, D; Yamaoka, K; Ohno, M; Fukazawa, Y; Hanabata, Y; Takahashi, T; Tashiro, M; Terada, Y; Murakami, T; Makishima, K; Briggs, M S; Kippen, R M; Kouveliotou, C; Meegan, C; Fishman, G; Connaughton, V; Boer, M; Guidorzi, C; Frontera, F; Montanari, E; Rossi, F; Feroci, M; Amati, L; Nicastro, L; Orlandini, M; Monte, Del; Costa, E; Donnarumma, I; Evangelista, Y; Lapshov, I; Lazzarotto, F; Pacciani, L; Rapisarda, M; Soffitta, P; Di Cocco, G; Fuschino, F; Galli, M; Labanti, C; Marisaldi, M; Atteia, J -L; Vanderspek, R; Ricker, G

    2013-01-01

    Between the launch of the GGS Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 314 short-duration gamma-ray bursts (including 24 bursts which can be classified as short bursts with extended emission). During this period, the IPN consisted of up to eleven spacecraft, and using triangulation, the localizations of 276 bursts were obtained. We present the IPN localization data on these events.

  5. 47 CFR 90.250 - Meteor burst communications.

    Science.gov (United States)

    2010-10-01

    ... 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...

  6. $\\gamma$-ray Burst Positions from the ASM on RXTE

    CERN Document Server

    Bradt, H V; Bradt, Hale V.; Smith, Donald A.

    1999-01-01

    The RXTE/ASM has detected and positioned 14 confirmed GRB bursts (at this writing, Jan. 1999) including six whose positions were comunicated to the community 2 to 32 hours after the burst. Two of these latter bursts led to measurements of optical red shifts but one, despite an easily detected x-ray afterglow, produced no detectable optical or radio afterglow.

  7. The position and polarization of Type III solar bursts

    Science.gov (United States)

    Dulk, G. A.; Suzuki, S.

    1980-01-01

    The position and polarization of Type III solar bursts in the range of 24-220 MHz are studied, with emphasis on the bursts continuing to frequencies lower than 24 MHz. Consideration is given to the statistics of burst polarization, the relation between polarization and source position, and brightness temperature, flux densities, and source sizes.

  8. Search for bursts in air shower data

    Science.gov (United States)

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

    1985-01-01

    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 ime 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.

  9. Fast Radio Bursts: Searches, Sensitivities & Implications

    CERN Document Server

    Keane, E F

    2016-01-01

    Fast radio bursts (FRBs) are millisecond-duration transient signals discovered over the past decade. Here we describe the scientific usefulness of FRBs, consider ongoing work at the Parkes telescope, and examine some relevant search sensitivity and completeness considerations. We also look ahead to the results from ongoing and future planned studies in the field.

  10. PHYSICAL CONSTRAINTS ON FAST RADIO BURSTS

    International Nuclear Information System (INIS)

    Fast radio bursts (FRBs) are isolated, ms radio pulses with dispersion measure (DM) of order 103 pc cm–3. Galactic candidates for the DM of high latitude bursts detected at GHz frequencies are easily dismissed. DM from bursts emitted in stellar coronas are limited by free-free absorption and those from H II regions are bounded by the nondetection of associated free-free emission at radio wavelengths. Thus, if astronomical, FRBs are probably extragalactic. FRB 110220 has a scattering tail of ∼5.6 ± 0.1 ms. If the electron density fluctuations arise from a turbulent cascade, the scattering is unlikely to be due to propagation through the diffuse intergalactic plasma. A more plausible explanation is that this burst sits in the central region of its host galaxy. Pulse durations of order ms constrain the sizes of FRB sources implying high brightness temperatures that indicates coherent emission. Electric fields near FRBs at cosmological distances would be so strong that they could accelerate free electrons from rest to relativistic energies in a single wave period

  11. Gamma-Ray Bursts and Cosmology

    Science.gov (United States)

    Norris, Jay P.

    2003-01-01

    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.

  12. The Swift Gamma Ray Burst Mission

    Science.gov (United States)

    Gehrels, Neil

    2004-01-01

    Swift is an international mission managed by NASA as part of its MIDEX program. It is a multiwavelength transient observatory for GRB astronomy that will launch in 2004. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. A wide field gamma-ray camera will detect more than a hundred GRBs per year to 2-5 times fainter than BATSE. Sensitive narrow-field X-ray, and UV/optical telescopes will be pointed at the burst location in 20 to 75 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/x-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approx. 0.5 square meter) CdZnTe detector array. The instruments have now completed their fabrication phase and are integrated on the observatory for final testing. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift. The talk will describe the mission and its status and give a summary of our plans for GRB operations.

  13. The Swift Gamna-Ray Burst Mission

    Science.gov (United States)

    Gehrels, Neil

    2005-01-01

    Swift is a NASA Explorer mission that will be launched in late 2004. It is a multiwavelength observatory for transient astronomy. The goals of the mission are to determine the origin of gamma-ray bursts and their afterglows and use bursts to probe the early Universe. The mission will also perform a hard x-ray survey at the 1 milliCrab level and will continuously monitor the sky for transients. A wide-field gamma-ray camera will detect more than a hundred GRBs per year to 3 times fainter than BATSE. Sensitive narrow-field X-ray and UV/optical telescopes will be pointed at the burst location in 20 to 70 sec by an autonomously controlled "swift" spacecraft. For each burst, arcsec positions will be determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. The instrumentation is a combination of existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (-0.5 square meter) CdZnTe detector array. The ground station in Malindi is contributed by the Italian Space Agency. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift.

  14. Neutrino Balls and Gamma-Ray Bursts

    CERN Document Server

    Holdom, B

    1994-01-01

    We propose a mechanism by which the neutrino emission from a supernova-type explosion can be converted into a gamma-ray burst of total energy $\\sim 10^{50}$ ergs. This occurs naturally if the explosion is situated inside a ball of trapped neutrinos, which in turn may lie at a galactic core. There are possible unique signatures of this scenario.

  15. K+ channels and the microglial respiratory burst.

    Science.gov (United States)

    Khanna, R; Roy, L; Zhu, X; Schlichter, L C

    2001-04-01

    Microglial activation following central nervous system damage or disease often culminates in a respiratory burst that is necessary for antimicrobial function, but, paradoxically, can damage bystander cells. We show that several K+ channels are expressed and play a role in the respiratory burst of cultured rat microglia. Three pharmacologically separable K+ currents had properties of Kv1.3 and the Ca2+/calmodulin-gated channels, SK2, SK3, and SK4. mRNA was detected for Kv1.3, Kv1.5, SK2, and/or SK3, and SK4. Protein was detected for Kv1.3, Kv1.5, and SK3 (selective SK2 and SK4 antibodies not available). No Kv1.5-like current was detected, and confocal immunofluorescence showed the protein to be subcellular, in contrast to the robust membrane localization of Kv1.3. To determine whether any of these channels play a role in microglial activation, a respiratory burst was stimulated with phorbol 12-myristate 13-acetate and measured using a single cell, fluorescence-based dihydrorhodamine 123 assay. The respiratory burst was markedly inhibited by blockers of SK2 (apamin) and SK4 channels (clotrimazole and charybdotoxin), and to a lesser extent, by the potent Kv1.3 blocker agitoxin-2. PMID:11245596

  16. Pacing-induced ST segment deviation in patients with unstable angina: clinical, angiographic, and hemodynamic correlation.

    Science.gov (United States)

    Hussain, K M; Gould, L; Pomerantsev, E V; Angirekula, M; Bharathan, T

    1995-07-01

    To assess the clinical, coronary arteriographic, and hemodynamic differences between the unstable angina patients manifesting ST segment depression and those showing ST segment elevation as well as those demonstrating chest pain only without ST segment deviation during pacing, low-dose digital subtraction ventriculography was performed in 33 patients before and after abrupt cessation of atrial pacing during selective coronary arteriography. Transient ST segment depression during pacing was observed in 17 patients (52%), whereas 6 patients (18%) showed ST segment elevation; however, 10 patients (30%) did not manifest any ST segment deviation in spite of typical chest pain. Hypertension and a history of myocardial infarction were observed in a significantly higher (P < 0.05) proportion of patients with ST segment depression than in those with ST elevation. Patients who manifested ST segment depression during pacing had a higher incidence of triple-vessel disease (65 vs 17%; P < .05) as compared with the patients with ST segment elevation. Indirect evidence of intracoronary thrombi (complicated lesion, abrupt occlusion, and intraluminal filling defect) was noticed in a higher frequency (P < 0.05) in the group of patients with ST elevation during pacing. In patients with ST segment depression, no significant changes of global left ventricular (LV) functional parameters were observed. However, the length of the LV severe hypokinetic region was increased significantly (6.2 +/- 3.1 vs 23.5 +/- 6.2%; P < 0.005) during pacing in this group of patients. The shortening of the affected segments of the left ventricle was decreased significantly (52.3 +/- 3.6 vs 38.3 +/- 4.9%; P < 0.05) in these patients during pacing. In the group of patients with ST segment elevation during pacing, decrease in ejection fraction was associated with significant (P < 0.01) increase in midwall equatorial diastolic stress as compared with the patients with pacing-induced ST segment depression as

  17. Burst Assembly Schemes and Performance Evaluation in Optical Burst Switching Networks

    Institute of Scientific and Technical Information of China (English)

    TANG Jian-jun; JI Yue-feng

    2004-01-01

    Several proposed assemble algorithms for Optical Burst Switching (OBS) network is described, and the feature relative merits is discussed and analyzed in this paper. The authors propose an assembly mechanism FAT where time threshold is fluctuating randomly to reduce continuous blocking rate. With network simulation, the basic performance of these assembly schemes is compared and analyzed. The results show that burst loss ratio and assembly delay of the proposed FAT mechanism is better than that of exist assemble mechanism.

  18. Improved adaptive-threshold burst assembly in optical burst switching networks

    Institute of Scientific and Technical Information of China (English)

    Jiuru Yang; Gang Wang; Shilou Jia

    2007-01-01

    An improved adaptive-threshold burst assembly algorithm is proposed to alleviate the limitation of conventional assembly schemes on data loss and delay. The algorithm will adjust the values of assembly factors according to variant traffic regions. And the simulation results show that, by using the adaptive-factor adaptive assembly scheme, the performance of networks is extensively enhanced in terms of burst loss probability and average queuing delay.

  19. Can Pacing Be Regulated by Post-Activation Potentiation? Insights from a Self-Paced 30 km Trial in Half-Marathon Runners

    Science.gov (United States)

    Del Rosso, Sebastián; Barros, Edilberto; Tonello, Laís; Oliveira-Silva, Iransé; Behm, David G.; Foster, Carl; Boullosa, Daniel A.

    2016-01-01

    Purpose Given the co-existence of post-activation potentiation (PAP) and fatigue within muscle, it is not known whether PAP could influence performance and pacing during distance running by moderating fatigue. The aim of this study was to assess the influence of PAP on pacing, jumping and other physiological measures during a self-paced 30 km trial. Methods Eleven male endurance-trained runners (half-marathon runners) volunteered to participate in this study. Runners participated in a multi-stage 30 km trial. Before the trial started, determination of baseline blood lactate (bLa) and countermovement jump (CMJ) height was performed. The self-paced 30 km trial consisted of 6 × 5 km splits. At the end of each 5 km split (60 s break), data on time to complete the split, CMJ height, Rating of Perceived Exertion (RPE) and blood lactate were collected while heart rate was continuously monitored. Results There was a significant decrease in speed (e.g. positive pacing strategy after the 4th split, p<0.05) with a progressive increase in RPE throughout the trial. Compared with baseline, CMJ height was significantly (p<0.05) greater than baseline and was maintained until the end of the trial with an increase after the 5th split, concomitant with a significant reduction in speed and an increase in RPE. Significant correlations were found between ΔCMJ and ΔSPEED (r = 0.77 to 0.87, p<0.05) at different time points as well as between RPE and speed (r = -0.61 to -0.82, p<0.05). Conclusion Our results indicates that fatigue and potentiation co-exist during long lasting endurance events, and that the observed increase in jump performance towards the end of the trial could be reflecting a greater potentiation potentially perhaps counteracting the effects of fatigue and preventing further reductions in speed. PMID:26934357

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

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram

    2007-01-01

    cells are subjected to stochastic fluctuations in plasma membrane currents, which are likely to disturb the bursting mechanism and transform medium bursters into spikers or very fast bursters. We present a polynomial, minimal, phantom burster model and show that noise modifies the plateau fraction and......-called compound bursting can be converted to apparent slow bursting by noise, which could explain why compound bursting and mixed Ca oscillations are seen mainly in intact islets....

  1. Imaging assessment of vertebral burst fracture

    International Nuclear Information System (INIS)

    Objective: To investigate the diagnostic value of radiography, CT and MRI in diagnosis of vertebral burst fracture. Methods: 51 patients with vertebral burst fracture were evaluated with X-ray, CT and MRI, including 3 cases in cervical vertebra, 18 cases in thoracic vertebra, and 30 cases in lumbar vertebra. The imaging features were comparatively studied. Results: Radiography showed decreased height of the vertebral body, increased antero-posterior diameter and the transverse diameter, and/or the widened interpedicle distance, the inter-spinous distance, as well as the bony fragment inserted into the vertebral canal in 28 cases(54.90%). X-ray findings similar to the compression fracture were revealed in 20 cases(39.21%). And missed diagnosis was made in 3 cases (5.88%). CT clearly demon-strated the vertebral body vertically or transversely burst crack in 49 cases (96.07%); bony fragment inserted into the vertebral canal and narrowed vertebral canal in 35 cases(68. 62% ); fracture of spinal appendix in 22 cases(43.14%). Meanwhile MRI showed abnormal signals within the spinal cord in 35 cases (68.62%),injured intervertebral disk in 29 cases(56.86% ), extradural hematoma in 12 cases(23.52% ) and torn posterior longitudinal ligament in 6 cases (11.76%). Conclusions: Radiography is the routine examination, while with limited diagnostic value in vertebral burst fracture. These patients who have nervous symptoms with simple compression fracture or unremarkable on X-ray should receive the CT or MRI examination. CT is better than MRI in demonstrating the fracture and the displaced bony fragment, while MRI is superior to CT in showing nervous injuries. CT and MRI will provide comprehensive information guiding clinical treatment of vertebral burst fracture. (authors)

  2. Investigation of Primordial Black Hole Bursts using Interplanetary Network Gamma-ray Bursts

    CERN Document Server

    Ukwatta, T N; MacGibbon, J H; Svinkin, D S; Aptekar, R L; Golenetskii, S V; Frederiks, D D; Pal'shin, V D; Goldsten, J; Boynton, W; Fellows, C; Harshman, K; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Rau, A; Kienlin, A; Zhang, X; Briggs, M S; Connaughton, V; Meegan, C; Yamaoka, K; Fukazawa, Y; Ohno, M; Ohmori, N; Takahashi, T; Tashiro, M; Terada, Y; Murakami, T; Makishima, K; Feroci, M; Frontera, F; Guidorzi, C; Barthelmy, S; Cline, T; Gehrels, N; Cummings, J; Krimm, H A; Smith, D M; McTiernan, J

    2015-01-01

    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 minimum distance to gamma-ray bursts using detections from widely separated spacecraft. 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 10^13-10^18 cm (7-10^5 AU) range, 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 these bursts are real PBH events, we estimate for the first time lower limits ...

  3. Powerful Radio Burst Indicates New Astronomical Phenomenon

    Science.gov (United States)

    2007-09-01

    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

  4. Exercise performance in young patients with complete atrioventricular block: the relevance of synchronous atrioventricular pacing.

    Science.gov (United States)

    Gonzalez Corcia, M Cecilia; Remy, Lorraine Saint; Marchandise, Sebastien; Moniotte, Stephane

    2016-08-01

    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. PMID:26796814

  5. 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.

  6. Diritto internazionale umanitario, guerra e pace, diritti delle persone

    Directory of Open Access Journals (Sweden)

    Giovanni Barberini

    2011-11-01

    Full Text Available SOMMARIO: 1. Il diritto umanitario nei conflitti armati - 2. La codificazione del diritto umanitario - 3. Diritto della guerra e diritto della pace - 4. L’articolo 11 della costituzione italiana - 5. La protezione internazionale dei diritti e delle libertà della persona - 6. Conclusioni. Abstract: The military operators must also assure the peace with the weapons and, above all, the persons responsible of the operations must give test of great sensibility because busy to conjugate laws and rules war with the objectives of pacification. The authorities responsible for the operations at any time they need to know what they can or must do and what orders impart; they must know what it cannot do or what should be avoided. The international humanitarian law, important part of the international law, is constituted by conventional and consuetudinary norms that are applied in the relationships among States with a specific objective: to protect in time of armed conflict the people who do not take part or do not take more part in hostilities and impose bans or limits to the use of means offensive, of sophisticated weapons and methods of warfare in situations of armed conflict in act or to avoid sleepwalking. The codification of the international humanitarian law is initiated in the century XIX, above all when it was tried to introduce with the Declaration of Petersbourg in 1868 a principle that individualized in the contrariety to the laws of the humanity the impassable limit to respect in the armed conflicts. The codification has received then force and importance after the second world conflict that the consciences of the people had struck with the systematic practice of the most merciless violence making to record million of deads. The fundamental importance of the 1949 Geneva four Conventions is unanimously recognized. They are based on ratio of the existence and the responsibilities of the Organization of United Nations; they have properly

  7. X-Ray Observations of Gamma-Ray Burst Afterglows

    OpenAIRE

    Frontera, Filippo

    2004-01-01

    The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long $\\gamma$-ray bursts. The 30 year mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I rewiew the observationa...

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    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 a...... intermediate between pure He and mixed H/He burning. The long burst is the result of the accumulation of a thick He layer, while the short one is a prematurate H-triggered He burning burst at a slightly lower accretion rate....

  9. Gravitational-wave bursts with memory and experimental prospects

    International Nuclear Information System (INIS)

    The authors show that for any kind of detector the best way to search for a ''bursts with memory'' (BWM) gravitation wave is to integrate up the signal for an integration time tau-circumflex approx.= 1/fsub(opt), where fsub(opt) is the frequency at which the detector has optimal amplitude sensitivity to ordinary bursts (bursts with memory). In such a search the sensitivity to BWM with duration Δt < or approx. 1/fsub(opt) is independent of the burst duration Δt and is approximately equal to the sensitivity to ordinary bursts one cycle long with frequency fsub(opt). (author)

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

    OpenAIRE

    Vacek, J.; J. Chocholoušová

    2008-01-01

    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 pot...

  11. Directivity of low frequency solar type III radio bursts

    International Nuclear Information System (INIS)

    The occurrence rate of type III solar bursts in the frequency range 4.9 MHz to 30 kHz is analyzed as a function of burst intensity and burst arrival direction. It is found that (a) the occurrence rate of bursts falls off with increasing flux, S, according to the power law Ssup(-1.5), and (b) the distribution of burst arrival directions at each frequency shows a significantly larger number of bursts observed west of the Earth-Sun line than east of it. This western excess in occurrence rate appears to be correlated with the direction of the average interplanetary magnetic field, and is interpreted as beaming of the observed burst radiation along the magnetic field direction. (Auth.)

  12. An Analysis of Burst Disc Pressure Instability

    Energy Technology Data Exchange (ETDEWEB)

    S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

    2000-06-01

    During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation

  13. Application of PACE Principles for Population Health Management of Frail Older Adults.

    Science.gov (United States)

    Stefanacci, Richard G; Reich, Shelley; Casiano, Alex

    2015-10-01

    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. PMID:25647691

  14. Aliskiren protecting atrial structural remodeling from rapid atrial pacing in a canine model.

    Science.gov (United States)

    Zhao, Zhiqiang; Chen, Yan; Li, Weimin; Wang, Xinghua; Li, Jian; Yang, Wansong; Cheng, Lijun; Liu, Tong; Liu, Enzhao; Li, Guangping

    2016-08-01

    Atrial fibrillation (AF) contributing to the increasing mortality risk is the most common disease in clinical practice. Owing to the side effects and relative inefficacy of current antiarrhythmic drugs, some research focuses on renin-angiotensin-aldosterone system (RAS) for finding out the new treatment of AF. The purpose of this study is to confirm whether aliskiren as a proximal inhibitor of renin, which completely inhibits RAS, has beneficial effects on atrial structural remodeling in AF. In this study, rapid atrial pacing was induced at 500 beats per minute for 2 weeks in a canine model. A different dose of aliskiren was given orally for 2 weeks before rapid atrial pacing. HE staining and Masson's staining were used for analysis of myocardial fibrosis. TGF-β1, signal pathways, and pro-inflammatory cytokines were shown for the mechanism of structural remodeling after the treatment of aliskiren. Serious atrial fibrosis was induced by rapid atrial pacing, followed by the elevated TGF-β1, upregulated MEK and ERK1/2, and increased inflammatory factors. Aliskiren could apparently improve myocardial fibrosis by reducing the expression of TGF-β1, inhibiting MEK and ERK1/2 signal pathways, and decreasing IL-18 and TLR4 in both serum and atrial tissue. In conclusion, aliskiren could prevent atrial structural remodeling from rapid atrial pacing for 2 weeks. Aliskiren may play a potential beneficial role in the treatment of AF induced by rapid atrial pacing. PMID:27118660

  15. Potential Effect of Physical Activity Calorie Equivalent (PACE Labeling on Adult Fast Food Ordering and Exercise.

    Directory of Open Access Journals (Sweden)

    Ray Antonelli

    Full Text Available Numeric calorie content labels show limited efficacy in reducing the number of calories ordered from fast food meals. Physical activity calorie equivalent (PACE labels are an alternative that may reduce the number of calories ordered in fast food meals while encouraging patrons to exercise.A total of 1000 adults from 47 US states were randomly assigned via internet survey to one of four generic fast food menus: no label, calories only, calories + minutes, or calories + miles necessary to walk to burn off the calories. After completing hypothetical orders participants were asked to rate the likelihood of calorie-only and PACE labels to influence (1 food choice and (2 physical activity.Respondents (n = 823 ordered a median of 1580 calories from the no-label menu, 1200 from the calories-only menu, 1140 from the calories + minutes menu, and 1210 from the calories + miles menu (p = 0.0001. 40% of respondents reported that PACE labels were "very likely" to influence food item choice vs. 28% for calorie-only labels (p<0.0001. 64% of participants reported that PACE labels were "somewhat likely" or "very likely" to influence their level of physical activity vs. 49% for calorie-only labels (p<0.0001.PACE labels may be helpful in reducing the number of calories ordered in fast food meals and may have the added benefit of encouraging exercise.

  16. Influence of filling on left ventricular diastolic pressure-volume curve during pacing ischemia in dogs.

    Science.gov (United States)

    Shintani, H; Glantz, S A

    1994-04-01

    The reversible upward shift of the diastolic pressure-volume curve that occurs during pacing-induced ischemia has not been fully explained by increases in passive chamber stiffness or reductions in relaxation rate. We measured the fully relaxed pressure-volume relation defined by both filling and nonfilling beats and the isovolumic relaxation time constant in nonfilling beats before and during demand ischemia using our in situ left ventricular volume clamping technique in 10 dogs. Pacing-induced ischemia shifted the diastolic pressure-volume curves in filling beats upward compared with the end-diastolic pressure-volume relation of the normally perfused heart. In contrast, the end-diastolic points for nonfilling beats during pacing-induced ischemia fell on the fully relaxed pressure-volume relation defined by the normally perfused heart. Left ventricular filling per se was necessary for the upward shift of the diastolic pressure-volume curve observed during pacing-induced ischemia. We speculate that active force developed during diastole induced by stretch activation or, perhaps, length-dependent changes in calcium sensitivity of the myofilaments in the ischemic myocardium due to stretch of the myocardium during rapid diastolic filling may contribute to the upward shift of the diastolic pressure-volume curve observed during pacing-induced ischemia. PMID:8184915

  17. High Frequency ELM Pacing by Lithium Pellet Injection on DIII-D

    Science.gov (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.

    2015-11-01

    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.

  18. Indications for dual-chamber (DDD) pacing in implantable cardioverter-defibrillator patients.

    Science.gov (United States)

    Santini, M; Ansalone, G; Auriti, A; Magris, B; Pandozi, C; Altamura, G

    1996-09-12

    New technologic development of implantable cardioverter-defibrillators (ICDs) keeps up with the exponential increase of their use for primary and secondary prevention of sudden cardiac death. The first-generation ICD with limited shock capability alone could be considered adequate in most cardiac arrest victims, but it was not suitable for sudden death prevention in all high-risk patients with cardiac disease. The second-generation ICD was comprised of hybrid pacemaker-defibrillator systems that provided on-demand ventricular antibradycardia pacing. The third-generation devices include additional functions, such as antitachycardia pacing for ventricular tachycardia (VT) reversion and low-energy ventricular cardioversion, in addition to ventricular defibrillation and single-chamber ventricular demand pacing. In the near future, advanced dual-chamber atrioventricular (AV) pacing and defibrillating systems will also be available. The dual chamber ICD will allow atrial inhibited/dual-chamber (AAI/DDD) rate-responsive pacing, simultaneous atrial and ventricular sensing to optimize the arrhythmia identification, and ICD shock delivery in the proper arrhythmia-related chamber. Clinical benefits of these devices compared with their cost and complexity will require careful evaluation. PMID:8820847

  19. CATHENA/PACE calculations of aerosol transport in a simulated primary circuit

    International Nuclear Information System (INIS)

    Severe fuel damage in postulated loss-of-coolant accidents (LOCAs) in CANDU (Canada Deuterium Uranium) reactors may result in the release and transport of aerosol fission product materials from the fuel, through the primary circuit to containment and possibly into the atmosphere. In order to obtain a greater understanding of the mechanisms underlying fission product release, transport and deposition resulting from fuel damage in such accidents, a series of COG funded (Candu Owners Group) severe fuel damage experiments have been planned in the Blowdown Test Facility (BTF) at AECL Research, Chalk River. One of the planned experiments, BTF-104, has been simulated with the thermalhydraulics/aerosol transport code CATHENA/PACE, as a pretest investigation of fission product transport behaviour. Results of a number of CATHENA/PACE pretest simulations of the BTF-104 experiment are reported in this paper. The CATHENA code, developed at Whiteshell Laboratories, has been used to model the thermalhydraulic phenomena in a section of primary circuit piping representing the BTF. The PACE code (a Program for Aerosol Code Evaluation), also developed at Whiteshell, is coupled to the thermahydraulic calculations of CATHENA to model the transport of the aerosol fission products generated from the fuel. The PACE code contains aerosol physics models from a number of aerosol codes (e.g., HAA4, REMOVAL, NAUA, AEROSIM, etc.) and can therefore emulate any one of these by user selection. A number of codes (including VICTORIA, AEROSIM, REMOVAL, AND HAARM) were emulated with CATHENA/PACE for aerosol transport in this circuit

  20. Fermi/GAMMA-RAY BURST MONITOR OBSERVATIONS OF SGR J0501+4516 BURSTS

    International Nuclear Information System (INIS)

    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 T90 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 T90 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 Epeak 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, Liso, corresponding to these flux values is roughly similar for all sources (0.4-1.5 x 1040 erg s-1).

  1. The link between coherent burst oscillations, burst spectral evolution and accretion state in 4U 1728-34

    CERN Document Server

    Zhang, Guobao; Zamfir, Michael; Cumming, Andrew

    2015-01-01

    Coherent oscillations and the evolution of the X-ray spectrum during thermonuclear X-ray bursts in accreting neutron-star X-ray binaries have been studied intensively but separately. We analysed all the X-ray bursts of the source 4U 1728-34 with the Rossi X-ray Timing Explorer. We found that the presence of burst oscillations can be used to predict the behaviour of the blackbody radius during the cooling phase of the bursts. If a burst shows oscillations, during the cooling phase the blackbody radius remains more or less constant for ~2 - ~8s, whereas in bursts that do not show oscillations the blackbody radius either remains constant for more than ~2 - ~8s or it shows a rapid (faster than ~2s) decrease and increase. Both the presence of burst oscillations and the time-dependent spectral behaviour of the bursts are affected by accretion rate. We also found that the rise time and convexity of the bursts' light curve are different in bursts with and without oscillations in 4U 1728--34. Bursts with oscillations ...

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

    DEFF Research Database (Denmark)

    Pedersen, Morten Gram

    2007-01-01

    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...... cells are subjected to stochastic fluctuations in plasma membrane currents, which are likely to disturb the bursting mechanism and transform medium bursters into spikers or very fast bursters. We present a polynomial, minimal, phantom burster model and show that noise modifies the plateau fraction and...... lowers the burst period dramatically in phantom bursters. It is therefore unlikely that slow bursting in single cells is driven by the slow phantom bursting mechanism, but could instead be driven by oscillations in glycolysis, which we show are stable to random ion channel fluctuations. Moreover, so...

  3. Are gamma-ray bursts cosmological?

    CERN Document Server

    Horvath, I

    2015-01-01

    Gamma-ray burst sources are distributed with a high level of isotropy, which is compatible with either a cosmological origin or an extended Galactic halo origin. The brightness distribution is another indicator used to characterize the spatial distribution in distance. In this paper the author discusses detailed fits of the BATSE gamma-ray burst peak-flux distributions with Friedmann models taking into account possible density evolution and standard candle luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and the author derives the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable

  4. Coherence resonance in bursting neural networks

    Science.gov (United States)

    Kim, June Hoan; Lee, Ho Jun; Min, Cheol Hong; Lee, Kyoung J.

    2015-10-01

    Synchronized neural bursts are one of the most noticeable dynamic features of neural networks, being essential for various phenomena in neuroscience, yet their complex dynamics are not well understood. With extrinsic electrical and optical manipulations on cultured neural networks, we demonstrate that the regularity (or randomness) of burst sequences is in many cases determined by a (few) low-dimensional attractor(s) working under strong neural noise. Moreover, there is an optimal level of noise strength at which the regularity of the interburst interval sequence becomes maximal—a phenomenon of coherence resonance. The experimental observations are successfully reproduced through computer simulations on a well-established neural network model, suggesting that the same phenomena may occur in many in vivo as well as in vitro neural networks.

  5. Environmental Effects of Gamma Ray Bursts

    International Nuclear Information System (INIS)

    Gamma rays bursts, coming from very massive stars, are the most powerful explosions in our Universe. Some authors have linked them to some of the climatic changes and consequent biological mass extinctions of the Phanerozoic eon. However, the consequences of their direct impact on primitive Earth, is today a hot topic of debate. On the other hand, it is usually assumed that they were more common in earlier stages of our galaxy. So it is important to evaluate its potential effects on terrestrial paleoenvironments. We outline some simple models to estimate their influence mainly on the primordial atmospheric chemistry of Earth and on the climate in general. To do that, we consider different scenarios where the atmospheric composition diverges substantially from the atmosphere today, and compute the evolution of principal chemical species under the intense radiational stress of a gamma ray burst. Furthermore, the possible impact on the isotopic composition, geochemistry and the biosphere are mentioned in general way

  6. The Supernova -- Gamma-Ray Burst Connection

    CERN Document Server

    Woosley, S E

    2006-01-01

    Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature's two grandest explosions. We review here the growing evidence for and theoretical implications of this association, and conclude that most long-duration soft-spectrum GRBs are accompanied by massive stellar explosions (GRB-SNe). The kinetic energy and luminosity of well-studied GRB-SNe appear to be greater than those of ordinary SNe, but evidence exists, even in a limited sample, for considerable diversity. The existing sample also suggests that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow. Neither all SNe, nor even all SNe of Type Ibc produce GRBs. The degree of differential rotation in the collapsing iron core of massive stars when they die may be what makes the difference.

  7. Gamma-Ray Burst Prompt Emission

    CERN Document Server

    Zhang, Bing

    2014-01-01

    The origin of gamma-ray burst (GRB) prompt emission, bursts of gamma-rays lasting from shorter than one second to thousands of seconds, remains not fully understood after more than 40 years of observations. The uncertainties lie in several open questions in the GRB physics, including jet composition, energy dissipation mechanism, particle acceleration mechanism, and radiation mechanism. Recent broad-band observations of prompt emission with Fermi sharpen the debates in these areas, which stimulated intense theoretical investigations invoking very different ideas. I will review these debates, and argue that the current data suggest the following picture: A quasi-thermal spectral component originating from the photosphere of the relativistic ejecta has been detected in some GRBs. Even though in some cases (e.g. GRB 090902B) this component dominates the spectrum, in most GRBs, this component either forms a sub-dominant "shoulder" spectral component in the low energy spectral regime of the more dominant "Band" co...

  8. GAMMA-RAY BURSTS, NEW COSMOLOGICAL BEACONS

    Directory of Open Access Journals (Sweden)

    V. Avila-Reese

    2009-01-01

    Full Text Available Long Gamma-Ray Bursts (GRBs are the brightest electromagnetic explosions in the Universe, associated to the death of massive stars. As such, GRBs are potential tracers of the evolution of the cosmic massive star formation, metallicity, and Initial Mass Function. GRBs also proved to be appealing cosmological distance indicators. This opens a unique opportunity to constrain the cosmic expansion history up to redshifts 5-6. A brief review on both subjects is presented here.

  9. Downhole drilling network using burst modulation techniques

    Science.gov (United States)

    Hall; David R. , Fox; Joe

    2007-04-03

    A downhole drilling system is disclosed in one aspect of the present invention as including a drill string and a transmission line integrated into the drill string. Multiple network nodes are installed at selected intervals along the drill string and are adapted to communicate with one another through the transmission line. In order to efficiently allocate the available bandwidth, the network nodes are configured to use any of numerous burst modulation techniques to transmit data.

  10. Identifying crucial parameter correlations maintaining bursting activity.

    Directory of Open Access Journals (Sweden)

    Anca Doloc-Mihu

    2014-06-01

    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.

  11. The Euclidean distribution of Fast Radio Bursts

    OpenAIRE

    Oppermann, Niels; Connor, Liam; Pen, Ue-Li

    2016-01-01

    We investigate whether current data on the distribution of observed flux densities of Fast Radio Bursts (FRBs) are consistent with a constant source density in Euclidean space. We use the number of FRBs detected in two surveys with different characteristics along with the observed signal-to-noise ratios of the detected FRBs in a formalism similar to a V/V_max-test to constrain the distribution of flux densities. We find consistency between the data and a Euclidean distribution. Any extension ...

  12. Gamma Ray Bursts and their Optical Counterparts

    International Nuclear Information System (INIS)

    Gamma Ray Bursts (GRB) have been discovered 38 years ago and still remain one of the most intriguing puzzles of astrophysics. In this paper we remind briefly the history of GRB studies and review the current experimental evidence with the emphasis on GRB optical counterparts. At the end we introduce '' π of the Sky '' project designed to catch prompt optical emission from GRB sources. (author)

  13. Gamma-ray bursts - a critical review

    International Nuclear Information System (INIS)

    We present a short general introduction into the field of gamma-ray bursts (GRBs) research, summarizing the past and the present status. We give an general view of the GRBs observations to date, both in the prompt emission phase as well as in the afterglow phase, and a brief primer into the theory, mainly in the frame-work of the fireball model. (authors)

  14. Classifying running-related injuries based upon etiology, with emphasis on volume and pace

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Oestergaard; Nohr, Ellen Aagaard; Rasmussen, Sten;

    2013-01-01

    develop due to rapidly changing running volume, while others develop due to rapidly changing running pace. DESCRIPTION OF TOPIC WITH RELATED EVIDENCE: Evidence from clinical and experimental studies is presented to support the assertion that rapid change in running volume may lead to the development...... of patellofemoral pain syndrome, iliotibial band syndrome, and patellar tendinopathy, while change in running pace may be associated with the development of achilles tendinopathy, gastrocnemius injuries, and plantar fasciitis. DISCUSSIONRELATION TO CLINICAL PRACTICE: If this assertion is correct, bias may...... be prevented in future studies by categorizing injuries into volume or pacing injuries. However, more work is needed to provide further evidence in support of this approach. Future investigations of the link between training patterns and injury development should be designed as large-scale prospective studies...

  15. Influence of cinnamon and catnip on the stereotypical pacing of oncilla cats (Leopardus tigrinus) in captivity.

    Science.gov (United States)

    Resende, Letícia de S; Pedretti Gomes, Karla C; Andriolo, Artur; Genaro, Gelson; Remy, Gabriella L; Almeida Ramos, Valdir de

    2011-01-01

    Nonhuman animals in captivity can experience environmental privation that results in their exhibiting abnormal behaviors. Environmental enrichment techniques can help improve their welfare. This study investigated the behavior of 8 zoo-housed oncilla cats (Leopardus tigrinus) in response to 2 odors (catnip and cinnamon) introduced individually into the animals' enclosures for 3 consecutive days. Proportion of scans spent engaging in stereotypical pacing were compared before, during, and after treatments. The addition of cinnamon reduced the proportion of pacing during and after enrichment (Wilcoxon: Z = 3.16, p behavior. Catnip appears to have elicited no significant difference in the stereotypic pacing before, during, or after the enrichment (Friedman: X(2) = 2.69; p = .260). The results highlight the potential use of cinnamon as a method of environmental enrichment for small captive-housed cats. PMID:22044295

  16. The Swift Gamma-Ray Burst Mission

    CERN Document Server

    Gehrels, N; Burrows, D N; Chincarini, G L; Cominsky, L R; Giommi, P; Hurley, K C; Marshall, F E; Mason, K O; Mészáros, P; Nousek, J A; Roming, P W A; Wells, A A; White, N E; Team, Swift Science

    2004-01-01

    The Swift mission, scheduled for launch in early 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is the first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts per year and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to determine the origin of GRBs; classify GRBs and search for new types; study the interaction of the ultra-relativistic outflows of GRBs with their surrounding medium; and use GRBs to study the early universe out to z>10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a new-generation wide-field gamma-ray (15-150 keV) detector; a narrow-field X-ray telescope; and a narrow-field UV/optical telescope. Redshift determin...

  17. Supercollapsars and their X-ray Bursts

    CERN Document Server

    Komissarov, S S

    2009-01-01

    The very first stars in the Universe can be very massive, frequently reaching $10^3M_\\odot$. If born in large numbers such massive stars can have strong impact on the subsequent star formation producing strong ionising radiation and contaminating the primordial gas with heavy elements. They would leave behind massive black holes that could act as seeds for growing supermassive black holes of active galactic nuclei. Given the anticipated fast rotation such stars would end their live as supermassive collapsars and drive powerful magnetically-dominated jets. In this letter we investigate the possibility of observing the bursts of high-energy emission similar to the Long Gamma Ray Bursts associated with normal collapsars. We show that during the collapse of supercollapsars, the Blandford-Znajek mechanism can extract up to $10^{56}$erg at a rate of few$\\times10^{52}$erg/s. Due to the higher intrinsic time scale and higher redshift the observed burst duration increases by a factor of $\\simeq 1000$ and can reach one...

  18. Radio flares from gamma-ray bursts

    CERN Document Server

    Kopac, D; Kobayashi, S; Virgili, F J; Harrison, R; Japelj, J; Guidorzi, C; Melandri, A; Gomboc, A

    2015-01-01

    We present predictions of centimeter and millimeter radio emission from reverse shocks in the early afterglows of gamma-ray bursts 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 parametrization 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. (2007) and Melandri et al. (2010) in which the typical frequency of the reverse shock was suggested to lie at radio, rather than optical wavelengths at early times, we show that the brightest and most distinct reverse-shock 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 opt...

  19. Dihydroxyoctadecamonoenoate esters inhibit the neutrophil respiratory burst

    Indian Academy of Sciences (India)

    David Alan Thompson; Bruce D Hammock

    2007-03-01

    The leukotoxins [9(10)- and 12(13)-EpOME] are produced by activated inflammatory leukocytes such as neutrophils. High EpOME levels are observed in disorders such as acute respiratory distress syndrome and in patients with extensive burns. Although the physiological significance of the EpOMEs remains poorly understood, in some systems, the EpOMEs act as a protoxin, with their corresponding epoxide hydrolase metabolites, 9,10- and 12,13-DiHOME, specifically exerting toxicity. Both the EpOMEs and the DiHOMEs were also recently shown to have neutrophil chemotactic activity. We evaluated whether the neutrophil respiratory burst, a surge of oxidant production thought to play an important role in limiting certain bacterial and fungal infections, is modulated by members of the EpOME metabolic pathway. We present evidence that the DiHOMEs suppress the neutrophil respiratory burst by a mechanism distinct from that of respiratory burst inhibitors such as cyclosporin H or lipoxin A4, which inhibit multiple aspects of neutrophil activation.

  20. Gamma-Ray Burst Physics with GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Omodei, N.; /INFN, Pisa

    2006-10-06

    The Gamma-ray Large Area Space Telescope (GLAST) is an international space mission that will study the cosmos in the energy range 10 keV-300 GeV, the upper end of which is one of the last poorly observed region of the celestial electromagnetic spectrum. The ancestor of the GLAST/LAT was the Energetic Gamma Ray Experiment Telescope (EGRET) detector, which flew onboard the Compton Gamma Ray Observatory (CGRO). The amount of information and the step forward that the high energy astrophysics made thanks to its 9 years of observations are impressive. Nevertheless, EGRET uncovered the tip of the iceberg, raising many questions, and it is in the light of EGRET's results that the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope, the Large Area Telescope (LAT) vastly more capable than instruments own previously, as well as a secondary instrument, the GLAST Bursts Monitor, or GBM, to augment the study of gamma-ray bursts. Gamma-Ray Bursts (GRBs) science is one of the most exciting challenges for the GLAST mission, exploring the high energy emission of one of the most intense phenomena in the sky, shading light on various problems: from the acceleration of particles to the emission processes, to more exotic physics like Quantum Gravity effect. In this paper we report the work done so far in the simulation development as well as the study of the LAT sensitivity to GRB.

  1. Bursting emission from B0611+22

    CERN Document Server

    Seymour, Andrew; Ridley, Josh

    2014-01-01

    Over the past decade it has become apparent that a class of `bursting pulsars' exist with the discovery of PSR J1752+2359 and PSR J1938+2213. In these pulsars, a sharp increase in the emission is observed that then tends to systematically drop-off from pulse-to-pulse. In this paper we describe the discovery of such a relationship in high-sensitivity observations of the young (characteristic age of 90,000 yrs) 0.33 s pulsar B0611+22 at both 327 MHz and 1400 MHz with the Arecibo radio telescope. While Nowakowski previously showed that B0611+22 has mode-switching properties, the data presented here show, for the first time, that this pulsar emits bursts with characteristic time-scales of several hundred seconds. At 327 MHz, the pulsar shows steady behaviour in one emission mode which is enhanced by bursting emission slightly offset in pulse phase from this steady emission. Contrastingly at 1400 MHz, the two modes appear to behave in a competing operation while still offset in phase. Using a fluctuation spectrum ...

  2. A Fast Radio Burst Host Galaxy

    CERN Document Server

    Keane, E F; 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

    2016-01-01

    In recent years, millisecond duration radio signals originating from 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. While every fast radio burst has a dispersion measurement, none before now have had a redshift measurement, due to the difficulty in pinpointing their celestial coordinates. Here we present the discovery of a fast radio burst and the identification of a fading radio transient lasting $\\sim 6$ days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be $z=0.492\\pm0.008$. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionised baryons in the intergalactic medium of $\\Omega_{\\mathrm{IGM}}=4.9 \\pm 1.3\\%$, in agreement with the expectation from WMAP, and i...

  3. Composite-flywheel burst-containment study

    Energy Technology Data Exchange (ETDEWEB)

    Sapowith, A D; Handy, W E

    1982-04-08

    A key component impacting total flywheel energy storage system weight is the containment structure. This report addresses the factors that shape this structure and define its design criteria. In addition, containment weight estimates are made for the several composite flywheel designs of interest so that judgements can be made as to the relative weights of their containment structure. The requirements set down for this program were that all containment weight estimates be based on a 1 kWh burst. It should be noted that typical flywheel requirements for regenerative braking of small automobiles call for deliverable energies of 0.25 kWh. This leads to expected maximum burst energies of 0.5 kWh. The flywheels studied are those considered most likely to be carried further for operational design. These area: The pseudo isotropic disk flywheel, sometimes called the alpha ply; the SMC molded disk; either disk with a carbon ring; the subcircular rim with cruciform hub; and Avco's bi-directional circular weave disk. The flywheel materials for the disk are S-glass; the subcircular rim is Kevlar over S-glass. Test data on flywheel bursts and containment failures were analyzed. Recommendations are made for further testing.

  4. Burst fracture of the fifth lumber vertebra

    International Nuclear Information System (INIS)

    Objective: To investigate the stability of the fifth lumber vertebra after burst fracture. Methods: 7 patients with burst fracture of the fifth lumber vertebra were examined by X-ray and CT, and followed for 6-36 months. The changes of wedge index, lordosis, degree of spinal canal stenosis and neurological features were observed during the episode and followed up. Results: The three spinal column structure was disrupted in 6 of 7 patients. The anterior and mid columns were involved in 1 case. Spinal stenosis of first and second degrees was seen in 3 cases, and in one case, there was no spinal canal stenosis. Lower lumber motor-root deficits were found in 2 of 7 patients and resolved in follow up. There was no tendency of progressive collapse of the vertebral body and spinal stenosis. Conclusions: Burst fracture of the fifth lumber vertebra was specific, most of them were stable fractures, although two or three columns of the spine were disrupted and accompanied by spinal canal stenosis

  5. Progress report on case studies carried out within the United Nations Development Programme for Asian Co-operation on Energy and the Environment (PACE-E)

    International Nuclear Information System (INIS)

    The major goal of energy-environmental planning (EEP) in the framework of the Programme for Asian Co-operation on Energy and the Environment (PACE-E) is the enhancement of the environmental perspectives in energy planning and policy making in the developing countries of Asia. Three immediate objectives can be mentioned: (1) the strengthening of energy-environmental databases in Asia; (2) the development and application of innovative and effective energy impact assessment methodologies; and (3) the identification of suitable institutional structure that will result in a more transparent treatment of energy-environmental concerns in national energy plans and in subsectoral (e.g. coal, natural gas) development strategies. In the framework of Programme Element I, three sub-activities, to be executed by the Economic and Social Commission for Asia and the Pacific (ESCAP), have been proposed: the main objective of EEP1 is to strengthen the capacities of the methodologies of survey and sample design and the techniques of data processing. The main objective of EEP2 is to assist in the application of methods and tools of sectoral energy demand analysis and scenario building to evaluate energy conservation and fuel switching potentials. The EEP3 activities will consist of the review and application of methodologies and procedures for integrating environmental considerations into energy planning and policy analysis. The direct recipients of this programme will be policy makers, administrators and technicians from 20 Asian countries dealing with energy and environmental planning and management. The paper presents an overview of the implementation and first results of the various sub-activities of the EEP element of PACE-E executed by ESCAP and implemented by the Energy Planning Central Consultant Team of the Asian Institute of Technology. (author). 18 refs

  6. Effects of ventricular pacing protocol on electrical restitution assessments in guinea-pig heart.

    Science.gov (United States)

    Osadchii, Oleg E

    2012-07-01

    The steep slope of the rate adaptation of ventricular action potential duration (APD) is thought to indicate profibrillatory tendency. In cardiac patients, APD restitution is commonly assessed by extrasystolic (S(1)-S(2)) stimulations rather than dynamic pacing, because the latter may provoke myocardial ischaemia. In this study, ventricular APD and effective refractory period (ERP) were measured in perfused guinea-pig hearts to determine whether S(1)-S(2) stimulations and dynamic pacing may have similar value in APD restitution assessments aimed to predict arrhythmic risk. The maximal restitution slope was greater upon S(1)-S(2) stimulation than dynamic pacing at the epicardium (S(1)-S(2), 1.2 ± 0.08; dynamic, 0.72 ± 0.06; P = 0.0004) and endocardium (S(1)-S(2), 1.45 ± 0.08; dynamic, 0.95 ± 0.06; P = 0.0003). This difference was partly accounted for by an effect of the previous pacing history, as evidenced by flattening of APD restitution upon reductions in the regular beating interval prior to S(2) application. Furthermore, shorter ERP than APD relationships enabled ventricular capture at shorter diastolic intervals during S(1)-S(2) stimulation than dynamic pacing at the epicardium (S(1)-S(2), -1 ± 3 ms; dynamic, 35 ± 3 ms; P early premature beats (diastolic interval of ∼0 ms), thereby flattening the S(1)-S(2) restitution curve, but had no effect on dynamic restitution. In hypokalaemia-induced arrhythmogenicity, a reduction in ventricular fibrillation threshold was paralleled by increased steepness of dynamic APD restitution, while no change in the maximal restitution slope was revealed by S(1)-S(2) stimulations. In summary, changes in electrical restitution obtained from extrasystolic stimulations may dissociate from those revealed by dynamic pacing. These findings therefore challenge the value of electrical restitution assessments based on extrasystolic stimulation alone, as commonly performed in the clinical setting. PMID:22447974

  7. Temporary epicardial left ventricular and biventricular pacing improves cardiac output after cardiopulmonary bypass

    Directory of Open Access Journals (Sweden)

    García-Bengochea Jose B

    2012-10-01

    Full Text Available Abstract Background To evaluate, with different pacing modes, acute changes in left ventricular systolic function, obtained by continuous cardiac output thermodilution in various subsets of patients undergoing cardiopulmonary bypass surgery. Increments of mean arterial pressure and cardiac output were considered the end point. Methods Fifty cases electively submitted to cardiac surgery were analyzed. Isolated valve surgery 62%, coronary revascularization 30% and 8% mixed disease. Left ventricular ejection fraction was preserved in 50%,36% had moderate depression,(EF 36%-50% whereas 14% had severe depression (EF  Results Right atrium-right ventricular pacing, decreased significantly mean arterial pressure and cardiac output (2.3% in the overall population and in the subgroups studied. Right atrium-left ventricle, increased mean arterial pressure and cardiac output in 79% of patients and yielded cardiac output increments of 7.5% (0.40 l/m in the low ejection fraction subgroup and 7.3% (0.43 l/m in the left bundle branch block subset. In atrial fibrillation patients, left ventricular and biventricular pacing produced a significant increase in cardiac output 8.5% (0.39 l/min and 11.6% (0.53 l/min respectively. The dP/dt max increased significantly with both modes (p = 0.021,p = 0.028. Conclusion Right atrial-right ventricular pacing generated adverse hemodynamic effects. Right atrium-left ventricular pacing produced significant CO improvement particularly in cases with depressed ventricular function and left bundle branch block. The greatest increments were observed with left ventricular or biventricular pacing in atrial fibrillation with depressed ejection fraction.

  8. UWB multi-burst transmit driver for averaging receivers

    Science.gov (United States)

    Dallum, Gregory E

    2012-11-20

    A multi-burst transmitter for ultra-wideband (UWB) communication systems generates a sequence of precisely spaced RF bursts from a single trigger event. There are two oscillators in the transmitter circuit, a gated burst rate oscillator and a gated RF burst or RF power output oscillator. The burst rate oscillator produces a relatively low frequency, i.e., MHz, square wave output for a selected transmit cycle, and drives the RF burst oscillator, which produces RF bursts of much higher frequency, i.e., GHz, during the transmit cycle. The frequency of the burst rate oscillator sets the spacing of the RF burst packets. The first oscillator output passes through a bias driver to the second oscillator. The bias driver conditions, e.g., level shifts, the signal from the first oscillator for input into the second oscillator, and also controls the length of each RF burst. A trigger pulse actuates a timing circuit, formed of a flip-flop and associated reset time delay circuit, that controls the operation of the first oscillator, i.e., how long it oscillates (which defines the transmit cycle).

  9. [Influence of development pace on pharyngeal teeth formula in Abramis brama (L.) bream: experimental data].

    Science.gov (United States)

    Bolotovskii, A A; Levin, B A

    2011-01-01

    An experiment on acceleration and retardation of ontogenesis with thyroid manipulation has revealed direct changes in definitive dentition of pharyngeal bones in Abramis brama bream. As development pace accelerates, the number of teeth reduces to the formula 5-4. When development pace slows down, this number increases to the formula 6-5. Moreover, an additional minor row of teeth (1.6-5.1, 2.6-5.2) is formed. The observed changes transcend typical changes happening in nature. It is assumed that heterochronies provoke changes in the number of teeth. PMID:21786649

  10. MCTS self-paced training kit (exam 70-680) configuring Windows 7

    CERN Document Server

    McLean, Ian

    2010-01-01

    NOTE: The most recent printings of this title incorporate corrections to errors found in the earlier printings. This Self-Paced Training Kit is designed to help maximize your performance on 70-680, the required exam for the Microsoft® Certified Technology Specialist (MCTS): Windows 7, Configuration certification.This 2-in-1 kit includes the official Microsoft study guide, plus practice tests on CD to help you assess your skills. It comes packed with the tools and features exam candidates want most-including in-depth, self-paced training based on final exam content; rigorous, objective-by-obj

  11. Trame di Pace. Simboli, carte, azioni di un’utopia possibile. 1945-2003

    OpenAIRE

    Nadia Baiesi; Gianluca Gabrielli; Elda Guerra; Rossella Ropa

    2014-01-01

    La mostra racconta la storia degli uomini e delle donne che hanno ragionato di pace non più come di una nobile speranza, ma come dell’unica chance di salvezza per l’umanità. La scansione cronologica, per decenni, parte dal 1945 e arriva al 2003 con la diffusione della bandiera arcobaleno in occasione della campagna «Pace da tutti i balconi», nata per scongiurare il secondo conflitto in Iraq. Al centro della mostra un percorso sui simboli che sono stati in...

  12. Dual-Chamber Pacing for Cardiac Arrhythmias: Controversies in Cloning the Conduction System

    OpenAIRE

    Parsonnet, Victor; Bernstein, Alan D.; Norman, John C.

    1984-01-01

    From the outset, the art and science of cardiac pacing has been beset with a variety of problems. With the passage of time and concentrated effort in the interrelated sciences, many have been solved. We no longer are concerned with premature battery failure or leaking pulse-generator capsules, but now focus on an entirely new set of issues that beg for resolution. Foremost among these is the true role of dual-chamber pacing in the treatment of slow and fast cardiac arrhythmias of a multitude ...

  13. Pacing Lead-Induced Granuloma in the Atrium: A Foreign Body Reaction to Polyurethane

    Directory of Open Access Journals (Sweden)

    Shinagawa Yoko

    2013-01-01

    Full Text Available We described a case of an 82-year-old male who presented with a granuloma entrapping the polyurethane-coated pacing lead at the site of contact on the atrium. He had been paced for 8 years without symptoms or signs suggestive of an allergic reaction to the pacemaker system and died from thrombosis of the superior mesenteric artery and heart failure. A histological examination of the nodule showed an incidental granuloma with multinucleated giant cells. No granuloma was found in the heart or the lung.

  14. First Observation Of ELM Pacing With Vertical Jogs In A Spherical Torus

    Energy Technology Data Exchange (ETDEWEB)

    Gerhardt, S P; Canik, J M; Maingi, R; Bell, R; Gates, d; Goldston, R; Hawryluk, R; Le Blanc, B P; Menard, J; Sontag, A C; Sabbagh, S

    2010-07-15

    Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies. __________________________________________________

  15. The effects of presentation pace and modality on learning a multimedia science lesson

    Science.gov (United States)

    Chung, Wen-Hung

    Working memory is a system that consists of multiple components. The visuospatial sketchpad is the main entrance for visual and spatial information, whereas acoustic and verbal information is processed in the phonological loop. The central executive works as a coordinator of information from these two subsystems. Numerous studies have shown that working memory has a very limited capacity. Based on these characteristics of working memory, theories such as cognitive load theory and the cognitive theory of multimedia learning provide multimedia design principles. One of these principles is that when verbal information accompanying pictures is presented in audio mode instead of visually, learning can be more effective than if both text and pictures are presented visually. This is called the modality effect. However, some studies have found that the modality effect does not occur in some situations. In most experiments examining the modality effect, the multimedia is presented as system-paced. If learners are able to repeat listening as many times as they need, the superiority of spoken text over visual text seems lessened. One aim of this study was to examine the modality effect in a learner-controlled condition. This study also used the one-word-at-a-time technique to investigate whether the modality effect would still occur if both reading and listening rates were equal. There were 182 college students recruited for this study. Participants were randomly assigned to seven groups: a self-paced listening group, a self-paced reading group, a self text-block reading group, a general-paced listening group, a general-paced reading group, a fast-paced listening group, and a fast-paced reading group. The experimental material was a cardiovascular multimedia module. A three-by-two between-subjects design was used to test the main effect. Results showed that modality effect was still present but not between the self-paced listening group and the self text-block reading group

  16. International piping benchmarks: use of the simplified code PACE 2. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, J.T.; Spence, J. (University of Strathclyde (United Kingdom)); Blundell, C. (Risley Nuclear Power Development Establishment, Central Technical Services, Risley, Warrington (United Kingdom)) (ed.)

    1979-05-15

    This report compares the results obtained using the code PACE 2 with the International Working Group on Fast Reactors (IWGFR) International Piping Benchmark solutions. PACE 2 is designed to analyse systems of pipework using a simplified method which is economical of computer time and hence inexpensive. This low cost is not achieved without some loss of accuracy in the solution, but for most parts of a system this inaccuracy is acceptable and those sections of particular importance may be reanalysed using more precise methods in order to produce a satisfactory analysis of the complete system at reasonable cost.

  17. The Fermi-GBM X-ray burst monitor: thermonuclear bursts from 4U 0614+09

    CERN Document Server

    Linares, M; Jenke, P; van der Horst, A J; Camero-Arranz, A; Kouveliotou, C; Chakrabarty, D; Beklen, E; Bhat, P N; Briggs, M S; Finger, M; Paciesas, W; Preece, R; von Kienlin, A; Wilson-Hodge, C A

    2012-01-01

    Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the neutron star interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor (GBM) aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09, when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12+/-3 d (68% confidence interval) between March 2010 and March 2011, classified all bursts as normal duration bursts and placed a lower limit on the recurrence time of long/intermediate bursts of 62 d (95% confidence level). We discuss how observations of thermonuclear bursts in the hard X-ray band compare to pointed soft X-ray observations, and quantify such bandpass effects on measurements of burst radiated energy and duration. We put our results for 4U 0614+09 in the context of other bu...

  18. Upper-Bound Performance of a Wideband Burst-by-Burst Adaptive Modem

    OpenAIRE

    Wong, C. H.; Hanzo, L.

    1999-01-01

    In this contribution, adaptive modulation is applied in conjunction with a Decision Feedback Equalizer (DFE) in order to mitigate the effects of the slowly varying wideband multi-path Rayleigh fading channel. The upper-bound mean BER and Bits Per Symbol (BPS) performance of this scheme is determined by utilizing the pseudo-SNR at the output of the DFE, in order to switch the modulation schemes on a burst-by-burst basis. The performances of each individual modulation schemes and their amalgama...

  19. Implications of fast radio bursts for superconducting cosmic strings

    International Nuclear Information System (INIS)

    Highly beamed, short-duration electromagnetic bursts could be produced by superconducting cosmic string (SCS) loops oscillating in cosmic magnetic fields. We demonstrated that the basic characteristics of SCS bursts such as the electromagnetic frequency and the energy release could be consistently exhibited in the recently discovered fast radio bursts (FRBs). Moreover, it is first showed that the redshift distribution of the FRBs can also be well accounted for by the SCS burst model. Such agreements between the FRBs and SCS bursts suggest that the FRBs could originate from SCS bursts and thus they could provide an effective probe to study SCSs. The obtained values of model parameters indicate that the loops generating the FRBs have a small length scale and they are mostly formed in the radiation-dominated cosmological epoch

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    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. The...... derived positions of the bursts are reported. Additionally, most of the events have been confirmed by coincident detections with instruments on other spacecrafts. The features of two of the bursts and the results of searches for related events in the optical are described....

  1. 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...... 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...... events lasting more than a few minutes. Of special interest are exceptional X-ray bursts which duration about a few tens of minutes is intermediate between usual short bursts and hour long superbursts. The processes driving such long bursts are not yet fully understood: depending on the composition of...

  2. Power Density Spectra of $\\gamma$-Ray Bursts

    CERN Document Server

    Beloborodov, A M

    1999-01-01

    Power density spectra (PDSs) of long gamma-ray bursts provide useful information on GRBs, indicating their self-similar temporal structure. The best power-law PDSs are displayed by the longest bursts (T_90 > 100 s) in which the range of self-similar time scales covers more than 2 decades. Shorter bursts have apparent PDS slopes more strongly affected by statistical fluctuations. The underlying power law can then be reproduced with high accuracy by averaging the PDSs for a large sample of bursts. This power-law has a slope alpha\\approx -5/3 and a sharp break at 1 Hz. The power-law PDS provides a new sensitive tool for studies of gamma-ray bursts. In particular, we calculate the PDSs of bright bursts in separate energy channels. The PDS flattens in the hard channel (h\

  3. Burst suppression electroencephalogram with mushroom poisoning, Amanita pantherina

    OpenAIRE

    Yuka Ogawa; Hiromasa Sato; Motoyoshi Yamamoto; Hiroyuki Tada; Takao Hashimoto

    2015-01-01

    We report on a patient with Amanita pantherina poisoning who showed a burst suppression pattern on electroencephalography during a comatose state. The patient recovered without sequelae a week after ingestion. Burst suppression pattern is defined as alternating bursts and periods of electrical silence, and it is associated with comatose states of various causes. The major toxins contained in A. pantherina are ibotenic acid, an excitatory amino acid at the glutamate receptors, and muscimol, an...

  4. Burst Fractures as a Result of Attempted Suicide by Jumping

    OpenAIRE

    Kim, Do Young; Choi, Hong June; Park, Jeong Yoon; Kim, Kyung Hyun; Kuh, Sung Uk; Chin, Dong Kyu; Kim, Keun Su; Cho, Yong Eun; Jin, Byoung Ho

    2014-01-01

    Objective Jumping from high place for the purpose of suicide results in various damages to body area. A burst fracture of vertebrae is representative of them and we reviewed eight patients who were diagnosed with spinal burst fracture following suicide falling-down. The demographics, characteristics, performed operation, combined injuries, psychological past histories of the patients were analyzed. Methods A retrospective study was made of patients who are diagnosed with vertebral burst fract...

  5. Strain bursts in plastically deforming Molybdenum micro- and nanopillars

    OpenAIRE

    Zaiser, Michael; Schwerdtfeger, Jan; Schneider, Andreas; Frick, Carl; Clark, Blythe Gore; Gruber, Patric; Arzt, Eduard

    2009-01-01

    Abstract Plastic deformation of micron and sub-micron scale specimens is characterized by intermittent sequences of large strain bursts (dislocation avalanches) which are separated by regions of near-elastic loading. In the present investigation we perform a statistical characterization of strain bursts observed in stress-controlled compressive deformation of monocrystalline molybdenum micropillars. We characterize the bursts in terms of the associated elongation increments and pea...

  6. Detecting Pipe Bursts Using Heuristic and CUSUM Methods

    OpenAIRE

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

    2014-01-01

    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. Full System Bifurcation Analysis of Endocrine Bursting Models

    OpenAIRE

    Rieß, Thorsten; Sherman, Arthur; Tsaneva-Atanasova, KT; Osinga, HM

    2010-01-01

    Plateau bursting is typical of many electrically excitable cells, such as endocrine cells that secrete hormones and some types of neurons that secrete neurotransmitters. Although in many of these cell types the bursting patterns are regulated by the interplay between voltage-gated calcium channels and calcium-sensitive potassium channels, they can be very different. For example, in insulin-secreting pancreatic β-cells, plateau bursting is characterized by well-defined spikes during the depola...

  8. Are designers making the most of new bursting disc devices

    International Nuclear Information System (INIS)

    Recent years have seen significant advances in the technology of bursting discs for protecting plants against excess pressure. The recently developed scored reverse buckling discs burst within an accuracy of +- 3 percent. Also the pressure can rise to 90 percent of the disc's minimum burst pressure without affecting its performance. It is argued that it would now be a desirable feature in modern PWRs to update rupture disc design. (author)

  9. Effects of wind application on thermal perception and self-paced performance

    NARCIS (Netherlands)

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

    2013-01-01

    Physiological and perceptual effects of wind cooling are often intertwined and have scarcely been studied in self-paced exercise. Therefore, we aimed to investigate (1) the independent perceptual effect of wind cooling and its impact on performance and (2) the responses to temporary wind cooling dur

  10. Respiratory muscle pacing with chronically implanted intramuscular Permaloc electrodes: A feasibility study

    Directory of Open Access Journals (Sweden)

    James S. Walter, PhD

    2011-02-01

    Full Text Available We tested the feasibility of stimulating upper-intercostal and abdominal muscles plus the diaphragm by using chronically implanted intramuscular electrodes. During two survival surgeries with six dogs, intramuscular electrodes were implanted bilaterally in the three respiratory muscles. Standard stimulation of the diaphragm was conducted. The dorsolateral and ventrolateral abdominal wall areas were stimulated with a 25 mA current. The second to fourth intercostal spaces were stimulated to elicit the largest tidal volume associated with the least coactivation of the serratus and latissimus muscles. Lone diaphragm and upper-intercostal muscle pacing produced inhaled tidal volumes (mean +/- standard error of the mean of 293 +/- 36 mL and 59 +/- 17 mL, respectively. Lone abdominal muscle pacing produced an exhaled volume of 55 +/- 17 mL. Combined pacing of diaphragm and intercostal muscles increased the inhaled volume to 389 +/- 39 mL. The addition of abdominal pacing following the combined stimulation of diaphragm and intercostals increased the exhaled volume to 472 +/- 54 mL. During autopsy, dislodgement of the electrodes overlying the ribs was a concern and probably resulted from loose animal jackets. Chronic intramuscular Permaloc electrodes can be implanted in several respiratory muscles and increase tidal volumes more than diaphragm stimulation alone.

  11. Automated Apprenticeship Training (AAT). A Systematized Audio-Visual Approach to Self-Paced Job Training.

    Science.gov (United States)

    Pieper, William J.; And Others

    Two Automated Apprenticeship Training (AAT) courses were developed for Air Force Security Police Law Enforcement and Security specialists. The AAT was a systematized audio-visual approach to self-paced job training employing an easily operated teaching device. AAT courses were job specific and based on a behavioral task analysis of the two…

  12. Self-Paced Instruction in Biometry at the University of Texas School of Public Health.

    Science.gov (United States)

    Harrist, Ronald B.; And Others

    Among students of public health, there is a wide variation of aptitude, preparation, and motivation for the study of biometry. Self-paced instruction offers a way to deal with problems arising from such diversity. The Proctorial System of Instruction (PSI) as described by Keller was used to present two elementary biometry courses. Although there…

  13. Effect of heat and heat acclimatization on cycling time trial performance and pacing

    DEFF Research Database (Denmark)

    Racinais, Sebastien; Périard, Julien D; Karlsen, Anders;

    2015-01-01

    PURPOSE: To determine the effects of heat-acclimatization on performance and pacing during outdoor cycling time-trials (TT, 43.4km) in the heat. METHODS: Nine cyclists performed 3 TTs in hot ambient conditions (TTH, ∼37ºC) on the first (TTH-1), sixth (TTH-2) and fourteenth (TTH-3) days of training...

  14. The Effects of TV Program Pacing on the Behavior of Preschool Children

    Science.gov (United States)

    Anderson, Daniel R.; And Others

    1977-01-01

    Assertions that television (Sesame Street in particular) produces hyperactivity, impulsivity, disorganized behavior, and shortened attention spans in pre-school children were investigated. No evidence was found that rapid television pacing has an immediate negative impact on behavior of preschool children. (Author/STS)

  15. Molecular mechanisms of early atrial remodeling by rapid atrial pacing in rabbits

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective: To establish a rabbit atrial fibrillation model with rapid atrial pacing (RAP) and investigate its ultrastructural changes and expressions of L-type calcium channel subunits and potassium channel Ky4.3. Methods: Thirty-six rabbits were performed electrical stimulation through bipolar endocardial led by surgical technique, 600 beat per min from 0 to 48 h. Atrial ultrastructure was observed by transmission electron microscope (TEM) after different pacing times. mRNA were measured by reverse transcription-polymerase chain reaction (RT-PCR). Results: Atrial ultrastructure had alteration after 3 hours' pacing, such as mitochondria vacuolization, myofilament lysis and glucogen aggregation. The mRNA of the Ca2+ channel β1 and α1 subunits began to decrease after pacing of 6 h, which were paralleled with the change of Kv4.3 mRNA. But the auxiliary subunit α2 were not affected. Conclusion: Ultrastructural changes and mRNA levels of L-type calcium channel subunits and potassium channel Kv4.3 are decreased after RAP, with a mechanism of transcriptional down-regulation of underlying ion channels due to calcium overloading after RAP.

  16. Diagnostic accuracy of metronome-paced tachypnea to detect dynamic hyperinflation

    NARCIS (Netherlands)

    Lahaije, A.J.M.C.; Willems, L.M.; Hees, H.W. van; Dekhuijzen, P.N.R.; Helvoort, H.A.C. van; Heijdra, Y.F.

    2013-01-01

    INTRODUCTION: This prospective study was carried out to investigate if metronome-paced tachypnea (MPT) can serve as an accurate diagnostic tool to identify patients with chronic obstructive pulmonary disease (COPD) who are susceptible to develop dynamic hyperinflation during exercise. Commonly, this

  17. Self-Pacing a Gross Motor Skills Course: Crawler Tractor Operator, MOS 62E20.

    Science.gov (United States)

    Brennan, Mark F.; Taylor, John E.

    As part of the Army's emphasis on performance-oriented instruction in training centers, a study was conducted to determine the feasibility of using self-paced instruction in a gross motor skills course. The Crawler Tractor Operator Course, a seven-week heavy equipment course conducted at Fort Leonard Wood, Missouri was selected for the study…

  18. Cross-sectional Association between Walking Pace and Sleep-disordered Breathing.

    Science.gov (United States)

    Suri, S V; Batterham, A M; Ells, L; Danjoux, G; Atkinson, G

    2015-10-01

    Sleep-disordered breathing is an important comorbidity for several diseases, including stroke. Initial screening tools comprise simple yes/no questions about known risk factors for sleep-disordered breathing, e.g., obesity, sex. But walking speed has not been investigated in this context. We examined the cross-sectional association between walking pace and sleep-disordered breathing in the population-level Multi-Ethnic Study of Atherosclerosis. A sample of 2912 men and 3213 women (46-87 years) reported perceived walking pace outside their homes. A walking pacesleep apnoea (3.5%), self-reported apnoeas (8.4%), loud snoring (20.5%), daytime tiredness (22.2%) and slow-walking pace (26.9%). The 95% CI risk differences (multivariable-adjusted) for slow vs. faster walking pace were; sleep apnoea (0.4-2.5%), self-reported apnoeas (0.1-3.8%), loud snoring (1.2-8.3%), and daytime tiredness (3.0-7.8%). Risk differences were similar between sexes. The multivariable-adjusted risk ratio indicated that slower walkers had 1.5 (95% CI: 1.0 to 2.1) times the risk of sleep apnoea vs. faster walkers. In conclusion, a slower walking speed was associated with a greater prevalence of sleep-disordered breathing, independently from other common screening factors. Therefore, a simple walking speed question may help consolidate screening for this disorder. PMID:26090878

  19. Short Term Auditory Pacing Changes Dual Motor Task Coordination in Children with and without Dyslexia

    Science.gov (United States)

    Getchell, Nancy; Mackenzie, Samuel J.; Marmon, Adam R.

    2010-01-01

    This study examined the effect of short-term auditory pacing practice on dual motor task performance in children with and without dyslexia. Groups included dyslexic with Movement Assessment Battery for Children (MABC) scores greater than 15th percentile (D_HIGH, n = 18; mean age 9.89 [plus or minus] 2.0 years), dyslexic with MABC [less than or…

  20. Managing the Finances. PACE Revised. Level 2. Unit 16. Research & Development Series No. 240BB16.

    Science.gov (United States)

    Ashmore, M. Catherine; Pritz, Sandra G.

    This unit on managing the finances of a small business, the 16th in a series of 18 modules, is on the second level of the revised PACE (Program for Acquiring Competence in Entrepreneurship) comprehensive curriculum. Geared to advanced secondary and beginning postsecondary or adult students, the modules provide an opportunity to learn about and try…

  1. Increased diagnostic contribution of heart rate variability at 0.1Hz paced breathing

    Czech Academy of Sciences Publication Activity Database

    Jurák, Pavel; Halámek, Josef; Somers, V. K.; Nykodým, J.; Leinveber, P.; Fráňa, P.; Eisenberger, M.; Kára, T.

    2005-01-01

    Roč. 4, č. 1 (2005), s. 95. [World Congress on Heart Disease - New Trends in Research, Diagnosis and Treatment /12./. 16.07.2005-19.07.2005, Vancouver] R&D Projects: GA ČR(CZ) GA102/05/0402 Keywords : paced breathing * HRV * ICD Subject RIV: FS - Medical Facilities ; Equipment

  2. Investigating the Effects of Concurrent Performance of Physical and Cognitive Demanding Task in Paced Assembly Lines

    Directory of Open Access Journals (Sweden)

    Shakil Ahmed Shaikh

    2013-07-01

    Full Text Available The study was undertaken to investigate the effects of pacing on aspects of performance at an assembly task and on the operators' responses related to work behaviour, perceived workload and perceived stress. A particular objective of the study was to investigate whether physical and cognitive demands may interact in their influences on these effects. An assembly task was simulated in the laboratory and the level of pacing imposed, work height and memory load within the task were all varied. The results showed that the type of pacing commonly imposed (as is common with a lean manufacturing Takt time system in industry can significantly affect both performance and perceived workload and stress. Physical demands (through work height affecting posture and mental demand (through memory load were also found to have significant effects, as would be expected from the many studies of these in the literature. More importantly, some interactions were found between pacing and work height in their effects on quality of assembly and the operator's own rating of performance, and between work height and memory load in their effects on errors. These findings will need to be taken into account by companies when implementing Takt time systems.

  3. Modeling Pacing Behavior and Test Speededness Using Latent Growth Curve Models

    Science.gov (United States)

    Kahraman, Nilufer; Cuddy, Monica M.; Clauser, Brian E.

    2013-01-01

    This research explores the usefulness of latent growth curve modeling in the study of pacing behavior and test speededness. Examinee response times from a high-stakes, computerized examination, collected before and after the examination was subjected to a timing change, were analyzed using a series of latent growth curve models to detect…

  4. Managing after-work stress: paced breathing while watching video content (abstract)

    NARCIS (Netherlands)

    Tijs, T.J.W.; Weda, J.; Weffers-Albu, M.A.; Hoogenstraaten, W.

    2011-01-01

    Objectives. After a hard day’s work, we need to recover from work stress. Two frequently reported activities to relieve stress are television (TV) watching and paced breathing exercises. We investigated the potential of combining these techniques. Method. Two explorativeexperiments were conducted.

  5. Energy sources in gamma-ray burst models

    Science.gov (United States)

    Taam, Ronald E.

    1987-01-01

    The current status of energy sources in models of gamma-ray bursts is examined. Special emphasis is placed on the thermonuclear flash model which has been the most developed model to date. Although there is no generally accepted model, if the site for the gamma-ray burst is on a strongly magnetized neutron star, the thermonuclear model can qualitatively explain the energetics of some, but probably not all burst events. The critical issues that may differentiate between the possible sources of energy for gamma-ray bursts are listed and briefly discussed.

  6. Gamma-ray burst interaction with dense interstellar medium

    OpenAIRE

    Barkov, Maxim; Bisnovatyi-Kogan, Gennady

    2004-01-01

    Interaction of cosmological gamma ray burst radiation with the dense interstellar medium of host galaxy is considered. Gas dynamical motion of interstellar medium driven by gamma ray burst is investigated in 2D approximation for different initial density distributions of host galaxy matter and different total energy of gamma ray burst. The maximum velocity of motion of interstellar medium is $1.8\\cdot10^4$ km/s. Light curves of gamma ray burst afterglow are calculated for set of non homogeneo...

  7. Broad-band solar bursts of the spike type

    International Nuclear Information System (INIS)

    Observations of high-resolution dynamic spectra of solar broad-band spike bursts (BSB), consisting of the instantaneous brightening of the continuum in the entire spectrograph range of 175-235 MHz, are reported. In noise storms events of the BSB type are rarely encountered and have the form of individual bursts with an average duration of 0.1-0.2 sec or groups of such bursts connected with type III bursts at lower frequencies. Series of aperiodic BSB structures unconnected with type III bursts and observed together with one-second pulsations and fiber bursts, predominate in type IV bursts. In noise storms BSB bursts can be emitted by electrons accelerated instantaneously as a result of the reconnection of magnetic fields, both in a small source (about 10 to the 8th cm) with a broad velocity dispersion and in an extended source (about 5 x 10 to the 9th cm). Structures of the BSB type in type IV bursts may be the result of the scattering of Langmuir waves on whistlers in a large height range. 30 references

  8. Broad-band solar bursts of the spike type

    Energy Technology Data Exchange (ETDEWEB)

    Bakunin, L.M.; Chernov, G.P.

    1985-10-01

    Observations of high-resolution dynamic spectra of solar broad-band spike bursts (BSB), consisting of the instantaneous brightening of the continuum in the entire spectrograph range of 175-235 MHz, are reported. In noise storms events of the BSB type are rarely encountered and have the form of individual bursts with an average duration of 0.1-0.2 sec or groups of such bursts connected with type III bursts at lower frequencies. Series of aperiodic BSB structures unconnected with type III bursts and observed together with one-second pulsations and fiber bursts, predominate in type IV bursts. In noise storms BSB bursts can be emitted by electrons accelerated instantaneously as a result of the reconnection of magnetic fields, both in a small source (about 10 to the 8th cm) with a broad velocity dispersion and in an extended source (about 5 x 10 to the 9th cm). Structures of the BSB type in type IV bursts may be the result of the scattering of Langmuir waves on whistlers in a large height range. 30 references.

  9. The Fermi-GBM X-ray burst monitor

    Science.gov (United States)

    Linares, M.; Fermi GBM X-ray Burst Collaboration

    2010-12-01

    We discuss the first results of the Fermi-GBM all-sky search for X-ray bursts. The very large field of view and X-ray response of the Fermi-GBM make it a unique instrument to study rare, bright and short-lived X-ray bursts. We are performing a systematic search that exploits such capabilities. We present results on long/intermediate type I X-ray bursts, an unusual kind of thermonuclear bursts from accreting neutron stars, and show how Fermi-GBM is giving for the first time robust measurements of their recurrence time.

  10. 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....... Of special interest are low luminosity bursting sources that exhibit X-ray bursts of very different durations allowing to study the transition from a hydrogen-rich bursting regime to a pure helium regime and from helium burning to carbon burning. I will present results obtained from INTEGRAL archive...

  11. Observations of the structure of Type IIIb radio bursts

    International Nuclear Information System (INIS)

    The authors have observed short duration, narrow band Type IIIb radio bursts that occur just before the onset of a normal Type III burst. These observations were made with a multichannel radiometer with a center frequency of 25 MHz, time constant of 10 milliseconds and frequency resolution of 100 KHz. The average half power duration of a typical element of a Type III burst was determined. It was found to be very similar to the time profile of a normal Type III burst, i.e., sharp rise and exponential type decay. (Auth.)

  12. Percussion drilling of metals using bursts of nanosecond pulses.

    Science.gov (United States)

    Hendow, Sami T; Romero, Rosa; Shakir, Sami A; Guerreiro, Paulo T

    2011-05-23

    The effect of ns bursting on percussion drilling of metal is investigated experimentally and analytically, and compared with the efficiency and quality of drilling using single ns pulses. Key advantages are demonstrated, correlating well with the results from a thermal theoretical model. The 1064 nm bursts contain up to 14 pulses of various pulse widths and spacing, and at frequencies of tens of MHz within the burst. The individual pulses have pulse widths of 10 to 200 ns, and up to 12 kW peak power. Burst repetition frequency is single shot to 500 kHz. PMID:21643280

  13. Statistical properties of SGR 1900+14 bursts

    CERN Document Server

    Gogus, E; Kouveliotou, C; Van Paradijs, J; Briggs, M S; Duncan, R C; Thompson, C; Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; Paradijs, Jan van; Briggs, Michael S.; Duncan, Robert C.; Thompson, Christopher

    1999-01-01

    We study the statistics of soft gamma repeater (SGR) bursts, using a data base of 187 events detected with BATSE and 837 events detected with RXTE PCA, all from SGR 1900+14 during its 1998-1999 active phase. We find that the fluence or energy distribution of bursts is consistent with a power law of index 1.66, over 4 orders of magnitude. This scale-free distribution resembles the Gutenberg-Richter Law for earthquakes, and gives evidence for self-organized criticality in SGRs. The distribution of time intervals between successive bursts from SGR 1900+14 is consistent with a log-normal distribution. There is no correlation between burst intensity and the waiting times till the next burst, but there is some evidence for a correlation between burst intensity and the time elapsed since the previous burst. We also find a correlation between the duration and the energy of the bursts, but with significant scatter. In all these statistical properties, SGR bursts resemble earthquakes and solar flares more closely than ...

  14. The First Swift BAT Gamma-Ray Burst Catalog

    OpenAIRE

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

    2007-01-01

    We present the first Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts (GRBs), which contains bursts detected by the BAT between 2004 December 19 and 2007 June 16. This catalog (hereafter BAT1 catalog) contains burst trigger time, location, 90% error radius, duration, fluence, peak flux, and time averaged spectral parameters for each of 237 GRBs, as measured by the BAT. The BAT-determined position reported here is within 1.75' of the Swift X-ray Telescope (XRT)-determined position...

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

    International Nuclear Information System (INIS)

    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

  16. ESTIMATION OF THE BURST LENGTH IN OBS NETWORKS

    OpenAIRE

    Pallavi S.; M. Lakshmi

    2014-01-01

    This paper presents an overview of the optical burst switching (OBS) and discusses the major components. In OBS, the length of the burst arriving at a particular node is unknown, and hence, node design is very complex. In OBS first control, packet is transmitted and reserve the path as in circuit switching, thereafter, the data bursts is transmitted. In this paper, a poisson arrival of packets is considered and estimation is made on the size of the burst length. The results presented in the p...

  17. Coupled hydro-neutronic calculations for fast burst reactor accidents

    International Nuclear Information System (INIS)

    Methods are described for determining the fully coupled neutronic/hydrodynamic response of fast burst reactors (FBR) under disruptive accident conditions. Two code systems, PAD (1 -D Lagrangian) and NIKE-PAGOSA (3-D Eulerian) were used to accomplish this. This is in contrast to the typical methodology that computes these responses by either single point kinetics or in a decoupled manner. This methodology is enabled by the use of modem supercomputers (CM-200). Two examples of this capability are presented: an unreflected metal fast burst assembly, and a reflected fast burst assembly typical of the Skua or SPR-III class of fast burst reactor

  18. Entrapment of a Pacing Lead within a Chiari Network: Utility of Intracardiac Echo and a Laser Sheath.

    Science.gov (United States)

    Aung, Htin; Espinosa, Raul E; Powell, Brian D; McLeod, Christopher J

    2016-06-01

    Although rare, Chiari networks are elaborate embryological remnants that can pose distinct challenges for catheter and pacing lead manipulation within the right atrium. Device entrapment may require open thoracotomy for removal, with significant morbidity. We report an unusual case of pacing lead entanglement within this structure, followed by prompt intracardiac echocardiographic identification and laser sheath removal. PMID:26873294

  19. Heart failure in patients with sick sinus syndrome treated with single lead atrial or dual-chamber pacing:

    DEFF Research Database (Denmark)

    Riahi, Sam; Nielsen, Jens Cosedis; Hjortshøj, Søren; Thomsen, Poul Erik B; Højberg, Søren; Møller, Mogens; Dalsgaard, Dorthe; Nielsen, Tonny; Asklund, Mogens; Friis, Elsebeth V; Christensen, Per Dahl; Simonsen, E. H.; Eriksen, Ulrik H; Jensen, G. V.; Svendsen, Jesper H; Toff, William D; Healey, Jeffrey S; Andersen, Henning R

    2012-01-01

    AIMS: Previous studies indicate that ventricular pacing may precipitate heart failure (HF). We investigated occurrence of HF during long-term follow-up among patients with sick sinus syndrome (SSS) randomized to AAIR or DDDR pacing. Furthermore, we investigated effects of percentage of ventricular...

  20. 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.

  1. Gamma ray bursts of black hole universe

    Science.gov (United States)

    Zhang, T. X.

    2015-07-01

    Slightly modifying the standard big bang theory, Zhang recently developed a new cosmological model called black hole universe, which has only a single postulate but is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain existing observations of the universe. In the previous studies, we have explained the origin, structure, evolution, expansion, cosmic microwave background radiation, quasar, and acceleration of black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This study investigates gamma ray bursts of black hole universe and provides an alternative explanation for the energy and spectrum measurements of gamma ray bursts according to the black hole universe model. The results indicate that gamma ray bursts can be understood as emissions of dynamic star-like black holes. A black hole, when it accretes its star or merges with another black hole, becomes dynamic. A dynamic black hole has a broken event horizon and thus cannot hold the inside hot (or high-frequency) blackbody radiation, which flows or leaks out and produces a GRB. A star when it collapses into its core black hole produces a long GRB and releases the gravitational potential energy of the star as gamma rays. A black hole that merges with another black hole produces a short GRB and releases a part of their blackbody radiation as gamma rays. The amount of energy obtained from the emissions of dynamic star-like black holes are consistent with the measurements of energy from GRBs. The GRB energy spectra derived from this new emission mechanism are also consistent with the measurements.

  2. Spectral Lag Evolution among -Ray Burst Pulses

    Indian Academy of Sciences (India)

    Lan-Wei Jia; Yun-Feng Liang; En-Wei Liang

    2014-09-01

    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 emission episode, possibly due to the longer lasting emission in a lower energy band, and the spectral lag may not be an intrinsic parameter to discriminate the long and short GRBs.

  3. Gamma Ray Bursts in the HAWC Era

    CERN Document Server

    Mészáros, Peter; Murase, Kohta; Fox, Derek; Gao, He; Senno, Nicholas

    2015-01-01

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  4. Classification of Fermi Gamma-RAY Bursts

    CERN Document Server

    Horvath, I; Hakkila, J; Bagoly, Z; Preece, R D

    2015-01-01

    The Fermi GBM Catalog has been recently published. Previous classification analyses of the BATSE, RHESSI, BeppoSAX, and Swift databases found three types of gamma-ray bursts. Now we analyzed the GBM catalog to classify the GRBs. PCA and Multiclustering analysis revealed three groups. Validation of these groups, in terms of the observed variables, shows that one of the groups coincides with the short GRBs. The other two groups split the long class into a bright and dim part, as defined by the peak flux. Additional analysis is needed to determine whether this splitting is only a mathematical byproduct of the analysis or has some real physical meaning.

  5. The Birthplaces of Gamma-Ray Bursts

    CERN Document Server

    Young, P A; Young, Patrick A.

    2007-01-01

    We use population synthesis to construct distributions of gamma-ray bursts (GRBs) for different proposed progenitor models. We use a description of star formation that takes into account the evolution of metallicity with redshift and galaxy mass, the evolution of galaxy mass with redshift, and the star formation rate with galaxy mass and redshift. We compare predicted distributions with redshift and metallicity to observations of GRB host galaxies and find that the the simple models cannot produce the observed distributions, but that current theoretical models can reproduce the observations within some constraints on the fraction of fallback black holes that produce GRBs.

  6. Are Gamma-ray Bursts Universal?

    OpenAIRE

    Eichler, David; Levinson, Amir

    2006-01-01

    It is noted that the Liang-Zhang correlation can be accounted for with the viewing angle interpretation proposed earlier. The Ghirlanda correlation, recently generalized by Nava et al (2006) to a wind profile, can be accounted for by the viewing angle interpretation accordingly generalized to a wind profile. Most of the scatter in the spectra and time-integrated brightness in $\\gamma$-ray bursts (GRB) can thus be accounted for by variation in two parameters, 1) the viewing angle and 2) the je...

  7. Thermomechanical analysis of fast-burst reactors

    International Nuclear Information System (INIS)

    Fast-burst reactors are designed to provide intense, short-duration pulses of neutrons. The fission reaction also produces extreme time-dependent heating of the nuclear fuel. An existing transient-dynamic finite element code was modified specifically to compute the time-dependent stresses and displacements due to thermal shock loads of reactors. Thermomechanical analysis was then applied to determine structural feasibility of various concepts for an EDNA-type reactor and to optimize the mechanical design of the new SPR III-M reactor

  8. Decay time of type III solar bursts

    International Nuclear Information System (INIS)

    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 = 3r0.7. (U.S.)

  9. Burst-Mode Asynchronous Controllers on FPGA

    Directory of Open Access Journals (Sweden)

    Duarte L. Oliveira

    2008-01-01

    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.

  10. Prompt Emission Observations of Swift BAT Bursts

    Science.gov (United States)

    Barthelmy, Scott

    2009-01-01

    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. Thermal radiation from a nuclear weapon burst

    International Nuclear Information System (INIS)

    The different methods and correlations used to calculate the propagation of thermal radiation are reviewed and compared. A simple method to account for radiation enhancement by reflection from a superior cloud deck or snow cover, as well as attenuation of radiation by cloud cover below the burst is presented. The results show that the thermal reach may vary considerably. Additional calculation show that a significant fraction of the thermal energy may be incident after the arrival of the shock wave. Results for a range of weapon yields are presented, and the implications for blast-induced (secondary) fire starts are discussed

  12. Plasma bursts in deep penetration laser welding

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Šarbort, Martin

    Amsterdam: Elsevier, 2014, s. 1-1436. ISSN 1875-3892. [LANE 2014. International Conference on Photonic Technolgies /8./. Fürth (DE), 08.09.2014-11.09.2014] R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212; GA MŠk EE2.4.31.0016; GA MPO 2A-3TP1/113 Institutional support: RVO:68081731 Keywords : laser welding * plasma bursts * intensity oscillations * frequency analysis Subject RIV: BH - Optics, Masers, Lasers

  13. The repeating Fast Radio Burst FRB 121102: Multi-wavelength observations and additional bursts

    CERN Document Server

    Scholz, P; Hessels, J W T; Chatterjee, S; Cordes, J M; Kaspi, V M; Wharton, R S; Bassa, C G; Bogdanov, S; Camilo, F; Crawford, F; Deneva, J; van Leeuwen, J; Lynch, R; Madsen, E C; McLaughlin, M A; Mickaliger, M; Parent, E; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; Tendulkar, S P

    2016-01-01

    We report on radio and X-ray observations of the only known repeating Fast Radio Burst (FRB) source, FRB 121102. We have detected six additional radio bursts from this source: five with the Green Bank Telescope at 2 GHz, and one at 1.4 GHz at the Arecibo Observatory for a total of 17 bursts from this source. All have dispersion measures consistent with a single value ($\\sim559$ pc cm$^{-3}$) that is three times the predicted maximum Galactic value. The 2-GHz bursts have highly variable spectra like those at 1.4 GHz, indicating that the frequency structure seen across the individual 1.4 and 2-GHz bandpasses is part of a wideband process. X-ray observations of the FRB 121102 field with the Swift and Chandra observatories show at least one possible counterpart; however, the probability of chance superposition is high. A radio imaging observation of the field with the Jansky Very Large Array at 1.6 GHz yields a 5$\\sigma$ upper limit of 0.3 mJy on any point-source continuum emission. This upper limit, combined wit...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    year) and other transient sources, and to deliver their localization in less than 30 seconds to the observers, via a VHF antenna network. Real-time full resolution data download to ground being impossible, the real-time data processing is performed onboard by the LBOT (LOFT Burst On-board Trigger...

  15. The Second SWIFT Burst Alert Telescope (BAT) Gamma-Ray Burst Catalog

    Science.gov (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.; Sato, G.; Stamatikos, M.; Tueller, J.; Ukwatta, T. N.; Zhang, B.

    2012-01-01

    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.

  16. Ectopic jejunal pacemakers and gastric emptying after Roux gastrectomy: Effect of intestinal pacing

    International Nuclear Information System (INIS)

    The aims of this study were to determine whether ectopic pacemakers are present after meals in the Roux limbs of dogs after vagotomy and Roux gastrectomy, whether these pacemakers slow gastric emptying of liquids or solids, and whether abolishing the pacemakers with electric pacing might speed any slow emptying that occurs. In six dogs that underwent vagotomy and Roux gastrectomy and in four dogs that underwent vagotomy and Billroth gastrectomy (controls), myoelectric activity of the Roux limb or duodenum was measured during gastric emptying of a 500 kcal mixed meal of 99mTc-labeled cooked egg and 111In-labeled milk. Roux dogs were tested with and without pacing of the Roux limb. Roux dogs showed ectopic pacemaker in the Roux limb that drove the pacesetter potentials of the limb in a reverse, or orad, direction during 57% of the postprandial recordings. Billroth dogs had no ectopic pacemakers (p less than 0.05). Liquids emptied more slowly in Roux dogs (half-life (t1/2) = 121 +/- 15 minutes) than in Billroth dogs (t1/2 = 43 +/- 9 minutes; p less than 0.05), but solids emptied similarly in both groups of dogs (t1/2 approximately 8 hours). Pacing the Roux limb abolished the ectopic pacemakers, restored the slow emptying of liquids to the more rapid rate found in the Billroth dogs (t1/2: paced Roux, 72 +/- 15 minutes; Billroth, 43 +/- 9 minutes; p greater than 0.05) and did not change emptying of solids. The conclusion was that ectopic pacemakers present in the Roux limb after vagotomy and Roux gastrectomy drove the limb in a reverse direction and slowed emptying of liquids after the operation. The defect was corrected by pacing the Roux limb in a forward direction

  17. Remote Sensing Ocean Color Observations from NASA's PACE Mission: Applications and Societal Benefits

    Science.gov (United States)

    Tzortziou, M.; Omar, A. H.; Turner, W.

    2014-12-01

    The PACE (Pre- Aerosol, Clouds and ocean Ecosystems) 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 and ecology, and determining how the ocean's role in global biogeochemical cycling and ocean ecology both affects and is affected by climate change. With advanced global remote sensing capabilities that include high spectral-resolution imaging, extended spectral coverage to the UV and SWIR, improved spatial resolution in inland, estuarine and coastal waters, enhanced atmospheric correction and higher signal-to-noise, PACE is expected to provide high quality observations that, over the long-term, will contribute to an extended time series of records on inland, coastal, and ocean ecosystems—all of which have substantial value beyond basic science and research. The combination of climate-quality, global atmospheric and oceanic observations provided by the PACE mission will provide a unique capability to help understand changes that affect our ecosystem services, implement science-based management strategies of coastal, marine and inland aquatic resources, and support assessments, policy analyses, and design approaches to plan adaptation and responses to impacts of climate change. Here we discuss the PACE applications program, the new capabilities afforded by this future satellite mission, and how they could potentially advance applications across a range of areas, including Oceans, Climate, Water Resources, Ecological Forecasting, Disasters, Human Health and Air Quality.

  18. Effect of Peripheral Communication Pace on Attention Allocation in a Dual-Task Situation

    Science.gov (United States)

    Gueddana, Sofiane; Roussel, Nicolas

    Peripheral displays allow continuous awareness of information while performing other activities. Monitoring such a display while performing a central task has a cognitive cost that depends on its perceptual salience and the distraction it causes, i.e. the amount of attention it attracts away from the user’s primary action. This paper considers the particular case of peripheral displays for interpersonal communication. It reports on an experiment that studied the effect of peripheral communication pace on subjects’ allocation of attention in a dual-task situation: a snapshot-based peripheral monitoring task where participants need to assess the presence of a remote person, and a central text-correcting task against the clock. Our results show that the addition of the peripheral task caused a drop in the success rate of the central task. As the pace of snapshots increased, success rate decreased on the peripheral task while on the central one, success rate remained the same but failures to reply in time occurred more frequently. These results suggest that the increase in pace of snapshots caused participants to change their strategy for the central task and allocate more attention to the peripheral one, not enough to maintain peripheral performance but also not to the point where it would affect central performance. Overall, our work suggests that peripheral communication pace subtly influences attention allocation in dual-task situations. We conclude by discussing how control over information pace could help users of communication systems to adjust their local distraction as well as the attention they draw from remote users.

  19. A Case Exemplar for National Policy Leadership: Expanding Program of All-Inclusive Care for the Elderly (PACE).

    Science.gov (United States)

    Cortes, Tara A; Sullivan-Marx, Eileen M

    2016-03-01

    In November 2015, President Obama signed the Program of All-Inclusive Care for the Elderly (PACE) Innovation Act, which expands a proven model of care to serve high-cost and high-need populations. Specifically, the law provides the Centers for Medicare & Medicaid Services with the authority to waive Medicaid requirements that could not be waived without additional statutory authority. Those requirements include the age of the beneficiary to be served and nursing home eligibility as a condition for PACE enrollment. The law also allows providers and other entities who are not current PACE providers the opportunity to become PACE providers and serve a predominately dually eligible population that has high needs and high cost through a coordinated, integrated model. The current article describes the impact of nursing on the legislation and policy that has shaped the evolution of the PACE program for more than 40 years. [Journal of Gerontological Nursing, 42(3), 9-14.]. PMID:26934968

  20. Some Comments On Fast Radio Burst

    CERN Document Server

    Luan, Jing

    2014-01-01

    Fast Radio Bursts (FRBs) are single $\\mathrm{ms}$ radio pulses with dispersion measures (DM) ranging up to $\\sim 10^3\\mathrm{pc cm^{-3}}$. It has been proposed that they originate from galactic flare stars, and that their DMs come from propagation through the stellar corona. We disapprove this hypothesis by showing that free-free absorption would conceal any radio signal emitted from below the corona. It appears that FRBs come from extragalactic sources. FRB 110220 has a scattering tail of several $\\mathrm{ms}$ Propagation through the intergalactic plasma is unlikely to account for scattering of this magnitude unless the intergalactic magnetic field is as large as $2.4\\times 10^{-9}\\mathrm{G}$. This suggests that this burst originated in the central region of an external galaxy. Extrapolated to cosmological distances and sources sizes of order $c\\Delta t$, the electric fields of FRBs are strong in the sense that they would accelerate thermal electrons to relativistic energies in less than a nanosecond.

  1. $\\gamma$-Ray Bursts and Related Phenomena

    CERN Document Server

    Piran, T

    1999-01-01

    Gamma-ray bursts (GRBs) have puzzled astronomers since their accidental discovery in the sixties. The BATSE detector on the COMPTON-GRO satellite has been detecting one burst per day for the last six years. Its findings have revolutionized our ideas about the nature of these objects. They have shown that GRBs are at cosmological distances. This idea was accepted with difficulties at first. However, the recent discovery of an x-ray afterglow by the Italian/Dutch satellite BeppoSAX led to a detection of high red-shift absorption lines in the optical afterglow of GRB970508 and to a confirmation of its cosmological origin. The simplest and practically inevitable interpretation of these observations is that GRBs result from the conversion of the kinetic energy of ultra-relativistic particles flux to radiation in an optically thin region. The "inner engine" that accelerates the particles or generates the Poynting flux is hidden from direct observations. Recent studies suggest the ``internal-external'' model: intern...

  2. Gamma Ray Bursts Cook Book I: Formulation

    CERN Document Server

    Ziaeepour, Houri

    2008-01-01

    Since the suggestion of relativistic shocks as the origin of gamma-ray bursts (GRBs) in early 90's, the mathematical formulation of this process has stayed at phenomenological level. One of the reasons for the slow development of theoretical works in this domain has been the simple power-law behaviour of the afterglows hours or days after the prompt gamma-ray emission. Nowadays with the launch of the Swift satellite, gamma-ray bursts can be observed in multi-wavelength from a few tens of seconds after trigger onward. These observations have leaded to the discovery of features unexplainable by the simple formulation of the shocks and emission processes used up to now. But "devil is in details" and some of these features may be explained with a more detailed formulation of phenomena and without adhoc addition of new processes. Such a formulation is the goal of this work. We present a consistent formulation of the collision between two spherical relativistic shells. The model can be applied to both internal and ...

  3. Gamma Ray Bursts Cook Book II: Simulation

    CERN Document Server

    Ziaeepour, Houri

    2008-01-01

    In Paper I we presented a detailed formulation of the relativistic shocks and synchrotron emission in the context of Gamma-Ray Burst (GRB) physics. To see how well this model reproduces the observed characteristics of the GRBs and their afterglows, here we present the results of some simulations based on this model. They are meant to reproduce the prompt and afterglow emission in some intervals of time during a burst. We show that this goal is achieved for both short and long GRBs and their afterglows, at least for part of the parameter space. Moreover, these results are the evidence of the physical relevance of the two phenomenological models we have suggested in Paper I for the evolution of the "active region", the synchrotron emitting region in a shock. The dynamical active region model seems to reproduce the observed characteristics of prompt emissions better than the quasi-steady model which is more suitable for afterglows. Therefore these simulations confirm the arguments presented in Paper I about the ...

  4. The interplanetary gamma ray burst network

    Science.gov (United States)

    Cline, T.

    The Interplanetary Gamma-Ray Burst Network (IPN) is providing gamma-ray burst (GRB) alerts and localizations at the maximum rate anticipated before the launch of the Swift mission. The arc-minute source precision of the IPN is again permitting searches for GRB afterglows in the radio and optical regimes with delays of only hours up to 2 days. The successful addition of the Mars Odyssey mission has compensated for the loss of the asteroid mission NEAR, to reconstitute a fully long- baseline interplanetary network, with Ulysses at > 5 AU and Konus-Wind and HETE-2 near the Earth. In addition to making unassisted GRB localizations that enable a renewed supply of counterpart observations, the Mars/Ulysses/Wind IPN is confirming and reinforcing GRB source localizations with HETE-2. It has also confirmed and reinforced localizations with the BeppoSAX mission before the BeppoSAX termination in May and has detected and localized both SGRs and an unusual hard x-ray transient that is neither an SGR nor a GRB. This IPN is expected to operate until at least 2004.

  5. Fast Radio Bursts from Axion Stars

    CERN Document Server

    Iwazaki, Aiichi

    2014-01-01

    Axions are one of the most promising candidates of dark matter. The axions have been shown to form miniclusters with masses $\\sim 10^{-12}M_{\\odot}$ and to become dominant component of dark matter. These axion miniclusters condense to form axion stars. We show a possible origin of fast radio bursts ( FRBs ) by assuming the axion stars being dark matter: FRBs arise from the collisions between the axion stars and neutron stars. The FRBs are caused by the rapid conversion of the axions into electromagnetic fields under strong magnetic fields. Electric fields are induced on the axion stars under strong magnetic fields of neutron stars. The electric fields parallel to the magnetic fields oscillate with a frequency and make electrons in atmospheres of neutron stars coherently oscillate. Thus, the coherent radiations are emitted. The observed frequencies ( $\\sim 1.4$GHz ) of the bursts are given by the axion mass $m_a$ such as $m_a/2\\pi\\simeq 2.3\\,\\mbox{GHz}\\,\\big(m_a/10^{-5}\\mbox{eV}\\big)$. The frequency is affecte...

  6. Photospheric Emission in Gamma-Ray Bursts

    CERN Document Server

    Pe'er, Asaf

    2016-01-01

    A major breakthrough in our understanding of gamma-ray bursts (GRB) prompt emission physics occurred in the last few years, with the realization that a thermal component accompanies the over-all non-thermal prompt spectra. This thermal part is important by itself, as it provides direct probe of the physics in the innermost outflow regions. It further has an indirect importance, as a source of seed photons for inverse-Compton scattering, thereby it contributes to the non-thermal part as well. In this short review, we highlight some key recent developments. Observationally, although so far it was clearly identified only in a minority of bursts, there are indirect evidence that thermal component exists in a very large fraction of GRBs, possibly close to 100%. Theoretically, the existence of thermal component have a large number of implications as a probe of underlying GRB physics. Some surprising implications include its use as a probe of the jet dynamics, geometry and magnetization.

  7. Distribution of Gamma-Ray Bursts

    Science.gov (United States)

    Diaz Rodriguez, Mariangelly; Smith, M.; Tešic, G.

    2014-01-01

    Gamma-Ray Bursts (GRBs) are known to be bright, irregular flashes of gamma rays that typically last just a few seconds, believed to be caused by stellar collapse or the merger of a pair of compact objects. Through previous work, it has been found that GRBs are distributed roughly uniformly over the entire sky, rather than being confined to the relatively narrow band of the Milky Way. Using the Python programming language, we generated a model of GRBs over cosmological distances, based on current empirical GRB distributions. The grbsim python module uses the acceptance-rejection Monte Carlo method to simulate the luminosity and redshift of a large population of GRBs, including cosmological effects such as dark energy and dark matter terms that modify the large-scale structure of space-time. The results of running grbsim are demonstrated to match the distribution of GRBs observed by the Burst Alert Telescope on NASA’s Swift satellite. The grbsim module will subsequently be used to simulate gamma ray and neutrino events for the Astrophysical Multimessenger Observatory Network.

  8. Star bursts and giant HII regions

    International Nuclear Information System (INIS)

    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.)

  9. The Most Remote Gamma-Ray Burst

    Science.gov (United States)

    2000-10-01

    ESO Telescopes Observe "Lightning" in the Young Universe Summary Observations with telescopes at the ESO La Silla and Paranal observatories (Chile) have enabled an international team of astronomers [1] to measure the distance of a "gamma-ray burst", an extremely violent, cosmic explosion of still unknown physical origin. It turns out to be the most remote gamma-ray burst ever observed . The exceedingly powerful flash of light from this event was emitted when the Universe was very young, less than about 1,500 million years old, or only 10% of its present age. Travelling with the speed of light (300,000 km/sec) during 11,000 million years or more, the signal finally reached the Earth on January 31, 2000. The brightness of the exploding object was enormous, at least 1,000,000,000,000 times that of our Sun, or thousands of times that of the explosion of a single, heavy star (a "supernova"). The ESO Very Large Telescope (VLT) was also involved in trail-blazing observations of another gamma-ray burst in May 1999, cf. ESO PR 08/99. PR Photo 28a/00 : Sky field near GRB 000131 . PR Photo 28b/00 : The fading optical counterpart of GRB 000131 . PR Photo 28c/00 : VLT spectrum of GRB 000131 . What are Gamma-Ray Bursts? One of the currently most active fields of astrophysics is the study of the mysterious events known as "gamma-ray bursts" . They were first detected in the late 1960's by instruments on orbiting satellites. These short flashes of energetic gamma-rays last from less than a second to several minutes. Despite much effort, it is only within the last few years that it has become possible to locate the sites of some of these events (e.g. with the Beppo-Sax satellite ). Since the beginning of 1997, astronomers have identified about twenty optical sources in the sky that are associated with gamma-ray bursts. They have been found to be situated at extremely large (i.e., "cosmological") distances. This implies that the energy release during a gamma-ray burst within a few

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    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...

  11. 34 First Callisto solar burst spectrometer station in Greenland

    Science.gov (United States)

    Monstein, Christian

    2016-04-01

    In mid of March 2016 a new long wavelength station in Greenland was set into operation. It is a dual circular polarization, frequency agile solar radio burst spectrometer based on two Callisto spectrometers and the Long Wavelength Array antenna. During the commissioning phase several nice radio burst observations proved that the system works as expected.

  12. The WATCH solar X-ray burst catalogue

    DEFF Research Database (Denmark)

    Crosby, N.; Lund, Niels; Vilmer, N.; Sunyaev, R.

    1998-01-01

    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...... for each burst is given and are furthermore explained....

  13. Large tundra methane burst during onset of freezing

    DEFF Research Database (Denmark)

    Mastepanov, Mikhail; Sigsgaard, Charlotte; Dlugokencky, Edward J.; Houweling, Sander; Ström, Lena; Tamstorf, Mikkel Peter; Christensen, Torben R.

    2008-01-01

    model simulations 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...

  14. On the existence of optimum cyclic burst-correcting codes

    OpenAIRE

    1986-01-01

    It is shown that for each integer b >= 1 infinitely many optimum cyclic b-burst-correcting codes exist, i.e., codes whose length n, redundancy r, and burst-correcting capability b, satisfy n = 2^{r-b+1} - 1. Some optimum codes for b = 3, 4, and 5 are also studied in detail.

  15. 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 of...

  16. The INTEGRAL view of intermediate long X-ray bursts

    DEFF Research Database (Denmark)

    CONCLUSIONS Most intermediate bursts are observed from low luminosity sources and are interpreted as long pure He bursts. If no H is accreted, they are consistent with the burning of a slowly accreted, thick He layer, in Ultra Compact X-ray Binaries (UCXB) where the donor star is probably a...

  17. Spike-type broad-band solar bursts

    International Nuclear Information System (INIS)

    High-resolution dynamical spectra of solar broad-band spike bursts (BSB) have been observed. They represent an instantaneous brightening of the continuum emission in the range 175-235 MHz. In the noise stoms the BSB-type events occur seldom and have the form of either individual bursts with the average lifetime of 0.1-0.2 s or the groups of such bursts, related with type 3 bursts at lower frequencies. In type 4 bursts, the series of nonperiodic structures of BSB predominate. They are not related with type 3 bursts, but are observed together with the second pulsations and fiber bursts. In the noise storms, the BSB can be excited by electrons instantaneously accelerated owing to the magnetic field reconnection. The group delay leads to a negative frequency drift approximately -600 MHz/s in small sources and positive drift approximately 300 MHz/s in the extended ones. Such a high drift velocity cannot compensate the moderate frequency drift associated with the exciter motion in the corona. The BSB-structure in type 4 bursts can be the result of scattering of the Langmuir waves on the whistlers in a large height interval

  18. Supernova sheds light on gamma-ray bursts

    CERN Multimedia

    2003-01-01

    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)

  19. Testing and Performance of UFFO Burst Alert & Trigger Telescope

    DEFF Research Database (Denmark)

    Rípa, Jakub; Bin Kim, Min; Lee, Jik;

    2014-01-01

    The Ultra-Fast Flash Observatory pathfinder (UFFO-p) is a new space mission dedicated to detect Gamma-Ray Bursts (GRBs) and rapidly follow their afterglows in order to provide early optical/ultraviolet measurements. A GRB location is determined in a few seconds by the UFFO Burst Alert & Trigger...

  20. Solar U- and J- radio bursts at the decameter waves

    Science.gov (United States)

    Dorovskyy, V. V.; Melnik, V. N.; Konovalenko, A. A.; Rucker, H. O.; Abranin, E. P.; Lecacheux, A.

    2010-01-01

    The results of the first observations of solar U- and J- bursts with the radiotelescope UTR-2 at the decameter wavelengths are reported. During 2003-2004 more than 50 J- bursts and only 7 U- bursts were registered. It is the first case of ground based observations of J- and U- bursts with turning frequencies below 25 MHz. For the first time the harmonic structure of J- bursts in the form of Jb-J pairs was found. The mean harmonic ratio appeared to be 1.8. Also a group of J-bursts with unusual Turning Frequency Drift (TFD) of -2 kHz/s was detected. Such TFD corresponds to the velocity of coronal loop elevation of about 60 km/s. Coronal loops with similar elevation velocities were also detected by SOHO-LASCO coronagraph in white light. The dynamic spectra of unusual U- and J- bursts are shown. Simplified model of the coronal loop in the form of semicircle was created on the base of the U- burst dynamic spectrum and the Newkirk coronal density model. With this loop model the linear velocity of the source along the loop, the height of the Turning Frequency point and the geometrical size of the loop were calculated.

  1. Ionospheric response to gamma ray bursts of cosmic origin

    International Nuclear Information System (INIS)

    The paper examines the limiting conditions under which is detectable, through the VLF phase-meter, a gamma-ray burst of cosmic origin like those recently observed by Vela spacecrafts. The discussion focuses on the flux density and burst duration and leads to a definition of the threshold needed for a measurable effect

  2. Periodic bursts of Jovian non-Io decametric radio emission.

    Science.gov (United States)

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

    2013-03-01

    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 [Formula: see text] 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° and 60° (via 360°). 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 [Formula: see text] 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. PMID:23585696

  3. Taming desynchronized bursting with delays in the Macaque cortical network

    Institute of Scientific and Technical Information of China (English)

    Wang Qing-Yun; Murks Aleksandra; Perc Matja(z); Lu Qi-Shao

    2011-01-01

    Inhibitory coupled bursting Hindmarsh-Rose neurons are considered as constitutive units of the Macaque cortical network. In the absence of information transmission delay the bursting activity is desynchronized, giving rise to spatiotemporally disordered dynamics. This paper shows that the introduction of finite delays can lead to the synchroization of bursting and thus to the emergence of coherent propagating fronts of excitation in the space-time domain.Moreover, it shows that the type of synchronous bursting is uniquely determined by the delay length, with the transitions from one type to the other occurring in a step-like manner depending on the delay. Interestingly, as the delay is tuned close to the transition points, the synchronization deteriorates, which implies the coexistence of different bursting attractors. These phenomena can be observed be different but fixed coupling strengths, thus indicating a new role for information transmission delays in realistic neuronal networks.

  4. Models for Gamma-Ray Burst Progenitors and Central Engines

    CERN Document Server

    Woosley, S E

    2011-01-01

    Most gamma-ray bursts are made during the deaths of massive stars. Here the environmental circumstances, stellar evolutionary paths, and explosion physics that might produce the bursts are reviewed. Neither of the two leading models - collapsar and millisecond magnetar - can be excluded, and both may operate in progenitor stars of different masses, metallicities, and rotation rates. Potential diagnostics are discussed and uncertainties highlighted. Both models are capable of producing a wide variety of transients whose properties vary with both stellar properties and viewing angle. Some of these are reviewed including the possibility of very long (days) low luminosity bursts, so far undiscovered, short hard bursts from massive stellar progenitors, and bursts from very massive Population III stars.

  5. The supernova-gamma-ray burst-jet connection.

    Science.gov (United States)

    Hjorth, Jens

    2013-06-13

    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. PMID:23630379

  6. Cosmology and the Subgroups of Gamma-ray Bursts

    Directory of Open Access Journals (Sweden)

    A. Mészáros

    2011-01-01

    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.

  7. First Results from the Swift Gamma Ray Burst Mission

    Science.gov (United States)

    Gehreis, Neil

    2005-01-01

    Swift is now in orbit after a beautiful launch on November 20, 2004. It is a multiwavelength observatory designed specifically to study the fascinating gamma-ray bursts. The goals are to determine the origin of bursts and use them to probe the early Universe. A new-technology wide-field gamma-ray camera detects more than a hundred bursts per year. Sensitive narrow-field X-ray and UV/optical telescopes are pointed at the burst location in 20 to 70 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. First results from the mission will be presented, including observations of bright GRBs, faint GRBs, short GRBs and a super-giant flare from the soft gamma repeater SGRl806-20.

  8. Do Gamma-Ray Bursts Come from the Oort Cloud?

    CERN Document Server

    Clarke, T E; Tremaine, S; Tremaine, adn S.

    1993-01-01

    We examine the possibility that gamma-ray bursts arise from sources in the Oort comet cloud, basing most of our arguments on accepted models for the formation and spatial distribution of the cloud. We identify three severe problems with such models: (1) There is no known mechanism for producing bursts that can explain the observed burst rate and energetics without violating other observational constraints. (2) The bright source counts cannot be reconciled with standard models for the phase-space distribution of objects in the Oort cloud. (3) The observed isotropy of the available burst data is inconsistent with the expected angular distribution of sources in the Oort cloud. We therefore assert that Oort cloud models of gamma-ray bursts are extremely implausible.

  9. Amplitude sorting of oscillatory burst signals by sampling

    Science.gov (United States)

    Davis, Thomas J.

    1977-01-01

    A method and apparatus for amplitude sorting of oscillatory burst signals is described in which the burst signal is detected to produce a burst envelope signal and an intermediate or midportion of such envelope signal is sampled to provide a sample pulse output. The height of the sample pulse is proportional to the amplitude of the envelope signal and to the maximum burst signal amplitude. The sample pulses are fed to a pulse height analyzer for sorting. The present invention is used in an acoustic emission testing system to convert the amplitude of the acoustic emission burst signals into sample pulse heights which are measured by a pulse height analyzer for sorting the pulses in groups according to their height in order to identify the material anomalies in the test material which emit the acoustic signals.

  10. Evaluating the risk of coal bursts in underground coal mines

    Institute of Scientific and Technical Information of China (English)

    Mark Christopher⇑; Gauna Michael

    2016-01-01

    Coal bursts involve the sudden, violent ejection of coal or rock into the mine workings. They are almost always accompanied by a loud noise, like an explosion, and ground vibration. Bursts are a particular haz-ard for miners because they typically occur without warning. Despite decades of research, the sources and mechanics of these events are not well understood, and therefore they are difficult to predict and control. Experience has shown, however, that certain geologic and mining factors are associated with an increased likelihood of a coal burst. A coal burst risk assessment consists of evaluating the degree to which these risk factors are present, and then identifying appropriate control measures to mitigate the hazard. This paper summarizes the U.S. and international experience with coal bursts, and describes the known risk factors in detail. It includes a framework that can be used to guide the risk assessment process.

  11. IDENTIFICATION OF BURSTING WATER MASER FEATURES IN ORION KL

    International Nuclear Information System (INIS)

    In 2011 February, a burst event of the H2O 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 H2O 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 104 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 H2O maser burst.

  12. Automatic recognition of type III solar radio bursts. Automated radio burst identification system method and first observations

    International Nuclear Information System (INIS)

    Complete text of publication follows. Because of the rapidly increasing role of technology, including complicated electronic systems, spacecraft, etc., modern society has become more vulnerable to a set of extraterrestrial influences (space weather) and requires continuous observation and forecasts of space weather. The major space weather events like solar flares and coronal mass ejections are usually accompanied by solar radio bursts, which can be used for a real-time space weather forecast. Coronal type III radio bursts are produced near the local electron plasma frequency and near its harmonic by fast electrons ejected from the solar active regions and moving through the corona and solar wind. These bursts have dynamic spectra with frequency rapidly falling with time, the typical duration of the coronal burst being about 1-3 s. This paper presents a new method developed to detect coronal type III bursts automatically and its implementation in a new Automated Radio Burst Identification System (ARBIS), which is working in real-time. The central idea of the implementation is to use the Radon transform for more objective detection of the bursts as approximately straight lines in dynamic spectra. Preliminary tests of the method with the use of the spectra obtained during 13 days show that the performance of the current implementation is quite high, ∼84%, while no false positives are observed and 23 events not listed previously are found. The first automatically detected coronal type III radio bursts are presented.

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

    KAUST Repository

    Ali, Mohammed L.

    2011-10-10

    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.

  14. Brief time-based activity pacing instruction as a singular behavioral intervention was not effective in participants with symptomatic osteoarthritis.

    Science.gov (United States)

    Murphy, Susan L; Kratz, Anna L; Kidwell, Kelley; Lyden, Angela K; Geisser, Michael E; Williams, David A

    2016-07-01

    Osteoarthritis (OA) of the lower extremities is a prevalent cause of disability in which symptoms interfere with mobility and activity participation. Behavioral self-management for OA symptomatology is commonly recommended; but these interventions are underutilized, unstandardized in application, and at times, unavailable in the context of clinical care. For people with chronic pain, rehabilitation professionals may select to apply activity pacing instruction as one behavioral strategy to manage symptoms. Activity pacing is widely used in combination with other pharmacological and behavioral interventions but has not been studied as a singular behavioral intervention for people with OA. The purpose of this study was to evaluate the effectiveness of an occupational therapist-delivered, time-based activity pacing program for treatment of pain, fatigue, and physical function in people with symptomatic knee or hip OA. A 3-arm randomized controlled trial was conducted in which 193 people were randomized into tailored activity pacing, general activity pacing, or usual care arms. Assessments were done at 10 weeks and 6 months after baseline. Using linear mixed models, Western Ontario and McMaster Universities Osteoarthritis Index pain scores changed over time, decreasing the most in the general and usual care groups; only the usual care group had decreased pain over 6 months. The tailored and general activity pacing groups reported higher frequency of pacing behaviors than the usual care group at 10 weeks, but pacing was not sustained at 6 months. This trial does not support the use of time-based pacing as a singular behavioral strategy for people with knee or hip OA. PMID:26963847

  15. Pace yourself: Improving time-saving judgments when increasing activity speed

    Directory of Open Access Journals (Sweden)

    Eyal Peer

    2013-03-01

    Full Text Available The time-saving bias describes people's tendency to misestimate the time they can save by increasing the speed in which they perform an activity such as driving or completing a task. People typically underestimate time saved when increasing from a low speed and overestimate time saved when increasing from an already high speed. We suggest that this bias is the result of people's failure to recognize the curvilinear relationship between increasing speed and reducing activity time: As initial speed rises, the same speed increases will yield smaller reductions in time. We explore a new technique to de-bias these faulty estimations: converting measurements of speed to a pace measure (e.g., minutes per fixed distance. Utilizing common driving scenarios, we show that participants who received pace data made more accurate estimations of journey duration at various speeds, time-savings at various speed increases and the required speed to complete a journey.

  16. Leave-one-out prediction error of systolic arterial pressure time series under paced breathing

    CERN Document Server

    Ancona, N; Marinazzo, D; Nitti, L; Pellicoro, M; Pinna, G D; Stramaglia, S

    2004-01-01

    In this paper we show that different physiological states and pathological conditions may be characterized in terms of predictability of time series signals from the underlying biological system. In particular we consider systolic arterial pressure time series from healthy subjects and Chronic Heart Failure patients, undergoing paced respiration. We model time series by the regularized least squares approach and quantify predictability by the leave-one-out error. We find that the entrainment mechanism connected to paced breath, that renders the arterial blood pressure signal more regular, thus more predictable, is less effective in patients, and this effect correlates with the seriousness of the heart failure. The leave-one-out error separates controls from patients and, when all orders of nonlinearity are taken into account, alive patients from patients for which cardiac death occurred.

  17. IN VIVO CHARACTERIZATION OF ATTACHMENT SAFETY BETWEEN CARDIAC PACING LEAD AND CANINE HEART MUSCLE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In vivo experiments of screwing the electrode of canine hearts and assigning external excitation on the lead-myocardium interface was carried out to evaluate the lead/myocardium adherence safety. The electrode is specially designed to host a measurement unit of strain gauges.We obtained the lead/heart interactions data from 12 dogs under natural heart beating and beating with external excitations. The data recorded from the acute phase and the chronic phase of pulling out pacing leads were compared with each other. The electrode/heart interaction is caused by the heart beat and influenced by the lung breath. This process induced tolerable damage to the lead or myocardium. The interaction decreases as the frequency of external excitations increases. The lead is more likely to be detached from myocardium under higher excitation frequency. At the same implanting sites, safer pacing lead/myocardium attachment can be realized in the chronic tests than in the acute tests.

  18. Dynamic exploration of myocardial perfusion by coronary blood flow radioisotopic measurement during auricular pacing

    International Nuclear Information System (INIS)

    Reproducibility of the radiocardiographic method using 42 Potassium has been verified. Coronary blood flow has so been measured in 50 control subjects and coronary heart disease patients, at steady state and during auricular pacing at 150 beats per minute. In control subjects group, under auricular pacing coronary blood flow increases by a mean value of 15%; on the other hand it decreases by a mean value of 32% in coronary heart disease patients bearing obvious coronarography lesions. The cardiac output coronary fraction increases by a mean value of 27% in the control subjects group; it remains unchanged in coronary heart disease patients. On the contrary this coronary fraction increases in a significant way after functional aortocoronary bypass

  19. Trame di Pace. Simboli, carte, azioni di un’utopia possibile. 1945-2003

    Directory of Open Access Journals (Sweden)

    Nadia Baiesi

    2014-06-01

    Full Text Available La mostra racconta la storia degli uomini e delle donne che hanno ragionato di pace non più come di una nobile speranza, ma come dell’unica chance di salvezza per l’umanità. La scansione cronologica, per decenni, parte dal 1945 e arriva al 2003 con la diffusione della bandiera arcobaleno in occasione della campagna «Pace da tutti i balconi», nata per scongiurare il secondo conflitto in Iraq. Al centro della mostra un percorso sui simboli che sono stati inventati, ripresi, risignificati in diversi contesti, movimenti radicali del pacifismo antimilitarista e nonviolento e movimenti contro singole guerre. Accompagnano i materiali iconografici (bandiere e manifesti originali, opere d’arte del maestro Anastasi, due percorsi documentari con immagini d’epoca, locandine, testi di decreti, opuscoli, volantini, articoli di quotidiani e riviste.

  20. Self-Paced E-Training in E-Learning for University Teaching Staff

    Directory of Open Access Journals (Sweden)

    Norah Ahmed Al-Malki

    2015-03-01

    Full Text Available The shift towards adopting e-training methods and practices in the workplace to equip staff with soft and hard skills have become an essential component of training in many Higher Education institutions. The aim of this paper is to advocate such a shift in Saudi universities through presenting the preliminary outcomes of a short-scale pilot study conducted by the Deanship of E-learning and Distance Education (DELDE during August 2014. Basically, the paper introduces the results of a first run of a self-paced e-training program focusing on introducing topics related to e-learning development and instruction. The paper 1 explores the pedagogical motivation for adopting the self-paced learning model, 2 outlines the elements of the developed course, and 3 discusses the results of the first run of the e-training program.

  1. Pacing, packing and sex-based differences in Olympic and IAAF World Championship marathons.

    Science.gov (United States)

    Hanley, Brian

    2016-09-01

    The aim of this study was to describe pacing profiles and packing behaviours of athletes in Olympic and World Championship marathons. Finishing and split times were collated for 673 men and 549 women across nine competitions. The mean speeds for each intermediate 5 km and end 2.2 km segments were calculated. Medallists of both sexes maintained even-paced running from 10 km onwards whereas slower finishers dropped off the lead pack at approximately half-distance. Athletes who ran with the same opponents throughout slowed the least in the second half (P sex-based differences in tactics adopted and design training programmes accordingly. PMID:26736042

  2. BET 2: Diagnosing acute myocardial infarction in the presence of ventricular pacing: can Sgarbossa criteria help?

    Science.gov (United States)

    Jothieswaran, Arunan; Body, Richard

    2016-09-01

    The Sgarbossa criteria can be used to identify patients who have acute myocardial infarction (AMI) in the presence of left bundle branch block, which obscures the usual changes associated with ST elevation myocardial infarction. Patients with ventricular paced rhythm have ECG changes with similar morphology to left bundle branch block. A short-cut systematic review was carried out to establish whether the Sgarbossa criteria can accurately diagnose AMI in the presence of ventricular paced rhythm. Three studies were directly relevant to the question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that. PMID:27539980

  3. Interaction Equivalency in Self-Paced Online Learning Environments: An Exploration of Learner Preferences

    Directory of Open Access Journals (Sweden)

    Jason F. Rhode

    2009-02-01

    Full Text Available This mixed methods study explored the dynamics of interaction within a self-paced online learning environment. It used rich media and a mix of traditional and emerging asynchronous computer-mediated communication tools to determine what forms of interaction learners in a self-paced online course value most and what impact they perceive interaction to have on their overall learning experience. This study demonstrated that depending on the specific circumstance, not all forms of interaction may be either equally valued by learners or effective. Participants differentiated among the various learning interactions available and indicated that informal interactions were as important as formal interactions in determining the quality of the online learning experience. Participants also reported the activity of blogging as being equally valued and in some ways superior to instructor-directed asynchronous discussion via the discussion board in a learning management system.

  4. Towards Development of a 3-State Self-Paced Brain-Computer Interface

    Directory of Open Access Journals (Sweden)

    Ali Bashashati

    2007-01-01

    the presence of a right- or a left-hand movement and the second classifies the detected movement as a right or a left one. In an offline analysis of the EEG data collected from four able-bodied individuals, the 3-state brain-computer interface shows a comparable performance with a 2-state system and significant performance improvement if used as a 2-state BCI, that is, in detecting the presence of a right- or a left-hand movement (regardless of the type of movement. It has an average true positive rate of 37.5% and 42.8% (at false positives rate of 1% in detecting right- and left-hand extensions, respectively, in the context of a 3-state self-paced BCI and average detection rate of 58.1% (at false positive rate of 1% in the context of a 2-state self-paced BCI.

  5. DiPALS: Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis - a randomised controlled trial.

    Science.gov (United States)

    McDermott, Christopher J; Bradburn, Mike J; Maguire, Chin; Cooper, Cindy L; Baird, Wendy O; Baxter, Susan K; Cohen, Judith; Cantrill, Hannah; Dixon, Simon; Ackroyd, Roger; Baudouin, Simon; Bentley, Andrew; Berrisford, Richard; Bianchi, Stephen; Bourke, Stephen C; Darlison, Roy; Ealing, John; Elliott, Mark; Fitzgerald, Patrick; Galloway, Simon; Hamdalla, Hisham; Hanemann, C Oliver; Hughes, Philip; Imam, Ibrahim; Karat, Dayalan; Leek, Roger; Maynard, Nick; Orrell, Richard W; Sarela, Abeezar; Stradling, John; Talbot, Kevin; Taylor, Lyn; Turner, Martin; Simonds, Anita K; Williams, Tim; Wedzicha, Wisia; Young, Carolyn; Shaw, Pamela J

    2016-01-01

    BACKGROUND Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease resulting in death, usually from respiratory failure, within 2-3 years of symptom onset. Non-invasive ventilation (NIV) is a treatment that when given to patients in respiratory failure leads to improved survival and quality of life. Diaphragm pacing (DP), using the NeuRx/4(®) diaphragm pacing system (DPS)™ (Synapse Biomedical, Oberlin, OH, USA), is a new technique that may offer additional or alternative benefits to patients with ALS who are in respiratory failure. OBJECTIVE The Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis (DiPALS) trial evaluated the effect of DP on survival over the study duration in patients with ALS with respiratory failure. DESIGN The DiPALS trial was a multicentre, parallel-group, open-label, randomised controlled trial incorporating health economic analyses and a qualitative longitudinal substudy. PARTICIPANTS Eligible participants had a diagnosis of ALS (ALS laboratory-supported probable, clinically probable or clinically definite according to the World Federation of Neurology revised El Escorial criteria), had been stabilised on riluzole for 30 days, were aged ≥ 18 years and were in respiratory failure. We planned to recruit 108 patients from seven UK-based specialist ALS or respiratory centres. Allocation was performed using 1 : 1 non-deterministic minimisation. INTERVENTIONS Participants were randomised to either standard care (NIV alone) or standard care (NIV) plus DP using the NeuRX/4 DPS. MAIN OUTCOME MEASURES The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Secondary outcomes were patient quality of life [assessed by European Quality of Life-5 Dimensions, three levels (EQ-5D-3L), Short Form questionnaire-36 items and Sleep Apnoea Quality of Life Index questionnaire]; carer quality of life (EQ-5D-3L and Caregiver Burden Inventory); cost-utility analysis and health

  6. A POSSIBLE CONNECTION BETWEEN FAST RADIO BURSTS AND GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    The physical nature of fast radio bursts (FRBs), a new type of cosmological transient discovered recently, is not known. It has been suggested that FRBs can be produced when a spinning supra-massive neutron star loses centrifugal support and collapses to a black hole. Here, we suggest that such implosions can happen in supra-massive neutron stars shortly (hundreds to thousands of seconds) after their births, and an observational signature of such implosions may have been observed in the X-ray afterglows of some long and short gamma-ray bursts (GRBs). Within this picture, a small fraction of FRBs would be physically connected to GRBs. We discuss possible multi-wavelength electromagnetic signals and gravitational wave signals that might be associated with FRBs, and propose an observational campaign to unveil the physical nature of FRBs. In particular, we strongly encourage a rapid radio follow-up observation of GRBs starting from 100 s after a GRB trigger

  7. Temporary epicardial cardiac resynchronisation versus conventional right ventricular pacing after cardiac surgery: study protocol for a randomised control trial

    Directory of Open Access Journals (Sweden)

    Russell Stuart J

    2012-02-01

    Full Text Available Abstract Background Heart failure patients with stable angina, acute coronary syndromes and valvular heart disease may benefit from revascularisation and/or valve surgery. However, the mortality rate is increased- 5-30%. Biventricular pacing using temporary epicardial wires after surgery is a potential mechanism to improve cardiac function and clinical endpoints. Method/design A multi-centred, prospective, randomised, single-blinded, intervention-control trial of temporary biventricular pacing versus standard pacing. Patients with ischaemic cardiomyopathy, valvular heart disease or both, an ejection fraction ≤ 35% and a conventional indication for cardiac surgery will be recruited from 2 cardiac centres. Baseline investigations will include: an electrocardiogram to confirm sinus rhythm and measure QRS duration; echocardiogram to evaluate left ventricular function and markers of mechanical dyssynchrony; dobutamine echocardiogram for viability and blood tests for renal function and biomarkers of myocardial injury- troponin T and brain naturetic peptide. Blood tests will be repeated at 18, 48 and 72 hours. The principal exclusions will be subjects with permanent atrial arrhythmias, permanent pacemakers, infective endocarditis or end-stage renal disease. After surgery, temporary pacing wires will be attached to the postero-lateral wall of the left ventricle, the right atrium and right ventricle and connected to a triple chamber temporary pacemaker. Subjects will be randomised to receive either temporary biventricular pacing or standard pacing (atrial inhibited pacing or atrial-synchronous right ventricular pacing for 48 hours. The primary endpoint will be the duration of level 3 care. In brief, this is the requirement for invasive ventilation, multi-organ support or more than one inotrope/vasoconstrictor. Haemodynamic studies will be performed at baseline, 6, 18 and 24 hours after surgery using a pulmonary arterial catheter. Measurements will be

  8. Cosmic-Rays and Gamma Ray Bursts

    Science.gov (United States)

    Meli, A.

    2013-07-01

    Cosmic-rays are subatomic particles of energies ranging between a few eV to hundreds of TeV. These particles register a power-law spectrum, and it seems that most of them originate from astrophysical galactic and extragalactic sources. The shock acceleration in superalfvenic astrophysical plasmas, is believed to be the main mechanism responsible for the production of the non-thermal cosmic-rays. Especially, the importance of the very high energy cosmic-ray acceleration, with its consequent gamma-ray radiation and neutrino production in the shocks of the relativistic jets of Gamma Ray Bursts, is a favourable theme of study. I will discuss the cosmic-ray shock acceleration mechanism particularly focusing on simulation studies of cosmic-ray acceleration occurring in the relativistic shocks of GRB jets.

  9. Heliospheric Origin of $\\gamma$-Ray Bursts

    CERN Document Server

    Li Ti Pei

    1997-01-01

    Systematic variations of average observational characteristics and correlation properties between different parameters of gamma-ray bursts (GRBs) with time from 1991 April to 1994 September are revealed. It is hard to explain the observed long-term variability by variations of experimental conditions. The variability of GRB properties with the time scale of months to years, together with the similarity between GRBs, solar hard X-ray flares and terrestrial gamma-ray flashes, may indicate an origin of GRBs, at least partly, within the heliosphere. Large-voltage and high-temperature pinch plasma columns produced by disruptive electrical discharges in the outer heliosphere can generate hard X-ray and gamma-ray flashes with energy spectra and spectral evolution characters consistent with that observed in GRBs.

  10. The ``Christmas burst'' GRB 101225A revisited

    Science.gov (United States)

    Thöne, C. C.; de Ugarte Postigo, A.; Fryer, C. L.; Kann, D. A.

    2015-03-01

    Long GRBs are related to the death of massive stars and reveal themselves through synchrotron emission from highly relativistic jets. The `Christmas Burst' GRB 101225A was an exceptionally long GRB with a thermal afterglow, very different from the standard GRB. Initially, no spectroscopic redshift could be obtained and SED modeling yielded z=0.33. A plausible model was a He-NS star merger where the He-star had ejected part of its envelope in the common envelope phase during inspiral. The interaction between the jet and the previously ejected shell can explains the thermal emission. We obtained deep spectroscopy of the host galaxy which leads to a correction of the redshift to z=0.847. Despite the higher redshift, our model is still valid and theoretically better justified than the alternative suggestion of a blue supergiant progenitor proposed by Levan et al. (2014) for several ``ultra-long'' GRBs.

  11. Critical Test Of Gamma Ray Burst Theories

    CERN Document Server

    Dado, Shlomo

    2016-01-01

    Long and precise follow-up measurements of the X-ray afterglow (AG) of very intense gamma ray bursts (GRBs) provide a critical test of GRB afterglow theories. Here we show that the power-law decline with time of X-ray AG of GRB 130427A, the longest measured X-ray AG of an intense GRB with the Swift, Chandra and XMM Newton satellites, and of all other well measured late-time X-ray afterglow of intense GRBs, is that predicted by the cannonball (CB) model of GRBs from their measured spectral index, while it disagrees with that predicted by the widely accepted fireball (FB) models of GRBs.

  12. Super Luminous Supernova and Gamma Ray Bursts

    CERN Document Server

    Dado, Shlomo

    2012-01-01

    We use a simple analytical model to derive a closed form expression for the bolometric light-curve of super-luminus supernovae (SLSNe) powered by a plastic collision between the fast ejecta from ordinary core collapse supernovae (SNe) of type Ib/c and slower massive circum-stellar shells, ejected in major eruptions of their progenitor stars during the late stage of their life preceding their SN explosion. We demonstrate that this expression reproduces well the bolometric luminosity of SLSNe with and without an observed gamma ray burst (GRB), and requires only a modest amount ($M\\lsim 0.1\\,M_\\odot$) of radioactive $^{56}$Ni synthesized in the SN explosion in order to explain their late-time luminosity. Ordinary stripped-envelope SNe of type Ib/c, rather than 'hypernovae', can produce most of the SLSNe and long duration GRBs.

  13. The Gamma Ray Bursts Hubble diagram

    CERN Document Server

    Capozziello, S; Dainotti, M G; De Laurentis, M; Izzo, L; Perillo, M

    2011-01-01

    Thanks to their enormous energy release, Gamma Rays Bursts (GRBs) have recently attracted a lot of interest to probe the Hubble diagram (HD) deep into the matter dominated era and hence complement Type Ia Supernovae (SNeIa). We consider here three different calibration methods based on the use of a fiducial LCDM model, on cosmographic parameters and on the local regression on SNeIa to calibrate the scaling relations proposed as an equivalent to the Phillips law to standardize GRBs finding any significant dependence. We then investigate the evolution of these parameters with the redshift to obtain any statistical improvement. Under this assumption, we then consider possible systematics effects on the HDs introduced by the calibration method, the averaging procedure and the homogeneity of the sample arguing against any significant bias.

  14. Gamma-Ray Bursts as Cosmological Tools

    CERN Document Server

    Petrosian, Vahe; Ryde, Felix

    2009-01-01

    In recent years there has been considerable activity in using gamma-ray bursts as cosmological probes for determining global cosmological parameters complementing results from type Ia supernovae and other methods. This requires a characteristics of the source to be a standard candle. We show that contrary to earlier indications the accumulated data speak against this possibility. Another method would be to use correlation between a distance dependent and a distance independent variable to measure distance and determine cosmological parameters as is done using Cepheid variables and to some extent Type Ia supernovae. Many papers have dealt with the use of so called Amati relation, first predicted by Lloyd, Petrosian and Mallozzi, or the Ghirlanda relation for this purpose. We have argued that these procedure involve many unjustified assumptions which if not true could invalidate the results. In particular, we point out that many evolutionary effects can affect the final outcome. In particular, we demonstrate th...

  15. The Euclidean distribution of fast radio bursts

    Science.gov (United States)

    Oppermann, Niels; Connor, Liam D.; Pen, Ue-Li

    2016-09-01

    We investigate whether current data on the distribution of observed flux densities of fast radio bursts (FRBs) are consistent with a constant source density in Euclidean space. We use the number of FRBs detected in two surveys with different characteristics along with the observed signal-to-noise ratios of the detected FRBs in a formalism similar to a V/Vmax-test to constrain the distribution of flux densities. We find consistency between the data and a Euclidean distribution. Any extension of this model is therefore not data-driven and needs to be motivated separately. As a byproduct we also obtain new improved limits for the FRB rate at 1.4 GHz, which had not been constrained in this way before.

  16. The Euclidean distribution of Fast Radio Bursts

    CERN Document Server

    Oppermann, Niels; Pen, Ue-Li

    2016-01-01

    We investigate whether current data on the distribution of observed flux densities of Fast Radio Bursts (FRBs) are consistent with a constant source density in Euclidean space. We use the number of FRBs detected in two surveys with different characteristics along with the observed signal-to-noise ratios of the detected FRBs in a formalism similar to a V/V_max-test to constrain the distribution of flux densities. We find consistency between the data and a Euclidean distribution. Any extension of this model is therefore not data-driven and needs to be motivated separately. As a byproduct we also obtain new improved limits for the FRB rate at 1.4 GHz, which had not been constrained in this way before.

  17. Directivity of X radiation of solar bursts

    International Nuclear Information System (INIS)

    To study the directivity of X radiation of solar bursts, the investigation into distributions of X-ray splashes over the range lambda=0.5-3 and 1-8 A in heliolongitudinal and intensity was carried on. The integral distribution of splashes in intensity has the exponential form with the exponent α approximately 1.1 and the bend on low intensities. In heliolongitudinal distribution the east-west asymmetry is observed. The absence of directivity of splash radiation is concluded on the basis of investigation of peculiarities of splash distribution functions in heliolongitude and intensity. The observed east-west asymmetry can't be connected with directivity, but is conditioned by probably by statistic fluctuations of the number of splashes

  18. High Energy Radiation from $\\gamma$ Ray Bursts

    CERN Document Server

    Dermer, C D; Dermer, Charles D.; Chiang, James

    1999-01-01

    Gamma-ray burst (GRB) engines are probed most intimately during the prompt gamma-ray luminous phase when the expanding blast wave is closest to the explosion center. Using GRBs 990123 and 940217 as guides, we briefly review observations of high-energy emission from GRBs and summarize some problems in GRB physics. \\gamma\\gamma transparency arguments imply relativistic beaming. The parameters that go into the external shock model are stated, and we show numerical simulation results of gamma-ray light curves from relativistic blast waves with different amounts of baryon loading. A distinct component due to the synchrotron self-Compton process produces significant emission at GeV and TeV energies. Predictions for spectral and temporal evolution at these energies are presented for a blast wave expanding into uniform surroundings. Observations of the slow decay of GeV-TeV radiation provide evidence for ultra-high energy cosmic ray acceleration in GRBs.

  19. Search for Gamma Ray Bursts at Chacaltaya

    CERN Document Server

    Vernetto, S

    2001-01-01

    A search for Gamma Ray Bursts in the GeV-TeV energy range has been performed by INCA, an air shower array working at 5200 m of altitude at the Chacaltaya Laboratory (Bolivia). The altitude of the detector and the use of the "single particle technique" allows to lower the energy threshold up to few GeVs. No significant signals are observed during the occurrence of 125 GRBs detected by BATSE, and the obtained upper limits on the energy fluence in the interval 1-1000(100) GeV range from 3.2(8.6) 10^-5 to 2.6(7.0) 10^-2 erg/cm^2 depending on the zenith angle of the events. These limits, thanks to the extreme altitude of INCA, are the lowest ever obtained in the sub-TeV energy region by a ground based esperiment.

  20. The Swift Burst and Transient Telescope (BAT)

    Science.gov (United States)

    Mushotzky, Richard

    2008-01-01

    The Swift Burst and Transient telescope (BAT) has surveyed the entire sky for the last 3.5 years obtaining the first sensitive all sky survey of the 14-195 kev sky. At high galactic latitudes the vast majority of the detected sources are AGN. Since hard x-rays penetrate all but Compton thick obscuring material (Column densities of 1.6324 atms/sq cm) this survey is unbiased with respect to obscuration, host galaxy type, optical , radio or IR properties. We will present results on the broad band x-ray properties, the nature of the host galaxies, the luminosity function and will discuss a few of the optical, IR and x-ray results in detail.

  1. Solution To The Gamma Ray Burst Mystery?

    CERN Document Server

    Dar, Arnon

    1996-01-01

    Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed $\\gamma$ rays along the flow direction. Repeated excitation/decay of highly relativistic baryonic ejecta from merger or accretion induced collapse of neutron stars in dense stellar regions (DSRs), like galactic cores, globular clusters and super star-clusters, can convert enough kinetic energy in such events in distant galaxies into cosmological gamma ray bursts (GRBs). The model predicts remarkably well all the main observed temporal and spectral properties of GRBs. Its success strongly suggests that GRBs are $\\gamma$ ray tomography pictures of DSRs in galaxies at cosmological distances with unprecedented resolution: A time resolution of $dt\\sim 1~ms$ in a GRB can resolve stars at a Hubble distance which are separated by only $D\\sim 10^{10}cm$. This is equivalent to the resolving power of an optica...

  2. Probing the Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope

    OpenAIRE

    Lien, Amy; Sakamoto, Takanori; Gehrels, Neil; Palmer, David M.; Barthelmy, Scott D.; Graziani, Carlo; Cannizzo, John K.

    2013-01-01

    The long gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early universe. While hundreds of GRBs are observed by Swift, it remains difficult to determine the intrinsic GRB rate due to the complex trigger algorithm of Swift. Current studies usually approximate the Swift trigger algorithm by a single detection threshold. However...

  3. Transcriptional burst frequency and burst size are equally modulated across the human genome

    OpenAIRE

    Dar, Roy D.; Razooky, Brandon S; Singh, Abhyudai; Trimeloni, Thomas V.; McCollum, James M.; Cox, Chris D.; Simpson, Michael L.; Weinberger, Leor S.

    2012-01-01

    Gene expression occurs either as an episodic process, characterized by pulsatile bursts, or as a constitutive process, characterized by a Poisson-like accumulation of gene products. It is not clear which mode of gene expression (constitutive versus bursty) predominates across a genome or how transcriptional dynamics are influenced by genomic position and promoter sequence. Here, we use time-lapse fluorescence microscopy to analyze 8,000 individual human genomic loci and find that at virtually...

  4. Effect of deceptively aggressive bike pacing on sprint-distance triathlon performance and associated perceptual responses

    OpenAIRE

    Taylor, Danny; Smith, Mark F.

    2015-01-01

    INTRODUCTION: Cycling at the highest sustainable intensity (i.e. isolated time-trial power output) is suggested as the best strategy to optimise sprint-distance triathlon performance (Suriano & Bishop, 2010, Eur J Appl Physiol, 110, 4:753-760). However, it is unclear how expectations, beliefs and perceptions influence the effectiveness of aggressive mid-event pacing during multi-modal endurance events. Taylor & Smith (2014, Physiol Behav, 133:45-52) suggest meaningful changes in triathlon per...

  5. Effect of deceptively aggressive bike pacing on sprint-distance triathlon performance

    OpenAIRE

    Taylor, Daniel; Smith, Mark F.

    2015-01-01

    Introduction: Whilst aggressive bike pacing has been found to impair subsequent run performance during triathlon, this strategy appears to enhance total cycle-run time over the sprint-distance format (Suriano & Bishop, 2010). As such, cycling at the highest sustainable intensity (i.e. isolated TT power output) is suggested as the best strategy to optimise overall performance time in the event. However, it is unclear how an athlete’s expectations, beliefs and perceptions influence the effectiv...

  6. Managing after-work stress: paced breathing while watching video content (abstract)

    OpenAIRE

    Tijs, T.J.W.; Weda, J.; Weffers-Albu, M.A.; Hoogenstraaten, W.

    2011-01-01

    Objectives. After a hard day’s work, we need to recover from work stress. Two frequently reported activities to relieve stress are television (TV) watching and paced breathing exercises. We investigated the potential of combining these techniques. Method. Two explorativeexperiments were conducted. In both experiments, stress was measured through physiological monitoring (heart rate, blood pressure, skinconductance, peripheral temperature, and respiration) and the Stress Arousal Checklist [3]....

  7. Reading sentences in Serbian: Effects of alphabet and reading mode in self-paced reading task

    OpenAIRE

    Vejnović Dušan; Jovanović Tamara

    2012-01-01

    The study examined the influence of alphabet (Cyrillic vs. Latin) and reading mode (silent reading vs. reading aloud) on sentence reading speed in Serbian. Entire-sentence and single-word reading times were obtained from the moving window paradigm in the self-paced sentence reading task. Sentences printed in Latin took less time for reading than sentences printed in Cyrillic and silent reading was more rapid than reading aloud. Single-word processing results followed the pattern observe...

  8. Response of atrial flutter to overdrive atrial pacing and intravenous disopyramide phosphate, singly and in combination.

    OpenAIRE

    Camm, J; Ward, D.; Spurrell, R

    1980-01-01

    Ten patients who suffered spontaneous paroxysms of atrial flutter were investigated by electrophysiological techniques. Two had overt Wolff-Parkinson-White syndrome; three Lown-Ganong-Levine syndrome; and one a concealed accessory atrioventricular connection. Atrial flutter was initiated, at study, by right atrial pacing and electrograms from the right atrium and coronary sinus were observed for at least five minutes to ensure stable flutter in both atria. Atrial flutter was terminated by 2.5...

  9. Hemodynamic Surveillance of Ventricular Pacing Effectiveness with the Transvalvular Impedance Sensor

    OpenAIRE

    Valeria Calvi; Giovanni Pizzimenti; Marco Lisi; Giuseppe Doria; Ludovico Vasquez; Francesco Lisi; Salvatore Felis; Donatella Tempio; Alfredo Virgilio; Alberto Barbetta; Franco Di Gregorio

    2014-01-01

    The Transvalvular Impedance (TVI) is derived between atrial and ventricular pacing electrodes. A sharp TVI increase in systole is an ejection marker, allowing the hemodynamic surveillance of ventricular stimulation effectiveness in pacemaker patients. At routine follow-up checks, the ventricular threshold test was managed by the stimulator with the supervision of a physician, who monitored the surface ECG. When the energy scan resulted in capture loss, the TVI system must detect the failure a...

  10. Explaining the Slow Pace of Energy Technological Innovation: Why Market Conditions Matter

    OpenAIRE

    Jin, Wei; Zhang, ZhongXiang

    2014-01-01

    As a useful complement to numerous innovation policy studies from a normative perspective, this paper provides a positive framework to analyze the basic economic mechanism of energy technological innovation and explains its slow pace of technological progress. We find that the capital-intensiveness of energy technology is an inhibiting factor to catalyze market size effect and slows innovations and diffusions of energy technology in the market. We also show that the substantial homogeneity of...

  11. Predicting Number of Zombies in DDoS Attacks Using Pace Regression Model

    OpenAIRE

    Gupta, B. B.

    2012-01-01

    A DDoS attacker attempts to disrupt a target, by flooding it with illegitimate packets which are generated from a large number of zombies, usurping its bandwidth and overtaxing it to prevent legitimate inquiries from getting through. This paper reports the evaluation results of proposed approach that is used to predict number of zombies using Pace Regression Model. A relationship is established between number of zombies and observed deviation in sample entropy. Various statistical performance...

  12. Self-directed/self-paced learning using course templates and community modules

    OpenAIRE

    Tannant, Maria

    2014-01-01

    With UCA based across 5 campuses and 2 learning technologists to manage the university's Virtual Learning Environment (VLE), this presentation offers a window into how they have developed a mechanism and collection of self-directed/self-paced learning resources for both students and faculty staff. These learning resources are applied to the course templates at the start of each academic year. Template content for students include: Digital literacy skills, professional networking, buil...

  13. The impact of the perception of rhythmic music on self-paced oscillatory movements.

    Science.gov (United States)

    Peckel, Mathieu; Pozzo, Thierry; Bigand, Emmanuel

    2014-01-01

    Inspired by theories of perception-action coupling and embodied music cognition, we investigated how rhythmic music perception impacts self-paced oscillatory movements. In a pilot study, we examined the kinematic parameters of self-paced oscillatory movements, walking and finger tapping using optical motion capture. In accordance with biomechanical constraints accounts of motion, we found that movements followed a hierarchical organization depending on the proximal/distal characteristic of the limb used. Based on these findings, we were interested in knowing how and when the perception of rhythmic music could resonate with the motor system in the context of these constrained oscillatory movements. In order to test this, we conducted an experiment where participants performed four different effector-specific movements (lower leg, whole arm and forearm oscillation and finger tapping) while rhythmic music was playing in the background. Musical stimuli consisted of computer-generated MIDI musical pieces with a 4/4 metrical structure. The musical tempo of each song increased from 60 BPM to 120 BPM by 6 BPM increments. A specific tempo was maintained for 20 s before a 2 s transition to the higher tempo. The task of the participant was to maintain a comfortable pace for the four movements (self-paced) while not paying attention to the music. No instruction on whether to synchronize with the music was given. Results showed that participants were distinctively influenced by the background music depending on the movement used with the tapping task being consistently the most influenced. Furthermore, eight strategies put in place by participants to cope with the task were unveiled. Despite not instructed to do so, participants also occasionally synchronized with music. Results are discussed in terms of the link between perception and action (i.e., motor/perceptual resonance). In general, our results give support to the notion that rhythmic music is processed in a motoric

  14. The impact of the perception of rhythmic music on oscillatory self-paced movements

    Directory of Open Access Journals (Sweden)

    Mathieu ePeckel

    2014-09-01

    Full Text Available Inspired by theories of perception-action coupling and embodied music cognition, we investigated how rhythmic music perception impacts self-paced oscillatory movements. In a pilot study, we examined the kinematic parameters of self-paced oscillatory movements, walking and finger tapping using optical motion capture. In accordance with biomechanical constraints accounts of motion, we found that movements followed a hierarchical organization depending on the proximal/distal characteristic of the limb used. Based on these findings, we were interested in knowing how and when the perception of rhythmic music could resonate with the motor system in the context of these constrained oscillatory movements. In order to test this, we conducted an experiment where participants performed four different effector-specific movements (lower leg, whole arm and forearm oscillation and finger tapping while rhythmic music was playing in the background. Musical stimuli consisted of computer-generated MIDI musical pieces with a 4/4 metrical structure. The musical tempo of each song increased from 60 BPM to 120 BPM by 6 BPM increments. A specific tempo was maintained for 20s before a 2s transition to the higher tempo. The task of the participant was to maintain a comfortable pace for the four movements (self-paced while not paying attention to the music. No instruction on whether to synchronize with the music was given. Results showed that participants were distinctively influenced by the background music depending on the movement used with the tapping task being consistently the most influenced. Furthermore, eight strategies put in place by participants to cope with task were unveiled. Despite not instructed to do so, participants also occasionally synchronized with music. Results are discussed in terms of the link between perception and action (i.e. motor/perceptual resonance. In general, our results give support to the notion that rhythmic music is processed in a

  15. Social marketing of a different pace: between liberal and paternalistic management of social change:

    OpenAIRE

    Kamin, Tanja

    2011-01-01

    This article examines social marketing as one of the approaches for managing social change. We place the concept of social marketing on the continuum between liberal and paternalistic approaches to social change management. Furthermore, we consider which forms of social change management in Slovenia are dominant, and in which position among them is social marketing. The presumption of the discussion is that social marketing has developed at different paces and with different acknowledgements ...

  16. Potential Effect of Physical Activity Calorie Equivalent (PACE) Labeling on Adult Fast Food Ordering and Exercise

    OpenAIRE

    Ray Antonelli; Viera, Anthony J.

    2015-01-01

    Introduction Numeric calorie content labels show limited efficacy in reducing the number of calories ordered from fast food meals. Physical activity calorie equivalent (PACE) labels are an alternative that may reduce the number of calories ordered in fast food meals while encouraging patrons to exercise. Methods A total of 1000 adults from 47 US states were randomly assigned via internet survey to one of four generic fast food menus: no label, calories only, calories + minutes, or calories + ...

  17. The pace of MNEs’ sequential entries: Cumulative entry experience and the dynamic process

    OpenAIRE

    Gerald Yong Gao; Yigang Pan

    2010-01-01

    This study examines the pace with which multinational enterprises undertake sequential entries in a foreign market. We focus on learning effects from cumulative entry experience of different modes within a host market. Moreover, we investigate the dynamic process of entry mode switch, and how cumulative entry experience reduces the expansion constraint. Using a dataset of sequential entries by US firms in China during 1979–2002, we find that the impact of cumulative entry experience on the pa...

  18. Preoperative evaluation of cardiac risk by means of atrial pacing and thallium 201 scintigraphy

    International Nuclear Information System (INIS)

    Atrial pacing and thallium 201 scintigraphy were done in 61 patients with known or suspected coronary artery disease referred for evaluation of cardiac risk before elective vascular surgery. All patients had noncardiac limitations precluding performance of an adequate exercise stress test. Before atrial pacing all were considered to be at low risk of a postoperative cardiac event based on assessment of clinical parameters. Vascular surgery was subsequently performed in 47 patients. In these patients, pacing-induced ST segment depression greater than or equal to 1 mm occurred in 18, a fixed perfusion defect occurred in 11, and a reversible defect occurred in six. Two of the six patients with reversible perfusion defects had preoperative coronary angiography; both had significant coronary artery disease (one or more lesions greater than or equal to 50%). Two patients (one of whom had a reversible perfusion defect) underwent preoperative coronary revascularization and tolerated subsequent vascular surgery well. All other patients received only medical therapy. None of the 47 patients undergoing vascular surgery had a postoperative cardiac event (unstable angina, congestive heart failure, myocardial infarction, or cardiac death). Of the 14 patients in whom vascular surgery was deferred or canceled, surgery was canceled for noncardiac reasons in seven. Six of these seven patients had a normal perfusion scan; none had a reversible perfusion defect or marked (greater than or equal to 2 mm) ST segment depression. No cardiac event occurred during a 3-month period after atrial pacing in any of these patients. Six of the remaining seven patients had reversible perfusion defects

  19. Differential effects of prolonged work on performance measures in self-paced speed tests.

    OpenAIRE

    Steinborn, Michael B.; HAGEN C. FLEHMIG; Westhoff, Karl; Langner, Robert

    2010-01-01

    Time-related changes in the speeded performance of complex cognitive tasks are considered to arise from the combined effects of practice and mental fatigue. Here we explored the differential contributions of practice and fatigue to performance changes in a self-paced speeded mental addition and comparison task of about 50 min duration, administered twice within one week’s time. Performance measures included average response speed, accuracy, and response speed variability. The results revealed...

  20. TREATMENT PLANNING, PACING, AND COUNTERTRANSFERENCE: PERSPECTIVES ON THE PSYCHOTHERAPY OF EARLY AFFECT-CONFUSION

    Directory of Open Access Journals (Sweden)

    Richard G. Erskine

    2012-12-01

    Full Text Available This article is a rejoinder and elaboration on the article “Early Affect-Confusion: The ‘Borderline’ Between Despair and Rage: Part 1 of a Case Study Trilogy” and addresses the distinction between personality style, pattern, and disorder. It describes the pacing of a time-limited psychotherapy, the use of phenomenological inquiry in resolving transferential enactments, and the psychological function of idealization.

  1. RETARDATION OF PACE OF LIFE AND RESOURCES TRANSFORMATION – SOME IMPLICATIONS OF CITIZENS

    OpenAIRE

    Joanna Kostecka

    2014-01-01

    The article attempts to explain the term retardation of pace of life and transforming natural resources, highlights the complexity of the concept and presents proposals for action for its dissemination. Retardation of resources transformation is an important tool for the implementation of the new approach on those environmental resources and services that are left. Environmental education that supports the implementation of retardation should use active methods of education and should be inte...

  2. Induction of atrial fibrillation with rapid high voltage ventricular pacing for ventricular fibrillation conversion testing

    OpenAIRE

    Schuchert, A; Kuhl, M; Ruppel, R; Meinertz, T

    2000-01-01

    OBJECTIVE—To assess whether rapid high voltage ventricular pacing can also induce atrial fibrillation, and whether the induction of atrial fibrillation during ventricular fibrillation conversion testing is related to the patient's heart disease.
DESIGN—Prospective study of 50 patients who received the dual chamber implantable cardioverter-defibrillator (ICD) Ventak AV II DR (Guidant) as a first implant. This device can record atrial activity even during a ventricular fibrillation episode and ...

  3. PACE: Pattern Accurate Computationally Efficient Bootstrapping for Timely Discovery of Cyber-Security Concepts

    OpenAIRE

    McNeil, Nikki; Bridges, Robert A.; Iannacone, Michael D.; Czejdo, Bogdan; Perez, Nicolas; Goodall, John R.

    2013-01-01

    Public disclosure of important security information, such as knowledge of vulnerabilities or exploits, often occurs in blogs, tweets, mailing lists, and other online sources months before proper classification into structured databases. In order to facilitate timely discovery of such knowledge, we propose a novel semi-supervised learning algorithm, PACE, for identifying and classifying relevant entities in text sources. The main contribution of this paper is an enhancement of the traditional ...

  4. Gamma-ray bursts and collisionless shocks

    Science.gov (United States)

    Waxman, E.

    2006-12-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from a few GeV to > 1020 eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of γ-ray burst (GRB) 'afterglows' provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars. Their 'afterglows', delayed low energy emission following the prompt burst of γ-rays, are well accounted for by a model in which afterglow radiation is due to synchrotron emission of electrons accelerated in relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Within the framework of this model, some striking characteristics of collisionless relativistic shocks are implied. These include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ~1010 skin-depths downstream of the shock and the acceleration of particles to a power-law energy spectrum, d log n/d logɛ ap -2, possibly extending to 1020 eV. I review in this talk the phenomenological considerations, based on which these characteristics are inferred, and the challenges posed to our current models of particle acceleration and magnetic field generation in collisionless shocks. Some recent theoretical results derived based on the assumption of a self-similar shock structure are briefly discussed. Invited review presented at the 33rd annual European Physical Society Conference, Rome, 2006.

  5. 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

  6. SGR J1550-5418 Bursts Detected with the Fermi Gamma-Ray Burst Monitor during Its Most Prolific Activity

    Science.gov (United States)

    vanderHorst, A. J.; Kouveliotou, C.; Gorgone, N. M.; Kaneko, Y.; Baring, M. G.; Guiriec, S.; Gogus, E,; Granot, J.; Watts, A. L.; Lin, L.; Bhat, P. N.; Bissaldi, E.; Chaplin, V. L.; Finger, M. H.; Gehrels, N.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Gruber, D.; Harding, A. K.; McEnery, J.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Wilson-Hodge, C.

    2012-01-01

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties.We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J15505418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E(sub peak) and the burst fluence and average flux. For the BB+BBfits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature.We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

  7. SGR J1550-5418 BURSTS DETECTED WITH THE FERMI GAMMA-RAY BURST MONITOR DURING ITS MOST PROLIFIC ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Van der Horst, A. J.; Finger, M. H. [Universities Space Research Association, NSSTC, Huntsville, AL 35805 (United States); Kouveliotou, C. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gorgone, N. M. [Connecticut College, New London, CT 06320 (United States); Kaneko, Y.; Goegues, E.; Lin, L. [Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, Istanbul 34956 (Turkey); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Guiriec, S.; Bhat, P. N.; Chaplin, V. L.; Goldstein, A. [University of Alabama, Huntsville, CSPAR, Huntsville, AL 35805 (United States); Granot, J. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Watts, A. L. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Bissaldi, E.; Gruber, D. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, 85748 Garching (Germany); Gehrels, N.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gibby, M. H.; Giles, M. M., E-mail: A.J.VanDerHorst@uva.nl [Jacobs Technology, Inc., Huntsville, AL (United States); and others

    2012-04-20

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E{sub peak} and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

  8. Closest Gamma Ray Burst Providing Scientists With Crucial Test for Burst Physics

    Science.gov (United States)

    2003-05-01

    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

  9. The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts

    CERN Document Server

    Evans, P A; Osborne, J P; O'Brien, P T; Page, K L; Markwardt, C B; Barthelmy, S D; Beardmore, A P; Burrows, D N; Pagani, C; Starling, R L C; Romano, P

    2010-01-01

    Context: Gamma Ray Burst models predict the broadband spectral evolution and the temporal evolution of the energy flux. In contrast, standard data analysis tools and data repositories provide count-rate data, or use single flux conversion factors for all of the data, neglecting spectral evolution. Aims: To produce Swift BAT and XRT light curves in flux units, where the spectral evolution is accounted for. Methods: We have developed software to use the hardness ratio information to track spectral evolution of GRBs, and thus to convert the count-rate light curves from the BAT and XRT instruments on Swift into accurate, evolution-aware flux light curves. Results: The Swift Burst Analyser website (http://www.swift.ac.uk/burst_analyser) contains BAT, XRT and combined BAT-XRT flux light curves in three energy regimes for all GRBs observed by the Swift satellite. These light curves are automatically built and updated when data become available, are presented in graphical and plain-text format, and are available for ...

  10. Migration of a retained temporary epicardial pacing wire into an abdominal aortic aneurysm.

    Science.gov (United States)

    Mukaihara, Kosuke; Yotsumoto, Goichi; Matsumoto, Kazuhisa; Imoto, Yutaka

    2015-07-01

    A 69-year old male was referred to our hospital for the treatment of coronary artery disease. Preoperative computed tomography (CT) revealed an abdominal aortic aneurysm (AAA) and a giant tumour of the left kidney. He underwent off-pump coronary artery bypass grafting (OPCAB) prior to aneurysmectomy and nephrectomy. Temporary epicardial pacing wires (TEPWs) were placed on the right atrium and right ventricle. The bipolar ventricular wire was removed and the unipolar atrial wire was cut flush with the skin surface on postoperative day 5. CT 7 days after the OPCAB procedure revealed a retained TEPW sutured to the right atrial wall. One month later, the patient underwent a repair of the AAA and left nephrectomy. We found that a TEPW had migrated inside the AAA intraoperatively. The retained TEPW was thus no longer observed on postoperative CT. Migration of the atrial pacing wire through the aortic lumen was suspected, although the detailed mechanism is unknown. This is the first reported case of a migrated temporary pacing wire into the aorta under noninfectious conditions. PMID:25173602

  11. Spontaneous Velocity Effect of Musical Expression on Self-Paced Walking.

    Science.gov (United States)

    Buhmann, Jeska; Desmet, Frank; Moens, Bart; Van Dyck, Edith; Leman, Marc

    2016-01-01

    The expressive features of music can influence the velocity of walking. So far, studies used instructed (and intended) synchronization. But is this velocity effect still present with non-instructed (spontaneous) synchronization? To figure that out, participants were instructed to walk in their own comfort tempo on an indoor track, first in silence and then with tempo-matched music. We compared velocities of silence and music conditions. The results show that some music has an activating influence, increasing velocity and motivation, while other music has a relaxing influence, decreasing velocity and motivation. The influence of musical expression on the velocity of self-paced walking can be predicted with a regression model using only three sonic features explaining 56% of the variance. Phase-coherence between footfall and beat did not contribute to the velocity effect, due to its implied fixed pacing. The findings suggest that the velocity effect depends on vigor entrainment that influences both stride length and pacing. Our findings are relevant for preventing injuries, for gait improvement in walking rehabilitation, and for improving performance in sports activities. PMID:27167064

  12. Spontaneous Velocity Effect of Musical Expression on Self-Paced Walking.

    Directory of Open Access Journals (Sweden)

    Jeska Buhmann

    Full Text Available The expressive features of music can influence the velocity of walking. So far, studies used instructed (and intended synchronization. But is this velocity effect still present with non-instructed (spontaneous synchronization? To figure that out, participants were instructed to walk in their own comfort tempo on an indoor track, first in silence and then with tempo-matched music. We compared velocities of silence and music conditions. The results show that some music has an activating influence, increasing velocity and motivation, while other music has a relaxing influence, decreasing velocity and motivation. The influence of musical expression on the velocity of self-paced walking can be predicted with a regression model using only three sonic features explaining 56% of the variance. Phase-coherence between footfall and beat did not contribute to the velocity effect, due to its implied fixed pacing. The findings suggest that the velocity effect depends on vigor entrainment that influences both stride length and pacing. Our findings are relevant for preventing injuries, for gait improvement in walking rehabilitation, and for improving performance in sports activities.

  13. The influence of performance level, age and gender on pacing strategy during a 100-km ultramarathon.

    Science.gov (United States)

    Renfree, Andrew; Crivoi do Carmo, Everton; Martin, Louise

    2016-01-01

    The aim of this study is to analyse the influence of performance level, age and gender on pacing during a 100-km ultramarathon. Results of a 100-km race incorporating the World Masters Championships were used to identify differences in relative speeds in each 10-km segment between participants finishing in the first, second, third and fourth quartiles of overall positions (Groups 1, 2, 3 and 4, respectively). Similar analyses were performed between the top and bottom 50% of finishers in each age category, as well as within male and female categories. Pacing varied between athletes achieving different absolute performance levels. Group 1 ran at significantly lower relative speeds than all other groups in the first three 10-km segments (all P bottom' competitors in the early stages, but higher relative speeds in the later stages. Females showed lower relative starting speeds and higher finishing speeds than males. 'Top' and 'bottom' finishing males displayed differing strategies, but this was not the case within females. Although pacing remained consistent across age categories, it differed with level of performance within each, possibly suggesting strategies are anchored on direct competitors. Strategy differs between genders and differs depending on performance level achieved in males but not females. PMID:26034882

  14. The distribution of pace adopted by cyclists during a cross-country mountain bike World Championships.

    Science.gov (United States)

    Abbiss, Chris R; Ross, Megan L R; Garvican, Laura A; Ross, Neil; Pottgiesser, Torben; Gregory, John; Martin, David T

    2013-01-01

    The purpose of this study was to examine the distribution of pace self-selected by cyclists of varying ability, biological age and sex performing in a mountain bike World Championship event. Data were collected on cyclists performing in the Elite Male (ELITEmale; n = 75), Elite Female (ELITEfemale; n = 50), Under 23 Male (U23male; n = 62), Under 23 Female (U23female; n = 34), Junior Male (JNRmale; n = 71) and Junior Female (JNRfemale; n = 30) categories of the 2009 UCI Cross-Country Mountain Bike World Championships. Split times were recorded for the top, middle and bottom 20% of all finishers of each category. Timing splits were positioned to separate the course into technical and non-technical, uphill, downhill and rolling/flat sections. Compared with bottom performers, top performers in all male categories (ELITEmale, U23male, JNRmale) maintained a more even pace over the event as evidenced by a significantly lower standard deviation and range in average lap speed. Top performers, males, and ELITEmale athletes spent a lower percentage of overall race time on technical uphill sections of the course, compared with middle and bottom placed finishers, females, and JNRmale athletes, respectively. Better male performers adopt a more even distribution of pace throughout cross-country mountain events. Performance of lower placed finishers, females and JNRmale athletes may be improved by enhancing technical uphill cycling ability. PMID:23521618

  15. Efficacy of paced breathing for insomnia: enhances vagal activity and improves sleep quality.

    Science.gov (United States)

    Tsai, H J; Kuo, Terry B J; Lee, Guo-She; Yang, Cheryl C H

    2015-03-01

    Fourteen self-reported insomniacs (SRI) and 14 good sleepers (GS) had their cardiac neuronal activity assessed by heart rate variability (HRV) under controlled respiration at a slow frequency rate of 0.1 Hz, and a forced rate of 0.2 Hz during daytime rest. Nighttime sleep was measured by polysomnography. The SRI showed depressed high frequency power of HRV compared to the GS. An increased total power of HRV was observed among the SRI during slow, paced breathing compared with spontaneous breathing and 0.2 Hz. Sleep onset latency, number of awakenings, and awakening time during sleep were decreased and sleep efficiency was increased if SRI practiced slow, paced breathing exercises for 20 min before going to sleep. Our results indicate that there is autonomic dysfunction among insomniacs, especially in relation to vagal activity; however, this decreased vagal activity can be facilitated by practicing slow, paced breathing, thereby improving sleep quality. PMID:25234581

  16. A positron emission tomography study of self-paced finger movements at different frequencies

    International Nuclear Information System (INIS)

    Regional cerebral blood flow was measured in six right-handed volunteers using positron emission tomography during tasks involving repetitive self-paced finger tapping at five different frequencies. The contralateral primary sensorimotor cortex, the pre-supplementary motor area and the cingulate motor area showed significant activation during self-paced finger tapping tasks, compared with the resting state. A positive correlation between the regional cerebral blood flow and the movement frequency was found only in the primary sensorimotor cortex. In the pre-supplementary motor area and the cingulate motor area, however, activity increased when the subject employed movement frequencies faster or slower than his own pace. The same tendency was noted with respect to the relative variability of the inter-tapping interval.The results therefore indicate that the activity of the pre-supplementary motor area and the cingulate motor area may well be related to the increased difficulty in motor control rather than to the execution of the movement itself. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. Spontaneous Velocity Effect of Musical Expression on Self-Paced Walking

    Science.gov (United States)

    Buhmann, Jeska; Desmet, Frank; Moens, Bart; Van Dyck, Edith; Leman, Marc

    2016-01-01

    The expressive features of music can influence the velocity of walking. So far, studies used instructed (and intended) synchronization. But is this velocity effect still present with non-instructed (spontaneous) synchronization? To figure that out, participants were instructed to walk in their own comfort tempo on an indoor track, first in silence and then with tempo-matched music. We compared velocities of silence and music conditions. The results show that some music has an activating influence, increasing velocity and motivation, while other music has a relaxing influence, decreasing velocity and motivation. The influence of musical expression on the velocity of self-paced walking can be predicted with a regression model using only three sonic features explaining 56% of the variance. Phase-coherence between footfall and beat did not contribute to the velocity effect, due to its implied fixed pacing. The findings suggest that the velocity effect depends on vigor entrainment that influences both stride length and pacing. Our findings are relevant for preventing injuries, for gait improvement in walking rehabilitation, and for improving performance in sports activities. PMID:27167064

  18. Atrioventricular Junction Ablation in Atrial Fibrillation: Choosing The Right Patient and Pacing Device

    Directory of Open Access Journals (Sweden)

    Finn Akerstr�m; Mois�s Rodr�guez-Ma�ero; Marta Pach�n; Alberto Puchol; X. Alberte Fern�ndez-L�pez; Luis Mart�nez-Sande; Miguel Valderr�bano MD; Miguel A. Arias.

    2015-08-01

    Full Text Available Atrial fibrillation (AF is the most common cardiac arrhythmia and despite advancements in rhythm control through direct catheter ablation, maintaining sinus rhythm is currently not possible in a large proportion of AF patients. Furthermore, in some instances pharmacological rate control may be insufficient, resulting in a highly symptomatic patient at risk of developing tachycardia-induced cardiomyopathy and heart failure (HF. Catheter ablation of the atrioventricular junction (AVJ with subsequent permanent pacemaker implantation provides definite rate control and represents an attractive therapeutic option when pharmacological rate control is not achieved. In those with reduced ventricular function, cardiac resynchronization therapy (CRT should be considered over right ventricular apical (RVA pacing in order to avoid the deleterious effects associated with a high amount of chronic RVA pacing. Another group of patients that may also benefit from AVJ ablation are HF patients with concomitant AF receiving CRT. In this patient cohort AVJ ablation ensures near 100% biventricular pacing, thus allowing optimization of the therapeutic effects of CRT.

  19. Strange Nonchaotic Bursting in A Quasiperiodially-Forced Hindmarsh-Rose Neuron

    CERN Document Server

    Lim, Woochang; 10.3938/jkps57.1356

    2011-01-01

    We study the transition from a silent state to a bursting state by varying the dc stimulus in the Hindmarsh-Rose neuron under quasiperiodic stimulation. For this quasiperiodically forced case, a new type of strange nonchaotic (SN) bursting state is found to occur between the silent state and the chaotic bursting state. This is in contrast to the periodically forced case where the silent state transforms directly to a chaotic bursting state. Using a rational approximation to the quasiperiodic forcing, the mechanism for the appearance of such an SN bursting state is investigated. Thus, a smooth torus (corresponding to a silent state) is found to transform to an SN bursting attractor through a phase-dependent subcritical period-doubling bifurcation. These SN bursting states, together with chaotic bursting states, are characterized in terms of the interburst interval, the bursting length, and the number of spikes in each burst. Both bursting states are found to be aperiodic complex ones. Consequently, aperiodic c...

  20. Full system bifurcation analysis of endocrine bursting models.

    Science.gov (United States)

    Tsaneva-Atanasova, Krasimira; Osinga, Hinke M; Riess, Thorsten; Sherman, Arthur

    2010-06-21

    Plateau bursting is typical of many electrically excitable cells, such as endocrine cells that secrete hormones and some types of neurons that secrete neurotransmitters. Although in many of these cell types the bursting patterns are regulated by the interplay between voltage-gated calcium channels and calcium-sensitive potassium channels, they can be very different. We investigate so-called square-wave and pseudo-plateau bursting patterns found in endocrine cell models that are characterized by a super- or subcritical Hopf bifurcation in the fast subsystem, respectively. By using the polynomial model of Hindmarsh and Rose (Proceedings of the Royal Society of London B 221 (1222) 87-102), which preserves the main properties of the biophysical class of models that we consider, we perform a detailed bifurcation analysis of the full fast-slow system for both bursting patterns. We find that both cases lead to the same possibility of two routes to bursting, that is, the criticality of the Hopf bifurcation is not relevant for characterizing the route to bursting. The actual route depends on the relative location of the full-system's fixed point with respect to a homoclinic bifurcation of the fast subsystem. Our full-system bifurcation analysis reveals properties of endocrine bursting that are not captured by the standard fast-slow analysis. PMID:20307553