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Sample records for burst can detection

  1. How Else Can We Detect Fast Radio Bursts?

    Science.gov (United States)

    Lyutikov, Maxim; Lorimer, Duncan R.

    2016-06-01

    We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. However, magnetar giant flares, driven by the reconfiguration of the magnetosphere, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission, (ii) a contemporaneous optical flash that can reach naked eye peak luminosity (but only for a few milliseconds), and (iii) a high-energy afterglow emission. Case (i) could be tested by coordinated radio and high-energy experiments. Case (ii) could be seen in a coordinated radio-optical surveys, e.g., by the Palomar Transient Factory in a 60 s frame as a transient object of m = 15-20 mag with an expected optical detection rate of about 0.1 hr-1, an order of magnitude higher than in radio. Shallow, but large-area sky surveys such as ASAS-SN and EVRYSCOPE could also detect prompt optical flashes from the more powerful Lorimer-burst clones. The best constraints on the optical to radio power for this kind of emission could be provided by future observations with facilities like Large Synoptic Survey Telescope. Case (iii) might be seen in relatively rare cases that the relativistically ejected magnetic blob is moving along the line of sight.

  2. How else can we detect Fast Radio Bursts?

    CERN Document Server

    Lyutikov, Maxim

    2016-01-01

    We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. Magnetar giant flares, driven by the reconfiguration of the magnetosphere, however, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission; (ii) a contemporaneous optical flash that can reach naked eye peak luminosity (but only for a few milliseconds); (iii) a high energy afterglow emission. Case (i) could be tested by coordinated radio and high-energy experiments. Case (ii) could be seen by the Palomar Transient Factory in a 60-second frame as a transient object of $m=15-20$ magnitude with an expected optical detection rate of about 0.1~hr$^{-1}$, an order of magnitude higher than in radio. EVRYSCOPE could also ...

  3. Gravitational-wave bursts from soft gamma-ray repeaters Can they be detected?

    CERN Document Server

    Cuesta, H J M; Aguiar, O D; Horváth, J E

    1998-01-01

    In this letter we suggest a scenario for simultaneous emission of gravitational-wave and $\\gamma$-ray bursts (GRBs) from soft gamma-ray repeaters (SGRs). we argue that both of the radiations can be generated by a super-Eddington accreting neutron stars in X-ray binaries. In this model a supercritical accretion transient takes back onto the remnant star the disk leftover by the hydrodynamic instability phase of a low magnetized, rapidly rotating neutron star in a X-ray binary system. We estimate the rise timescale effective associated temperature $T_{eff} = 740 keV$, and the timescale for repeating a burst of $\\gamma$-rays $\\Delta \\tau_R = 11.3 yr$. Altogether, we find the associated GW amplitude and frequency to be $h_c = 2.7 \\times 10^{-23}/{(Hz)}^{1/2}$ and $f_{gw} = 966 Hz$, for a source distance $\\sim 55 kpc$. Detectability of the pulses by t he forthcoming GW anntenas is discussed and found likely.

  4. Arc burst pattern analysis fault detection system

    Science.gov (United States)

    Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

    1997-01-01

    A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

  5. Detection of artifacts from high energy bursts in neonatal EEG.

    Science.gov (United States)

    Bhattacharyya, Sourya; Biswas, Arunava; Mukherjee, Jayanta; Majumdar, Arun Kumar; Majumdar, Bandana; Mukherjee, Suchandra; Singh, Arun Kumar

    2013-11-01

    Detection of non-cerebral activities or artifacts, intermixed within the background EEG, is essential to discard them from subsequent pattern analysis. The problem is much harder in neonatal EEG, where the background EEG contains spikes, waves, and rapid fluctuations in amplitude and frequency. Existing artifact detection methods are mostly limited to detect only a subset of artifacts such as ocular, muscle or power line artifacts. Few methods integrate different modules, each for detection of one specific category of artifact. Furthermore, most of the reference approaches are implemented and tested on adult EEG recordings. Direct application of those methods on neonatal EEG causes performance deterioration, due to greater pattern variation and inherent complexity. A method for detection of a wide range of artifact categories in neonatal EEG is thus required. At the same time, the method should be specific enough to preserve the background EEG information. The current study describes a feature based classification approach to detect both repetitive (generated from ECG, EMG, pulse, respiration, etc.) and transient (generated from eye blinking, eye movement, patient movement, etc.) artifacts. It focuses on artifact detection within high energy burst patterns, instead of detecting artifacts within the complete background EEG with wide pattern variation. The objective is to find true burst patterns, which can later be used to identify the Burst-Suppression (BS) pattern, which is commonly observed during newborn seizure. Such selective artifact detection is proven to be more sensitive to artifacts and specific to bursts, compared to the existing artifact detection approaches applied on the complete background EEG. Several time domain, frequency domain, statistical features, and features generated by wavelet decomposition are analyzed to model the proposed bi-classification between burst and artifact segments. A feature selection method is also applied to select the

  6. DETECTING THE SUPERNOVA BREAKOUT BURST IN TERRESTRIAL NEUTRINO DETECTORS

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, Joshua; Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dolence, Joshua C., E-mail: joshuajw@astro.princeton.edu [Computational Physics Group (CCS-2), MS-K784, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

    2016-02-01

    We calculate the distance-dependent performance of a few representative terrestrial neutrino detectors in detecting and measuring the properties of the ν{sub e} breakout burst light curve in a Galactic core-collapse supernova. The breakout burst is a signature phenomenon of core collapse and offers a probe into the stellar core through collapse and bounce. We examine cases of no neutrino oscillations and oscillations due to normal and inverted neutrino-mass hierarchies. For the normal hierarchy, other neutrino flavors emitted by the supernova overwhelm the ν{sub e} signal, making a detection of the breakout burst difficult. For the inverted hierarchy (IH), some detectors at some distances should be able to see the ν{sub e} breakout burst peak and measure its properties. For the IH, the maximum luminosity of the breakout burst can be measured at 10 kpc to accuracies of ∼30% for Hyper-Kamiokande (Hyper-K) and ∼60% for the Deep Underground Neutrino Experiment (DUNE). Super-Kamiokande (Super-K) and Jiangmen Underground Neutrino Observatory (JUNO) lack the mass needed to make an accurate measurement. For the IH, the time of the maximum luminosity of the breakout burst can be measured in Hyper-K to an accuracy of ∼3 ms at 7 kpc, in DUNE to ∼2 ms at 4 kpc, and JUNO and Super-K can measure the time of maximum luminosity to an accuracy of ∼2 ms at 1 kpc. Detector backgrounds in IceCube render a measurement of the ν{sub e} breakout burst unlikely. For the IH, a measurement of the maximum luminosity of the breakout burst could be used to differentiate between nuclear equations of state.

  7. Detection of bursts and pauses in spike trains.

    Science.gov (United States)

    Ko, D; Wilson, C J; Lobb, C J; Paladini, C A

    2012-10-15

    Midbrain dopaminergic neurons in vivo exhibit a wide range of firing patterns. They normally fire constantly at a low rate, and speed up, firing a phasic burst when reward exceeds prediction, or pause when an expected reward does not occur. Therefore, the detection of bursts and pauses from spike train data is a critical problem when studying the role of phasic dopamine (DA) in reward related learning, and other DA dependent behaviors. However, few statistical methods have been developed that can identify bursts and pauses simultaneously. We propose a new statistical method, the Robust Gaussian Surprise (RGS) method, which performs an exhaustive search of bursts and pauses in spike trains simultaneously. We found that the RGS method is adaptable to various patterns of spike trains recorded in vivo, and is not influenced by baseline firing rate, making it applicable to all in vivo spike trains where baseline firing rates vary over time. We compare the performance of the RGS method to other methods of detecting bursts, such as the Poisson Surprise (PS), Rank Surprise (RS), and Template methods. Analysis of data using the RGS method reveals potential mechanisms underlying how bursts and pauses are controlled in DA neurons.

  8. Detecting fast radio bursts at decametric wavelengths

    Science.gov (United States)

    Rajwade, K. M.; Lorimer, D. R.

    2017-02-01

    Fast radio bursts (FRBs) are highly dispersed, sporadic radio pulses which are likely extragalactic in nature. Here, we investigate the constraints on the source population from surveys carried out at frequencies <1 GHz. All but one FRB has so far been discovered in the 1-2 GHz band, but new and emerging instruments look set to become valuable probes of the FRB population at sub-GHz frequencies in the near future. In this paper, we consider the impacts of free-free absorption and multipath scattering in our analysis via a number of different assumptions about the intervening medium. We consider previous low-frequency surveys along with an ongoing survey with University of Technology digital backend for the Molonglo Observatory Synthesis Telescope (UTMOST) as well as future observations with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX). We predict that CHIME and HIRAX will be able to observe ˜30 or more FRBs per day, even in the most extreme scenarios where free-free absorption and scattering can significantly impact the fluxes below 1 GHz. We also show that UTMOST will detect 1-2 FRBs per month of observations. For CHIME and HIRAX, the detection rates also depend greatly on the assumed FRB distance scale. Some of the models we investigated predict an increase in the FRB flux as a function of redshift at low frequencies. If FRBs are truly cosmological sources, this effect may impact future surveys in this band, particularly if the FRB population traces the cosmic star formation rate.

  9. Detecting Pipe Bursts Using Heuristic and CUSUM Methods

    NARCIS (Netherlands)

    Bakker, M.; Jung, D.; Vreeburg, J.; Van de 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 detecti

  10. Detection of GW bursts with chirplet-like template families

    Energy Technology Data Exchange (ETDEWEB)

    Chassande Mottin, Eric; Miele, Miriam [CNRS and Univ. Paris Denis Diderot, AstroParticule et Cosmologie (France); Mohapatra, Satya; Cadonati, Laura, E-mail: ecm@apc.univ-paris7.f [Physics Department, University of Massachusetts, Amherst MA 01003 (United States)

    2010-10-07

    Gravitational wave (GW) burst detection algorithms typically rely on the hypothesis that the burst signal is 'locally stationary', that is with slow variations of its frequency. Under this assumption, the signal can be decomposed into a small number of wavelets with constant frequency. This justifies the use of a family of sine-Gaussian wavelets in the Omega pipeline, one of the algorithms used in LIGO-Virgo burst searches. However, there are plausible scenarios where the burst frequency evolves rapidly, such as in the merger phase of a binary black-hole and/or neutron-star coalescence. In those cases, the local stationarity of sine Gaussians induces performance losses, due to the mismatch between the template and the actual signal. We propose an extension of the Omega pipeline based on chirplet-like templates. Chirplets incorporate an additional parameter, the chirp rate, to control the frequency variation. In this paper, we show that the Omega pipeline can easily be extended to include a chirplet template bank. We illustrate the method on a simulated data set, with a family of phenomenological binary black-hole coalescence waveforms embedded into Gaussian LIGO/Virgo-like noise. Chirplet-like templates result in an enhancement of the measured signal-to-noise ratio.

  11. Detection of bursts in neuronal spike trains by the mean inter-spike interval method

    Institute of Scientific and Technical Information of China (English)

    Lin Chen; Yong Deng; Weihua Luo; Zhen Wang; Shaoqun Zeng

    2009-01-01

    Bursts are electrical spikes firing with a high frequency, which are the most important property in synaptic plasticity and information processing in the central nervous system. However, bursts are difficult to identify because bursting activities or patterns vary with phys-iological conditions or external stimuli. In this paper, a simple method automatically to detect bursts in spike trains is described. This method auto-adaptively sets a parameter (mean inter-spike interval) according to intrinsic properties of the detected burst spike trains, without any arbitrary choices or any operator judgrnent. When the mean value of several successive inter-spike intervals is not larger than the parameter, a burst is identified. By this method, bursts can be automatically extracted from different bursting patterns of cultured neurons on multi-electrode arrays, as accurately as by visual inspection. Furthermore, significant changes of burst variables caused by electrical stimulus have been found in spontaneous activity of neuronal network. These suggest that the mean inter-spike interval method is robust for detecting changes in burst patterns and characteristics induced by environmental alterations.

  12. Time Resolved Spectroscopy of SGR J1550-5418 Bursts Detected with Fermi/Gamma-Ray Burst Monitor

    NARCIS (Netherlands)

    Younes, G.; Kouveliotou, C.; van der Horst, A.J.; Baring, M.G.; Granot, J.; Watts, A.L.; Bhat, P.N.; Collazzi, A.; Gehrels, N.; Gorgone, N.; Göğüş, E.; Gruber, D.; Grunblatt, S.; Huppenkothen, D.; Kaneko, Y.; von Kienlin, A.; van der Klis, M.; Lin, L.; Mcenery, J.; van Putten, T.; Wijers, R.A.M.J.

    2014-01-01

    We report on a time-resolved spectroscopy of the 63 brightest bursts of SGR J1550-5418, detected with the Fermi/Gamma-ray Burst Monitor during its 2008-2009 intense bursting episode. We performed spectral analysis down to 4 ms timescales to characterize the spectral evolution of the bursts. Using a

  13. BURST EVENT DETECTION IN WALL TURBULENCE BY WVITA METHOD

    Institute of Scientific and Technical Information of China (English)

    Jiang Nan; Shu Wei; Wang Zhendong

    2000-01-01

    Wavelet Variable Interval Time Average(WVITA)is introduced as a method incorporating burst event detection in wall turbulence.Wavelet transform is performed to unfold the longitudinal fluctuating velocity time series measured in the near wall region of a turbulent boundary layer using hot-film anemometer.This unfolding is both in time and in space simultaneously.The splitted kinetic of the longitudinal fluctuating velocity time series among different scales is obtained by integrating the square of wavelet coefficient modulus over temporal space.The time scale that related to burst events in wall turbulence passing through the fixed probe is ascertained by maximum criterion of the kinetic energy evolution across scales.Wavelet transformed localized variance of the fluctuating velocity time series at the maximum kinetic scale is put forward instead of localized short time average variance in Variable Interval Time Average(VITA)scheme.The burst event detection result shows that WVITA scheme can avoid erroneous judgement and solve the grouping problem more effectively which is caused by VITA scheme itself and can not be avoided by adjusting the threshold level or changing the short time average interval.

  14. Detection of burning ashes from thermonuclear X-ray bursts

    Science.gov (United States)

    Kajava, J. J. E.; Nättilä, J.; Poutanen, J.; Cumming, A.; Suleimanov, V.; Kuulkers, E.

    2017-01-01

    When neutron stars (NS) accrete gas from low-mass binary companions, explosive nuclear burning reactions in the NS envelope fuse hydrogen and helium into heavier elements. The resulting thermonuclear (type-I) X-ray bursts produce energy spectra that are fit well with black bodies, but a significant number of burst observations show deviations from Planck spectra. Here we present our analysis of RXTE/PCA observations of X-ray bursts from the NS low-mass X-ray binary HETE J1900.1-2455. We have discovered that the non-Planckian spectra are caused by photoionization edges. The anticorrelation between the strength of the edges and the colour temperature suggests that the edges are produced by the nuclear burning ashes that have been transported upwards by convection and become exposed at the photosphere. The atmosphere model fits show that occasionally the photosphere can consist entirely of metals, and that the peculiar changes in blackbody temperature and radius can be attributed to the emergence and disappearance of metals in the photosphere. As the metals are detected already in the Eddington-limited phase, it is possible that a radiatively driven wind ejects some of the burning ashes into the interstellar space.

  15. ESA's Integral detects closest cosmic gamma-ray burst

    Science.gov (United States)

    2004-08-01

    5 August 2004 A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, but also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed... Gamma ray burst model hi-res Size hi-res: 22 KB Credits: CXC/M. Weiss Artist impression of a low-energy gamma-ray burst This illustration describes a model for a gamma-ray burst, like the one detected by Integral on 3 December 2003 (GRB 031203). A jet of high-energy particles from a rapidly rotating black hole interacts with surrounding matter. Observations with Integral on 3 December 2003 and data on its afterglow, collected afterwards with XMM-Newton, Chandra and the Very Large Array telescope, show that GRB 031203 radiated only a fraction of the energy of normal gamma-ray bursts. Like supernovae, gamma-ray bursts are thought to be produced by the collapse of the core of a massive star. However, while the process leading to supernovae is relatively well understood, astronomers still do not know what happens when a core collapses to form a black hole. The discovery of 'under-energetic' gamma-ray bursts, like GRB 031203, should provide valuable clues as to links between supernovae, black holes and gamma-ray bursts. Lo-res JPG (22 Kb) Hi-res TIFF (5800 Kb) Cosmic gamma-ray bursts (GRBs) are flashes of gamma rays that can last from less than a second to a few minutes and occur at random positions in the sky. A large fraction of them is thought to result when a black hole is created from a dying star in a distant galaxy. Astronomers believe that a hot disc surrounding the black hole, made of gas and matter falling onto it, somehow emits an energetic beam parallel to the axis of rotation. According to the simplest picture, all GRBs

  16. Can Gravitons Be Detected?

    CERN Document Server

    Rothman, T; Boughn, Stephen; Rothman, Tony

    2006-01-01

    Freeman Dyson has questioned whether any conceivable experiment in the real universe can detect a single graviton. If not, is it meaningful to talk about gravitons as physical entities? We attempt to answer Dyson's question and find it is possible concoct an idealized thought experiment capable of detecting one graviton; however, when anything remotely resembling realistic physics is taken into account, detection becomes impossible, indicating that Dyson's conjecture is very likely true. We also point out several mistakes in the literature dealing with graviton detection and production.

  17. Detecting fast radio bursts at decametric wavelengths

    CERN Document Server

    Rajwade, Kaustubh

    2016-01-01

    Fast radio bursts (FRBs) are highly dispersed, sporadic radio pulses that are likely extragalactic in nature. Here we investigate the constraints on the source population from surveys carried out at frequencies $<1$~GHz. All but one FRB has so far been discovered in the 1--2~GHz band, but new and emerging instruments look set to become valuable probes of the FRB population at sub-GHz frequencies in the near future. In this paper, we consider the impacts of free-free absorption and multi-path scattering in our analysis via a number of different assumptions about the intervening medium. We consider previous low frequency surveys alongwith an ongoing survey with the University of Technology digital backend for the Molonglo Observatory Synthesis Telescope (UTMOST) as well as future observations with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and the Hydrogen Intensity and Real-Time Analysis Experiment (HIRAX). We predict that CHIME and HIRAX will be able to observe $\\sim$ 30 or more FRBs per da...

  18. RXTE detects X-ray bursts from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Soleri, P.; Watts, A.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.

    2010-01-01

    After the recent report of X-ray re-brightening (ATel #2608), RXTE has observed the peculiar neutron star X-ray binary Cir X-1 eleven times during the last two weeks (May 11-25, 2010). We report the detection of nine X-ray bursts in RXTE-PCA data, 25 years after the first -and the only previous- det

  19. Detection of burst suppression patterns in EEG using recurrence rate.

    Science.gov (United States)

    Liang, Zhenhu; Wang, Yinghua; Ren, Yongshao; Li, Duan; Voss, Logan; Sleigh, Jamie; Li, Xiaoli

    2014-01-01

    Burst suppression is a unique electroencephalogram (EEG) pattern commonly seen in cases of severely reduced brain activity such as overdose of general anesthesia. It is important to detect burst suppression reliably during the administration of anesthetic or sedative agents, especially for cerebral-protective treatments in various neurosurgical diseases. This study investigates recurrent plot (RP) analysis for the detection of the burst suppression pattern (BSP) in EEG. The RP analysis is applied to EEG data containing BSPs collected from 14 patients. Firstly we obtain the best selection of parameters for RP analysis. Then, the recurrence rate (RR), determinism (DET), and entropy (ENTR) are calculated. Then RR was selected as the best BSP index one-way analysis of variance (ANOVA) and multiple comparison tests. Finally, the performance of RR analysis is compared with spectral analysis, bispectral analysis, approximate entropy, and the nonlinear energy operator (NLEO). ANOVA and multiple comparison tests showed that the RR could detect BSP and that it was superior to other measures with the highest sensitivity of suppression detection (96.49%, P = 0.03). Tracking BSP patterns is essential for clinical monitoring in critically ill and anesthetized patients. The purposed RR may provide an effective burst suppression detector for developing new patient monitoring systems.

  20. Detection of Burst Suppression Patterns in EEG Using Recurrence Rate

    Directory of Open Access Journals (Sweden)

    Zhenhu Liang

    2014-01-01

    Full Text Available Burst suppression is a unique electroencephalogram (EEG pattern commonly seen in cases of severely reduced brain activity such as overdose of general anesthesia. It is important to detect burst suppression reliably during the administration of anesthetic or sedative agents, especially for cerebral-protective treatments in various neurosurgical diseases. This study investigates recurrent plot (RP analysis for the detection of the burst suppression pattern (BSP in EEG. The RP analysis is applied to EEG data containing BSPs collected from 14 patients. Firstly we obtain the best selection of parameters for RP analysis. Then, the recurrence rate (RR, determinism (DET, and entropy (ENTR are calculated. Then RR was selected as the best BSP index one-way analysis of variance (ANOVA and multiple comparison tests. Finally, the performance of RR analysis is compared with spectral analysis, bispectral analysis, approximate entropy, and the nonlinear energy operator (NLEO. ANOVA and multiple comparison tests showed that the RR could detect BSP and that it was superior to other measures with the highest sensitivity of suppression detection (96.49%,  P=0.03. Tracking BSP patterns is essential for clinical monitoring in critically ill and anesthetized patients. The purposed RR may provide an effective burst suppression detector for developing new patient monitoring systems.

  1. VERITAS OBSERVATIONS OF GAMMA-RAY BURSTS DETECTED BY SWIFT

    Energy Technology Data Exchange (ETDEWEB)

    Acciari, V. A.; Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Aliu, E.; Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Bradbury, S. M. [School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT (United Kingdom); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Christiansen, J. L. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 94307 (United States); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Duke, C. [Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); and others

    2011-12-10

    We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t{sup -1.5} time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope on board the Fermi satellite. No significant very high energy (VHE) gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light and interpreted in the context of the keV emission detected by Swift. For some bursts the VHE emission must have less power than the keV emission, placing constraints on inverse Compton models of VHE emission.

  2. ESA's X-ray space telescope proves supernovae can cause mysterious gamma-ray bursts

    Science.gov (United States)

    2002-04-01

    By analysing the afterglow of the gamma-ray burst in the X-ray light, scientists produced the first ever evidence of the presence of chemical elements which were the unmistakable remnants of a supernova explosion which had occurred just a few days before. "We can now confidently say that the death of a massive star, a supernova, was the cause of a gamma-ray burst. However we still don't know exactly how and why these bursts, the most energetic phenomena in the Universe, are triggered," says ESA astronomer Norbert Schartel, a co-author of the original paper, published today in Nature. Gamma-ray bursts were first discovered in 1967 by chance, when satellites designed to look for violations of the Nuclear Test Ban Treaty detected strong gamma-ray emissions coming from sources not in the vicinity of Earth, but from outer space. They have been a mystery ever since. They occur as often as several times a day but last for no longer than a couple of minutes, and there is no way to predict when or where the next burst will occur. Consequently they are very difficult to study. For three decades it was not even known whether the explosions were close, in our own Milky Way galaxy, or far away in distant galaxies. But astronomers set up an 'alert system'. This allows them to see the 'afterglow' of the burst before it fades away, by quickly aiming their telescopes at the precise location in the sky shortly after a detector triggers the alert. It is now clear that the bursts occur in galaxies millions of light-years away. The longest burst Technically called 'GRB 011211', it was first detected on 11 December 2001 at 19:09:21 (Universal Time), by the Italian-Dutch satellite BeppoSAX. The burst lasted for 270 seconds - the longest one observed by the satellite. A few hours afterwards, when a first analysis confirmed that a burst had indeed been registered, the BeppoSAX team alerted the rest of the astronomical community. ESA's XMM-Newton arrived on the scene 11 hours after the

  3. Optimal detection of burst events in gravitational wave interferometric observatories

    CERN Document Server

    Viceré, A

    2002-01-01

    We consider the problem of detecting a burst signal of unknown shape. We introduce a statistic which generalizes the excess power statistic proposed by Flanagan and Hughes and extended by Anderson et al. The statistic we propose is shown to be optimal for arbitrary noise spectral characteristic, under the two hypotheses that the noise is Gaussian, and that the prior for the signal is uniform. The statistic derivation is based on the assumption that a signal affects only affects N samples in the data stream, but that no other information is a priori available, and that the value of the signal at each sample can be arbitrary. We show that the proposed statistic can be implemented combining standard time-series analysis tools which can be efficiently implemented, and the resulting computational cost is still compatible with an on-line analysis of interferometric data. We generalize this version of an excess power statistic to the multiple detector case, also including the effect of correlated noise. We give full...

  4. A comparison of computational methods for detecting bursts in neuronal spike trains and their application to human stem cell-derived neuronal networks.

    Science.gov (United States)

    Cotterill, Ellese; Charlesworth, Paul; Thomas, Christopher W; Paulsen, Ole; Eglen, Stephen J

    2016-08-01

    Accurate identification of bursting activity is an essential element in the characterization of neuronal network activity. Despite this, no one technique for identifying bursts in spike trains has been widely adopted. Instead, many methods have been developed for the analysis of bursting activity, often on an ad hoc basis. Here we provide an unbiased assessment of the effectiveness of eight of these methods at detecting bursts in a range of spike trains. We suggest a list of features that an ideal burst detection technique should possess and use synthetic data to assess each method in regard to these properties. We further employ each of the methods to reanalyze microelectrode array (MEA) recordings from mouse retinal ganglion cells and examine their coherence with bursts detected by a human observer. We show that several common burst detection techniques perform poorly at analyzing spike trains with a variety of properties. We identify four promising burst detection techniques, which are then applied to MEA recordings of networks of human induced pluripotent stem cell-derived neurons and used to describe the ontogeny of bursting activity in these networks over several months of development. We conclude that no current method can provide "perfect" burst detection results across a range of spike trains; however, two burst detection techniques, the MaxInterval and logISI methods, outperform compared with others. We provide recommendations for the robust analysis of bursting activity in experimental recordings using current techniques.

  5. VERITAS Observations of Gamma-Ray Bursts Detected by Swift

    CERN Document Server

    Acciari, V A; Arlen, T; Aune, T; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Byrum, K; Cannon, A; Cesarini, A; Christiansen, J L; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Duke, C; Errando, M; Falcone, A; Finley, J P; Finnegan, G; Fortson, L; Furniss, A; Galante, N; Gall, D; Godambe, S; Griffin, S; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Hughes, G; Hui, C M; Humensky, T B; Jackson, D J; Kaaret, P; Karlsson, N; Kertzman, M; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Madhavan, A S; Maier, G; McArthur, S; McCann, A; Moriarty, P; Newbold, M D; Ong, R A; Orr, M; Otte, A N; Park, N; Perkins, J S; Pohl, M; Prokoph, H; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Ruppel, J; Saxon, D B; Schroedter, M; Sembroski, G H; Şentürk, G D; Smith, A W; Staszak, D; Swordy, S P; Tešić, G; Theiling, M; Thibadeau, S; Tsurusaki, K; Varlotta, A; Vassiliev, V V; Vincent, S; Vivier, M; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Weisgarber, T; Williams, D A; Wood, M

    2011-01-01

    We present the results of sixteen Swift-triggered GRB follow-up observations taken with the VERITAS telescope array from January, 2007 to June, 2009. The median energy threshold and response time of these observations was 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter time scale determined by the maximum VERITAS sensitivity to a burst with a t^-1.5 time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope (LAT) on-board the Fermi satellite. No significant VHE gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light (EBL) and interpreted in the context of the keV emission detected by Swift. For some bursts the VH...

  6. An information-theoretic approach to the gravitational-wave burst detection problem

    Science.gov (United States)

    Katsavounidis, E.; Lynch, R.; Vitale, S.; Essick, R.; Robinet, F.

    2016-03-01

    The advanced era of gravitational-wave astronomy, with data collected in part by the LIGO gravitational-wave interferometers, has begun as of fall 2015. One potential type of detectable gravitational waves is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a new detection algorithm - called oLIB - that can be used in relatively low-latency to turn calibrated strain data into a detection significance statement. This pipeline consists of 1) a sine-Gaussian matched-filter trigger generator based on the Q-transform - known as Omicron -, 2) incoherent down-selection of these triggers to the most signal-like set, and 3) a fully coherent analysis of this signal-like set using the Markov chain Monte Carlo (MCMC) Bayesian evidence calculator LALInferenceBurst (LIB). We optimally extract this information by using a likelihood-ratio test (LRT) to map these search statistics into a significance statement. Using representative archival LIGO data, we show that the algorithm can detect gravitational-wave burst events of realistic strength in realistic instrumental noise with good detection efficiencies across different burst waveform morphologies. With support from the National Science Foundation under Grant PHY-0757058.

  7. Analysis of historic bursts and burst detection in water supply areas of different size

    NARCIS (Netherlands)

    Bakker, M.; Trietsch, E.A.; Vreeburg, J.H.G.; Rietveld, L.C.

    2014-01-01

    Pipe bursts in water distribution networks lead to water losses and a risk of damaging the urban environment. We studied hydraulic data and customer contact records of 44 real bursts for a better understanding of the phenomena. We found that most bursts were reported to the water company shortly aft

  8. What Can Be Interesting in the Analysis of Crowded Solar Bursts?

    Science.gov (United States)

    Stanislavsky, A. A.; Konovalenko, A. A.; Koval, A. A.; Dorovsky, V. V.; Zarka, Ph.; Rucker, H. O.

    2015-03-01

    At decameter wavelengths the radio astronomy observations reveal a wide variety of solar bursts. They are associated with solar activity manifestations such as movements of electron beams and shock waves in solar corona, flare- related events, coronal mass ejections and others. The analysis of burst features allows one to use them as probing signals which comprise useful information about solar corona parameters and their changes over time. By frequency-time measurements of different types of solar bursts occurred about the same time one can provide a comparative study of their properties, complementing the missing pieces in the complex mosaic of solar events. In this purpose we discuss features of their signal processing by the gradient filtration, as applied to quasi-periodic bursts like a zebra pattern related to Bernstein modes. The measured frequency periodicity of the bursts gives a chance to determine the magnetic field strength in upper corona around the protracted solar minimum of solar activity.

  9. Adaptive Kalman Filter Based on Adjustable Sampling Interval in Burst Detection for Water Distribution System

    Directory of Open Access Journals (Sweden)

    Doo Yong Choi

    2016-04-01

    Full Text Available Rapid detection of bursts and leaks in water distribution systems (WDSs can reduce the social and economic costs incurred through direct loss of water into the ground, additional energy demand for water supply, and service interruptions. Many real-time burst detection models have been developed in accordance with the use of supervisory control and data acquisition (SCADA systems and the establishment of district meter areas (DMAs. Nonetheless, no consideration has been given to how frequently a flow meter measures and transmits data for predicting breaks and leaks in pipes. This paper analyzes the effect of sampling interval when an adaptive Kalman filter is used for detecting bursts in a WDS. A new sampling algorithm is presented that adjusts the sampling interval depending on the normalized residuals of flow after filtering. The proposed algorithm is applied to a virtual sinusoidal flow curve and real DMA flow data obtained from Jeongeup city in South Korea. The simulation results prove that the self-adjusting algorithm for determining the sampling interval is efficient and maintains reasonable accuracy in burst detection. The proposed sampling method has a significant potential for water utilities to build and operate real-time DMA monitoring systems combined with smart customer metering systems.

  10. Detection of burning ashes from thermonuclear X-ray bursts

    CERN Document Server

    Kajava, J J E; Poutanen, J; Cumming, A; Suleimanov, V; Kuulkers, E

    2016-01-01

    When neutron stars (NS) accrete gas from low-mass binary companions, explosive nuclear burning reactions in the NS envelope fuse hydrogen and helium into heavier elements. The resulting thermonuclear (type-I) X-ray bursts produce energy spectra that are fit well with black bodies, but a significant number of burst observations show deviations from Planck spectra. Here we present our analysis of RXTE/PCA observations of X-ray bursts from the NS low-mass X-ray binary HETE J1900.1-2455. We have discovered that the non-Planckian spectra are caused by photo-ionization edges. The anti-correlation between the strength of the edges and the colour temperature suggests that the edges are produced by the nuclear burning ashes that have been transported upwards by convection and become exposed at the photosphere. The atmosphere model fits show that occasionally the photosphere can consist entirely of metals, and that the peculiar changes in black body temperature and radius can be attributed to the emergence and disappea...

  11. SGR J1550-5418 bursts detected with the Fermi Gamma-ray Burst Monitor during its most prolific activity

    CERN Document Server

    van der Horst, A J; 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; Connaughton, V; Finger, M H; Gehrels, N; Gibby, M H; Giles, M M; Goldstein, A; Gruber, D; Harding, A K; Kaper, L; von Kienlin, A; van der Klis, M; McBreen, S; Mcenery, J; Meegan, C A; Paciesas, W S; Pe'er, A; Preece, R D; Ramirez-Ruiz, E; Rau, A; Wachter, S; Wilson-Hodge, C; Woods, P M; Wijers, R A M J

    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 January 2009, 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 with an exponential cutoff (Comptonized model), and two black-body functions (BB+BB). In the spectral fits with the Comptonized model we find a mean power-law index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlati...

  12. Burst detection in turbulent channel flows based on large eddy simulation databases

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Qiang; ZHOU; Jifu; LI; Jiachun

    2005-01-01

    Reliable turbulent channel flow databases at several Reynolds numbers have been established by large eddy simulation (LES), with two of them validated by comparing with typical direct numerical simulation (DNS) results. Furthermore, the statistics, such as velocity profile, turbulent intensities and shear stress, were obtained as well as the temporal and spatial structure of turbulent bursts. Based on the LES databases available, the conditional sampling methods are used to detect the structures of burst events. A method to deterimine the grouping parameter from the probability distribution function (pdf) curve of the time separation between ejection events is proposed to avoid the errors in detected results. And thus, the dependence of average burst period on thresholds is considerably weakened. Meanwhile, the average burst-to- bed area ratios are detected. It is found that the Reynolds number exhibits little effect on the burst period and burst-to-bed area ratio

  13. A behavioral role for feature detection by sensory bursts.

    Science.gov (United States)

    Marsat, Gary; Pollack, Gerald S

    2006-10-11

    Brief episodes of high-frequency firing of sensory neurons, or bursts, occur in many systems, including mammalian auditory and visual systems, and are believed to signal the occurrence of particularly important stimulus features, i.e., to function as feature detectors. However, the behavioral relevance of sensory bursts has not been established in any system. Here, we show that bursts in an identified auditory interneuron of crickets reliably signal salient stimulus features and reliably predict behavioral responses. Our results thus demonstrate the close link between sensory bursts and behavior.

  14. Detection of tremor bursts by a running second order moment function and analysis using interburst histograms

    NARCIS (Netherlands)

    Journee, Henricus Louis; Postma, Alida Annechien; Sun, Mingui; Staal, Michiel J.

    2008-01-01

    Introduction: Conventional linear signal processing techniques are not always suitable for the detection of tremor bursts in clinical practice due to inevitable noise from electromyographic (EMG) bursts. This study introduces (1) a non-linear analysis technique based on a running second order moment

  15. Swift-XRT detects X-ray burst from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Soleri, P.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Watts, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.; Chakrabarty, D.; Homan, J.

    2010-01-01

    Following the recent re-brightening (ATel #2608) and RXTE-PCA detection of X-ray bursts from the peculiar X-ray binary Cir X-1 between May 15 and 25 (ATel #2643), we obtained a series of Swift-XRT observations of the field (see also ATel #2650). Swift-XRT detected an X-ray burst on 2010-05-28 at 12:

  16. An information-theoretic approach to the gravitational-wave burst detection problem

    CERN Document Server

    Lynch, Ryan; Essick, Reed; Katsavounidis, Erik; Robinet, Florent

    2015-01-01

    The advanced era of gravitational-wave astronomy, with data collected in part by the LIGO gravitational-wave interferometers, has begun as of fall 2015. One potential type of detectable gravitational waves is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a new detection algorithm -- called \\textit{oLIB} -- that can be used in relatively low-latency to turn calibrated strain data into a detection significance statement. This pipeline consists of 1) a sine-Gaussian matched-filter trigger generator based on the Q-transform -- known as \\textit{Omicron} --, 2) incoherent down-selection of these triggers to the most signal-like set, and 3) a fully coherent analysis of this signal-like set using the Markov chain Monte Carlo (MCMC) Bayesian evidence calculator \\textit{LALInferenceBurst} (LIB). These steps effectively compress the full data stream into a set of search statistics for the most signal-like events, and we use elements from information t...

  17. Can Lies Be Detected Unconsciously?

    Directory of Open Access Journals (Sweden)

    David eShanks

    2015-08-01

    Full Text Available People are typically poor at telling apart truthful and deceptive statements. Based on the Unconscious Thought Theory, it has been suggested that poor lie detection arises from the intrinsic limitations of conscious thinking and can be improved by facilitating the contribution of unconscious thought. In support of this hypothesis, Reinhard, Greifeneder, and Scharmach (2013 observed improved lie detection among participants engaging in unconscious thought. The present study aimed to replicate this unconscious thought advantage using a similar experimental procedure but with an important improvement in a key control condition. Specifically, participants judged the truthfulness of 8 video recordings in three thinking modes: immediately after watching them or after a period of unconscious or conscious deliberation. Results from two experiments (combined N = 226 failed to reveal a significant difference in lie detection accuracy between the thinking modes, even after efforts were made to facilitate the occurrence of an unconscious thought advantage in Experiment 2. The results imply that the unconscious thought advantage in deception detection is not a robust phenomenon.

  18. Bursting thalamic responses in awake monkey contribute to visual detection and are modulated by corticofugal feedback.

    Science.gov (United States)

    Ortuño, Tania; Grieve, Kenneth L; Cao, Ricardo; Cudeiro, Javier; Rivadulla, Casto

    2014-01-01

    The lateral geniculate nucleus is the gateway for visual information en route to the visual cortex. Neural activity is characterized by the existence of two firing modes: burst and tonic. Originally associated with sleep, bursts have now been postulated to be a part of the normal visual response, structured to increase the probability of cortical activation, able to act as a "wake-up" call to the cortex. We investigated a potential role for burst in the detection of novel stimuli by recording neuronal activity in the lateral geniculate nucleus (LGN) of behaving monkeys during a visual detection task. Our results show that bursts are often the neuron's first response, and are more numerous in the response to attended target stimuli than to unattended distractor stimuli. Bursts are indicators of the task novelty, as repetition decreased bursting. Because the primary visual cortex is the major modulatory input to the LGN, we compared the results obtained in control conditions with those observed when cortical activity was reduced by TMS. This cortical deactivation reduced visual response related bursting by 90%. These results highlight a novel role for the thalamus, able to code higher order image attributes as important as novelty early in the thalamo-cortical conversation.

  19. Bursting thalamic responses in awake monkey contribute to visual detection and are modulated by corticofugal feedback

    Directory of Open Access Journals (Sweden)

    Tania eOrtuno

    2014-05-01

    Full Text Available The lateral geniculate nucleus is the gateway for visual information en route to the visual cortex. Neural activity is characterized by the existence of 2 firing modes: burst and tonic. Originally associated with sleep, bursts have now been postulated to be a part of the normal visual response, structured to increase the probability of cortical activation, able to act as a wake-up call to the cortex. We investigated a potential role for burst in the detection of novel stimuli by recording neuronal activity in the LGN of behaving monkeys during a visual detection task. Our results show that bursts are often the neuron’s first response, and are more numerous in the response to attended target stimuli than to unattended distractor stimuli. Bursts are indicators of the task novelty, as repetition decreased bursting. Because the primary visual cortex is the major modulatory input to the LGN, we compared the results obtained in control conditions with those observed when cortical activity was reduced by TMS. This cortical deactivation reduced visual response related bursting by 90%. These results highlight a novel role for the thalamus, able to code higher order image attributes as important as novelty early in the thalamo-cortical conversation.

  20. Periodic Lateralized Epileptiform Discharges can Survive Anesthesia and Result in Asymmetric Drug-induced Burst Suppression

    Science.gov (United States)

    Mader, Edward C.; Cannizzaro, Louis A.; Williams, Frank J.; Lalan, Saurabh; Olejniczak, Piotr W.

    2017-01-01

    Drug-induced burst suppression (DIBS) is bihemispheric and bisymmetric in adults and older children. However, asymmetric DIBS may occur if a pathological process is affecting one hemisphere only or both hemispheres disproportionately. The usual suspect is a destructive lesion; an irritative or epileptogenic lesion is usually not invoked to explain DIBS asymmetry. We report the case of a 66-year-old woman with new-onset seizures who was found to have a hemorrhagic cavernoma and periodic lateralized epileptiform discharges (PLEDs) in the right temporal region. After levetiracetam and before anesthetic antiepileptic drugs (AEDs) were administered, the electroencephalogram (EEG) showed continuous PLEDs over the right hemisphere with maximum voltage in the posterior temporal region. Focal electrographic seizures also occurred occasionally in the same location. Propofol resulted in bihemispheric, but not in bisymmetric, DIBS. Remnants or fragments of PLEDs that survived anesthesia increased the amplitude and complexity of the bursts in the right hemisphere leading to asymmetric DIBS. Phenytoin, lacosamide, ketamine, midazolam, and topiramate were administered at various times in the course of EEG monitoring, resulting in suppression of seizures but not of PLEDs. Ketamine and midazolam reduced the rate, amplitude, and complexity of PLEDs but only after producing substantial attenuation of all burst components. When all anesthetics were discontinued, the EEG reverted to the original preanesthesia pattern with continuous non-fragmented PLEDs. The fact that PLEDs can survive anesthesia and affect DIBS symmetry is a testament to the robustness of the neurodynamic processes underlying PLEDs. PMID:28286626

  1. Time resolved spectroscopy of SGR J1550–5418 bursts detected with Fermi/gamma-ray burst monitor

    Energy Technology Data Exchange (ETDEWEB)

    Younes, G. [Universities Space Research Association, 6767 Old Madison Pike, Suite 450, Huntsville, AL 35806 (United States); Kouveliotou, C.; Collazzi, A. [Astrophysics Office, ZP 12, NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, A. J.; Watts, A. L.; Huppenkothen, D.; Van der Klis, M.; Van Putten, T. [Astronomical Institute " Anton Pannekoek," University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Raánana 43537 (Israel); Bhat, P. N.; Gorgone, N. [University of Alabama in Huntsville CSPAR, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, N.; Mcenery, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Göğüş, E.; Kaneko, Y.; Lin, L. [Sabancı University, Orhanlı-Tuzla, İstanbul 34956 (Turkey); Gruber, D.; Von Kienlin, A. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, D-85748 Garching (Germany); Grunblatt, S. [University of Hawaii at Manoa, 2500 Campus Road, Honolulu, HI 96822 (United States); and others

    2014-04-10

    We report on a time-resolved spectroscopy of the 63 brightest bursts of SGR J1550–5418, detected with the Fermi/Gamma-ray Burst Monitor during its 2008-2009 intense bursting episode. We performed spectral analysis down to 4 ms timescales to characterize the spectral evolution of the bursts. Using a Comptonized model, we find that the peak energy, E {sub peak}, anti-correlates with flux, while the low-energy photon index remains constant at ∼ – 0.8 up to a flux limit F ≈ 10{sup –5} erg s{sup –1} cm{sup –2}. Above this flux value, the E {sub peak}–flux correlation changes sign, and the index positively correlates with the flux reaching ∼1 at the highest fluxes. Using a two blackbody model, we find that the areas and fluxes of the two emitting regions correlate positively. Further, we study here for the first time the evolution of the temperatures and areas as a function of flux. We find that the area–kT relation follows the lines of constant luminosity at the lowest fluxes, R {sup 2}∝kT {sup –4}, with a break at the higher fluxes (F > 10{sup –5.5} erg s{sup –1} cm{sup –2}). The area of the high-kT component increases with the flux while its temperature decreases, which we interpret as being due to an adiabatic cooling process. The area of the low-kT component, on the other hand, appears to saturate at the highest fluxes, toward R {sub max} ≈ 30 km. Assuming that crust quakes are responsible for soft gamma repeater (SGR) bursts and considering R {sub max} as the maximum radius of the emitting photon-pair plasma fireball, we relate this saturation radius to a minimum excitation radius of the magnetosphere, and we put a lower limit on the internal magnetic field of SGR J1550–5418, B {sub int} ≳ 4.5 × 10{sup 15} G.

  2. A Machine Learning Classifier for Fast Radio Burst Detection at the VLBA

    CERN Document Server

    Wagstaff, Kiri L; Thompson, David R; Khudikyan, Shakeh; Wyngaard, Jane; Deller, Adam T; Palaniswamy, Divya; Tingay, Steven J; Wayth, Randall B

    2016-01-01

    Time domain radio astronomy observing campaigns frequently generate large volumes of data. Our goal is to develop automated methods that can identify events of interest buried within the larger data stream. The V-FASTR fast transient system was designed to detect rare fast radio bursts (FRBs) within data collected by the Very Long Baseline Array. The resulting event candidates constitute a significant burden in terms of subsequent human reviewing time. We have trained and deployed a machine learning classifier that marks each candidate detection as a pulse from a known pulsar, an artifact due to radio frequency interference, or a potential new discovery. The classifier maintains high reliability by restricting its predictions to those with at least 90% confidence. We have also implemented several efficiency and usability improvements to the V-FASTR web-based candidate review system. Overall, we found that time spent reviewing decreased and the fraction of interesting candidates increased. The classifier now c...

  3. Astronomers Detect Powerful Bursting Radio Source Discovery Points to New Class of Astronomical Objects

    Science.gov (United States)

    2005-03-01

    transients has been very exciting for our students,” Hyman added. Participating in this research program has inspired at least two of Hyman?s students — Jennifer Neureuther and Mariana Lazarova — to pursue graduate studies in astronomy. This project was supported at Sweet Briar College by funding from Research Corporation and the Jeffress Foundation. Basic research in radio astronomy at NRL is supported by the Office of Naval Research. Further Research Hyman and his NRL colleagues plan to continue monitoring the Galactic center and search for the source again with the VLA and other X-ray and radio telescopes. They are also developing (with Dr. Kent Wood of NRL) a model that attempts to account for the radio bursts as a new type of outburst from a class of sources known as “magnetars.” NRL is also contributing to an effort to build the world’s largest and most sensitive low-frequency telescope, called the Long Wavelength Array (LWA), which may revolutionize future searches for other radio transient sources. Current plans call for the LWA, which is being developed by the University of New Mexico-led Southwest Consortium, to be sited in New Mexico, not far from the VLA. “One of the key advantages of observing at long radio wavelengths,” explained NRL astronomer, Dr. Namir Kassim, “is that the field-of-view is so large that a single observation can efficiently detect transient phenomena over a large region.” “When completed, the LWA may uncover hundreds of previously unknown radio transients, some of which may be examples of Jupiter-like planets orbiting other stars,” Kassim added. Jupiter is the most famous example of a nearby radio transient. About Sweet Briar College Sweet Briar College is consistently ranked among the nation’s top liberal arts colleges.ÿ Founded in 1901 as an independent undergraduate college for women, Sweet Briar continues its commitment to the education of women, offering a full range of liberal arts majors, including subjects

  4. SROSS C-2 Detections of Gamma Ray Bursts and the SGR 1627-41

    Indian Academy of Sciences (India)

    S. Sinha; P. Sreekumar; K. Kasturirangan

    2002-03-01

    The GRB monitor (GRBM) on board the Indian SROSS C-2 satellite has detected 53 classical gamma ray bursts since its launch in May, 1994 till its re-entry in July, 2001. For a subset of 26 events, locations were obtained from simultaneous observations by other gamma-ray detectors in space. The sky distribution of these 26 SROSS C-2 bursts is consistent with isotropy. The distribution of event durations shows evidence for bimodality. There is an evidence for a moderate hardness ratio-intensity (HIC) correlation in the data. The SROSS C-2 GRBM has also detected three episodes of emission from the SGR 1627-41.

  5. Possible Gamma-Ray Burst radio detections by the Square Kilometre Array. New perspectives

    CERN Document Server

    Ruggeri, Alan Cosimo

    2016-01-01

    The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several months. This approach would be extremely useful to extend the Spectrum Energetic Distribution (SED) from the gamma to the to radio band and would increase the number of radio detectable GRBs. In principle, the SKA could help to understand the physics of GRBs by setting constraints on theoretical models. This goal could be achieved by taking into account multiple observations at different wavelengths in order to obtain a deeper insight of the sources. Here, we present an estimation of GRB radio detections, showing that the GRBs can really be observed by the SKA. The approach that we present consists in determining blind detection rates derived by a very large sample con...

  6. CAN BLACK HOLE NEUTRINO-COOLED DISKS POWER SHORT GAMMA-RAY BURSTS?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tong; Gu, Wei-Min [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China); Lin, Yi-Qing [School of Opto-electronic and Communication Engineering, Xiamen University of Technology, Xiamen, Fujian 361024 (China); Hou, Shu-Jin, E-mail: tongliu@xmu.edu.cn [Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China)

    2015-06-10

    Stellar-mass black holes (BHs) surrounded by neutrino-dominated accretion flows (NDAFs) are plausible sources of power for gamma-ray bursts (GRBs) via neutrino emission and their annihilation. The progenitors of short-duration GRBs (SGRBs) are generally considered to be compact binary mergers. According to the simulation results, the disk mass of the NDAF is limited after merger events. We can estimate such disk masses using the current SGRB observational data and fireball model. The results show that the disk mass of a certain SGRB mainly depends on its output energy, jet opening angle, and central BH characteristics. Even for the extreme BH parameters, some SGRBs require massive disks, which approach or exceed the limits in simulations. We suggest that there may exist alternative MHD processes or mechanisms that increase the neutrino emission to produce SGRBs with reasonable BH parameters and disk masses.

  7. Can black-hole neutrino-cooled disks power short gamma-ray bursts?

    CERN Document Server

    Liu, Tong; Hou, Shu-Jin; Gu, Wei-Min

    2015-01-01

    Stellar-mass black holes (BHs) surrounded by neutrino-dominated accretion flows (NDAFs) are the plausible candidates to power gamma-ray bursts (GRBs) via neutrinos emission and their annihilation. The progenitors of short-duration GRBs (SGRBs) are generally considered to be compact binaries mergers. According to the simulation results, the disk mass of the NDAF has been limited after merger events. We can estimate such disk mass by using the current SGRB observational data and fireball model. The results show that the disk mass of a certain SGRB mainly depends on its output energy, jet opening angle, and central BH characteristics. Even for the extreme BH parameters, some SGRBs require massive disks, which approach or exceed the limits in simulations. We suggest that there may exist alternative magnetohydrodynamic processes or some mechanisms increasing the neutrino emission to produce SGRBs with the reasonable BH parameters and disk mass.

  8. Enabling high confidence detections of gravitational-wave bursts

    CERN Document Server

    Littenberg, Tyson B; Cornish, Neil J; Millhouse, Margaret

    2015-01-01

    With the advanced LIGO and Virgo detectors taking observations the detection of gravitational waves is expected within the next few years. Extracting astrophysical information from gravitational wave detections is a well-posed problem and thoroughly studied when detailed models for the waveforms are available. However, one motivation for the field of gravitational wave astronomy is the potential for new discoveries. Recognizing and characterizing unanticipated signals requires data analysis techniques which do not depend on theoretical predictions for the gravitational waveform. Past searches for short-duration un-modeled gravitational wave signals have been hampered by transient noise artifacts, or "glitches," in the detectors. In some cases, even high signal-to-noise simulated astrophysical signals have proven difficult to distinguish from glitches, so that essentially any plausible signal could be detected with at most 2-3 $\\sigma$ level confidence. We have put forth the BayesWave algorithm to differentiat...

  9. Possible gamma-ray burst radio detections by the Square Kilometre Array. New perspectives

    Science.gov (United States)

    Ruggeri, Alan Cosimo; Capozziello, Salvatore

    2016-09-01

    The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several months. This approach would be extremely useful to extend the Spectrum Energetic Distribution (SED) from the gamma to the to radio band and would increase the number of radio detectable GRBs. In principle, the SKA could help to understand the physics of GRBs by setting constraints on theoretical models. This goal could be achieved by taking into account multiple observations at different wavelengths in order to obtain a deeper insight of the sources. Here, we present an estimation of GRB radio detections, showing that the GRBs can really be observed by the SKA. The approach that we present consists in determining blind detection rates derived by a very large sample consisting of merging several GRB catalogues observed by current missions as Swift, Fermi, Agile and INTEGRAL and by previous missions as BeppoSAX, CGRO, GRANAT, HETE-2, Ulysses and Wind. The final catalogue counts 7516 distinct sources. We compute the fraction of GRBs that could be observed by the SKA at high and low frequencies, above its observable sky. Considering the planned SKA sensitivity and through an extrapolation based on previous works and observations, we deduce the minimum fluence in the range 15-150 keV. This is the energy interval where a GRB should emit to be detectable in the radio band by the SKA. Results seem consistent with observational capabilities.

  10. Spectral catalogue of bright gamma-ray bursts detected with the BeppoSAX/GRBM

    Science.gov (United States)

    Guidorzi, C.; Lacapra, M.; Frontera, F.; Montanari, E.; Amati, L.; Calura, F.; Nicastro, L.; Orlandini, M.

    2011-02-01

    Context. The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues derived from past and present experiments are known in the literature and allow to tackle the issue of spectral properties of gamma-ray bursts on a statistical ground. Aims: We extracted and studied the time-integrated photon spectra of the 200 brightest GRBs observed with the Gamma-Ray Burst Monitor which flew aboard the BeppoSAX mission (1996-2002) to provide an independent statistical characterisation of GRB spectra. Methods: The spectra have a time-resolution of 128 s and consist of 240 energy channels covering the 40-700 keV energy band. The 200 brightest GRBs were selected from the complete catalogue of 1082 GRBs detected with the GRBM (Frontera et al. 2009), whose products are publicly available and can be browsed/retrieved using a dedicated web interface. The spectra were fit with three models: a simple power law, a cut-off power law or a Band model. We derived the sample distributions of the best-fitting spectral parameters and investigated possible correlations between them. For a few, typically very long GRBs, we also provide a loose (128-s) time-resolved spectroscopic analysis. Results: The typical photon spectrum of a bright GRB consists of a low-energy index around 1.0 and a peak energy of the ν F_ν spectrum Ep ≃ 240 keV in agreement with previous results on a sample of bright CGRO/BATSE bursts. Spectra of ~ 35% of GRBs can be fit with a power law with a photon index around 2, indicative of peak energies either close to or outside the GRBM energy boundaries. We confirm the correlation between Ep and fluence, in agreement with previous results, with a logarithmic dispersion of 0.13 around the power law with index 0.21 ± 0.06. This is shallower than its analogous in the GRB rest-frame, the Amati relation

  11. A Machine Learning Classifier for Fast Radio Burst Detection at the VLBA

    Science.gov (United States)

    Wagstaff, Kiri L.; Tang, Benyang; Thompson, David R.; Khudikyan, Shakeh; Wyngaard, Jane; Deller, Adam T.; Palaniswamy, Divya; Tingay, Steven J.; Wayth, Randall B.

    2016-08-01

    Time domain radio astronomy observing campaigns frequently generate large volumes of data. Our goal is to develop automated methods that can identify events of interest buried within the larger data stream. The V-FASTR fast transient system was designed to detect rare fast radio bursts within data collected by the Very Long Baseline Array. The resulting event candidates constitute a significant burden in terms of subsequent human reviewing time. We have trained and deployed a machine learning classifier that marks each candidate detection as a pulse from a known pulsar, an artifact due to radio frequency interference, or a potential new discovery. The classifier maintains high reliability by restricting its predictions to those with at least 90% confidence. We have also implemented several efficiency and usability improvements to the V-FASTR web-based candidate review system. Overall, we found that time spent reviewing decreased and the fraction of interesting candidates increased. The classifier now classifies (and therefore filters) 80%-90% of the candidates, with an accuracy greater than 98%, leaving only the 10%-20% most promising candidates to be reviewed by humans.

  12. Detection of the optical afterglow of GRB 000630: Implications for dark bursts

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Jensen, B.L.; Gorosabel, J.

    2001-01-01

    We present the discovery of the optical transient of the long-duration gamma-ray burst GRB 000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04 +/- 0.08. The transient displayed...... a power-law decline characterized by a decay slope of alpha = -1.035 +/- 0.097. A deep image obtained 25 days after the burst shows no indication of a contribution from a supernova or a host galaxy at the position of the transient. The closest detected galaxy is a R = 324.68 +/- 0.15 galaxy 2.0 arcsec...... that i) based on the gamma-ray: properties of the current sample we cannot conclude that GRBs with no detected OTs belong to another class of GRBs than GRBs with detected OTs and ii) the majority (greater than or similar to 75%) of GRBs for which searches for optical afterglow have been unsuccessful...

  13. INTEGRAL detects an X-ray burst from SAX J1747.0-2853 with no detectable persistent emission

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Brandt, Søren Kristian; Kuulkers, Erik;

    2009-01-01

    A new season of observations for the INTEGRAL Galactic Bulge monitoring (see ATel #438) has started on 2009 Feb. 21st. During the latest observation between 2009 Feb 25 13:21 and 17:02 (UT) a type I X-ray burst from SAX J1747.0-2853 (1A 1743-288, aka GX .2-0.2) was detected by JEM-X at UT 14:50:5...

  14. Direct Collapse Black Holes Can Launch Gamma-Ray Bursts and Get Fat to Supermassive Black Holes?

    CERN Document Server

    Matsumoto, Tatsuya; Ioka, Kunihito; Heger, Alexander; Nakamura, Takashi

    2015-01-01

    The existence of black holes (BHs) of mass ~ 10^{9} M_sun at z > 6 is a big puzzle in astrophysics because even optimistic estimates of the accretion time are insufficient for stellar mass BHs of ~ 10 M_sun to grow into such supermassive BHs. A resolution of this puzzle might be the direct collapse of supermassive stars with mass M ~ 10^{5} M_sun into massive seed BHs. We find that if a jet is launched from the accretion disk around the central BH, the jet can break out the star because of the structure of the radiation pressure-dominated envelope. Such ultra-long gamma-ray bursts with duration of ~ 10^{4} - 10^{6} s and flux of 10^{-11} - 10^{-8} erg s^{-1} cm^{-2} could be detectable by Swift. We estimate an event rate of 10^{55} - 10^{56} erg. The resulting negative feedback delays the growth of the remnant BH by about 70 Myr or evacuates the host galaxy completely.

  15. Use of water-Cherenkov detectors to detect Gamma Ray Bursts at the Large Aperture GRB Observatory (LAGO)

    Energy Technology Data Exchange (ETDEWEB)

    Allard, D. [APC, CNRS et Universite Paris 7 (France); Allekotte, I. [Centro Atomico Bariloche, Instituto Balseiro (Argentina); Alvarez, C. [Facultad de Ciencias Fisico-Matematicas de la BUAP (Mexico); Asorey, H. [Centro Atomico Bariloche, Instituto Balseiro (Argentina); Barros, H. [Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of); Bertou, X. [Centro Atomico Bariloche, Instituto Balseiro (Argentina)], E-mail: bertou@cab.cnea.gov.ar; Burgoa, O. [Instituto de Investigaciones Fisicas, UMSA (Bolivia); Gomez Berisso, M. [Centro Atomico Bariloche, Instituto Balseiro (Argentina); Martinez, O. [Facultad de Ciencias Fisico-Matematicas de la BUAP (Mexico); Miranda Loza, P. [Instituto de Investigaciones Fisicas, UMSA (Bolivia); Murrieta, T.; Perez, G. [Facultad de Ciencias Fisico-Matematicas de la BUAP (Mexico); Rivera, H. [Instituto de Investigaciones Fisicas, UMSA (Bolivia); Rovero, A. [Instituto de Astronomia y Fisica del Espacio (Argentina); Saavedra, O. [Dipartimento di Fisica Generale and INFN, Torino (Italy); Salazar, H. [Facultad de Ciencias Fisico-Matematicas de la BUAP (Mexico); Tello, J.C. [Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of); Ticona Peralda, R.; Velarde, A. [Instituto de Investigaciones Fisicas, UMSA (Bolivia); Villasenor, L. [Facultad de Ciencias Fisico-Matematicas de la BUAP (Mexico); Instituto de Fisica y Matematicas, Universidad de Michoacan (Mexico)

    2008-09-21

    The Large Aperture GRB Observatory (LAGO) project aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique in ground-based water-Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Merida, 4765 m a.s.l.). We report on detector calibration and operation at high altitude, search for bursts in 4 months of preliminary data, as well as search for signal at ground level when satellites report a burst.

  16. Can Breath Test Detect Stomach Cancers Earlier?

    Science.gov (United States)

    ... news/fullstory_163342.html Can Breath Test Detect Stomach Cancers Earlier? New technology may also spot esophageal cancers ... the only way to diagnose esophageal cancer or stomach cancer is with endoscopy. This method is expensive, invasive ...

  17. Detectivity of Fe Kα Lines in Gamma-Ray Bursts by Cerenkov Line Mechanism

    Institute of Scientific and Technical Information of China (English)

    SU Jie; JIN Sheng-Zhen

    2005-01-01

    @@ The Fe Kα lines in gamma-ray bursts (GRBs) produced with the Cerenkov line mechan ism are studied. We theoretically predict the Fe Kα line luminosities in both the early (before 1 hour) and late (~ 1 day) afterglows. Assuming about 200 GRBs could be detected by Swift per year, we sampled the redshift of these GRBs using the Monte Carlo method according to the GRB formation rate derived from the statistical correlation between the spectral peak energy and the peak luminosity of GRBs.

  18. Search for Gravitational Waves Associated with γ-ray Bursts Detected by the Interplanetary Network

    Science.gov (United States)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Andersen, M.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Augustus, H.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauchrowitz, J.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Beker, M. G.; Belczynski, C.; Bell, A. S.; Bell, C.; Bergmann, G.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bosi, L.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burman, R.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castaldi, G.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Celerier, C.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Croce, R. P.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fazi, D.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Feroz, F.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Ha, J.; Hall, E. D.; Hamilton, W.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Holt, K.; Hopkins, P.; Horrom, T.; Hoske, D.; Hosken, D. J.; Hough, J.; Howell, E. J.

    2014-07-01

    We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10-2M⊙c2 at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  19. Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by the Interplanetary Network

    Science.gov (United States)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Blackbum, L.; Camp, J. B.; Gehrels, N.; Graff, P. B.; Slutsky, J.; Cline, T.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.

    2014-01-01

    We present the results of a search for gravitational waves associated with 223 gamma ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(exp-2) solar mass c(exp 2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  20. Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network.

    Science.gov (United States)

    Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Augustus, H; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Biwer, C; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Calderón Bustillo, J; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castaldi, G; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J-P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Croce, R P; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Dal Canton, T; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; DeBra, D; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fazi, D; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C J; Gushwa, K; Gustafson, E K; Gustafson, R; Ha, J; Hall, E D; Hamilton, W; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C-J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Holt, K; Hopkins, P; Horrom, T; Hoske, D; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Ingram, D R; Inta, R; Islas, G; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Haris, K; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G

    2014-07-04

    We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

  1. Can gamma ray bursts be used as effective tracers of star formation to high Z?

    Science.gov (United States)

    Beckman, John; Giammanco, Corrado

    Long duration gamma ray bursts (GRB's) have been identified as originating in type II SNa explosions, produced during the late stage evolution of massive stars. As the lifetimes of their progenitors are so short the GRB rate per unit (comoving) volume of space, on scales which include significant numbers of galaxies, could be proportional to the star formation rate (SFR), at least to the formation rate of massive stars. Unfortunately both theory and observation imply that those SNe which give rise to gamma ray bursts occur in stars of low metallicity, less than half an order of magnitude lower than solar. Here we examine the evidence and show that although some workers believe that it is possible to use local galaxies with GRB's to calibrate the SFR in more distant galaxies others claim that this may be possible given independent ways of determining the metallicities of the distant galaxies, while others suggest that it is too difficult, at least with present measurements, to use GRB's to determine the SFR at values of redshift higher than 5. We conclude that although their intrinsic power gives GRB's the facility to guide observers towards star forming galaxies, only by also using complementary indicators will we be able to make plausible determinations of the SFR as a function of epoch beyond z = 5, i.e. during the first 2 Gyr after the Big Bang.

  2. Probing pseudo-Dirac neutrino through detection of neutrino-induced muons from gamma ray burst neutrinos

    Indian Academy of Sciences (India)

    Debasish Majumdar

    2008-01-01

    The possibility to verify the pseudo-Dirac nature of neutrinos is investigated here via the detection of ultra-high energy neutrinos from distant cosmological objects like -ray bursts (GRBs). The very long baseline and the energy range from ∼TeV to ∼EeV for such neutrinos invoke the likelihood to probe very small pseudo-Dirac splittings. The expected secondary muons from such neutrinos that can be detected by a kilometer scale detector such as ICECUBE is calculated and compared with the same in the case of mass-flavour oscillations and for no oscillation cases. The calculated muon yields indicate that to probe such small pseudo-Dirac splittings one needs to look for a nearby GRB (red shift ∼ 0:03 or less) whereas for a distant GRB ( ∼ 1) the flux will be much depleted and such phenomenon cannot be distinguished. Also calculated are the muon-to-shower ratios.

  3. Can life survive Gamma-Ray Bursts in the high-redshift universe?

    CERN Document Server

    Li, Ye

    2015-01-01

    Nearby Gamma-Ray Bursts (GRBs) have been proposed as a possible cause of mass extinctions on Earth. Due to the higher event rate of GRBs at higher redshifts, it has been speculated that life as we know it may not survive above a certain redshift (e.g. $z>0.5$). We examine the duty cycle of lethal (life-threatening) GRBs in the solar neighborhood, in the Sloan Digital Sky Survey (SDSS) galaxies and GRB host galaxies, with the dependence of the long GRB rate on star formation and metallicity properly taken into account. We find that the number of lethal GRBs attacking Earth within the past 500 Myr ($\\sim$ epoch of the Ordovician mass extinction) is $0.93$. The number of lethal GRBs hitting a certain planet increases with redshift, thanks to the increasing star formation rate and decreasing metallicity in high-$z$ galaxies. Taking 1 per 500 Myr as a conservative duty cycle for life to survive, as evidenced by our existence, we find that there are still a good fraction of SDSS galaxies beyond $z=0.5$ where the GR...

  4. Embedded Detection and Correction of SEU Bursts in SRAM Memories Used as Radiation Detectors

    CERN Document Server

    Secondo, R.; Danzeca, S.; Losito, R.; Peronnard, P.; Masi, A.; Brugger, M.; Dusseau, L.

    2016-01-01

    SRAM memories are widely used as particle fluence detectors in high radiation environments, such as in the Radiation Monitoring System (RadMon) currently in operation in the CERN accelerator complex. Multiple Cell Upsets (MCUs), arising from micro-latchup events, are characterized by a large number of SEUs, ultimately affecting the measurement of particle fluxes and resulting in corrupted data and accuracy losses. A study of the generation of this type of SEU bursts was performed on an 8 Mbit 90-nm SRAM memory. Experimental tests were carried out with a focused beam of protons on target as well as in a mixed field environment dominated by high energy hadrons. A solution approach using an on-line detection and correction algorithm embedded on an FPGA was investigated and evaluated for use on a RadMon device.

  5. INTEGRAL/JEM-X detection of a type-I X-ray burst from MAXI J1421-613

    DEFF Research Database (Denmark)

    Bozzo, E.; Bazzano, A.; Kuulkers, Erik

    2014-01-01

    During the Galactic Plane Scan performed on 2014 January 10, the two JEM-X instruments on-board INTEGRAL detected a type-I X-ray burst from the newly discovered X-ray transient MAXI J1421-613 (ATels #5750, #5751, #5759) over the 5 ks in which the source was in the instruments field of view. The o...... (translating into a luminosity of 1.3E37 erg/s at 8 kpc; 3-10 keV). We estimated a persistent flux outside the burst of 7E-10 erg/cm^2/s (3-25 keV). This detection reveals that MAXI J1421-613 is a newly discovered X-ray bursting transient source, thus hosting an accreting neutron star....

  6. 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.

  7. Can Life Survive Gamma-Ray Bursts in the High-redshift Universe?

    Science.gov (United States)

    Li, Ye; Zhang, Bing

    2015-09-01

    Nearby gamma-ray bursts (GRBs) have been proposed as a possible cause of mass extinctions on Earth. Due to the higher event rate of GRBs at higher redshifts, it has been speculated that life as we know it may not survive above a certain redshift (e.g., z\\gt 0.5). We examine the duty cycle of lethal (life-threatening) GRBs in the solar neighborhood, in the Sloan Digital Sky Survey (SDSS) galaxies, and GRB host galaxies, with the dependence of the long GRB rate on star formation and metallicity properly taken into account. We find that the number of lethal GRBs attacking Earth within the past 500 Myr (˜epoch of the Ordovician mass extinction) is 0.93. The number of lethal GRBs hitting a certain planet increases with redshift, as a result of the increasing star formation rate (SFR) and decreasing metallicity in high-z galaxies. Taking 1 per 500 Myr as a conservative duty cycle for life to survive, as evidenced by our existence, we find that there is still a good fraction of SDSS galaxies beyond z=0.5 where the GRB rate at half-mass radius is lower than this value. We derive the fraction of such benign galaxies as a function of redshift through Monte Carlo simulations, and we find that the fraction is ˜ 50% at z˜ 1.5 and ˜ 10% even at z˜ 3. The mass distribution of benign galaxies is dominated by Milky Way-like ones, due to their commonness, relatively large mass, and low SFR. GRB host galaxies are among the most dangerous ones.

  8. On the prospects of gamma-ray burst detection in the TeV band

    CERN Document Server

    Vurm, Indrek

    2016-01-01

    A gamma-ray burst (GRB) jet running into an external medium is expected to generate luminous GeV-TeV emission lasting from minutes to several hours. The high-energy emission results from inverse Compton upscattering of prompt and afterglow photons by shock-heated {\\it thermal} plasma. At its peak the high-energy radiation carries a significant fraction of the power dissipated at the forward shock. We discuss in detail the expected TeV luminosity, using a robust "minimal" emission model. Then, using the statistical properties of the GRB population (luminosity function, redshift distribution, afterglow energy) we simulate the expected detection rates of GRBs by current and upcoming atmospheric Cherenkov instruments. We find that GRBs exploding into a low-density interstellar medium must produce TeV emission that would have already been detected by the currently operating Cherenkov telescopes. The absence of detections is consistent with explosions into a dense wind of the GRB progenitor. If the typical environm...

  9. Detection of three Gamma-Ray Burst host galaxies at $z\\sim6$

    CERN Document Server

    McGuire, J T W; Levan, A J; Trenti, M; Stanway, E R; Shull, J M; Wiersema, K; Perley, D A; Starling, R L C; Bremer, M; Stocke, J T; Hjorth, J; Rhoads, J E; Levesque, E M; Robertson, B; Fynbo, J P U; Ellis, R S; Fruchter, A S; Perna, R

    2015-01-01

    Gamma-ray bursts allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their immense luminosities and association with deaths of massive stars. We present {\\em Hubble Space Telescope} Wide Field Camera 3 detections of three {\\em Swift} GRBs lying at redshifts $z = 5.913$ (GRB 130606A), $z = 6.295$ (GRB 050904), and $z = 6.327$ (GRB 140515A) in the F140W (wide-$JH$ band, $\\lambda_{\\rm{obs}}\\sim1.4\\,\\mu m$) filter. The hosts have magnitudes (corrected for Galactic extinction) of $m_{\\rm{\\lambda_{obs},AB}}= 26.26^{+0.12}_{-0.14}, 27.63^{+0.16}_{-0.18},$ and $28.23^{+0.24}_{-0.30}$ respectively. In all three cases the probability of chance coincidence of lower redshift galaxies is $\\lesssim1.5\\%$, indicating that the detected galaxies are most likely the GRB hosts. These are the first detections of high redshift ($z > 5$) GRB host galaxies in emission. The galaxies have luminosities in the range $0.1-0.7\\,L^{*}_{z=6}$ (with $M_{1600}^{*}=-20.95\\pm0.12$), along with half-light radii...

  10. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-15

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

  11. Spectral evolution of gamma-ray bursts detected by the SIGNE experiment. 1: Correlation between intensity and spectral hardness

    Science.gov (United States)

    Kargatis, Vincent E.; Liang, Edison P.; Hurley, Kevin C.; Barat, C.; Eveno, E.; Niel, M.

    1994-01-01

    We study the continuum spectral evolution of 16 gamma-ray bursts detected by the Franco-Soviet SIGNE experiment in 1981-1982 by fitting time resolved (0.5 s) spectra in count space with simple thermal bremsstrahlung and synchrotron models. We find that there is no single characteristic of spectral evolution: we see hard-to-soft, soft-to-hard, luminosity-hardness tracking, and chaotic evolution. We perform correlation studies between instantaneous burst intensity and spectral temperature for seven bursts. While we basically confirm the existence of a correlation between these variables as originally claimed by Golenetskii et al. (1983) we find higher values and a broader range of correlation indices.

  12. A Burst to See

    Science.gov (United States)

    2008-04-01

    , able to record the event with unprecedented temporal resolution.. "These very early detections (just seconds after the beginning of the burst) showed the object to be so bright that it would have been visible just with the unaided eye," says Stefano Covino, from the REM team. "It was astonishing to see how rapidly the source varied during the observations," adds Sergey Karpov, of the TORTORA team. Astronomers use the so-called magnitude scale, an inverse scale where fainter objects have larger magnitudes. In dark sites, the most acute of human eyes can distinguish sources as faint as magnitude 6. GRB 080319B was slightly brighter than this limit, although for just less than a minute. The 8.2-metre ESO Very Large Telescope also reacted to the gamma-ray burst, thanks to a special procedure known as the rapid-response mode (see ESO 17/07), which allows automatic observations with no human intervention. The high-resolution spectrograph UVES could collect exquisite data starting only 10 minutes after the burst, following requests by Fabrizio Fiore and his team. Another team then used also UVES to determine the distance of the burst. "Despite its stunning brightness, the burst exploded in a galaxy 7.5 billion light years away," says Paul Vreeswijk, who led the second team. "It was therefore not only apparently bright, but also intrinsically very luminous. Indeed, it reached the brightest optical luminosity ever recorded for any astronomical object. For comparison, should the burst have exploded in our Galaxy, it would have lit up the night sky for several minutes as if it were daytime."

  13. The REM Telescope Detecting the Near Infra-Red Counterparts of Gamma-Ray Bursts and the Prompt Behaviour of Their Optical Continuum

    CERN Document Server

    Zerbi, F M; Ghisellini, G; Rodono, M

    2001-01-01

    Observations of the prompt afterglow of Gamma Ray Burst events are unanimously considered of paramount importance for GRB science and related cosmology. Such observations at NIR wavelengths are even more promising allowing one to monitor high-z Ly-alpha absorbed bursts as well as events occurring in dusty star-forming regions. In these pages we present REM (Rapid Eye Mount), a fully robotized fast slewing telescope equipped with a high throughput NIR (Z', J, H, K') camera dedicated to detecting the prompt IR afterglow. REM can discover objects at extremely high red-shift and trigger large telescopes to observe them. The REM telescope will simultaneously feed ROSS (REM Optical Slitless spectrograph) via a dichroic. ROSS will intensively monitor the prompt optical continuum of GRB afterglows. The synergy between REM-IR cam and ROSS makes REM a powerful observing tool for any kind of fast transient phenomena.

  14. Spatial variation in automated burst suppression detection in pharmacologically induced coma.

    Science.gov (United States)

    An, Jingzhi; Jonnalagadda, Durga; Moura, Valdery; Purdon, Patrick L; Brown, Emery N; Westover, M Brandon

    2015-01-01

    Burst suppression is actively studied as a control signal to guide anesthetic dosing in patients undergoing medically induced coma. The ability to automatically identify periods of EEG suppression and compactly summarize the depth of coma using the burst suppression probability (BSP) is crucial to effective and safe monitoring and control of medical coma. Current literature however does not explicitly account for the potential variation in burst suppression parameters across different scalp locations. In this study we analyzed standard 19-channel EEG recordings from 8 patients with refractory status epilepticus who underwent pharmacologically induced burst suppression as medical treatment for refractory seizures. We found that although burst suppression is generally considered a global phenomenon, BSP obtained using a previously validated algorithm varies systematically across different channels. A global representation of information from individual channels is proposed that takes into account the burst suppression characteristics recorded at multiple electrodes. BSP computed from this representative burst suppression pattern may be more resilient to noise and a better representation of the brain state of patients. Multichannel data integration may enhance the reliability of estimates of the depth of medical coma.

  15. Rapid Detection of Neutrophil Oxidative Burst Capacity is Predictive of Whole Blood Cytokine Responses.

    Directory of Open Access Journals (Sweden)

    Philip J Vernon

    Full Text Available Maladaptive immune responses, particularly cytokine and chemokine-driven, are a significant contributor to the deleterious inflammation present in many types of injury and infection. Widely available applications to rapidly assess individual inflammatory capacity could permit identification of patients at risk for exacerbated immune responses and guide therapy. Here we evaluate neutrophil oxidative burst (NOX capacity measured by plate reader to immuno-type Rhesus Macaques as an acute strategy to rapidly detect inflammatory capacity and predict maladaptive immune responses as assayed by cytokine array.Whole blood was collected from anesthetized Rhesus Macaques (n = 25 and analyzed for plasma cytokine secretion (23-plex Luminex assay and NOX capacity. For cytokine secretion, paired samples were either unstimulated or ex-vivo lipopolysaccharide (LPS-stimulated (100μg/mL/24h. NOX capacity was measured in dihydrorhodamine-123 loaded samples following phorbol 12-myristate 13-acetate (PMA/ionomycin treatment. Pearson's test was utilized to correlate NOX capacity with cytokine secretion, p<0.05 considered significant.LPS stimulation induced secretion of the inflammatory molecules G-CSF, IL-1β, IL-1RA, IL-6, IL-10, IL-12/23(p40, IL-18, MIP-1α, MIP-1β, and TNFα. Although values were variable, several cytokines correlated with NOX capacity, p-values≤0.0001. Specifically, IL-1β (r = 0.66, IL-6 (r = 0.74, the Th1-polarizing cytokine IL-12/23(p40 (r = 0.78, and TNFα (r = 0.76 were strongly associated with NOX.NOX capacity correlated with Th1-polarizing cytokine secretion, indicating its ability to rapidly predict inflammatory responses. These data suggest that NOX capacity may quickly identify patients at risk for maladaptive immune responses and who may benefit from immuno-modulatory therapies. Future studies will assess the in-vivo predictive value of NOX in animal models of immune-mediated pathologies.

  16. No supernovae detected in two long-duration gamma-ray bursts.

    Science.gov (United States)

    Watson, D; Fynbo, J P U; Thöne, C C; Sollerman, J

    2007-05-15

    There is strong evidence that long-duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. In the standard version of the collapsar model, a broad-lined and luminous Type Ic core-collapse supernova (SN) accompanies the GRB. This association has been confirmed in observations of several nearby GRBs. Recent observations show that some long-duration GRBs are different. No SN emission accompanied the long-duration GRBs 060505 and 060614 down to limits fainter than any known Type Ic SN and hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration. Furthermore, the bursts originated in star-forming galaxies, and in the case of GRB 060505, the burst was localized to a compact star-forming knot in a spiral arm of its host galaxy. We find that the properties of the host galaxies, the long duration of the bursts and, in the case of GRB 060505, the location of the burst within its host, all imply a massive stellar origin. The absence of an SN to such deep limits therefore suggests a new phenomenological type of massive stellar death.

  17. Search for gravitational waves associated with gamma-ray bursts detected by the InterPlanetary Network

    CERN Document Server

    Aasi, J; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Augustus, H; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bischof, H; Bitossi, M; Biwer, C; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campanelli, M; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castaldi, G; Castiglia, A; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Croce, R P; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; DeBra, D; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fazi, D; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C J; Gushwa, K; Gustafson, E K; Gustafson, R; Ha, J; Hall, E D; Hamilton, W; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Hopkins, P; Horrom, T; Hoske, D; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Ingram, D R; Inta, R; Islas, G; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N G; Kim, N; Kim, S; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, D Nanda; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lam, P K; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, J; Lee, P J; Leonardi, M; Leong, J R; Roux, A Le; Leroy, N; Letendre, N; Levin, Y; Levine, B; Lewis, J; Li, T G F; Libbrecht, K; Libson, A; Lin, A C; Littenberg, T B; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lopez, E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Lubinski, M J; Lück, H; Lundgren, A P; Ma, Y; Macdonald, E P; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R; Mageswaran, M; Maglione, C; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mangini, N M; Mansell, G; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Mavalvala, N; May, G; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; McLin, K; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meinders, M; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyer, M S; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Miller, J; Minenkov, Y; Mingarelli, C M F; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Moggi, A; Mohan, M; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nielsen, A B; Nissanke, S; Nitz, A H; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Oh, J J; Oh, S H; Ohme, F; Omar, S; Oppermann, P; Oram, R; O'Reilly, B; Ortega, W; O'Shaughnessy, R; Osthelder, C; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palashov, O; Palomba, C; Pan, H; Pan, Y; Pankow, C; Paoletti, F; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Pele, A; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poteomkin, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S; Prestegard, T; Price, L R; Prijatelj, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qin, J; Quetschke, V; Quintero, E; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Ramirez, K; Rapagnani, P; Raymond, V; Razzano, M; Recchia, S; Reed, C M; Regimbau, T; Reid, S; Reitze, D H; Reula, O; Rhoades, E; Ricci, F; Riesen, R; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Roddy, S B; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J R; Sankar, S; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Scheuer, J; Schilling, R; Schilman, M; Schmidt, P; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D A; Shah, S; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Singh, R; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, R J E; Smith-Lefebvre, N D; Son, E J; Sorazu, B; Souradeep, T; Staley, A; Stebbins, J; Steinke, M; Steinlechner, J; Steinlechner, S; Stephens, B C; Steplewski, S; Stevenson, S; Stone, R; Stops, D; Strain, K A; Straniero, N; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Tacca, M; Talukder, D; Tanner, D B; Tao, J; Tarabrin, S P; Taylor, R; Tellez, G; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Tshilumba, D; Tuennermann, H; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vyachanin, S P; Wade, A R; Wade, L; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, M; Wang, X; Ward, R L; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; White, D J; Whiting, B F; Wiesner, K; Wilkinson, C; Williams, K; Williams, L; Williams, R; Williams, T D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Wolovick, N; Worden, J; Wu, Y; Yablon, J; Yakushin, I; Yam, W; Yamamoto, H; Yancey, C C; Yang, H; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J -P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, H; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Aptekar, R L; Atteia, J L; Cline, T; Connaughton, V; Frederiks, D D; Golenetskii, S V; Hurley, K; Krimm, H A; Marisaldi, M; Pal'shin, V D; Palmer, D; Svinkin, D S; Terada, Y; von Kienlin, A

    2014-01-01

    We present the results of a search for gravitational waves associated with 223 gamma-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational-wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational-wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational-wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational-wave da...

  18. Magnetar Twists: Fermi/Gamma ray Burst Monitor (GBM) detection of SGR 1550-5418

    CERN Document Server

    Kaneko, Y; Kouveliotou, C; Ramirez-Ruiz, E; Granot, J; van der Horst, A J; Watts, A L; Finger, M H; Gehrels, N; Pe'er, A; van der Klis, M; von Kienlin, A; Wachter, S; Wilson-Hodge, C A; Woods, P M

    2009-01-01

    SGR 1550-5418 (previously known as AXP 1E 1547.0-5408) went into three active bursting episodes in 2008 October and in 2009 January and March, emitting hundreds of typical Soft Gamma Repeater (SGR) bursts in soft gamma rays. The second episode was especially intense, and our untriggered burst search on Fermi/GBM data (8-1000 keV) revealed ~450 bursts emitted over 24 hours during the peak of this activity. Using the GBM data, we identified a ~150-s-long enhanced persistent emission during 2009 January 22 that exhibited intriguing timing and spectral properties: (i) clear pulsations up to ~110 keV at the spin period of the neutron star (P ~2.07 s, the fastest of all magnetars), (ii) an additional (to a power-law) blackbody component required for the enhanced emission spectra with kT ~17 keV, (iii) pulsed fraction that is strongly energy dependent and highest in the 50-74 keV energy band. A total isotropic-equivalent energy emitted during this enhanced emission is estimated to be 4.3 x 10^{40} ergs. We conclude ...

  19. No supernovae detected in two long-duration Gamma-Ray Bursts

    CERN Document Server

    Watson, D; Th"one, C C; Sollerman, J

    2007-01-01

    There is strong evidence that long duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. In the standard version of the Collapsar model, a broad-lined and luminous Type Ic core-collapse supernova (SN) accompanies the GRB. This association has been confirmed in observations of several nearby GRBs. Recent observations show that some long duration GRBs are different. No SN emission accompanied the long duration GRBs 060505 and 060614 down to limits fainter than any known Type Ic SN and hundreds of times fainter than the archetypal SN1998bw that accompanied GRB980425. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration. Furthermore, the bursts originated in star-forming galaxies, and in the case of GRBs060505 the burst was localised to a compact star-forming knot in a spiral arm of its host galaxy. We find that the properties of the host galaxies, the long duration of the bursts and, i...

  20. FRBCAT: The Fast Radio Burst Catalogue

    Science.gov (United States)

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

    2016-09-01

    Here, we present a catalogue of known Fast Radio Burst 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 re-processed 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 Fast Radio Burst population as it grows.

  1. Detection of an optical transient following the 13 March 2000 short/hard gamma-ray burst

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Ceron, J.M.C.; Gorosabel, J.

    2002-01-01

    for bursts of the long, soft type). The fact that only prompt optical emission has been detected (but no afterglow emission at all, as supported by theoretical models) might explain why no optical counterparts have ever been found for short, hard GRBs. This fact suggests that most short bursts might occur......We imaged the error box of a gamma-ray burst of the short (0.5 s), hard type (GRB 000313), with the BOOTES-1 experiment in southern Spain, starting 4 min after the gamma-ray event, in the I-band. A bright optical transient (OT 000313) with I = 9.4 +/- 0.1 was found in the BOOTES-1 image, close...... to the error box (3sigma) provided by BATSE. Late time VRI K'-band deep observations failed to reveal an underlying host galaxy. If the OT 000313 is related to the short, hard GRB 000313, this would be the first optical counterpart ever found for this kind of events (all counterparts to date have been found...

  2. Detection of an optical transient following the 13 March 2000 short/hard gamma-ray burst

    Science.gov (United States)

    Castro-Tirado, A. J.; Castro Cerón, J. M.; Gorosabel, J.; Páta, P.; Soldán, J.; Hudec, R.; Jelinek, M.; Topinka, M.; Bernas, M.; Mateo Sanguino, T. J.; de Ugarte Postigo, A.; Berná, J. Á.; Henden, A.; Vrba, F.; Canzian, B.; Harris, H.; Delfosse, X.; de Pontieu, B.; Polcar, J.; Sánchez-Fernández, C.; de la Morena, B. A.; Más-Hesse, J. M.; Torres Riera, J.; Barthelmy, S.

    2002-10-01

    We imaged the error box of a gamma-ray burst of the short (0.5 s), hard type (GRB 000313), with the BOOTES-1 experiment in southern Spain, starting 4 min after the gamma -ray event, in the I-band. A bright optical transient (OT 000313) with I = 9.4 +/- 0.1 was found in the BOOTES-1 image, close to the error box (3sigma ) provided by BATSE. Late time VRIK'-band deep observations failed to reveal an underlying host galaxy. If the OT 000313 is related to the short, hard GRB 000313, this would be the first optical counterpart ever found for this kind of events (all counterparts to date have been found for bursts of the long, soft type). The fact that only prompt optical emission has been detected (but no afterglow emission at all, as supported by theoretical models) might explain why no optical counterparts have ever been found for short, hard GRBs. This fact suggests that most short bursts might occur in a low-density medium and favours the models that relate them to binary mergers in very low-density environments. Based in part on observations made with the BOOTES instruments in South Spain.

  3. Detection of an optical transient following the 13 March 2000 short/hard gamma-ray burst

    CERN Document Server

    Castro-Tirado, A J; Gorosabel, J; Pata, P; Soldan, J; Hudec, R; Jelinek, M; Topinka, M A; Bernas, M; Sanguino, T J M; De Postigo, A U; Berna, J A; Henden, A A; Vrba, F J; Canzian, B; Harris, H; Delfosse, X; De Pontieu, B; Polcar, J; Sánchez-Fernández, C; De la Morena, B A; Mas-Hesse, J M; Riera, J T; Barthelmy, S D

    2002-01-01

    We imaged the error box of a gamma-ray burst of the short (0.5 s), hard type (GRB 000313), with the BOOTES-1 experiment in southern Spain, starting 4 min after the gamma-ray event, in the I-band. A bright optical transient (OT 000313) with I = 9.4 +/- 0.1 was found in the BOOTES-1 image, close to the error box (3-sigma) provided by BATSE. Late time VRIK'-band deep observations failed to reveal an underlying host galaxy. If the OT 000313 is related to the short, hard GRB 000313, this would be the first optical counterpart ever found for this kind of events (all counterparts to date have been found for bursts of the long, soft type). The fact that only prompt optical emission has been detected (but no afterglow emission at all, as supported by theoretical models) might explain why no optical counterparts have ever been found for short, hard GRBs.This fact suggests that most short bursts might occur in a low-density medium and favours the models that relate them to binary mergers in very low-density enviroments.

  4. Very Long Baseline Interferometry Experiment on Giant Radio Pulses of Crab Pulsar toward Fast Radio Burst Detection

    CERN Document Server

    Takefuji, K; Kondo, T; Mikami, R; Takeuchi, H; Misawa, H; Tsuchiya, F; Kita, H; Sekido, M

    2016-01-01

    We report on a very long baseline interferometry (VLBI) experiment on giant radio pulses (GPs) from the Crab pulsar in the radio 1.4 to 1.7 GHz range to demonstrate a VLBI technique for searching for fast radio bursts (FRBs). We carried out the experiment on 26 July 2014 using the Kashima 34 m and Usuda 64 m radio telescopes of the Japanese VLBI Network (JVN) with a baseline of about 200 km. During the approximately 1 h observation, we could detect 35 GPs by high-time-resolution VLBI. Moreover, we determined the dispersion measure (DM) to be 56.7585 +/- 0.0025 on the basis of the mean DM of the 35 GPs detected by VLBI. We confirmed that the sensitivity of a detection of GPs using our technique is superior to that of a single-dish mode detection using the same telescope.

  5. Off-axis emission of short gamma-ray bursts and the detectability of electromagnetic counterparts of gravitational wave detected binary mergers

    CERN Document Server

    Lazzati, Davide; Morsony, Brian J; Workman, Jared C

    2016-01-01

    We present calculations of the wide angle emission of short-duration gamma-ray bursts from compact binary merger progenitors. Such events are expected to be localized by their gravitational wave emission, fairly irrespective of the orientation of the angular momentum vector of the system, along which the gamma-ray burst outflow is expected to propagate. We show that both the prompt and afterglow emission are dim and challenging to detect for observers lying outside of the cone within which the relativistic outflow is propagating. If the jet initially propagates through a baryon contaminated region surrounding the merger site, however, a hot cocoon forms around it. The cocoon subsequently expands quasi-isotropically producing its own prompt emission and external shock powered afterglow. We show that the cocoon afterglow peaks a few hours to a few days after the burst and is detectable for up to a few weeks at all wavelengths. For a significant fraction of the gravitationally-detected neutron-star-binary merger...

  6. Implications for Understanding Short Gamma-Ray Bursts Detected by {\\it Swift}

    CERN Document Server

    Shao, Lang; Fan, Yi-Zhong; Zhang, Fu-Wen; Jin, Zhi-Ping; Wei, Da-Ming

    2011-01-01

    In an effort to understand the puzzle of classifying Gamma-Ray Bursts (GRBs), we have a systematic study of {\\it Swift} GRBs and investigate several issues on short GRBs. Though short GRBs have a short ($\\lesssim2$ s) prompt duration as monitored by {\\it Swift} Burst Alert Telescope (BAT), the composite light curves including both the prompt and afterglow emission suggest that most of them have a similar radiative feature as the long GRBs. Besides, some well-studied short GRBs might also have an intrinsically long prompt duration, which renders them a type of short GRB imposters. Genuine short GRBs might be rare so that to discriminate the observed short GRBs is, not surprisingly, troublesome. In particular, the observational biases in the host identification and redshift measurement of GRBs should be taken with great caution. The redshift distribution which has been proposed to be different for long and short GRBs might have been strongly affected by the measurement methods.

  7. Development of a modular CdTe detector plane for gamma-ray burst detection below 100 keV

    OpenAIRE

    Ehanno, M.; Amoros, C.; Barret, D.; Lacombe, K.; Pons, R.; Rouaix, G.; Gevin, O.; Limousin, O.; Lugiez, F.; Bardoux, A.; Penquer, A.

    2007-01-01

    We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produc...

  8. Interaction between cellular voltage-sensitive conductance and network parameters in a model of neocortex can generate epileptiform bursting.

    Energy Technology Data Exchange (ETDEWEB)

    van Drongelen, W.; Lee, H. C.; Koch, H.; Elsen, F.; Carroll, M. S.; Hereld, M.; Stevens, R. L.; Mathematics and Computer Science; Univ. of Chicago

    2004-01-01

    We examined the effects of both intrinsic neuronal membrane properties and network parameters on oscillatory activity in a model of neocortex. A scalable network model with six different cell types was built with the pGENESIS neural simulator. The neocortical network consisted of two types of pyramidal cells and four types of inhibitory interneurons. All cell types contained both fast sodium and delayed rectifier potassium channels for generation of action potentials. A subset of the pyramidal neurons contained an additional slow inactivating (persistent) sodium current (NaP). The neurons with the NaP current showed spontaneous bursting activity in the absence of external stimulation. The model also included a routine to calculate a simulated electroencephalogram (EEG) trace from the population activity. This revealed emergent network behavior which ranged from desynchronized activity to different types of seizure-like bursting patterns. At settings with weaker excitatory network effects, the propensity to generate seizure-like behavior increased. Strong excitatory network connectivity destroyed oscillatory behavior, whereas weak connectivity enhanced the relative importance of the spontaneously bursting cells. Our findings are in contradiction with the general opinion that strong excitatory synaptic and/or insufficient inhibition effects are associated with seizure initiation, but are in agreement with previously reported behavior in neocortex.

  9. A Search for Prompt Very High Energy Emission from Satellite-detected Gamma-ray Bursts using Milagro

    CERN Document Server

    Parkinson, P M Saz

    2007-01-01

    Gamma-ray bursts (GRBs) have been detected up to GeV energies and are predicted by many models to emit in the very high energy (VHE, > 100 GeV) regime too. Detection of such emission would allow us to constrain GRB models. Since its launch, in late 2004, the Swift satellite has been locating GRBs at a rate of approximately 100 per year. The rapid localization and follow-up in many wavelengths has revealed new and unexpected phenomena, such as delayed emission in the form of bright X-ray flares. The Milagro gamma-ray observatory is a wide field of view (2 sr) instrument employing a water Cherenkov detector to continuously ($>$ 90% duty cycle) observe the overhead sky in the 100 GeV to 100 TeV energy range. Over 100 GRBs are known to have been in the field of view of Milagro since January 2000, including 57 since the launch of Swift (through May 2007). We discuss the results of the searches for prompt emission from these bursts, as well as for delayed emission from the X-ray flares observed in some of the Swift...

  10. In Situ Detection of Strong Langmuir Turbulence Processes in Solar Type III Radio Bursts

    Science.gov (United States)

    Golla, Thejappa; Macdowall, Robert J.; Bergamo, M.

    2012-01-01

    The high time resolution observations obtained by the WAVES experiment of the STEREO spacecraft in solar type III radio bursts show that Langmuir waves often occur as intense localized wave packets. These wave packets are characterized by short durations of only a few ms and peak intensities, which well exceed the supersonic modulational instability (MI) thresholds. These timescales and peak intensities satisfy the criterion of the solitons collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets consist of primary spectral peaks corresponding to beam-resonant Langmuir waves, two or more sidebands corresponding to down-shifted and up-shifted daughter Langmuir waves, and low frequency enhancements below a few hundred Hz corresponding to daughter ion sound waves. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the modulational instability (MI). Moreover, the tricoherences, computed using trispectral analysis techniques show that these spectral components are coupled to each other with a high degree of coherency as expected of the MI type of four wave interactions. The high intensities, short scale lengths, sideband spectral structures and low frequency spectral enhancements and, high levels of tricoherences amongst the spectral components of these wave packets provide unambiguous evidence for the supersonic MI and related strong turbulence processes in type III radio bursts. The implication of these observations include: (1) the MI and related strong turbulence processes often occur in type III source regions, (2) the strong turbulence processes probably play very important roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation at the fundamental and second harmonic of the electron plasma frequency, fpe, and (3) the Langmuir collapse probably follows the route of MI in type III radio bursts.

  11. Bursts from the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Silk, J. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)]. E-mail: les@mppmu.mpg.de

    2006-07-27

    Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of pheno associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse.

  12. 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...

  13. Magnetar Bursts

    Science.gov (United States)

    Kouveliotou, Chryssa

    2014-01-01

    The Fermi/Gamma-ray Burst Monitor (GBM) was launched in June 2008. During the last five years the instrument has observed several hundreds of bursts from 8 confirmed magnetars and 19 events from unconfirmed sources. I will discuss the results of the GBM magnetar burst catalog, expand on the different properties of their diverse source population, and compare these results with the bursting activity of past sources. I will then conclude with thoughts of how these properties fit the magnetar theoretical models.

  14. Dynamic encoding of natural luminance sequences by LGN bursts.

    Directory of Open Access Journals (Sweden)

    Nicholas A Lesica

    2006-07-01

    Full Text Available In the lateral geniculate nucleus (LGN of the thalamus, visual stimulation produces two distinct types of responses known as tonic and burst. Due to the dynamics of the T-type Ca(2+ channels involved in burst generation, the type of response evoked by a particular stimulus depends on the resting membrane potential, which is controlled by a network of modulatory connections from other brain areas. In this study, we use simulated responses to natural scene movies to describe how modulatory and stimulus-driven changes in LGN membrane potential interact to determine the luminance sequences that trigger burst responses. We find that at low resting potentials, when the T channels are de-inactivated and bursts are relatively frequent, an excitatory stimulus transient alone is sufficient to evoke a burst. However, to evoke a burst at high resting potentials, when the T channels are inactivated and bursts are relatively rare, prolonged inhibitory stimulation followed by an excitatory transient is required. We also observe evidence of these effects in vivo, where analysis of experimental recordings demonstrates that the luminance sequences that trigger bursts can vary dramatically with the overall burst percentage of the response. To characterize the functional consequences of the effects of resting potential on burst generation, we simulate LGN responses to different luminance sequences at a range of resting potentials with and without a mechanism for generating bursts. Using analysis based on signal detection theory, we show that bursts enhance detection of specific luminance sequences, ranging from the onset of excitatory sequences at low resting potentials to the offset of inhibitory sequences at high resting potentials. These results suggest a dynamic role for burst responses during visual processing that may change according to behavioral state.

  15. Two types of softening detected in X-ray afterglows of Swift bursts: internal and external shock origins?

    CERN Document Server

    Qin, Y -P; Fan, J H; Lu, R -J

    2008-01-01

    The softening process observed in the steep decay phase of early X-ray afterglows of Swift bursts has remained a puzzle since its discovery. The softening process can also be observed in the later phase of the bursts and its cause has also been unknown. Recently, it was suggested that, influenced by the curvature effect, emission from high latitudes would shift the Band function spectrum from higher energy band to lower band, and this would give rise to the observed softening process accompanied by a steep decay of the flux density. The curvature effect scenario predicts that the terminating time of the softening process would be correlated with the duration of the process. In this paper, based on the data from the UNLV GRB group web-site, we found an obvious correlation between the two quantities. In addition, we found that the softening process can be divided into two classes: the early type softening ($t_{s,max}\\leq "4000"s$) and the late type softening ($t_{s,max} > "4000"s$). The two types of softening s...

  16. The effect of signal-temporal uncertainty on detection in bursts of noise or a random-frequency complex

    Science.gov (United States)

    Bonino, Angela Yarnell; Leibold, Lori J.

    2008-01-01

    This study examined the effect of signal-temporal uncertainty on detection of a 120-ms, 1-kHz tone in the presence of a continuous sequence of 120-ms bursts of either a broadband noise or a random-frequency, two-tone complex. Using the method of constant stimuli, signal-temporal uncertainty was defined as the difference in threshold across temporally uncertain and temporally defined listening conditions. Results indicted an average effect of signal-temporal uncertainty of 2 dB for the noise masker compared to 9 dB for the random-frequency, two-tone masker. These results suggest that signal-temporal uncertainty may be more detrimental for conditions in which informational masking dominates performance. PMID:19045685

  17. 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.

  18. CMEs and frequency cutoff of solar bursts

    Science.gov (United States)

    Stanislavsky, Al.; Konovalenko, Al.; Koval, Ar.; Volvach, Y.; Zarka, P.

    2016-05-01

    Radio observations of solar bursts with high-frequency cutoff by the radio telescope UTR-2 (near Kharkiv, Ukraine) at 8-33 MHz on 17-19 August 2012 are presented. Such cutoff may be attributed to the emergence of the burst sources behind limb of the Sun with respect to an observer on the Earth. The events are strongly associated with solar eruptions occurred in a new active region. Ray tracing simulations show that the CMEs play a constructive role for the behind-limb bursts to be detected in ground-based observations. Likely, due to tunnel-like cavities with low density in CMEs, the radio emission of behind-limb solar bursts can be directed towards the Earth.

  19. A real-time fast radio burst: polarization detection and multiwavelength follow-up

    CERN Document Server

    Petroff, E; Barr, E D; Barsdell, B R; Bhat, N D R; Bian, F; Burke-Spolaor, S; Caleb, M; Champion, D; Chandra, P; Da Costa, G; Delvaux, C; Flynn, C; Gehrels, N; Greiner, J; Jameson, A; Johnston, S; Kasliwal, M M; Keane, E F; Keller, S; Kocz, J; Kramer, M; Leloudas, G; Malesani, D; Mulchaey, J S; Ng, C; Ofek, E O; Perley, D A; Possenti, A; Schmidt, B P; Shen, Yue; Stappers, B; Tisserand, P; van Straten, W; Wolf, C

    2014-01-01

    Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 14 May, 2014 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm$^{-3}$ pc, giving an upper limit on source redshift of $z \\lesssim 0.5$. FRB 140514 was found to be 21$\\pm$7% (3-$\\sigma$) circularly polarized on the leading edge with a 1-$\\sigma$ upper limit on linear polarization $<10%$. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may...

  20. A relativistic type Ibc supernova without a detected gamma-ray burst.

    Science.gov (United States)

    Soderberg, A M; Chakraborti, S; Pignata, G; Chevalier, R A; Chandra, P; Ray, A; Wieringa, M H; Copete, A; Chaplin, V; Connaughton, V; Barthelmy, S D; Bietenholz, M F; Chugai, N; Stritzinger, M D; Hamuy, M; Fransson, C; Fox, O; Levesque, E M; Grindlay, J E; Challis, P; Foley, R J; Kirshner, R P; Milne, P A; Torres, M A P

    2010-01-28

    Long duration gamma-ray bursts (GRBs) mark the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested in the pulse of gamma-rays and a long-lived radio afterglow. Until now, central-engine-driven supernovae have been discovered exclusively through their gamma-ray emission, yet it is expected that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported.

  1. Hard X-Ray Burst Detected From Caltech Plasma Jet Experiment Magnetic Reconnection Event

    Science.gov (United States)

    Marshall, Ryan S.; Bellan, Paul M.

    2016-10-01

    In the Caltech plasma jet experiment a 100 kA MHD driven jet becomes kink unstable leading to a Rayleigh-Taylor instability that quickly causes a magnetic reconnection event. Movies show that the Rayleigh-Taylor instability is simultaneous with voltage spikes across the electrodes that provide the current that drives the jet. Hard x-rays between 4 keV and 9 keV have now been observed using an x-ray scintillator detector mounted just outside of a kapton window on the vacuum chamber. Preliminary results indicate that the timing of the x-ray burst coincides with a voltage spike on the electrodes occurring in association with the Rayleigh-Taylor event. The x-ray signal accompanies the voltage spike and Rayleigh-Taylor event in approximately 50% of the shots. A possible explanation for why the x-ray signal is sometimes missing is that the magnetic reconnection event may be localized to a specific region of the plasma outside the line of sight of the scintillator. The x-ray signal has also been seen accompanying the voltage spike when no Rayleigh-Taylor is observed. This may be due to the interframe timing on the camera being longer than the very short duration of the Rayleigh-Taylor instability.

  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. Can the bump in the composite spectrum of GRB 910503 be an emission line feature of gamma-ray bursts?

    Institute of Scientific and Technical Information of China (English)

    Yi-Ping Qin; Fu-Wen Zhang

    2005-01-01

    Appearing in the composite spectral data of BATSE, EGRET and COMPTEL for GRB 910503, there is a bump at around 1600keV. We perform a statistical analysis on the spectral data, trying to find out if the bump could be accounted for by a blue-shifted and significantly broadened rest frame line due to the Doppler effect of an expanding fireball surface. We made an F-test and adopted previously proposed criteria. The study reveals that the criteria are well satisfied and the feature can be interpreted as the blue shifted 6.4 keV line. From the fit with this line taken into account, we find the Lorentz factor of this source to be Γ = 116+9-9 (at the 68% confident level,△X2 = 1) and the rest frame spectral peak energy to be EO,p= 2.96+0.24-0.18 keV. Although the existence of the emission line feature requires other independent tests to confirm, the analysis suggests that it is feasible to detect emission line features in the high energy range of GRB spectra when taking into account the Doppler effect of fireball expansion.

  4. Early Detection of Viral Hepatitis Can Save Lives - PSA (:30)

    Centers for Disease Control (CDC) Podcasts

    2010-05-12

    Early detection of viral hepatitis can help prevent liver damage, cirrhosis, and even liver cancer.  Created: 5/12/2010 by Centers for Disease Control and Prevention (CDC).   Date Released: 5/12/2010.

  5. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  6. Design of a confocal microfluidic particle sorter using fluorescent photon burst detection

    NARCIS (Netherlands)

    Kunst, B.H.; Schots, A.; Visser, A.J.W.G.

    2004-01-01

    An instrumental system is described for detecting and sorting single fluorescent particles such as microspheres, bacteria, viruses, or even smaller macromolecules in a flowing liquid. The system consists of microfluidic chips (biochips), computer controlled high voltage power supplies, and a fluores

  7. Detection of a very bright optical flare from a gamma-ray burst at redshift 6.29

    CERN Document Server

    Bo"er, M; Damerdji, Y; Gendre, B; Klotz, A; Stratta, G; Bo\\"{e}r, Michel

    2006-01-01

    The event of September 4th, 2005 (GRB 050904) was detected by the SWIFT/BAT experiment. The source was found to be at a redshift z = 6.29, corresponding to an age of the Universe which is only 7% of the present epoch. The 25 cm TAROT robotic telescope3 was able to catch the bright flare emitted by GRB 050904 at the time of the prompt high-energy event. In this letter we discuss the flux and the behaviour of the optical emission during the prompt high-energy emission and the early afterglow. We combine our data with simultaneous observations performed in X-rays and we analyze the broad-band spectrum. We show that the optical emission is too bright to have the same origin as the high energy photons. Both the temporal and spectral behaviour of the event are difficult to explain within the current internal or reverse shock models. These observations lead us to emphasize the similarity of GRB 050904 with GRB 990123, a remarkable gamma-ray burst whose optical emission reached 9th magnitude4. While GRB 990123 was, u...

  8. An accurate and efficient algorithm for detection of radio bursts with an unknown dispersion measure, for single dish telescopes and interferometers

    CERN Document Server

    Zackay, Barak

    2014-01-01

    Astronomical radio bursts disperse while traveling through the interstellar medium. To optimally detect a short-duration signal within a frequency band, we have to precisely compensate for the pulse dispersion, which is a computationally demanding task. We present the Fast Dispersion Measure Transform (FDMT) algorithm for optimal detection of such signals. Our algorithm has a low theoretical complexity of 2N_f N_t+ N_t N_d log_2(N_f) where N_f, N_t and N_d are the numbers of frequency bins, time bins, and dispersion measure bins, respectively. Unlike previously suggested fast algorithms our algorithm conserves the sensitivity of brute force dedispersion. Our tests indicate that this algorithm, running on a standard desktop computer, and implemented in a high-level programming language, is already faster than the state of the art dedispersion codes running on graphical processing units (GPUs). We also present a variant of the algorithm that can be efficiently implemented on GPUs. The latter algorithm's computa...

  9. Detection of Environmental Trends: What can we control?

    Science.gov (United States)

    Weatherhead, E. C.

    2014-12-01

    Natural variability means that detection of environmental trends often takes a number of years. Weatherhead et al. (1998, 2000, 2001, 2006, 2012) offer estimates for how long detection might take for ozone, ultraviolet radiation, temperature, trace gases. Some methods of observing the environment are more effective and efficient than others. We can control four aspects of our monitoring approach which have direct impact in how well we can monitor trends. We can control the accuracy which can direclty impact how certain we are in final trend results. We can control how often we take measurements; for some parameters, such as trace gases, weekly, monthly or seasonal measurements are prohibited due to logistics or cost. We can control where we measure--including distributions of networks, or satellite footprint size. Finally, we can control what ancillary measurements are taken to determine the attribution of trends to better identify underlying trends. Decisions on these four aspects of monitoring can have direct impact on both trend detection and interpretation of future trends.

  10. Method and apparatus for coherent burst ranging

    Science.gov (United States)

    Wachter, E.A.; Fisher, W.G.

    1998-04-28

    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time. 12 figs.

  11. Burst Suppression: A Review and New Insights

    Directory of Open Access Journals (Sweden)

    Jonathan Dillon Kenny

    2014-12-01

    Full Text Available 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 results of our new study showing clear electrophysiological differences in burst suppression patterns induced by two common general anesthetics, sevoflurane and propofol. Our data suggest that the circuit mechanisms that generate burst suppression activity may differ between different general anesthetics.

  12. FAST TCP over optical burst switched networks: Modeling and stability analysis

    KAUST Repository

    Shihada, Basem

    2013-04-01

    FAST TCP is important for promoting data-intensive applications since it can cleverly react to both packet loss and delay for detecting network congestion. This paper provides a continuous time model and extensive stability analysis of FAST TCP congestion-control mechanism in bufferless Optical Burst Switched Networks (OBS). The paper first shows that random burst contentions are essential to stabilize the network, but cause throughput degradation in FAST TCP flows when a burst with all the packets from a single round is dropped. Second, it shows that FAST TCP is vulnerable to burst delay and fails to detect network congestion due to the little variation of round-trip time, thus unstable. Finally it shows that introducing extra delays by implementing burst retransmission stabilizes FAST TCP over OBS. The paper proves that FAST TCP is not stable over barebone OBS. However, it is locally, exponentially, and asymptotically stable over OBS with burst retransmission.

  13. Air coupled ultrasonic detection of surface defects in food cans

    Science.gov (United States)

    Seco, Fernando; Ramón Jiménez, Antonio; del Castillo, María Dolores

    2006-06-01

    In this paper, we describe an ultrasonic inspection system used for detection of surface defects in food cans. The system operates in the pulse-echo mode and analyses the 220 kHz ultrasonic signal backscattered by the object. The classification of samples into valid or defective is achieved with χ2 statistics and the k nearest neighbour method, applied to features computed from the envelope of the ultrasonic echo. The performance of the system is demonstrated empirically in detection of the presence of the pull tab on the removable lid of easy-open food cans, in a production line. It is found that three factors limit the performance of the classification: the misalignment of the samples, their separation of the ultrasonic transducer, and the vibration of the conveyor belt. When these factors are controlled, classification success rates between 94% and 99% are achieved.

  14. Do alien particles exist, and can they be detected?

    CERN Document Server

    Gasperini, M

    2016-01-01

    We may call "alien particles" those particles belonging to the matter/field content of a $d$-dimensional brane other than the $3$-brane (or stack of branes) sweeping the space-time in which we live. They can appear in our space-time at the regions of intersection between our and their brane. They can be identified (or not) as alien matter depending on their properties, on the physical laws governing their evolution in the "homeland" brane, and on the details of our detection techniques.

  15. Do alien particles exist, and can they be detected?

    Science.gov (United States)

    Gasperini, M.

    2016-07-01

    We may call “alien particles” those particles belonging to the matter/field content of a d-dimensional brane other than the 3-brane (or stack of branes) sweeping the spacetime in which we live. They can appear in our spacetime at the regions of intersection between our and their brane. They can be identified (or not) as alien matter depending on their properties, on the physical laws governing their evolution in the “homeland” brane, and on the details of our detection techniques.

  16. Early Hearing Detection and Intervention: Can Your Baby Hear?

    Centers for Disease Control (CDC) Podcasts

    2007-06-15

    This podcast discusses how important it is that every child receives a hearing screening as soon as possible after birth. It also gives specific ways that parents and health providers can find out if a child has a possible hearing loss and where to get further information. (Created 6/5/2007 by the Early Hearing Detection and Intervention Program, NCBDDD).  Created: 6/15/2007 by National Center on Birth Defects and Developmental Disabilities.   Date Released: 6/25/2007.

  17. Burst analysis tool for developing neuronal networks exhibiting highly varying action potential dynamics

    Directory of Open Access Journals (Sweden)

    Fikret Emre eKapucu

    2012-06-01

    Full Text Available In this paper we propose a firing statistics based neuronal network burst detection algorithm for neuronal networks exhibiting highly variable action potential dynamics. Electrical activity of neuronal networks is generally analyzed by the occurrences of spikes and bursts both in time and space. Commonly accepted analysis tools employ burst detection algorithms based on predefined criteria. However, maturing neuronal networks, such as those originating from human embryonic stem cells (hESC, exhibit highly variable network structure and time-varying dynamics. To explore the developing burst/spike activities of such networks, we propose a burst detection algorithm which utilizes the firing statistics based on interspike interval (ISI histograms. Moreover, the algorithm calculates interspike interval thresholds for burst spikes as well as for pre-burst spikes and burst tails by evaluating the cumulative moving average and skewness of the ISI histogram. Because of the adaptive nature of the proposed algorithm, its analysis power is not limited by the type of neuronal cell network at hand. We demonstrate the functionality of our algorithm with two different types of microelectrode array (MEA data recorded from spontaneously active hESC-derived neuronal cell networks. The same data was also analyzed by two commonly employed burst detection algorithms and the differences in burst detection results are illustrated. The results demonstrate that our method is both adaptive to the firing statistics of the network and yields successful burst detection from the data. In conclusion, the proposed method is a potential tool for analyzing of hESC-derived neuronal cell networks and thus can be utilized in studies aiming to understand the development and functioning of human neuronal networks and as an analysis tool for in vitro drug screening and neurotoxicity assays.

  18. Burst analysis tool for developing neuronal networks exhibiting highly varying action potential dynamics.

    Science.gov (United States)

    Kapucu, Fikret E; Tanskanen, Jarno M A; Mikkonen, Jarno E; Ylä-Outinen, Laura; Narkilahti, Susanna; Hyttinen, Jari A K

    2012-01-01

    In this paper we propose a firing statistics based neuronal network burst detection algorithm for neuronal networks exhibiting highly variable action potential dynamics. Electrical activity of neuronal networks is generally analyzed by the occurrences of spikes and bursts both in time and space. Commonly accepted analysis tools employ burst detection algorithms based on predefined criteria. However, maturing neuronal networks, such as those originating from human embryonic stem cells (hESCs), exhibit highly variable network structure and time-varying dynamics. To explore the developing burst/spike activities of such networks, we propose a burst detection algorithm which utilizes the firing statistics based on interspike interval (ISI) histograms. Moreover, the algorithm calculates ISI thresholds for burst spikes as well as for pre-burst spikes and burst tails by evaluating the cumulative moving average (CMA) and skewness of the ISI histogram. Because of the adaptive nature of the proposed algorithm, its analysis power is not limited by the type of neuronal cell network at hand. We demonstrate the functionality of our algorithm with two different types of microelectrode array (MEA) data recorded from spontaneously active hESC-derived neuronal cell networks. The same data was also analyzed by two commonly employed burst detection algorithms and the differences in burst detection results are illustrated. The results demonstrate that our method is both adaptive to the firing statistics of the network and yields successful burst detection from the data. In conclusion, the proposed method is a potential tool for analyzing of hESC-derived neuronal cell networks and thus can be utilized in studies aiming to understand the development and functioning of human neuronal networks and as an analysis tool for in vitro drug screening and neurotoxicity assays.

  19. Can JWST Follow Up on Gravitational-Wave Detections?

    Science.gov (United States)

    Kohler, Susanna

    2016-02-01

    Bitten by the gravitational-wave bug? While we await Thursdays press conference, heres some food for thought: if LIGO were able to detect gravitational waves from compact-object mergers, how could we follow up on the detections? A new study investigates whether the upcoming James Webb Space Telescope (JWST) will be able to observe electromagnetic signatures of some compact-object mergers.Hunting for MergersStudying compact-object mergers (mergers of black holes and neutron stars) can help us understand a wealth of subjects, like high-energy physics, how matter behaves at nuclear densities, how stars evolve, and how heavy elements in the universe were created.The Laser Interferometer Gravitational-Wave Observatory (LIGO) is searching for the signature ripples in spacetime identifying these mergers, but gravitational waves are squirrelly: LIGO will only be able to localize wave sources to tens of square degrees. If we want to find out more about any mergers LIGO discovers in gravitational waves, well need a follow-up search for electromagnetic counterparts with other observatories.The Kilonova KeyOne possible electromagnetic counterpart is kilonovae, explosions that can be produced during a merger of a binary neutron star or a neutron starblack hole system. If the neutron star is disrupted during the merger, some of the hot mass is flung outward and shines brightly by radioactive decay.Kilonovae are especially promising as electromagnetic counterparts to gravitational waves for three reasons:They emit isotropically, so the number of observable mergers isnt limited by relativistic beaming.They shine for a week, giving follow-up observatories time to search for them.The source location can beeasily recovered.The only problem? We dont currently have any sensitive survey instruments in the near-infrared band (where kilonova emission peaks) that can provide coverage over tens of square degrees. Luckily, we will soon have just the thing: JWST, launching in 2018!JWSTs

  20. Can a safeguards accountancy system really detect an unauthorized removal

    Energy Technology Data Exchange (ETDEWEB)

    Ehinger, M.H.; Ellis, J.H.

    1981-11-01

    Theoretical investigations and system studies indicate safeguards material balance data from reprocessing plants can be used to detect unauthorized removals. Plant systems have been modeled and simulated data used to demonstrate the techniques. But how sensitive are the techniques when used with actual plant data. What is the effect of safeguards applications on plant operability. Can safeguards be acceptable to plant operators, and are there any benefits to be derived. The Barnwell Nuclear Fuel Plant (BNFP) has been devoted to answering these and other questions over the past several years. A computerized system of near-real-time accounting and in-process inventory has been implemented and demonstrated during actual plant test runs. Measured inventories and hourly material balance closures have been made to assess safeguards in an operating plant application. The tests have culminated in actual removals of material from the operating plant to investigate the response and measure the sensitivity of the safeguards and data evaluation system.

  1. Broadband Spectral Study of Magnetar Bursts

    Science.gov (United States)

    Kirmizibayrak, Demet; Gogus, Ersin; Sasmaz Mus, Sinem; Kaneko, Yuki

    2016-07-01

    Magnetar bursts occur sporadically on random occasions, and every burst-active episode carries unique information about the bursting magnetar. Therefore, in-depth spectral and temporal analyses of each of the magnetar bursts provide new insights into the bursting and radiation mechanisms. There have been a number of studies over the last decade, investigating the spectral and temporal properties of magnetar bursts. The spectra of typical magnetar bursts were generally described with the Comptonized model or the sum of two blackbody functions. However, it was recently shown that the actual spectral nature of these bursts can be conclusively determined if the spectral analysis is performed on a wide energy coverage. We present the results of in-depth systematic broadband (2 - 250 keV) spectral analysis of a large number of bursts originated from three magnetars: SGR 1806-20, SGR 1900+14, and SGR J1550-5418, observed with the Rossi X-ray Timing Explorer.

  2. 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

  3. The Five Year Fermi/GBM Magnetar Burst Catalog

    NARCIS (Netherlands)

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

    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

  4. Can accelerometers detect mass variations in Amazonian trees?

    Science.gov (United States)

    van Emmerik, Tim; Steele-Dunne, Susan; Gentine, Pierre; Guerin, Marceau; Hut, Rolf; Oliveira, Rafael; van de Giesen, Nick

    2016-04-01

    The mass of trees is influenced by physiological processes within the tree (e.g. transpiration and root water uptake), as well as external loads (e.g. intercepted precipitation). Recent studies have found diurnal variations in radar backscatter over vegetated areas, which might be attributed to mass changes of the vegetation layer. Field measurements are required to study the driving processes. This study aims to use measured three-dimensional displacement and acceleration of trees, to detect and quantify their diurnal (bio)mass variations. Accelerometers and dendrometers were installed on seven different tree species in the Amazon rainforest. Trees were selected to cover a broad range of wood density. Using spectral analysis, the governing frequencies in the acceleration time series were found. The governing frequencies showed a diurnal pattern, as well as a change during precipitation events. Our results suggest that we can separate and potentially quantify tree mass changes due to (1) internal water redistribution and (2) intercepted precipitation. This will allow further investigation of the effect of precipitation and water stress on tree dynamics in forest canopies.

  5. Millisecond extragalactic radio bursts as magnetar flares

    CERN Document Server

    Popov, S B

    2013-01-01

    Properties of the population of millisecond extragalactic radio bursts discovered by Thornton et al. (2013) are in good correspondence with the hypothesis that such events are related to hyperflares of magnetars, as was proposed by us after the first observation of an extragalactic millisecond radio burst by Lorimer et al. (2007). We also point that some of multiple millisecond radio bursts from M31 discovered by Rubio-Herrera et al. (2013) also can be related to weaker magnetar bursts.

  6. GRB 091208B: FIRST DETECTION OF THE OPTICAL POLARIZATION IN EARLY FORWARD SHOCK EMISSION OF A GAMMA-RAY BURST AFTERGLOW

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, T.; Chiyonobu, S.; Fukazawa, Y.; Ikejiri, Y.; Itoh, R.; Komatsu, T.; Miyamoto, H.; Nagae, O.; Sakimoto, K.; Sasada, M.; Tanaka, H.; Yamanaka, M. [Department of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan); Toma, K. [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan); Kawabata, K. S.; Mizuno, T.; Ohsugi, T.; Uemura, M. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Inoue, T.; Yamashita, T. [Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku, Sagamihara 252-5258 (Japan); Nakaya, H., E-mail: uehara@hep01.hepl.hiroshima-u.ac.jp [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); and others

    2012-06-10

    We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149-706 s after the burst trigger, and the polarization degree is P = 10.4( {+-} 2.5%. The optical light curve at this time shows a power-law decay with index -0.75 {+-} 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by Steele et al.). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as those amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

  7. Fast and slow frequency-drifting millisecond bursts in Jovian decametric radio emissions

    Science.gov (United States)

    Ryabov, V. B.; Zarka, P.; Hess, S.; Konovalenko, A.; Litvinenko, G.; Zakharenko, V.; Shevchenko, V. A.; Cecconi, B.

    2014-08-01

    We present an analysis of several Jovian Io-related decametric radio storms recorded in 2004-2012 at the Ukrainian array UTR-2 using the new generation of baseband digital receivers. Continuous baseband sampling within sessions lasting for several hours enabled us to study the evolution of multiscale spectral patterns during the whole storm at varying time and frequency resolutions and trace the temporal transformation of burst structures in unprecedented detail. In addition to the well-known frequency drifting millisecond patterns known as S bursts we detected two other classes of events that often look like S bursts at low resolution but reveal a more complicated structure in high resolution dynamic spectra. The emissions of the first type (LS bursts, superposition of L and S type emissions) have a much lower frequency drift rate than the usual quasi linearly drifting S bursts (QS) and often occur within a frequency band where L emission is simultaneously present, suggesting that both LS and at least part of L emissions may come from the same source. The bursts of the second type (modulated S bursts called MS) are formed by a wideband frequency-modulated envelope that can mimic S bursts with very steep negative (or even positive) drift rates. Observed with insufficient time-frequency resolution, MS look like S bursts with complex shapes and varying drifts; MS patterns often occur in association with (i) narrowband emission; (ii) S burst trains; or (iii) sequences of fast drift shadow events. We propose a phenomenological description for various types of S emissions, that should include at least three components: high- and low-frequency limitation of the overall frequency band of the emission, fast frequency modulation of emission structures within this band, and emergence of elementary S burst substructures, that we call "forking" structures. All together, these three components can produce most of the observed spectral structures, including S bursts with

  8. Powerful Radio Burst Indicates New Astronomical Phenomenon

    Science.gov (United States)

    2007-09-01

    . "It was a bit of luck that the survey included some observations of the sky surrounding the clouds," Narkevic said. It was from those "flanking" observations that the mysterious radio burst appeared in the data. The burst of radio waves was strong by astronomical standards, but lasted less than five milliseconds. The signal was spread out, with higher frequencies arriving at the telescope before the lower frequencies. This effect, called dispersion, is caused by the signal passing through ionized gas in interstellar and intergalactic space. The amount of this dispersion, the astronomers said, indicates that the signal likely originated about three billion light-years from Earth. No previously-detected cosmic radio burst has the same set of characteristics. "This burst represents an entirely new astronomical phenomenon," Bailes said. The astronomers estimate on the basis of their results that hundreds of similar events should occur over the sky each day. "Few radio surveys have the necessary sensitivity to such short-duration bursts, which makes them notoriously difficult to detect with current instruments," added Crawford. The next generation of radio telescopes currently under development should be able to detect many of these bursts across the sky. Although the nature of the mysterious new object is unclear, the astronomers have some ideas of what may cause such a burst. One idea is that it may be part of the energy released when a pair of superdense neutron stars collide and merge. Such an event is thought by some scientists to be the cause of one type of gamma-ray burst, but the only radio emission seen so far from these has been from the long-lived "afterglow" that follows the original burst. Another, more exotic, candidate is a burst of energy from an evaporating black hole. Black holes, concentrations of mass so dense that not even light can escape their powerful gravity, can lose mass and energy through a process proposed by famed British physicist Stephen

  9. Can Hyperspectral Remote Sensing Detect Species Specific Biochemicals ?

    Science.gov (United States)

    Vanderbilt, V. C.; Daughtry, C. S.

    2011-12-01

    Discrimination of a few plants scattered among many plants is a goal common to detection of agricultural weeds, invasive plant species and illegal Cannabis clandestinely grown outdoors, the subject of this research. Remote sensing technology provides an automated, computer based, land cover classification capability that holds promise for improving upon the existing approaches to Cannabis detection. In this research, we investigated whether hyperspectral reflectance of recently harvested, fully turgid Cannabis leaves and buds depends upon the concentration of the psychoactive ingredient Tetrahydrocannabinol (THC) that, if present at sufficient concentration, presumably would allow species-specific identification of Cannabis.

  10. The Double Firing Burst

    Science.gov (United States)

    2008-09-01

    this nearly head-on alignment to occur is only about once a decade," added his colleague Cristiano Guidorzi. GRB 080319B was detected by the NASA/STFC/ASI Swift satellite towards the constellation of Boötes, the "Herdsman". A host of ground-based telescopes reacted promptly to study this new object in the sky, including ESO's Very Large Telescope, which was the first to provide the distance of the object, 7.5 billion light-years. The visible light from the burst was detected by a handful of wide-field cameras worldwide that are mounted on telescopes constantly monitoring a large fraction of the sky. One of these was the TORTORA camera mounted on the 0.6-m REM telescope at ESO's La Silla Observatory (ESO 26/07). TORTORA's rapid imaging provides the most detailed look yet at the visible light associated with the initial blast of a gamma-ray burst. "We've been waiting a long time for this one," says TORTORA senior scientist Grigory Beskin of Russia's Special Astrophysical Observatory. The data collected simultaneously by TORTORA and the Swift satellite allowed astronomers to explain the properties of this burst.

  11. Compton scattering in terrestrial gamma-ray flashes detected with the Fermi gamma-ray burst monitor

    CERN Document Server

    Fitzpatrick, Gerard; McBreen, Sheila; Briggs, Michael S; Foley, Suzanne; Tierney, David; Chaplin, Vandiver L; Connaughton, Valerie; Stanbro, Matthew; Xiong, Shaolin; Dwyer, Joseph; Fishman, Gerald J; Roberts, Oliver J; von Kienlin, Andreas

    2015-01-01

    Terrestrial gamma-ray flashes (TGFs) are short intense flashes of gamma rays associated with lightning activity in thunderstorms. Using Monte Carlo simulations of the relativistic runaway electron avalanche (RREA) process, theoretical predictions for the temporal and spectral evolution of TGFs are compared to observations made with the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Assuming a single source altitude of 15 km, a comparison of simulations to data is performed for a range of empirically chosen source electron variation time scales. The data exhibit a clear softening with increased source distance, in qualitative agreement with theoretical predictions. The simulated spectra follow this trend in the data, but tend to underestimate the observed hardness. Such a discrepancy may imply that the basic RREA model is not sufficient. Alternatively, a TGF beam that is tilted with respect to the zenith could produce an evolution with source distance that is compatible with the da...

  12. Readout of the UFFO Slewing Mirror Telescope to detect UV/optical photons from Gamma-Ray Bursts

    DEFF Research Database (Denmark)

    Kim, J. E.; Lim, H.; Nam, J. W.

    2013-01-01

    The Slewing Mirror Telescope (SMT) was proposed for rapid response to prompt UV/optical photons from Gamma-Ray Bursts (GRBs). The SMT is a key component of the Ultra-Fast Flash Observatory (UFFO)-pathfinder, which will be launched aboard the Lomonosov spacecraft at the end of 2013. The SMT utilizes...... plane detector of Intensified Charge-Coupled Device (ICCD). The ICCD is sensitive to UV/optical photons of 200–650 nm in wavelength by using a UV-enhanced S20 photocathode and amplifies photoelectrons at a gain of 104–106 in double Micro-Channel Plates. These photons are read out by a Kodak KAI-0340...

  13. [Scoring system for early detection of critical illness can fail].

    Science.gov (United States)

    Kamstrup Christiansen, Lærke; Andreasen, Jo Bønding; Frederiksen, Christian Alcaraz; Juhl-Olsen, Peter; Sloth, Erik

    2013-02-18

    A 57-year old male underwent elective aortic valve replacement. The immediate post-operative course was uneventful and the patient was discharged with the lowest possible score on a newly implemented scale for early detection of critical illness. The following day he was readmitted with dyspnoea. The critical illness score was still low despite ultrasonic demonstration of a large pericardial effusion requiring drainage. We are concerned that the widely adopted critical illness scale is not sufficiently sensitive for cardiac surgery patients and advocate the use of point-of-care ultrasound.

  14. Research on experiment and calculation of foam bursting device

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This research presents experimental data on mechanical foam bursting device, based on the high speed of air fluid impinging insidethe foam bursting device, foam bubbles disrupted as a consequence of pressures changed very quickly as shear force and their impact forces. Experimental data on foam-bursting capacity have been presented. Designed device can provide effective foam bursting on collapse foam.

  15. On the connection of gamma-ray bursts and X-ray flashes in the BATSE and RHESSI databases

    Science.gov (United States)

    Řípa, J.; Mészáros, A.

    2016-12-01

    Classification of gamma-ray bursts (GRBs) into groups has been intensively studied by various statistical tests in previous years. It has been suggested that there was a distinct group of GRBs, beyond the long and short ones, with intermediate durations. However, such a group is not securely confirmed yet. Strangely, concerning the spectral hardness, the observations from the Swift and RHESSI satellites give different results. For the Swift/BAT database it is found that the intermediate-duration bursts might well be related to so-called X-ray flashes (XRFs). On the other hand, for the RHESSI dataset the intermediate-duration bursts seem to be spectrally too hard to be given by XRFs. The connection of the intermediate-duration bursts and XRFs for the BATSE database is not clear as well. The purpose of this article is to check the relation between XRFs and GRBs for the BATSE and RHESSI databases, respectively. We use an empirical definition of XRFs introduced by other authors earlier. For the RHESSI database we also use a transformation between the detected counts and the fluences based on the simulated detector response function. The purpose is to compare the hardnesses of GRBs with the definition of XRFs. There is a 1.3-4.2 % fraction of XRFs in the whole BATSE database. The vast majority of the BATSE short bursts are not XRFs because only 0.7-5.7 % of the short bursts can be given by XRFs. However, there is a large uncertainty in the fraction of XRFs among the intermediate-duration bursts. The fraction of 1-85 % of the BATSE intermediate-duration bursts can be related to XRFs. For the long bursts this fraction is between 1.0 % and 3.4 %. The uncertainties in these fractions are large, however it can be claimed that all BATSE intermediate-duration bursts cannot be given by XRFs. At least 79 % of RHESSI short bursts, at least 53 % of RHESSI intermediate-duration bursts, and at least 45 % of RHESSI long bursts should not be given by XRFs. A simulation of XRFs

  16. V/V(max) test applied to SMM gamma-ray bursts

    Science.gov (United States)

    Matz, S. M.; Higdon, J. C.; Share, G. H.; Messina, D. C.; Iadicicco, A.

    1992-01-01

    We have applied the V/V(max) test to candidate gamma-ray bursts detected by the Gamma-Ray Spectrometer (GRS) aboard the SMM satellite to examine quantitatively the uniformity of the burst source population. For a sample of 132 candidate bursts identified in the GRS data by an automated search using a single uniform trigger criterion we find average V/V(max) = 0.40 +/- 0.025. This value is significantly different from 0.5, the average for a uniform distribution in space of the parent population of burst sources; however, the shape of the observed distribution of V/V(max) is unusual and our result conflicts with previous measurements. For these reasons we can currently draw no firm conclusion about the distribution of burst sources.

  17. Species determination - can we detect and quantify meat adulteration?

    DEFF Research Database (Denmark)

    Ballin, Nicolai Zederkopff; Vogensen, Finn Kvist; Karlsson, Anders H

    2009-01-01

    Proper labelling of meat products is important to help fair-trade, and to enable consumers to make informed choices. However, it has been shown that labelling of species, expressed as weight/weight (w/w), on meat product labels was incorrect in more than 20% of cases. Enforcement of labelling...... regulations requires reliable analytical methods. Analytical methods are often based on protein or DNA measurements, which are not directly comparable to labelled meat expressed as w/w. This review discusses a wide range of analytical methods with focus on their ability to quantify and their limits...... of detection (LOD). In particular, problems associated with a correlation from quantitative DNA based results to meat content (w/w) are discussed. The hope is to make researchers aware of the problems of expressing DNA results as meat content (w/w) in order to find better alternatives. One alternative...

  18. High Redshift Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil

    2012-01-01

    The Swift Observatory has been detecting 100 gamma-ray bursts per year for 7 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from 1 minute after the burst, continuing for days. GRBs are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=9.4 giving information on metallicity, star formation rate and reionization. The talk will present the latest results.

  19. Detection of QTL for Cold Tolerance at Bud Bursting Stage Using Chromosome Segment Substitution Lines in Rice (Oryza sativa)

    Institute of Scientific and Technical Information of China (English)

    LIN Jing; WANG Yan-ping; WANG Cai-lin; ZHU Wen-yin; ZHANG Ya-dong; ZHU Zhen; ZHAO Ling; CHEN Tao; ZHAO Qing-yong; ZHOU Li-hui; FANG Xian-wen

    2011-01-01

    The cold tolerance at the bud bursting stage (CTB) was evaluated at 5℃ by using a set of 95 chromosome segment substitution lines (CSSLs) derived from an indica rice 9311 and a japonica rice Nipponbare with a genetic background of 9311.The result showed that six CSSLs had slightly stronger effect on CTB than 9311.Total four quantitative trait loci (QTLs) for CTB were preliminary mapped on chromosomes 5 and 7 by substitution mapping.qCTB-5-1,qCTB-5-2 and qCTB-5-3 were mapped in the region of RM267-RM1237,RM2422-RM6054 and RM3321-RM1054,which were 21.3 cM,27.4 cM and 12.7 cM in genetic distance on rice chromosome 5,respectively.qCTB-7 was mapped in a 6.8-cM region of RM11-RM2752 on rice chromosome 7.

  20. Pulse properties of terrestrial gamma-ray flashes detected by the Fermi Gamma-Ray Burst Monitor

    CERN Document Server

    Foley, Suzanne; Briggs, Michael S; Connaughton, Valerie; Tierney, David; McBreen, Sheila; Dwyer, Joseph; Chaplin, Vandiver L; Bhat, P Narayana; Byrne, David; Cramer, Eric; Fishman, Gerald J; Xiong, Shaolin; Greiner, Jochen; Kippen, R Marc; Meegan, Charles A; Paciesas, William S; Preece, Robert D; von Kienlin, Andreas; Wilson-Hodge, Colleen

    2015-01-01

    The Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope has triggered on over 300 terrestrial gamma-ray flashes (TGFs) since its launch in June 2008. With 14 detectors, GBM collects on average ~100 counts per triggered TGF, enabling unprecedented studies of the time profiles of TGFs. Here we present the first rigorous analysis of the temporal properties of a large sample of TGFs (278), including the distributions of the rise and fall times of the individual pulses and their durations. A variety of time profiles are observed with 19 of TGFs having multiple pulses separated in time and 31 clear cases of partially overlapping pulses. The effect of instrumental dead time and pulse pileup on the temporal properties are also presented. As the observed gamma ray pulse structure is representative of the electron flux at the source, TGF pulse parameters are critical to distinguish between relativistic feedback discharge and lightning leader models. We show that at least 67% of TGFs at satellite ...

  1. Burst Detector X-Ray IIR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The Burst Detector X-Ray (BDX) instrument for the Block IIR series of Global Positioning System satellites is described. The BDX instrument can locate and characterize exoatmospheric nuclear detonations by using four sensors consisting of sets of filters over silicon diodes to detect x rays of various energies from the burst. On the BDX-IIR, a fifth sensor with a response spanning those of the other sensors confirms coincidences among the four main channels. The mechanical and electronic features of the BDX-IIR and its sensors are described. The calibrations and the system tests used in flight are presented. The commands for the BDX-IIR are given. The messages sent from the BDX-IIR are described in detail.

  2. Bipolar Transistors Can Detect Charge in Electrostatic Experiments

    Science.gov (United States)

    Dvorak, L.

    2012-01-01

    A simple charge indicator with bipolar transistors is described that can be used in various electrostatic experiments. Its behaviour enables us to elucidate links between 'static electricity' and electric currents. In addition it allows us to relate the sign of static charges to the sign of the terminals of an ordinary battery. (Contains 7 figures…

  3. Immunosignaturing can detect products from molecular markers in brain cancer.

    Directory of Open Access Journals (Sweden)

    Alexa K Hughes

    Full Text Available Immunosignaturing shows promise as a general approach to diagnosis. It has been shown to detect immunological signs of infection early during the course of disease and to distinguish Alzheimer's disease from healthy controls. Here we test whether immunosignatures correspond to clinical classifications of disease using samples from people with brain tumors. Blood samples from patients undergoing craniotomies for therapeutically naïve brain tumors with diagnoses of astrocytoma (23 samples, Glioblastoma multiforme (22 samples, mixed oligodendroglioma/astrocytoma (16 samples, oligodendroglioma (18 samples, and 34 otherwise healthy controls were tested by immunosignature. Because samples were taken prior to adjuvant therapy, they are unlikely to be perturbed by non-cancer related affects. The immunosignaturing platform distinguished not only brain cancer from controls, but also pathologically important features about the tumor including type, grade, and the presence or absence of O(6-methyl-guanine-DNA methyltransferase methylation promoter (MGMT, an important biomarker that predicts response to temozolomide in Glioblastoma multiformae patients.

  4. DO THE FERMI GAMMA-RAY BURST MONITOR AND SWIFT BURST ALERT TELESCOPE SEE THE SAME SHORT GAMMA-RAY BURSTS?

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Eric; Briggs, Michael S. [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Connaughton, Valerie [Universities Space Research Association, Science and Technology Institute, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Lien, Amy [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Goldstein, Adam [NASA Postdoctoral Program, Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pelassa, Veronique [Smithsonian Astrophysical Observatory, P.O. Box 97, Amado, AZ 85645 (United States); Troja, Eleonora, E-mail: eb0016@uah.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-02-20

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  5. Implementation of Frequency Drift for Identification of Solar Radio Burst Type II

    Directory of Open Access Journals (Sweden)

    Nur Zulaikha Mohd Afandi

    2016-10-01

    Full Text Available Sun is constantly produced mass and radiation during its natural activities, which will interact with ionosphere and affect the earth weather. In radio astronomer community, CALLISTO is used to capture the radio signal comes from solar activities such as solar burst. Solar flares and Coronal Mass Ejections (CMEs were closely associated with the production of solar radio burst Type II and III. However, the determination of solar burst existence is done manually using spectrograph which appears for every 15 minutes.  In order to assist the solar radio researcher to speed up the process of solar burst identification and detection, this work presents a new algorithm to auto classify solar radio burst Type II and III. The value of frequency drift was used as the main idea in this auto classify algorithm because it can easily implemented using MATLAB. There are three main steps involved named as pre-processing, identification and classification. Auto calculation of frequency drift burst on spectra was obtained from two parts which are frequency axis (df and time axis (dt. The results of the frequency drift implementation in classification algorithm show that the algorithm developed gave almost similar determination as in manual detection. However, there are always have rooms for improvement for better detection system in future which may include specific characterization of bursts and improved noise elimination.

  6. High-Energy Spectral Signatures in $\\gamma$-Ray Bursts

    CERN Document Server

    Baring, M G

    1999-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several Gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  7. Two classes of gamma-ray bursts

    CERN Document Server

    Katz, J I

    1995-01-01

    Data from the 3B Catalogue suggest that short and long GRB are the results of different classes of events, rather than different parameter values within a single class: Short bursts have harder spectra in the BATSE bands, but chiefly long bursts are detected at photon energies over 1 MeV, implying that their hard photons are radiated by a process not found in short bursts. The values of \\langle V/V_{max} \\rangle for short and long bursts differ by 4.3 \\sigma, implying different spatial distributions. Only the soft gamma-ray radiation mechanisms are the same in both classes.

  8. Stirling Colgate and Gamma-Ray Bursts

    Science.gov (United States)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  9. How can the Odderon be detected at RHIC and LHC

    CERN Document Server

    Avila, R; Nicolescu, B; Avila, Regina; Gauron, Pierre; Nicolescu, Basarab

    2007-01-01

    The Odderon remains an elusive object, 33 years after its invention. The Odderon is now a fundamental object in QCD and CGC and it has to be found experimentally if QCD and CGC are right. In the present paper, we show how to find it at RHIC and LHC. The most spectacular signature of the Odderon is the predicted difference between the differential cross-sections for proton-proton and antiproton-proton at high s and moderate t. The experiment can be done by using the STAR detector at RHIC and by combining these future data with the already present UA4/2 data. The Odderon could also be found by ATLAS exeperiment at LHC by performing a high-precision measurement of the real part of the hadron elastic scattering amplitude at small t.

  10. Expectations for Joint Gravitational Wave-Electromagnetic Detections with Advanced LIGO/Virgo and the Fermi Gamma Ray Burst Monitor

    Science.gov (United States)

    Burns, E.; Connaughton, V.; Briggs, M. S.; Goldstein, A.; Hamburg, R.; Littenberg, T.

    2016-10-01

    We estimate the fraction of GBM detected short GRBs that should be detectable by Advanced LIGO/Virgo. We also look at the fraction of GW localizations that should be visible to GBM, as well as area reduction by using joint localizations.

  11. Amplitude-Modulated Bursting: A Novel Class of Bursting Rhythms

    Science.gov (United States)

    Vo, Theodore; Kramer, Mark A.; Kaper, Tasso J.

    2016-12-01

    We report on the discovery of a novel class of bursting rhythms, called amplitude-modulated bursting (AMB), in a model for intracellular calcium dynamics. We find that these rhythms are robust and exist on open parameter sets. We develop a new mathematical framework with broad applicability to detect, classify, and rigorously analyze AMB. Here we illustrate this framework in the context of AMB in a model of intracellular calcium dynamics. In the process, we discover a novel family of singularities, called toral folded singularities, which are the organizing centers for the amplitude modulation and exist generically in slow-fast systems with two or more slow variables.

  12. 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.

  13. Unveiling the population of orphan Gamma Ray Bursts

    CERN Document Server

    Ghirlanda, G; Campana, S; Vergani, S D; Japelj, J; Bernardini, M G; Burlon, D; D'Avanzo, P; Melandri, A; Gomboc, A; Nappo, F; Paladini, R; Pescalli, A; Salafia, O S; Tagliaferri, G

    2015-01-01

    Gamma Ray Bursts are detectable in the gamma-ray band if their jets are oriented towards the observer. However, for each GRB with a typical theta_jet, there should be ~2/theta_jet^2 bursts whose emission cone is oriented elsewhere in space. These off-axis bursts can be eventually detected when, due to the deceleration of their relativistic jets, the beaming angle becomes comparable to the viewing angle. Orphan Afterglows (OA) should outnumber the current population of bursts detected in the gamma-ray band even if they have not been conclusively observed so far at any frequency. We compute the expected flux of the population of orphan afterglows in the mm, optical and X-ray bands through a population synthesis code of GRBs and the standard afterglow emission model. We estimate the detection rate of OA by on-going and forthcoming surveys. The average duration of OA as transients above a given limiting flux is derived and described with analytical expressions: in general OA should appear as daily transients in o...

  14. Assessing the reliability of eBURST using simulated populations with known ancestry

    Directory of Open Access Journals (Sweden)

    Connor Thomas R

    2007-04-01

    Full Text Available Abstract Background The program eBURST uses multilocus sequence typing data to divide bacterial populations into groups of closely related strains (clonal complexes, predicts the founding genotype of each group, and displays the patterns of recent evolutionary descent of all other strains in the group from the founder. The reliability of eBURST was evaluated using populations simulated with different levels of recombination in which the ancestry of all strains was known. Results For strictly clonal simulations, where all allelic change is due to point mutation, the groups of related strains identified by eBURST were very similar to those expected from the true ancestry and most of the true ancestor-descendant relationships (90–98% were identified by eBURST. Populations simulated with low or moderate levels of recombination showed similarly high performance but the reliability of eBURST declined with increasing recombination to mutation ratio. Populations simulated under a high recombination to mutation ratio were dominated by a single large straggly eBURST group, which resulted from the incorrect linking of unrelated groups of strains into the same eBURST group. The reliability of the ancestor-descendant links in eBURST diagrams was related to the proportion of strains in the largest eBURST group, which provides a useful guide to when eBURST is likely to be unreliable. Conclusion Examination of eBURST groups within populations of a range of bacterial species showed that most were within the range in which eBURST is reliable, and only a small number (e.g. Burkholderia pseudomallei and Enterococcus faecium appeared to have such high rates of recombination that eBURST is likely to be unreliable. The study also demonstrates how three simple tests in eBURST v3 can be used to detect unreliable eBURST performance and recognise populations in which there appears to be a high rate of recombination relative to mutation.

  15. NuSTAR observations of X-ray bursts from the magnetar 1E 1048.1–5937

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongjun; Kaspi, Victoria M.; Archibald, Robert F. [Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada); Beloborodov, Andrei M.; Gotthelf, Eric V.; Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Kouveliotou, Chryssa [Space Science Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Grefenstette, Brian W.; Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-20

    We report the detection of eight bright X-ray bursts from the 6.5 s magnetar 1E 1048.1–5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array. We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT ∼ 6-8 keV in the T{sub 90} duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a ∼13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer. We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B ∼ 2 × 10{sup 15} G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation.

  16. NuSTAR Observations of X-Ray Bursts from the Magnetar 1E 1048.1-5937

    Science.gov (United States)

    An, Hongjun; Kaspi, Victoria M.; Beloborodov, Andrei M.; Kouveliotou, Chryssa; Archibald, Robert T.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Stern, Daniel; Zhang, William W.

    2014-01-01

    We report the detection of eight bright X-ray bursts from the 6.5 s magnetar 1E 1048.1-5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array. We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT is approx. 6-8 keV in the T90 duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a is approx. 13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer.We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B is approx. 2×10(exp15) G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation.

  17. Gamma-ray burst models.

    Science.gov (United States)

    King, Andrew

    2007-05-15

    I consider various possibilities for making gamma-ray bursts, particularly from close binaries. In addition to the much-studied neutron star+neutron star and black hole+neutron star cases usually considered good candidates for short-duration bursts, there are also other possibilities. In particular, neutron star+massive white dwarf has several desirable features. These systems are likely to produce long-duration gamma-ray bursts (GRBs), in some cases definitely without an accompanying supernova, as observed recently. This class of burst would have a strong correlation with star formation and occur close to the host galaxy. However, rare members of the class need not be near star-forming regions and could have any type of host galaxy. Thus, a long-duration burst far from any star-forming region would also be a signature of this class. Estimates based on the existence of a known progenitor suggest that this type of GRB may be quite common, in agreement with the fact that the absence of a supernova can only be established in nearby bursts.

  18. Coupling and noise induced spiking-bursting transition in a parabolic bursting model.

    Science.gov (United States)

    Ji, Lin; Zhang, Jia; Lang, Xiufeng; Zhang, Xiuhui

    2013-03-01

    The transition from tonic spiking to bursting is an important dynamic process that carry physiologically relevant information. In this work, coupling and noise induced spiking-bursting transition is investigated in a parabolic bursting model with specific discussion on their cooperation effects. Fast/slow analysis shows that weak coupling may help to induce the bursting by changing the geometric property of the fast subsystem so that the original unstable periodical solution are stabilized. It turned out that noise can play the similar stabilization role and induce bursting at appropriate moderate intensity. However, their cooperation may either strengthen or weaken the overall effect depending on the choice of noise level.

  19. A Limited Deflection Routing Algorithm Based on Burst Loss Threshold in OBS Networks

    Institute of Scientific and Technical Information of China (English)

    WANG Ru-yan; LONG Ke-ping; WU Wei; YANG Xiao-long; ZHU Wei-le

    2005-01-01

    The deflection routing protocol is an effective contention resolution in Optical Burst Switching network. However, it can worsen loss performance of non-deflected burst on the deflection route. To improve the burst loss performance, a limited deflection routing scheme based on burst loss threshold is proposed to prevent injudicious deflection routing. By using threshold check function, it restrainedly allows the deflected burst to preemptive network resource, consequently, improve the QoS performance of non-deflected burst. Simulation results show that the scheme can efficiently prevent deflected burst contending with non-deflected burst on deflection route, and effectively improve the burst loss performance of entire networks.

  20. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

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

  1. 非协同突发信号的检测与解调%Detection and Demodulation of Burst Signal for Non-cooperative Communication

    Institute of Scientific and Technical Information of China (English)

    魏宇培; 梁先明; 廖龙灵

    2015-01-01

    According to the waveform protocol and frame structure of the Third Generation Maritime Satellite Communication,energy detection is combined with matching filter to realize burst signal detection,then fre-quency estimation and phase estimation is performed according to the result of signals detection. And then signal demodulation is realized through combining initialization phase estimation with phase locked loop ( PLL) . Both theoretical deduction and simulation indicate the method adapts to lower signal-to-noise ratio ( SNR) , higher frequency offset and bigger dynamic range. Signal detection probability approaches to 100 percent,and the demodulation bit error rate(BER) is under 2í10-3 when the Eb/N0 is above 10 dB.%根据典型的海事三代卫星通信帧格式,首先采用能量检测算法结合匹配滤波法进行有效的突发信号的检测,然后根据信号检测的结果进行了突发信号的频率估计和初相估计,再采用初相注入结合锁相环的方式实现突发信号的解调。理论推导和计算仿真表明,该方法能够适应较低信噪比、较大频偏和起伏动态的影响,当信噪比大于10 dB时,信号检测概率基本达到100%,解调误码率低于2×10-3。

  2. The Broad-Lined Type Ic SN 2012ap and the Nature of Relativistic Supernovae Lacking a Gamma-Ray Burst Detection

    Science.gov (United States)

    Milisavljevic, D.; Margutti, R.; Parrent, J. T.; Soderberg, A. M.; Fesen, R. A.; Mazzali, P.; Maeda, K.; Sanders, N. E.; Cenko, S. B.; Silverman, J. M.

    2014-01-01

    We present ultraviolet, optical, and near-infrared observations of SN2012ap, a broad-lined Type Ic supernova in the galaxy NGC 1729 that produced a relativistic and rapidly decelerating outflow without a gamma-ray burst signature. Photometry and spectroscopy follow the flux evolution from -13 to +272 days past the B-band maximum of -17.4 +/- 0.5 mag. The spectra are dominated by Fe II, O I, and Ca II absorption lines at ejecta velocities of v approx. 20,000 km s(exp. -1) that change slowly over time. Other spectral absorption lines are consistent with contributions from photospheric He I, and hydrogen may also be present at higher velocities (v approx. greater than 27,000 km s(exp. -1)). We use these observations to estimate explosion properties and derive a total ejecta mass of 2.7 Solar mass, a kinetic energy of 1.0×1052 erg, and a (56)Ni mass of 0.1-0.2 Solar mass. Nebular spectra (t > 200 d) exhibit an asymmetric double-peaked [O I] lambda lambda 6300, 6364 emission profile that we associate with absorption in the supernova interior, although toroidal ejecta geometry is an alternative explanation. SN2012ap joins SN2009bb as another exceptional supernova that shows evidence for a central engine (e.g., black-hole accretion or magnetar) capable of launching a non-negligible portion of ejecta to relativistic velocities without a coincident gamma-ray burst detection. Defining attributes of their progenitor systems may be related to notable properties including above-average environmental metallicities of Z approx. greater than Solar Z, moderate to high levels of host-galaxy extinction (E(B -V ) > 0.4 mag), detection of high-velocity helium at early epochs, and a high relative flux ratio of [Ca II]/[O I] > 1 at nebular epochs. These events support the notion that jet activity at various energy scales may be present in a wide range of supernovae.

  3. THE BROAD-LINED Type Ic SN 2012ap AND THE NATURE OF RELATIVISTIC SUPERNOVAE LACKING A GAMMA-RAY BURST DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Milisavljevic, D.; Margutti, R.; Parrent, J. T.; Soderberg, A. M.; Sanders, N. E.; Kamble, A.; Chakraborti, S.; Drout, M. R.; Kirshner, R. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Fesen, R. A. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF (United Kingdom); Maeda, K. [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Silverman, J. M. [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Filippenko, A. V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Pickering, T. E. [Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Kawabata, K. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Hattori, T. [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States); Hsiao, E. Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Stritzinger, M. D., E-mail: dmilisav@cfa.harvard.edu [Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C (Denmark); and others

    2015-01-20

    We present ultraviolet, optical, and near-infrared observations of SN 2012ap, a broad-lined Type Ic supernova in the galaxy NGC 1729 that produced a relativistic and rapidly decelerating outflow without a gamma-ray burst signature. Photometry and spectroscopy follow the flux evolution from –13 to +272 days past the B-band maximum of –17.4 ± 0.5 mag. The spectra are dominated by Fe II, O I, and Ca II absorption lines at ejecta velocities of v ≈ 20,000 km s{sup –1} that change slowly over time. Other spectral absorption lines are consistent with contributions from photospheric He I, and hydrogen may also be present at higher velocities (v ≳ 27,000 km s{sup –1}). We use these observations to estimate explosion properties and derive a total ejecta mass of ∼2.7 M {sub ☉}, a kinetic energy of ∼1.0 × 10{sup 52} erg, and a {sup 56}Ni mass of 0.1-0.2 M {sub ☉}. Nebular spectra (t > 200 days) exhibit an asymmetric double-peaked [O I] λλ6300, 6364 emission profile that we associate with absorption in the supernova interior, although toroidal ejecta geometry is an alternative explanation. SN 2012ap joins SN 2009bb as another exceptional supernova that shows evidence for a central engine (e.g., black hole accretion or magnetar) capable of launching a non-negligible portion of ejecta to relativistic velocities without a coincident gamma-ray burst detection. Defining attributes of their progenitor systems may be related to notable observed properties including environmental metallicities of Z ≳ Z {sub ☉}, moderate to high levels of host galaxy extinction (E(B – V) > 0.4 mag), detection of high-velocity helium at early epochs, and a high relative flux ratio of [Ca II]/[O I] >1 at nebular epochs. These events support the notion that jet activity at various energy scales may be present in a wide range of supernovae.

  4. Delayed Nickel Decay in Gamma Ray Bursts

    CERN Document Server

    McLaughlin, G C

    2002-01-01

    Recently observed emission lines in the X-ray afterglow of gamma ray bursts suggest that iron group elements are either produced in the gamma ray burst, or are present nearby. If this material is the product of a thermonuclear burn, then such material would be expected to be rich in Nickel-56. If the nickel remains partially ionized, this prevents the electron capture reaction normally associated with the decay of Nickel-56, dramatically increasing the decay timescale. Here we examine the consequences of rapid ejection of a fraction of a solar mass of iron group material from the center of a collapsar/hypernova. The exact rate of decay then depends on the details of the ionization and therefore the ejection process. Future observations of iron, nickel and cobalt lines can be used to diagnose the origin of these elements and to better understand the astrophysical site of gamma ray bursts. In this model, the X-ray lines of these iron-group elements could be detected in suspected hypernovae that did not produce ...

  5. Physics of gamma-ray bursts

    Science.gov (United States)

    Lamb, D. Q.

    1984-01-01

    Attention is given to the accumulating evidence for the view that gamma-ray bursts come from strongly magnetic neutron stars, discussing the physical properties of the emission region and the radiation processes expected in strong magnetic fields, and emphasizing that the observed burst spectra require that the emission region be optically thin. This entails that the energy of the emitting plasma and/or the plasma itself be continuously replenished during a burst, and that the cooling time scale of the emitting plasma be much shorter than the observed duration of the bursts. This characteristic of the cooling time scale implies that the burst intensity and spectrum can vary on extremely short time scales, and that the burst duration must have a separate explanation. It is emphasized that synchrotron emission is favored as the gamma-ray production mechanism; it is the only mechanism capable of satisfying the optical thinness constraint while producing the observed luminosity.

  6. Swift observations of gamma-ray bursts.

    Science.gov (United States)

    Gehrels, Neil

    2007-05-15

    Since its launch on 20 November 2004, the Swift mission has been detecting approximately 100 gamma-ray bursts (GRBs) each year, and immediately (within approx. 90s) starting simultaneous X-ray and UV/optical observations of the afterglow. It has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and a rapid follow-up by other observatories notified through the GCN. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations and the conclusion that short GRBs can occur in non-star-forming galaxies or regions, whereas long GRBs are strongly concentrated within the star-forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z approximately 5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to a much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and the association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova.

  7. Fermi/GBM Observations of SGR J0501+4516 Bursts

    CERN Document Server

    Lin, Lin; Baring, Matthew G; van der Horst, Alexander J; Guiriec, Sylvain; Woods, Peter M; Gogus, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Granot, Jonathan; Preece, Robert; von Kienlin, Andreas; Chaplin, Vandiver; Watts, Anna L; Wijers, Ralph A M J; Zhang, Shuang Nan; Bhat, Narayan; Finger, Mark H; Gehrels, Neil; Harding, Alice; Kaper, Lex; Kaspi, Victoria; Mcenery, Julie; Meegan, Charles A; Paciesas, William S; Pe'er, Asaf; Ramirez-Ruiz, Enrico; van der Klis, Michiel; Wachter, Stefanie; Wilson-Hodge, Colleen

    2011-01-01

    We present our temporal and spectral analyses of 29 bursts from SGR J0501+4516, detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope during the 13 days of the source activation in 2008 (August 22 to 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 T90s 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 black body functions. We expand on the physical interpretation of these two models and we compare their p...

  8. A Scientific Trigger Unit for Space-Based Real-Time Gamma Ray Burst Detection, II - Data Processing Model and Benchmarks

    CERN Document Server

    Provost, Hervé Le; Flouzat, Christophe; Kestener, Pierre; Chaminade, Thomas; Donati, Modeste; Château, Frédéric; Daly, François; Fontignie, Jean

    2014-01-01

    The Scientific Trigger Unit (UTS) is a satellite equipment designed to detect Gamma Ray Bursts (GRBs) observed by the onboard 6400 pixels camera ECLAIRs. It is foreseen to equip the low-Earth orbit French-Chinese satellite SVOM and acts as the GRB trigger unit for the mission. The UTS analyses in real-time and in great details the onboard camera data in order to select the GRBs, to trigger a spacecraft slew re-centering each GRB for the narrow field-of-view instruments, and to alert the ground telescope network for GRB follow-up observations. A few GRBs per week are expected to be observed by the camera; the UTS targets a close to 100% trigger efficiency, while being selective enough to avoid fake alerts. This is achieved by running the complex scientific algorithms on a radiation tolerant hardware, based on a FPGA data pre-processor and a CPU with a Real-Time Operating System. The UTS is a scientific software, firmware and hardware co-development. A Data Processing Model (DPM) has been developed to fully val...

  9. X-ray burst-induced spectral variability in 4U 1728-34

    Science.gov (United States)

    Kajava, J. J. E.; Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J.

    2017-03-01

    Aims: INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time it has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, also known as the slow burster. Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods: We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results: We constructed a hardness intensity diagram to track spectral state variations. In the soft state, the energy spectra are characterized by two thermal components likely coming from the accretion disc and the boundary/spreading layer, together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state, the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an additional component: either a powerlaw tail or reflection. By stacking 123 X-ray bursts in the hard state, we detect emission up to 80 keV during the X-ray bursts. We find that during the bursts the emission above 40 keV decreases by a factor of approximately three with respect to the persistent emission level. Conclusions: Our results suggest that the enhanced X-ray burst emission changes the spectral properties of the accretion disc in the hard state. The likely cause is an X-ray burst induced cooling of the electrons in the inner hot flow near the neutron star.

  10. 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

  11. Power Enhancement Cavity for Burst-Mode Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yun [ORNL

    2015-01-01

    We demonstrate a novel optical cavity scheme and locking method that can realize the power enhancement of picosecond UV laser pulses operating at a burst mode with arbitrary burst (macropulse) lengths and repetition rates.

  12. THE FIVE YEAR FERMI/GBM MAGNETAR BURST CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Collazzi, A. C. [SciTec, Inc., 100 Wall Street, Princeton, NJ 08540 (United States); Kouveliotou, C.; Horst, A. J. van der; Younes, G. A. [Department of Physics, The George Washington University, 725 21st Street NW, Washington, DC 20052 (United States); Kaneko, Y.; Göğüş, E. [Sabancı University, Orhanlı-Tuzla, İstanbul 34956 (Turkey); Lin, L. [François Arago Centre, APC, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris (France); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Raanana 43537 (Israel); Finger, M. H. [Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Chaplin, V. L. [School of Medicine, Vanderbilt University, 1161 21st Avenue S, Nashville, TN 37232 (United States); Huppenkothen, D. [Center for Data Science, New York University, 726 Broadway, 7th Floor, New York, NY 10003 (United States); Watts, A. L. [Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Kienlin, A. von [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H., E-mail: acollazzi@scitec.com [Jacobs Technology, Inc., Huntsville, AL (United States); and others

    2015-05-15

    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.

  13. Dynamic Behavior of Microbubbles during Long Ultrasound Tone-Burst Excitation: Mechanistic Insights into Ultrasound-Microbubble Mediated Therapeutics Using High-Speed Imaging and Cavitation Detection.

    Science.gov (United States)

    Chen, Xucai; Wang, Jianjun; Pacella, John J; Villanueva, Flordeliza S

    2016-02-01

    Ultrasound (US)-microbubble (MB)-mediated therapies have been found to restore perfusion and enhance drug/gene delivery. On the presumption that MBs do not persist during long US exposure under high acoustic pressures, most schemes use short US pulses when a high US pressure is employed. However, we recently observed an enhanced thrombolytic effect using long US pulses at high acoustic pressures. Therefore, we explored the fate of MBs during long tone-burst exposures (5 ms) at various acoustic pressures and MB concentrations via direct high-speed optical observation and passive cavitation detection. MBs first underwent stable or inertial cavitation depending on the acoustic pressure and then formed gas-filled clusters that continued to oscillate, break up and form new clusters. Cavitation detection confirmed continued, albeit diminishing, acoustic activity throughout the 5-ms US excitation. These data suggest that persisting cavitation activity during long tone bursts may confer additional therapeutic effects.

  14. 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...

  15. 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...

  16. 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.

  17. Prospects of detecting the QCD phase transition in the Galactic supernova neutrino burst with 20-kton scale liquid scintillation detectors

    Science.gov (United States)

    Petkov, V. B.

    2016-06-01

    The supernova explosion in the Galaxy is a rare event; that is why the comprehensive study of the next one has absolute priority for the low-energy neutrino astronomy. Because the detailed explosion mechanism has not been unambiguously identified yet and the surrounding matter envelope is opaque for photons, the neutrinos only can give information about physical conditions, dynamics of the collapse, and the SN mechanism. Furthermore, neutrinos could potentially reveal new physics (e.g. QCD phase transition) operating deep in the stellar core.

  18. Statistical properties of SGR 1806-20 bursts

    NARCIS (Netherlands)

    Göğüş, E.; Woods, P.M.; Kouveliotou, C.; van Paradijs, J.; Briggs, M.S.; Duncan, R.C.; Thompson, C.

    2000-01-01

    We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence d

  19. The accretion rate dependence of burst oscillation amplitude

    CERN Document Server

    Ootes, Laura S; Galloway, Duncan K; Wijnands, Rudy

    2016-01-01

    Neutron stars in low mass X-ray binaries exhibit oscillations during thermonuclear bursts, attributed to asymmetric brightness patterns on the burning surfaces. All models that have been proposed to explain the origin of these asymmetries (spreading hotspots, surface waves, and cooling wakes) depend on the accretion rate. By analysis of archival RXTE data of six oscillation sources, we investigate the accretion rate dependence of the amplitude of burst oscillations. This more than doubles the size of the sample analysed previously by Muno et al. (2004), who found indications for a relationship between accretion rate and oscillation amplitudes. We find that burst oscillation signals can be detected at all observed accretion rates. Moreover, oscillations at low accretion rates are found to have relatively small amplitudes ($A_\\text{rms}\\leq0.10$) while oscillations detected in bursts observed at high accretion rates cover a broad spread in amplitudes ($0.05\\leq A_\\text{rms}\\leq0.20$). In this paper we present t...

  20. Soft X-ray Extended Emissions of Short Gamma-Ray Bursts as Electromagnetic Counterparts of Compact Binary Mergers; Possible Origin and Detectability

    CERN Document Server

    Nakamura, Takashi; Nakauchi, Daisuke; Suwa, Yudai; Sakamoto, Takanori; Kawai, Nobuyuki

    2013-01-01

    We investigate the possible origin of extended emissions (EE) of short gamma-ray bursts (SGRBs) with an isotropic energy of $\\sim 10^{50\\mbox{-}51} \\ \\rm erg$ and a duration of $\\sim 100 \\ \\rm s$, based on the compact binary (neutron star (NS)-NS or NS-black hole (BH)) merger scenario. We analyze the evolution of magnetized neutrino-dominated accretion disks of mass $\\sim 0.1 \\ M_\\odot$ around BHs formed after the mergers, and estimate the power of relativistic outflows via the Blandford-Znajek (BZ) process. We show that a rotation energy of the BH up to $\\sim 10^{53} \\ \\rm erg$ can be extracted with a time scale of $\\sim 100 \\ \\rm s$ with a disk viscosity parameter of $\\alpha \\sim 0.01$. Such a BZ power dissipates by clashing with non-relativistic pre-ejected matter of mass $M \\sim 10^{-(2\\mbox{-}4)} \\ M_\\odot$, and form a mildly relativistic fireball. We show that the dissipative photospheric emissions from such fireballs are likely in soft X-ray band ($1\\mbox{-}10 \\ \\rm keV$) for $M \\sim 10^{-2} M_\\odot$ p...

  1. Burst Mechanisms in Hydrodynamics

    CERN Document Server

    Knobloch, E

    1999-01-01

    Different mechanisms believed to be responsible for the generation of bursts in hydrodynamical systems are reviewed and a new mechanism capable of generating regular or irregular bursts of large dynamic range near threshold is described. The new mechanism is present in the interaction between oscillatory modes of odd and even parity in systems of large but finite aspect ratio, and provides an explanation for the bursting behavior observed in binary fluid convection. Additional applications of the new mechanism are proposed.

  2. Gamma photometric redshifts for long gamma-ray bursts

    CERN Document Server

    Bagoly, Z; Mészáros, A; Mészáros, P; Horváth, I; Balázs, L G; Vavrek, R

    2003-01-01

    It is known that the soft tail of the gamma-ray bursts' spectra show excesses from the exact power-law dependence. In this article we show that this departure can be detected in the peak flux ratios of different BATSE DISCSC energy channels. This effect allows to estimate the redshift of the bright long gamma-ray bursts in the BATSE Catalog. A verification of these redshifts is obtained for the 8 GRB which have both BATSE DISCSC data and measured optical spectroscopic redshifts. There is good correlation between the measured and esti redshifts, and the average error is $\\Delta z \\approx 0.33$. The method is similar to the photometric redshift estimation of galaxies in the optical range, hence it can be called as "gamma photometric redshift estimation". The estimated redshifts for the long bright gamma-ray bursts are up to $z \\simeq 4$. For the the faint long bursts - which should be up to $z \\simeq 20$ - the redshifts cannot be determined unambiguously with this method.

  3. Propeller tone bursts

    Science.gov (United States)

    Succi, G. P.; Munro, D. H.; Ingard, K. U.

    1983-01-01

    Intense high frequency (25-38 kHz) tone bursts have been observed in acoustic tests of a scale model of a general aviation propeller. The amplitude of the tone burst is approximately equal to the amplitude of the propeller noise signature. The conditions necessary for the production of these tone bursts are described. The experiments indicate that the origin of these bursts is a periodic flow oscillation on the suction surface of the propeller blade tips which may be due to the interaction between an oscillating shock wave and a laminar boundary layer.

  4. 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.

  5. Observing a Burst with Sunglasses

    Science.gov (United States)

    2003-11-01

    polarisation properties of the afterglow of GRB 030329 as it developed after the explosion. Hypernovae, the source of GRBs, are indeed so far away that they can only be seen as unresolved points of light. To probe their spatial structure, astronomers have thus to rely on a trick: polarimetry (see ESO PR 23/03). Polarimetry works as follows: light is composed of electromagnetic waves which oscillate in certain directions (planes). Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflecting off a pond. The radiation in a gamma-ray burst is generated in an ordered magnetic field, as so-called synchrotron radiation [3]. If the hypernova is spherically symmetric, all orientations of the electromagnetic waves will be present equally and will average out, so there will be no net polarisation. If, however, the gas is not ejected symmetrically, but into a jet, a slight net polarisation will be imprinted on the light. This net polarisation will change with time since the opening angle of the jet widens with time, and we see a different fraction of the emission cone. Studying the polarisation properties of the afterglow of a gamma-ray burst thus allows to gain knowledge about the underlying spatial structures and the strength and orientation of the magnetic field in the region where the radiation is generated. " And doing this over a long period of time, as the afterglow fades and evolves, provides us with a unique diagnostic tool for gamma-ray burst studies ", says Jochen Greiner . Although previous single measurements of the polarisation of GRB's optical afterglow exist, no detailed study has ever been done of the evolution of polarisation with time. This is indeed a very demanding task, only possible with an extremely stable instrument on the largest telescope... and a sufficient bright optical afterglow. As soon as GRB 030329 was detected, the team of

  6. Broad-band modelling of short gamma-ray bursts with energy injection from magnetar spin-down and its implications for radio detectability

    NARCIS (Netherlands)

    B.P. Gompertz; A.J. van der Horst; P.T. O'Brien; G.A. Wynn; K. Wiersema

    2015-01-01

    The magnetar model has been proposed to explain the apparent energy injection in the X-ray light curves of short gamma-ray bursts (SGRBs), but its implications across the full broad-band spectrum are not well explored. We investigate the broad-band modelling of four SGRBs with evidence for energy in

  7. Research on Data Accurate Perceptual Social Information Network Evolution,Modeling and Burst Detection Based on Kernel Synergy%基于核协同数据精准感知的社会信息网络演化、建模及突发检测研究

    Institute of Scientific and Technical Information of China (English)

    刘畅

    2015-01-01

    目前,社会计算和面向网络化社会的研究在许多国家都被提升到了国家战略层次,成为了学术界的研究热点和前沿课题。社会信息网络(SIN)作为社会计算的重要研究内容也是我们应该关注的对象。内容包括数据精准感知型核协同SIN构建、多维协同感知型SIN演化分析、动态SIN建模和SIN上的突发检测进行了系统描述,不但可以为SIN研究提供理论支持,而且也可为涉及社会和谐发展的SIN上的突发检测应用提供新方法。%At present,the research on social computing and network oriented society, which has been elevated to the national strategic level in many countries,has become the focus and advanced subject of academic.Social information network (SIN) should be paid more attention to,as the object of important research contents of social computing. SIN,including the data accurate perception of nuclear burst detection,collaborative SIN build multidimensional cooperative sensing type SIN evolution analysis, the burst detection of dynamic SIN modeling and SIN of the system description, can not only provide theoretical support for SIN research, but also provide a new method for relates to the harmonious development of society on the SIN burst detection application.

  8. GRB 050505: A high redshift burst discovered by Swift

    CERN Document Server

    Hurkett, C P; Page, K L; Rol, E; Goad, M R; O'Brien, P T; Beardmore, A; Godet, O; Burrows, D N; Tanvir, N R; Levan, A; Zhang, B; Malesani, D; Hill, J E; Kennea, J A; Chapman, R; La Parola, V; Perri, M; Romano, P; Gehrels, R S N

    2006-01-01

    We report the discovery and subsequent multi-wavelength afterglow behaviour of the high redshift (z = 4.27) Gamma Ray Burst GRB 050505. This burst is the third most distant burst, measured by spectroscopic redshift, discovered after GRB 000131 (z = 4.50) and GRB 050904 (z = 6.29). GRB 050505 is a long GRB with a multipeaked gamma-ray light curve, with a duration of T_90 = 63+/-2 s and an inferred isotropic release in gamma-rays of ~4.44 x 10^53 ergs in the 1-10^4 keV rest frame energy range. The Swift X-Ray Telescope followed the afterglow for 14 days, detecting two breaks in the light curve at 7.4(+/-1.5) ks and 58.0 (+9.9/-15.4) ks after the burst trigger. The power law decay slopes before, between and after these breaks were 0.25 (+0.16/-0.17), 1.17 (+0.08/-0.09) and 1.97 (+0.27/-0.28) respectively. The light curve can also be fit with a `smoothly broken' power law model with a break observed at ~ T+18.5 ks, with decay slopes of ~0.4 and ~1.8 before and after the break respectively. The X-ray afterglow sho...

  9. 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...

  10. Plasma Bursts in Deep Penetration Laser Welding

    Science.gov (United States)

    Mrňa, L.; Šarbort, M.

    We present an experimental study of the deep penetration laser welding process which aims to analyze the plasma plume oscillations on a short time scale. Using the high-speed camera we show that the plasma comes out of the keyhole in the form of short bursts rather than the continuous flow. We detect these bursts as the short-time intensity oscillations of light emissions coming from the plasma plume. We determine the period of bursts using the statistical signal processing methods and the short-time frequency analysis. Finally, we compare the characteristics of plasma bursts and the geometry of resulting welds carried out on a 2 kW Yb:YAG laser welding machine for the steel workpiece and various welding parameters settings.

  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. Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion

    CERN Document Server

    Zand, J J M in 't

    2010-01-01

    A small subset of thermonuclear X-ray bursts on neutron stars exhibit such a strong photospheric expansion that for a few seconds the photosphere is located at a radius r_ph greater than ~1000 km. Such `superexpansions' imply a large and rapid energy release, a feature characteristic of pure He burst models. Calculations have shown that during a pure He burst, the freshly synthesized heavy-element ashes of burning can be ejected in a strong radiative wind and produce significant spectral absorption features. We find 32 superexpansion bursts from 8 different systems with the following interesting features: (1) At least 7 out of 8 systems are (candidate) ultracompact X-ray binaries in which the neutron star accretes hydrogen-deficient fuel, suggesting that these bursts indeed ignite in a helium-rich layer. (2) In two bursts we detect strong absorption edges during the expansion phase. The edge energies and depths are consistent with the H-like edge of iron-peak elements with abundances greater than ~100 times s...

  13. Gamma ray bursts and their afterglows

    Science.gov (United States)

    Nicuesa Guelbenzu, A.

    2017-03-01

    Gamma-Ray Bursts (GRBs) were among the greatest mysteries in modern astrophysics. They were first observed 50 years ago but it took three decades before optical counterparts could be found and the underlying physical phenomena studied in detail. GRB research represents currently one of the most rapidly growing areas in extragalactic astronomy. This is due in large part to the numerous connections that GRBs have with other disciplines like cosmology, supernovae, stellar evolution, nuclear physics, astroparticle and gravitational wave astronomy. Therefore, their study is of great importance to understand various astrophysical phenomena such as the formation of the first stars, the chemical evolution and the expansion of the Universe. Since gamma radiation can travel along cosmological distances without being affected by any possible intervening absorption, GRBs can be detected from the most distant universe, reaching redshifts up to z = 10 or more.

  14. Nitrogen-detected CAN and CON experiments as alternative experiments for main chain NMR resonance assignments.

    Science.gov (United States)

    Takeuchi, Koh; Heffron, Gregory; Sun, Zhen-Yu J; Frueh, Dominique P; Wagner, Gerhard

    2010-08-01

    Heteronuclear direct-detection experiments, which utilize the slower relaxation properties of low gamma nuclei, such as (13)C have recently been proposed for sequence-specific assignment and structural analyses of large, unstructured, and/or paramagnetic proteins. Here we present two novel (15)N direct-detection experiments. The CAN experiment sequentially connects amide (15)N resonances using (13)C(alpha) chemical shift matching, and the CON experiment connects the preceding (13)C' nuclei. When starting from the same carbon polarization, the intensities of nitrogen signals detected in the CAN or CON experiments would be expected four times lower than those of carbon resonances observed in the corresponding (13)C-detecting experiment, NCA-DIPAP or NCO-IPAP (Bermel et al. 2006b; Takeuchi et al. 2008). However, the disadvantage due to the lower gamma is counteracted by the slower (15)N transverse relaxation during detection, the possibility for more efficient decoupling in both dimensions, and relaxation optimized properties of the pulse sequences. As a result, the median S/N in the (15)N observe CAN experiment is 16% higher than in the (13)C observe NCA-DIPAP experiment. In addition, significantly higher sensitivity was observed for those residues that are hard to detect in the NCA-DIPAP experiment, such as Gly, Ser and residues with high-field C(alpha) resonances. Both CAN and CON experiments are able to detect Pro resonances that would not be observed in conventional proton-detected experiments. In addition, those experiments are free from problems of incomplete deuterium-to-proton back exchange in amide positions of perdeuterated proteins expressed in D(2)O. Thus, these features and the superior resolution of (15)N-detected experiments provide an attractive alternative for main chain assignments. The experiments are demonstrated with the small model protein GB1 at conditions simulating a 150 kDa protein, and the 52 kDa glutathione S-transferase dimer, GST.

  15. Gamma-Ray Burst Class Properties

    Science.gov (United States)

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

    2000-01-01

    Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the Burst and Transient Source Experiment (BATSE) instrument, we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 (high fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E (sub peak) alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram.

  16. Statistical Properties of SGR 1806-20 Bursts.

    Science.gov (United States)

    Göğüş; Woods; Kouveliotou; van Paradijs J; Briggs; Duncan; Thompson

    2000-04-01

    We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.

  17. The Integral Burst Alert System (IBAS)

    CERN Document Server

    Mereghetti, S; Borkowski, J J; Walter, R; Pedersen, H

    2003-01-01

    We describe the INTEGRAL Burst Alert System (IBAS): the automatic software for the rapid distribution of the coordinates of the Gamma-Ray Bursts detected by INTEGRAL. IBAS is implemented as a ground based system, working on the near-real time telemetry stream. During the first six months of operations, six GRB have been detected in the field of view of the INTEGRAL instruments and localized by IBAS. Positions with an accuracy of a few arcminutes are currently distributed by IBAS to the community for follow-up observations within a few tens of seconds of the event.

  18. Distribution of whistler mode bursts at Venus

    Science.gov (United States)

    Scarf, F. L.; Jordan, K. F.; Russell, C. T.

    1987-01-01

    Several thousand impulsive whistler mode noise bursts were detected by the Pioneer Venus wave instrument during the first 10 seasons with nightside traversals at low altitudes. The altitude distribution for these events shows that essentially all of the bursts were detected when the orbiter was less than 2000 km above the planet, suggesting that the varying plasma conditions could not maintain coherent whistler mode field-aligned guidance over greater distances. Within the 2000-km range, the distribution of the number of events versus altitude shows that there are two distinct subregions. These results are interpreted in terms of two types of whistler mode propagation from sources below the ionosphere.

  19. 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

  20. Correction of the recording artifacts and detection of the functional deviations in ECG by means of syndrome decoding with an automatic burst error correction of the cyclic codes using periodograms for determination of code component spectral range

    Directory of Open Access Journals (Sweden)

    Evgenie D. Adamoviс

    2016-05-01

    Full Text Available Aims This paper describes a novel approach to the analysis of electrocardiographic data based on the consideration of the repetitive P, Q, R, S, T sequences as cyclic codes. In Part I we introduce a principle similar to the syndrome decoding using the control numbers, which allows correcting the noise combinations. Materials and methods We propose to apply the burst-error-correcting algorithms for automatic detection of the ECG artifacts and the functional abnormalities, including those compared to the reference model. Our approach is compared to the symbolic dynamics methods in cardiology practice. During the automated search of the code components (i.e. point values and spectral ranges one-to-one corresponding to P, Q, R, S, T considered in Part II, the authors apply the Lomb-Scargle periodogram method with the phase control which allows to determine the code components not only from the main harmonics, but also using the sidebands, avoiding the phase errors. Results The results of the method testing on rats with the heart failure using a simplified telemetric recording from the implantable chips are given in Part III. A complete independence of the results of the determination of the code points (fingerprints from the variables for which the calculation is performed is shown. We also prove the robustness of the above approach with respect to the most types of the non-adaptive filtration. Conclusion The above method can be useful not only for experimental medicine, but also for veterinary and clinical diagnostic practice. This method is adequately reproducable both on animals and human ECG, except for some constant values.

  1. A new burst assembly technique for supporting QoS in optical burst switching networks

    Institute of Scientific and Technical Information of China (English)

    Xiaolong Yang(阳小龙); Mingrui Dang(党明瑞); Youju Mao(毛幼菊); Lemin Li(李乐民)

    2003-01-01

    This letter proposes a new burst assembly technique for supporting QoS in optical burst switching (OBS)networks. It consists of the adaptive-threshold burst assembly mechanism and QoS-based random offset-time scheme. The assembly mechanism, which is fit well to multi-class burst assembly, not only matcheswith IP QoS mechanism based on packet classification, and also utilizes fairly and efficiently assemblycapacity. Based on token-bucket model and burst segment selective discard (BSSD), the offset-time schemecan smooth the traffic to support OBS QoS. The simulation results show that the technique can improvethe performance in terms of packet loss probability (PLP).

  2. Localization of Gamma-Ray Bursts using the Fermi Gamma-Ray Burst Monitor

    CERN Document Server

    Connaughton, V; Goldstein, A; Meegan, C A; Paciesas, W S; Preece, R D; Wilson-Hodge, C A; Gibby, M H; Greiner, J; Gruber, D; Jenke, P; Kippen, R M; Pelassa, V; Xiong, S; Yu, H -F; Bhat, P N; Burgess, J M; Byrne, D; Fitzpatrick, G; Foley, S; Giles, M M; Guiriec, S; van der Horst, A J; von Kienlin, A; McBreen, S; McGlynn, S; Tierney, D; Zhang, B -B

    2014-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 Gamma-Ray Bursts (GRBs) since it began science operations in July, 2008. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network (IPN), to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1 degree, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.7 degree Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14 degrees. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y-axis better l...

  3. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    Energy Technology Data Exchange (ETDEWEB)

    Connaughton, V.; Briggs, M. S.; Burgess, J. M. [CSPAR and Physics Department, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Goldstein, A.; Wilson-Hodge, C. A. [Astrophysics Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Meegan, C. A.; Jenke, P.; Pelassa, V.; Xiong, S.; Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Paciesas, W. S. [Universities Space Research Association, Huntsville, AL (United States); Preece, R. D. [Department of Space Science, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H. [Jacobs Technology, Inc., Huntsville, AL (United States); Greiner, J.; Yu, H.-F. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Kippen, R. M. [Los Alamos National Laboratory, NM 87545 (United States); Byrne, D.; Fitzpatrick, G.; Foley, S., E-mail: valerie@nasa.gov [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); and others

    2015-02-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1°, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.°7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14°. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.

  4. A simple optimization can improve the performance of single feature polymorphism detection by Affymetrix expression arrays

    Directory of Open Access Journals (Sweden)

    Fujisawa Hironori

    2010-05-01

    Full Text Available Abstract Background High-density oligonucleotide arrays are effective tools for genotyping numerous loci simultaneously. In small genome species (genome size: Results We compared the single feature polymorphism (SFP detection performance of whole-genome and transcript hybridizations using the Affymetrix GeneChip® Rice Genome Array, using the rice cultivars with full genome sequence, japonica cultivar Nipponbare and indica cultivar 93-11. Both genomes were surveyed for all probe target sequences. Only completely matched 25-mer single copy probes of the Nipponbare genome were extracted, and SFPs between them and 93-11 sequences were predicted. We investigated optimum conditions for SFP detection in both whole genome and transcript hybridization using differences between perfect match and mismatch probe intensities of non-polymorphic targets, assuming that these differences are representative of those between mismatch and perfect targets. Several statistical methods of SFP detection by whole-genome hybridization were compared under the optimized conditions. Causes of false positives and negatives in SFP detection in both types of hybridization were investigated. Conclusions The optimizations allowed a more than 20% increase in true SFP detection in whole-genome hybridization and a large improvement of SFP detection performance in transcript hybridization. Significance analysis of the microarray for log-transformed raw intensities of PM probes gave the best performance in whole genome hybridization, and 22,936 true SFPs were detected with 23.58% false positives by whole genome hybridization. For transcript hybridization, stable SFP detection was achieved for highly expressed genes, and about 3,500 SFPs were detected at a high sensitivity (> 50% in both shoot and young panicle transcripts. High SFP detection performances of both genome and transcript hybridizations indicated that microarrays of a complex genome (e.g., of Oryza sativa can be

  5. X-ray Spectroscopy of Bursts from SGR 1806-20 with RXTE

    CERN Document Server

    Strohmayer, T E; Strohmayer, Tod E.; Ibrahim, Alaa

    1998-01-01

    We report on new RXTE X-ray spectral analysis of bursts from SGR 1806-20, the most prolific SGR source known. Previous studies of bursts from this source revealed a remarkable lack of spectral variability both in single bursts as well as from burst to burst. We present here some of the first evidence for significant spectral evolution within SGR bursts. We find that optically thin thermal bremsstrahlung (OTTB) spectra including photoelectric absorption provide the best fits to most bursts, however, other models (power law, Band GRB) can also produce statistically acceptable fits. We confirm the existence of a rolloff in the photon number spectrum below 5 keV.

  6. GLAST Burst Monitor Trigger Classification Algorithm

    Science.gov (United States)

    Perrin, D. J.; Sidman, E. D.; Meegan, C. A.; Briggs, M. S.; Connaughton, V.

    2004-01-01

    The Gamma Ray Large Area Space Telescope (GLAST), currently set for launch in the first quarter of 2007, will consist of two instruments, the GLAST Burst Monitor (GBM) and the Large Area Telescope (LAT). One of the goals of the GBM is to identify and locate gamma-ray bursts using on-board software. The GLAST observatory can then be re-oriented to allow observations by the LAT. A Bayesian analysis will be used to distinguish gamma-ray bursts from other triggering events, such as solar flares, magnetospheric particle precipitation, soft gamma repeaters (SGRs), and Cygnus X-1 flaring. The trigger parameters used in the analysis are the burst celestial coordinates, angle from the Earth's horizon, spectral hardness, and the spacecraft geomagnetic latitude. The algorithm will be described and the results of testing will be presented.

  7. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra

    2016-01-01

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

  8. PCR detection of thermophilic spore-forming bacteria involved in canned food spoilage.

    Science.gov (United States)

    Prevost, S; Andre, S; Remize, F

    2010-12-01

    Thermophilic bacteria that form highly heat-resistant spores constitute an important group of spoilage bacteria of low-acid canned food. A PCR assay was developed in order to rapidly trace these bacteria. Three PCR primer pairs were designed from rRNA gene sequences. These primers were evaluated for the specificity and the sensitivity of detection. Two primer pairs allowed detection at the species level of Geobacillus stearothermophilus and Moorella thermoacetica/thermoautrophica. The other pair allowed group-specific detection of anaerobic thermophilic bacteria of the genera Thermoanaerobacterium, Thermoanaerobacter, Caldanerobium and Caldanaerobacter. After a single enrichment step, these PCR assays allowed the detection of 28 thermophiles from 34 cans of spoiled low-acid food. In addition, 13 ingredients were screened for the presence of these bacteria. This PCR assay serves as a detection method for strains able to spoil low-acid canned food treated at 55°C. It will lead to better reactivity in the canning industry. Raw materials and ingredients might be qualified not only for quantitative spore contamination, but also for qualitative contamination by highly heat-resistant spores.

  9. Inferring the distances of fast radio bursts through associated 21-cm absorption

    Science.gov (United States)

    Margalit, Ben; Loeb, Abraham

    2016-07-01

    The distances of fast radio burst (FRB) sources are currently unknown. We show that the 21-cm absorption line of hydrogen can be used to infer the redshifts of FRB sources, and determine whether they are Galactic or extragalactic. We calculate a probability of ˜10 per cent for the host galaxy of an FRB to exhibit a 21-cm absorption feature of equivalent width ≳10 km s-1. Arecibo, along with several future radio observatories, should be capable of detecting such associated 21-cm absorption signals for strong bursts of ≳several Jy peak flux densities.

  10. Can Handheld Thermal Imaging Technology Improve Detection of Poachers in African Bushveldt?

    Directory of Open Access Journals (Sweden)

    Adam G Hart

    Full Text Available Illegal hunting (poaching is a global threat to wildlife. Anti-poaching initiatives are making increasing use of technology, such as infrared thermography (IRT, to support traditional foot and vehicle patrols. To date, the effectiveness of IRT for poacher location has not been tested under field conditions, where thermal signatures are often complex. Here, we test the hypothesis that IRT will increase the distance over which a poacher hiding in African scrub bushveldt can be detected relative to a conventional flashlight. We also test whether any increase in effectiveness is related to the cost and complexity of the equipment by comparing comparatively expensive (22,000 USD and relatively inexpensive (2000 USD IRT devices. To test these hypotheses we employ a controlled, fully randomised, double-blind procedure to find a poacher in nocturnal field conditions in African bushveldt. Each of our 27 volunteer observers walked three times along a pathway using one detection technology on each pass in randomised order. They searched a prescribed search area of bushveldt within which the target was hiding. Hiding locations were pre-determined, randomised, and changed with each pass. Distances of first detection and positive detection were noted. All technologies could be used to detect the target. Average first detection distance for flashlight was 37.3 m, improving by 19.8 m to 57.1 m using LIRT and by a further 11.2m to 68.3m using HIRT. Although detection distances were significantly greater for both IRTs compared to flashlight, there was no significant difference between LIRT and HIRT. False detection rates were low and there was no significant association between technology and accuracy of detection. Although IRT technology should ideally be tested in the specific environment intended before significant investment is made, we conclude that IRT technology is promising for anti-poaching patrols and that for this purpose low cost IRT units are as

  11. Gamma-ray bursts observed by the watch experiment

    DEFF Research Database (Denmark)

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

    1991-01-01

    After two years in orbit the WATCH instruments on the GRANAT space observatory have localized seven gamma burst sources with better than 1° accuracy. In several cases, follow‐up observations with Schmidt telescopes have been made within a few days. Some of the bursts have also been detected...

  12. 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)

  13. A polarised fast radio burst at low Galactic latitude

    Science.gov (United States)

    Petroff, Emily; SUPERB Collaboration; HESS Collaboration; ANTARES Collaboration

    2017-01-01

    Fast radio bursts (FRBs) are a growing population of transients detected with radio telescopes which are thought to originate outside the Milky Way. Fewer than 20 sources exist in the literature and the majority of bursts have been found away from the plane of the Galaxy or where the Galactic contribution to the total electron column density is low. Here we report on the discovery of a new burst, FRB 150215, discovered with the Parkes radio telescope in real-time in February 2015. The burst was found to be 43±5% linearly polarised with an imprecisely determined rotation measure (RM) consistent with zero. The burst was followed-up with 9 telescopes to search for radio, optical, X-ray, γ-ray and neutrino emission from the location of the burst. No transient or variable emission was found to be associated with the burst and no repeat pulses have been observed in nine hours of Parkes observations. Radio images of the field were obtained following the FRB but would not have been sensitive enough to pick up a signal like the one emanating from WISE J071634.59-190039.2 following FRB150418 if it had been present. The sightline to the burst is close to the Galactic plane and the Galactic RM foreground may approach a null along this sightline, corresponding to a decreased total electron column density from the Milky Way. This might explain why this burst was detectable at low latitude whereas previous searches have been relatively unsuccessful.

  14. A search for optical counterparts of gamma-ray bursts. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hye-Sook

    1995-03-09

    Gamma Ray Bursts (GRBS) are mysterious flashes of gamma rays lasting several tens to hundreds of seconds that occur approximately once per day. NASA launched the orbiting Compton Gamma Ray Observatory to study GRBs and other gamma ray phenomena. CGRO carries the Burst and Transient Experiment (BATSE) specifically to study GRBS. Although BATSE has collected data on over 600 GRBS, and confirmed that GRBs are localized, high intensity point sources of MeV gamma rays distributed isotropically in the sky, the nature and origin of GRBs remains a fundamental problem in astrophysics. BATSE`s 8 gamma ray sensors located on the comers of the box shaped CGRO can detect the onset of GRBs and record their intensity and energy spectra as a function of time. The position of the burst on the sky can be determined to < {plus_minus}10{degrees} from the BATSE data stream. This position resolution is not sufficient to point a large, optical telescope at the exact position of a GRB which would determine its origin by associating it with a star. Because of their brief duration it is not known if GRBs are accompanied by visible radiation. Their seemingly large energy output suggests thatthis should be. Simply scaling the ratio of visible to gamma ray intensities of the Crab Nebula to the GRB output suggests that GRBs ought to be accompanied by visible flashes of magnitude 10 or so. A few photographs of areas containing a burst location that were coincidentally taken during the burst yield lower limits on visible output of magnitude 4. The detection of visible light during the GRB would provide information on burst physics, provide improved pointing coordinates for precise examination of the field by large telescope and provide the justification for larger dedicated optical counterpart instruments. The purpose of this experiment is to detect or set lower limits on optical counterpart radiation simultaneously accompanying the gamma rays from

  15. Can a central blood volume deficit be detected by systolic pressure variation during spontaneous breathing?

    DEFF Research Database (Denmark)

    Dahl, Michael; Hayes, Chris Frederick; Steen Rasmussen, Bodil;

    2016-01-01

    BACKGROUND: Whether during spontaneous breathing arterial pressure variations (APV) can detect a volume deficit is not established. We hypothesized that amplification of intra-thoracic pressure oscillations by breathing through resistors would enhance APV to allow identification of a reduced card...

  16. Can GPS Be Used to Detect Deleterious Progression in Training Volume Among Runners?

    NARCIS (Netherlands)

    Nielsen, Rasmus O.; Cederholm, Peter; Buist, Ida; Sorensen, Henrik; Lind, Martin; Rasmussen, Sten

    2013-01-01

    Nielsen, RO, Cederholm, P, Buist, I, SOrensen, H, Lind, M, and Rasmussen, S. Can GPS be used to detect deleterious progression in training volume among runners? J Strength Cond Res 27(6): 1471-1478, 2013There is a need to ascertain if an association exists between excessive progression in weekly vol

  17. Burst error correction extensions for large Reed Solomon codes

    Science.gov (United States)

    Owsley, P.

    1990-01-01

    Reed Solomon codes are powerful error correcting codes that include some of the best random and burst correcting codes currently known. It is well known that an (n,k) Reed Solomon code can correct up to (n - k)/2 errors. Many applications utilizing Reed Solomon codes require corrections of errors consisting primarily of bursts. In this paper, it is shown that the burst correcting ability of Reed Solomon codes can be increased beyond (n - k)/2 with an acceptable probability of miscorrect.

  18. Broadband modelling of short gamma-ray bursts with energy injection from magnetar spin-down and its implications for radio detectability

    CERN Document Server

    Gompertz, B P; O'Brien, P T; Wynn, G A; Wiersema, K

    2014-01-01

    The magnetar model has been proposed to explain the apparent energy injection in the X-ray light curves of short gamma-ray bursts (SGRBs), but its implications across the full broadband spectrum are not well explored. We investigate the broadband modelling of four SGRBs with evidence for energy injection in their X-ray light curves, applying a physically motivated model in which a newly-formed magnetar injects energy into a forward shock as it loses angular momentum along open field lines. By performing an order of magnitude search for the underlying physical parameters in the blast wave, we constrain the characteristic break frequencies of the synchrotron spectrum against their manifestations in the available multi-wavelength observations for each burst. The application of the magnetar energy injection profile restricts the succesful matches to a limited family of models that are self-consistent within the magnetic dipole spin-down framework. Because of this, we are able to produce synthetic light curves tha...

  19. 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...

  20. Inferring the Distances of Fast Radio Bursts Through 21-cm Absorption

    CERN Document Server

    Margalit, Ben

    2015-01-01

    The distances of Fast Radio Burst (FRB) sources are currently unknown. We show that the 21-cm absorption line of hydrogen can be used to infer the redshifts of FRB sources, and determine whether they are Galactic or extragalactic. We calculate a probability of $\\sim 10\\%$ for detecting a 21-cm equivalent width $\\gtrsim 4 ~\\mathrm{km}~\\mathrm{s}^{-1}$. The forthcoming SKA observatory provides ideal prospects for detecting our predicted signal.

  1. 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

  2. Characterizing Oscillatory Bursts in Single-Trial EEG Data

    Science.gov (United States)

    Knuth, K. H.; Shah, A. S.; Lakatos, P.; Schroeder, C. E.

    2004-01-01

    Oscillatory bursts in numerous bands ranging from low (theta) to high frequencies (e.g., gamma) undoubtedly play an important role in cortical dynamics. Largely because of the inadequacy of existing analytic techniques. however, oscillatory bursts and their role in cortical processing remains poorly understood. To study oscillatory bursts effectively one must be able to isolate them and characterize them in the single trial. We describe a series of straightforward analysis techniques that produce useful indices of burst characteristics. First, stimulus-evoked responses are estimated using Differentially Variable Component Analysis (dVCA), and are subtracted from the single-trial. The single-trial characteristics of the evoked responses are stored to identify possible correlations with burst activity. Time-frequency (T-F), or wavelet, analyses are then applied to the single trial residuals. While T-F plots have been used in recent studies to identify and isolate bursts, we go further by fitting each burst in the T-F plot with a two-dimensional Gaussian. This provides a set of burst characteristics, such as, center time. burst duration, center frequency. frequency dispersion. and amplitude, all of which contribute to the accurate characterization of the individual burst. The burst phase can also be estimated. Burst characteristics can be quantified with several standard techniques (e.g.. histogramming and clustering), as well as Bayesian techniques (e.g., blocking) to allow a more parametric description analysis of the characteristics of oscillatory bursts, and the relationships of specific parameters to cortical excitability and stimulus integration.

  3. Constraints on an Optical Afterglow and on Supernova Light Following the Short Burst GRB 050813

    Science.gov (United States)

    Ferrero, P.; Sanchez, S. F.; Kann, D. A.; Klose, S.; Greiner, J.; Gorosabel, J.; Hartmann, D. H.; Henden, A. A.; Moller, P.; Palazzi, E.; Rau, A.; Stecklum, B.; Castro-Tirado, A. J.; Fynbok J. P. U.; Hjorth, J.; Jakobsson, P.; Kouveliotou, C.; Masetti, N.; Pian, E.; Tanvir, N. R.; Wijers, R. A. M. J.

    2006-01-01

    We report early follow-up observations of the error box of the short burst 050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada (OSN), followed by deep VLT/FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. No evidence for a GRB afterglow was found in our Calar Alto and OSN data, no rising supernova component was detected in our FORS2 images. A potential host galaxy can be identified in our FORS2 images, even though we cannot state with certainty its association with GRB 050813. IN any case, the optical afterglow of GRB 050813 was very faint, well in agreement with what is known so far about the optical properties of afterglows of short bursts. We conclude that all optical data are not in conflict with the interpretation that GRB 050813 was a short burst.

  4. When can ocean acidification impacts be detected from decadal alkalinity measurements?

    Science.gov (United States)

    Carter, B. R.; Frölicher, T. L.; Dunne, J. P.; Rodgers, K. B.; Slater, R. D.; Sarmiento, J. L.

    2016-04-01

    We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty.

  5. The Glast Burst Monitor

    Science.gov (United States)

    Meegan, Charles

    2000-01-01

    The Gamma-Ray Large Area Space Telescope (GLAST) will include a secondary instrument to augment the observatory's capabilities for GRB studies. The GLAST Burst Monitor (GBK is a collaboration between Marshall Space Flight Center, the University of Huntsville, Alabama, and the Max Plank Institute for Extraterrestrial Physics. The purpose of the GBM is to extend energy coverage below the main instrument's lower limit of about 20 MeV, and to provide an on-board burst trigger and approximate location. The instrument consists of twelve NaI detectors and two BGO detectors. This combination provides energy coverage from a few keV up to about 30 MeV.

  6. Review of GRANAT observations of gamma-ray bursts

    DEFF Research Database (Denmark)

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

    1995-01-01

    The GRANAT observatory was launched into a high apogee orbit on 1 December, 1989. Three instruments onboard GRANAT - PHEBUS, WATCH and SIGMA are able to detect gamma-ray bursts in a very broad energy range from 6 keV up to 100 MeV. Over 250 gamma-ray bursts were detected. We discuss the results...... of four differently behaving componenents in gamma-ray burst spectra is discussed. Statistical properties of the gamma-ray burst sources based on the 5 years of observations with (∼ 10−6 erg/cm2) sensitivity as well as the results of high sensitivity (∼ 10−8 erg/cm2) search for Gamma-Ray Bursts within...... the SIGMA telescope field of view are reviewed....

  7. Detecting shifts in diversity limits from molecular phylogenies: what can we know?

    Science.gov (United States)

    McInnes, Lynsey; Orme, C David L; Purvis, A

    2011-11-01

    Large complete species-level molecular phylogenies can provide the most direct information about the macroevolutionary history of clades having poor fossil records. However, extinction will ultimately erode evidence of pulses of rapid speciation in the deep past. Assessment of how well, and for how long, phylogenies retain the signature of such pulses has hitherto been based on a--probably untenable--model of ongoing diversity-independent diversification. Here, we develop two new tests for changes in diversification 'rules' and evaluate their power to detect sudden increases in equilibrium diversity in clades simulated with diversity-dependent speciation and extinction rates. Pulses of diversification are only detected easily if they occurred recently and if the rate of species turnover at equilibrium is low; rates reported for fossil mammals suggest that the power to detect a doubling of species diversity falls to 50 per cent after less than 50 Myr even with a perfect phylogeny of extant species. Extinction does eventually draw a veil over past dynamics, suggesting that some questions are beyond the limits of inference, but sudden clade-wide pulses of speciation can be detected after many millions of years, even when overall diversity is constrained. Applying our methods to existing phylogenies of mammals and angiosperms identifies intervals of elevated diversification in each.

  8. An Accurate and Efficient Algorithm for Detection of Radio Bursts with an Unknown Dispersion Measure, for Single-dish Telescopes and Interferometers

    Science.gov (United States)

    Zackay, Barak; Ofek, Eran O.

    2017-01-01

    Astronomical radio signals are subjected to phase dispersion while traveling through the interstellar medium. To optimally detect a short-duration signal within a frequency band, we have to precisely compensate for the unknown pulse dispersion, which is a computationally demanding task. We present the “fast dispersion measure transform” algorithm for optimal detection of such signals. Our algorithm has a low theoretical complexity of 2{N}f{N}t+{N}t{N}{{Δ }}{{log}}2({N}f), where Nf, Nt, and NΔ are the numbers of frequency bins, time bins, and dispersion measure bins, respectively. Unlike previously suggested fast algorithms, our algorithm conserves the sensitivity of brute-force dedispersion. Our tests indicate that this algorithm, running on a standard desktop computer and implemented in a high-level programming language, is already faster than the state-of-the-art dedispersion codes running on graphical processing units (GPUs). We also present a variant of the algorithm that can be efficiently implemented on GPUs. The latter algorithm’s computation and data-transport requirements are similar to those of a two-dimensional fast Fourier transform, indicating that incoherent dedispersion can now be considered a nonissue while planning future surveys. We further present a fast algorithm for sensitive detection of pulses shorter than the dispersive smearing limits of incoherent dedispersion. In typical cases, this algorithm is orders of magnitude faster than enumerating dispersion measures and coherently dedispersing by convolution. We analyze the computational complexity of pulsed signal searches by radio interferometers. We conclude that, using our suggested algorithms, maximally sensitive blind searches for dispersed pulses are feasible using existing facilities. We provide an implementation of these algorithms in Python and MATLAB.

  9. 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.

  10. GRB Catalog: Bursts from Vela to Swift

    Science.gov (United States)

    Angelini, L.

    2008-01-01

    Gamma ray burst (GRB) astronomy started when the first event was recorded on July 2, 1967 by Vela 4a and 4b. Since then many missions have flown experiments capable of detecting GRBs. The events collected by these older experiments are mostly available in paper copy, each containing a few ten to a few hundred bursts. No systematic effort in cataloging of these bursts has been available. In some cases the information is unpublished and in others difficult to retrieve. The first major GRB catalog was obtained by GRO with the BATSE experiment. It contains more than 2000 bursts and includes homogeneous information for each of the bursts. With the launch of Swift, the first Gamma-ray/X-ray mission dedicated to the study of GRBs and their afterglows, a wealth of information is collected by the Swift instrument as well as from ground-based telescopes. This talk will describe the efforts to create a comprehensive GRBCAT and its current status and future prospective.

  11. Gamma-Ray Burst at the extreme: "the naked-eye burst" GRB 080319B

    CERN Document Server

    Wozniak, P R; Panaitescu, A D; Wren, J A; Davis, H R; White, R R

    2008-01-01

    On 19 March 2008, the northern sky was the stage of a spectacular optical transient that for a few seconds remained visible to the naked eye. The transient was associated with GRB 080319B, a gamma-ray burst at a luminosity distance of about 6 Gpc (standard cosmology), making it the most luminous optical object ever recorded by human kind. We present comprehensive sky monitoring and multi-color optical follow-up observations of GRB 080319B collected by the RAPTOR telescope network covering the development of the explosion and the afterglow before, during, and after the burst. The extremely bright prompt optical emission revealed features that are normally not detectable. The optical and gamma-ray variability during the explosion are correlated, but the optical flux is much greater than can be reconciled with single emission mechanism and a flat gamma-ray spectrum. This extreme optical behavior is best understood as synchrotron self-Compton model (SSC). After a gradual onset of the gamma-ray emission, there is ...

  12. Can one detect small-scale turbulence from standard meteorological radiosondes?

    Directory of Open Access Journals (Sweden)

    R. Wilson

    2011-02-01

    Full Text Available It has been recently proposed by Clayson and Kantha (2008 to evaluate the climatology of atmospheric turbulence in the free atmosphere by applying a Thorpe analysis on standard radiosoundings obtained with relatively low resolution (LR in the vertical. Since then, several studies based on this idea have been published. However, the impact of instrumental noise on the detection of turbulent layers was completely ignored in these works. The present study aims to evaluate the feasibility of turbulence detection from radiosoundings. For this purpose, we analyzed data of two field campaigns during which high-resolution (HR soundings (10–20 cm were performed simultaneously with standard LR soundings. We here used the raw data of standard radiosondes, the vertical resolution ranging from 5 to 8 m.

    A Thorpe analysis was performed on both LR and HR potential temperature profiles. A denoising procedure was first applied in order to reduce the probability of occurrence of artificial inversions, i.e. inversions due to instrumental noise only. We then compare the empirical probability of the sizes of the selected overturns from LR and HR profiles.

    From HR profiles in the troposphere, the scales of the detected turbulent overturns range from 4 to ~1000 m. The shape of the distribution of the size of overturns is found to sharply decrease with increasing scales. From LR profiles, the smallest scale of detected overturns is ~32 m, a similar decrease in the shape of the size distribution being observed. These results suggest that turbulent events can indeed be detected from standard radiosondes measurements in the troposphere. However these events are rather rare as they belong to the tail of the size distribution of the turbulent overturns: they only represent the 7% largest events. Similar conclusions are obtained from radiosondes data collected in the lower stratosphere, but the fraction of the detectable events is even smaller than in the

  13. Can one detect small-scale turbulence from standard meteorological radiosondes?

    Directory of Open Access Journals (Sweden)

    R. Wilson

    2011-05-01

    Full Text Available It has been recently proposed by Clayson and Kantha (2008 to evaluate the climatology of atmospheric turbulence through the detection of overturns in the free atmosphere by applying a Thorpe analysis on relatively low vertical resolution (LR profiles collected from standard radiosoundings. Since then, several studies based on this idea have been published. However, the impact of instrumental noise on the detection of turbulent layers was completely ignored in these works. The present study aims to evaluate the feasibility of overturns detection from radiosoundings. For this purpose, we analyzed data of two field campaigns during which high-resolution (HR soundings (10–20 cm were performed simultaneously with standard LR soundings. We used the raw data of standard meteorological radiosondes, the vertical resolution ranging from 5 to 9 m.

    A Thorpe analysis was applied to both LR and HR potential temperature profiles. A denoising procedure was first applied in order to reduce the probability of occurrence of artificial overturns, i.e. potential temperature inversions due to instrumental noise only. We then compared the empirical probability density functions (pdf of the sizes of the selected overturns from LR and HR profiles.

    From HR profiles measured in the troposphere, the sizes of the detected overturns range from 4 to ~1000 m. The shape of the size pdf of overturns is found to sharply decrease with increasing scales. From LR profiles, the smallest size of detected overturns is ~32 m, a similar decrease in the shape of the pdf of sizes being observed. These results suggest that overturns, resulting either from small-scale turbulence or from instabilities, can indeed be detected from meteorological radiosonde measurements in the troposphere and in the stratosphere as well. However they are rather rare as they belong to the tail of the size distribution of overturns: they only represent the 7 % largest events in the troposphere

  14. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

    central engine activity and compare the model results with the observational data. We show that the observed X-ray flare phenomenology can be explained within the internal shock model. The number, width and occurring time of flares are then used to diagnose the central engine activity, putting constraints on the energy, ejection time, width and number of ejected shells. We find that the observed X-ray flare time history generally reflects the time history of the central engine, which reactivates multiple times after the prompt emission phase with progressively reduced energy. This shell model code can be used to constrain broadband observations of GRB 090926A, which showed two flares in both the Swift UVOT and XRT bands. Using the prompt emission fluence to constrain the total energy contained in the blastwave, the internal shock model requires that Lorentz factors of the shells causing flares must be less than the Lorentz factor of the blastwave when the shells are ejected. Recent observations of Gamma-Ray Bursts (GRBs) by the Fermi Large Area Telescope (LAT) revealed a power law decay feature of the high energy emission (above 100 MeV), which led to the suggestion that it originates from an external shock. We analyze four GRBs (080916C, 090510, 090902B and 090926A) jointly detected by Fermi LAT and Gamma-ray Burst Monitor (GBM), which have high quality lightcurves in both instrument energy bands. Using the MeV prompt emission (GBM) data, we can record the energy output from the central engine as a function of time. Assuming a constant radiative efficiency, we are able to track energy accumulation in the external shock using our internal/external shell model code and show that the late time lightcurves fit well within the external shock model, but the early time lightcurves are dominated by the internal shock component which has a shallow decay phase due to the initial pile-up of shells onto the blast wave.

  15. Pair Production Absorption Troughs in $\\gamma$-Ray Burst Spectra A Potential Distance Discriminator

    CERN Document Server

    Baring, M G; Baring, Matthew G.; Harding, Alice K.

    1997-01-01

    Relativistic bulk motion with large Lorentz factors has recently been inferred for gamma-ray bursts regardless of whether they are of galactic or cosmological origin. This conclusion results from calculations of internal pair production transparency in bursts that usually assume an infinite power-law source spectrum for simplicity, an approximation that is quite adequate for some bursts detected by EGRET. However, for a given bulk Lorentz factor sub-MeV photons in such calculations. Hence it is essential to accurately address the spectral curvature in bursts seen by BATSE. In this paper we present the major properties induced in photon-photon opacity considerations by such spectral curvature. The observed spectral breaks around 1 MeV turn out to be irrelevant to opacity in cosmological bursts, but are crucial to estimates of source transparency in the 1 GeV -- 1 TeV range for sources located in the galactic halo. We find that broad absorption troughs can arise at these energies for suitable bulk motion parame...

  16. Application of burst vibrothermography to characterize planar vertical cracks

    Science.gov (United States)

    Mendioroz, Arantza; Celorrio, Ricardo; Cifuentes, Ángel; Zatón, Lander; Salazar, Agustín.

    2016-05-01

    We present a method to characterize vertical cracks in a fast way using burst vibrothermography. In this technique the sample is excited by ultrasounds and, at the defect, rubbing of the contacting surfaces produces heat that can be detected as a temperature rise at the surface using an infrared camera. In this work, first we present the solution of the direct problem, i.e., the calculation of the surface temperature distribution produced by a vertical heat source representing a crack excited by an ultrasound burst, and we choose the information that will be used to characterize the crack, namely, one thermogram and one timing-graph. Next we address the inverse problem, consisting of finding the heat source distribution that is responsible for the observed surface temperature. This inverse problem is ill-posed, and a naïve inversion process is unstable. We propose to use three penalty terms, based on zero order Tikhonov and Total Variation functionals and the Lasso method, to stabilize the inversion. By inverting synthetic data, we analyze the performance of the algorithm as a function of the depth of the heat source and we study the effect of the burst duration and noise level in the data on the quality of the reconstructions. Finally, we invert experimental data taken in samples containing calibrated heat sources. The results show that it is possible to characterize vertical cracks down to depths of 6 mm in AISI 304 stainless steel.

  17. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    Science.gov (United States)

    Mingarelli, Chiara; Levin, Janna; Lazio, Joseph

    2016-03-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic (EM) luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs), NS-BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak. The main burst is from the peak luminosity before merger, while the post-merger burst follows from the NS magnetic field migration to the BH, causing a shock. NS-BH pairs are desirable for ground-based gravitational wave (GW) observatories since the pair might not be detected any other way, with EM counterparts augmenting the scientific leverage beyond the GW signal. Valuably, EM signal can break degeneracies in the parameters encoded in the GW as well as probe the NS magnetic field strength, yielding insights into open problems in NS magnetic field decay.

  18. The Fluence and Distance Distributions of Fast Radio Bursts

    Science.gov (United States)

    Vedantham, H. K.; Ravi, V.; Hallinan, G.; Shannon, R. M.

    2016-10-01

    Fast radio bursts (FRB) are millisecond-duration radio pulses with apparent extragalactic origins. All but two of the FRBs have been discovered using the Parkes dish, which employs multiple beams formed by an array of feed horns on its focal plane. In this paper, we show that (i) the preponderance of multiple-beam detections and (ii) the detection rates for varying dish diameters can be used to infer the index α of the cumulative fluence distribution function (the logN–logF function: α = 1.5 for a non-evolving population in a Euclidean universe). If all detected FRBs arise from a single progenitor population, multiple-beam FRB detection rates from the Parkes telescope yield the constraint 0.52 the universe.

  19. How Accurately Can Your Wrist Device Recognize Daily Activities and Detect Falls?

    Directory of Open Access Journals (Sweden)

    Martin Gjoreski

    2016-06-01

    Full Text Available Although wearable accelerometers can successfully recognize activities and detect falls, their adoption in real life is low because users do not want to wear additional devices. A possible solution is an accelerometer inside a wrist device/smartwatch. However, wrist placement might perform poorly in terms of accuracy due to frequent random movements of the hand. In this paper we perform a thorough, large-scale evaluation of methods for activity recognition and fall detection on four datasets. On the first two we showed that the left wrist performs better compared to the dominant right one, and also better compared to the elbow and the chest, but worse compared to the ankle, knee and belt. On the third (Opportunity dataset, our method outperformed the related work, indicating that our feature-preprocessing creates better input data. And finally, on a real-life unlabeled dataset the recognized activities captured the subject’s daily rhythm and activities. Our fall-detection method detected all of the fast falls and minimized the false positives, achieving 85% accuracy on the first dataset. Because the other datasets did not contain fall events, only false positives were evaluated, resulting in 9 for the second, 1 for the third and 15 for the real-life dataset (57 days data.

  20. How Accurately Can Your Wrist Device Recognize Daily Activities and Detect Falls?

    Science.gov (United States)

    Gjoreski, Martin; Gjoreski, Hristijan; Luštrek, Mitja; Gams, Matjaž

    2016-06-01

    Although wearable accelerometers can successfully recognize activities and detect falls, their adoption in real life is low because users do not want to wear additional devices. A possible solution is an accelerometer inside a wrist device/smartwatch. However, wrist placement might perform poorly in terms of accuracy due to frequent random movements of the hand. In this paper we perform a thorough, large-scale evaluation of methods for activity recognition and fall detection on four datasets. On the first two we showed that the left wrist performs better compared to the dominant right one, and also better compared to the elbow and the chest, but worse compared to the ankle, knee and belt. On the third (Opportunity) dataset, our method outperformed the related work, indicating that our feature-preprocessing creates better input data. And finally, on a real-life unlabeled dataset the recognized activities captured the subject's daily rhythm and activities. Our fall-detection method detected all of the fast falls and minimized the false positives, achieving 85% accuracy on the first dataset. Because the other datasets did not contain fall events, only false positives were evaluated, resulting in 9 for the second, 1 for the third and 15 for the real-life dataset (57 days data).

  1. Gravitational wave burst search in the Virgo C7 data

    Energy Technology Data Exchange (ETDEWEB)

    Acernese, F; Barone, F [INFN, sezione di Napoli, Universita di Salerno, Fisciano, I-84084 Salerno (Italy); Alshourbagy, M; Barsotti, L; Bigotta, S; Bonelli, L [INFN, Sezione di Pisa, Universita di Pisa, I-56127 Pisa (Italy); Antonucci, F; Astone, P [INFN, Sezione di Roma, I-00185 Roma (Italy); Aoudia, S; Birindelli, S; Bondu, F [Departement Artemis, Observatoire de la Cote d' Azur, CNRS, F-06304 Nice (France); Arun, K G; Bizouard, M-A [LAL, Universite Paris-Sud, IN2P3/CNRS, F-91898 Orsay (France); Ballardin, G [European Gravitational Observatory (EGO), I-56021 Cascina (Pi) (Italy); Barsuglia, M [AstroParticule et Cosmologie (APC), CNRS: UMR7164-IN2P3-Observatoire de Paris-Universite Denis Diderot-Paris VII-CEA : DSM/IRFU (France); Bauer, Th. S [National institute for subatomic physics, NL-1009 DB (Netherlands); Boccara, C [ESPCI, CNRS, F-75005 Paris (France); Braccini, S; Bradaschia, C [INFN, Sezione di Pisa, I-56127 Pisa (Italy); Bosi, L

    2009-04-21

    A search for gravitational wave burst events has been performed with the Virgo C7 commissioning run data that have been acquired in September 2005 over 5 days. It focused on unmodeled short duration signals in the frequency range 150 Hz to 2 kHz. A search aimed at detecting the GW emission from the merger and ring-down phases of binary black hole coalescences was also carried out. An extensive understanding of the data was required to be able to handle a burst search using the output of only one detector. A 90% confidence level upper limit on the number of expected events given the Virgo C7 sensitivity curve has been derived as a function of the signal strength, for unmodeled gravitational wave searches. The sensitivity of the analysis presented is, in terms of the root sum square strain amplitude, h{sub rss} approx = 10{sup -20} Hz{sup -1/2}. This can be interpreted in terms of a frequentist upper limit on the rate R{sub 90%} of detectable gravitational wave bursts at the level of 1.1 events per day at a 90% confidence level. From the binary black hole search, we obtained the distance reach at 50% and 90% efficiency as a function of the total mass of the final black hole. The maximal detection distance for non-spinning high and equal mass black hole binary system obtained by this analysis in C7 data is approx =2.9 +- 0.1 Mpc for a detection efficiency of 50% for a binary of total mass 80 M{sub o-dot}.

  2. Studying the WHIM with Gamma Ray Bursts

    CERN Document Server

    Branchini, E; Corsi, A; Martizzi, D; Amati, L; Herder, J W den; Galeazzi, M; Gendre, B; Kaastra, J; Moscardini, L; Nicastro, F; Ohashi, T; Paerels, F; Piro, L; Roncarelli, M; Takei, Y; Viel, M

    2009-01-01

    We assess the possibility to detect and characterize the physical state of the missing baryons at low redshift by analyzing the X-ray absorption spectra of the Gamma Ray Burst [GRB] afterglows, measured by a micro calorimeters-based detector with 3 eV resolution and 1000 cm2 effective area and capable of fast re-pointing, similar to that on board of the recently proposed X-ray satellites EDGE and XENIA. For this purpose we have analyzed mock absorption spectra extracted from different hydrodynamical simulations used to model the properties of the Warm Hot Intergalactic Medium [WHIM]. These models predict the correct abundance of OVI absorption lines observed in UV and satisfy current X-ray constraints. According to these models space missions like EDGE and XENIA should be able to detect about 60 WHIM absorbers per year through the OVII line. About 45 % of these have at least two more detectable lines in addition to OVII that can be used to determine the density and the temperature of the gas. Systematic error...

  3. Analog Computer-Aided Detection (CAD) information can be more effective than binary marks.

    Science.gov (United States)

    Cunningham, Corbin A; Drew, Trafton; Wolfe, Jeremy M

    2017-02-01

    In socially important visual search tasks, such as baggage screening and diagnostic radiology, experts miss more targets than is desirable. Computer-aided detection (CAD) programs have been developed specifically to improve performance in these professional search tasks. For example, in breast cancer screening, many CAD systems are capable of detecting approximately 90% of breast cancer, with approximately 0.5 false-positive detections per image. Nevertheless, benefits of CAD in clinical settings tend to be small (Birdwell, 2009) or even absent (Meziane et al., 2011; Philpotts, 2009). The marks made by a CAD system can be "binary," giving the same signal to any location where the signal is above some threshold. Alternatively, a CAD system presents an analog signal that reflects strength of the signal at a location. In the experiments reported, we compare analog and binary CAD presentations using nonexpert observers and artificial stimuli defined by two noisy signals: a visible color signal and an "invisible" signal that informed our simulated CAD system. We found that analog CAD generally yielded better overall performance than binary CAD. The analog benefit is similar at high and low target prevalence. Our data suggest that the form of the CAD signal can directly influence performance. Analog CAD may allow the computer to be more helpful to the searcher.

  4. Dual view x-ray inspection system for foreign objects detection in canned food

    Science.gov (United States)

    Lu, Zhiwen; Peng, Ningsong

    2013-04-01

    X-ray inspection technique for foreign objects in food products can determine and mark the presence of contaminants within the product by using image processing and pattern recognition technique on the X-ray transmission images. This paper presents the dual view X-ray inspection technique for foreign objects in food jar via analyzing the weak points of the traditional single view X-ray inspection technique. In addition, a prototype with the new technique is developed in accordance with glass splinters detection within the food jar (glass jar especially) which is a typical tickler. Some algorithms such as: adaptive image segmentation based on contour tracking, nonlinear arctan function transform and etc., are applied to improve image quality and achieve effective inspection results. The false recognition rate is effectively reduced and the detection sensitivity is highly enhanced. Finally the actual test results of this prototype are given.

  5. 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...

  6. Bursting synchronization in clustered neuronal networks

    Institute of Scientific and Technical Information of China (English)

    Yu Hai-Tao; Wang Jiang; Deng Bin; Wei Xi-Le

    2013-01-01

    Neuronal networks in the brain exhibit the modular (clustered) property,i.e.,they are composed of certain subnetworks with differential internal and external connectivity.We investigate bursting synchronization in a clustered neuronal network.A transition to mutual-phase synchronization takes place on the bursting time scale of coupled neurons,while on the spiking time scale,they behave asynchronously.This synchronization transition can be induced by the variations of inter-and intracoupling strengths,as well as the probability of random links between different subnetworks.Considering that some pathological conditions are related with the synchronization of bursting neurons in the brain,we analyze the control of bursting synchronization by using a time-periodic external signal in the clustered neuronal network.Simulation results show a frequency locking tongue in the driving parameter plane,where bursting synchronization is maintained,even in the presence of external driving.Hence,effective synchronization suppression can be realized with the driving parameters outside the frequency locking region.

  7. Bursting and spiking due to additional direct and stochastic currents in neuron models

    Institute of Scientific and Technical Information of China (English)

    Yang Zhuo-Qin; Lu Qi-Shao

    2006-01-01

    Neurons at rest can exhibit diverse firing activities patterns in response to various external deterministic and random stimuli, especially additional currents. In this paper, neuronal firing patterns from bursting to spiking, induced by additional direct and stochastic currents, are explored in rest states Corresponding to two values of the parameter VK in the Chay neuron system. Three cases are considered by numerical simulation and fast/slow dynamic analysis, in which only the direct current or the stochastic current exists, or the direct and stochastic currents coexist. Meanwhile, several important bursting patterns in neuronal experiments, such as the period-1 "circle/homoclinic" bursting and the integer multiple "fold/homoclinic" bursting with one spike per burst, as well as the transition from integer multiple bursting to period-1 "circle/homoclinic" bursting and that from stochastic "Hopf/homoclinic" bursting to "Hopf/homoclinic" bursting, are investigated in detail.

  8. Can the dietary element content of virgin argan oils really be used for adulteration detection?

    Science.gov (United States)

    Mohammed, Faez A E; Bchitou, Rahma; Bouhaouss, Ahmed; Gharby, Saïd; Harhar, Hicham; Guillaume, Dominique; Charrouf, Zoubida

    2013-01-01

    Levels of eight dietary elements were assessed by ICP-AES in virgin edible and beauty argan oil samples prepared from four remote locations of the argan forest, and over a three-year period. The data showed sufficiently little variability to assess that all argan oil samples present, in terms of dietary elements, a similar composition, independently from the tree location within the argan forest. Therefore, adulteration detection by trace element analysis in edible and beauty argan oil is a method that can be generalised.

  9. Can upwelling signals be detected in intertidal fishes of different trophic levels?

    Science.gov (United States)

    Pulgar, J; Poblete, E; Alvarez, M; Morales, J P; Aranda, B; Aldana, M; Pulgar, V M

    2013-11-01

    For intertidal fishes belonging to three species, the herbivore Scartichthys viridis (Blenniidae), the omnivore Girella laevifrons (Kyphosidae) and the carnivore Graus nigra (Kyphosidae), mass and body size relationships were higher in individuals from an upwelling zone compared with those from a non-upwelling zone. RNA:DNA were higher in the herbivores and omnivores from the upwelling zone. Higher biomass and RNA:DNA in the upwelling intertidal fishes may be a consequence of an increased exposure to higher nutrient availability, suggesting that increased physiological conditioning in vertebrates from upwelling areas can be detected and measured using intertidal fishes of different trophic levels.

  10. 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...

  11. Infrared Imaging and Characterization of Exoplanets: Can we Detect Earth-Twins on a Budget?

    Science.gov (United States)

    Danchi, William

    2010-01-01

    During the past decade considerable progress has been made developing techniques that can be used to detect and characterize Earth twins in the mid- infrared (7-20 microns). The principal technique is called nulling interferometry, and it was invented by Bracewell in the late 1970's. The nulling technique is an interferometric equivalent of an optical coronagraph. At the present time most of the technological hurdles have been overcome for a space mission to be able to begin Phase A early in the next decade, and it is possible to detect and characterize Earth-twins on a mid- sized strategic mission budget ($600-800 million). I will review progress on this exciting method of planet detection in the context of recent work on the Exoplanet Community Forum and the US Decadal Survey (Astro2010), including biomarkers, technological progress, mission concepts, the theory of these instruments, and a.comparison of the discovery space of this technique with others also under consideration.

  12. You can hide but you have to run: direct detection with vector mediators

    CERN Document Server

    D'Eramo, Francesco; Panci, Paolo

    2016-01-01

    We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running and find that in some cases these bounds differ by several orders of magnitude. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Finally, we provide tools to facilitate th...

  13. Short-term synaptic plasticity can enhance weak signal detectability in nonrenewal spike trains.

    Science.gov (United States)

    Lüdtke, Niklas; Nelson, Mark E

    2006-12-01

    We study the encoding of weak signals in spike trains with interspike interval (ISI) correlations and the signals' subsequent detection in sensory neurons. Motivated by the observation of negative ISI correlations in auditory and electrosensory afferents, we assess the theoretical performance limits of an individual detector neuron receiving a weak signal distributed across multiple afferent inputs. We assess the functional role of ISI correlations in the detection process using statistical detection theory and derive two sequential likelihood ratio detector models: one for afferents with renewal statistics; the other for afferents with negatively correlated ISIs. We suggest a mechanism that might enable sensory neurons to implicitly compute conditional probabilities of presynaptic spikes by means of short-term synaptic plasticity. We demonstrate how this mechanism can enhance a postsynaptic neuron's sensitivity to weak signals by exploiting the correlation structure of the input spike trains. Our model not only captures fundamental aspects of early electrosensory signal processing in weakly electric fish, but may also bear relevance to the mammalian auditory system and other sensory modalities.

  14. The Broad-Lined Type Ic SN 2012ap and the Nature of Relativistic Supernovae Lacking a Gamma-ray Burst Detection

    CERN Document Server

    Milisavljevic, D; Parrent, J T; Soderberg, A M; Fesen, R A; Mazzali, P; Maeda, K; Sanders, N E; Cenko, S B; Silverman, J M; Filippenko, A V; Kamble, A; Chakraborti, S; Drout, M R; Kirshner, R P; Pickering, T E; Kawabata, K; Hattori, T; Hsiao, E Y; Stritzinger, M D; Marion, G H; Vinko, J; Wheeler, J C

    2014-01-01

    We present ultraviolet, optical, and near-infrared observations of SN 2012ap, a broad-lined Type Ic supernova in the galaxy NGC 1729 that produced a relativistic and rapidly decelerating outflow without a gamma-ray burst signature. Photometry and spectroscopy follow the flux evolution from -13 to +272 days past the B-band maximum of -17.4 +/- 0.5 mag. The spectra are dominated by Fe II, O I, and Ca II absorption lines at ejecta velocities of 20,000 km/s that change slowly over time. Other spectral absorption lines are consistent with contributions from photospheric He I, and hydrogen may also be present at higher velocities (> 27,000 km/s). We use these observations to estimate explosion properties and derive a total ejecta mass of 2.7 Msolar, a kinetic energy of 1.0x10^{52} erg, and a 56Ni mass of 0.1-0.2 Msolar. Nebular spectra (t > 200d) exhibit an asymmetric double-peaked [OI] 6300,6364 emission profile that we associate with absorption in the supernova interior, although toroidal ejecta geometry is an al...

  15. Ablation of steel using picosecond laser pulses in burst mode

    Science.gov (United States)

    Lickschat, Peter; Demba, Alexander; Weissmantel, Steffen

    2017-02-01

    Results obtained in picosecond laser processing of steel applying the burst mode are presented. Using the burst mode, pulse trains, i.e., bursts, consisting of a number of picosecond pulses with an inter-pulse delay of 12.5 ns and 10 ps pulse duration are applied for material processing. Small cavities with sizes in the range of the laser beam diameter made by single-burst ablation are compared to quadratic cavities of 0.5 × 0.5 mm² produced by multiburst ablation and simultaneous scanning of the laser beam across the steel sample surface. The ablated volume per pulse within the burst was calculated either from the ablated volume per burst or from the ablation depth of the quadratic cavities. With the second to fourth pulses in the bursts, a reduction of the ablated volume per pulse in comparison with the first pulse in the bursts (i.e., to the use of single pulses) was found for both single- and multiburst ablation, which is assumed to be due to plasma shielding. By contrast, the ablated volume per pulse within the bursts increases for the fifth to eighth pulses. Heat accumulation effect and the influence of the heated plasma can be assumed to be the reason for these higher ablation rates. SEM micrographs also show that there is a higher melt ejection out of the laser processed area. This is indicated by the formation of bulges about the ablated area.

  16. Can Remote Sensing Detect Aquifer Characteristics?: A Case Study in the Guarani Aquifer System

    Science.gov (United States)

    Richey, A. S.; Thomas, B.; Famiglietti, J. S.

    2013-12-01

    Global water supply resiliency depends on groundwater, especially regions threatened by population growth and climate change. Aquifer characteristics, even as basic as confined versus unconfined, are necessary to prescribe regulations to sustainably manage groundwater supplies. A significant barrier to sustainable groundwater management exists in the difficulties associated with mapping groundwater resources and characteristics at a large spatial scale. This study addresses this challenge by investigating if remote sensing, including with NASA's Gravity Recovery and Climate Experiment (GRACE), can detect and quantify key aquifer parameters and characteristics. We explore this through a case study in the Guarani Aquifer System (GAS) of South America, validating our remote sensing-based findings against the best available regional estimates. The use of remote sensing to advance the understanding of large aquifers is beneficial to sustainable groundwater management, especially in a trans-boundary system, where consistent information exchange can occur within hydrologic boundaries instead of political boundaries.

  17. RADIO FLARES FROM GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-20

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

  18. Meteor burst in the post 2000 era

    Science.gov (United States)

    Marriott, C.; Oduol, V.; Ghosh, A.; Tailor, B.

    In recent years a renewed interest has been shown in the possibility of using meteor burst links in tactical communications, both for networking and covert operations. Some of the applications that recent performance improvements would permit are evaluated. In evaluating the feasibility of a meteor burst implementation, certain technical and physical limitations are addressed. For the success of these applications, interoperability with other communication systems is necessary. The level of interoperability with other media, and the standards necessary to assure this interoperability are examined. Methods of minimizing and combating jamming are proposed. Meteor burst systems can be used in a large number of applications within a tactical environment. The principal disadvantage of the meteor burst medium is the problem of interference to other spectrum users from the probe end, and the interference from other users at the receiver end. The low throughput characteristic of meteor burst compares with some of the channel capacities used in other systems. Interoperability with other networks or communications links is relatively easy if certain straightforward protocols and standards are established.

  19. Magnetars and Gamma Ray Bursts

    CERN Document Server

    Bucciantini, N

    2012-01-01

    In the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I will review here the key aspects of the {\\it millisecond magnetar} model for Long Duration Gamma Ray Bursts (LGRBs). I will briefly describe what constraints, present observations put on any engine model, both in term of energetic, outflow properties, and the relation with the associated Supernova (SN). For each of these I will show how the millisecond magnetar model satisfies the requirements, what are the limits of the model, how can it be further tested, and what observations might be used to discriminate against it. I will also discuss numerical results that show the importance of the confinement by the progenitor star in explaining the formation of a collimated outflow, how a detailed model for the evolution of the central engine can be built, and show that a wide varie...

  20. Accessing the population of high redshift Gamma Ray Bursts

    CERN Document Server

    Ghirlanda, G; Ghisellini, G; Mereghetti, S; Tagliaferri, G; Campana, S; Osborne, J P; O'Brien, P; Tanvir, N; Willingale, R; Amati, L; Basa, S; Bernardini, M G; Burlon, D; Covino, S; D'Avanzo, P; Frontera, F; Gotz, D; Melandri, A; Nava, L; Piro, L; Vergani, S D

    2015-01-01

    Gamma Ray Bursts (GRBs) are a powerful probe of the high redshift Universe. We present a tool to estimate the detection rate of high-z GRBs by a generic detector with defined energy band and sensitivity. We base this on a population model that reproduces the observed properties of GRBs detected by Swift, Fermi and CGRO in the hard X-ray and gamma-ray bands. We provide the expected cumulative distributions of the flux and fluence of simulated GRBs in different energy bands. We show that scintillator detectors, operating at relatively high energies (e.g. tens of keV to the MeV), can detect only the most luminous GRBs at high redshifts due to the link between the peak spectral energy and the luminosity (Ep-Liso) of GRBs. We show that the best strategy for catching the largest number of high-z bursts is to go softer (e.g. in the soft X-ray band) but with a very high sensitivity. For instance, an imaging soft X-ray detector operating in the 0.2-5 keV energy band reaching a sensitivity, corresponding to a fluence o...

  1. Connecting protein and mRNA burst distributions for stochastic models of gene expression

    CERN Document Server

    Elgart, Vlad; Fenley, Andrew T; Kulkarni, Rahul V

    2011-01-01

    The intrinsic stochasticity of gene expression can lead to large variability in protein levels for genetically identical cells. Such variability in protein levels can arise from infrequent synthesis of mRNAs which in turn give rise to bursts of protein expression. Protein expression occurring in bursts has indeed been observed experimentally and recent studies have also found evidence for transcriptional bursting, i.e. production of mRNAs in bursts. Given that there are distinct experimental techniques for quantifying the noise at different stages of gene expression, it is of interest to derive analytical results connecting experimental observations at different levels. In this work, we consider stochastic models of gene expression for which mRNA and protein production occurs in independent bursts. For such models, we derive analytical expressions connecting protein and mRNA burst distributions which show how the functional form of the mRNA burst distribution can be inferred from the protein burst distributio...

  2. 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...

  3. A Burst Chasing X-ray Polarimeter

    Science.gov (United States)

    Hill, Joanne

    2007-01-01

    This viewgraph presentation reviews the rationale, design, and importance of an X-Ray Polarimeter. There is a brief discussion of Gamma Ray Bursts, followed by a review of the theories of Gamma-Ray Bursts Polarization. This leads to the question of "How do we measure the polarization?" and a discussion of the GRB x-ray emission, the photoelectric effect and photoelectric polarimetry. The requirements for the work, can only be approached using a gas detector. This leads to a discussion of a Micropattern Gas Polarimeter, and the Time-Projection Chamber (TPC) X-ray Polarimeter.

  4. Developing a system that can automatically detect health changes using transfer times of older adults

    Directory of Open Access Journals (Sweden)

    Greet Baldewijns

    2016-02-01

    Full Text Available Abstract Background As gait speed and transfer times are considered to be an important measure of functional ability in older adults, several systems are currently being researched to measure this parameter in the home environment of older adults. The data resulting from these systems, however, still needs to be reviewed by healthcare workers which is a time-consuming process. Methods This paper presents a system that employs statistical process control techniques (SPC to automatically detect both positive and negative trends in transfer times. Several SPC techniques, Tabular cumulative sum (CUSUM chart, Standardized CUSUM and Exponentially Weighted Moving Average (EWMA chart were evaluated. The best performing method was further optimized for the desired application. After this, it was validated on both simulated data and real-life data. Results The best performing method was the Exponentially Weighted Moving Average control chart with the use of rational subgroups and a reinitialization after three alarm days. The results from the simulated data showed that positive and negative trends are detected within 14 days after the start of the trend when a trend is 28 days long. When the transition period is shorter, the number of days before an alert is triggered also diminishes. If for instance an abrupt change is present in the transfer time an alert is triggered within two days after this change. On average, only one false alarm is triggered every five weeks. The results from the real-life dataset confirm those of the simulated dataset. Conclusions The system presented in this paper is able to detect both positive and negative trends in the transfer times of older adults, therefore automatically triggering an alarm when changes in transfer times occur. These changes can be gradual as well as abrupt.

  5. A novel implementation of TCP Vegas for optical burst switched networks

    KAUST Repository

    Shihada, Basem

    2010-07-01

    TCP performance over bufferless Optical Burst Switched (OBS) networks could be significantly degraded due to the misinterpretation of network congestion status (referred to as false congestion detection). It has been reported that burst retransmission in the OBS domain can improve the TCP throughput by hiding burst loss events from the upper TCP layer, which can effectively reduce the congestion window fluctuation at the expense of introducing additional delay. However, the additional delay may cause performance degradation for delay-based TCP implementations that are sensitive to packet round trip time in estimating the network congestion status. In this paper, a novel implementation of TCP Vegas that adopts a threshold-based mechanism is proposed for identifying the network congestion status in OBS networks. Analytical models are developed to evaluate the throughput of conventional TCP Vegas and threshold-based Vegas over OBS networks with burst retransmission. Simulation is conducted to validate the analytical model and to compare threshold-based Vegas with a number of legacy TCP implementations, such as TCP Sack and TCP Reno. The analytical model can be used to obtain a proper threshold value that results in an optimal steady state TCP throughput.

  6. Can GPS Be Used to Detect Deleterious Progression in Training Volume Among Runners?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Østergaard; Cederholm, Jens Peter; Buist, Ida;

    2013-01-01

    There is a need to ascertain if an association exists between excessive progression in weekly volume and development of running-related injuries (RRI). The purpose of this study was to investigate if GPS can be used to detect deleterious progression in weekly training volume among 60 novice runners...... included in a 10-week prospective study. All participants used GPS to quantify training volume while running. In case of injury, participants attended a clinical examination. The 13 runners who sustained injuries during follow-up had a significantly higher weekly progression in total training volume...... in the week before the injury origin (86% [95% confidence interval: 12.9-159.9], p = 0.026) compared with other weeks. Although not significant, participants with injuries had an increase in weekly training volume of 31.6% compared with a 22.1% increase among the healthy participants. The error of the GPS...

  7. 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.

  8. Ceruloplasmin decreases respiratory burst reaction during pregnancy.

    Science.gov (United States)

    Varfolomeeva, Elena Y; Semenova, Elena V; Sokolov, Alexey V; Aplin, Kirill D; Timofeeva, Kseniya E; Vasilyev, Vadim B; Filatov, Michael V

    2016-08-01

    Testing of pregnant women reveals weakening of neutrophil-mediated effector functions, such as reactive oxygen species generation. This study provides data confirming the phenomenon, gained through application of the flow cytometry technique. Key factors influencing neutrophil functional activity in blood plasma of pregnant women have not been detected so far. At the same time, concentration of ceruloplasmin - a copper-containing glycoprotein - is known to increase in blood significantly during pregnancy. We observed the negative correlation between ceruloplasmin concentration in blood plasma of pregnant women and the intensity of respiratory burst of neutrophils. Fractionation of plasma using gel-filtration revealed that ceruloplasmin-containing fraction demonstrated suppression of the respiratory burst reaction. Partial elimination of ceruloplasmin from the blood of pregnant women, performed with the help of specific antibodies and followed by immunoprecipitation, leads to an increased respiratory burst reaction. On the contrary, addition of ceruloplasmin to blood samples of healthy donors noticeably decreases the respiratory burst reaction. The results presented prove that change in ceruloplasmin level in plasma is necessary and sufficient for modulating the ability of neutrophils to produce reactive oxygen species during pregnancy.

  9. A Leptonic-Hadronic Model for the Afterglow of Gamma-Ray Burst 090510

    Science.gov (United States)

    2010-11-20

    rights reserved. Printed in the U.S.A. A LEPTONIC– HADRONIC MODEL FOR THE AFTERGLOW OF GAMMA-RAY BURST 090510 Soebur Razzaque1 Space Science Division...combined leptonic– hadronic model of synchrotron radiation from an adiabatic blast wave. High-energy, !100 MeV, emission in our model is dominated by...escape the blast wave at early time, and their detection can provide evidence of a hadronic emission component dominating at high energies. Key words

  10. Cosmic Forensics Confirms Gamma-Ray Burst And Supernova Connection

    Science.gov (United States)

    2003-03-01

    between the supernova and the gamma ray burst. The supra-nova model involves a two-step process: the first step is the collapse of the core of an extremely massive star accompanied by the ejection of the outer layers of the star. The collapsed core forms a rapidly rotating black hole surrounded by a swirling disk of matter. In the second step this black hole-disk system produces a jet of high-energy particles. Shock waves within the jet produce the burst of X-rays and gamma rays that is observed to last only a few minutes. Interaction of the jet with the ejected supernova shell produces the X-ray afterglow, which can last for days or even months. The reason for the delay between the formation of the black hole and the production of the jet is not understood. Earlier observations with Japan's ASCA, the Italian-Netherlands Beppo-SAX, and the European Space Agency's XMM-Newton satellites, as well as Chandra had given some indication of the presence of elements expected in a shell ejected by a supernova. However, the number of X-rays detected in those observations was small, and the possibility remained that the reported lines were an instrumental effect or statistical fluctuation. Since Chandra was able to observe X-ray lines from GRB 020813 for almost an entire day, the number of X-rays detected was five times larger than for previous observations. This enabled the team to make a definitive identification of the silicon and sulfur lines. Chandra observed GRB 020813 for about 77,000 seconds, approximately 21 hours after the initial burst. Other members of the research team included Herman Marshall, George Ricker, Roland Vanderspek, Peter Ford, Geoffrey Crew (MIT), and Donald Lamb (University of Chicago). The High Energy Transmission Grating Spectrometer was built by MIT. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center

  11. Can the comet assay be used reliably to detect nanoparticle-induced genotoxicity?

    Science.gov (United States)

    Karlsson, Hanna L; Di Bucchianico, Sebastiano; Collins, Andrew R; Dusinska, Maria

    2015-03-01

    The comet assay is a sensitive method to detect DNA strand breaks as well as oxidatively damaged DNA at the level of single cells. Today the assay is commonly used in nano-genotoxicology. In this review we critically discuss possible interactions between nanoparticles (NPs) and the comet assay. Concerns for such interactions have arisen from the occasional observation of NPs in the "comet head", which implies that NPs may be present while the assay is being performed. This could give rise to false positive or false negative results, depending on the type of comet assay endpoint and NP. For most NPs, an interaction that substantially impacts the comet assay results is unlikely. For photocatalytically active NPs such as TiO2 , on the other hand, exposure to light containing UV can lead to increased DNA damage. Samples should therefore not be exposed to such light. By comparing studies in which both the comet assay and the micronucleus assay have been used, a good consistency between the assays was found in general (69%); consistency was even higher when excluding studies on TiO2 NPs (81%). The strong consistency between the comet and micronucleus assays for a range of different NPs-even though the two tests measure different endpoints-implies that both can be trusted in assessing the genotoxicity of NPs, and that both could be useful in a standard battery of test methods.

  12. Phase dependency of long-term potentiation induction during the intermittent bursts of carbachol-induced β oscillation in rat hippocampal slices.

    Science.gov (United States)

    Nishimura, Motoshi; Nakatsuka, Hiroki; Natsume, Kiyohisa

    2012-01-01

    The rodent hippocampus possesses theta (θ) and beta (β) rhythms, which occur intermittently as bursts. Both rhythms are related to spatial memory processing in a novel environment. θ rhythm is related to spatial memory encoding process. β rhythm is related to the match/mismatch process. In the match/mismatch process, rodent hippocampus detects a representation matching sensory inputs of the current place among the retrieved internal representations of places. Long-term synaptic potentiation (LTP) is induced in both processes. The cholinergic agent carbachol induces intermittent θ and β oscillations in in vitro slices similar to in vivo bursts. LTP is facilitated during the generation of θ oscillation, suggesting that the facilitation of LTP is dependent upon the phases of intermittent burst (burst phases) of the oscillation. However, whether this is the case for β oscillation has not yet been studied. In the present study, LTP-inducing θ-burst stimulation was administered at the different burst phases of carbachol-induced β oscillations (CIBO), and the synaptic changes were measured at CA3-CA3 pyramidal cell synapses (CA3 synapse) and at CA3-CA1 pyramidal cell synapses (CA1 synapse). At the CA3 synapse, the largest magnitude of LTP was induced at the late burst phases of CIBO. At the CA1 synapse, LTP was induced only at the late burst phases. Modulation of LTP was suppressed when CIBO was blocked by the application of atropine at both synapses. The results suggest that the bursts of hippocampal β rhythm can determine the optimal temporal period for completing with the match/mismatch process.

  13. Bursting behaviours in cascaded stimulated Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov-Maxwell system.A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma.It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light,as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction.The bursting time in the reflectivity is found to be less than half the ion acoustic period.The ion temperature can affect the stimulated Brillouin scattering cascade,which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures.For stimulated Brillouin scattering saturation,higher-harmonic generation and wave-wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter.In addition,stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light.

  14. Exhaled flow monitoring can detect bronchial flap-valve obstruction in a mechanical lung model.

    Science.gov (United States)

    Breen, P H; Serina, E R; Barker, S J

    1995-08-01

    Flap-valve obstruction to expiratory flow (V) in a major bronchus can result from inspissated secretions, blood, or foreign body. During inhalation, increasing airway caliber preserves inspired V past the obstruction; during exhalation, decreasing airway diameter causes airflow obstruction and even frank gas trapping. We reasoned that the resultant sequential, biphasic exhalation of the lungs would be best detected by measuring exhaled V versus time. Accordingly, we designed an airway obstruction element in a mechanical lung model to examine flap-valve bronchial obstruction. A mechanical lung simulator was ventilated with a pressure-limited flow generator, where f = 10/min, tidal volume = 850 mL, and respiratory compliance = 40 mL/cm H2O. Airway V (pneumotachometer) and pressure (P) were digitally sampled for 1 min. Then, the circumference of the diaphragm in a respiratory one-way valve was trimmed to generate unidirectional resistance to expiratory V. Measurement sequences were repeated after this flap-valve was interposed in the right "main-stem bronchus." Integration of airway V versus time generated changes in lung volume. During flap-valve obstruction of the right bronchus, the V-time plot revealed preservation of peak expired flow from the normal lung, followed by retarded and decreased flow from the obstructed right lung. Gas trapping of the obstructed lung occurred during conditions of decreased expiratory time and increased expiratory resistance. Airway P could not differentiate between bronchial and tracheal flap-valve obstruction because P decreased abruptly in both conditions. The flow-volume loop displayed less distinctive changes than the flow-time plot, in part because the flow-volume loop was data (flow) plotted against its time integral (volume), with loss of temporal data. In this mechanical lung model, we conclude that bronchial flap-valve obstruction was best detected by the flow-time plot, which could measure the sequential emptying of the

  15. The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs

    CERN Document Server

    Hurley, K; Frontera, F; Montanari, E; Rossi, F; Feroci, M; Mazets, E; Golenetskii, S; Frederiks, D D; Pal'shin, V D; Aptekar, R L; Cline, T; Trombka, J; McClanahan, T; Starr, R; Atteia, J -L; Barraud, C; Pelangeon, A; Boer, M; Vanderspek, R; Ricker, G; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Boynton, W; Fellows, C; Harshman, K; Goldsten, J; Gold, R; Smith, D M; Wigger, C; Hajdas, W

    2010-01-01

    Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 787 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.

  16. Solar Partial N-burst

    Institute of Scientific and Technical Information of China (English)

    Zong-Jun Ning; Yu-Ying Liu; Qi-Jun Fu; Fu-Ying Xu

    2003-01-01

    We present a new sub-class of type III solar radio burst at the highfrequencies around 6.0 GHz. In addition to a descending and an ascending branchon the dynamic spectrum, it has an inverted morphology different from the simpletype U-burst. We call it "partial N-burst" because it is interpreted as the knownN-burst minus its first branch. The partial N-burst presented here was detectedamong a reverse slope type III (RS-III) burst group prior to the type V solar radiocontinuum and was simultaneously recorded by two spectrometers at the NationalAstronomical Observatories, Chinese Academy of Sciences (NAOC, 5.20-7.60 GHz)and at Purple Mountain Observatory (PMO, 4.50-7.50 GHz) on 1999 August 25.After the N-burst and M-burst, the partial N-burst is a third piece of evidence for amagnetic mirror effect in solar radio observation, when the same electron is reflectedat a pinched foot of a flare loop.

  17. Gamma-ray burst spectra

    Science.gov (United States)

    Teegarden, B. J.

    1982-01-01

    A review of recent results in gamma-ray burst spectroscopy is given. Particular attention is paid to the recent discovery of emission and absorption features in the burst spectra. These lines represent the strongest evidence to date that gamma-ray bursts originate on or near neutron stars. Line parameters give information on the temperature, magnetic field and possibly the gravitational potential of the neutron star. The behavior of the continuum spectrum is also discussed. A remarkably good fit to nearly all bursts is obtained with a thermal-bremsstrahlung-like continuum. Significant evolution is observed of both the continuum and line features within most events.

  18. Gamma-ray-burst beaming and gravitational-wave observations.

    Science.gov (United States)

    Chen, Hsin-Yu; Holz, Daniel E

    2013-11-01

    Using the observed rate of short-duration gamma-ray bursts (GRBs) it is possible to make predictions for the detectable rate of compact binary coalescences in gravitational-wave detectors. We show that the nondetection of mergers in the existing LIGO/Virgo data constrains the beaming angles and progenitor masses of gamma-ray bursts, although these limits are fully consistent with existing expectations. We make predictions for the rate of events in future networks of gravitational-wave observatories, finding that the first detection of a neutron-star-neutron-star binary coalescence associated with the progenitors of short GRBs is likely to happen within the first 16 months of observation, even in the case of only two observatories (e.g., LIGO-Hanford and LIGO-Livingston) operating at intermediate sensitivities (e.g., advanced LIGO design sensitivity, but without signal recycling mirrors), and assuming a conservative distribution of beaming angles (e.g., all GRBs beamed within θ(j) = 30°). Less conservative assumptions reduce the waiting time until first detection to a period of weeks to months, with an event detection rate of >/~10/yr. Alternatively, the compact binary coalescence model of short GRBs can be ruled out if a binary is not seen within the first two years of operation of a LIGO-Hanford, LIGO-Livingston, and Virgo network at advanced design sensitivity. We also demonstrate that the gravitational wave detection rate of GRB triggered sources (i.e., those seen first in gamma rays) is lower than the rate of untriggered events (i.e., those seen only in gravitational waves) if θ(j)≲30°, independent of the noise curve, network configuration, and observed GRB rate. The first detection in gravitational waves of a binary GRB progenitor is therefore unlikely to be associated with the observation of a GRB.

  19. 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...

  20. 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.

  1. X-ray bursts and superbursts - recent developments

    CERN Document Server

    Zand, Jean in 't

    2011-01-01

    The past decade and a half has seen many interesting new developments in X-ray burst research, both observationally and theoretically. New phenomena were discovered, such as burst oscillations and superbursts, and new regimes of thermonuclear burning identified. An important driver of the research with present and future instrumentation in the coming years is the pursuit of fundamental neutron star parameters. However, several other more direct questions are also in dire need of an answer. For instance, how are superbursts ignited and why do burst oscillations exist in burst tails? We briefly review recent developments and discuss the role that MAXI can play. Thanks to MAXI's large visibility window and large duty cycle, it is particularly well suited to investigate the recurrence of rare long duration bursts such as superbursts. An exploratory study of MAXI data is briefly presented.

  2. 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.

  3. X-Ray Bursts from the Transient Magnetar Candidate XTE J1810-197

    Science.gov (United States)

    Kouveliotou, Chryssa; Woods, Peter M.; Gavriil, Fotis P.; Kaspi, Victoria M.; Roberts, Mallory S. E.; Ibrahim, Alaa; Markwardt, Craig B.; Swank, Jean H.; Finger, Mark H.

    2005-01-01

    We have discovered four X-ray bursts, recorded with the Rossi X-ray Timing Explorer Proportional Counter Array between 2003 September and 2004 April, that we show to originate from the transient magnetar candidate XTE 51810-197. The burst morphologies consist of a short spike or multiple spikes lasting approx. 1 s each followed by extended tails of emission where the pulsed flux from XTE 51810-197 is significantly higher. The burst spikes are likely correlated with the pulse maxima, having a chance probability of a random phase distribution of 0.4%. The burst spectra are best fit to a blackbody with temperatures 4-8 keV, considerably harder than the persistent X-ray emission. During the X-ray tails following these bursts, the temperature rapidly cools as the flux declines, maintaining a constant emitting radius after the initial burst peak. The temporal and spectral characteristics of these bursts closely resemble the bursts seen from 1E 1048.1-5937 and a subset of the bursts detected from 1E 2259+586, thus establishing XTE J1810-197 as a magnetar candidate. The bursts detected from these three objects are sufficiently similar to one another, yet si,g&cantly differe2t from those seen from soft gamma repeaters, that they likely represent a new class of bursts from magnetar candidates exclusive (thus far) to the anomalous X-ray pulsar-like sources.

  4. Gamma-Ray Bursts Above 1 GeV

    CERN Document Server

    Baring, M G

    1997-01-01

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between sou...

  5. [Can the DGHM test for the surgical hand disinfection be used to detect residual effects?].

    Science.gov (United States)

    Gottardi, W

    1997-08-01

    It is investigated if the log reductions measured by the DGHM test for examination and evaluation of disinfecting procedures for the surgical hand wash, i.e. the short and long term values RFreference, 0h, RFreference, 3h, RFpreparation, 0h and RFpreparation, 3h can be used to detect residual effects (a remanent action) of the tested preparation. To do this the differences delta RF = RF0h-RF3h of reference and tested preparation have been formed which are a measure for the bacterial regeneration rate. A remanence index RI = magnitude of delta RFreference/magnitude of delta RFpreparation has been specified, which, in case RI > 1 indicates a residual effect of the test preparation in relation to the reference. The evaluation of 21 testing protocols is showing that the calculated remanence indexes are far away from any significance. This is attributed on the one hand to the great standard deviations of the log reductions and on the other hand to virtually only small residual effects of the tested preparations.

  6. Can the Gravity Recovery and Climate Experiment (GRACE) mission detect hydrological droughts?

    Science.gov (United States)

    Agustin Brena Naranjo, Jose; Pedrozo Acuña, Adrian

    2016-04-01

    Detecting and characterizing hydrological droughts at the global scale is a difficult task as several thousands of mid-to-large catchments remain ungauged or have limited discharge records. In water-limited regions, research on hydrological drought is even more complex because of the dominant streamflow perennial regime that characterizes small order watersheds. Over the last decade, the emergence of global remote sensing products has remarkably improved the capability to observe different climate and land surface processes that affect catchment discharge. Among several observational satellites that provide continuous data on terrestrial hydrology, the Gravity Recovery and Climate Experiment (GRACE) is perhaps the only tool able to retrieve information about large-scale water storage variations across the world's terrestrial surface. This work tests the hypothesis that water storage deficits derived from GRACE are inextricably linked to below-than-average baseflow values extracted from streamflow records. This study case analyzed several regions in Mexico and USA with different hydro-climate regimes. Drought conditions using total water storage variations and observed streamflow records from 2003 until 2013 were computed and compared. Results indicate that although the GRACE mission is moderately/highly correlated to streamflow and baseflow time series, discrepancies in the magnitude of hydrological deficit exist and can be attributed to active versus passive catchment storage issues. Finally, the suitability of creating an improved product to monitor hydrological drought by merging in situ with remote sensed information will be discussed.

  7. Can Virialization Shocks be Detected Around Galaxy Clusters Through the Sunyaev-Zel'dovich Effect?

    CERN Document Server

    Kocsis, B; Frei, Z; Kocsis, Bence; Haiman, Zoltan; Frei, Zsolt

    2004-01-01

    In cosmological structure formation models, massive non-linear objects in the process of formation, such as galaxy clusters, are surrounded by large-scale shocks at or around the expected virial radius. Direct observational evidence for such virial shocks is currently lacking, but we show here that their presence can be inferred from future, high resolution, high-sensitivity observations of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. We study the detectability of virial shocks in mock SZ maps, using simple models of cluster structure (gas density and temperature distributions) and noise (background and foreground galaxy clusters projected along the line of sight, as well as the cosmic microwave background anisotropies). We find that at an angular resolution of 2'' and sensitivity of 10 micro K, expected to be reached at ~ 100 GHz frequencies in a ~ 20 hr integration with the forthcoming ALMA instrument, virial shocks associated with massive M ~ 10^15 M_Sun clusters will stand out from the noise, an...

  8. Biofilm detection by wound blotting can predict slough development in pressure ulcers: A prospective observational study.

    Science.gov (United States)

    Nakagami, Gojiro; Schultz, Gregory; Gibson, Daniel J; Phillips, Priscilla; Kitamura, Aya; Minematsu, Takeo; Miyagaki, Tomomitsu; Hayashi, Akitatsu; Sasaki, Sanae; Sugama, Junko; Sanada, Hiromi

    2016-12-26

    Bacteria have been found to form multicellular aggregates which have collectively been termed "biofilms." It is hypothesized that biofilm formation is a means to protect bacterial cells including protection form the immune response of humans. This protective mechanism is believed to explain persistent chronic wound infections. At times, the biofilms are abundant enough to see, and remove by simple wiping. However, recent evidence has shown that the removal of these visible portions are not sufficient, and that biofilms can continue to form even with daily wiping. In this work, we tested an approach to detect the biofilms which are present after clinically wiping or sharp wound debridement. Our method is based on a variation of impression cytology in which a nitrocellulose membrane was used to collect surface biofilm components, which were then differentially stained. In this prospective study, members of an interdisciplinary pressure ulcer team at a university hospital tested our method's ability to predict the generation of wound slough in the week that followed each blotting. A total of 70 blots collected from 23 pressure ulcers produced 27 wounds negative for staining and 43 positive. In the negative blots 55.6% were found to have decreased wound slough, while 81.4% with positive staining had either increase or unchanged wound slough generation. These results lead to an odds ratio of positive blotting cases of 9.37 (95% confidence intervals: 2.47-35.5, p = 0.001) for slough formation; suggesting that the changes in wound slough formation can be predicted clinically using a non-invasive wound blotting method.

  9. On the Galactic Distribution of Gamma Ray Bursts

    CERN Document Server

    Lewin, W H G; Lewin, Robert E. Rutledge \\& Walter H.G.

    1993-01-01

    Quashnock and Lamb (1993) defined a sub-sample of Gamma-ray Bursts (GRBs) from the publicly available BATSE database which shows clumping toward the galactic plane, and concluded that all GRBs are galactic in origin. The selection of these bursts (duplicated in this work in Sample 1) involved a peak countrate (in counts s-1) uncorrected for aspect. We assert that the peak flux of a burst is physically more meaningful than peak count-rate. Using, as limits, the corresponding peak fluxes (in photons cm-2 s-1) for the bursts in the QL sample, we find an additional 24 bursts, which we include in a new sample (Sample 2). We find that the significance of anisotropy in Sample 2 is much less than that of Sample 1, which does not support QL's interpretation of the anisotropies as being due to a galactic population. To make meaningful statistical statements regarding isotropy, burst samples must have peak fluxes above a minimum flux, set by the requirement that a burst be detectable from any direction (above the horizo...

  10. 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.

  11. Can Mismatch Negativity Be Linked to Synaptic Processes? A Glutamatergic Approach to Deviance Detection

    Science.gov (United States)

    Strelnikov, Kuzma

    2007-01-01

    This article aims to provide a theoretical framework to elucidate the neurophysiological underpinnings of deviance detection as reflected by mismatch negativity. A six-step model of the information processing necessary for deviance detection is proposed. In this model, predictive coding of learned regularities is realized by means of long-term…

  12. The Gap Detection Test : Can It Be Used to Diagnose Tinnitus?

    NARCIS (Netherlands)

    Boyen, Kris; Başkent, Deniz; van Dijk, Pim

    2015-01-01

    Objectives: Animals with induced tinnitus showed difficulties in detecting silent gaps in sounds, suggesting that the tinnitus percept may be filling the gap. The main purpose of this study was to evaluate the applicability of this approach to detect tinnitus in human patients. The authors first hyp

  13. Transient optical emission from the error box of the gamma-ray burst of 28 February 1997

    DEFF Research Database (Denmark)

    van Paradijs, J.; Groot, P.J.; Galama, T.;

    1997-01-01

    For almost a quarter of a century(1), the origin of gamma-ray bursts-brief, energetic bursts of high-energy photons-has remained unknown. The detection of a counterpart at another wavelength has long been thought to be a key to understanding the nature of these bursts (see, for example, ref. 2), ...

  14. Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Altamirano, Diego; Galloway, Duncan

    2010-01-01

    We investigate the thermonuclear bursting behaviour of IGR J17473−2721, an X-ray transient that in 2008 underwent a 6-month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, Rossi X-ray Timing Explore...

  15. An accretion disk swept up by a powerful thermonuclear X-ray burst

    Science.gov (United States)

    Degenaar, Nathalie

    Type-I X-ray bursts are thermonuclear explosions occurring in the surface layers of accreting neutron stars. These events are powerful probes of the physics of neutron stars and their surrounding accretion flow. Swift recently caught a very energetic type-I X-ray burst from the neutron star IGR J17062-6143 that displayed exceptional features. Firstly, the light curve of the 18 minute long X-ray burst tail shows an episode of 10 minutes with wild X-ray intensity fluctuations. Secondly, X-ray spectral analysis revealed a highly significant emission line around 1 keV, which can be interpreted as an Fe-L shell line caused by the irradiation of cold gas. Finally, the detection of significant absorption lines and edges in the Fe-K band are strongly suggestive of the presence of hot, highly ionized gas along the line of sight. None of these features are present in the persistent emission of the source. The X-ray burst of IGR J17062-6143 shows the first unambiguous detection of atomic features at CCD resolution. The timescale of the strong intensity variations, the velocity width of the Fe-L emission line, and photo-ionization modeling of the Fe-K absorption features each independently point to swept-up gas at a radius of ~1000 km from the neutron star. The unusual X-ray light curve and spectral properties could have plausibly been caused by a disruption of the accretion disk due to the super-Eddington fluxes reached during the X-ray burst.

  16. A search for dispersed radio bursts in archival Parkes Multibeam Pulsar Survey data

    CERN Document Server

    Bagchi, Manjari; McLaughlin, Maura

    2012-01-01

    A number of different classes of potentially extra-terrestrial bursts of radio emission have been observed in surveys with the Parkes 64m radio telescope, including "Rotating Radio Transients", the "Lorimer burst" and "perytons". Rotating Radio Transients are radio pulsars which are best detectable in single-pulse searches. The Lorimer burst is a highly dispersed isolated radio burst with properties suggestive of extragalactic origin. Perytons share the frequency-swept nature of the Rotating Radio Transients and Lorimer burst, but unlike these events appear in all thirteen beams of the Parkes Multibeam receiver and are probably a form of peculiar radio frequency interference. In order to constrain these and other radio source populations further, we searched the archival Parkes Multibeam Pulsar Survey data for events similar to any of these. We did not find any new Rotating Radio Transients or bursts like the Lorimer burst. We did, however, discover four peryton-like events. Similar to the perytons, these fou...

  17. The Synergy of Gamma-Ray Burst Detectors in the GLAST Era

    Science.gov (United States)

    Band, David

    2008-01-01

    Simultaneous observations by the large number of gamma-ray burst detectors that will operate in the GLAST era will provide the spectra, lightcurves and locations necessary for studying burst physics and testing the putative relations between intrinsic burst properties. I review the burst detection sensitivities, spectral bands, and localization capabilities of the GLAST (GBM and LAT), Swift (BAT), INTEGRAL (ISGRI), Suzaku (wAM), AGILE (Super-AGILE) and wind (Konus) detectors; the detectors' energy band and the accumulation timescale of their trigger system affect their sensitivity to hard vs. soft and long vs. short bursts. In addition, I estimate the rate of simultaneous burst observations. In particular, coordination of the Swift observing plan consistent with Swift's other science objectives could increase the rate of GLAST bursts with redshifts

  18. 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.

  19. Neuronal networks and energy bursts in epilepsy.

    Science.gov (United States)

    Wu, Y; Liu, D; Song, Z

    2015-02-26

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

  20. Cleaved PARP-1, an Apoptotic Marker, can be Detected in Ram Spermatozoa.

    Science.gov (United States)

    Casao, A; Mata-Campuzano, M; Ordás, L; Cebrián-Pérez, J A; Muiño-Blanco, T; Martínez-Pastor, F

    2015-08-01

    The presence of apoptotic features in spermatozoa has been related to lower quality and functional impairment. Members of the poly-ADP-ribose polymerases (PARP) familyare involved in both DNA repair and apoptosis, playing important roles in spermatogenesis. Poly-ADP-ribose polymerase can be cleaved by caspases, and the presence of its cleavage product (cPARP) in spermatozoa has been related to chromatin remodelling during spermatogenesis and to the activation of apoptotic pathways. There are no reports on immunodetection of cPARP in ram spermatozoa; thus, we have tested a commercially available antibody for this purpose. cPARP was microscopically detected in the acrosomal ridge of some spermatozoa (indirect immunofluorescence). A preliminary study was carried out by flow cytometry (direct immunofluorescence, FITC). Ram semen was extended in TALP and incubated for 4 h with apoptosis inducers staurosporine (10 μm) or betulinic acid (200 μm). Both inducers and incubation caused a significant increase in cPARP spermatozoa (0 h, control: 21.4±3.3%, inducers: 44.3±1.4%; 4 h, control: 44.3±2.4%, inducers: 53.3±1.4%). In a second experiment, we compared the sperm fractions after density gradient separation (pellet and interface). The pellet yielded a slightly lower proportion of cPARP spermatozoa (28.5±1.2% vs 36.2±2.0% in the interface; p ram semen, although its presence in untreated samples was weakly related to worse quality (pellet/interface). We suggest to study the relationship of PARP and cPARP levels with between-male differences on sperm fertility.

  1. Radio Bursts with Extragalactic Spectral Characteristics Show Terrestrial Origins

    CERN Document Server

    Burke-Spolaor, Sarah; Ekers, Ronald; Macquart, Jean-Pierre; Crawford, Fronefield

    2010-01-01

    Three years ago, the report of a solitary radio burst was thought to be the first discovery of a rare, impulsive event of unknown extragalactic origin (Lorimer et al. 2007). The extragalactic interpretation was based on the swept-frequency nature of the event, which followed the dispersive delay expected from an extragalactic pulse. We report here on the detection of 16 pulses, the bulk of which exhibit a frequency sweep with a shape and magnitude resembling the Lorimer Burst. These new events were detected in a sidelobe of the Parkes Telescope and are of clearly terrestrial origin, with properties unlike any known sources of terrestrial broad-band radio emission. The new detections cast doubt on the extragalactic interpretation of the original burst, and call for further sophistication in radio-pulse survey techniques to identify the origin of the anomalous terrestrial signals and definitively distinguish future extragalactic pulse detections from local signals. The ambiguous origin of these seemingly disper...

  2. Short Gamma-Ray Bursts with Extended Emission

    Science.gov (United States)

    Norris, J. P.; Bonnell, J. T.

    2005-01-01

    The recent association of several short gamma-ray bursts (GRBs) with early type galaxies with low star formation rate demonstrates that short bursts arise from a different progenitor mechanism than long bursts. However, since the duration distributions of the two classes overlap, membership is not always easily established. The picture is complicated by the occasional presence of softer, extended emission lasting tens of seconds after the initial spike- like emission comprising an otherwise short burst. Using the large BATSE sample with time-tagged event (TTE) data, we show that the fundamental defining characteristic of the short burst class is that the initial spike exhibits negligible spectral evolution at energies above approx. 25 keV. This is behavior is nearly ubiquitous for the 260 bursts with T(sub 90) less than 2s where the BATSE TTE data type completely included the initial spike: Their spectral lags measured between the 25-50 keV and 100-300 energy ranges are consistent with zero in 90-95% of the cases, with most outliers probably representing the tail of the long burst class. We also analyze a small sample of "short" BATSE bursts - those with the most fluent, intense extended emission. The same lack of evolution on the pulse timescale obtains for the extended emission in the brighter bursts where significant measurements can be made. One possible inference is that both emission components may arise in the same region. We also show that the dynamic range in the ratio of peak intensities, spike : extended, is at least approx. l0(exp 3), and that for some bursts, the extended emission is only a factor of 2-5 lower. However, for our whole sample the total counts fluence of the extended component equals or exceeds that in the spike by a factor of several.

  3. Inverse period-doubling bifurcations determine complex structure of bursting in a one-dimensional non-autonomous map.

    Science.gov (United States)

    Han, Xiujing; Chen, Zhenyang; Bi, Qinsheng

    2016-02-01

    We propose a simple one-dimensional non-autonomous map, in which some novel bursting patterns (e.g., "fold/double inverse flip" bursting, "fold/multiple inverse flip" bursting, and "fold/a cascade of inverse flip" bursting) can be observed. Typically, these bursting patterns exhibit complex structures containing a chain of inverse period-doubling bifurcations. The active states related to these bursting can be period-2(n) (n = 1, 2, 3,…) attractors or chaotic attractors, which may evolve to quiescence by a chain of inverse period-doubling bifurcations when the slow excitation decreases through period-doubling bifurcation points of the map. This accounts for the complex inverse period-doubling bifurcation structures observed in bursting patterns. Our findings enrich the possible routes to bursting as well as the underlying mechanisms of bursting.

  4. Can Detectability Analysis Improve the Utility of Point Counts for Temperate Forest Raptors?

    Science.gov (United States)

    Temperate forest breeding raptors are poorly represented in typical point count surveys because these birds are cryptic and typically breed at low densities. In recent years, many new methods for estimating detectability during point counts have been developed, including distanc...

  5. Can fully automated detection of corticospinal tract damage be used in stroke patients?

    OpenAIRE

    Leff, Alexander P.; Seghier, Mohamed L.; Kou, Nancy; Park, Chang-hyun; Ward, Nick S.

    2013-01-01

    We compared manual infarct definition, which is time-consuming and open to bias, with an automated abnormal tissue detection method in measuring corticospinal tract-infarct overlap volumes in chronic stroke patients to help predict motor outcome.

  6. BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550-5418 BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lin Lin; Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I Tuzla, Istanbul 34956 (Turkey); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander; Watts, Anna L. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Gruber, David; Von Kienlin, Andreas [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85748 Garching bei Mnchen (Germany); Younes, George [USRA, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, Neil, E-mail: linlin@sabanciuniv.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  7. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    Science.gov (United States)

    Lin, Lin; Goegues, Ersin; Baring, Matthew G.; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L.; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  8. Bursts de raios gama

    Science.gov (United States)

    Braga, J.

    2003-02-01

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

  9. Species detection and individual assignment in species delimitation: can integrative data increase efficacy?

    Science.gov (United States)

    Edwards, Danielle L; Knowles, L Lacey

    2014-02-22

    Statistical species delimitation usually relies on singular data, primarily genetic, for detecting putative species and individual assignment to putative species. Given the variety of speciation mechanisms, singular data may not adequately represent the genetic, morphological and ecological diversity relevant to species delimitation. We describe a methodological framework combining multivariate and clustering techniques that uses genetic, morphological and ecological data to detect and assign individuals to putative species. Our approach recovers a similar number of species recognized using traditional, qualitative taxonomic approaches that are not detected when using purely genetic methods. Furthermore, our approach detects groupings that traditional, qualitative taxonomic approaches do not. This empirical test suggests that our approach to detecting and assigning individuals to putative species could be useful in species delimitation despite varying levels of differentiation across genetic, phenotypic and ecological axes. This work highlights a critical, and often overlooked, aspect of the process of statistical species delimitation-species detection and individual assignment. Irrespective of the species delimitation approach used, all downstream processing relies on how individuals are initially assigned, and the practices and statistical issues surrounding individual assignment warrant careful consideration.

  10. High-energy emission from bright gamma-ray bursts using Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Bissaldi, Elisabetta

    2010-05-25

    mainly based on the brightest bursts detected by GBM inside the LAT field-of-view. The determination of a consistent sample for upper-limit calculations can be established by selecting those bursts which have a strong signal in the GBM BGO detectors. The structure of this thesis can be summarized as follows: The first chapter introduces the basic concepts and scientific background of GRB physics. Afterwards, instrumental details about the Fermi instruments LAT and GBM, as well as LAT performance and capabilities for GRB science are presented in chapter 2. Chapter 3 focuses on the detector-level calibration of the GBM instrument, and in particular on the analysis methods and results, which crucially support the development of a consistent GBM instrument response. The main GBM scientific results collected during the first year of operation are then presented in chapter 4. Particular emphasis is given to the description of joint GBM-LAT and GBM-Swift observations and analysis results. The last chapter presents the selection methodology and detailed spectral analysis of a sample of well-defined BGO-bright bursts detected by GBM during its first year. Using these results, correlations among spectral parameters are finally discussed. (orig.)

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

    DEFF Research Database (Denmark)

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

    1994-01-01

    The first WATCH/GRANAT Gamma‐Ray Burst Catalogue comprises 70 events which have been detected by WATCH during the period December 1989–September 1992. 32 GRBs could be localized within a 3σ error radii of 1°. We have found a weak (2.2σ) clustering of these 32 bursts towards the Galactic Center....... However we conclude that there is no strong evidence of concentration of the bursts towards the Galactic Center or Plane. Around ∼10% of the 70 bursts showed x‐ray precursor or/and X‐ray tail. We discuss the possibility that two events, GRB 900126 and GRB 920311, would have been produced by the same...

  12. Detecting 3D vegetation structure with the Galileo space probe: Can a distant probe detect vegetation structure on Earth?

    CERN Document Server

    Doughty, Christopher E

    2016-01-01

    Sagan et al. (1993) used the Galileo space probe data and first principles to find evidence of life on Earth. Here we ask whether Sagan et al. (1993) could also have detected whether life on Earth had three-dimensional structure, based on the Galileo space probe data. We reanalyse the data from this probe to see if structured vegetation could have been detected in regions with abundant photosynthetic pigments through the anisotropy of reflected shortwave radiation. We compare changing brightness of the Amazon forest (a region where Sagan et al. (1993) noted a red edge in the reflectance spectrum, indicative of photosynthesis) as the planet rotates to a common model of reflectance anisotropy and found measured increase of surface reflectance of 0.019 versus a 0.007 predicted from only anisotropic effects. We hypothesize the difference was due to minor cloud contamination. However, the Galileo dataset had only a small change in phase angle (sun-satellite position) which reduced the observed anisotropy signal an...

  13. MAXI observations of long X-ray bursts

    Science.gov (United States)

    Serino, Motoko; Iwakiri, Wataru; Tamagawa, Toru; Sakamoto, Takanori; Nakahira, Satoshi; Matsuoka, Masaru; Yamaoka, Kazutaka; Negoro, Hitoshi

    2016-12-01

    We report nine long X-ray bursts from neutron stars, detected with the Monitor of All-sky X-ray Image (MAXI). Some of these bursts lasted for hours, and hence are qualified as superbursts, which are prolonged thermonuclear flashes on neutron stars and are relatively rare events. MAXI observes roughly 85% of the whole sky every 92 minutes in the 2-20 keV energy band, and has detected nine bursts with a long e-folding decay time, ranging from 0.27 to 5.2 hr, since its launch in 2009 August until 2015 August. The majority of the nine events were found to originate from transient X-ray sources. The persistent luminosities of the sources, when these prolonged bursts were observed, were lower than 1% of the Eddington luminosity for five of them and lower than 20% for the rest. This trend is contrastive to the 18 superbursts observed before MAXI, all but two of which originated from bright persistent sources. The distribution of the total emitted energy, i.e., the product of e-folding time and luminosity, of these bursts clusters around 1041-1042 erg, whereas both the e-folding time and luminosity ranges for an order of magnitude. Among the nine events, two were from 4U 1850-086 during phases of relatively low persistent flux, whereas it usually exhibits standard short X-ray bursts during outbursts.

  14. Testing the E(sub peak)-E(sub iso) Relation for GRBs Detected by Swift and Suzaku-WAM

    Science.gov (United States)

    Krimm, H. A.; Yamaoka, K.; Sugita, S.; Ohno, M.; Sakamoto, T.; Barthelmy, S. D.; Gehrels, N.; Hara, R.; Onda, K.; Sato, G.; Tanaka, H.; Tashiro, M.; Yamauchi, M.; Norris, J. P.; Ohmori, N.

    2009-01-01

    One of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy (E(sub peak)) of the nuF(nu) spectrum and the isotropic radiated energy, E(sub iso). Since most gamma-ray bursts (GRBs) have E(sub peak) above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate E(sub peak) values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected ; one can accurately fit E(sub peak) and E(sub iso) and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of March 2009, there were 45 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 47 bursts which triggered Swift and were detected by WAM, but did not trigger. A BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters. For those bursts with spectroscopic redshifts.. we can also calculate the isotropic energy. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 86 of the bursts detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift, bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.

  15. Selecting an acceptable and safe antibody detection test can present a dilemma.

    Science.gov (United States)

    Combs, M R; Bredehoeft, S J

    2001-01-01

    The Transfusion Service at Duke University Hospital has changed antibody detection methods from the use of albumin in indirect antiglobulin tests to low-ionic-strength solution (LISS), and from LISS to polyethylene glycol (PEG) in an effort to enhance the rapid detection of clinically significant antibodies. In 1996, staffing issues required the consideration of automation. Although previous studies indicated that the gel test was not as sensitive as PEG for detection of clinically significant antibodies, we chose to implement the gel test to be used with the Tecan MegaFlex-ID. We performed a retrospective analysis of identified antibodies and transfusion reactions to compare the outcomes of one year's experience with gel and PEG. We found comparable detection of potentially clinically significant antibodies by both methods and significantly fewer unwanted or clinically insignificant antibodies detected with the use of gel. Fewer delayed serologic transfusion reactions and no transfusion-associated hemolytic events occurred in the year that gel was used. Although we initially found the selection of the gel test to be a dilemma, our ultimate decision appears to have successfully protected patient safety and balanced sensitivity with specificity.

  16. Mergers of Charged Black Holes: Gravitational-wave Events, Short Gamma-Ray Bursts, and Fast Radio Bursts

    Science.gov (United States)

    Zhang, Bing

    2016-08-01

    The discoveries of GW150914, GW151226, and LVT151012 suggest that double black hole (BH-BH) mergers are common in the universe. If at least one of the two merging black holes (BHs) carries a certain amount of charge, possibly retained by a rotating magnetosphere, the inspiral of a BH-BH system would drive a global magnetic dipole normal to the orbital plane. The rapidly evolving magnetic moment during the merging process would drive a Poynting flux with an increasing wind power. The magnetospheric activities during the final phase of the merger would make a fast radio burst (FRB) if the BH charge can be as large as a factor of \\hat{q}˜ ({10}-9{--}{10}-8) of the critical charge Q c of the BH. At large radii, dissipation of the Poynting flux energy in the outflow would power a short-duration high-energy transient, which would appear as a detectable short-duration gamma-ray burst (GRB) if the charge can be as large as \\hat{q}˜ ({10}-5{--}{10}-4). The putative short GRB coincident with GW150914 recorded by Fermi GBM may be interpreted with this model. Future joint GW/GRB/FRB searches would lead to a measurement or place a constraint on the charges carried by isolate BHs.

  17. X-ray burst induced spectral variability in 4U 1728-34

    CERN Document Server

    Kajava, J J E; Kuulkers, E; Poutanen, J

    2016-01-01

    Aims. INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time INTEGRAL has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, a.k.a. "the slow burster". Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods. We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results. We constructed a hardness intensity diagram to track spectral state variations. In the soft state the energy spectra are characterized by two thermal components - likely from the accretion disc and the boundary/spreading layer - together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an addit...

  18. Focused study of thermonuclear bursts on neutron stars

    DEFF Research Database (Denmark)

    Chenevez, Jérôme

    2009-01-01

    radius expansion bursts likely eject nuclear burning ashes into the interstellar medium, and may make possible the detection of photoionization edges. Indeed, theoretical models predict that absorption edges from 58Fe at 9.2 keV, 60Zn and 62Zn at 12.2 keV should be detectable by the future missions...

  19. Statistical properties of SGR 1900+14 bursts

    NARCIS (Netherlands)

    Göğüş, E.; Woods, P.M.; Kouveliotou, C.; van Paradijs, J.; Briggs, M.S.; Duncan, R.C.; Thompson, C.

    1999-01-01

    We study the statistics of soft gamma repeater (SGR) bursts using a database of 187 events detected with BATSE and 837 events detected with the Rossi X-Ray Timing Explorer Proportional Counter Array; all events are from SGR 1900+14 during its 1998-1999 active phase. We find that the fluence or energ

  20. Probing thermonuclear flame spreading on neutron stars using burst rise oscillations

    Science.gov (United States)

    Chakraborty, Manoneeta; Bhattacharyya, Sudip

    2016-07-01

    Intense X-ray bursts (type-I bursts), originated from runaway thermonuclear processes, are observed from the surfaces of many accreting neutron star Low Mass X-ray Binary (LMXB) systems and they provide an important tool to constrain the neutron star equation of state. Periodic intensity variations during these bursts, termed burst oscillations, are observed in about 10% of thermonuclear bursts. Oscillations during the rising phases of thermonuclear bursts are hypothesized to originate from an expanding hot-spot on the surface of the neutron star. We studied the evolution of oscillations during the rising phase of a large sample of thermonuclear bursts from 10 bursting neutron stars in order to probe the process of burning front propagation during an X-ray burst. Our results show observational evidences of expanding hot-spot with spin modulated flame speeds, possibly due to the effects of the Coriolis force present as a result of the high stellar spin (270-620 Hz). This implies that the flame propagation is latitude-dependent and we address the factors affecting the detection and non-detection of burst rise oscillations in the light of this Coriolis force modulated flame spreading scenario.

  1. Acoustic characteristics of bubble bursting at the surface of a high-viscosity liquid

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Bo; Zhang Jian-Run; Li Pu

    2012-01-01

    An acoustic pressure model of bubble bursting is proposed.An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported.It is found that the sudden bursting of a bubble at the high-viscosity liquid surface generates N-shape wave at first,then it transforms into a jet wave.The fundamental frequency of the acoustic signal caused by the bursting bubble decreases linearly as the bubble size increases.The results of the investigation can be used to understand the acoustic characteristics of bubble bursting.

  2. Hanging-induced burst suppression pattern in EEG

    Directory of Open Access Journals (Sweden)

    Nilgun Cinar

    2012-01-01

    Full Text Available Lethal suspension (hanging is one of the most common methods of attempting suicide. Spinal fractures, cognitive and motor deficits as well as epileptic seizures can be detected after unsuccessful hanging attempts. Introduced here is the case of a 25-year-old man exemplifying the clinical observations stated hereafter, who was conveyed to our emergency room after having survived attempted suicide by hanging, with his post-anoxic burst-suppression electroencephalography (BS-EEG pattern and clinical diagnoses in the post-comatose stage. The patient′s state of consciousness was gradually improved over a period of time. His neuropsychiatric assessment proved that memory deficit, a slight lack of attention and minor executive dysfunction was observed a month after the patient was discharged. Although the BS-EEG pattern indicates severe brain dysfunction, it is a poor prognostic factor; rarely, patients survive with minor cognitive deficits and can perform their normal daily activities.

  3. Understanding Neutron Stars using Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, S.

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star = EOS model of high density cold matter in the neutron star cores. Extensive observation and analysis of the data from the rising portions of the bursts = modeling of burst oscillations and thermonuclear flame spreading. Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  4. Neutron Stars and Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, Sudip

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star approaching EOS model of high density cold matter in the neutron star cores. +k Extensive observation and analysis of the data from the rising portions of the bursts - modeling of burst oscillations and thermonuclear flame spreading. +k Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  5. ESTIMATION OF BURSTS LENGTH AND DESIGN OF A FIBER DELAY LINE BASED OBS ROUTER

    Directory of Open Access Journals (Sweden)

    RICHA AWASTHI

    2017-03-01

    Full Text Available The demand for higher bandwidth is increasing day by day and this ever growing demand cannot be catered to with current electronic technology. Thus new communication technology like optical communication needs to be used. In the similar context OBS (optical burst switching is considered as next generation data transfer technology. In OBS information is transmitted in forms of optical bursts of variable lengths. However, contention among the bursts is a major problem in OBS system, and for contention resolution defection routing is mostly preferred. However, deflection routing increases delay. In this paper, it is shown that the arrival of very large bursts is rare event, and for moderate burst length the buffering of contending burst can provide very effective solution. However, in case of arrival of large bursts deflection can be used.

  6. Image-guided diagnosis of prostate cancer can increase detection of tumors

    Science.gov (United States)

    In the largest prospective study to date of image-guided technology for identifying suspicious regions of the prostate to biopsy, researchers compared the ability of this technology to detect high-risk prostate cancer with that of the current standard of

  7. Can parents detect 8- to 16-year-olds' lies? Parental biases, confidence, and accuracy.

    Science.gov (United States)

    Evans, Angela D; Bender, Jasmine; Lee, Kang

    2016-07-01

    Honesty is a crucial aspect of a trusting parent-child relationship. Given that close relationships often impair our ability to detect lies and are related to a truth bias, parents may have difficulty with detecting their own children's lies. The current investigation examined the lie detection abilities (accuracy, biases, and confidence) of three groups of participants: non-parent group (undergraduates), parent-other group (parents who evaluated other peoples' children's statements), and parent-own group (parents who evaluated their own children's statements). Participants were presented with videos of 8- to 16-year-olds telling either the truth or a lie about having peeked at the answers to a test and were asked to evaluate the veracity of the statement along with their confidence in their judgment. All groups performed at chance in the accuracy of their veracity judgments. Furthermore, although all groups tended to hold a truth bias for 8- to 16-year-olds, the parent-own group held a much stronger truth bias than the other two groups. All groups were also highly confident in their judgments (70%-76%), but confidence ratings failed to predict accuracy. These findings, taken together, suggest that the close relationship that parents share with their own children may be related to a bias toward believing their children's statements and, hence, a failure to detect their lies.

  8. Can Children with SLI Detect Cognitive Conflict? Behavioral and Electrophysiological Evidence

    Science.gov (United States)

    Epstein, Baila; Shafer, Valerie L.; Melara, Robert D.; Schwartz, Richard G.

    2014-01-01

    Purpose: This study examined whether children with specific language impairment (SLI) are deficient in detecting cognitive conflict between competing response tendencies in a GO/No-GO task. Method: Twelve children with SLI (ages 10--12), 22 children with typical language development matched group-wise on age (TLD-A), and 16 younger children with…

  9. Caries detection methods : Can they aid decision making for invasive sealant treatment?

    NARCIS (Netherlands)

    Pereira, AC; Verdonschot, EH; Huysmans, MCDNJM

    2001-01-01

    The decision to place sealants is a difficult one, and it has been suggested that in a low risk population it may be efficient to wait until caries is detected in the fissure. An invasive sealant technique with fissure preparation may then be indicated. The diagnostic method used in the indication o

  10. Rock burst laws in deep mines based on combined model of membership function and dominance-based rough set

    Institute of Scientific and Technical Information of China (English)

    刘浪; 陈忠强; 王李管

    2015-01-01

    Rock bursts are spontaneous, violent fracture of rock that can occur in deep mines, and the likelihood of rock bursts occurring increases as depth of the mine increases. Rock bursts are also affected by the compressive strength, tensile strength, tangential strength, elastic energy index, etc. of rock, and the relationship between these factors and rock bursts in deep mines is difficult to analyze from quantitative point. Typical rock burst instances as a sample set were collected, and membership function was introduced to process the discrete values of these factors with the discrete factors as condition attributes and rock burst situations as decision attributes. Dominance-based rough set theory was used to generate preference rules of rock burst, and eventually rock burst laws analysis in deep mines with preference relation was taken. The results show that this model for rock burst laws analysis in deep mines is more reasonable and feasible, and the prediction results are more scientific.

  11. 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.

  12. 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...

  13. Radio fiber bursts and fast magnetoacoustic wave trains

    CERN Document Server

    Karlický, M; Jelínek, P

    2012-01-01

    We present a model for dm-fiber bursts that is based on assuming fast sausage magnetoacoustic wave trains that propagate along a dense vertical filament or current sheet. Eight groups of dm-fiber bursts that were observed during solar flares were selected and analyzed by the wavelet analysis method. To model these fiber bursts we built a semi-empirical model. We also did magnetohydrodynamic simulations of a propagation of the magnetoacoustic wave train in a vertical and gravitationally stratified current sheet. In the wavelet spectra of the fiber bursts computed at different radio frequencies we found the wavelet tadpoles, whose head maxima have the same frequency drift as the drift of fiber bursts. It indicates that the drift of these fiber bursts can be explained by the propagating fast sausage magnetoacoustic wave train. Using new semi-empirical and magnetohydrodynamic models with a simple radio emission model we generated the artificial radio spectra of the fiber bursts, which are similar to the observed ...

  14. Behaviorally relevant burst coding in primary sensory neurons.

    Science.gov (United States)

    Sabourin, Patrick; Pollack, Gerald S

    2009-08-01

    Bursts of action potentials in sensory interneurons are believed to signal the occurrence of particularly salient stimulus features. Previous work showed that bursts in an identified, ultrasound-tuned interneuron (AN2) of the cricket Teleogryllus oceanicus code for conspicuous increases in amplitude of an ultrasound stimulus, resulting in behavioral responses that are interpreted as avoidance of echolocating bats. We show that the primary sensory neurons that inform AN2 about high-frequency acoustic stimuli also produce bursts. As is the case for AN2, bursts in sensory neurons perform better as feature detectors than isolated, nonburst, spikes. Bursting is temporally correlated between sensory neurons, suggesting that on occurrence of a salient stimulus feature, AN2 will receive strong synaptic input in the form of coincident bursts, from several sensory neurons, and that this might result in bursting in AN2. Our results show that an important feature of the temporal structure of interneuron spike trains can be established at the earliest possible level of sensory processing, i.e., that of the primary sensory neuron.

  15. 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...

  16. 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.

  17. How Soft Gamma Repeaters Might Make Fast Radio Bursts

    Science.gov (United States)

    Katz, J. I.

    2016-08-01

    There are several phenomenological similarities between soft gamma repeaters (SGRs) and fast radio bursts (FRBs), including duty factors, timescales, and repetition. The sudden release of magnetic energy in a neutron star magnetosphere, as in popular models of SGRs, can meet the energy requirements of FRBs, but requires both the presence of magnetospheric plasma, in order for dissipation to occur in a transparent region, and a mechanism for releasing much of that energy quickly. FRB sources and SGRs are distinguished by long-lived (up to thousands of years) current-carrying coronal arches remaining from the formation of the young neutron star, and their decay ends the phase of SGR/AXP/FRB activity even though “magnetar” fields may persist. Runaway increases in resistance when the current density exceeds a threshold, releases magnetostatic energy in a sudden burst, and produces high brightness GHz emission of FRB by a coherent process. SGRs are produced when released energy thermalizes as an equlibrium pair plasma. The failures of some alternative FRB models and the non-detection of SGR 1806-20 at radio frequencies are discussed in the appendices.

  18. Fast Radio Bursts with Extended Gamma-Ray Emission?

    CERN Document Server

    Murase, Kohta; Fox, Derek B

    2016-01-01

    We consider some general implications of bright gamma-ray counterparts to fast radio bursts (FRBs). We show that, even if these manifest in only a fraction of FRBs, gamma-ray detections with current satellites (including Swift) provide stringent constraints on cosmological FRB models. If the energy is drawn from the magnetic energy of a compact object such as a magnetized neutron star, the sources should be nearby and very rare. If the intergalactic medium is responsible for the observed dispersion measure, the required gamma-ray energy is comparable to that of the early afterglow or extended emission of short gamma-ray bursts. While this can be reconciled with the rotation energy of compact objects, as expected in many merger scenarios, the prompt outflow that yields the gamma-rays is too dense for radio waves to escape. Highly-relativistic winds launched in a precursor phase, and forming a wind bubble, may avoid the scattering and absorption limits and could yield FRB emission. Largely independent of source...

  19. Calibration of Gamma-ray Burst Polarimeter POLAR

    CERN Document Server

    Xiao, H L; Bao, T W; Batsch, T; Bernasconi, T; Cernuda, I; Chai, J Y; Dong, Y W; Gauvin, N; Kole, M; Kong, M N; Kong, S W; Li, L; Liu, J T; Liu, X; Marcinkowski, R; Orsi, S; Pohl, M; Produit, N; Rapin, D; Rutczynska, A; Rybka, D; Shi, H L; Song, L M; Sun, J C; Szabelski, J; Wu, B B; Wang, R J; Wen, X; Xu, H H; Zhang, L; Zhang, L Y; Zhang, S N; Zhang, X F; Zhang, Y J; Zwolinska, A

    2015-01-01

    Gamma Ray Bursts (GRBs) are the strongest explosions in the universe which might be associated with creation of black holes. Magnetic field structure and burst dynamics may influence polarization of the emitted gamma-rays. Precise polarization detection can be an ultimate tool to unveil the true GRB mechanism. POLAR is a space-borne Compton scattering detector for precise measurements of the GRB polarization. It consists of a 40$\\times$40 array of plastic scintillator bars read out by 25 multi-anode PMTs (MaPMTs). It is scheduled to be launched into space in 2016 onboard of the Chinese space laboratory TG2. We present a dedicated methodology for POLAR calibration and some calibration results based on the combined use of the laboratory radioactive sources and polarized X-ray beams from the European Synchrotron Radiation Facility. They include calibration of the energy response, computation of the energy conversion factor vs. high voltage as well as determination of the threshold values, crosstalk contributions...

  20. A unifying view of Gamma Ray Burst Afterglows

    CERN Document Server

    Ghisellini, G; Ghirlanda, G; Celotti, A

    2008-01-01

    We selected a sample of 33 Gamma Ray Bursts (GRBs) detected by Swift, with known redshift and optical extinction at the host frame. For these, we constructed the de-absorbed and K-corrected X-ray and optical rest frame light curves. These are modelled as the sum of two components: emission from the forward shock due to the interaction of a fireball with the circum-burst medium and an additional component, treated in a completely phenomenological way. The latter can be identified, among other possibilities, as "late prompt" emission produced by a long lived central engine with mechanisms similar to those responsible for the production of the "standard" early prompt radiation. Apart from flares or re-brightenings, that we do not model, we find a good agreement with the data, despite of their complexity and diversity. Although based in part on a phenomenological model with a relatively large number of free parameters, we believe that our findings are a first step towards the construction of a more physical scena...

  1. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk

    2017-02-01

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

  2. The CHIME Fast Radio Burst Project

    Science.gov (United States)

    Kaspi, Victoria M.; CHIME/FRB Collaboration

    2017-01-01

    Fast Radio Bursts are a recently discovered phenomenon consisting of short (few ms) bursts of radio waves that have dispersion measures that strongly suggest an extragalactic and possibly cosmological, but yetunknown, origin. The Canadian Hydrogen Intensity Mapping Experiment was designed to study Baryon Acoustic Oscillations through mapping of redshifted hydrogen, in order to constrain the nature of Dark Energy. CHIME, currently under construction in Penticton, BC in Canada, consists of 4 cylindrical paraboloid reflectors having total collecting area 80 m x 100 m, and will be sensitive in the 400-800 MHz band. With 2048 independent feeds hung along the cylinder axes, CHIME is a transit telescope with no moving parts, but is sensitive to the full ~200 sq. degrees overhead in 1024 formed beams, thanks to the largest correlator ever built. Given CHIME's enormous sensitivity, bandwidth and unprecedented field of view for the radio regime, CHIME will be a superb instrument for studying Fast Radio Bursts, with expected detected event rates of several to several dozen per day, hence promising major progress on the origin and nature of FRBs.

  3. Runtime Verification in Context : Can Optimizing Error Detection Improve Fault Diagnosis

    Science.gov (United States)

    Dwyer, Matthew B.; Purandare, Rahul; Person, Suzette

    2010-01-01

    Runtime verification has primarily been developed and evaluated as a means of enriching the software testing process. While many researchers have pointed to its potential applicability in online approaches to software fault tolerance, there has been a dearth of work exploring the details of how that might be accomplished. In this paper, we describe how a component-oriented approach to software health management exposes the connections between program execution, error detection, fault diagnosis, and recovery. We identify both research challenges and opportunities in exploiting those connections. Specifically, we describe how recent approaches to reducing the overhead of runtime monitoring aimed at error detection might be adapted to reduce the overhead and improve the effectiveness of fault diagnosis.

  4. What structural length scales can be detected by the spectral variance of a microscope image?

    OpenAIRE

    Cherkezyan, Lusik; Subramanian, Hariharan; Backman, Vadim

    2014-01-01

    A spectroscopic microscope, configured to detect interference spectra of backscattered light in the far zone, quantifies the statistics of refractive-index (RI) distribution via the spectral variance (Σ̃2) of the acquired bright-field image. Its sensitivity to subtle structural changes within weakly scattering, label-free media at subdiffraction scales shows great promise in fields from material science to medical diagnostics. We further investigate the length-scale sensitivity of Σ̃ and reve...

  5. Can a future mission detect a habitable ecosystem on Europa, or Ganymede?

    Science.gov (United States)

    Chela Flores, Julian

    2010-05-01

    The considerable evidence for the presence of a liquid ocean over a silicate core makes Europa a candidate for the emergence of a second evolutionary pathway of autochthonous life. The most urgent question in astrobiology is the origin of habitable ecosystems—a question in geochemistry—rather than the alternative search for the origin of life itself—a question in chemical evolution (Chela-Flores, 2010). Since certain bodies may share a similar geophysical past with the Earth, a question suggests itself: Can available instrumentation be the ‘pioneer' in the discovery of habitable ecosystems in geophysical environments similar to the early Earth, where oceans were in contact with a silicate core? A central aspect of this dilemma is the element sulphur (S). A reliable window on the nature of the early terrestrial habitable ecosystems is the Pilbara Craton (Australia), a rich fossiliferous archive of the early steps of evolution, having preserved details of ancient hydrothermal vents. It contains a 3.47 Ga barite deposit with microfossils of a complex set of sulphate-reducing bacteria (Shen and Buick, 2004). The large spread in the delta 34S values provides the earliest reliable biomarker from the early Earth. Europa may represent the only other case in the Solar System in which liquid water has been in contact with a silicate core over geologic time in perfect analogy with the early Earth (Bland et al., 2009). The following hypothesis is forced upon us: The presence of hydrothermal activity at the interface of the silicate core and the Europan ocean can provide a variety of biogenic chemicals that play a role in sustaining microbial life at the ocean floor. This is the source of microbial life elsewhere in the ocean and of biomarkers on its icy surface. This hypothesis is subject to a feasible experimental test: Europa's non-ice surficial elements were found to be widespread, patchy and, most likely, endogenous. We argue that penetrators should be inserted in

  6. Model Atmospheres for X-ray Bursting Neutron Stars

    CERN Document Server

    Medin, Zach; Calder, Alan C; Fontes, Christopher J; Fryer, Chris L; Hungerford, Aimee L

    2016-01-01

    The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of these parameters are difficult, however, due to the highly non-ideal nature of the atmospheres where X-ray bursts occur. Observations from X-ray telescopes such as RXTE and NuStar can potentially place strong constraints on nuclear matter once uncertainties in atmosphere models have been reduced. Here we discuss current progress on modeling atmospheres of X-ray bursting neutron stars and some of the challenges still to be overcome.

  7. Gamma-ray burst progenitors

    CERN Document Server

    Levan, Andrew; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-01-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; i) direct observations of GRBs and their host galaxies, ii) parameters derived from modeling, both via population synthesis and direct numerical simulation and iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous an...

  8. Gamma-Ray Burst Progenitors

    Science.gov (United States)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

  9. 30 CFR 57.3461 - Rock bursts.

    Science.gov (United States)

    2010-07-01

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

  10. A Strange Supernova with a Gamma-Ray Burst

    Science.gov (United States)

    1998-10-01

    Important Observations with La Silla Telescopes Several articles appear today in the scientific journal Nature about the strange supernova SN 1998bw that exploded earlier this year in the spiral galaxy ESO184-G82 . These studies indicate that this event was linked to a Gamma-Ray Burst and may thus provide new insights into this elusive phenomenon. Important observations of SN 1998bw have been made with several astronomical telescopes at the ESO La Silla Observatory by some of the co-authors of the Nature articles [1]. The measurements at ESO will continue during the next years. The early observations On April 25, the BeppoSAX satellite detected a Gamma-Ray Burst from the direction of the constellation Telescopium, deep in the southern sky. Although there is now general consensus that they originate in very distant galaxies, the underlying physical causes of these events that release great amounts of energy within seconds are still puzzling astronomers. Immediately after reports about the April 25 Burst had been received, astronomers at La Silla took some images of the sky region where the gamma-rays were observed as a "Target of Opportunity" (ToO) programme. The aim was to check if the visual light of one of the objects in the field had perhaps brightened when compared to exposures made earlier. This would then provide a strong indication of the location of the Gamma-Ray Burst. The digital exposures were transferred to the Italian/Dutch group around BeppoSax that had requested these ToO observations. Astronomers of this group quickly noticed a new, comparatively bright star, right on the arm of a small spiral galaxy. This galaxy was first catalogued in the 1970's during the ESO/Uppsala Survey of the Southern Sky and received the designation ESO184-G82 . It is located at a distance of about 140 million light-years. SN 1998bw ESO PR Photo 39a/98 ESO PR Photo 39a/98 [Preview - JPEG: 800 x 963 pix - 592k] [High-Res - JPEG: 3000 x 3612 pix - 4.1Mb] ESO PR Photo 39b/98

  11. Solar cosmic ray bursts and solar neutrino fluxes

    Science.gov (United States)

    Basilevakaya, G. A.; Nikolsky, S. I.; Stozhkov, Y. I.; Charakhchyan, T. N.

    1985-01-01

    The neutrino flux detected in the C1-Ar experiment seems to respond to the powerful solar cosmic ray bursts. The ground-based detectors, the balloons and the satellites detect about 50% of the bursts of soalr cosmic ray generated on the Sun's visible side. As a rule, such bursts originate from the Western side of the visible solar disk. Since the solar cosmic ray bursts are in opposite phase withthe 11-year galactic cosmic ray cycle which also seems to be reflected by neutrino experiment. The neutrino generation in the bursts will flatten the possible 11-year behavior of the AR-37 production rate, Q, in the Cl-Ar experiment. The detection of solar-flare-generated gamma-quanta with energies above tens of Mev is indicative of the generation of high-energy particles which in turn may produce neutrinos. Thus, the increased Q during the runs, when the flare-generated high energy gamma-quanta have been registered, may be regarded as additional evidence for neutrino geneation in the solar flare processes.

  12. Understanding the Continuum Spectra of Short Soft Gamma Repeater Bursts

    Science.gov (United States)

    Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; Finger, Mark H.; Lenter, Geoffrey; Patel, Sandeep K.; Swank, Jean

    2006-01-01

    The spectra of short soft gamma repeater (SGR) bursts at photon energies above -15 keV are often well described by an optically thin thermal bremsstrahlung model (i.e., F(E) - E^-1 * exp(-E/kT) ) with kT=20-40 keV. However, the spectral shape burst continuum at lower photon energies (down to -2 keV) is not well established. It is important to better understand the SGR burst spectral properties at lower energies since inadequate description of the burst spectral continuum could lead to incorrect conclusions, such as existence of spectral lines. Here, we present detailed spectral investigations (in 2-200 keV) of 163 bursts from SGR 1806-20, all detected with Rossi X-ray Timing Explorer during the 2004 active episode that included the giant flare on 27 December 2004. We find that the great majority of burst spectra are well represented by the combination of a blackbody plus a OTTB models.

  13. Prompt Optical Emission from Gamma-ray Bursts

    CERN Document Server

    Kehoe, R; Balsano, R; Barthelmy, S D; Bloch, J; Butterworth, P S; Casperson, D E; Cline, T; Fletcher, S; Frontera, F; Gisler, G; Heise, J; Hills, J; Hurley, K; Lee, B; Marshall, S; McKay, T; Pawl, A; Piro, L; Priedhorsky, B; Szymanski, J J; Wren, J; Kehoe, Robert; Akerlof, Carl; Balsano, Richard; Barthelmy, Scott; Bloch, Jeff; Butterworth, Paul; Casperson, Don; Cline, Tom; Fletcher, Sandra; Frontera, Fillippo; Gisler, Galen; Heise, John; Hills, Jack; Hurley, Kevin; Lee, Brian; Marshall, Stuart; Kay, Tim Mc; Pawl, Andrew; Piro, Luigi; Priedhorsky, Bill; Szymanski, John; Wren, Jim

    2001-01-01

    The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure contemporaneous and early afterglow optical emission from gamma-ray bursts (GRBs). The ROTSE-I telescope array has been fully automated and responding to burst alerts from the GRB Coordinates Network since March 1998, taking prompt optical data for 30 bursts in its first year. We will briefly review observations of GRB990123 which revealed the first detection of an optical burst occurring during the gamma-ray emission, reaching 9th magnitude at its peak. In addition, we present here preliminary optical results for seven other gamma-ray bursts. No other optical counterparts were seen in this analysis, and the best limiting sensitivities are m(V) > 13.0 at 14.7 seconds after the gamma-ray rise, and m(V) > 16.4 at 62 minutes. These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. This analysis suggests that there is not a strong correlation between optical flux and gamma-ray em...

  14. Identification of Bursting Water Maser Features in Orion KL

    CERN Document Server

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

    2011-01-01

    In February 2011, a burst event of the H$_{2}$O maser in Orion KL (Kleinmann-Low object) has started after 13-year silence. This is the third time to detect such phenomena in Orion KL, followed by those in 1979-1985 and 1998. We have carried out astrometric observations of the bursting H$_{2}$O maser features in Orion KL with VERA (VLBI Exploration of Radio Astrometry), a Japanese VLBI network dedicated for astrometry. The total flux of the bursting feature at the LSR velocity of 7.58 km s$^{-1}$ reaches 4.4$\\times10^{4}$ Jy in March 2011. The intensity of the bursting feature is three orders of magnitudes 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 May 2011, 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 burs...

  15. Determination of ejection velocity of rock fragments during rock burst in consideration of damage

    Institute of Scientific and Technical Information of China (English)

    ZUO Yu-jun; LI Xi-bing; ZHOU Zi-long

    2005-01-01

    The ejection velocity of rock fragments during rock burst, one of the important indexes representing the rock burst strength, is used most conveniently in the supporting design of tunnel with rock burst tendency and is often determined by means of observation devices. In order to calculate the average ejection velocity of rock fragments theoretically, the energy of rock burst was divided into damage consuming energy and kinetic energy gained by unit volume of rock firstly, and then the rock burst kinetic proportional coefficient η was brought up which could be determined according to the rock-burst damage energy index WD , at last the expression of the average ejection velocity of rock fragments during rock burst was obtained and one deep level underground tunnel was researched using the mentioned method. The results show that the calculation method is valid with or without considering the tectonic stress of tunnels, and that the method can be a reference for supporting design of deep mining.

  16. Can transthoracic Doppler echocardiography be used to detect coronary slow flow phenomenon?

    Institute of Scientific and Technical Information of China (English)

    NIE Shao-ping; LUO Tai-yang; DONG Jian-zeng; LIU Xiao-hui; MA Chang-sheng; GENG Li-li; WANG Xiao; ZHANG Xiao-shan; YANG Ya; LIU Bai-qiu; LI Jun; QIAO Yan; LIU Xin-min

    2010-01-01

    Background Coronary slow flow phenomenon (CSFP) is an important, angiographic clinical entity but is lacking non-invasive detecting techniques. This study aimed to elucidate the value of transthoracic Doppler echocardiography (TTDE) in the diagnosis and monitoring of coronary slow flow in left anterior descending (LAD) coronary artery.Methods We consecutively enrolled 27 patients with CSFP in LAD detected by coronary arteriography from August 2009 to April 2010. Thirty-eight patients with angiographically normal coronary flow served as control. Corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) was used to document coronary flow velocities. All subjects underwent TTDE within 24 hours after coronary angiography. LAD flow was detected and the coronary diastolic peak velocities (DPV) and diastolic mean velocities (DMV) were calculated.Results Sixty of 65 (92.3%) subjects successfully underwent TTDE. Baseline clinical characteristics were similar between the two groups. Coronary DPV and DMV of LAD were significantly lower in the CSFP group than in the control group ((0.228±0.029) m/s vs. (0.302±0.065) m/s, P=0.000; (0.176±0.028) m/s vs. (0.226±0.052) m/s, P=0.000,respectively). There was a high inverse correlation between CTFC and coronary DPV and DMV (r=-0.727, P=0.000;r=-0.671, P=0.000, respectively). Receiver operating characteristic (ROC) curve showed that the area under the curve (AUC) was less than one half for coronary DPV (AUC=0.104) and DMV (AUC=0.204), respectively.Conclusions In patients with CSFP, there is a high inverse correlation between CTFC and coronary diastolic flow velocities in the LAD coronary artery, as measured by TTDE. The value of TTDE in the monitoring and evaluation of coronary flow in patients with CSFP deserves further investigation.

  17. Efficacy of ultrasound elastography in detecting active myositis in children: can it replace MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Berko, Netanel S.; Levin, Terry L. [Montefiore Medical Center, Department of Radiology, Bronx, NY (United States); Hay, Arielle [Montefiore Medical Center, Department of Pediatrics, Division of Pediatric Rheumatology, Bronx, NY (United States); Miami Children' s Hospital, Department of Pediatrics, Miami, FL (United States); Sterba, Yonit; Wahezi, Dawn [Montefiore Medical Center, Department of Pediatrics, Division of Pediatric Rheumatology, Bronx, NY (United States)

    2015-09-15

    Juvenile idiopathic inflammatory myopathy is a rare yet potentially debilitating condition. MRI is used both for diagnosis and to assess response to treatment. No study has evaluated the performance of US elastography in the diagnosis of this condition in children. To assess the performance of compression-strain US elastography in detecting active myositis in children with clinically confirmed juvenile idiopathic inflammatory myopathy and to compare its efficacy to MRI. Children with juvenile idiopathic inflammatory myopathy underwent non-contrast MR imaging as well as compression-strain US elastography of the quadriceps muscles. Imaging findings from both modalities were compared to each other as well as to the clinical determination of active disease based on physical examination and laboratory data. Active myositis on MR was defined as increased muscle signal on T2-weighted images. Elastography images were defined as normal or abnormal based on a previously published numerical scale of muscle elastography in normal children. Muscle echogenicity was graded as normal or abnormal based on gray-scale sonographic images. Twenty-one studies were conducted in 18 pediatric patients (15 female, 3 male; age range 3-19 years). Active myositis was present on MRI in ten cases. There was a significant association between abnormal MRI and clinically active disease (P = 0.012). US elastography was abnormal in 4 of 10 cases with abnormal MRI and in 4 of 11 cases with normal MRI. There was no association between abnormal elastography and either MRI (P > 0.999) or clinically active disease (P > 0.999). Muscle echogenicity was normal in 11 patients; all 11 had normal elastography. Of the ten patients with increased muscle echogenicity, eight had abnormal elastography. There was a significant association between muscle echogenicity and US elastography (P < 0.001). The positive and negative predictive values for elastography in the determination of active myositis were 75% and 31

  18. Chromium(VI) release from leather and metals can be detected with a diphenylcarbazide spot test

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2015-01-01

    Along with chromium, nickel and cobalt are the clinically most important metal allergens. However, unlike for nickel and cobalt, there is no validated colorimetric spot test that detects chromium. Such a test could help both clinicians and their patients with chromium dermatitis to identify culprit...... at 0.5 ppm without interference from other pure metals, alloys, or leather. A market survey using the test showed no chromium(VI) release from work tools (0/100). However, chromium(VI) release from metal screws (7/60), one earring (1/50), leather shoes (4/100) and leather gloves (6/11) was observed. We...

  19. First LIGO search for gravitational wave bursts from cosmic (super)strings

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Adhikari, R.; Ajith, P.; Allen, B.; Allen, G.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arain, M. A.; Araya, M.; Armandula, H.; Armor, P.; Aso, Y.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Baker, P.; Ballmer, S.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Behnke, B.; Benacquista, M.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bodiya, T. P.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Bridges, D. O.; Brinkmann, M.; Brooks, A. F.; Brown, D. A.; Brummit, A.; Brunet, G.; Bullington, A.; Buonanno, A.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Cannizzo, J.; Cannon, K. C.; Cao, J.; Cardenas, L.; Caride, S.; Castaldi, G.; Caudill, S.; Cavaglià, M.; Cepeda, C.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Christensen, N.; Chung, C. T. Y.; Clark, D.; Clark, J.; Clayton, J. H.; Cokelaer, T.; Colacino, C. N.; Conte, R.; Cook, D.; Corbitt, T. R. C.; Cornish, N.; Coward, D.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Culter, R. M.; Cumming, A.; Cunningham, L.; Danilishin, S. L.; Danzmann, K.; Daudert, B.; Davies, G.; Daw, E. J.; Debra, D.; Degallaix, J.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doomes, E. E.; Drever, R. W. P.; Dueck, J.; Duke, I.; Dumas, J.-C.; Dwyer, J. G.; Echols, C.; Edgar, M.; Effler, A.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Faltas, Y.; Fan, Y.; Fazi, D.; Fehrmann, H.; Finn, L. S.; Flasch, K.; Foley, S.; Forrest, C.; Fotopoulos, N.; Franzen, A.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Garofoli, J. A.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grimaldi, F.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G. D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Haughian, K.; Hayama, K.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hodge, K. A.; Holt, K.; Hosken, D. J.; Hough, J.; Hoyland, D.; Hughey, B.; Huttner, S. H.; Ingram, D. R.; Isogai, T.; Ito, M.; Ivanov, A.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khan, R.; Khazanov, E.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Kozak, D.; Krishnan, B.; Kumar, R.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lei, H.; Lei, M.; Leindecker, N.; Leonor, I.; Li, C.; Lin, H.; Lindquist, P. E.; Littenberg, T. B.; Lockerbie, N. A.; Lodhia, D.; Longo, M.; Lormand, M.; Lu, P.; Lubiński, M.; Lucianetti, A.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Mandel, I.; Mandic, V.; Márka, S.; Márka, Z.; Markosyan, A.; Markowitz, J.; Maros, E.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McIntyre, G.; McKechan, D. J. A.; McKenzie, K.; Mehmet, M.; Melatos, A.; Melissinos, A. C.; Menéndez, D. F.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miller, J.; Minelli, J.; Mino, Y.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Mohanty, S. D.; Mohapatra, S. R. P.; Moreno, G.; Morioka, T.; Mors, K.; Mossavi, K.; Mowlowry, C.; Mueller, G.; Müller-Ebhardt, H.; Muhammad, D.; Mukherjee, S.; Mukhopadhyay, H.; Mullavey, A.; Munch, J.; Murray, P. G.; Myers, E.; Myers, J.; Nash, T.; Nelson, J.; Newton, G.; Nishizawa, A.; Numata, K.; O'Dell, J.; O'Reilly, B.; O'Shaughnessy, R.; Ochsner, E.; Ogin, G. H.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pan, Y.; Pankow, C.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Perreca, A.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Postiglione, F.; Principe, M.; Prix, R.; Prokhorov, L.; Punken, O.; Quetschke, V.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raics, Z.; Rainer, N.; Rakhmanov, M.; Raymond, V.; Reed, C. M.; Reed, T.; Rehbein, H.; Reid, S.

    2009-09-01

    We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models. Many grand unified theory-scale models (with string tension Gμ/c2≈10-6) can be ruled out at 90% confidence for reconnection probabilities p≤10-3 if loop sizes are set by gravitational back reaction.

  20. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    Science.gov (United States)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  1. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Surveys

    CERN Document Server

    Topinka, Martin

    2015-01-01

    Thanks to the advances in robotic telescopes, the time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. A special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques is used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the $g'-r'$, $r'-i'$ and $i'-z'$ colour indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of $\\gtrsim 90\\%$.

  2. Real-Time Supernova Neutrino Burst Monitor at Super-Kamiokande

    CERN Document Server

    Abe, K; Hayato, Y; Ikeda, M; Iyogi, K; Kameda, J; Kishimoto, Y; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Tanaka, H; Tomura, T; Ueno, K; Wendell, R A; Yokozawa, T; Irvine, T; Kajita, T; Kametani, I; Kaneyuki, K; Lee, K P; McLachlan, T; Nishimura, Y; Richard, E; Okumura, K; Labarga, L; Fernandez, P; Berkman, S; Tanaka, H A; Tobayama, S; Gustafson, J; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Goldhaber, M; Carminati, G; Kropp, W R; Mine, S; Weatherly, P; Renshaw, A; Smy, M B; Sobel, H W; Takhistov, V; Ganezer, K S; Hartfiel, B L; Hill, J; Keig, W E; Hong, N; Kim, J Y; Lim, I T; Akiri, T; Himmel, A; Scholberg, K; Walter, C W; Wongjirad, T; Ishizuka, T; Tasaka, S; Jang, J S; Learned, J G; Matsuno, S; Smith, S N; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Suzuki, A T; Takeuchi, Y; Bronner, C; Hirota, S; Huang, K; Ieki, K; Kikawa, T; Minamino, A; Murakami, A; Nakaya, T; Suzuki, K; Takahashi, S; Tateishi, K; Fukuda, Y; Choi, K; Itow, Y; Mitsuka, G; Mijakowski, P; Hignight, J; Imber, J; Jung, C K; Yanagisawa, C; Wilking, M J; Ishino, H; Kibayashi, A; Koshio, Y; Mori, T; Sakuda, M; Yamaguchi, R; Yano, T; Kuno, Y; Tacik, R; Kim, S B; Okazawa, H; Choi, Y; Nishijima, K; Koshiba, M; Suda, Y; Totsuka, Y; Yokoyama, M; Martens, K; Marti, Ll; Vagins, M R; Martin, J F; de Perio, P; Konaka, A; Chen, S; Zhang, Y; Connolly, K; Wilkes, R J

    2016-01-01

    We present a real-time supernova neutrino burst monitor at Super-Kamiokande (SK). Detecting supernova explosions by neutrinos in real time is crucial for giving a clear picture of the explosion mechanism. Since the neutrinos are expected to come earlier than light, a fast broadcasting of the detection may give astronomers a chance to make electromagnetic radiation observations of the explosions right at the onset. The role of the monitor includes a fast announcement of the neutrino burst detection to the world and a determination of the supernova direction. We present the online neutrino burst detection system and studies of the direction determination accuracy based on simulations at SK.

  3. Can we detect a nonlinear response to temperature in European plant phenology?

    Science.gov (United States)

    Jochner, Susanne; Sparks, Tim H.; Laube, Julia; Menzel, Annette

    2016-10-01

    Over a large temperature range, the statistical association between spring phenology and temperature is often regarded and treated as a linear function. There are suggestions that a sigmoidal relationship with definite upper and lower limits to leaf unfolding and flowering onset dates might be more realistic. We utilised European plant phenological records provided by the European phenology database PEP725 and gridded monthly mean temperature data for 1951-2012 calculated from the ENSEMBLES data set E-OBS (version 7.0). We analysed 568,456 observations of ten spring flowering or leafing phenophases derived from 3657 stations in 22 European countries in order to detect possible nonlinear responses to temperature. Linear response rates averaged for all stations ranged between -7.7 (flowering of hazel) and -2.7 days °C-1 (leaf unfolding of beech and oak). A lower sensitivity at the cooler end of the temperature range was detected for most phenophases. However, a similar lower sensitivity at the warmer end was not that evident. For only ˜14 % of the station time series (where a comparison between linear and nonlinear model was possible), nonlinear models described the relationship significantly better than linear models. Although in most cases simple linear models might be still sufficient to predict future changes, this linear relationship between phenology and temperature might not be appropriate when incorporating phenological data of very cold (and possibly very warm) environments. For these cases, extrapolations on the basis of linear models would introduce uncertainty in expected ecosystem changes.

  4. Junctional kyphosis: how can we detect and monitor it during growth?

    Directory of Open Access Journals (Sweden)

    Alessandra Negrini

    2016-10-01

    Full Text Available Abstract Background Despite its importance in affecting adult pain, and disability, there is a lack of universal criteria for the diagnosis and evaluation of thoraco-lumbar Junctional Kyphosis (JK and a gold standard measurement and diagnostic system does not exist. This study aims to verify the sensibility and specificity of clinical, and Formetric surface topography (FST data in identifying Junctional Kyphosis in respect to the radiographical standard references. Methods Design: This is a cross sectional study from a prospective database started in March 2003. Participants: 38 subjects. Inclusion criteria: Patients selected by age according to Risser score 1, at first visit with lateral x-rays and FST. Diagnostic test used to detect JK: FST criteria: level of thoraco-lumbar inflexion point in percentage compared to the total height of the spine. X-ray criteria: lower limit of thoracic kyphosis below T12. Statistics: sensitivity, specificity, positive (PPV and negative predictive values (NPV, ROC curve. Results FST showed a good reliability in detecting JK: with a threshold of 75 %, PPV was 100 %, NPV was 86 % and the Area Under the Curve was 83 %. Conclusion The need for a useful criteria able to characterize JK to allow diagnosis and monitoring of the deformity is still lacking, and further studies will deepen this issue.

  5. Variation of Spectral and Timing Properties in the Extended Burst Tails from the Magnetar 4U 0142+61

    CERN Document Server

    Chakraborty, Manoneeta; Muş, Sinem Şaşmaz; Kaneko, Yuki

    2016-01-01

    Extended emission episodes with intensity above the pre-burst level are observed following magnetar bursts from a number of soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). Such extended tail emission were observed subsequent to two events detected from AXP 4U 0142+61. We investigated in detail the evolution of spectral and temporal properties during these two tail segments using RXTE/PCA observations, and report distinct variations both in the spectral and temporal behavior throughout the tails. In particular, sudden enhancement of pulsation amplitude in conjunction with bursts, and smooth decline of X-ray emission (cooling) during the tail were observed in both cases. We suggest that an inefficiently radiating trapped fireball formed during the burst, which can heat up the stellar surface, is able to explain the tail properties and its energetics. We also present the episodic detection of absorption and emission features during tails. One possible mechanism that has been proposed to give rise...

  6. Origin of wide-band IP type II bursts

    Science.gov (United States)

    Pohjolainen, S.; Allawi, H.; Valtonen, E.

    2013-10-01

    . Conclusions: We conclude that in most cases (in 18 out of 25 events) the wide-band IP type II bursts can be plasma emission, formed at or just above the CME leading edge. The results for the remaining seven events might suggest the possibility of a synchrotron source. These events, however, occurred during periods of high solar activity, and coronal conditions affecting the results of the burst height calculations cannot be ruled out. The observed wide and diffuse emission bands may also indicate specific CME leading edge structures and special shock conditions. Figures 2-26 and Table 4 are available in electronic form at http://www.aanda.org

  7. Do Gamma-Ray Burst Sources Repeat?

    OpenAIRE

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb 1993; Wang and Lingenfelter 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al. 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and...

  8. Light speed variation from gamma-ray bursts

    CERN Document Server

    Xu, Haowei

    2016-01-01

    The effect of quantum gravity can bring a tiny light speed variation which is detectable through energetic photons propagating from gamma ray bursts (GRBs) to an observer such as the space observatory. Through an analysis of the energetic photon data of the GRBs observed by the Fermi Gamma-ray Space Telescope (FGST), we reveal a surprising regularity of the observed time lags between photons of different energies with respect to the Lorentz violation factor due to the light speed energy dependence. Such regularity suggests a linear form correction of the light speed $v(E)=c(1-E/E_{\\rm LV})$, where $E$ is the photon energy and $E_{\\rm LV}=(3.60 \\pm 0.26) \\times 10^{17}~ \\rm GeV$ is the Lorentz violation scale measured by the energetic photon data of GRBs. The results support an energy dependence of the light speed in cosmological space.

  9. Risk evaluation of rock burst through theory of static and dynamic stresses superposition

    Institute of Scientific and Technical Information of China (English)

    李振雷; 蔡武; 窦林名; 何江; 王桂峰; 丁言露

    2015-01-01

    Rock burst is one of the most catastrophic dynamic hazards in coal mining. A static and dynamic stresses superposition-based (SDSS-based) risk evaluation method of rock burst was proposed to pre-evaluate rock burst risk. Theoretical basis of this method is the stress criterion incurring rock burst and rock burst risk is evaluated according to the closeness degree of the total stress (due to the superposition of static stress in the coal and dynamic stress induced by tremors) with the critical stress. In addition, risk evaluation criterion of rock burst was established by defining the “Satisfaction Degree” of static stress. Furthermore, the method was used to pre-evaluate rock burst risk degree and prejudge endangered area of an insular longwall face in Nanshan Coal Mine in China. Results show that rock burst risk is moderate at advance extent of 97 m, strong at advance extent of 97−131 m, and extremely strong (i.e. inevitable to occur) when advance extent exceeds 131 m (mining is prohibited in this case). The section of two gateways whose floor abuts 15−3 coal seam is a susceptible area prone to rock burst. Evaluation results were further compared with rock bursts and tremors detected by microseismic monitoring. Comparison results indicate that evaluation results are consistent with microseismic monitoring, which proves the method’s feasibility.

  10. Detection of Geoneutrinos: Can We Make the Gnus Work for Us?

    CERN Document Server

    Learned, John G

    2008-01-01

    The detection of electron anti-neutrinos from natural radioactivity in the earth has been a goal of neutrino researchers for about half a century. It was accomplished by the KamLAND Collaboration in 2005, and opens the way towards studies of the Earth's radioactive content, with very important implications for geology. New detectors are operating (KamLAND and Borexino), building (SNO+) and being proposed (Hanohano, LENA, Earth and others) that will go beyond the initial observation and allow interesting geophysical and geochemical research, in a means not otherwise possible. Herein we describe the approaches being taken (large liquid scintillation instruments), the experimental and technical challenges (optical detectors, directionality), and prospects for growth of this field. There is related spinoff in particle physics (neutrino oscillations and hierarchy determination), astrophysics (solar neutrinos, supernovae, exotica), and in the practical matter of remote monitoring of nuclear reactors.

  11. Earlier detection can help avoid many serious complications of peripartum cardiomyopathy.

    Science.gov (United States)

    Fett, James D

    2013-11-01

    Peripartum cardiomyopathy (PPCM) has a remarkable potential for recovery. It may be within our capability to help almost all women with PPCM not only to survive, but also to completely recover heart function. Time-of-diagnosis left ventricular ejection fraction (LVEF) ≥0.35 is associated with better survival rates and higher full recovery rates. Increased mortality, chronic cardiomyopathy, thromboembolic complications and serious ventricular tachyarrhythmias are associated with diagnostic LVEF <0.30. Delays in diagnosis may result in lower LVEF at diagnosis and subsequent lower recovery rates. Greater awareness of the possibility of heart failure developing in previously healthy young women, with no history of heart disease, will contribute to earlier diagnosis, with potentially better preserved heart function. Women of African descent may be at higher risk for poorer outcomes. Recent investigations suggest newer biomarkers may help with earlier detection of PPCM.

  12. Dual-energy CT can detect malignant lymph nodes in rectal cancer

    DEFF Research Database (Denmark)

    Al-Najami, I.; Lahaye, M. J.; Beets-Tan, Regina G H

    2017-01-01

    node assessment, and compared it to Magnetic Resonance Imaging (MRI). The objective of this prospective observational feasibility study was to determine the clinical value of the DECT for the detection of metastases in the pelvic lymph nodes of rectal cancer patients and compare the findings to MRI......Background There is a need for an accurate and operator independent method to assess the lymph node status to provide the most optimal personalized treatment for rectal cancer patients. This study evaluates whether Dual Energy Computed Tomography (DECT) could contribute to the preoperative lymph...... and histopathology. Materials and methods The patients were referred to total mesorectal excision (TME) without any neoadjuvant oncological treatment. After surgery the rectum specimen was scanned, and lymph nodes were matched to the pathology report. Fifty-four histology proven rectal cancer patients received...

  13. Can traditional epidemiology detect cancer risks caused by occupational exposure to pesticides?

    Energy Technology Data Exchange (ETDEWEB)

    Georgellis, A. [Environmental Illness Research Center, Huddinge (Sweden); Kolmodin-Hedman, B. [Karolinska Inst., Stockholm (Sweden). Dept. of Public Health Sciences; Kouretas, D. [Thessaly Univ. , Pedion Areos, Volos (Greece). School of Agriculture

    1999-06-01

    In order to investigate the possible relationship between cancer and occupational exposure to pesticides, the authors reviewed the latest literature of the epidemiological studies in this area coming to the conclusion that, while several studies indicate a link between certain pesticides and certain tumors, this information is still insufficient, and further research on the health consequence of exposure to pesticides is needed. Moreover, provided there is a risk, it is often too limited to be detected by available epidemiological techniques. Therefore, in addition to the epidemiological studies, the development of new biology, gene technology and medical biotechnology methods may significantly enhance the specificity of the epidemiological studies. Thus, the fusion of molecular biology and epidemiology into molecular epidemiology may provide more specific methods for monitoring the occupational dependent carcinogenic risk of individuals and groups.

  14. Geographic patterns of (genetic, morphologic, linguistic) variation: how barriers can be detected by using Monmonier's algorithm.

    Science.gov (United States)

    Manni, Franz; Guérard, Etienne; Heyer, Evelyne

    2004-04-01

    When sampling locations are known, the association between genetic and geographic distances can be tested by spatial autocorrelation or regression methods. These tests give some clues to the possible shape of the genetic landscape. Nevertheless, correlation analyses fail when attempting to identify where genetic barriers exist, namely, the areas where a given variable shows an abrupt rate of change. To this end, a computational geometry approach is more suitable because it provides the locations and the directions of barriers and because it can show where geographic patterns of two or more variables are similar. In this frame we have implemented Monmonier's (1973) maximum difference algorithm in a new software package to identify genetic barriers. To provide a more realistic representation of the barriers in a genetic landscape, we implemented in the software a significance test by means of bootstrap matrices analysis. As a result, the noise associated with genetic markers can be visualized on a geographic map and the areas where genetic barriers are more robust can be identified. Moreover, this multiple matrices approach can visualize the patterns of variation associated with different markers in the same overall picture. This improved Monmonier's method is highly reliable and can be applied to nongenetic data whenever sampling locations and a distance matrix between corresponding data are available.

  15. Microarray analysis after RNA amplification can detect pronounced differences in gene expression using limma

    Directory of Open Access Journals (Sweden)

    Orengo Christine

    2006-10-01

    Full Text Available Abstract Background RNA amplification is necessary for profiling gene expression from small tissue samples. Previous studies have shown that the T7 based amplification techniques are reproducible but may distort the true abundance of targets. However, the consequences of such distortions on the ability to detect biological variation in expression have not been explored sufficiently to define the true extent of usability and limitations of such amplification techniques. Results We show that expression ratios are occasionally distorted by amplification using the Affymetrix small sample protocol version 2 due to a disproportional shift in intensity across biological samples. This occurs when a shift in one sample cannot be reflected in the other sample because the intensity would lie outside the dynamic range of the scanner. Interestingly, such distortions most commonly result in smaller ratios with the consequence of reducing the statistical significance of the ratios. This becomes more critical for less pronounced ratios where the evidence for differential expression is not strong. Indeed, statistical analysis by limma suggests that up to 87% of the genes with the largest and therefore most significant ratios (p -20 in the unamplified group have a p-value below 10e-20 in the amplified group. On the other hand, only 69% of the more moderate ratios (10e-20 -10 in the unamplified group have a p-value below 10e-10 in the amplified group. Our analysis also suggests that, overall, limma shows better overlap of genes found to be significant in the amplified and unamplified groups than the Z-scores statistics. Conclusion We conclude that microarray analysis of amplified samples performs best at detecting differences in gene expression, when these are large and when limma statistics are used.

  16. The Nature of Gamma Ray Burst Supernovae

    OpenAIRE

    Cano, Zach

    2012-01-01

    Gamma Ray Bursts (GRBs) and Supernovae (SNe) are among the brightest and most energetic physical processes in the universe. It is known that core-collapse SNe arise from the gravitational collapse and subsequent explosion of massive stars (the progen- itors of nearby core-collapse SNe have been imaged and unambiguously identified). It is also believed that the progenitors of long-duration GRBs (L-GRBs) are massive stars, mainly due to the occurrence and detection of very energetic core-collap...

  17. 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.

  18. Burst-only sources: probing type I X-ray bursters at low persistent luminosities

    Energy Technology Data Exchange (ETDEWEB)

    Cornelisse, R.; Zand, J.J.M. in ' t; Kuulkers, E.; Heise, J.; Verbunt, F.; Cocchi, M.; Bazzano, A.; Natalucci, L.; Ubertini, P

    2004-06-01

    The Wide Field Cameras onboard BeppoSAX observed 9 type I X-ray bursters without detectable persistent emission around the burst. According to the standard theory of X-ray bursts these sources should be in the lowest mass-accretion regime, opening the possibility to study this regime for the first time. We compare the sources with the burst theory, and show that the evidence of a new sub-class of low mass X-ray binaries, the burst-only source, is still meagre.

  19. Self-similar traffic analysis in optical burst assembly

    Institute of Scientific and Technical Information of China (English)

    Sui Zhicheng; Zeng Qingji; Xiao Shilin

    2005-01-01

    This paper investigates the traffic properties before and after assembly at edge node of Ethernet over optical burst switching (OBS) network for the first time. Burst and inter-arrival time distributions are simulated under time-based and length-based assembly schemes. Self-similar traffic Hurst parameter is compared through R/S and V/T plot. Finally three self-similar traffic generating methods are given. Simulation results demonstrate that, multi-source traffic increases self-similar degree, however after assembly, time-based scheme can decrease self-similar degree, and aggregated burst size is close to Gaussian distribution. Length-based method has no effects on the self-similarity of input traffic. RMD is fit for study of burst network with large self-similarity.

  20. First upper limits from LIGO on gravitational wave bursts

    Energy Technology Data Exchange (ETDEWEB)

    B. Abbott et al.

    2004-03-09

    We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h{sub rss}; typical sensitivities lie in the range h{sub rss} {approx} 10{sup -19} - 10{sup -17} strain/{radical}Hz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.

  1. First upper limits from LIGO on gravitational wave bursts

    CERN Document Server

    Abbott, B; Adhikari, R; Ageev, A N; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S V; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, D; Barker-Patton, C; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff,S J; Betzwieser, J; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Bland-Weaver, B; Bochner, B; Bogue, L; Bork, R G; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Brozek, S; Bullington, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Colacino, C N; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Davies, R; Daw, E; De Bra, D; Delker, T; DeSalvo, R; Dhurandhar, S V; Ding, H; Drever, R W P; Dupuis, R J; Ebeling, C; Edlund, J; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fallnich, C; Farnham, D; Fejer, M M; Fine, M; Finn, L S; Flanagan, E; Freise, A; Frey, R; Fritschel, P; Frolov, V; Fyffe, M; Ganezer, K S; Giaime, J A; Gillespie, A; Goda, K; González, G; Goler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ingley, R; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, W W; Johnston, W; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Kloevekorn, P; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonhardt, V; Leonor, I; Libbrecht, K; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Lück, H B; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K O; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNamara, P; Mendell, G; Meshkov, S; Messenger, C; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Mours, B; Müller, G; Mukherjee, S; Myers, J; Nagano, S; Nash, T; Naundorf, H; Nayak, R; Newton, G; Nocera, F; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Papa, M A; Parameswariah, C; Parameshwaraiah, V; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Pratt, M; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Redding, D; Regehr, M W; Regimbau, T; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schofield, R; Schrempel, M; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seel, S; Sengupta, A S; Shapiro, C A; Shawhan, P S; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Skeldon, K D; Smith, J R; Smith, M; Smith, M R; Sneddon, P; Spero, R; Stapfer, G; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Torres, C; Torrie, C; Traeger, S; Traylor, G; Tyler, W; Ugolini, D W; Vallisneri, M; Van, M; Putten; Vass, S; Vecchio, A; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Yakushin, I; Yamamoto, H; Yoshida, S; Zawischa, I; Zhang, L; Zotov, N P; Zucker, M; Zweizig, J

    2004-01-01

    We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.

  2. Type I X-ray bursts and burst oscillations in the accreting millisecond X-ray pulsar IGR J17511-3057

    CERN Document Server

    Altamirano, D; Linares, M; Markwardt, C B; Strohmayer, T; Patruno, A

    2010-01-01

    We report the discovery of burst oscillations at the spin frequency in ten thermonuclear bursts from the accreting millisecond X-ray pulsar (AMXP) IGR J17511-3057. The burst oscillation properties are, like those from the AMXPs SAX J1808.4-3658 and XTE J1814-338, anomalous compared to burst oscillations from intermittent pulsars or non-pulsing LMXBs. Like SAX J1808.4-3658 they show frequency drifts in the rising phase rather than the tail. There is also evidence for harmonic content. Where IGR J17511-3057 is unusual compared to the other pulsars is that oscillations are not detected throughout all bursts. As accretion rate drops the bursts get brighter and their rise/decay time scales become shorter, while the oscillation amplitude falls below the detection threshold: first in the burst peak and then also in the rise. None of the bursts from IGR J17511-3057 show evidence for photospheric radius expansion (which might be expected to suppress oscillation amplitude) which allow us to set an upper limit to the di...

  3. Can we detect water stressed areas in forest thanks thermal infrared remote sensing?

    Science.gov (United States)

    Nourtier, Marie; Chanzy, André; Bes, Bernard; Mariotte, Nicolas

    2010-05-01

    In Mediterranean and mountainous areas, an increase of mortality in forest is observed after important drought events. In the context of climate changes, a study of the impact of drought stress on forest is necessary. In order to detect water stress over the whole forest at different periods of the year, we propose the use of a spatialisable indicator, easily measurable: crown surface temperature. As previous works were not conclusive concerning the potentiality of this indicator in forest (Duchemin, 1998a, 1998b, Pierce et al., 1990), we set up an experimentation to study the surface temperature evolution linked to the transpiration at tree scale, during the spring and summer periods on silver fir (Abies alba) forest of Mont Ventoux (south of France). At the same time, several thermal infrared images of the mountainside were acquired corresponding to different levels of transpiration. The signal of surface temperature is studying via the evolution of the difference between measured surface temperature and calculated surface temperature for a tree at maximum transpiration rate. At tree scale, there is a difference of 4 °C of amplitude in the signal of surface temperature between maximum and zero transpiration conditions. The difficulty resides in taking into account the influence of climatic conditions, source of variability in the signal uncorrelated with transpiration evolution. Indices of surface temperature, built to include this influence of climatic conditions, permit to reduce this variability. Another source of variability lies in the percentage of branches present in the area of measurement. Indeed branches have a thermal dynamic differing from the needles one and, considering comparison between trees, the percentage of branches varies. At the mountainside scale, contrasted areas in terms of surface temperature indices are observable. By comparing different dates, corresponding to different levels of drought, it is possible to locate areas with precocious

  4. A population study of type II bursts in the Rapid Burster

    CERN Document Server

    Bagnoli, T; D'Angelo, C R; Galloway, D K

    2015-01-01

    Type II bursts are thought to arise from instabilities in the accretion flow onto a neutron star in an X-ray binary. Despite having been known for almost 40 years, no model can yet satisfactorily account for all their properties. To shed light on the nature of this phenomenon and provide a reference for future theoretical work, we study the entire sample of Rossi X-ray Timing Explorer data of type II bursts from the Rapid Burster (MXB 1730-335). We find that type II bursts are Eddington-limited in flux, that a larger amount of energy goes in the bursts than in the persistent emission, that type II bursts can be as short as 0.130 s, and that the distribution of recurrence times drops abruptly below 15-18 s. We highlight the complicated feedback between type II bursts and the NS surface thermonuclear explosions known as type I bursts, and between type II bursts and the persistent emission. We review a number of models for type II bursts. While no model can reproduce all the observed burst properties and explain...

  5. The Return of the Bursts: Thermonuclear Flashes from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Watts, A.; Altamirano, D.; Soleri, P.; Degenaar, N.; Yang, Y.; Wijnands, R.; Casella, P.; Homan, J.; Chakrabarty, D.; Rea, N.; Armas-Padilla, M.; Cavecchi, Y.; Kalamkar, M.; Kaur, R.; Patruno, A.; van der Klis, M.

    2010-01-01

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 (Cir X-1) during its 2010 May X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, 25 years ago.

  6. The Return of the Bursts : Thermonuclear Flashes from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Watts, A.; Altamirano, D.; Soleri, P.; Degenaar, N.; Yang, Y.; Wijnands, R.; Casella, P.; Homan, J.; Chakrabarty, D.; Rea, N.; Armas-Padilla, M.; Cavecchi, Y.; Kalamkar, M.; Kaur, R.; Patruno, A.; van der Klis, M.

    2010-01-01

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 (Cir X-1) during its 2010 May X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, 25 years ago.

  7. Hard burst emission from the soft gamma repeater SGR 1900+14

    NARCIS (Netherlands)

    P.M. Woods; C. Kouveliotou; J. van Paradijs; M.S. Briggs; K. Hurley; E. Göğüş; R.D. Preece; T.W. Giblin; C. Thompson; R.C. Duncan

    1999-01-01

    We present evidence for burst emission from SGR 1900+14 with a power-law high-energy spectrum extending beyond 500 keV. Unlike previous detections of high-energy photons during bursts from soft gamma repeaters (SGRs), these emissions are not associated with extraordinarily bright flares. Not only is

  8. The Fermi GBM Gamma-Ray Burst Spectral Catalog: Four Years of Data

    NARCIS (Netherlands)

    Gruber, D.; Goldstein, A.; Weller von Ahlefeld, V.; Bhat, N.P.; Bissaldi, E.; Briggs, M.S.; Byrne, D.; Cleveland, W.H.; Connaughton, V.; Diehl, R.; Fishman, G.J.; Fitzpatrick, G.; Foley, S.; Gibby, M.; Giles, M.M.; Greiner, J.; Guiriec, S.; van der Horst, A.J.; von Kienlin, A.; Kouveliotou, C.; Layden, E.; Lin, L.; Meegan, C.A.; McGlynn, S.; Paciesas, W.S.; Pelassa, V.; Preece, R.D.; Rau, A.; Wilson-Hodge, C.A.; Xiong, S.; Younes, G.; Yu, H-F.

    2014-01-01

    In this catalog we present the updated set of spectral analyses of gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor during its first four years of operation. It contains two types of spectra, time-integrated spectral fits and spectral fits at the brightest time bin, from 943 tri

  9. The afterglow, redshift and extreme energetics of the gamma-ray burst of 23 January 1999

    NARCIS (Netherlands)

    Kulkarni, [No Value; Djorgovski, SG; Odewahn, SC; Bloom, JS; Gal, RR; Koresko, CD; Harrison, FA; Lubin, LM; Armus, L; Sari, R; Illingworth, GD; Kelson, DD; Magee, DK; van Dokkum, PG; Frail, DA; Mulchaey, JS; Malkan, MA; McClean, IS; Teplitz, HI; Koerner, D; Kirkpatrick, D; Kobayashi, N; Yadigaroglu, IA; Halpern, J; Piran, T; Goodrich, RW; Chaffee, FH; Feroci, M; Costa, E

    1999-01-01

    Long-lived emission, known as afterglow, has now been detected from about a dozen gamma-ray bursts. Distance determinations place the bursts at cosmological distances, with redshifts,z, ranging from similar to 1 to 3, The energy required to produce these bright gamma-ray flashes is enormous: up to s

  10. Detecting Bias in Meta-Analyses of Distance Education Research: Big Pictures We Can Rely On

    Science.gov (United States)

    Bernard, Robert M.; Borokhovski, Eugene; Tamim, Rana M.

    2014-01-01

    This article has two interrelated purposes. The first is to explain how various forms of bias, if introduced during any stage of a meta-analysis, can provide the consumer with a misimpression of the state of a research literature. Five of the most important bias-producing aspects of a meta-analysis are presented and discussed. Second, armed with…

  11. The return of the bursts: Thermonuclear flashes from Circinus X-1

    CERN Document Server

    Linares, M; Altamirano, D; Soleri, P; Degenaar, N; Yang, Y; Wijnands, R; Casella, P; Homan, J; Chakrabarty, D; Rea, N; Armas-Padilla, M; Cavecchi, Y; Kalamkar, M; Kaur, R; Patruno, A; van der Klis, M

    2010-01-01

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 during its May 2010 X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, twenty-five years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.

  12. Can Tonne-Scale Direct Detection Experiments Discover Nuclear Dark Matter?

    CERN Document Server

    Butcher, A; Monroe, J; West, S M

    2016-01-01

    Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with a decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the $3\\,\\sigma$ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a $2\\,\\sigma$ distinction is possible by these e...

  13. Can the envisaged reductions of fossil fuel CO2 emissions be detected by atmospheric observations?

    Science.gov (United States)

    Levin, Ingeborg; Rödenbeck, Christian

    2008-03-01

    The lower troposphere is an excellent receptacle, which integrates anthropogenic greenhouse gases emissions over large areas. Therefore, atmospheric concentration observations over populated regions would provide the ultimate proof if sustained emissions changes have occurred. The most important anthropogenic greenhouse gas, carbon dioxide (CO(2)), also shows large natural concentration variations, which need to be disentangled from anthropogenic signals to assess changes in associated emissions. This is in principle possible for the fossil fuel CO(2) component (FFCO(2)) by high-precision radiocarbon ((14)C) analyses because FFCO(2) is free of radiocarbon. Long-term observations of (14)CO(2) conducted at two sites in south-western Germany do not yet reveal any significant trends in the regional fossil fuel CO(2) component. We rather observe strong inter-annual variations, which are largely imprinted by changes of atmospheric transport as supported by dedicated transport model simulations of fossil fuel CO(2). In this paper, we show that, depending on the remoteness of the site, changes of about 7-26% in fossil fuel emissions in respective catchment areas could be detected with confidence by high-precision atmospheric (14)CO(2) measurements when comparing 5-year averages if these inter-annual variations were taken into account. This perspective constitutes the urgently needed tool for validation of fossil fuel CO(2) emissions changes in the framework of the Kyoto protocol and successive climate initiatives.

  14. Natural history traits associated with detecting mortality within residential bird communities: can citizen science provide insights?

    Science.gov (United States)

    Cooper, Caren Beth; Loyd, Kerrie Anne Therese; Murante, Tessa; Savoca, Matthew; Dickinson, Janis

    2012-07-01

    Cat predation of birds in residential landscapes is ephemeral, unpredictable, and spatially dispersed, and thus requires many person-hours to observe. We sought to identify whether specific behaviors, traits, or feeding ecologies of birds contribute to their probability of cat-caused mortality around residences across temperate North America. In addressing this question, we evaluated citizen science data with respect to peer-reviewed species accounts (Birds of North America, BNA). Using information on cat predation from the BNA, we found that species that glean their prey from the ground or breed in nest boxes were three times more likely to be depredated by cats, while birds that hawk were over two times less likely to become cat prey than would be predicted by random chance. Data from citizen science sources also showed that birds using nest boxes had increased susceptibility to cat predation, as did those that use feeders and that glean from foliage. We caution that observations of predation by citizen science volunteers may be biased towards detection at feeders. Future research should focus on developing volunteer survey techniques for improving estimates of bird mortality rates and sources.

  15. Gamma-Ray Bursts: Pulses and Populations

    Science.gov (United States)

    Loredo, Thomas J.; Hakkila, J. E.; Broadbent, M.; Wasserman, I. M.; Wolpert, R. L.

    2013-04-01

    We describe ongoing work on two projects that are enabling more thorough and accurate use of archival BATSE data for elucidating the nature of GRB sources; the methods and tools we are developing will also be valuable for analyzing data from other missions. The first project addresses modeling the spectro-temporal behavior of prompt gamma ray emission from GRBs by modeling gamma ray count and event data with a population of pulses, with the population drawn from one or more families of single-pulse kernels. Our approach is built on a multilevel nonparametric probabilistic framework we have dubbed "Bayesian droplets," and offers several important advances over previous pulse decomposition approaches: (1) It works in the pulse-confusion regime, quantifying uncertainty in the number, locations, and shapes of pulses, even when there is strong overlap. (2) It can self-consistently model pulse behavior across multiple spectral bands. (3) It readily handles a variety of spatio-temporal kernel shapes. (4) It reifies the idea of a burst as a population of pulses, enabling explicit modeling and estimation of the pulse population distribution. We describe the framework and present analyses of prototypical simple and complex GRB light curves. The second project aims to enable accurate demographic modeling of GRBs using the BATSE catalog. We present new calculations of the BATSE sky exposure, encompassing the full duration of the BATSE catalog for the first time, with many improvements over the currently available exposure map. A similar calculation of the detection efficiency is in progress. We also describe public Python software enabling access and accurate modeling of BATSE GRB data. The software enables demographic studies (e.g., modeling log N - log S distributions) with accurate accounting of both selection effects and measurement errors. It also enables spectro-temporal modeling of detailed data from individual GRBs. These projects are supported by NASA through the AISR

  16. 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...

  17. 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.

  18. Automatic Cloud Bursting under FermiCloud

    Energy Technology Data Exchange (ETDEWEB)

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

    1900-01-01

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

  19. More Gamma-ray Bursts from the Fermi Gamma-ray Burst Monitor

    Science.gov (United States)

    Briggs, Michael; Fermi GBM Team Team

    2017-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) Team has developed an offline search for weak gamma-ray bursts which were not already detected in-orbit as ``triggers''. This search is ``untargeted'', searching all of the GBM data without guidance from other observations. The initial version of the search has been operational from January 2016, finding several likely short GRBs per month that are posted to a webpage. The GBM individual photon data are binned to various timescales, a background model is created and the binned data are searched for significant signals above the background that are coincident in two or more detectors. The current search has a latency of several days because several steps require manual intervention. An improved version will be fully automatic so that the latency in detecting candidates will be dominated by the few hours delay in receiving the data. The new version of the search will also include additional detection algorithms to increase the GRB detection rate and will also detect some long GRBs. We will report the candidates via the Gamma-ray Coordinates Network (GCN). These prompt GRB detections and localization should aid multi-messenger observations, in some cases refining localizations on timescales useful for followup observations.

  20. How Can We Improve the Detection of Alpha1-Antitrypsin Deficiency?

    Directory of Open Access Journals (Sweden)

    Ilaria Ferrarotti

    Full Text Available The Z deficiency in α1-antitrypsin (A1ATD is an under-recognized condition. Alpha1-antitrypsin (A1AT is the main protein in the α1-globulin fraction of serum protein electrophoresis (SPE; however, evaluation of the α1-globulin protein fraction has received very little attention. Serum Z-type A1AT manifests in polymeric forms, but their interference with quantitative immunoassays has not been reported. Here, 214 894 samples were evaluated by SPE at the G. Fracastoro Hospital of Verona, Italy. Patients with an A1AT level ≤ 0.92 g/L were recalled to complete A1ATD diagnosis. In parallel, to qualitatively and quantitatively characterize A1AT, sera samples from 10 PiZZ and 10 PiMM subjects obtained at the National Institute of Tuberculosis and Lung Diseases in Warsaw, Poland, were subjected to non-denaturing 7.5% PAGE and 7.5% SDS-PAGE followed by Western blot. Moreover, purified A1AT was heated at 60°C and analyzed by a non-denaturing PAGE and 4-15% gradient SDS-PAGE followed by Western blot as well as by isolelectrofocusing and nephelometry. A total of 966 samples manifested percentages ≤ 2.8 or a double band in the alpha1-zone. According to the nephelometry data, 23 samples were classified as severe (A1AT ≤ 0.49 g/L and 462 as intermediate (A1AT >0.49≤ 1.0 g/L A1ATD. Twenty subjects agreed to complete the diagnosis and an additional 21 subjects agreed to family screening. We detected 9 cases with severe and 26 with intermediate A1ATD. Parallel experiments revealed that polymerization of M-type A1AT, when measured by nephelometry or isolelectrofocusing, yields inaccurate results, leading to the erroneous impression that it was Z type and not M-type A1AT. We illustrate the need for confirmation of Z A1AT values by "state of the art" method. Clinicians should consider a more in-depth investigation of A1ATD in patients when they exhibit serum polymers and low α1-globulin protein levels by SPE.

  1. How Can We Improve the Detection of Alpha1-Antitrypsin Deficiency?

    Science.gov (United States)

    Trevisan, Maria Teresa; Dresel, Marc; Koczulla, Rembert; Ottaviani, Stefania; Baldo, Raffaele; Gorrini, Marina; Sala, Giorgia; Cavallon, Luana; Welte, Tobias; Chorostowska-Wynimko, Joanna; Luisetti, Maurizio; Janciauskiene, Sabina

    2015-01-01

    The Z deficiency in α1-antitrypsin (A1ATD) is an under-recognized condition. Alpha1-antitrypsin (A1AT) is the main protein in the α1-globulin fraction of serum protein electrophoresis (SPE); however, evaluation of the α1-globulin protein fraction has received very little attention. Serum Z-type A1AT manifests in polymeric forms, but their interference with quantitative immunoassays has not been reported. Here, 214 894 samples were evaluated by SPE at the G. Fracastoro Hospital of Verona, Italy. Patients with an A1AT level ≤ 0.92 g/L were recalled to complete A1ATD diagnosis. In parallel, to qualitatively and quantitatively characterize A1AT, sera samples from 10 PiZZ and 10 PiMM subjects obtained at the National Institute of Tuberculosis and Lung Diseases in Warsaw, Poland, were subjected to non-denaturing 7.5% PAGE and 7.5% SDS-PAGE followed by Western blot. Moreover, purified A1AT was heated at 60°C and analyzed by a non-denaturing PAGE and 4–15% gradient SDS-PAGE followed by Western blot as well as by isolelectrofocusing and nephelometry. A total of 966 samples manifested percentages ≤ 2.8 or a double band in the alpha1-zone. According to the nephelometry data, 23 samples were classified as severe (A1AT ≤ 0.49 g/L) and 462 as intermediate (A1AT >0.49≤ 1.0 g/L) A1ATD. Twenty subjects agreed to complete the diagnosis and an additional 21 subjects agreed to family screening. We detected 9 cases with severe and 26 with intermediate A1ATD. Parallel experiments revealed that polymerization of M-type A1AT, when measured by nephelometry or isolelectrofocusing, yields inaccurate results, leading to the erroneous impression that it was Z type and not M-type A1AT. We illustrate the need for confirmation of Z A1AT values by “state of the art” method. Clinicians should consider a more in-depth investigation of A1ATD in patients when they exhibit serum polymers and low α1-globulin protein levels by SPE. PMID:26270547

  2. A CHANDRA OBSERVATION OF THE BURSTING MILLISECOND X-RAY PULSAR IGR J17511-3057

    Energy Technology Data Exchange (ETDEWEB)

    Paizis, A. [Istituto Nazionale di Astrofisica, INAF-IASF, Via Bassini 15, 20133 Milano (Italy); Nowak, M. A. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics, Cambridge, MA 02139 (United States); Rodriguez, J.; Chaty, S. [Astrophysique, Instrumentation et Modelisation (AIM, UMR-E 9005 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d' Astrophysique, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Wilms, J. [Dr. Karl Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics, Universitaet Erlangen-Nuernberg, Sternwartstr. 7, 96049 Bamberg (Germany); Del Santo, M.; Ubertini, P., E-mail: ada@iasf-milano.inaf.it, E-mail: mnowak@space.mit.edu [IAPS, INAF, Via Fosso del Cavaliere 100, 00133 Rome (Italy)

    2012-08-10

    IGR J17511-3057 is a low-mass X-ray binary hosting a neutron star and is one of the few accreting millisecond X-ray pulsars with X-ray bursts. We report on a 20 ks Chandra grating observation of IGR J17511-3057, performed on 2009 September 22. We determine the most accurate X-ray position of IGR J17511-3057, {alpha}{sub J2000} = 17{sup h}51{sup m}08.{sup s}66, {delta}{sub J2000} = -30 Degree-Sign 57'41.''0 (90% uncertainty of 0.''6). During the observation, a {approx}54 s long type-I X-ray burst is detected. The persistent (non-burst) emission has an absorbed 0.5-8 keV luminosity of 1.7 Multiplication-Sign 10{sup 36} erg s{sup -1} (at 6.9 kpc) and can be well described by a thermal Comptonization model of soft, {approx}0.6 keV, seed photons upscattered by a hot corona. The type-I X-ray burst spectrum, with average luminosity over the 54 s duration L{sub 0.5-8{sub keV}} = 1.6 Multiplication-Sign 10{sup 37} erg s{sup -1}, can be well described by a blackbody with kT{sub bb} {approx} 1.6 keV and R{sub bb} {approx} 5 km. While an evolution in temperature of the blackbody can be appreciated throughout the burst (average peak kT{sub bb} = 2.5{sup +0.8}{sub -0.4} keV to tail kT{sub bb} = 1.3{sup +0.2}{sub -0.1} keV), the relative emitting surface shows no evolution. The overall persistent and type-I burst properties observed during the Chandra observation are consistent with what was previously reported during the 2009 outburst of IGR J17511-3057.

  3. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-Ray Pulsar 1E 1841-045

    Science.gov (United States)

    Lin, Lin; Kouveliotou, Chryssa; Gogus, Ersin; van der Horst, Alexander J.; Watts, Anna L.; Baring, Matthew G.; Kaneko, Yuki; Wijers, Ralph A. M. J.; Woods, Peter M.; Barthelmy, Scott; Burgess, J. Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D.; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    SWift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18 - 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 1038 erg, which is in the low side of SGR bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in IE 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  4. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-ray Pulsar 1E 1841-045

    CERN Document Server

    Lin, Lin; Gogus, Ersin; van der Horst, Alexander J; Watts, Anna L; Baring, Matthew G; Kaneko, Yuki; Wijers, Ralph A M J; Woods, Peter M; Barthelmy, Scott; Burgess, J Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    Swift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18-140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8 - 25)E38 erg, which is in the low side of SGR bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in 1E 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  5. Can scale-freeness offset delayed signal detection in neuronal networks?

    CERN Document Server

    Uzun, Rukiye; Perc, Matjaz

    2014-01-01

    First spike latency following stimulus onset is of significant physiological relevance. Neurons transmit information about their inputs by transforming them into spike trains, and the timing of these spike trains is in turn crucial for effectively encoding that information. Random processes and uncertainty that underly neuronal dynamics have been shown to prolong the time towards the first response in a phenomenon dubbed noise-delayed decay. Here we study whether Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise might have shorter response times to external stimuli just above threshold if placed on a scale-free network. We show that the heterogeneity of the interaction network may indeed eradicate slow responsiveness, but only if the coupling between individual neurons is sufficiently strong. Increasing the average degree also favors a fast response, but it is less effective than increasing the coupling strength. We also show that noise-delayed decay can be offset further by adjusting the fre...

  6. [Cellular and molecular mechanisms of radiation-induced brain injury: can peripheral markers be detected?].

    Science.gov (United States)

    Piskunov, A K; Nikitin, K V; Potapov, A A

    2015-01-01

    Investigation of the mechanisms of radiation-induced brain injury is a relevant fundamental objective of radiobiology and neuroradiology. Damage to the healthy brain tissue is the key factor limiting the application of radiation therapy in patients with nervous systems neoplasms. Furthermore, postradiation brain injury can be clinically indiscernible from continued tumor growth and requires differential diagnosis. Thus, there exists high demand for biomarkers of radiation effects on the brain in neurosurgery and radiobiology. These markers could be used for better understanding and quantifying the effects of ionizing radiation on brain tissues, as well as for elaborating personalized therapy. Despite the high demand, biomarkers of radiation-induced brain injury have not been identified thus far. The cellular and molecular mechanisms of the effect of ionizing radiation on the brain were analyzed in this review in order to identify potential biomarkers of radiation-induced injury to nervous tissue.

  7. Device for detecting gas contamination, which can be filtered out. Vorrichtung zur Erfassung von ausfilterbaren Gaskontaminationen

    Energy Technology Data Exchange (ETDEWEB)

    Keller, M.

    1986-04-10

    A filter disc is described, which is situated on a horizontal, compact turntable, which is moved over a suction head, whose suction lips act with appropriate holes or bores of the turntable. The suction head is pressed from below against the parallel turntable by a spring with a Cardan action. The turntable is preferably turned in steps with a certain cycle time, particularly according to a program, by a certain number of places with 'phase displaced' multiple rotation of the turntable for complete use of the filter surface. Instead of a filter disc, adsorber material can be provided to collect the contamination. An arrangement with a feed period of 1 to 2 days and three detectors is used for monitoring the radioactivity.

  8. The Fluence and Distance Distributions of Fast Radio Bursts

    CERN Document Server

    Vedantham, H K; Hallinan, G; Shannon, R

    2016-01-01

    Fast radio bursts (FRB) are millisecond-duration radio pulses with apparent extragalactic origins. All but two of the FRBs have been discovered using the Parkes dish which employs multiple beams formed by an array of feed horns on its focal plane. In this paper, we show that (i) the preponderance of multiple-beam detections, and (ii) the detection rates for varying dish diameters, can be used to infer the index $\\alpha$ of the cumulative fluence distribution function (the log$N$-log$F$ function: $\\alpha=1.5$ for a non-evolving population in a Euclidean universe). If all detected FRBs arise from a single progenitor population, multiple-beam FRB detection rates from the Parkes telescope yield the constraint $0.52<\\alpha<1.0$ with $90$% confidence. Searches at other facilities with different dish sizes refine the constraint to $0.66<\\alpha<0.96$. Our results favor FRB searches with smaller dishes, because for $\\alpha<1$, the gain in field-of-view for a smaller dish is more important than the reduc...

  9. Powerful GeV emission from a gamma-ray-burst shock wave scattering stellar photons

    CERN Document Server

    Giannios, Dimitrios

    2008-01-01

    The gamma-ray bursts of long duration are likely connected to the death of massive stars. The gamma-ray emission is believed to come from energy released internally in a flow that moves at ultrarelativistic speed. The fast flow drives a shock wave into the external medium leading to the afterglow emission. Most massive stars form in dense clusters, their high luminosity producing a very dense radiation field. Here, I explore the observational consequences of the interaction of the shocked external medium of the burst with the photon field of a nearby O star. I show that inverse Compton scattering of the stellar photons by electrons heated by the shock leads to powerful gamma-ray emission in the ~1-100 GeV range. This emission appears minutes to hours after the burst and can be easily detected by Cherenkov telescopes and likely with the GLAST satellite. This signal may have already been observed in GRB 940217 and can yield important information about the circumburst environment.

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

    Directory of Open Access Journals (Sweden)

    Alireza Shameli-Sendi

    2013-01-01

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

  11. The host galaxy of a fast radio burst.

    Science.gov (United States)

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

    2016-02-25

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

  12. Accretion Disk Signatures in Type I X-Ray Bursts: Prospects for Future Missions

    Science.gov (United States)

    Keek, L.; Wolf, Z.; Ballantyne, D. R.

    2016-07-01

    Type I X-ray bursts and superbursts from accreting neutron stars illuminate the accretion disk and produce a reflection signal that evolves as the burst fades. Examining the evolution of reflection features in the spectra will provide insight into the burst-disk interaction, a potentially powerful probe of accretion disk physics. At present, reflection has been observed during only two bursts of exceptional duration. We investigate the detectability of reflection signatures with four of the latest well-studied X-ray observatory concepts: Hitomi, Neutron Star Interior Composition Explorer (NICER), Athena, and Large Observatory For X-ray Timing (LOFT). Burst spectra are modeled for different values for the flux, temperature, and the disk ionization parameter, which are representative for most known bursts and sources. The effective area and throughput of a Hitomi-like telescope are insufficient for characterizing burst reflection features. NICER and Athena will detect reflection signatures in Type I bursts with peak fluxes ≳10-7.5 erg cm-2 s-1 and also effectively constrain the reflection parameters for bright bursts with fluxes of ˜10-7 erg cm-2 s-1 in exposures of several seconds. Thus, these observatories will provide crucial new insight into the interaction of accretion flows and X-ray bursts. For sources with low line-of-sight absorption, the wide bandpass of these instruments allows for the detection of soft X-ray reflection features, which are sensitive to the disk metallicity and density. The large collecting area that is part of the LOFT design would revolutionize the field by tracing the evolution of the accretion geometry in detail throughout short bursts.

  13. Nemesis, Tyche, Planet Nine Hypotheses. I. Can We Detect the Bodies Using Gravitational Lensing?

    Science.gov (United States)

    Philippov, J. P.; Chobanu, M. I.

    2016-08-01

    In this paper, the hypothesis of the existence of a massive dark body (Nemesis, Tyche, Planet Nine, or any other trans-Plutonian planet) at the Solar system periphery is analysed. Basic physical properties and orbital characteristics of such massive bodies are considered. The problem of the definition of a scattering angle of a photon in the gravitational field of a spherical lens is studied. It is shown that, the required value of the scattering angle can be measured for the cases of Nemesis and Tyche. The formation of gravitational lensing images is studied here for a point mass event. It is demonstrated that in most cases of the close rapprochement of a source and the lens (for Nemesis and Tyche), it is possible to resolve two images. The possibility of resolving these images is one of the main arguments favouring the gravitational lensing method as its efficiency in searching for dark massive objects at the edge of the Solar System is higher than the one corresponding to other methods such as stellar occultation. For the cases of Planet Nine and any other trans-Plutonian planet, the strong gravitational lensing is impossible because at least one of the images is always eclipsed.

  14. The submillimetre properties of gamma-ray burst host galaxies

    NARCIS (Netherlands)

    N.R. Tanvir; V.E. Barnard; A.W. Blain; A.S. Fruchter; C. Kouveliotou; P. Natarajan; E. Ramirez-Ruiz; E. Rol; I.A. Smith; R.P.J. Tilanus; R.A.M.J. Wijers

    2004-01-01

    Long-duration gamma-ray bursts (GRBs) accompany the deaths of some massive stars and hence, because massive stars are short-lived, are a tracer of star formation activity. Given that GRBs are bright enough to be seen to very high redshifts and detected even in dusty environments, they should therefo

  15. Can multidetector CT detect the site of gastrointestinal tract injury in trauma? – A retrospective study

    Science.gov (United States)

    Panda, Ananya; Kumar, Atin; Gamanagatti, Shivanand; Das, Ranjita; Paliwal, Swati; Gupta, Amit; Kumar, Subodh

    2017-01-01

    PURPOSE We aimed to assess the performance of computed tomography (CT) in localizing site of traumatic gastrointestinal tract (GIT) injury and determine the diagnostic value of CT signs in site localization. METHODS CT scans of 97 patients with surgically proven GIT or mesenteric injuries were retrospectively reviewed by radiologists blinded to surgical findings. Diagnosis of either GIT or mesenteric injuries was made. In patients with GIT injuries, site of injury and presence of CT signs such as focal bowel wall hyperenhancement, hypoenhancement, wall discontinuity, wall thickening, extramural air, intramural air, perivisceral infiltration, and active vascular contrast leak were evaluated. RESULTS Out of 97 patients, 90 had GIT injuries (70 single site injuries and 20 multiple site injuries) and seven had isolated mesenteric injury. The overall concordance between CT and operative findings for exact site localization was 67.8% (61/90), partial concordance rate was 11.1% (10/90), and discordance rate was 21.1% (19/90). For single site localization, concordance rate was 77.1% (54/70), discordance rate was 21.4% (15/70), and partial concordance rate was 1.4% (1/70). In multiple site injury, concordance rate for all sites of injury was 35% (7/20), partial concordance rate was 45% (9/20), and discordance rate was 20% (4/20). For upper GIT injuries, wall discontinuity was the most accurate sign for localization. For small bowel injury, intramural air and hyperenhancement were the most specific signs for site localization, while for large bowel injury, wall discontinuity and hypoenhancement were the most specific signs. CONCLUSION CT performs better in diagnosing small bowel injury compared with large bowel injury. CT can well predict the presence of multiple site injury but has limited performance in exact localization of all injury sites. PMID:27924777

  16. Adaptation to visual stimulation modifies the burst firing property of V1 neurons%Adaptation to visual stimulation modifies the burst firing property of V1neurons

    Institute of Scientific and Technical Information of China (English)

    Rui-Long LIU; Ke WANG; Jian-Jun MENG; Tian-Miao HUA; Zhen LIANG; Min-Min XI

    2013-01-01

    The mean firing rate of visual cortical neurons is reduced after prolonged visual stimulation,but the underlying process by which this occurs as well as the biological significance of this phenomenon remains unknown.Computational neuroscience studies indicate that high-frequency bursts in stimulus-driven responses can be transmitted across synapses more reliably than isolated spikes,and thus may carry accurate stimulus-related information.Our research examined whether or not adaptation affects the burst firing property of visual cortical neurons by examining changes in the burst firing changes of V1 neurons during adaptation to the preferred visual stimulus.The results show that adaptation to prolonged visual stimulation significantly decreased burst frequency (bursts/s) and burst length (spikes/burst),but increased burst duration and the interspike interval within bursts.These results suggest that the adaptation of V1 neurons to visual stimulation may result in a decrease of feedforward response gain but an increase of functional activities from lateral and/or feedback connections,which could lead to a reduction in the effectiveness of adapted neurons in transmitting information to its driven neurons.

  17. The Third Swift Burst Alert Telescope Gamma-Ray Burst Catalog

    CERN Document Server

    Lien, Amy; Barthelmy, Scott D; Baumgartner, Wayne H; Cannizzo, John K; Chen, Kevin; Collins, Nicholas R; Cummings, Jay R; Gehrels, Neil; Krimm, Hans A; Markwardt, Craig B; Palmer, David M; Stamatikos, Michael; Troja, Eleonora; Ukwatta, T N

    2016-01-01

    To date, the Burst Alert Telescope (BAT) onboard Swift has detected ~ 1000 gamma-ray bursts (GRBs), of which ~ 360 GRBs have redshift measurements, ranging from z = 0.03 to z = 9.38. We present the analyses of the BAT-detected GRBs for the past ~ 11 years up through GRB151027B. We report summaries of both the temporal and spectral analyses of the GRB characteristics using event data (i.e., data for each photon within approximately 250 s before and 950 s after the BAT trigger time), and discuss the instrumental sensitivity and selection effects of GRB detections. We also explore the GRB properties with redshift when possible. The result summaries and data products are available at http://swift.gsfc.nasa.gov/results/batgrbcat/index.html. In addition, we perform searches for GRB emissions before or after the event data using the BAT survey data. We estimate the false detection rate to be only one false detection in this sample. There are 15 ultra-long GRBs (~ 2% of the BAT GRBs) in this search with confirmed emi...

  18. Radio Bursts in the Active Period January 2005

    CERN Document Server

    Bouratzis, K; Hillaris, A; Moussas, X; Caroubalos, C; Petoussis, V; Tsitsipis, P; Kontogeorgos, A; 10.1063/1.2347980

    2010-01-01

    We present complex radio bursts recorded by the radiospectrograph ARTEMIS-IV in the active period of January 2005. The wide spectral coverage of this recorder, in the 650-20 MHz range, permits an analysis of the radio bursts from the base of the Solar Corona to 2 Solar Radii; it thus facilitates the association of radio activity with other types of solar energetic phenomena. Furthermore the ARTEMIS-IV1, high time resolution (1/100 sec) in the 450-270 MHz range, makes possible the detection and analysis of the fine structure which most of the major radio events exhibit.

  19. Cosmological Gamma-Ray Bursts and Hypernovae Conclusively Linked

    Science.gov (United States)

    2003-06-01

    of their outer layers, they consist almost purely of helium, oxygen and heavier elements produced by intense nuclear burning during the preceding phase of their short life. " We have been waiting for this one for a long, long time ", says Jens Hjorth , " this GRB really gave us the missing information. From these very detailed spectra, we can now confirm that this burst and probably other long gamma-ray bursts are created through the core collapse of massive stars. Most of the other leading theories are now unlikely. " A "type-defining event" His colleague, ESO-astronomer Palle Møller , is equally content: " What really got us at first was the fact that we clearly detected the supernova signatures already in the first FORS-spectrum taken only four days after the GRB was first observed - we did not expect that at all. As we were getting more and more data, we realised that the spectral evolution was almost completely identical to that of the hypernova seen in 1998. The similarity of the two then allowed us to establish a very precise timing of the present supernova event ". The astronomers determined that the hypernova explosion (designated SN 2003dh [2]) documented in the VLT spectra and the GRB-event observed by HETE-II must have occurred at very nearly the same time. Subject to further refinement, there is at most a difference of 2 days, and there is therefore no doubt whatsoever, that the two are causally connected. " Supernova 1998bw whetted our appetite, but it took 5 more years before we could confidently say, we found the smoking gun that nailed the association between GRBs and SNe " adds Chryssa Kouveliotou of NASA. " GRB 030329 may well turn out to be some kind of 'missing link' for GRBs. " In conclusion, GRB 030329 was a rare "type-defining" event that will be recorded as a watershed in high-energy astrophysics . What really happened on March 29 (or 2,650 million years ago)? Here is the complete story about GRB 030329, as the astronomers now read it

  20. Burst-properties as a function of mass accretion rate in GX 3+1

    CERN Document Server

    Den Hartog, P; Kuulkers, E; Cornelisse, R; Heisse, J; Bazzano, A; Cocchi, M; Natalucci, L; Ubertini, P

    2003-01-01

    GX 3+1 is a low-mass X-ray binary that is persistently bright since its discovery in 1964. It was found to be an X-ray burster twenty years ago proving that the compact object in this system is a neutron star. The burst rate is so low that only 18 bursts were reported prior to 1996. The Wide Field Cameras on BeppoSAX have, through a dedicated monitoring program on the Galactic center region, increased the number of X-ray bursts from GX 3+1 by 61. Since GX 3+1 exhibits a slow (order of years) modulation in the persistent flux of about 50%, these observations opens up the unique possibility to study burst properties as a function of mass accretion rate for very low burst rates. This is the first time that bursts are detected from GX 3+1 in the high state. From the analysis we learn that all bursts are short with e-folding decay times smaller than 10 s. Therefore, all bursts are due to unstable helium burning. Furthermore, the burst rate drops sixfold in a fairly narrow range of 2-20 keV flux; we discuss possibl...

  1. Measuring Ambient Densities and Lorentz Factors of Gamma-Ray Bursts from GeV and Optical Observations

    CERN Document Server

    Hascoët, Romain; Beloborodov, Andrei M

    2015-01-01

    Fermi satellite discovered that cosmological gamma-ray bursts (GRBs) are accompanied by long GeV flashes. In two GRBs, an optical counterpart of the GeV flash has been detected. Recent work suggests that the GeV+optical flash is emitted by the external blast wave from the explosion in a medium loaded with copious $e^\\pm$ pairs. The full light curve of the flash is predicted by a first-principle radiative transfer simulation and can be tested against observations. Here we examine a sample of 7 bursts with best GeV+optical data and test the model. We find that the observed light curves are in agreement with the theoretical predictions and allow us to measure three parameters for each burst: the Lorentz factor of the explosion, its isotropic kinetic energy, and the external density. With one possible exception of GRB 090510 (which is the only short burst in the sample) the ambient medium is consistent with a wind from a Wolf-Rayet progenitor. The wind density parameter $A=\\rho r^2$ varies in the sample around $1...

  2. Comparison of interplanetary type 2 radio burst observations by ISEE-3, Ulysses, and WIND with applications to space weather prediction

    Science.gov (United States)

    MacDowall, R. J.; Klimas, A. J.; Lengyel-Frey, D.; Stone, R. G.; Thejappa, G.

    1997-01-01

    Interplanetary (IP) type 2 radio bursts are produced by IP shocks driven by solar ejecta, presumably involving shock acceleration of electrons that leads to radio emission. These radio bursts, which can be detected remotely by a sensitive spacecraft radio receiver, provide a method of tracking the leading edge of solar ejecta moving outward from the sun. Consequently, observations of these bursts sometimes provide advance warning of one or more days prior to the onset of geomagnetic activity induced by the solar ejecta. A robust lower limit on the fraction of intense geomagnetic storms, that are preceded by IP type 2 bursts, is provided. It is shown that 41 percent of the geomagnetic storms occurring during the interval September 1978 to February 1983 were preceded by type 2 events in this catalog, and reasons why the fraction is not larger are addressed. Differences in the observing capabilities of the International Sun-Earth Explorer (ISEE) 3, Ulysses, and WIND, to explain why each of these similar spacecraft radio investigations provides a different perspective of IP type 2 emissions are reviewed.

  3. Theta burst stimulation reduces disability during the activities of daily living in spatial neglect.

    Science.gov (United States)

    Cazzoli, Dario; Müri, René M; Schumacher, Rahel; von Arx, Sebastian; Chaves, Silvia; Gutbrod, Klemens; Bohlhalter, Stephan; Bauer, Daniel; Vanbellingen, Tim; Bertschi, Manuel; Kipfer, Stefan; Rosenthal, Clive R; Kennard, Christopher; Bassetti, Claudio L; Nyffeler, Thomas

    2012-11-01

    Left-sided spatial neglect is a common neurological syndrome following right-hemispheric stroke. The presence of spatial neglect is a powerful predictor of poor rehabilitation outcome. In one influential account of spatial neglect, interhemispheric inhibition is impaired and leads to a pathological hyperactivity in the contralesional hemisphere, resulting in a biased attentional allocation towards the right hemifield. Inhibitory transcranial magnetic stimulation can reduce the hyperactivity of the contralesional, intact hemisphere and thereby improve spatial neglect symptoms. However, it is not known whether this improvement is also relevant to the activities of daily living during spontaneous behaviour. The primary aim of the present study was to investigate whether the repeated application of continuous theta burst stimulation trains could ameliorate spatial neglect on a quantitative measure of the activities of daily living during spontaneous behaviour. We applied the Catherine Bergego Scale, a standardized observation questionnaire that can validly and reliably detect the presence and severity of spatial neglect during the activities of daily living. Eight trains of continuous theta burst stimulation were applied over two consecutive days on the contralesional, left posterior parietal cortex in patients suffering from subacute left spatial neglect, in a randomized, double-blind, sham-controlled design, which also included a control group of neglect patients without stimulation. The results showed a 37% improvement in the spontaneous everyday behaviour of the neglect patients after the repeated application of continuous theta burst stimulation. Remarkably, the improvement persisted for at least 3 weeks after stimulation. The amelioration of spatial neglect symptoms in the activities of daily living was also generally accompanied by significantly better performance in the neuropsychological tests. No significant amelioration in symptoms was observed after sham

  4. Keck Observations of 160 Gamma-Ray Burst Host Galaxies

    CERN Document Server

    Perley, Daniel A; Prochaska, Jason X

    2013-01-01

    We present a preliminary data release from our multi-year campaign at Keck Observatory to study the host galaxies of a large sample of Swift-era gamma-ray bursts via multi-color ground-based optical imaging and spectroscopy. With over 160 targets observed to date (and almost 100 host detections, most of which have not previously been reported in the literature) our effort represents the broadest GRB host survey to date. While targeting was heterogeneous, our observations span the known diversity of GRBs including short bursts, long bursts, spectrally soft GRBs (XRFs), ultra-energetic GRBs, X-ray faint GRBs, dark GRBs, SN-GRBs, and other sub-classes. We also present a preview of our database (currently available online via a convenient web interface) including a catalog of multi-color photometry, redshifts and line ID's. Final photometry and reduced imaging and spectra will be available in the near future.

  5. A novel optical burst switching architecture for high speed networks

    Institute of Scientific and Technical Information of China (English)

    Amit Kumar Garg; R. S. Kaler

    2008-01-01

    A novel optical burst switching (OBS) high speed network architecture has been proposed. To verify its feasibility and evaluate its performance, just-enough-time (JET) signaling has been considered as a high performance protocol. In the proposed architecture, to avoid burst losses, firstly, a short-priorconfirrnation-packet (SPCP) is sent over the control channel that simulates the events that the actual packet will experience. Once SPCP detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeats. In order to increase network utilization, cost effectiveness and to overcome some limitations of conventional OBS, inherent codes (e.g., orthogonal optical codes (OOC)),which are codified only in intensity, has been used. Through simulations, it shows that a decrease in burst loss probability, cost effectiveness and a gain in processing time are obtained when optical label processing is used as compared with electronic processing.

  6. Prompt Optical Observations of $\\gamma$-ray Bursts

    CERN Document Server

    Akerlof, Carl W; Barthelmy, S D; Bloch, J; Butterworth, P S; Casperson, D E; Cline, T; Fletcher, S; Frontera, F; Gisler, G; Heise, J; Hills, J; Hurley, K; Kehoe, R; Lee, B; Marshall, S; McKay, T; Pawl, A; Piro, L; Szymanski, J J; Wren, J; Akerlof, Carl; Balsano, Richard; Barthelmy, Scott; Bloch, Jeff; Butterworth, Paul; Casperson, Don; Cline, Tom; Fletcher, Sandra; Frontera, Fillippo; Gisler, Galen; Heise, John; Hills, Jack; Hurley, Kevin; Kehoe, Robert; Lee, Brian; Marshall, Stuart; Kay, Tim Mc; Pawl, Andrew; Piro, Luigi; Szymanski, John; Wren, Jim

    2000-01-01

    The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 square degree or better produced no detections. The earliest limiting sensitivity is m(ROTSE) > 13.1 at 10.85 seconds (5 second exposure) after the gamma-ray rise, and the best limit is m(ROTSE) > 16.0 at 62 minutes (897 second exposure). These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. Consideration of the gamma-ray fluence and peak flux for these bursts and for GRB990123 indicates that there is not a strong positive correlation between optical flux and gamma-ray emission.

  7. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    CERN Document Server

    Lin, Lin; Baring, Matthew G; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT Windowed Timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5 - 200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT/GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbo...

  8. Importance of greenstick lamina fractures in low lumbar burst fractures

    Science.gov (United States)

    Ersozlu, S.; Aydinli, U.

    2006-01-01

    Lumbar burst fractures (L3–L5) represent a small percentage of all spinal fractures. The treatment of fractures involving the lumbar spine has been controversial. Lamina fractures may be complete or of the greenstick type. Dural tears and nerve root entrapment may accompany these lamina fractures. The aim of this retrospective study was to determine the incidence of dural tear in patients who had lumbar burst fractures with greenstick lamina fractures and the importance of these lamina fractures when choosing the optimum treatment. Twenty-six patients with 28 lumbar burst fractures were treated from 1995 through 2002. The average follow-up was 60 months (range 32–110 months). The male to female ratio was 21:5 and the mean age was 37 years (17–64). Dural tear was detected in seven (25%) out of 28 burst fractures. The functional outcome of the entire study group was assessed using the Smiley-Webster Scale. Good to excellent results were obtained in 24 (92%) of 26 patients. Lumbar burst fractures with greenstick lamina fractures occur mostly in the L2–L4 area. In the surgical treatment, any reduction manoeuvre will close the fracture and crush the entrapped neural elements. Therefore, it may be better to explore the greenstick lamina fracture whether there is any neural entrapment or not, before any reduction manoeuvre is attempted. PMID:16501977

  9. Can-rupture detection in gas-cooled nuclear reactors; La detection des ruptures de gaine dans les piles nucleaires refroidies par gaz

    Energy Technology Data Exchange (ETDEWEB)

    Roguin, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    Can-rupture detection (DRG) is one important aspect of pile safety, more particularly so in the case of gas-cooled reactors. A rapid and sure detection constitutes also an improvement as far as the efficiency of electricity-producing nuclear power stations are concerned. Among the numerous can-rupture detection methods, that based on the measurement of the concentration of short-lived fission gases in the heat-carrying fluid has proved to be the most sensitive and the most rapid. A systematic study of detectors based on the electrostatic collection of the daughter products of fission gases has been undertaken with a view to equip the reactors EL 2, G 3, EDF 1, EDF 2 and EDF 3, the gas loops of PEGASE and EL 4. The different parameters are studied in detail in order to obtain a maximum sensitivity and to make it possible to construct detection devices having the maximum operational reliability and requiring the minimum maintenance. The primary applications of these devices are examined in the case of the above-mentioned reactors. (author) [French] La Detection des Ruptures de Gaines (D. R. G.) est un aspect important de la securite des piles et plus particulierement des piles refroidies par un gaz. Une detection rapide et sure constitue aussi un element d'amelioration du rendement des centrales nucleaires productrices d'energie electrique. Parmi les nombreuses methodes de detection des ruptures de gaines, la mesure de la concentration dans le fluide caloporteur des gaz de fission a vie courte s'est revelee comme la plus sensible et la plus rapide. Une etude systematique des detecteurs a collection electrostatique des descendants des gaz de fission a ete entreprise en vue d'equiper les piles EL 2, G 3, EDF 1, EDF 2 et EDF 3, les boucles a gaz de la pile Pegase et la pile EL 4. Les divers parametres sont etudies en detail pour obtenir une sensibilite maximum et permettre la realisation de dispositifs de detection ayant le maximum de securite de

  10. The Escape of High-Energy Photons from Gamma-Ray Bursts

    CERN Document Server

    Baring, M G; Baring, Matthew G.; Harding, Alice K.

    1997-01-01

    Eleven bright gamma-ray bursts (GRBs) detected by BATSE have also been seen at much higher energies by EGRET, six at energies above 10 MeV. Such observations imply that these bursts are optically thin to photon-photon pair production at all observed energies. For bursts more than about 30pc away, internal transparency can be achieved only if the source is moving with a relativistic bulk Lorentz factor $\\Gamma\\gg 1$, or if the radiation is highly beamed. Early calculations of $\\gamma\\gamma\\to e^+e^-$ considerations for GRBs were limited to cases of a beam with opening half-angle $\\Thetab\\sim 1/\\Gamma$, or expansions of infinitely thin spherical shells. This paper presents our extension of pair production optical depth calculations in relativistically expanding sources to more general geometries, including shells of finite thickness and arbitrary opening angle. The problem is reduced analytically to a single integral in the broadly applicable case of observing photons along the axis of the expansion. We find th...

  11. Short Gamma-Ray Bursts from the Merger of Two Black Holes

    CERN Document Server

    Perna, Rosalba; Giacomazzo, Bruno

    2016-01-01

    Short Gamma-Ray Bursts (GRBs) are explosions of cosmic origin believed to be associated with the merger of two compact objects, either two neutron stars, or a neutron star and a black hole. The presence of at least one neutron star has long been thought to be an essential element of the model: its tidal disruption provides the needed baryonic material whose rapid accretion onto the post-merger black hole powers the burst. The recent tentative detection by the Fermi satellite of a short GRB in association with the gravitational wave signal GW150914 produced by the merger of two black holes has shaken this standard paradigm. Here we show that the evolution of two high-mass, low-metallicity stars with main sequence rotational speeds a few tens of percent of the critical speed eventually undergoing a weak supernova explosion {\\em can} produce a short gamma-ray burst. The outer layers of the envelope of the last exploding star remain bound and circularize at large radii. With time, the disk cools and becomes neutr...

  12. Dense magnetized plasma associated with a fast radio burst.

    Science.gov (United States)

    Masui, Kiyoshi; Lin, Hsiu-Hsien; Sievers, Jonathan; Anderson, Christopher J; Chang, Tzu-Ching; Chen, Xuelei; Ganguly, Apratim; Jarvis, Miranda; Kuo, Cheng-Yu; Li, Yi-Chao; Liao, Yu-Wei; McLaughlin, Maura; Pen, Ue-Li; Peterson, Jeffrey B; Roman, Alexander; Timbie, Peter T; Voytek, Tabitha; Yadav, Jaswant K

    2015-12-24

    Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models. One fast burst revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.

  13. 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 that...

  14. Theta, alpha and beta burst transcranial magnetic stimulation: brain modulation in tinnitus

    Directory of Open Access Journals (Sweden)

    Dirk De Ridder, Elsa van der Loo, Karolien Van der Kelen, Tomas Menovsky, Paul van de Heyning, Aage Moller

    2007-01-01

    Full Text Available Introduction: Some forms of tinnitus are considered to be auditory phantom phenomena related to reorganization and hyperactivity of the auditory central nervous system. Repetitive transcranial magnetic stimulation (rTMS is a non-invasive tool capable of modulating human brain activity, using single pulse or burst stimuli. Burst rTMS has only been performed in the theta range, and has not been used clinically. The authors analyze whether burst TMS at theta (5 Hz, alpha (10 Hz and beta (20 Hz frequencies can temporarily suppress narrow band noise/white noise tinnitus, which has been demonstrated to be intractable to tonic stimulation. Methods: rTMS is performed both in tonic and burst mode in 46 patients contralateral to the tinnitus side, at 5, 10 and 20 Hz. Fourteen placebo negative rTMS responders are further analyzed. Results: In 5 patients, maximal tinnitus suppression is obtained with theta, in 2 with alpha and in 7 with beta burst stimulation. Burst rTMS suppresses narrow band/white tinnitus much better than tonic rTMS t(13=6.4, p<.000. Women experience greater suppression of their tinnitus with burst stimulation than men, t(12=2.9, p<.05. Furthermore left sided tinnitus is perceived as more distressing on the TQ than right sided tinnitus, t(12=3.2, p<.01. The lower the tinnitus pitch the more effectively rTMS suppresses tinnitus(r=-0.65, p<0.05. Discussion: Burst rTMS can be used clinically, not only theta burst, but also alpha and beta burst. Burst rTMS is capable of suppressing narrow band/white noise tinnitus very much better than tonic rTMS. This could be due the simple fact that burst neuromodulation is more powerful than tonic neuromodulation or to a differential effect of burst and tonic stimulation on the lemniscal and extralemniscal auditory system. In some patients only alpha or beta burst rTMS is capable of suppressing tinnitus, and theta burst not. Therefore in future rTMS studies it could be worthwhile not to limit burst

  15. Decameter type III bursts with positive and negative frequency drift rates

    Science.gov (United States)

    Melnik, V. N.; Brazhenko, A. I.; Konovalenko, A. A.; Briand, C.; Dorovskyy, V. V.; Zarka, P.; Frantzusenko, A. V.; Rucker, H. O.; Rutkevych, B. P.; Panchenko, M.; Zaqarashvili, T.; Shergelashvili, B.

    2013-09-01

    We report about observations of decameter type III bursts whose frequency drift rates vary their signs from negative to positive. Moreover drift rates of some bursts vary the sign some times. Positive drift rates for some bursts are changed from 0.44 MHz/s to 12 MHz/s. At the same time the negative drift rates of these bursts are standard values for decameter type III bursts. A possible interpretation of such phenomenon on the base of plasma mechanism of type III burst generation is discussed. The sense of this interpretation is that group velocity of type III electromagnetic waves generated by fast electrons at some conditions can be smaller than velocity of these electrons.

  16. Characterizing a burst leading-edge vortex on a rotating flat plate wing

    Science.gov (United States)

    Jones, Anya R.; Medina, Albert; Spooner, Hannah; Mulleners, Karen

    2016-04-01

    Identifying, characterizing, and tracking incoherent vortices in highly separated flows is of interest for the development of new low-order models for unsteady lift prediction. The current work examines several methods to identify vortex burst and characterize a burst leading-edge vortex. Time-resolved stereoscopic PIV was performed on a rotating flat plate wing at Re = 2500. The burst process was found to occur at mid-span and is characterized by axial flow reversal, the entrainment of opposite-sign vorticity, and a rapid expansion of vortex size. A POD analysis revealed that variations in certain mode coefficients are indicative of the flow state changes characteristics of burst. During burst, the leading-edge vortex evolves to a region of inhomogeneous vorticity distributed over a large area. Several methods of defining the vortex size and circulation are evaluated and a combination of these can be used to characterize the leading-edge vortex both pre- and post-burst.

  17. Inferring the Distances of Fast Radio Bursts Through Associated 21-cm Absorption

    OpenAIRE

    Margalit, Ben; Loeb, Abraham

    2015-01-01

    The distances of Fast Radio Burst (FRB) sources are currently unknown. We show that the 21-cm absorption line of hydrogen can be used to infer the redshifts of FRB sources, and determine whether they are Galactic or extragalactic. We calculate a probability of $\\sim 10\\%$ for the host galaxy of an FRB to exhibit a 21-cm absorption feature of equivalent width $\\gtrsim 10 ~\\mathrm{km}~\\mathrm{s}^{-1}$. Arecibo, along with several future radio observatories, should be capable of detecting such a...

  18. 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.

  19. Accretion disk signatures in Type I X-ray Bursts: prospects for future missions

    CERN Document Server

    Keek, L; Ballantyne, D R

    2016-01-01

    Type I X-ray bursts and superbursts from accreting neutron stars illuminate the accretion disk and produce a reflection signal that evolves as the burst fades. Examining the evolution of reflection features in the spectra will give insight into the burst-disk interaction, a potentially powerful probe of accretion disk physics. At present, reflection has been observed during only two bursts of exceptional duration. We investigate the detectability of reflection signatures with four of the latest well-studied X-ray observatory concepts: Hitomi, NICER, Athena, and LOFT. Burst spectra are modeled for different values for the flux, temperature, and the disk ionization parameter, which are representative for most known bursts and sources. The effective area and through-put of a Hitomi-like telescope are insufficient for characterizing burst reflection features. NICER and Athena will detect reflection signatures in Type I bursts with peak fluxes $\\ge 10^{-7.5}$ erg cm$^{-2}$ s$^{-1}$, and also effectively constrain ...

  20. Femoro-acetabular impingement: can indirect MR arthrography be considered a valid method to detect endoarticular damage? A preliminary study.

    Science.gov (United States)

    Pozzi, Grazia; Stradiotti, Paola; Parra, Cleber Garcia; Zagra, Luigi; Sironi, Sandro; Zerbi, Alberto

    2009-01-01

    To assess the effectiveness of indirect Magnetic Resonance arthrography (i-MRa) in the detection of chondral and labral lesions related to femoro-acetabular impingement (FAI) a series of 21 hip joints in 17 patients with a clinical diagnosis of FAI were examined either with standard MR imaging, i-MRa and direct-MR arthrography (d-MRa). Sensitivity and accuracy of i-MRa in detecting chondral, labral and tardive lesions were calculated and compared with standard MR. The agreement in detecting endoarticular damage between i-MRa and d-MRa and the interobserver agreement was assessed by K statistic (p<0.05). Finally the presence of trocanteric bursitis was evaluated. I-MRa showed higher values of both sensivity and accuracy than standard MR in detecting chondral damage, with an increase to 92% for the first item and 95% for the second. The same was noticed in labrum evaluation with an increase to 88% and 90% respectively. The level of agreement between i-MRa and d-MRa in detection of chondral lesions was excellent, substantial for the labral damage and absolute for early osteoarthritic changes. An excellent interobserver agreement resulted in detection of both chondral and labral damages with i-MRa. In 6 hips (28,5%) we also found the presence of peri-trochanteric soft tissue inflammation that indicated the possibility of extrarticular involvement in FAI. Indirect-MRa can be considered a valid method of assessing endoarticular damage related to FAI, in comparison to d-MRa. It should be performed instead of standard MR if d-MRa is not available.

  1. Properties of $\\gamma$-Ray Burst Classes

    CERN Document Server

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

    2000-01-01

    The three gamma-ray burst (GRB) classes identified by statistical clustering analysis (Mukherjee et al. 1998) are examined using the pattern recognition algorithm C4.5 (Quinlan 1986). Although the statistical existence of Class 3 (intermediate duration, intermediate fluence, soft) is supported, the properties of this class do not need to arise from a distinct source population. Class 3 properties can easily be produced from Class 1 (long, high fluence, intermediate hardness) by a combination of measurement error, hardness/intensity correlation, and a newly-identified BATSE bias (the fluence duration bias). Class 2 (short, low fluence, hard) does not appear to be related to Class 1.

  2. Ultimate detectability of volatile organic compounds: how much further can we reduce their ambient air sample volumes for analysis?

    Science.gov (United States)

    Kim, Yong-Hyun; Kim, Ki-Hyun

    2012-10-02

    To understand the ultimately lowest detection range of volatile organic compounds (VOCs) in air, application of a high sensitivity analytical system was investigated by coupling thermal desorption (TD) technique with gas chromatography (GC) and time-of-flight (TOF) mass spectrometry (MS). The performance of the TD-GC/TOF MS system was evaluated using liquid standards of 19 target VOCs prepared in the range of 35 pg to 2.79 ng per μL. Studies were carried out using both total ion chromatogram (TIC) and extracted ion chromatogram (EIC) mode. EIC mode was used for calibration to reduce background and to improve signal-to-noise. The detectability of 19 target VOCs, if assessed in terms of method detection limit (MDL, per US EPA definition) and limit of detection (LOD), averaged 5.90 pg and 0.122 pg, respectively, with the mean coefficient of correlation (R(2)) of 0.9975. The minimum quantifiable mass of target analytes, when determined using real air samples by the TD-GC/TOF MS, is highly comparable to the detection limits determined experimentally by standard. In fact, volumes for the actual detection of the major aromatic VOCs like benzene, toluene, and xylene (BTX) in ambient air samples were as low as 1.0 mL in the 0.11-2.25 ppb range. It was thus possible to demonstrate that most target compounds including those in low abundance could be reliably quantified at concentrations down to 0.1 ppb at sample volumes of less than 10 mL. The unique sensitivity of this advanced analytical system can ultimately lead to a shift in field sampling strategy with smaller air sample volumes facilitating faster, simpler air sampling (e.g., use of gas syringes rather than the relative complexity of pumps or bags/canisters), with greatly reduced risk of analyte breakthrough and minimal interference, e.g., from atmospheric humidity. The improved detection limits offered by this system can also enhance accuracy and measurement precision.

  3. Search for gamma ray burst quasi simultaneous optical emission with BOOTES-1

    Science.gov (United States)

    Castro Cerón, J. M.; Castro-Tirado, A. J.; Soldán, J.; Hudec, R.; Bernas, M.; Páta, P.; Mateo Sanguino, T. J.; de Ugarte Postigo, A.; Berná, J. Á; Nekola, M.; Gorosabel, J.; de la Morena, B. A.; Más-Hesse, J. M.; Giménez, Á.; Torres Riera, J.

    The Burst Observer and Optical Transient Exploring System experiment (BOOTES) has been designed to provide an automatic real time observing response to the detection of Gamma Ray Bursts (GRBs). It achieves such response by using wide field cameras attached to small robotic telescopes and imaging in the B,I and R bands. To date we have obtained images for about 50 events with the Wide Field Camera (WFC), starting, in several ocasions, 3 minutes after the burst commenced. One of the last searches resulted in the detection of an optical transient, candidate to be the optical counterpart of the GRB 000313, although such relation has not been established to absolute certainty yet.

  4. Do the Fermi Gamma-Ray Burst Monitor and Swift Burst Alert Telescope see the Same Short Gamma-Ray Bursts?

    CERN Document Server

    Burns, Eric; Zhang, Bin-Bin; Lien, Amy; Briggs, Michael S; Goldstein, Adam; Pelassa, Veronique; Troja, Eleonora

    2015-01-01

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field-of-view, and that the Fermi GBM SGRB detection threshold remains flatter across its field-of-view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and...

  5. 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.

  6. $\\gamma$-Ray Bursts the Four Crises

    CERN Document Server

    Tavani, M

    1998-01-01

    We discuss some open problems concerning the origin and the emission mechanism of gamma-ray bursts (GRBs) in light of recent developments. If GRBs originate at extragalactic distances, we are facing four crises: (1) an energy crisis, models have to account for more than 10^{53} ergs of energy emitted in the gamma-ray energy band; (2) a spectral crisis, emission models have to account for the surprising `smoothness' of GRB broad-band spectra, with no indication of the predicted spectral `distorsions' caused by inverse Compton scattering in large radiation energy density media, and no evidence for beaming; (3) an afterglow crisis, relativistic shock models have to explain the complexity of the afterglow behavior, the longevity of optical transients detectable up to six months after the burst, the erratic behavior of the radio emission, and the lack of evidence for substantial beaming as indicated by recent searches for GRB afterglows in the X-ray band; (4) a population crisis, from data clearly indicating that ...

  7. Early-time observations of gamma-ray burst error boxes with the Livermore optical transient imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G G

    2000-08-01

    Despite the enormous wealth of gamma-ray burst (GRB) data collected over the past several years the physical mechanism which causes these extremely powerful phenomena is still unknown. Simultaneous and early time optical observations of GRBs will likely make an great contribution t o our understanding. LOTIS is a robotic wide field-of-view telescope dedicated to the search for prompt and early-time optical afterglows from gamma-ray bursts. LOTIS began routine operations in October 1996 and since that time has responded to over 145 gamma-ray burst triggers. Although LOTIS has not yet detected prompt optical emission from a GRB its upper limits have provided constraints on the theoretical emission mechanisms. Super-LOTIS, also a robotic wide field-of-view telescope, can detect emission 100 times fainter than LOTIS is capable of detecting. Routine observations from Steward Observatory's Kitt Peak Station will begin in the immediate future. During engineering test runs under bright skies from the grounds of Lawrence Livermore National Laboratory Super-LOTIS provided its first upper limits on the early-time optical afterglow of GRBs. This dissertation provides a summary of the results from LOTIS and Super-LOTIS through the time of writing. Plans for future studies with both systems are also presented.

  8. Pseudomonas aeruginosa can be detected in a polymicrobial competition model using impedance spectroscopy with a novel biosensor.

    Directory of Open Access Journals (Sweden)

    Andrew C Ward

    Full Text Available Electrochemical Impedance Spectroscopy (EIS is a powerful technique that can be used to elicit information about an electrode interface. In this article, we highlight six principal processes by which the presence of microorganisms can affect impedance and show how one of these--the production of electroactive metabolites--changes the impedance signature of culture media containing Pseudomonas aeruginosa. EIS, was used in conjunction with a low cost screen printed carbon sensor to detect the presence of P. aeruginosa when grown in isolation or as part of a polymicrobial infection with Staphylococcus aureus. By comparing the electrode to a starting measurement, we were able to identify an impedance signature characteristic of P. aeruginosa. Furthermore, we are able to show that one of the changes in the impedance signature is due to pyocyanin and associated phenazine compounds. The findings of this study indicate that it might be possible to develop a low cost sensor for the detection of P. aeruginosa in important point of care diagnostic applications. In particular, we suggest that a development of the device described here could be used in a polymicrobial clinical sample such as sputum from a CF patient to detect P. aeruginosa.

  9. The Interplanetary Network Supplement to the HETE-2 Gamma-Ray Burst Catalog

    CERN Document Server

    Hurley, K; Barraud, C; Pelangeon, A; Boër, M; Vanderspek, R; Ricker, G; Mazets, E; Golenetskii, S; Frederiks, D D; Pal'shin, V D; Aptekar, R L; Smith, D M; Wigger, C; Hajdas, W; Rau, A; Von Kienlin, A; Mitrofanov, I G; Golovin, D V; Kozyrev, A S; Litvak, M L; Sanin, A B; Boynton, W; Fellows, C; Barthelmy, K Harshman S; Cline, T; Cummings, J; Gehrels, N; Krimm, H; Yamaoka, K; Ohno, M; Fukazawa, Y; Hanabata, Y; Takahashi, T; Tashiro, M; Terada, Y; Murakami, T; Makishima, K; Guidorzi, C; Frontera, F; Montanari, C E; Rossi, F; Trombka, J; McClanahan, T; Goldsten, R Starr J; Gold, R

    2009-01-01

    Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the FREGATE experiment aboard the HETE-II spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 154 bursts were obtained. We present the IPN localization data on these events.

  10. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE HETE-2 GAMMA-RAY BURST CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Atteia, J.-L.; Barraud, C.; Pelangeon, A. [IRAP, Universite de Toulouse, CNRS, 14, avenue Edouard Belin, F-31400 Toulouse (France); Boeer, M. [Observatoire de Haute-Provence, 04870 Saint Michel l' Observatoire (France); Vanderspek, R.; Ricker, G. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Mazets, E.; Golenetskii, S.; Frederiks, D. D.; Pal' shin, V. D.; Aptekar, R. L. [Ioffe Physico-Technical Institute of the Russian Academy of Sciences, St. Petersburg, 194021 (Russian Federation); Smith, D. M. [Physics Department and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Wigger, C.; Hajdas, W. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Rau, A.; Von Kienlin, A. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, Garching 85748 (Germany); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S., E-mail: khurley@ssl.berkeley.edu [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); and others

    2011-12-01

    Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High Energy Transient Experiment 2 spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 157 bursts were obtained. We present the IPN localization data on these events.

  11. An internally consistent gamma ray burst time history phenomenology

    Science.gov (United States)

    Cline, T. L.

    1985-01-01

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

  12. Localising fast radio bursts and other transients using interferometric arrays

    CERN Document Server

    Obrocka, Monika; Wilkinson, Peter

    2015-01-01

    A new population of sources emitting fast and bright transient radio bursts has recently been identified. The observed large dispersion measure values of FRBs suggests an extragalactic origin and an accurate determination of their positions and distances will provide an unique opportunity to study the magneto-ionic properties of the IGM. So far, FRBs have all been found using large dishes equipped with multi-pixel arrays. While large single dishes are well-suited for the discovery of transient sources they are poor at providing accurate localisations. A 2D snapshot image of the sky, made with a correlation interferometer array, can provide an accurate localisation of many compact radio sources simultaneously. However, the required time resolution to detect FRBs and a desire to detect them in real time, makes this currently impractical. In a beamforming approach, where many narrow tied-array beams are produced, the advantages of single dishes and interferometers can be combined. We present a proof-of-concept a...

  13. Can the detection of misery perfusion in chronic cerebrovascular disease be based on reductions in baseline CBF and vasoreactivity?

    Energy Technology Data Exchange (ETDEWEB)

    Okazawa, Hidehiko; Kobayashi, Masato; Pagani, Marco; Yonekura, Yoshiharu [University of Fukui, Biomedical Imaging Research Center, Matcuoka-cho, Fukui (Japan); Tsuchida, Tatsuro [Faculty of Medical Sciences, University of Fukui, Department of Radiology, Fukui (Japan); Arai, Yoshikazu; Isozaki, Makoto [University of Fukui, Department of Neurosurgery, Faculty of Medical Sciences, Fukui (Japan)

    2007-01-15

    The aim of this study was to clarify whether decreases in baseline regional cerebral blood flow (rCBF) and in residual cerebral vasoreactivity (CVR), assessed by the acetazolamide (ACZ) challenge, can detect misery perfusion in patients with chronic cerebrovascular disease (CVD). Oxygen extraction fraction (OEF) and other haemodynamic parameters were measured in 115 patients (64{+-}9 years old) with unilateral cerebrovascular steno-occlusive disease (>70% stenosis) using {sup 15}O-gas and water PET. A significant elevation of OEF, by greater than the mean+2SD compared with healthy controls, was defined as misery perfusion. CBF, CVR determined by percent change in CBF after ACZ administration, OEF and other haemodynamic parameters in the territories of the bilateral middle cerebral arteries were analysed. Diagnostic accuracy for the detection of misery perfusion using the criteria determined by baseline CBF and CVR was evaluated in all patients and in only those patients with occlusive lesions. Ten of 24 patients with misery perfusion showed a significant reduction in CVR. Using criteria determined by significant decreases in CVR and baseline CBF, misery perfusion was detected with a sensitivity of 42% and a specificity of 95% in all patients. In patients with occlusive lesions (n=50), sensitivity was higher but specificity was slightly lower. The diagnostic accuracy of the threshold determined by baseline CBF alone was similar in all patients and in only those patients with occlusive lesions, and was higher than that achieved using the asymmetry index of OEF. Reductions in CVR and baseline CBF in the ACZ challenge for CVD would detect misery perfusion with high specificity. Reduction in baseline rCBF is more accurate than reduction in CVR alone for the detection of misery perfusion. (orig.)

  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

    by the primary instrument LAD (Large Area Detector), sensitive to X-rays from 2 to 50 keV, offering a very large effective area (>10 m 2 ), but a small field of view ({\\o}{\\pi} sr), the WFM actually detects all types of transient sources, including Gamma-Ray Bursts (GRBs), which are of primary interest......The ESA M3 candidate mission LOFT (Large Observatory For x-ray Timing) has been designed to study strong gravitational fields by observing compact objects, such as black-hole binaries or neutron-star systems and supermassive black-holes, based on the temporal analysis of photons collected...

  15. Aphids preserved in propylene glycol can be used for reverse transcription-polymerase chain reaction detection of Potato virus Y.

    Science.gov (United States)

    Nie, Xianzhou; Pelletier, Yvan; Mason, Nicola; Dilworth, Andrea; Giguère, Marie-Andrée

    2011-08-01

    The effectiveness of propylene glycol on the retention of RNA target of Potato virus Y (PVY), an aphid stylet-borne virus, in Myzus persicae was investigated in comparison to ethanol and liquid nitrogen/-80°C. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the PVY targets from the propylene glycol/ethanol/liquid nitrogen preserved single aphids after a 5min acquisition period from infected potato plants. In the liquid nitrogen/-80°C and 70% ethanol treatments, 55.6% and 38.8% aphids tested PVY-positive, respectively. In the 0-75% propylene glycol treatments, 12.2-44.7% aphids tested PVY-positive. The lowest detection rate was in the 0% (positive rate, 15.2%) and the 10% propylene glycol (positive rate, 12.2%). As the propylene glycol concentration increased to 25%, 29.8% aphids tested positive. A high PVY-positive rate was also found in 35-75% propylene glycol treatments at 44.7% (35% propylene glycol), 36.7% (50% propylene glycol) and 34.8% (75% propylene glycol), which is comparable to the rate shown in 70% ethanol. No significant difference in the positive detection rate was observed in aphids preserved in 50% propylene glycol at room temperature for 2, 4 and 10 days. These results demonstrate that propylene glycol at 25-75% can retain PVY targets effectively in aphids for an extended time period, and thus can be used in aphid traps to preserve viruliferous aphids for later RT-PCR detection of PVY.

  16. Relativistic Precessing Jets and Cosmological $\\gamma$ Ray Bursts

    CERN Document Server

    Blackman, E G; Field, G B; Blackman, Eric G.; Yi, Insu; Field, George B.

    1996-01-01

    We discuss the possibility that gamma-ray bursts may result from cosmological relativistic blob emitting neutron star jets that precess past the line of sight. Beaming reduces the energy requirements, so that the jet emission can last longer than the observed burst duration. One precession mode maintains a short duration time scale, while a second keeps the beam from returning to the line of sight, consistent with the paucity of repeaters. The long life of these objects reduces the number required for production as compared to short lived jets. Blobs can account for the time structure of the bursts. Here we focus largely on kinematic and time scale considerations of beaming, precession, and blobs--issues which are reasonably independent of the acceleration and jet collimation mechanisms. We do suggest that large amplitude electro-magnetic waves could be a source of blob acceleration.

  17. A Faint, Steep Spectum Burst from the Radio Transient GCRT J1745-3009

    CERN Document Server

    Hyman, S D; Pal, S; Lazio, T J W; Ray, P S; Kassim, N E; Bhatnagar, S; Hyman, Scott D.; Roy, Subhashis; Pal, Sabyasachi; Ray, Paul S.; Kassim, Namir E.; Bhatnagar, Sanjay

    2007-01-01

    GCRT J1745-3009 is a transient bursting radio source located in the direction of the Galactic center. It was discovered in a 330 MHz VLA observation from 2002 September 30--October 1 and subsequently rediscovered in a 330 MHz GMRT observation from 2003 September 28 by Hyman et al. Here we report a new radio detection of the source in 330 MHz GMRT data taken on 2004 March 20. The observed properties of the single burst detected differ significantly from those measured previously, suggesting that GCRT J1745-3009 was detected in a new physical state. The 2004 flux density was ~0.05 Jy, ~10x weaker than the single 2003 burst and ~30x weaker than the five bursts detected in 2002. We derive a very steep spectral index, alpha = -13.5 +/- 3.0, across the bandpass, a new result previously not detectable due to limitations in the analysis of the 2002 and 2003 observations. Also, the burst was detected for only ~2 min., in contrast to the 10 min. duration observed in the earlier bursts. Due to sparse sampling, only the ...

  18. Maxi observations of long X-ray bursts

    CERN Document Server

    Serino, Motoko; Tamagawa, Toru; Sakamoto, Takanori; Nakahira, Satoshi; Matsuoka, Masaru; Yamaoka, Kazutaka; Negoro, Hitoshi

    2016-01-01

    We report nine long X-ray bursts from neutron stars, detected with Monitor of All-sky X-ray Image (MAXI). Some of these bursts lasted for hours, and hence are qualified as superbursts, which are prolonged thermonuclear flashes on neutron stars and are relatively rare events. MAXI observes roughly 85% of the whole sky every 92 minutes in the 2-20 keV energy band, and has detected nine bursts with a long e-folding decay time, ranging from 0.27 to 5.2 hours, since its launch in 2009 August until 2015 August. The majority of the nine events were found to originate from transient X-ray sources. The persistent luminosities of the sources, when these prolonged bursts were observed, were lower than 1% of the Eddington luminosity for five of them and lower than 20% for the rest. This trend is contrastive to the 18 superbursts observed before MAXI, all but two of which originated from bright persistent sources. The distribution of the total emitted energy, i.e., the product of e-folding time and luminosity, of these bu...

  19. Dense magnetized plasma associated with a fast radio burst

    CERN Document Server

    Masui, Kiyoshi; Sievers, Jonathan; Anderson, Christopher J; Chang, Tzu-Ching; Chen, Xuelei; Ganguly, Apratim; Jarvis, Miranda; Kuo, Cheng-Yu; Li, Yi-Chao; Liao, Yu-Wei; McLaughlin, Maura; Pen, Ue-Li; Peterson, Jeffrey B; Roman, Alexander; Timbie, Peter T; Voytek, Tabitha; Yadav, Jaswant K

    2015-01-01

    Fast Radio Bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1. These parameters are consistent with a wide range of source models. One fast radio burst showed circular polarization [21(7)%] of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in a newly detected burst - FRB 110523. It has radio flux at least 0.6 Jy and dispersion measure 623.30(5) pc cm$^{-3}$. Using Galactic contribution 45 pc cm$^{-3}$ and a model of intergalactic electron density, we place the s...

  20. Sensitivity of HAWC to Primordial Black Hole Bursts

    CERN Document Server

    Ukwatta, T N; MacGibbon, D Stump J H; Marinelli, S S; Yapici, T; Tollefson, K

    2015-01-01

    Primordial Black Holes (PBHs) are black holes that may have been created in the early Universe and could be as large as supermassive black holes or as small as the Planck scale. It is believed that a black hole has a temperature inversely proportional to its mass and will thermally emit all species of fundamental particles. PBHs with initial masses of 5.0 x 10^14 g should be expiring today with bursts of high-energy gamma radiation in the GeV/TeV energy range. The High Altitude Water Cherenkov (HAWC) observatory is sensitive to the high end of the PBH gamma-ray burst spectrum. Due to its large field of view, duty cycle above 90% and sensitivity up to 100 TeV, the HAWC observatory is well suited to perform a search for PBH bursts. We report that if the PBH explodes within 0.25 light years from Earth and within 26 degrees of zenith, HAWC will have a 95% probability of detecting the PBH burst at the 5 sigma level. Conversely, a null detection from a 2 year or longer HAWC search will set PBH upper limits which ar...

  1. The Burst Alert Telescope (BAT) on the Swift MIDEX Mission

    CERN Document Server

    Barthelmy, S D; Cummings, J R; Fenimore, E E; Gehrels, N; Hullinger, D; Krimm, H A; Markwardt, C B; Palmer, D M; Parsons, A; Sato, G; Suzuki, M; Takahashi, T; Tashiro, M; Tüller, J

    2005-01-01

    The Burst Alert Telescope (BAT) is one of 3 instruments on the Swift MIDEX spacecraft to study gamma-ray bursts (GRBs). The BAT first detects the GRB and localizes the burst direction to an accuracy of 1-4 arcmin within 20 sec after the start of the event. The GRB trigger initiates an autonomous spacecraft slew to point the two narrow field-of-view (FOV) instruments at the burst location within 20-70 sec so to make follow-up x-ray and optical observations. The BAT is a wide-FOV, coded-aperture instrument with a CdZnTe detector plane. The detector plane is composed of 32,768 pieces of CdZnTe (4x4x2mm), and the coded-aperture mask is composed of approximately 52,000 pieces of lead (5x5x1mm) with a 1-m separation between mask and detector plane. The BAT operates over the 15-150 keV energy range with approximately 7 keV resolution, a sensitivity of approximately 10E-8 erg*cm^-2*s^-1, and a 1.4 sr (half-coded) FOV. We expect to detect >100 GRBs/yr for a 2-year mission. The BAT also performs an all-sky hard x-ray s...

  2. Swift/BAT and Fermi/GBM observations of SGR J1935+2154 bursts

    Science.gov (United States)

    Lin, Lin

    2016-07-01

    SGR J1935+2154 is a new member of the magnetar family. It was discovered from a short burst which triggered Swift/BAT on 2014 July 5. In 2015 February, the source was detected in the burst active episode again which lasted for about 11 days. We searched for magnetar burst using Bayesian Blocks method through Swift/BAT and Fermi/GBM observations, and totally found 27 events including 3 in 2014 and 24 in 2015. In this talk we will present the result of our detailed analysis of the temporal and spectral properties of these short bursts, and briefly discuss the connection between burst activity and the persistent emission of the source.

  3. Gamma-ray bursts as the death throes of massive binary stars

    CERN Document Server

    Narayan, R; Piran, T

    1992-01-01

    It is proposed that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Bursts with complex profiles and relatively long durations are the result of magnetic flares generated by the Parker instability in a post-merger differentially-rotating disk. Some bursts may also be produced through neutrino-antineutrino annihilation into electrons and positrons. In both cases, an optically thick fireball of size $\\sles\\ 100$ km is initially created, which expands ultrarelativistically to large radii before radiating. Several previous objections to the cosmological merger model are eliminated. It is predicted that $\\gamma$-ray bursts will be accompanied by a burst of gravitational radiation from the spiraling-in binary which could be detected by LIGO.

  4. Gamma-ray bursts from massive Population III stars: clues from the radio band

    CERN Document Server

    Burlon, D; Ghirlanda, G; Hancock, P J; Parry, R; Salvaterra, R

    2016-01-01

    Current models suggest gamma-ray bursts could be used as a way of probing Population III stars - the first stars in the early Universe. In this paper we use numerical simulations to demonstrate that late time radio observations of gamma-ray burst afterglows could provide a means of identifying bursts that originate from Population III stars, if these were highly massive, independently from their redshift. We then present the results from a pilot study using the Australia Telescope Compact Array at 17 GHz, designed to test the hypothesis that there may be Population III gamma-ray bursts amongst the current sample of known events. We observed three candidates plus a control gamma-ray burst, and make no detections with upper limits of 20-40 uJy at 500-1300 days post explosion.

  5. Gamma-ray bursts from massive Population-III stars: clues from the radio band

    Science.gov (United States)

    Burlon, D.; Murphy, T.; Ghirlanda, G.; Hancock, P. J.; Parry, R.; Salvaterra, R.

    2016-07-01

    Current models suggest gamma-ray bursts could be used as a way of probing Population-III stars - the first stars in the early Universe. In this paper, we use numerical simulations to demonstrate that late-time radio observations of gamma-ray burst afterglows could provide a means of identifying bursts that originate from Population-III stars, if these were highly massive, independently from their redshift. We then present the results from a pilot study using the Australia Telescope Compact Array at 17 GHz, designed to test the hypothesis that there may be Population-III gamma-ray bursts amongst the current sample of known events. We observed three candidates plus a control gamma-ray burst, and make no detections with upper limits of 20-40 μJy at 500-1300 d post-explosion.

  6. Possibility of observing high energy neutrinos from gamma bursts, with the Antanares telescope, feasibility study; Possibilite d'observation, par le telescope antares, de neutrinos de haute energie associes aux sursauts gamma et validation des techniques de detection a l'aide d'un prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kouchner, A

    2001-04-01

    The European Antares collaboration intends to build a deep-sea neutrino telescope with a detection surface of about 1/10 km{sup 2} in the Mediterranean sea. The universe is transparent to neutrinos, so their study provides a unique means of improving our knowledge of the nature and origin of cosmic rays and their emission from the most powerful astrophysical sources in the cosmos. Neutrinos also offer the possibility of opening a new energy window (E>TeV) for observation of the universe. The first part of the thesis is dedicated to a study of the possibility of using the future telescope to look for correlations between gamma-ray bursts and high-energy neutrinos. It is based, on one hand, on the predictions of neutrino fluxes from gamma-ray bursts in the framework of the theoretical model of 'fireballs', and, on the other hand, on the temporal properties of the gamma-ray bursts in the 4. BATSE catalogue. The second part of the thesis presents the results obtained with a prototype detector line deployed, at the end of 1999, some forty km south-west off Marseilles. The objective was to operate a complete apparatus, similar to the future detector lines, from the shore, and under realistic conditions. Data from 7 photomultiplier tubes disposed along the detector line were transmitted through 37 km of optical fiber to the shore, where they were used to reconstruct tracks due to atmospheric muons, thus validating the detection principles and methods. (author)

  7. Spindle Bursts in Neonatal Rat Cerebral Cortex

    Directory of Open Access Journals (Sweden)

    Jenq-Wei Yang

    2016-01-01

    Full Text Available 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.

  8. 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.

  9. Fast radio burst discovered in the Arecibo pulsar ALFA survey

    Energy Technology Data Exchange (ETDEWEB)

    Spitler, L. G.; Freire, P. C. C.; Lazarus, P.; Lee, K. J. [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany); Cordes, J. M.; Chatterjee, S.; Wharton, R. S.; Brazier, A. [Department of Astronomy and Space Sciences, Cornell University, Ithaca, NY 14853 (United States); Hessels, J. W. T. [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Lorimer, D. R.; McLaughlin, M. A. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (United States); Kaspi, V. M.; Karako-Argaman, C. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Allen, B. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Jenet, F. A. [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Knispel, B., E-mail: lspitler@mpifr-bonn.mpg.de [Leibniz Universität, Hannover, D-30167 Hannover (Germany); and others

    2014-08-01

    Recent work has exploited pulsar survey data to identify temporally isolated, millisecond-duration radio bursts with large dispersion measures (DMs). These bursts have been interpreted as arising from a population of extragalactic sources, in which case they would provide unprecedented opportunities for probing the intergalactic medium; they may also be linked to new source classes. Until now, however, all so-called fast radio bursts (FRBs) have been detected with the Parkes radio telescope and its 13-beam receiver, casting some concern about the astrophysical nature of these signals. Here we present FRB 121102, the first FRB discovery from a geographic location other than Parkes. FRB 121102 was found in the Galactic anti-center region in the 1.4 GHz Pulsar Arecibo L-band Feed Array (ALFA) survey with the Arecibo Observatory with a DM = 557.4 ± 2.0 pc cm{sup –3}, pulse width of 3.0 ± 0.5 ms, and no evidence of interstellar scattering. The observed delay of the signal arrival time with frequency agrees precisely with the expectation of dispersion through an ionized medium. Despite its low Galactic latitude (b = –0.°2), the burst has three times the maximum Galactic DM expected along this particular line of sight, suggesting an extragalactic origin. A peculiar aspect of the signal is an inverted spectrum; we interpret this as a consequence of being detected in a sidelobe of the ALFA receiver. FRB 121102's brightness, duration, and the inferred event rate are all consistent with the properties of the previously detected Parkes bursts.

  10. Spectral Trends of Solar Bursts at Sub-THz Frequencies

    Science.gov (United States)

    Fernandes, L. O. T.; Kaufmann, P.; Correia, E.; Giménez de Castro, C. G.; Kudaka, A. S.; Marun, A.; Pereyra, P.; Raulin, J.-P.; Valio, A. B. M.

    2017-01-01

    Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 - 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 - 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena.

  11. Gamma-ray Bursts: a Probe of Black Holes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There is strong evidence for the existence of black holes (BHs) in someX-ray binaries and in most galactic nuclei based on different types of measurement,but black holes have not been definitely identified for the lack of very firm obser-vational evidence up to now. Because direct evidence for BHs should come fromdetermination of strong gravitational redshift, we expect an object can fall into theregion near the BH horizon where radiation can be detected. Therefore the ob-ject must be a compact star such as a neutron star (NS), and intense astrophysicalprocesses will release highly energetic radiation that is transient and fast-varying.These characteristics may point to the observed gamma-ray bursts (GRBs). Recentobservations of iron lines suggest that afterglows of GRBs show properties similarto those observed in active galactic nuclei (AGNs), implying that the GRBs mayoriginate from intense events related to black holes. A model for GRBs and after-glows is proposed here to obtain the range of gravitational redshifts (zg) of GRBswith known cosmological redshifts. Here, we provide a new method that, with asearch for high-energy emission lines (X- or γ-rays) in GRBs, one can determinethe gravitational redshift. We expect zg to be 0.5 or even larger, so we can ruleout the possibility of other compact objects such as NSs, and identify the centralprogenitors of GRBs as black holes.

  12. Can we detect, monitor, and characterize volcanic activity using 'off the shelf' webcams and low-light cameras?

    Science.gov (United States)

    Harrild, M.; Webley, P. W.; Dehn, J.

    2015-12-01

    The ability to detect and monitor precursory events, thermal signatures, and ongoing volcanic activity in near-realtime is an invaluable tool. Volcanic hazards often range from low level lava effusion to large explosive eruptions, easily capable of ejecting ash to aircraft cruise altitudes. Using ground based remote sensing to detect and monitor this activity is essential, but the required equipment is often expensive and difficult to maintain, which increases the risk to public safety and the likelihood of financial impact. Our investigation explores the use of 'off the shelf' cameras, ranging from computer webcams to low-light security cameras, to monitor volcanic incandescent activity in near-realtime. These cameras are ideal as they operate in the visible and near-infrared (NIR) portions of the electromagnetic spectrum, are relatively cheap to purchase, consume little power, are easily replaced, and can provide telemetered, near-realtime data. We focus on the early detection of volcanic activity, using automated scripts that capture streaming online webcam imagery and evaluate each image according to pixel brightness, in order to automatically detect and identify increases in potentially hazardous activity. The cameras used here range in price from 0 to 1,000 and the script is written in Python, an open source programming language, to reduce the overall cost to potential users and increase the accessibility of these tools, particularly in developing nations. In addition, by performing laboratory tests to determine the spectral response of these cameras, a direct comparison of collocated low-light and thermal infrared cameras has allowed approximate eruption temperatures to be correlated to pixel brightness. Data collected from several volcanoes; (1) Stromboli, Italy (2) Shiveluch, Russia (3) Fuego, Guatemala (4) Popcatépetl, México, along with campaign data from Stromboli (June, 2013), and laboratory tests are presented here.

  13. 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 ...

  14. Phase-locking of bursting neuronal firing to dominant LFP frequency components.

    Science.gov (United States)

    Constantinou, Maria; Elijah, Daniel H; Squirrell, Daniel; Gigg, John; Montemurro, Marcelo A

    2015-10-01

    Neuronal firing in the hippocampal formation relative to the phase of local field potentials (LFP) has a key role in memory processing and spatial navigation. Firing can be in either tonic or burst mode. Although bursting neurons are common in the hippocampal formation, the characteristics of their locking to LFP phase are not completely understood. We investigated phase-locking properties of bursting neurons using simulations generated by a dual compartmental model of a pyramidal neuron adapted to match the bursting activity in the subiculum of a rat. The model was driven with stochastic input signals containing a power spectral profile consistent with physiologically relevant frequencies observed in LFP. The single spikes and spike bursts fired by the model were locked to a preferred phase of the predominant frequency band where there was a peak in the power of the driving signal. Moreover, the preferred phase of locking shifted with increasing burst size, providing evidence that LFP phase can be encoded by burst size. We also provide initial support for the model results by analysing example data of spontaneous LFP and spiking activity recorded from the subiculum of a single urethane-anaesthetised rat. Subicular neurons fired single spikes, two-spike bursts and larger bursts that locked to a preferred phase of either dominant slow oscillations or theta rhythms within the LFP, according to the model prediction. Both power-modulated phase-locking and gradual shift in the preferred phase of locking as a function of burst size suggest that neurons can use bursts to encode timing information contained in LFP phase into a spike-count code.

  15. $\\gamma$-ray bursts as the birth-cries of black holes

    CERN Document Server

    Joshi, P; Maartens, R; Joshi, Pankaj; Dadhich, Naresh; Maartens, Roy

    2000-01-01

    The origin of cosmic gamma-ray bursts remains one of the most intriguing puzzles in astronomy. We suggest that purely general relativistic effects in the collapse of massive stars could account for these bursts. The late formation of closed trapped surfaces can occur naturally, allowing the escape of huge energy from curvature-generated fireballs, before these are hidden within a black hole.

  16. Synchrotron masers and fast radio bursts

    CERN Document Server

    Ghisellini, Gabriele

    2016-01-01

    Fast Radio Bursts (FRBs), with a typical duration of 1 ms and 1 Jy flux density at GHz frequencies, have brightness temperatures exceeding 1e33 K, requiring a coherent emission process. This can be achieved by bunching particles in volumes smaller than the typical wavelength, but this may be challenging. Alternatively, we can have maser emission. Under certain conditions, the synchrotron stimulated emission process can be more important than true absorption, and a synchrotron maser can be created. This occurs when the emitting electrons have a very narrow distribution of pitch angles and energies. This process overcomes the difficulties of having extremely dense bunches of particles and relaxes the light crossing time limits, since there is no simple relation between the actual size of the source and the observed variability timescale.

  17. On the three harmonics of solar type III bursts at the decameter wavelengths

    Science.gov (United States)

    Brazhenko, Anatolii; Pylaev, Oleg; Melnik, Valentin; Konovalenko, Alexandr; Zaqarashvili, Teimuraz; Rucker, Helmut; Frantsuzenko, Anatolii; Dorovskyy, Vladimir

    2014-05-01

    Harmonic structure of type III bursts are explained in terms of plasma emission mechanism. The second harmonic emission is well known. But there are theoretical papers about the third harmonic of type III bursts. And there were observations of the third harmonic of such types of bursts as U, J, V, II. We observed triple type III bursts where frequency ratio is close to 1:2:3. They are structures where type III emission is repeated at the double and triple frequencies. Incidentally, components of triple type III bursts are not only standard type III but also type IIIb bursts. We registered 30 triple bursts during 2011 and 2012 years. Observations were made by radio telescope URAN-2, Poltava, Ukraine. It enables polarization measurements at the frequencies 8 - 32 MHz. URAN-2 allows registration of radio emission with time and frequency resolution 10 ms and 4 kHz correspondingly. We analyze properties of the components of triple bursts and their dependencies on frequency, type of burst and on the position of the component within the triplet. The main properties of the components of triple bursts such as duration and drift rate are similar to those of standard type III and IIIb bursts. We find usual for type III bursts dependencies such as follow: duration decreases with frequency, the type IIIb bursts have always smaller duration at the same frequencies, all bursts drift from high to low frequencies. But we also find the linear dependence of drift rate on frequency. All components of a trio have the same sign of polarization. Polarization of the first component is always the highest in triple bursts. It corresponds to the generally accepted viewpoint about the first harmonic emission. The second and the third components of trio have low polarization. It is typical for the second and the third harmonics according to the plasma radiation mechanism. We discuss possible emission mechanisms and theoretical aspects of observed dependencies. The most of detected regularities

  18. 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.

  19. A Burst and Simultaneous Short-Term Pulsed Flux Enhancement From The Magnetar Candidate 1E 1048.1-5937

    Science.gov (United States)

    Gavriil, Fotis P.; Kaspi, Victoria M.; Woods, Peter M.

    2006-01-01

    We report on the 2004 June 29 X-ray burst detected from the direction of the AXP 1E 1048.1-5937 using the RXTE. We find a simultaneous increase of approx. 3.5 times the quiescent value in the 2-10 keV pulsed flux of 1E 1048.1-5937 during the tail of the burst, which identifies the AXP as the burst s origin. The burst was overall very similar to the two others reported from the direction of this source in 2001. The unambiguous identification of 1E 1048.1-5937 as the burster here confirms that it was the origin of the 2001 bursts as well. The epoch of the burst peak was very close to the arrival time of 1E 1048.1-5937 s pulse peak. The burst exhibited significant spectral evolution, with the trend going from hard to soft. Although the average spectrum of the burst was comparable in hardness (Lambda approx. 1.6) to those,of the 2001 bursts, the peak of this burst was much harder (Lambda approx. 0.3). During the 11 days following the burst, the AXP was observed further with RXTE, XMM-Newton, and Chandra. Pre- and post-burst observations revealed no change in the total flux or spectrum of the quiescent emission. Comparing all three bursts detected thus far from this source, we find that this event was the most fluent (>3.3 x 10(exp-8 ergs/sq cm) in the 2-20 keV band), had the highest peak flux (59+/-9 x 10(exp -10)ergs/s/sq cm) in the 2-20 keV band), and had the longest duration (>699 s). The long duration of the burst difFerentiates it from SGR bursts, which have typical durations of approx.0.1 s. Bursts that occur preferentially at pulse maximum, have fast rises, and long X-tails containing the majority of the total burst energy have been seen uniquely from AXPs. The marked differences between AXP and SGRs bursts may provide new clues to help understand the physical differences between these objects.

  20. Feasibility of a Small, Rapid Optical-to-IR Response, Next Generation Gamma Ray Burst Mission

    CERN Document Server

    Grossan, B; Bogomolov, V V; Svertilov, S I; Vedenkin, N N; Panasyuk, M; Goncharov, B; Rozhkov, G; Saleev, K; Grobovskoj, E; Krasnov, A S; Morozenko, V S; Osedlo, V I; Rogkov, E; Vachenko, T V; Linder, E V

    2013-01-01

    We present motivations for and study feasibility of a small, rapid optical to IR response gamma ray burst (GRB) space observatory. By analyzing existing GRB data, we give realistic detection rates for X-ray and optical/IR instruments of modest size under actual flight conditions. Given new capabilities of fast optical/IR response (about 1 s to target) and simultaneous multi-band imaging, such an observatory can have a reasonable event rate, likely leading to new science. Requiring a Swift-like orbit, duty cycle, and observing constraints, a Swift-BAT scaled down to 190 square cm of detector area would still detect and locate about 27 GRB per yr. for a trigger threshold of 6.5 sigma. About 23 percent of X-ray located GRB would be detected optically for a 10 cm diameter instrument (about 6 per yr. for the 6.5 sigma X-ray trigger).

  1. BRIGHT BROADBAND AFTERGLOWS OF GRAVITATIONAL WAVE BURSTS FROM MERGERS OF BINARY NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Gao He; Ding Xuan; Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Dai Zigao, E-mail: xfwu@pmo.ac.cn, E-mail: zhang@physics.unlv.edu, E-mail: dzg@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-07-10

    If double neutron star mergers leave behind a massive magnetar rather than a black hole, then a bright early afterglow can follow the gravitational wave burst (GWB) even if there is no short gamma-ray burst (SGRB)-GWB association or if there is an association but the SGRB does not beam toward Earth. Besides directly dissipating the proto-magnetar wind, as suggested by Zhang, here we suggest that the magnetar wind could push the ejecta launched during the merger process and, under certain conditions, would reach a relativistic speed. Such a magnetar-powered ejecta, when interacting with the ambient medium, would develop a bright broadband afterglow due to synchrotron radiation. We study this physical scenario in detail and present the predicted X-ray, optical, and radio light curves for a range of magnetar and ejecta parameters. We show that the X-ray and optical light curves usually peak around the magnetar spin-down timescale ({approx}10{sup 3}-10{sup 5} s), reaching brightnesses readily detectable by wide-field X-ray and optical telescopes, and remain detectable for an extended period. The radio afterglow peaks later, but is much brighter than the case without a magnetar energy injection. Therefore, such bright broadband afterglows, if detected and combined with GWBs in the future, would be a probe of massive millisecond magnetars and stiff equations of state for nuclear matter.

  2. Spectral Lags of Gamma-Ray Bursts From Ginga and BATSE

    CERN Document Server

    Wu, B; Wu, Bobing; Fenimore, Edward

    1999-01-01

    The analysis of spectral lag between energy bands, which combines temporal and spectral analyses, can add strict constraints to gamma-ray burst (GRB) models. In previous studies, the lag analysis focused on the lags between channel 1 (25-57 keV) and channel 3 (115-320 keV) from the Burst and Transient Source Experiment (BATSE). In this paper, we analyzed the cross-correlation average lags (including confidence regions) between energy bands for two GRB samples: 19 events detected by Ginga, and 109 bright events detected by BATSE. We paid special attention to the BATSE GRBs with known redshifts, because there has been a reported connection between lag and luminosity. The use of Ginga extends our knowledge of spectral lags to lower energy (~2 keV). We found that lags between energy bands are small. The lag between the peak of ~40 keV photons and ~200 keV photons is ~0.08 sec. The upper limit of the lag between shifts at low energy. We found that about 20% of GRBs have detectable lags between energy bands both fr...

  3. Application of Artificial Neural Network to Search for Gravitational-Wave Signals Associated with Short Gamma-Ray Bursts

    CERN Document Server

    Kim, Kyungmin; Hodge, Kari A; Kim, Young-Min; Lee, Chang-Hwan; Lee, Hyun Kyu; Oh, John J; Oh, Sang Hoon; Son, Edwin J

    2014-01-01

    We apply a machine learning algorithm, the artificial neural network, to the search for gravitational-wave signals associated with short gamma-ray bursts. The multi-dimensional samples consisting of data corresponding to the statistical and physical quantities from the coherent search pipeline are fed into the artificial neural network to distinguish simulated gravitational-wave signals from background noise artifacts. Our result shows that the data classification efficiency at a fixed false alarm probability is improved by the artificial neural network in comparison to the conventional detection statistic. Therefore, this algorithm increases the distance at which a gravitational-wave signal could be observed in coincidence with a gamma-ray burst. In order to demonstrate the performance, we also evaluate a few seconds of gravitational-wave data segment using the trained networks and obtain the false alarm probability. We suggest that the artificial neural network can be a complementary method to the conventio...

  4. Bursting Bubbles and Bilayers

    Directory of Open Access Journals (Sweden)

    Steven P. Wrenn, Stephen M. Dicker, Eleanor F. Small, Nily R. Dan, Michał Mleczko, Georg Schmitz, Peter A. Lewin

    2012-01-01

    Full Text Available This paper discusses various interactions between ultrasound, phospholipid monolayer-coated gas bubbles, phospholipid bilayer vesicles, and cells. The paper begins with a review of microbubble physics models, developed to describe microbubble dynamic behavior in the presence of ultrasound, and follows this with a discussion of how such models can be used to predict inertial cavitation profiles. Predicted sensitivities of inertial cavitation to changes in the values of membrane properties, including surface tension, surface dilatational viscosity, and area expansion modulus, indicate that area expansion modulus exerts the greatest relative influence on inertial cavitation. Accordingly, the theoretical dependence of area expansion modulus on chemical composition - in particular, poly (ethylene glyclol (PEG - is reviewed, and predictions of inertial cavitation for different PEG molecular weights and compositions are compared with experiment. Noteworthy is the predicted dependence, or lack thereof, of inertial cavitation on PEG molecular weight and mole fraction. Specifically, inertial cavitation is predicted to be independent of PEG molecular weight and mole fraction in the so-called mushroom regime. In the “brush” regime, however, inertial cavitation is predicted to increase with PEG mole fraction but to decrease (to the inverse 3/5 power with PEG molecular weight. While excellent agreement between experiment and theory can be achieved, it is shown that the calculated inertial cavitation profiles depend strongly on the criterion used to predict inertial cavitation. This is followed by a discussion of nesting microbubbles inside the aqueous core of microcapsules and how this significantly increases the inertial cavitation threshold. Nesting thus offers a means for avoiding unwanted inertial cavitation and cell death during imaging and other applications such as sonoporation. A review of putative sonoporation mechanisms is then presented

  5. Size of the top jet drop produced by bubble bursting

    CERN Document Server

    Ghabache, Elisabeth

    2016-01-01

    As a bubble bursts at a liquid-air interface, a tiny liquid jet rises and can release the so-called \\textit{jet drops}. In this paper, the size of the top jet drop produced by a bubble bursting is investigated experimentally. We determine, and discuss, the first scaling law enabling the determination of the top jet drop size as a function of the corresponding mother bubble radius and the liquid properties (viscosity, surface tension, density), along with its regime of existence. Furthermore, in the aim of decoupling experimentally the effects of bubble collapse and jet dynamics on the drop detachment, we propose a new scaling providing the top drop size only as a function of the jet velocity and liquid parameters. In particular, this allows us to untangle the intricate roles of viscosity, gravity and surface tension in the \\textit{end-pinching} of the bubble bursting jet.

  6. Temporal and spacial evolution of bursts in creep rupture.

    Science.gov (United States)

    Danku, Zsuzsa; Kun, Ferenc

    2013-08-23

    We investigate the temporal and spacial evolution of single bursts and their statistics emerging in heterogeneous materials under a constant external load. Based on a fiber bundle model we demonstrate that when the load redistribution is localized along a propagating crack front, the average temporal shape of pulses has a right-handed asymmetry; however, for long range interaction a symmetric shape with parabolic functional form is obtained. The pulse shape and spatial evolution of bursts proved to be correlated, which can be exploited in materials' testing. The probability distribution of the size and duration of bursts have power law behavior with a crossover to higher exponents as the load is lowered. The crossover emerges due to the competition of the slow and fast modes of local breaking being dominant at low and high loads, respectively.

  7. Numerical Simulations of Gamma-Ray Burst Explosions

    CERN Document Server

    Lazzati, Davide; López-Cámara, Diego

    2015-01-01

    Gamma-ray bursts are a complex, non-linear system that evolves very rapidly through stages of vastly different conditions. They evolve from scales of few hundred kilometers where they are very dense and hot to cold and tenuous on scales of parsecs. As such, our understanding of such a phenomenon can truly increase by combining theoretical and numerical studies adopting different numerical techniques to face different problems and deal with diverse conditions. In this review, we will describe the tremendous advancement in our comprehension of the bursts phenomenology through numerical modeling. Though we will discuss studies mainly based on jet dynamics across the progenitor star and the interstellar medium, we will also touch upon other problems such as the jet launching, its acceleration, and the radiation mechanisms. Finally, we will describe how combining numerical results with observations from Swift and other instruments resulted in true understanding of the bursts phenomenon and the challenges still lyi...

  8. A method to localize gamma-ray bursts using POLAR

    CERN Document Server

    Suarez-Garcia, E; Hajdas, W; Lamanna, G; Lechanoine-Leluc, C; Marcinkowski, R; Mtchedlishvili, A; Orsi, S; Pohl, M; Produit, N; Rapin, D; Rybka, D; Vialle, J -P; 10.1016/j.nima.2010.10.006

    2010-01-01

    The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50-500 keV photons arriving from the prompt emission of gamma-ray bursts (GRBs). The position in the sky of the detected GRBs is needed to determine their level of polarization. We present here a method by which, despite of the polarimeter incapability of taking images, GRBs can be roughly localized using POLAR alone. For this purpose scalers are attached to the output of the 25 multi-anode photomultipliers (MAPMs) that collect the light from the POLAR scintillator target. Each scaler measures how many GRB photons produce at least one energy deposition above 50 keV in the corresponding MAPM. Simulations show that the relative outputs of the 25 scalers depend on the GRB position. A database of very strong GRBs simulated at 10201 positions has been produced. When a GRB is detected, its location is calculated searching the minimum of the chi2 obtained in the comparison between the measured scaler pattern and the database. This GRB lo...

  9. Intensity distribution function and statistical properties of fast radio bursts

    Science.gov (United States)

    Li, Long-Biao; Huang, Yong-Feng; Zhang, Zhi-Bin; Li, Di; Li, Bing

    2017-01-01

    Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by millisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be , supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as , where is the observed radio fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.

  10. Varying Faces of Photospheric Emission in Gamma-Ray Bursts

    CERN Document Server

    Axelsson, M

    2015-01-01

    Among the more than 1000 gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope, a large fraction show narrow and hard spectra inconsistent with non-thermal emission, signifying optically thick emission from the photosphere. However, only a few of these bursts have spectra consistent with a pure Planck function. We will discuss the observational features of photospheric emission in these GRBs as well as in the ones showing multi-component spectra. We interpret the observations in light of models of subphotospheric dissipation, geometrical broadening and multi-zone emission, and show what we can learn about the dissipation mechanism and properties of GRB jets.

  11. New Canards Bursting and Canards Periodic-Chaotic Sequence

    Institute of Scientific and Technical Information of China (English)

    YOOER Chi-Feng; XU Jian-Xue; ZHANG Xin-Hua

    2009-01-01

    A trajectory following the repelling branch of an equilibrium or a periodic orbit is called a canards solution. Using a continuation method, we find a new type of canards bursting which manifests itself in an alternation between the oscillation phase following attracting the limit cycle branch and resting phase following a repelling fixed point branch in a reduced leech neuron model. Via periodic-chaotic alternating of infinite times, the number of windings within a canards bursting can approach infinity at a Gavrilov-Shilnikov homoclinic tangency bifurcation of a simple saddle limit cycle.

  12. Testing the Epeak - Eiso relation for GRBs detected by Swift and Suzaku-WAM

    CERN Document Server

    Krimm, H A; Sugita, S; Ohno, M; Sakamoto, T; Barthelmy, S D; Gehrels, N; Hara, R; Norris, J P; Ohmori, N; Onda, K; Sato, G; Tanaka, H; Tashiro, M; Yamauchi, M

    2009-01-01

    One of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy Epeak) of the nu-F(nu) spectrum and the isotropic radiated energy, Eiso. Since most gamma-ray bursts (GRBs) have Epeak above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate Epeak values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected, one can accurately fit Epeak and Eiso and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of April 2009, there were 48 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 48 bursts which triggered Swift and were detected by WAM, but did not trigger...

  13. Internal Luminosity Distribution of Bright Gamma-Ray Bursts and its Relation to Duration and Spectral Hardness

    Science.gov (United States)

    Horack, John M.; Hakkila, Jon

    1997-01-01

    We present first results from a comprehensive investigation into the distribution of luminosity within the 50 brightest cosmic gamma-ray bursts detected by the Burst and Transient Source Experiment (BATSE). The internal luminosity function psi(L) is defined such that the quantity psi(L)dL represents the fraction of total emission time during which the burst possesses a luminosity between L and L + dL. For these brightest bursts, the psi(L) functions are quasi-power-law-like and decrease in amplitude with increasing luminosity. Through investigation of both individual psi(L) distributions and data from the ensemble of bursts, we demonstrate a high probability for correlation between the shape of the internal luminosity function as measured by the average logarithmic slope and the burst duration as measured by the T(sub 90) parameter and, with lower significance, between the shape of psi(L) and the burst photon-fluence spectral index. We furthermore demonstrate a correlation between burst hardness ratio and duration in these brightest bursts which is opposite to that of the entire gamma-ray burst ensemble.

  14. Supernova detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakahata, Masayuki [Kamioka Observatory, Institute for Cosmic Ray research, University of Tokyo, Higashi-Mozumi, Kamioka-cho, Hida-shi, Gifu, Japan, 506-1205 (Japan)], E-mail: nakahata@suketto.icrr.u-tokyo.ac.jp

    2008-11-01

    The detection of supernova neutrinos is reviewed, focusing on the current status of experiments to detect supernova burst neutrinos and supernova relic neutrinos. The capabilities of each detector currently operating and in development are assessed and the likely neutrino yield for a future supernova is estimated. It is expected that much more information will be obtained if a supernova burst were to occur in our Galaxy than was obtained for supernova SN1987A. The detection of supernova relic neutrinos is considered and it is concluded that a large volume detector with a neutron tagging technique is necessary.

  15. Synchrotron masers and fast radio bursts

    Science.gov (United States)

    Ghisellini, G.

    2017-02-01

    Fast radio bursts, with a typical duration of 1 ms and 1 Jy flux density at gigahertz frequencies, have brightness temperatures exceeding 1033 K, requiring a coherent emission process. This can be achieved by bunching particles in volumes smaller than the typical wavelength, but this may be challenging. Maser emission is a possibility. Under certain conditions, the synchrotron-stimulated emission process can be more important than true absorption, and a synchrotron maser can be created. This occurs when the emitting electrons have a very narrow distribution of pitch angles and energies. This process overcomes the difficulties of having extremely dense bunches of particles and relaxes the light-crossing time limits, since there is no simple relation between the actual size of the source and the observed variability time-scale.

  16. VARIATION OF SPECTRAL AND TIMING PROPERTIES IN THE EXTENDED BURST TAILS FROM THE MAGNETAR 4U 0142+61

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Manoneeta; Göğüş, Ersin; Muş, Sinem Şaşmaz; Kaneko, Yuki, E-mail: manoneeta@sabanciuniv.edu [Sabancı University, Faculty of Engineering and Natural Sciences, Orhanlı Tuzla 34956, Istanbul (Turkey)

    2016-03-10

    Extended emission episodes with an intensity above the preburst level are observed following magnetar bursts from a number of soft gamma repeaters and anomalous X-ray pulsars (AXPs). Such extended tail emissions were observed following two events detected from AXP 4U 0142+61. We investigated in detail the evolution of spectral and temporal properties during these two tail segments using Rossi X-ray Timing Explorer/Proportional Counter Array observations, and report distinct variations in the spectral and temporal behavior throughout the tails. In particular, in both cases we observed a sudden enhancement of the pulsation amplitude in conjunction with bursts and a smooth decline of X-ray emission (cooling) during the tail. We suggest that an inefficiently radiating trapped fireball formed during the burst, which can heat up the stellar surface, is able to explain the tail properties and its energetics. We also present the episodic detection of absorption and emission features during tails. One possible mechanism that has been proposed to give rise to such spectral lines is the proton/ion cyclotron resonance process, which has been suggested as offering a valuable tool in probing the complex magnetic field of magnetars.

  17. Low-Resolution Spectroscopy of Gamma-ray Burst Optical Afterglows: Biases in the Swift Sample and Characterization of the Absorbers

    CERN Document Server

    Fynbo, J P U; Prochaska, J X; Malesani, D; Ledoux, C; Postigo, A de Ugarte; Nardini, M; Vreeswijk, P M; Hjorth, J; Sollerman, J; Chen, H -W; Thoene, C C; Bjoernsson, G; Bloom, J S; Castro-Tirado, A J; Christensen, L; De Cia, A; Gorosabel, J U; Jaunsen, A; Jensen, B L; Levan, A; Maund, J; Masetti, N; Milvang-Jensen, B; Palazzi, E; Perley, D A; Pian, E; Rol, E; Schady, P; Starling, R; Tanvir, N; Watson, D J; Wiersema, K; Xu, D; Augusteijn, T; Grundahl, F; Telting, J; Quirion, P -O

    2009-01-01

    (Abridged). We present a sample of 77 optical afterglows (OAs) of Swift detected GRBs for which spectroscopic follow-up observations have been secured. We provide linelists and equivalent widths for all detected lines redward of Ly-alpha. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray selected sample of Swift bursts with optimal conditions for ground-based follow up from the period March 2005 to September 2008; 146 bursts fulfill our sample criteria. We derive the redshift distribution for this sample and conclude that less than 19% of Swift bursts are at z>7. We compare the high energy properties for three sub-samples of bursts in the sample: i) bursts with redshifts measured from OA spectroscopy, ii) bursts with detected OA, but no OA-based redshift, and iii) bursts with no detection of the OA. The bursts in group i) have significantly less excess X-ray absorption than bursts in the other...

  18. Gamma-Ray Bursts: Should cosmologists care?

    Science.gov (United States)

    Laros, J. G.

    1996-03-01

    Gamma-Ray Burst (GRB) locations are distributed isotropically on the sky, but the intensity distribution of the bursts seems clearly incompatible with spatial homogeneity. Of the scenarios that attempt to provide an explanation, there are two that enjoy current popularity: (1) GRBs are produced by high-velocity neutron stars that have formed an extended (˜100 kpc) spherical halo or “corona” around our galaxy. (2) The bursters are at cosmological distances, with redshifts near unity for the weaker events. The major evidence used to argue for or against each of these scenarios remains inconclusive. Assuming, not unreasonably, that the cosmological scenario is correct, one can discuss the advantages and disadvantages of studying GRBs as opposed to other objects at moderate redshift. We find that the advantages of GRBs-high intensity, penetrating radiation, rapid variability, and no expected source evolution-are offset by observational difficulties pertaining to the extraction of cosmological information from GRB data. If the cosmological scenario proves to be correct and if the observational difficulties are overcome, then cosmologists certainly should care.

  19. Release from informational masking in children: Effect of multiple signal bursts

    Science.gov (United States)

    Leibold, Lori J.; Bonino, Angela Yarnell

    2009-01-01

    This study examined the degree to which increasing the number of signal presentations provides children with a release from informational masking. Listeners were younger children (5–7 years), older children (8–10 years), and adults. Detection thresholds were measured for a sequence of repeating 50-ms bursts of a 1000-Hz pure-tone signal embedded in a sequence of 10- and 50-ms bursts of a random-frequency, two-tone masker. Masker bursts were played at an overall level of 60-dB sound pressure level in each interval of a two-interval, forced choice adaptive procedure. Performance was examined for conditions with two, four, five, and six signal bursts. Regardless of the number of signal bursts, thresholds for most children were higher than thresholds for most adults. Despite developmental effects in informational masking, however, masked threshold decreased with additional signal bursts by a similar amount for younger children, older children, and adults. The magnitude of masking release for both groups of children and for adults was inconsistent with absolute energy