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Sample records for psr b1259-63 system

  1. Multifrequency Behaviour of the Gamma-Ray Binary System PSR B1259-63: Modelling the FERMI Flare

    Directory of Open Access Journals (Sweden)

    Brian van Soelen

    2014-12-01

    Full Text Available This paper presents a brief overview of the multifrequency properties of the gamma-ray binary system PSR B1259-63 from radio to very high energy gamma-rays. A summary is also presented of the various models put forward to explain the Fermi "flare" detected in 2011. Initial results are presented of a new turbulence driven model to explain the GeV observations.

  2. Recent Timing Results for PSR B1259 - 63

    Science.gov (United States)

    Wex, N.; Johnston, S.

    The binary pulsar PSR B1259 - 63 is in a highly eccentric 3.4 yr orbit around the Be star SS 2883. Timing observations of this pulsar, made over a 7 yr period using the Parkes 64 m radio-telescope, cover two periastron passages, in 1990 August and 1994 January. The timing observations of PSR B1259 - 63 clearly show evidence for timing noise which is domina ted by a cubic term. Unfortunately, the large amplitude timing noise and data over only two complete orbits make it difficult to produce a unique timing solution for this pulsar. However, if the long term behavior of timing noise is completely modeled by a cubic term, both dot ω and dot x terms are required in the timing model which could be a result of a precessing orbit caused by the quadrupole moment of the tilted companion star. In this paper we summarise the timing observations for the PSR B1259 - 63 system; full details are given in Wex et al. (1997).

  3. GAMMA-RAY SIGNAL FROM THE PULSAR WIND IN THE BINARY PULSAR SYSTEM PSR B1259-63/LS 2883

    Energy Technology Data Exchange (ETDEWEB)

    Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [National Research Nuclear University-MEPHI, Kashirskoe Shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d' Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

    2011-12-01

    Binary pulsar systems emit potentially detectable components of gamma-ray emission due to Comptonization of the optical radiation of the companion star by relativistic electrons of the pulsar wind, both before and after termination of the wind. The recent optical observations of binary pulsar system PSR B1259-63/LS 2883 revealed radiation properties of the companion star which differ significantly from previous measurements. In this paper, we study the implications of these observations for the interaction rate of the unshocked pulsar wind with the stellar photons and the related consequences for fluxes of high energy and very high energy (VHE) gamma rays. We show that the signal should be strong enough to be detected with Fermi close to the periastron passage, unless the pulsar wind is strongly anisotropic or the Lorentz factor of the wind is smaller than 10{sup 3} or larger than 10{sup 5}. The higher luminosity of the optical star also has two important implications: (1) attenuation of gamma rays due to photon-photon pair production and (2) Compton drag of the unshocked wind. While the first effect has an impact on the light curve of VHE gamma rays, the second effect may significantly decrease the energy available for particle acceleration after termination of the wind.

  4. Gamma–Gamma Absorption in the γ-ray Binary System PSR B1259-63/LS 2883

    Energy Technology Data Exchange (ETDEWEB)

    Sushch, Iurii [Centre for Space Research, North-West University, 2520 Potcheftroom (South Africa); Van Soelen, Brian, E-mail: iurii.sushch@desy.de, E-mail: vansoelenb@ufs.ac.za [Department of Physics, University of the Free State, 9300 Bloemfontein (South Africa)

    2017-03-10

    The observed TeV light curve from the γ -ray binary PSR B1259-63/LS 2883 shows a decrease in the flux at periastron that has not been fully explained by emission mechanisms alone. This observed decrease can, however, be explained by γγ absorption due to the stellar and disk photons. We calculate the γγ absorption in PSR B1259-63/LS 2883 taking into account photons from both the circumstellar disk and star, assuming that the γ -rays originate at the position of the pulsar. The γγ absorption due to the circumstellar disk photons produces a ≈14% decrease in the flux, and there is a total decrease of ≈52% (>1 TeV) within a few days before periastron, accompanied by a hardening of the γ -ray photon index. While the γγ absorption alone is not sufficient to explain the full complexity of the H.E.S.S. γ -ray light curve, it results in a significant decrease in the predicted flux, which is coincident with the observed decrease. In addition, we have calculated an upper limit on the γγ absorption, assuming that the emission is produced at the apex of the bow shock. Future observations with CTA during the 2021 periastron passage may be able to confine the location of the emission based on the degree of γγ absorption, as well as measure the hardening of the spectrum around periastron.

  5. The TeV {gamma}-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

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    Kerschhaggl, Matthias

    2010-04-06

    PSR B1259-63/SS2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a period of 3.4 years. The system exhibits variable, non-thermal radiation around periastron on the highly eccentric orbit (e=0.87) visible from radio to very high energies (VHE; E>100 GeV). When being detected in TeV {gamma}-rays with the High Energy Stereoscopic System (H.E.S.S.) in 2004 it became known as the first variable galactic VHE source. This thesis presents VHE data from PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Observations of VHE {gamma}-rays with the H.E.S.S. telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The H.E.S.S. instrument features an angular resolution of < 0.1 and an energy resolution of < 20%. Gamma-ray events in an energy range of 0.5-70 TeV were recorded. From these data, energy spectra and lightcurve with a monthly time sampling were extracted. VHE {gamma}-ray emission from PSRB1259-63 was detected with an overall significance of 9.5 standard deviations using 55 h of exposure, obtained from April to August 2007. The monthly flux of -rays during the observation period was measured, yielding VHE lightcurve data for the early pre-periastron phase of the system for the first time. No spectral variability was found on timescales of months. The spectrum is described by a power law with a photon index of {gamma}=2.8{+-}0.2{sub stat}{+-}0.2{sub sys} and flux normalisation {phi}{sub 0}=(1.1{+-}0.1{sub stat}{+-}0.2{sub sys}) x 10{sup -12} TeV{sup -1}cm{sup -2}s{sup -1}. PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of {gamma}-rays is seen in those observations. PSR B1259-63 has

  6. The TeV {gamma}-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

    Energy Technology Data Exchange (ETDEWEB)

    Kerschhaggl, Matthias

    2010-04-06

    PSR B1259-63/SS2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a period of 3.4 years. The system exhibits variable, non-thermal radiation around periastron on the highly eccentric orbit (e=0.87) visible from radio to very high energies (VHE; E>100 GeV). When being detected in TeV {gamma}-rays with the High Energy Stereoscopic System (H.E.S.S.) in 2004 it became known as the first variable galactic VHE source. This thesis presents VHE data from PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Observations of VHE {gamma}-rays with the H.E.S.S. telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The H.E.S.S. instrument features an angular resolution of < 0.1 and an energy resolution of < 20%. Gamma-ray events in an energy range of 0.5-70 TeV were recorded. From these data, energy spectra and lightcurve with a monthly time sampling were extracted. VHE {gamma}-ray emission from PSRB1259-63 was detected with an overall significance of 9.5 standard deviations using 55 h of exposure, obtained from April to August 2007. The monthly flux of -rays during the observation period was measured, yielding VHE lightcurve data for the early pre-periastron phase of the system for the first time. No spectral variability was found on timescales of months. The spectrum is described by a power law with a photon index of {gamma}=2.8{+-}0.2{sub stat}{+-}0.2{sub sys} and flux normalisation {phi}{sub 0}=(1.1{+-}0.1{sub stat}{+-}0.2{sub sys}) x 10{sup -12} TeV{sup -1}cm{sup -2}s{sup -1}. PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of {gamma}-rays is seen in those observations. PSR B1259-63 has

  7. The TeV γ-ray binary PSR B1259-63. Observations with the high energy stereoscopic system in the years 2005-2007

    International Nuclear Information System (INIS)

    Kerschhaggl, Matthias

    2010-01-01

    PSR B1259-63/SS2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a period of 3.4 years. The system exhibits variable, non-thermal radiation around periastron on the highly eccentric orbit (e=0.87) visible from radio to very high energies (VHE; E>100 GeV). When being detected in TeV γ-rays with the High Energy Stereoscopic System (H.E.S.S.) in 2004 it became known as the first variable galactic VHE source. This thesis presents VHE data from PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Observations of VHE γ-rays with the H.E.S.S. telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The H.E.S.S. instrument features an angular resolution of stat ±0.2 sys and flux normalisation Φ 0 =(1.1±0.1 stat ±0.2 sys ) x 10 -12 TeV -1 cm -2 s -1 . PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of γ-rays is seen in those observations. PSR B1259-63 has been re-confirmed as a variable TeV γ-ray emitter. The firm detection of VHE photons emitted at a true anomaly θ∼0.35 of the pulsar orbit, i.e. already ∝50 days prior to the periastron passage, disfavors the stellar disc target scenario as a primary emission mechanism, based on current knowledge about the companion star's disc inclination, extension, and density profile. In a phenomenological study indirect evidence that PSR B1259-63 could in fact be a periodical VHE emitter is presented using the TeV data discussed in this work. While the TeV energy flux level seems to be only dependent on the binary separation this behavior is not seen in X-rays. Moreover, model calculations based on inverse compton (IC) scattering of

  8. DISCOVERY OF HIGH-ENERGY GAMMA-RAY EMISSION FROM THE BINARY SYSTEM PSR B1259-63/LS 2883 AROUND PERIASTRON WITH FERMI

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bonamente, E.; Brigida, M.; Bruel, P.; Caliandro, G. A.

    2011-01-01

    We report on the discovery of ≥100 MeV γ-rays from the binary system PSR B1259-63/LS 2883 using the Large Area Telescope (LAT) on board Fermi. The system comprises a radio pulsar in orbit around a Be star. We report on LAT observations from near apastron to ∼128 days after the time of periastron, t p , on 2010 December 15. No γ-ray emission was detected from this source when it was far from periastron. Faint γ-ray emission appeared as the pulsar approached periastron. At ∼t p + 30 days, the ≥100 MeV γ-ray flux increased over a period of a few days to a peak flux 20-30 times that seen during the pre-periastron period, but with a softer spectrum. For the following month, it was seen to be variable on daily timescales, but remained at ∼(1-4) x 10 -6 cm -2 s -1 before starting to fade at ∼t p + 57 days. The total γ-ray luminosity observed during this period is comparable to the spin-down power of the pulsar. Simultaneous radio and X-ray observations of the source showed no corresponding dramatic changes in radio and X-ray flux between the pre-periastron and post-periastron flares. We discuss possible explanations for the observed γ-ray-only flaring of the source.

  9. On the timing behaviour of PSR B1259-63 under the propeller torque from a transient accretion disc

    Science.gov (United States)

    Yi, Shu-Xu; Cheng, K. S.

    2018-05-01

    The γ-ray pulsar binary system PSR B1259-63 flares in GeV after each periastron. The origin of these flares is still under debate. Recently, in 2017, we proposed a mechanism that might explain the GeV flares. In that model, a transient accretion disc is expected to be formed from the matter that was gravity-captured by the neutron star from the main-sequence companion's circumstellar disc. The transient accretion disc exerts a spin-down torque on the neutron star (i.e. the propeller effect), which might be traceable via pulsar timing observations of PSR B1259-63. In this paper, we consider the propeller effect phenomenologically using a parameter χ, which describes the coupling between the disc matter and the neutron star. Comparing the expected timing residuals with recent observations by Shannon et al., we conclude that the angular momentum transfer is very weak (with the coupling parameter χ ≤ 10-4).

  10. A New Approach to the GeV Flare of PSR B1259-63/LS2883

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Shu-Xu; Cheng, K. S., E-mail: yishuxu@hku.hk, E-mail: hrspksc@hku.hk [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2017-08-01

    PSR B1259-63/LS2883 is a binary system composed of a pulsar and a Be star. The Be star has an equatorial circumstellar disk (CD). The Fermi satellite discovered unexpected gamma-ray flares around 30 days after the last two periastron passages. The origin of the flares remains puzzling. In this work, we explore the possibility that the GeV flares are consequences of inverse Compton scattering of soft photons by the pulsar wind. The soft photons are from an accretion disk around the pulsar, which is composed of the matter from the CD captured by the pulsar’s gravity at disk-crossing before the periastron. At the other disk-crossing after the periastron, the density of the CD is not high enough, so accretion is prevented by the pulsar wind shock. This model can reproduce the observed spectrum energy distributions and light curves satisfactorily.

  11. ASTROPHYSICAL PARAMETERS OF LS 2883 AND IMPLICATIONS FOR THE PSR B1259-63 GAMMA-RAY BINARY

    International Nuclear Information System (INIS)

    Negueruela, Ignacio; Lorenzo, Javier; Ribo, Marc; Herrero, Artemio; Khangulyan, Dmitry; Aharonian, Felix A.

    2011-01-01

    Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input for understanding the physical mechanisms behind the particle acceleration, emission, and absorption processes in these so-called gamma-ray binaries. Here we present high-resolution and high signal-to-noise optical spectra of LS 2883, the Be star forming a gamma-ray binary with the young non-accreting pulsar PSR B1259-63, showing it to rotate faster and be significantly earlier and more luminous than previously thought. Analysis of the interstellar lines suggests that the system is located at the same distance as (and thus is likely a member of) Cen OB1. Taking the distance to the association, d = 2.3 kpc, and a color excess of E(B - V) = 0.85 for LS 2883 results in M V ∼ -4.4. Because of fast rotation, LS 2883 is oblate (R eq ≅ 9.7 R sun and R pole ≅ 8.1 R sun ) and presents a temperature gradient (T eq ∼ 27,500 K, log g eq = 3.7; T pole ∼ 34,000 K, log g pole = 4.1). If the star did not rotate, it would have parameters corresponding to a late O-type star. We estimate its luminosity at log(L * /L sun ) ≅ 4.79 and its mass at M * ∼ 30 M sun . The mass function then implies an inclination of the binary system i orb ∼ 23 0 , slightly smaller than previous estimates. We discuss the implications of these new astrophysical parameters of LS 2883 for the production of high-energy and very high-energy gamma rays in the PSR B1259-63/LS 2883 gamma-ray binary system. In particular, the stellar properties are very important for prediction of the line-like bulk Comptonization component from the unshocked ultrarelativistic pulsar wind.

  12. The 2017 Periastron Passage of PSR B1259-63 in Gamma-rays and X-rays

    Science.gov (United States)

    Wood, Kent S.; Johnson, Tyrel; Ray, Paul S.; Kerr, Matthew T.; Chernyakova, Masha; Fermi LAT Collaboration

    2018-01-01

    PSR B1259‑ 63 is a 48-ms radio pulsar in a highly eccentric 3.4-yr orbit with a Be star LS 2883. While the pulsed emission has been detected only in radio, un-pulsed radio, X-ray and gamma-ray emission are regularly observed from the binary system around the periastron. It is likely that the collision of the pulsar wind with the anisotropic wind of the Be star plays a crucial role in the generation of the observed non-thermal emission. The spectral energy distribution observed near periastron peaks in GeV gamma-rays, reaching maximum flux several weeks past periastron. In September 2017 it is being observed for a third periastron passage by the Fermi satellite. Here we present first results of the 2017 multi-wavelength campaign. The 2017 observations are compared to the two previous cycles, and used to test current models. Until recently there was no similar source known in the Galaxy but now a near-twin to it, PSR J2032+4127 , (Pspin=143 ms, Porbit ~50 yr, detectable radio to gamma rays) has been found, and is also undergoing periastron passage in Nov 2017. Gamma-ray and X-ray phenomena in the two sources are compared and discussed. These objects may represent a transitional phase, with possible later phases being accreting pulsars, and eventually perhaps NS-BH or NS-NS binary systems. Portions of this research performed at the US Naval Research Laboratory are sponsored by NASA DPR S-15633-Y.

  13. POST-PERIASTRON GAMMA-RAY FLARE FROM PSR B1259-63/LS 2883 AS A RESULT OF COMPTONIZATION OF THE COLD PULSAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [Department of Molecular Physics, National Research Nuclear University (MEPHI), Kashirskoe shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d' Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

    2012-06-10

    We argue that the bright flare of the binary pulsar PSR B1259-63/LS2883 detected by the Fermi Large Area Telescope is due to the inverse Compton scattering of the unshocked electron-positron pulsar wind with a Lorentz factor {Gamma}{sub 0} Almost-Equal-To 10{sup 4}. The combination of two effects both linked to the circumstellar disk (CD) is a key element in the proposed model. The first effect is related to the impact of the surrounding medium on the termination of the pulsar wind. Inside the disk, the 'early' termination of the wind results in suppression of its gamma-ray luminosity. When the pulsar escapes the disk, the conditions for termination of the wind undergo significant changes. This would lead to a dramatic increase of the pulsar wind zone, and thus to the proportional increase of the gamma-ray flux. On the other hand, if the parts of the CD disturbed by the pulsar can supply infrared photons of density high enough for efficient Comptonization of the wind, almost the entire kinetic energy of the pulsar wind would be converted to radiation, thus the gamma-ray luminosity of the wind could approach the level of the pulsar's spin-down luminosity as reported by the Fermi Collaboration.

  14. Modeling the emission of the galactic very high energy γ-ray sources G 1.9+0.3, G 330.2+1.0, HESS J1303-631 and PSR B1259-63/LS 2883 observed with H.E.S.S

    International Nuclear Information System (INIS)

    Sushch, Iurii

    2012-01-01

    Recently, imaging atmospheric Cherenkov telescopes (IACTs) have discovered numerous new sources representing various source classes in the very high energy (VHE; E>100 GeV) sky. This work presents studies of representatives of three types of Galactic VHE emitters: the Supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0, the pulsar wind nebula (PWN) HESS J1303.631 and the binary system PSR B1259.63/LS 2883. The analysis of the H.E.S.S. data and the broadband emission modeling are presented. G1.9+0.3 and G330.2+1.0 are synchrotron-dominated SNRs whose non-thermal X-ray emission implies that intensive particle acceleration occurs at their shock fronts. This makes them promising candidates for the detection at VHEs. They were observed by the High Energy Stereoscopic System (H.E.S.S.) yielding no signs of significant VHE γ-ray emission from either SNR. The 99% confidence level upper limits on the TeV flux were determined. For an assumed spectral index of 2.5 the obtained upper limits are F G1.9 (>260 GeV) -13 cm -2 s -1 for G1.9+0.3 and F G330 (>380 GeV) -12 cm -2 s -1 for G330.2+1.0. Upper limits on the VHE emission provide constraints on the interior magnetic field in the context of a leptonic scenario and on the interstellar medium (ISM) density and cosmic-ray (CR) efficiency in a hadronic scenario. Lower limits on the interior magnetic fields were estimated at 15 μG for G1.9+0.3 and 14 μG for G330.2+1.0. In the case of the hadronic scenario, the H.E.S.S. upper limits are two orders of magnitude greater than the flux prediction. Obtained upper limits on the ISM densities are compatible with other estimates of the densities (from the thermal X-ray emission for G330.2+1.0 and from the expansion rate for G1.9+0.3). The CR efficiency cannot be constrained with the current H.E.S.S. upper limits. HESS J1303-631 is an initially unidentified H.E.S.S. source which was recently identified as a PWN associated with the pulsar PSR J1301-6305. The broadband emission of the source

  15. Modeling the emission of the galactic very high energy {gamma}-ray sources G 1.9+0.3, G 330.2+1.0, HESS J1303-631 and PSR B1259-63/LS 2883 observed with H.E.S.S

    Energy Technology Data Exchange (ETDEWEB)

    Sushch, Iurii

    2012-10-19

    Recently, imaging atmospheric Cherenkov telescopes (IACTs) have discovered numerous new sources representing various source classes in the very high energy (VHE; E>100 GeV) sky. This work presents studies of representatives of three types of Galactic VHE emitters: the Supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0, the pulsar wind nebula (PWN) HESS J1303.631 and the binary system PSR B1259.63/LS 2883. The analysis of the H.E.S.S. data and the broadband emission modeling are presented. G1.9+0.3 and G330.2+1.0 are synchrotron-dominated SNRs whose non-thermal X-ray emission implies that intensive particle acceleration occurs at their shock fronts. This makes them promising candidates for the detection at VHEs. They were observed by the High Energy Stereoscopic System (H.E.S.S.) yielding no signs of significant VHE {gamma}-ray emission from either SNR. The 99% confidence level upper limits on the TeV flux were determined. For an assumed spectral index of 2.5 the obtained upper limits are F{sub G1.9}(>260 GeV)<4.6 x 10{sup -13} cm{sup -2}s{sup -1} for G1.9+0.3 and F{sub G330}(>380 GeV)<1.6 x 10{sup -12} cm{sup -2}s{sup -1} for G330.2+1.0. Upper limits on the VHE emission provide constraints on the interior magnetic field in the context of a leptonic scenario and on the interstellar medium (ISM) density and cosmic-ray (CR) efficiency in a hadronic scenario. Lower limits on the interior magnetic fields were estimated at 15 {mu}G for G1.9+0.3 and 14 {mu}G for G330.2+1.0. In the case of the hadronic scenario, the H.E.S.S. upper limits are two orders of magnitude greater than the flux prediction. Obtained upper limits on the ISM densities are compatible with other estimates of the densities (from the thermal X-ray emission for G330.2+1.0 and from the expansion rate for G1.9+0.3). The CR efficiency cannot be constrained with the current H.E.S.S. upper limits. HESS J1303-631 is an initially unidentified H.E.S.S. source which was recently identified as a PWN associated with

  16. More surprises from the violent gamma-ray binary LS 2883 /B1259-63.

    Science.gov (United States)

    Kargaltsev, Oleg; Hare, Jeremy; Pavlov, George G.

    2018-01-01

    We report the results of a Chandra X-ray Observatory (CXO) monitoring campaign of the high-mass gamma-ray binary LS 2883, which hosts the young pulsar B1259-63. The monitoring now covers two binary cycles (6.8 years) and allows us to conclude that ejections of high-velocity X-ray emitting material are common for this binary. In the first cycle we observed an extended feature which detached and moved away from the binary. The observed changes in position were consistent with a steady motion with v=(0.07+/-0.01)c and a slight hint of acceleration. Tracing the motion back in time suggested that the X-ray emitting matter was ejected close to periastron passage. In the last orbital cycle, accelerated motion (reaching (0.13+/-0.02)c) is strongly preferred over a steady motion (the latter would imply that the ejected material was launched ~400 days after the periastron passage). The moving feature is also more luminous, compared to the previous binary cycle, larger in its apparent extent, and exhibits a puzzling morphology. We will show the CXO movies from both binary cycles and discuss physical interpretation of the resolved outflow dynamics in this remarkable system, which provides unique insight into the properties of the pulsar and stellar winds and their interaction.

  17. PSR extraction kicker system improvements

    International Nuclear Information System (INIS)

    Hardek, T.W.

    1991-01-01

    A program to improve the reliability of hardware required to operate the Los Alamos Proton Storage Ring has been under way for the past three years. The extraction kicker system for the PSR was identified as one candidate for improvement. Pulse modulators produce 50kV pulses 360 nsec in length at up to 24-Hz pulse repetition rate and drive two 4-meter-long stripline electrodes. Sources of difficulty with this system included short width switch tube lifetime, drive cable electrical breakdown, high-voltage connector failure, and occasional electrode breakdown. This paper discusses modifications completed on this system to correct these difficulties. 2 refs., 3 figs

  18. PSR control system

    International Nuclear Information System (INIS)

    Clout, P.N.; Conley, A.P.; Bair, S.S.; Fuka, M.A.; Sandford, E.L.; Lander, R.F.; Wells, F.D.

    1985-01-01

    The control system for the Proton Storage Ring at Los Alamos has been essentially completed. Modifications are being applied that are required in the light of machine physics and operating experience. The present design of the system is described and future planned modifications are indicated

  19. Proton storage ring (PSR) diagnostics and control system

    International Nuclear Information System (INIS)

    Clout, P.

    1983-01-01

    When any new accelerator or storage ring is built that advances the state of the art, the diagnostic system becomes extremely important in tuning the facility to full specification. This paper will discuss the various diagnostic devices planned or under construction for the PSR and their connection into the control system

  20. Similarity of PSR J1906+0746 to PSR J0737–3039: a Candidate of a New Double Pulsar System?

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yi-Yan; Lingfu, Rong-Feng; Zhou, Zhu-Wen [School of Physics and Electronic Sciences, Guizhou Education University, Guiyang 550018 (China); Zhang, Cheng-Min; Li, Di [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Wang, De-Hua [School of Physics and Electronic Sciences, Guizhou Normal University, Guiyang 550001 (China); Pan, Yuan-Yue, E-mail: yangyiyan@gznc.edu.cn, E-mail: zhangcm@bao.ac.cn [Department of Physics, Xiangtan University, Xiangtan, 411105 (China)

    2017-02-01

    PSR J1906+0746 is a nonrecycled strong magnetic field neutron star (NS), sharing the properties of the secondary-formed NS PSR J0737–3039B in the double pulsar system PSR J0737–3039AB. By comparing the orbital parameters of PSR J1906+0746 with those of PSR J0737–3039AB, we conclude that both systems have a similar origin and evolution history, involving an e-capture process for forming the second-born NS, like in the case of PSR J0737–3039B. We expect the companion of PSR J1906+0746 to be a long-lived recycled pulsar with radio beams that currently cannot be observed from Earth. We suggest possible ways to detect its presence. To compare PSR J1906+0746 with PSR J0737–3039, we also present the mass distribution of eight pairs of double NSs and find that in double NSs the mass of the recycled pulsar is usually larger than that of the nonrecycled one, which may be the result of accretion.

  1. Los Alamos Proton Storage Ring (PSR) injection deflector system

    International Nuclear Information System (INIS)

    Jason, A.j.; Higgins, E.F.; Koelle, A.R.

    1983-01-01

    We describe a pulsed magnetic deflector system planned for the injection system of the PSR. Two sets of magnets, appropriately placed in the optical systems of both the ring and the injection transport line, provide control of the rate at which particles are injected into a given portion of transverse phase space and limit the interaction of stored beam with the injection stripping foil. High-current modulators that produce relatively complex waveforms are required for this purpose. Solid-state drivers using direct feedback to produce the necessary waveforms are discussed as replacements for the more conventional high-voltage tube technology

  2. New Acquisition System for the PSR Beam Pulse Charge Monitor

    International Nuclear Information System (INIS)

    Sellyey, William C.; Lewis, Paul S.

    2004-01-01

    A Pearson 1010 current monitor toroid has been in use for many years to measure the charge per bunch being delivered from the LANSCE Proton Storage Ring (PSR) to the Lujan Center's spallation neutron source. Improved electronics have been developed to process the toroid's signal. The new system generates a calibrated measurement of charge per pulse and is network-enabled to provide remote access to charge, current and other data via EPICS. It is experimentally demonstrated that accurate charge measurements can be made on calibration pulses that contain frequency components well above what is contained in a typical beam pulse. The new electronics consists of a National Instruments (NI) PXI-1002 chassis that contains a PXI-8176 controller, a PXI-5112 100-MS/s digitizer, and a PXI-6602 scalar and digital I/O module. The 8176 runs under the NI Real Time operating system and was programmed to integrate proton pulse waveforms acquired by the 5112 digitizer. For each beam pulse a 50-kHz pulse stream proportional to the pulse charge is generated by the 6602 and this real time information is distributed to all experimental areas

  3. Test of post-newtonian conservation laws in the binary system PSR 1913+16

    International Nuclear Information System (INIS)

    Will, C.M.

    1976-01-01

    Observations that set upper limits on secular changes in the pulsar period and orbital period in the binary system PSR 1913+16 may provide a test of post-Newtonian conservation laws. According to some metric theories of gravitation, the center of mass of a binary system may be accelerated in the direction of the periastron of the orbit because of a violation of post-Newtonian momentum conservation. In the binary system PSR 1913+16, this effect could produce secular changes in both pulsar and orbital periods (changing overall Doppler shift) as large as two parts in 10 6 per year. The size of the effect is proportional to the sine of the angle of periastron, to the difference in the masses of the components of the binary system, and to the combination of parametrized post-Newtonian parameters α 3 +zeta 2 -zeta/subw/. This combination is zero in any theory that predicts conserved total momentum for isolated systems (including general relativity and Brans-Dicke theory). Although solar-system experiments constrain α 3 and zeta/subw/ to be small, no decent direct limit has been placed on zeta 2 . Other possible sources of secular period changes in PSR 1913+16 are discussed and compared with this effect. It is also shown that a breakdown in the equality of active and passive gravitational masses (violation of ''Newton's third law'') leads only to periodic, unobservable orbital effects in a system like PSR 1913+16

  4. Fermi LAT Pulsed Detection of PSR J0737-3039A in the Double Pulsar System

    Science.gov (United States)

    Guillemot, L.; Kramer, M.; Johnson, T. J.; Craig, H. A.; Romani, R. W.; Venter, C.; Harding, A. K.; Ferdman, R. D.; Stairs, I. H.; Kerr, M.

    2013-01-01

    We report the Fermi Large Area Telescope discovery of gamma-ray pulsations from the 22.7 ms pulsar A in the double pulsar system J0737-3039A/B. This is the first mildly recycled millisecond pulsar (MSP) detected in the GeV domain. The 2.7 s companion object PSR J0737-3039B is not detected in gamma rays. PSR J0737-3039A is a faint gamma-ray emitter, so that its spectral properties are only weakly constrained; however, its measured efficiency is typical of other MSPs. The two peaks of the gamma-ray light curve are separated by roughly half a rotation and are well offset from the radio and X-ray emission, suggesting that the GeV radiation originates in a distinct part of the magnetosphere from the other types of emission. From the modeling of the radio and the gamma-ray emission profiles and the analysis of radio polarization data, we constrain the magnetic inclination alpha and the viewing angle zeta to be close to 90 deg., which is consistent with independent studies of the radio emission from PSR J0737-3039A. A small misalignment angle between the pulsar's spin axis and the system's orbital axis is therefore favored, supporting the hypothesis that pulsar B was formed in a nearly symmetric supernova explosion as has been discussed in the literature already.

  5. FERMI LAT PULSED DETECTION OF PSR J0737-3039A IN THE DOUBLE PULSAR SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Guillemot, L.; Kramer, M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Johnson, T. J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Craig, H. A.; Romani, R. W.; Kerr, M. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Venter, C. [Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, 2520 Potchefstroom (South Africa); Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ferdman, R. D. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, M13 9PL (United Kingdom); Stairs, I. H., E-mail: guillemo@mpifr-bonn.mpg.de [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada)

    2013-05-10

    We report the Fermi Large Area Telescope discovery of {gamma}-ray pulsations from the 22.7 ms pulsar A in the double pulsar system J0737-3039A/B. This is the first mildly recycled millisecond pulsar (MSP) detected in the GeV domain. The 2.7 s companion object PSR J0737-3039B is not detected in {gamma} rays. PSR J0737-3039A is a faint {gamma}-ray emitter, so that its spectral properties are only weakly constrained; however, its measured efficiency is typical of other MSPs. The two peaks of the {gamma}-ray light curve are separated by roughly half a rotation and are well offset from the radio and X-ray emission, suggesting that the GeV radiation originates in a distinct part of the magnetosphere from the other types of emission. From the modeling of the radio and the {gamma}-ray emission profiles and the analysis of radio polarization data, we constrain the magnetic inclination {alpha} and the viewing angle {zeta} to be close to 90 Degree-Sign , which is consistent with independent studies of the radio emission from PSR J0737-3039A. A small misalignment angle between the pulsar's spin axis and the system's orbital axis is therefore favored, supporting the hypothesis that pulsar B was formed in a nearly symmetric supernova explosion as has been discussed in the literature already.

  6. Spitzer MIPS Limits on Asteroidal Dust in the Pulsar Planetary System PSR B1257+12

    Science.gov (United States)

    Bryden, G.; Beichman, C. A.; Rieke, G. H.; Stansberry, J. A.; Stapelfeldt, K. R.; Trilling, D. E.; Turner, N. J.; Wolszczan, A.

    2006-01-01

    With the MIPS camera on Spitzer, we have searched for far-infrared emission from dust in the planetary system orbiting pulsar PSR B1257+12. With accuracies of 0.05 mJy at 24 microns and 1.5 mJy at 70 microns, photometric measurements find no evidence for emission at these wavelengths. These observations place new upper limits on the luminosity of dust with temperatures between 20 and 1000 K. They are particularly sensitive to dust temperatures of 100-200 K, for which they limit the dust luminosity to below 3 x 10(exp -5) of the pulsar's spin-down luminosity, 3 orders of magnitude better than previous limits. Despite these improved constraints on dust emission, an asteroid belt similar to the solar system's cannot be ruled out.

  7. High-energy Emissions from the Pulsar/Be Binary System PSR J2032+4127/MT91 213

    Energy Technology Data Exchange (ETDEWEB)

    Takata, J. [School of physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Tam, P. H. T. [Institute of Astronomy and Space Science, Sun Yat-Sen University, Guangzhou 510275 (China); Ng, C. W.; Cheng, K. S. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hui, C. Y., E-mail: takata@hust.edu.cn [Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2017-02-20

    PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25–50 years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR B1259–63/LS2883. It is expected therefore that PSR J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux from this system. In this paper, we also confirm a rapid increase in the X-ray flux along the orbit, while the GeV flux shows no significant change. We discuss the high-energy emissions from the shock caused by the pulsar wind and stellar wind interaction and examine the properties of the pulsar wind in this binary system. We argue that the rate of increase of the X-ray flux observed by Swift indicates (1) a variation of the momentum ratio of the two-wind interaction region along the orbit, or (2) an evolution of the magnetization parameter of the pulsar wind with the radial distance from the pulsar. We also discuss the pulsar wind/Be disk interaction at the periastron passage, and propose the possibility of formation of an accretion disk around the pulsar. We model high-energy emissions through the inverse-Compton scattering process of the cold-relativistic pulsar wind off soft photons from the accretion disk.

  8. On the origin of the system PSR B1757-24/SNR G5.4-1.2

    OpenAIRE

    Gvaramadze, V. V.

    2003-01-01

    A scenario for the origin of the system PSR B1757-24/supernova remnant (SNR) G5.4-1.2 is proposed. It is suggested that both objects are the remnants of a supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its evolution. This suggestion implies that (a) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble (i.e. from the centre of the future SNR), (b) ...

  9. On the origin of the system PSR B 1757-24/SNR G 5.4-1.2

    Science.gov (United States)

    Gvaramadze, V. V.

    2004-03-01

    A scenario for the origin of the system PSR B 1757-24/supernova remnant (SNR) G 5.4-1.2 is proposed. It is suggested that both objects are the remnants of a supernova (SN) that exploded within a pre-existing bubble blown-up by a runaway massive star (the SN progenitor) during the final (Wolf-Rayet) phase of its evolution. This suggestion implies that (a) the SN blast centre was significantly offset from the geometric centre of the wind-blown bubble (i.e. from the centre of the future SNR), (b) the bubble was surrounded by a massive wind-driven shell, and (c) the SN blast wave was drastically decelerated by the interaction with the shell. Therefore, one can understand how the relatively young and low-velocity pulsar PSR B 1757-24 was able to escape from the associated SNR G 5.4-1.2 and why the inferred vector of pulsar transverse velocity does not point away from the geometric centre of the SNR. A possible origin of the radio source G 5.27-0.9 (located between PSR B 1757-24 and the SNR G 5.4-1.2) is proposed. It is suggested that G 5.27-0.9 is a lobe of a low Mach number (≃1.7) jet of gas outflowing from the interior of G 5.4-1.2 through the hole bored in the SNR's shell by the escaping pulsar. It is also suggested that the non-thermal emission of the comet-shaped pulsar wind nebula originates in the vicinity of the termination shock and in the cylindric region of subsonically moving shocked pulsar wind. The role of magnetized wind-driven shells (swept-up during the Wolf-Rayet phase from the ambient interstellar medium with the regular magnetic field) in formation of elongated axisymmetric SNRs is discussed.

  10. High-energy gamma-ray emission in compact binaries

    International Nuclear Information System (INIS)

    Cerutti, Benoit

    2010-01-01

    Four gamma-ray sources have been associated with binary systems in our Galaxy: the micro-quasar Cygnus X-3 and the gamma-ray binaries LS I +61 degrees 303, LS 5039 and PSR B1259-63. These systems are composed of a massive companion star and a compact object of unknown nature, except in PSR B1259-63 where there is a young pulsar. I propose a comprehensive theoretical model for the high-energy gamma-ray emission and variability in gamma-ray emitting binaries. In this model, the high-energy radiation is produced by inverse Compton scattering of stellar photons on ultra-relativistic electron-positron pairs injected by a young pulsar in gamma-ray binaries and in a relativistic jet in micro-quasars. Considering anisotropic inverse Compton scattering, pair production and pair cascade emission, the TeV gamma-ray emission is well explained in LS 5039. Nevertheless, this model cannot account for the gamma-ray emission in LS I +61 degrees 303 and PSR B1259-63. Other processes should dominate in these complex systems. In Cygnus X-3, the gamma-ray radiation is convincingly reproduced by Doppler-boosted Compton emission of pairs in a relativistic jet. Gamma-ray binaries and micro-quasars provide a novel environment for the study of pulsar winds and relativistic jets at very small spatial scales. (author)

  11. VHE gamma-rays from radio pulsars and cataclysmic variables. [PSR 1055-52; PSR 1509-58; PSR 1620-26; PSR 1747-46; PSR 1800-21; PSR 1818-04; PSR 1821-24; PSR 1822-09; PSR 1823-13; PSR 1855+09; PSR 1929+10; PSR 1957+20

    Energy Technology Data Exchange (ETDEWEB)

    De Jager, O.C.; Brink, C.; Meintjies, P.J.; Nel, H.I.; North, A.R.; Raubenheimer, B.C.; Van der Walt, D.J. (Potchefstroom Univ. for C.H.E. (South Africa). Dept. of Physics)

    1990-03-01

    We present the results of observations (above 1 TeV) of radio pulsars and cataclysmic variables with the Potchefstroom air Cerenkov facility. We were able to confirm our previous detection of PSR 1509-58 and the final significance is 1.7x10{sup -5}. A DC enhancement at the 10{sup -3} significance level was seen from the L{sub 4} Lagrange position in the PSR 1957+20 system. This result was confirmed by COS-B data. We were also able to detect the 5.4 ms pulsar PSR 1855+09 at a marginal significance level of 5%. However, the best and longest observation indicates non-uniformity at the 0.005 significance level. The TeV light curve resembles the radio light curve. The latter is also reminiscent of other millisecond pulsar observed above 1 TeV. The intermediate polar AEAQR (P = 33.08s) shows a period shift which is consistent with recent model predictions. However, the present significance of this results does not allow an unambiguous claim. (orig.).

  12. Optical observations of the millisecond pulsars PSR 1937+214 and PSR 1953+29

    International Nuclear Information System (INIS)

    Loredo, T.J.; Ricker, G.R.; Rappaport, S.A.; Middleditch, J.

    1984-01-01

    The results of photometric and time-resolved optical observations of the fields of the recently discovered ultra-fast radio pulsars, PSR 1937+214 and PSR 1953+29 (Backer et al. 1982; Boriakoff et al. 1983) are reported. Deep images of the fields reveal no conspicuous optical counterpart for PSR 1937+214, though a star with m/sub r/ approx. 20.5 is coincident with the position of PSR 1953+29. Time-resolved images of the fields of both objects, obtained with a new stroboscopic technique, have yielded upper limits on the pulsed near-infrared emission from each object. Constraints on the physical models for these systems derived from the optical studies are briefly discussed. 25 references, 9 figures, 4 tables

  13. Status of the PSR improvement program

    International Nuclear Information System (INIS)

    Macek, R.J.; Fitzgerald, D.H.; Hoehn, M.V.; Ryder, R.D.; York, R.L.

    1993-01-01

    A program of improvements to increase intensity and improve reliability of the Los Alamos Proton Storage Ring (PSR) has been under way for several years. Reduction of stored beam loss rates by a factor of 4.6 since 1987 through exploitation of H 0 injection has allowed the average intensity to increase by a factor of two to 75μA. Reliability of the PSR and associated beam delivery systems has been improved by extensive rework of numerous subsystems. Radiation protection has been improved by additional shielding of Line D and extensive use of relatively fail-safe radiation detectors incorporated into an improved radiation security system

  14. High-Cadence Timing Observations of an Exoplanet-Pulsar System, PSR B1257+12

    Science.gov (United States)

    Rivera, Rudy; Wolszczan, Aleksander; Seymour, Andrew

    2016-01-01

    The pulsar B1257+12 was regularly observed and timed by Aleksander Wolszczan from its discovery in 1992 up to 2008. It is the first example of an exoplanet-pulsar system, and is modeled to consist of three planets. At the time, long term timing programs lacked the sensitivity to measure effects that low mass, short orbital period bodies would have on the pulse arrival times (TOA's) and its timing residuals. Newer technology, like the PUPPI backend at Arecibo, allows for the exploration of an untouched planet parameter space. The project consisted of conducting precise timing using PUPPI, taking two hour long observations at 327 MHz, 430 MHz, and L-Band Wide (LBW) frequencies for 25 days. The data is processed in order to obtain standard profiles and TOA's that would be introduced into TEMPO2, allowing data point manipulation by fitting them for known pulsar parameters to acquire post fit residuals with expected precisions below 1 μs. The observations yielded residuals ranging between 0.40 μs and 1.89 μs for 430 MHz and 327 MHz, while LBW resulted in values higher than 4.0 μs, which is attributed to the many radio frequency interference (RFI) bands present in the data. Combining the newly and previously acquired data revealed a decrease in the dispersion measure (DM), from 10.16550 pc/cm3 to 10.15325 pc/cm3, since the pulsar was last observed, which allowed a correction for the effects of interstellar scintillation, which are most noticed at 327 MHz.

  15. A histopathologic evaluation of the Plasma Skin Regeneration System (PSR) versus a standard carbon dioxide resurfacing laser in an animal model.

    Science.gov (United States)

    Fitzpatrick, R; Bernstein, E; Iyer, S; Brown, D; Andrews, P; Penny, K

    2008-02-01

    A variety of high energy, pulsed, and scanned carbon dioxide lasers are available to perform cutaneous resurfacing. Rhytec has developed a device for skin regeneration that utilizes energy delivered via a burst of nitrogen plasma. This study was undertaken to benchmark the energy outputs of the plasma skin regeneration device as compared to an ultra-short pulsed carbon dioxide laser (the control device). The two systems were compared for time to complete healing, and the healing response post-treatment. Three Yucatan mini-pigs were utilized for this study. Following anesthesia, five experimental sites were marked along the skin atop the psoas muscle on each side of the spine. Treatment was applied using either the plasma skin regeneration system or the carbon dioxide laser, with one site remaining untreated as a control. Biopsies were taken from all treatment sites 0, 2, 7, 14, 30, and 60 days following treatment and processed to hematoxylin-eosin staining. Histopathologic examination was performed by observers blinded as to the treatment conditions. Skin treated with the plasma skin regeneration device showed a wider range of tissue effects across the energy settings used as compared to the laser treatment. All treatment sites had clinically regenerated epidermis by 7 days after treatment, with active cellular response below the D/E junction noted at the day 30 time-point at energies ranging from 2 to 4 J. The Rhytec PSR system provides an attractive alternative to standard CO2 laser with good remodeling of tissue architecture. Epidermis regenerated after PSR treatment shows a smoother surface profile than adjacent untreated tissue.

  16. Secular dynamics of the triple system harboring PSR J0337+1715 and implications for the origin of its orbital configuration

    International Nuclear Information System (INIS)

    Rafikov, Roman R.

    2014-01-01

    We explore secular dynamics of a recently discovered hierarchical triple system consisting of the radio pulsar PSR J0337+1715 and two white dwarfs (WDs). We show that three-body interactions endow the inner binary with a large forced eccentricity and suppress its apsidal precession, to about 24% of the rate due to the general relativity. However, precession rate is still quite sensitive to the non-Newtonian effects and may be used to constrain gravity theories if measured accurately. A small value of the free eccentricity of the inner binary e i free ≈2.6×10 −5 and vanishing forced eccentricity of the outer, relatively eccentric binary naturally result in their apsidal near-alignment. In addition, this triple system provides a unique opportunity to explore excitation of both eccentricity and inclination in neutron star-WD binaries, e.g., due to random torques caused by convective eddies in the WD progenitor. We show this process to be highly anisotropic and more effective at driving eccentricity rather than inclination. The outer binary eccentricity and e i free exceed by more than an order of magnitude the predictions of the eccentricity-period relation of Phinney, which is not uncommon. We also argue that the non-zero mutual inclination of the two binaries emerges at the end of the Roche lobe overflow of the outer (rather than the inner) binary.

  17. Secular dynamics of the triple system harboring PSR J0337+1715 and implications for the origin of its orbital configuration

    Energy Technology Data Exchange (ETDEWEB)

    Rafikov, Roman R., E-mail: rrr@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08540 (United States)

    2014-10-10

    We explore secular dynamics of a recently discovered hierarchical triple system consisting of the radio pulsar PSR J0337+1715 and two white dwarfs (WDs). We show that three-body interactions endow the inner binary with a large forced eccentricity and suppress its apsidal precession, to about 24% of the rate due to the general relativity. However, precession rate is still quite sensitive to the non-Newtonian effects and may be used to constrain gravity theories if measured accurately. A small value of the free eccentricity of the inner binary e{sub i}{sup free}≈2.6×10{sup −5} and vanishing forced eccentricity of the outer, relatively eccentric binary naturally result in their apsidal near-alignment. In addition, this triple system provides a unique opportunity to explore excitation of both eccentricity and inclination in neutron star-WD binaries, e.g., due to random torques caused by convective eddies in the WD progenitor. We show this process to be highly anisotropic and more effective at driving eccentricity rather than inclination. The outer binary eccentricity and e{sub i}{sup free} exceed by more than an order of magnitude the predictions of the eccentricity-period relation of Phinney, which is not uncommon. We also argue that the non-zero mutual inclination of the two binaries emerges at the end of the Roche lobe overflow of the outer (rather than the inner) binary.

  18. Binary system containing the pulsar PSR 1913 + 16 and ultra-violet and x-radiation from accreting magnetic white dwarfs

    International Nuclear Information System (INIS)

    Masters, A.R.

    1978-01-01

    Part I of the thesis deals with the binary system containing the pulsar PSR 1913 + 16. The system has been touted as a laboratory for testing relativistic theories of gravity, and is also a challenge for theories of stellar evolution. However, proposed uses of the system rely on assumptions about the nature of the pulsar's unobserved companion. Ways of determining the nature of the companion from observation of the pulsar are discussed. Geometrical constraints on the size of the pulsar's orbit and the observed slow rate of the orbit's precession require that the companion be a black hole, a neutron star, a white dwarf or a helium main-sequence star. Observable second-order relativistic effects may or may not further restrict the list of candidates. The discussion summarizes Masters and Roberts, 1975 Ap.J. (Letters), 195, L107, and Roberts, Masters and Arnett, 1976, Ap. J., 203, 196. Part II of the thesis treats ultra-violet and X-radiation from accreting magnetic white dwarfs. Matter from a companion star falling onto a white dwarf is shock-heated near the stellar surface and radiatively cooled. The post-shock region is approximated by a uniform, geometrically thin slab and determine the physical conditions behind the shock and the emitted spectrum for a range of stellar masses, magnetic fields and accretion rates. At low magnetic fields and high accretion rates, bremsstrahlung is the dominant cooling mechanism and the post-shock material is a single fluid (the electrons and ions have a common temperature). As the magnetic field increases or the accretion rate decreases, cyclotron emission becomes more important than bremsstrahlung

  19. On the age of PSR B 1509-58

    Science.gov (United States)

    Gvaramadze, V. V.

    2001-07-01

    It is generally accepted that the PSR B 1509-58 is associated with the supernova remnant (SNR) MSH 15-52 (G 320.4-01.2). The spin-down age of the pulsar is =~ 1700 years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternative one and suggest that the high spin-down rate of the pulsar characterizes only a relatively short period of its (present) spin history, and that the enhanced braking torque is connected with the interaction between the pulsar's magnetosphere and the dense matter of a circumstellar clump (created during the late evolutionary stages of the supernova (SN) progenitor star). Our suggestion implies that the ``true" age of PSR B 1509-58 could be much larger than the spin-down age, and therefore the SNR MSH 15-52 is a middle-aged remnant similar to the Vela SNR (G 263.9-3.3). We also suggest that the dense (neutral) gas of the circumstellar clump could be responsible for the enhanced neutral hydrogen absorption towards PSR B 1509-58, and that the optical emission of an optical counterpart for PSR B 1509-58 should rather be attributed to a bow shock around this pulsar than to the pulsar itself.

  20. Optical counterparts of two Fermi millisecond pulsars: PSR J1301+0833 and PSR J1628–3205

    International Nuclear Information System (INIS)

    Li, Miao; Halpern, Jules P.; Thorstensen, John R.

    2014-01-01

    Using the 1.3 m and 2.4 m Telescopes of the MDM Observatory, we identified the close companions of two eclipsing millisecond radio pulsars that were discovered by the Green Bank Telescope in searches of Fermi Gamma-ray Space Telescope sources, and measured their light curves. PSR J1301+0833 is a black widow pulsar in a 6.5 hr orbit whose companion star is strongly heated on the side facing the pulsar. It varies from R = 21.8 to R > 24 around the orbit. PSR J1628–3205 is a 'redback', a nearly Roche-lobe-filling system in a 5.0 hr orbit whose optical modulation in the range 19.0 < R < 19.4 is dominated by strong ellipsoidal variations, indicating a large orbital inclination angle. PSR J1628–3205 also shows evidence for a long-term variation of about 0.2 mag, and an asymmetric temperature distribution possibly due to either off-center heating by the pulsar wind, or large starspots. Modeling of its light curve restricts the inclination angle to i > 55°, the mass of the companion to 0.16 < M c < 0.30 M ☉ , and the effective temperature to 3560 < T eff < 4670 K. As is the case for several redbacks, the companion of PSR J1628–3205 is less dense and hotter than a main-sequence star of the same mass.

  1. Study on the correlation of PSR with extended operation of NPP

    International Nuclear Information System (INIS)

    Shin, T. M.; Kim, H. K.; Cho, J. C.; Kim, H. J.

    2002-01-01

    For developed countries, which had already experienced the end of nuclear plant design life, it has been a trend to allow extended operation of plant in case that safety during the period of extended operation is ensured through safety assessment. Periodic Safety Review and License Renewal are the widely used system for safety assessment of extended operation. The PSR has been already adopted in our country and actively carried out one by one for each operating plant by the owner and its committed technical experts. In the paper, the interfaces between PSR and extended operation are reviewed in the regulatory viewpoint in recognition that various safety reviews are performed in PSR for the safety confirmation and enhancement, and that PSR can be effectively utilized for the review of extended operation. However, this study has been performed only on the research purpose and thus the final decision is up to the policy of government

  2. NuSTAR discovery of an unusually steady long-term spin-up of the Be binary 2RXP J130159.6-635806

    DEFF Research Database (Denmark)

    Krivonos, Roman A.; Tsygankov, Sergey S.; Lutovinov, Alexander A.

    2015-01-01

    We present spectral and timing analysis of NuSTAR observations of the accreting X-ray pulsar 2RXP J130159.6-635806. The source was serendipitously observed during a campaign focused on the gamma-ray binary PSR B1259-63 and was later targeted for a dedicated observation. The spectrum has a typical...

  3. UPPER LIMITS ON PULSED RADIO EMISSION FROM THE 6.85 s X-RAY PULSAR XTE J0103-728 IN THE SMALL MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    Crawford, Fronefield; Devour, Brian M.; Takacs, Brian P.; Lorimer, Duncan R.; Kondratiev, Vladislav I.

    2009-01-01

    X-ray pulsations with a 6.85 s period were recently detected in the Small Magellanic Cloud (SMC) and were subsequently identified as originating from the Be/X-ray binary system XTE J0103-728. The recent localization of the source of the X-ray emission has made a targeted search for radio pulsations from this source possible. The detection of pulsed radio emission from XTE J0103-728 would make it only the second system after PSR B1259-63 that is both a Be/X-ray binary and a radio pulsar. We observed XTE J0103-728 in 2008 February with the Parkes 64 m radio telescope soon after the identification of the source of X-ray pulsations was reported in order to search for corresponding radio pulsations. We used a continuous 6.4 hr observation with a 256 MHz bandwidth centered at 1390 MHz using the center beam of the Parkes multibeam receiver. In the subsequent data analysis, which included a folding search, a Fourier search, a fast-folding algorithm search, and a single pulse search, no pulsed signals were found for trial dispersion measures (DMs) between 0 and 800 pc cm -3 . This DM range easily encompasses the expected values for sources in the SMC. We place an upper limit of ∼45 mJy kpc 2 on the luminosity of periodic radio emission from XTE J0103-728 at the epoch of our observation, and we compare this limit to a range of luminosities measured for PSR B1259-63, the only Be/X-ray binary currently known to emit radio pulses. We also compare our limit to the radio luminosities of neutron stars having similarly long spin periods to XTE J0103-728. Since the radio pulses from PSR B1259-63 are eclipsed and undetectable during the portion of the orbit near periastron, repeated additional radio search observations of XTE J0103-728 may be valuable if it is undergoing similar eclipsing and if such observations are able to sample the orbital phase of this system well.

  4. On the age of PSR B1509-58

    OpenAIRE

    Gvaramadze, V. V.

    2001-01-01

    It is generally accepted that the PSR B1509-58 is associated with the supernova remnant (SNR) MSH 15-52 (G 320.4-01.2). The spin-down age of the pulsar is \\simeq 1700 years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternative one and suggest that the high spin-down rate of the pulsar characterizes only a relatively short period of its (present) spin history, ...

  5. Research on the maximum utilization of PSR (Periodic Safety Review) results

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Tae Myung; Lee, Jae Kyung; Ahn, Jin Chul; Kim, G. U.; Ryu, Y. S.; Lee, G. B.; Park, D. H. [Chungju Univ., Cheongju (Korea, Republic of)

    2002-03-15

    This is the final report of 'research on the maximum utilization of PSR results' focused on linkage strategy of PSR with continued operation over design life of operating NPP. Study was mace mainly on the analysis of current status of continued operation over plant design life in foreign countries, analysis of domestic PSR implementation status and establishment of basic strategy for linking PSR with continued operation. The results of the study performed so far can be summarized as below, the recent worldwide trend of promoting efficiency of NPP operation is focused on life extension of the plants rather than building of new. Considering the fact that some developed countries have already implemented the plant life extension and not a few countries at least have invested a good amount of fund for R and D of plant life management, we can not disregard the owner's request for review of life extension application without any reasonable description. As a result of investigation and analysis for the current status of continued operation over plant design life in foreign countries, it is concluded that most countries tend to link PSR with continued operation over plant design life and the extended operation has already been implemented in some developed countries. From the point, it turned out to be more desirable to couple those two systems for continued operation over plant design life of Korean NPP. A less than 7 years left until the end of design life for the oldest NPP Kori unit 1, it is strongly recommended to establish institutional frame including a legal basis and regulatory guidelines for continued operation over plant design life before long. For the prioritization methods of corrective actions in consideration of safety significance of shortcomings picked up from PSR, some related systems are reviewed including IAEA guidelines, PSR implementation experience of UK and US prioritization system for GSI (Generic Safety Issue). Basic principles are

  6. Are PSR 0656+14, PSR 0950+08, and PSR 1822-09 gamma ray pulsars?

    Science.gov (United States)

    Brown, Lawrence E.; Hartmann, Dieter H.

    1993-01-01

    The possible discovery of three new gamma-ray pulsars PSR 0656+14, PSR 0950+08, and PSR 1822-09 (Ma, Lu, Yu, and Young, 1993) in data obtained with the COS-B experiment is reinvestigated using a refined technique for pulsar light curve analysis. The results of this study do not confirm the previously claimed gamma-ray pulsar nature of any of these pulsars. Even when using the standard epoch folding technique in conjunction with energy-dependent acceptance cones, we do not detect pulsed gamma-ray emission from these sources. We suspect that insufficient position accuracy is the cause for the discrepancy between our results and those of Ma et al. (1993). We do not rule out that any one of the three candidates, or all of them, is in fact a gamma-ray pulsar, but their spin properties must differ from those derived by Ma et al. (1993). More work is needed to determine the correct high-energy properties of these three sources.

  7. CAMEX-3 POLARIMETRIC SCANNING RADIOMETER (PSR) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Polarimetric Scanning Radiometer (PSR) is a versatile airborne microwave imaging radiometer developed by the Georgia Institute of Technology and the NOAA...

  8. The Spin-down of PSR B1509-58

    Science.gov (United States)

    Gvaramadze, V. V.

    It is generally accepted that the PSR B1509-58 is associated with the supernova remnant (SNR) MSH 15-52 . The spin-down age of the pulsar is years, while the size and the general appearance of the SNR suggest that this system is much older. A few possible explanations of this discrepancy have been put forward. We offer an alternative one and suggest that the high spin-down rate of the pulsar characterizes only a relatively short period of its (present) spin history, and that the enhanced braking torque is connected with the interaction between the pulsar's magnetosphere and the dense matter of a circumstellar clump (created during the late evolutionary stages of the supernova (SN) progenitor star). Our suggestion implies that the "true" age of PSR B1509-58 could be much larger than the spin-down age, and therefore the SNR MSH 15-52 is a middle-aged remnant similar to the Vela SNR. Some possible consequences of our suggestion are discussed.

  9. What ionizes the interstellar hydrogen toward PSR 0950 + 08 and PSR 0823 + 26?

    International Nuclear Information System (INIS)

    Reynolds, R.J.

    1990-01-01

    Neither H II regions around nearby B stars nor known white dwarf stars can account for the free electron column densities along two well-defined line segments to the pulsars PSR 0950 + 08 and PSR 0823 + 26. The presence of the ionized gas seems to imply either (1) very long mean free path lengths for the absorption of Lyman continuum photons within the ISM (thereby suggesting a very different morphology for interstellar H I from that of the conventional view); or (2) Lyman continuum luminosities for early B or hot white dwarf stars that are more than an order of magnitude larger than currently accepted values; or (3) an additional and as yet unknown ionization source within the Galactic disk. 54 refs

  10. Study on the Correlation between PSR and Korean Stress Test for Continued Operation of Aging NPP

    International Nuclear Information System (INIS)

    Chung, June Ho; Kim, Tae Ryong

    2013-01-01

    Nuclear Safety and Security Commission (NSSC), Korean nuclear regulatory authority established the stress test guideline based on the EU stress test, and KHNP prepared the execution plan in response to the guideline for the CO of Kori Unit 1 and Wolsong Unit 1. PSR is a comprehensive safety review program for long term operation of NPP, which was developed by IAEA. Korea adopted PSR in 1999 as the regulatory requirement for CO of NPP. The IAEA standard guideline for PSR program was updated in 2003. However, the Korean PSR has not been revised yet to apply the new IAEA guidelines. Additionally, national legal systems and guidelines associated with the adoption of stress tests are urgently required as well. These revisions are imperative in order to ensure the reliability of NPPs, and to promote public acceptance and understanding. This study presents the technical basis and proposals for review actions necessary to address the issues and controversies surrounding the continued operation and decommissioning of aging NPPs in Korea. As discussed earlier in characteristics of Korean Stress Test, it is more comprehensive than the EU Stress Test in terms of its multilateral evaluation which includes equipment durability, plant operation, human factors, and safety margins, hence substantially raising the significance and value of the evaluation process. Thus, the addition of Korean Stress Test to the existing Korean Evaluation of CO is expected to greatly increase the quality of safety assessment of aging NPPs in Korea due to its stricter safety policies, hence providing a more meaningful evaluation process. However, a one-time application of the Korean Stress Test to only Kori Unit 1 and Wolsong Unit 1 would be a waste of the great effort that has been done thus far to improve the Korean Evaluation of CO and develop the Korean Stress Test. By extending the Korean Stress Test to all NPPs in Korea would maintain and ensure the reliability of NPPs as well as public

  11. PSR J1755-2550: a young radio pulsar with a massive, compact companion

    Science.gov (United States)

    Ng, C.; Kruckow, M. U.; Tauris, T. M.; Lyne, A. G.; Freire, P. C. C.; Ridolfi, A.; Caiazzo, I.; Heyl, J.; Kramer, M.; Cameron, A. D.; Champion, D. J.; Stappers, B.

    2018-06-01

    Radio pulsars found in binary systems with short orbital periods are usually fast spinning as a consequence of recycling via mass transfer from their companion stars; this process is also thought to decrease the magnetic field of the neutron star being recycled. Here, we report on timing observations of the recently discovered binary PSR J1755-2550 and find that this pulsar is an exception: with a characteristic age of 2.1 Myr, it is relatively young; furthermore, with a spin period of 315 ms and a surface magnetic field strength at its poles of 0.88 × 1012 G, the pulsar shows no sign of having been recycled. Based on its timing and orbital characteristics, the pulsar either has a massive white dwarf (WD) or a neutron star (NS) companion. To distinguish between these two cases, we searched radio observations for a potential recycled pulsar companion and analysed archival optical data for a potential WD companion. Neither work returned conclusive detections. We apply population synthesis modelling and find that both solutions are roughly equally probable. Our population synthesis also predicts a minimum mass of 0.90 M⊙ for the companion star to PSR J1755-2550 and we simulate the systemic runaway velocities for the resulting WDNS systems which may merge and possibly produce Ca-rich supernovae. Whether PSR J1755-2550 hosts a WD or a NS companion star, it is certainly a member of a rare subpopulation of binary radio pulsars.

  12. Confirmation of Earth-Mass Planets Orbiting the Millisecond Pulsar PSR B1257 + 12.

    Science.gov (United States)

    Wolszczan, A

    1994-04-22

    The discovery of two Earth-mass planets orbiting an old ( approximately 10(9) years), rapidly spinning neutron star, the 6.2-millisecond radio pulsar PSR B1257+12, was announced in early 1992. It was soon pointed out that the approximately 3:2 ratio of the planets' orbital periods should lead to accurately predictable and possibly measurable gravitational perturbations of their orbits. The unambiguous detection of this effect, after 3 years of systematic timing observations of PSR B1257+12 with the 305-meter Arecibo radiotelescope, as well as the discovery of another, moon-mass object in orbit around the pulsar, constitutes irrefutable evidence that the first planetary system around a star other than the sun has been identified.

  13. Discovery of remarkable subpulse drifting pattern in PSR B0818-41

    Science.gov (United States)

    Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M.

    The study of pulsars showing systematic subpulse drift patterns provides important clues for understanding of pulsar emission mechanism. Pulsars with wide profiles provide extra insights because of the presence of multiple drift bands (e.g PSR B0826-34). We report the discovery of a remarkable subpulse drift pattern in a relatively less studied wide profile pulsar, PSR B0818-41, using the GMRT. We find simultaneous occurrence of three drift regions with two drift rates, an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, the two closely spaced drift regions always maintain a constant phase relationship. These unique drift properties seen for this pulsar is very rare. We interpret that the observed drift pattern is created by intersection of our line of sight (LOS) with two conal rings in a inner LOS (negative beta) geometry. We argue that the carousel rotation periodicity (P_4) and the number of sparks (N_sp) are the same for the rings and claim that P_4 is close to the measured P_3. Based on our analysis results and interpretations, we simulate the radiation from B0818-41. The simulations support our interpretations and reproduce the average profile and the observed drift pattern. The results of our study show that PSR B0818-41 is a powerful system to explore the pulsar radio emission mechanism, the implications of which are also discussed in our work.

  14. THE EINSTEIN-HOME SEARCH FOR RADIO PULSARS AND PSR J2007+2722 DISCOVERY

    Energy Technology Data Exchange (ETDEWEB)

    Allen, B.; Knispel, B.; Aulbert, C.; Bock, O.; Eggenstein, H. B.; Fehrmann, H.; Machenschalk, B. [Max-Planck-Institut fuer Gravitationsphysik, D-30167 Hannover (Germany); Cordes, J. M.; Brazier, A.; Chatterjee, S. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Deneva, J. S. [Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612 (United States); Hessels, J. W. T. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Anderson, D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Demorest, P. B. [NRAO (National Radio Astronomy Observatory), Charlottesville, VA 22903 (United States); Gotthelf, E. V. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hammer, D. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Kaspi, V. M. [Department of Physics, McGill University, Montreal, QC H3A2T8 (Canada); Kramer, M. [Max-Planck-Institut fuer Radioastronomie, D-53121 Bonn (Germany); Lyne, A. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); McLaughlin, M. A., E-mail: bruce.allen@aei.mpg.de [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); and others

    2013-08-20

    Einstein-Home aggregates the computer power of hundreds of thousands of volunteers from 193 countries, to search for new neutron stars using data from electromagnetic and gravitational-wave detectors. This paper presents a detailed description of the search for new radio pulsars using Pulsar ALFA survey data from the Arecibo Observatory. The enormous computing power allows this search to cover a new region of parameter space; it can detect pulsars in binary systems with orbital periods as short as 11 minutes. We also describe the first Einstein-Home discovery, the 40.8 Hz isolated pulsar PSR J2007+2722, and provide a full timing model. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period. This neutron star is most likely a disrupted recycled pulsar, about as old as its characteristic spin-down age of 404 Myr. However, there is a small chance that it was born recently, with a low magnetic field. If so, upper limits on the X-ray flux suggest but cannot prove that PSR J2007+2722 is at least {approx}100 kyr old. In the future, we expect that the massive computing power provided by volunteers should enable many additional radio pulsar discoveries.

  15. Status of PSR [Proton Storage Ring

    International Nuclear Information System (INIS)

    Macek, R.J.

    1989-01-01

    The Los Alamos Proton Storage Ring (PSR) now operates with 35μA at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detailed studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 16 figs

  16. The binary nature of PSR J2032+4127

    International Nuclear Information System (INIS)

    Lyne, A. G.; Stappers, B. W.; Keith, M. J.; Ray, P. S.; Kerr, M.

    2015-01-01

    PSR J2032+4127 is a γ-ray and radio-emitting pulsar which has been regarded as a young luminous isolated neutron star. However, its recent spin-down rate has extraordinarily increased by a factor of 2. Here we present evidence that this is due to its motion as a member of a highly-eccentric binary system with an ~15–M⊙ Be star, MT91 213. Timing observations show that, not only are the positions of the two stars coincident within 0.4 arcsec, but timing models of binary motion of the pulsar fit the data much better than a model of a young isolated pulsar. MT91 213, and hence the pulsar, lie in the Cyg OB2 stellar association, which is at a distance of only 1.4–1.7 kpc. The pulsar is currently on the near side of, and accelerating towards, the Be star, with an orbital period of 20–30 yr. Finally, the next periastron is well constrained to occur in early 2018, providing an opportunity to observe enhanced high-energy emission as seen in other Be-star binary systems.

  17. The End of Accretion: The X-Ray Binary/Millisecond Pulsar Transition Object PSR J1023+0038

    Science.gov (United States)

    Archibald, Anne

    2015-04-01

    Millisecond radio pulsars (MSRPs), those spinning hundreds of times per second, have long been understood to be old pulsars that have been spun up by the accretion of matter from a companion in a low-mass X-ray binary (LMXB) phase. Yet the details of this transformation, particularly the end of the accretion process and the birth of a radio pulsar, remain mysterious. I will describe the discovery and detailed study of the first object known to transition between MSRP and LMXB states, PSR J1023+0038. By dint of a multiwavelength campaign of observations in the RMSP state, we are able to measure all the key system parameters and show the existence of an X-ray shock close to the pulsar-facing side of the companion. Since the discovery of PSR J1023+0038, two more objects (XSS J12270-4859 and M28I) have been found to make the same transition, and the study of these transitioning objects has become an active field of research. Most interestingly, PSR J1023+0038 has transitioned back into an LMXB state, with an active accretion disk and a puzzling increase in gamma-ray flux. Our detailed picture of the system allows us to test models of accretion against the phenomena we observe in PSR J1023+0038, and in fact these observations challenge current models: in spite of the low luminosity of the system (and low inferred accretion rate) some material is penetrating the centrifugal barrier and falling on the neutron-star surface. Key evidence for explaining this puzzling behaviour will come when PSR J1023+0038 returns to an MSRP state and we are able to compare pulsar timing models from after the LMXB state with those we obtained in this work.

  18. PSR B0826-34: SOMETIMES A ROTATING RADIO TRANSIENT

    International Nuclear Information System (INIS)

    Esamdin, A.; Niu, H. B.; Abdurixit, D.; Manchester, R. N.

    2012-01-01

    We report on the detection of sporadic, strong single pulses coexisting with a periodic weak emission in the duration of weak mode of PSR B0826–34. The intensities and durations of these pulses are comparable with those of the subpulses in the strong mode, and these pulses are distributed within the phase ranges of the main-pulse and interpulse of the strong-mode average profile. These results suggest that there is very possibly sporadic, very short timescale turn-on of strong-mode emission during the weak-mode state of the pulsar. The emission features of the bursts of strong pulses of PSR B0826–34 during its weak-mode state are similar to those of the rotating radio transients (RRATs). PSR B0826–34 is the second known pulsar, which oscillates between pulsar-like and RRAT-like modes.

  19. Ginga observations of the 50 millisecond pulsar PSR 0540 - 69

    International Nuclear Information System (INIS)

    Nagase, F.; Deeter, J.; Lewis, W.; Dotani, T.; Makino, F.

    1990-01-01

    Extensive Ginga observations of PSR 0540 - 69, the Crab-like 50-msec pulsar in the LMC, have been obtained as a side benefit of a pulsar search project for SN 1987A. Through a coherent pulse-timing analysis of data from 46 separate days between July 1987 and October 1988, precise values have been obtained for the pulse frequency and its first and second derivatives. From these values, a braking index of n = 2.02 + or = 0.01 is obtained for PSR 0540 - 69. This is the first accurate measurement of a pulsar braking index from X-ray observations and the third overall. The braking index is much smaller than those previously determined for the Crab pulsar (n = 2.51) and PSR 1509 - 58 (n = 2.83). 24 refs

  20. PSR J0751+1807: un ajuste a los parámetros característicos del sistema binario

    Science.gov (United States)

    De Vito, M. A.; Benvenuto, O. G.

    PSR J0751+1807 is a millisecond pulsar belonging to a binary system with a low mass white dwarf companion. This system belongs to the group of recycled pulsars by mass transfer from a close companion, accelerating the pulsar rotation in this process. The orbital period for the system is of 6 hours. In this work we show our fit to the characteristic parameters of the system presented by Nice et al. (2005) FULL TEXT IN SPANISH

  1. The Highly Relativistic Binary Pulsar PSR J0737-3039A: Discovery and Implications

    OpenAIRE

    Burgay, M.; D'Amico, N.; Possenti, A.; Manchester, R. N.; Lyne, A. G.; Joshi, B. C.; McLaughlin, M. A.; Kramer, M.; Sarkissian, J. M.; Camilo, F.; Kalogera, V.; Kim, C.; Lorimer, D. R.

    2004-01-01

    PSR J0737-3039A is a millisecond pulsar with a spin period of 22.7 ms included in a double-neutron star system with an orbital period of 2.4 hrs. Its companion has also been detected as a radio pulsar, making this binary the first known double-pulsar system. Its discovery has important implications for relativistic gravity tests, gravitational wave detection and plasma physics. Here we will shortly describe the discovery of the first pulsar in this unique system and present the first results ...

  2. Electron cloud diagnostics in use at the Los Alamos PSR

    International Nuclear Information System (INIS)

    Macek, R. J.; Browman, A.; Borden, M.; Fitzgerald, D.; Wang, T. S.; Zaugg, T.; Harkay, K.; Rosenberg, R.

    2003-01-01

    A variety of electron cloud diagnostics have been deployed at the Los Alamos Proton Storage Ring (PSR) to detect, measure, and characterize the electron cloud generated in this high intensity, long bunch accumulator ring. These include a version of the ANL-developed retarding field analyzers (RFA) augmented with LANL-developed electronics, a variant of the RFA denoted as the electron sweeping diagnostic (ESD), biased collection plates, and gas pulse measuring devices. The designs and experience with the performance and applicability to PSR are discussed

  3. SPECTROSCOPY OF THE INNER COMPANION OF THE PULSAR PSR J0337+1715

    International Nuclear Information System (INIS)

    Kaplan, David L.; Van Kerkwijk, Marten H.; Koester, Detlev; Stairs, Ingrid H.; Ransom, Scott M.; Archibald, Anne M.; Hessels, Jason W. T.; Boyles, Jason

    2014-01-01

    The hierarchical triple system PSR J0337+1715 offers an unprecedented laboratory to study secular evolution of interacting systems and to explore the complicated mass-transfer history that forms millisecond pulsars and helium-core white dwarfs. The latter in particular, however, requires knowledge of the properties of the individual components of the system. Here we present precise optical spectroscopy of the inner companion in the PSR J0337+1715 system. We confirm it as a hot, low-gravity DA white dwarf with T eff = 15, 800 ± 100 K and log 10 (g) = 5.82 ± 0.05. We also measure an inner mass ratio of 0.1364 ± 0.0015, entirely consistent with that inferred from pulsar timing, and a systemic radial velocity of 29.7 ± 0.3 km s –1 . Combined with the mass (0.19751 M ☉ ) determined from pulsar timing, our measurement of the surface gravity implies a radius of 0.091 ± 0.005 R ☉ ; combined further with the effective temperature and extinction, the photometry implies a distance of 1300 ± 80 pc. The high temperature of the companion is somewhat puzzling: with current models, it likely requires a recent period of unstable hydrogen burning, and suggests a surprisingly short lifetime for objects at this phase in their evolution. We discuss the implications of these measurements in the context of understanding the PSR J0337+1715 system, as well as of low-mass white dwarfs in general

  4. The spin histories of PSR1821-24 in M28 and PSR1951+32 in CTB80

    International Nuclear Information System (INIS)

    White, N.E.; Stella, L.

    1988-01-01

    The spin histories of the 3.05-ms pulsar PSR 1821-24 in the globular cluster M28 and the pulsar PSR 1951 + 32 in the supernova remnant C + B80, show that the equation for the minimum possible period for the spin-up by accretion of an accreting magnetized neutron star is not correct. Also the equation should not be considered a 'hard' barrier when considering the magnetic field-period distribution of recycled radio pulsars. The rapid rotation period and period derivative of both pulsars are consistent with both having undergone a previous interval of accretion. (U.K.)

  5. SSR: What's in "School Science Review" for "PSR" Readers?

    Science.gov (United States)

    Lakin, Liz

    2004-01-01

    This article summarises ideas and developments in teaching and learning in science of relevance to "Primary Science Review" ("PSR") readers from three recent issues (309, 310, and 311) of "School Science Review" ("SSR"), the ASE journal for science education 11-19. The themes running through these are: ICT, the implications for science education…

  6. Improved timing of the millisecond pulsar PSR 1937+21 using real-time coherent dedispersion

    International Nuclear Information System (INIS)

    Hankins, T.H.; Stinebring, D.R.; Rawley, L.A.; Princeton Univ., NJ)

    1987-01-01

    Profiles of the millisecond pulsar PSR 1937+21 have been obtained with 6-micron resolution using a real-time hardware dispersion removal device. This dedisperser has a potential resolution of better than 0.5 microsec and is immune to time-of-arrival jitter caused by scintillation-induced spectral gradients across the receiver passband. It significantly reduces the time-of-arrival residuals when compared with the timing technique currently in use. This increased timing accuracy, when utilized in a long-term timing program of millisec pulsars, will improve the solar system ephemeris and will substantially improve the detection limit of a gravitational wave background. 27 references

  7. DISCOVERY OF GAMMA-RAY PULSATIONS FROM THE TRANSITIONAL REDBACK PSR J1227-4853

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J. [College of Science, George Mason University, Fairfax, VA 22030 (United States); Ray, P. S.; Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Roy, J.; Bhattacharyya, B.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pletsch, H. J.; Fort, S. [Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover (Germany); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Deneva, J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Kerr, M., E-mail: tyrel.j.johnson@gmail.com, E-mail: Paul.Ray@nrl.navy.mil, E-mail: jayanta.roy@manchester.ac.uk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping NSW 1710 (Australia)

    2015-06-10

    The 1.69 ms spin period of PSR J1227−4853 was recently discovered in radio observations of the low-mass X-ray binary XSS J12270−4859 following the announcement of a possible transition to a rotation-powered millisecond pulsar state, inferred from decreases in optical, X-ray, and gamma-ray flux from the source. We report the detection of significant (5σ) gamma-ray pulsations after the transition, at the known spin period, using ∼1 year of data from the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray light curve of PSR J1227−4853 can be fit by one broad peak, which occurs at nearly the same phase as the main peak in the 1.4 GHz radio profile. The partial alignment of light-curve peaks in different wavebands suggests that at least some of the radio emission may originate at high altitude in the pulsar magnetosphere, in extended regions co-located with the gamma-ray emission site. We folded the LAT data at the orbital period, both pre- and post-transition, but find no evidence for significant modulation of the gamma-ray flux. Analysis of the gamma-ray flux over the mission suggests an approximate transition time of 2012 November 30. Continued study of the pulsed emission and monitoring of PSR J1227−4853, and other known redback systems, for subsequent flux changes will increase our knowledge of the pulsar emission mechanism and transitioning systems.

  8. PSR experience with beam losses, instabilities and space charge effects

    International Nuclear Information System (INIS)

    Macek, R.J.

    1998-01-01

    Average current from the PSR has been limited to ∼70 μA at 20 Hz by beam losses of 0.4 to 0.5 μA which arise from two principal causes, production of H 0 excited states and stored-beam scattering in the stripper foil. To reduce beam losses, an upgrade from the two-step H 0 injection to direct H - injection is underway and will be completed in 1998. Peak intensity from the PSR is limited by a strong instability that available evidence indicates is the two-stream e-p instability. New evidence for the e-p hypothesis is presented. At operating intensities, the incoherent space charge tune shift depresses both horizontal and vertical tunes past the integer without additional beam loss although some intensity-dependent emittance growth is observed. copyright 1998 American Institute of Physics

  9. PSR experience with beam losses, instabilities and space charge effects

    International Nuclear Information System (INIS)

    Macek, Robert J.

    1998-01-01

    Average current from the PSR has been limited to ∼70 μA at 20 Hz by beam losses of 0.4 to 0.5 μA which arise from two principal causes, production of H 0 excited states and stored-beam scattering in the stripper foil. To reduce beam losses, an upgrade from the two-step H 0 injection to direct H - injection is underway and will be completed in 1998. Peak intensity from the PSR is limited by a strong instability that available evidence indicates is the two-stream e-p instability. New evidence for the e-p hypothesis is presented. At operating intensities, the incoherent space charge tune shift depresses both horizontal and vertical tunes past the integer without additional beam loss although some intensity-dependent emittance growth is observed

  10. Electron-cloud simulation results for the PSR and SNS

    International Nuclear Information System (INIS)

    Pivi, M.; Furman, M.A.

    2002-01-01

    We present recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos. In particular, a complete refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has been included in the simulation code

  11. Future directions in controlling the LAMPF-PSR Accelerator Complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Stuewe, R.; Schaller, S.; Bjorklund, E.; Burns, M.; Callaway, T.; Carr, G.; Cohen, S.; Kubicek, D.; Harrington, M.; Poore, R.; Schultz, D.

    1991-01-01

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-sever model-based data acquisition and control system. An increased use of the distributed intelligence at both the front-end and operator interface is a key element of the projects. 2 refs., 2 figs

  12. Future directions in controlling the LAMPF-PSR accelerator complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Stuewe, R.; Schaller, S.; Bjorklund, E.

    1992-01-01

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-server model-based data acquisition and control system. An increased use of distributed intelligence at both the front-end and the operator interface is a key element of the projects. (author)

  13. PSR J1740-3052: a pulsar with a massive companion

    Science.gov (United States)

    Stairs, I. H.; Manchester, R. N.; Lyne, A. G.; Kaspi, V. M.; Camilo, F.; Bell, J. F.; D'Amico, N.; Kramer, M.; Crawford, F.; Morris, D. J.; Possenti, A.; McKay, N. P. F.; Lumsden, S. L.; Tacconi-Garman, L. E.; Cannon, R. D.; Hambly, N. C.; Wood, P. R.

    2001-08-01

    We report on the discovery of a binary pulsar, PSR J1740-3052, during the Parkes multibeam survey. Timing observations of the 570-ms pulsar at Jodrell Bank and Parkes show that it is young, with a characteristic age of 350kyr, and is in a 231-d, highly eccentric orbit with a companion whose mass exceeds 11Msolar. An accurate position for the pulsar was obtained using the Australia Telescope Compact Array. Near-infrared 2.2-μm observations made with the telescopes at the Siding Spring observatory reveal a late-type star coincident with the pulsar position. However, we do not believe that this star is the companion of the pulsar, because a typical star of this spectral type and required mass would extend beyond the orbit of the pulsar. Furthermore, the measured advance of periastron of the pulsar suggests a more compact companion, for example, a main-sequence star with radius only a few times that of the Sun. Such a companion is also more consistent with the small dispersion measure variations seen near periastron. Although we cannot conclusively rule out a black hole companion, we believe that the companion is probably an early B star, making the system similar to the binary PSR J0045-7319.

  14. DISCOVERY OF GAMMA-RAY ORBITAL MODULATION IN THE BLACK WIDOW PSR J1311–3430

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yi; Wang, Zhongxiang [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2015-05-10

    We report our discovery of orbitally modulated γ-ray emission from the black widow system PSR J1311−3430. We analyze the Fermi Large Area Telescope data during the off-pulse phase interval of the pulsar and find the orbital modulation signal at a ∼3σ confidence level. Further spectral analysis shows no significant differences for the spectra obtained during the bright and faint orbital phase ranges. A simple sinusoid-like function can describe the modulation. Given these properties, we suggest that the intrabinary γ-ray emission arises from the region close to the companion and the modulation is caused by the occultation of the emitting region by the companion, similar to that is seen in the transitional millisecond pulsar binary (MSP) PSR J1023+0038. Considering the X-ray detection of intrabinary shock emission from eclipsing MSP binaries recently reported, this discovery further suggests the general existence of intrabinary γ-ray emission from them.

  15. PSR J1838–0537: DISCOVERY OF A YOUNG, ENERGETIC GAMMA-RAY PULSAR

    International Nuclear Information System (INIS)

    Pletsch, H. J.; Allen, B.; Aulbert, C.; Fehrmann, H.; Guillemot, L.; Kramer, M.; Baring, M. G.; Camilo, F.; Caraveo, P. A.; Marelli, M.; Grove, J. E.; Ray, P. S.; Kerr, M.; Ransom, S. M.; Saz Parkinson, P. M.

    2012-01-01

    We report the discovery of PSR J1838–0537, a gamma-ray pulsar found through a blind search of data from the Fermi Large Area Telescope (LAT). The pulsar has a spin frequency of 6.9 Hz and a frequency derivative of –2.2 × 10 –11 Hz s –1 , implying a young characteristic age of 4970 yr and a large spin-down power of 5.9 × 10 36 erg s –1 . Follow-up observations with radio telescopes detected no pulsations; thus PSR J1838–0537 appears radio-quiet as viewed from Earth. In 2009 September the pulsar suffered the largest glitch so far seen in any gamma-ray-only pulsar, causing a relative increase in spin frequency of about 5.5 × 10 –6 . After the glitch, during a putative recovery period, the timing analysis is complicated by the sparsity of the LAT photon data, the weakness of the pulsations, and the reduction in average exposure from a coincidental, contemporaneous change in LAT's sky-survey observing pattern. The pulsar's sky position is coincident with the spatially extended TeV source HESS J1841–055 detected by the High Energy Stereoscopic System (H.E.S.S.). The inferred energetics suggest that HESS J1841–055 contains a pulsar wind nebula powered by the pulsar.

  16. Psr is involved in regulation of glucan production, and double deficiency of BrpA and Psr is lethal in Streptococcus mutans.

    Science.gov (United States)

    Bitoun, Jacob P; Liao, Sumei; McKey, Briggs A; Yao, Xin; Fan, Yuwei; Abranches, Jacqueline; Beatty, Wandy L; Wen, Zezhang T

    2013-03-01

    Streptococcus mutans, the primary causative agent of dental caries, contains two paralogues of the LytR-CpsA-Psr family proteins encoded by brpA and psr, respectively. Previous studies have shown that BrpA plays an important role in cell envelope biogenesis/homeostasis and affects stress responses and biofilm formation by Strep. mutans, traits critical to cariogenicity of this bacterium. In this study, a Psr-deficient mutant, TW251, was constructed. Characterization of TW251 showed that deficiency of Psr did not have any major impact on growth rate. However, when subjected to acid killing at pH 2.8, the survival rate of TW251 was decreased dramatically compared with the parent strain UA159. In addition, TW251 also displayed major defects in biofilm formation, especially during growth with sucrose. When compared to UA159, the biofilms of TW251 were mainly planar and devoid of extracellular glucans. Real-time-PCR and Western blot analyses revealed that deficiency of Psr significantly decreased the expression of glucosyltransferase C, a protein known to play a major role in biofilm formation by Strep. mutans. Transmission electron microscopy analysis showed that deficiency of BrpA caused alterations in cell envelope and cell division, and the most significant defects were observed in TW314, a Psr-deficient and BrpA-down mutant. No such effects were observed with Psr mutant TW251 under similar conditions. These results suggest that while there are similarities in functions between BrpA and Psr, distinctive differences also exist between these two paralogues. Like Bacillus subtilis but different from Staphylococcus aureus, a functional BrpA or Psr is required for viability in Strep. mutans.

  17. DISCOVERY OF PSR J1227−4853: A TRANSITION FROM A LOW-MASS X-RAY BINARY TO A REDBACK MILLISECOND PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Jayanta; Bhattacharyya, Bhaswati; Stappers, Ben [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, M13 9PL (United Kingdom); Ray, Paul S.; Wolff, Michael; Wood, Kent S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Chengalur, Jayaram N. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Deneva, Julia [NRC Research Associate, resident at Naval Research Laboratory, Washington, DC 20375-5352 (United States); Camilo, Fernando [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Johnson, Tyrel J. [College of Science, George Mason University, Fairfax, VA 22030, USA, resident at Naval Research Laboratory, Washington, DC 20375 (United States); Hessels, Jason W. T.; Bassa, Cees G. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Keane, Evan F. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail H30, P.O. Box 218, VIC 3122 (Australia); Ferrara, Elizabeth C.; Harding, Alice K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-02-10

    XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227−4853, at a dispersion measure of 43.4 pc cm{sup −3} associated with this source, using the Giant Metrewave Radio Telescope (GMRT) at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824−2452I showing evidence of state switching between radio MSP and low-mass X-ray binary states. We report timing observations of PSR J1227−4853 with the GMRT and Parkes, which give a precise determination of the rotational and orbital parameters of the system. The companion mass measurement of 0.17–0.46 M{sub ⊙} suggests that this is a redback system. PSR J1227−4853 is eclipsed for about 40% of its orbit at 607 MHz with additional short-duration eclipses at all orbital phases. We also find that the pulsar is very energetic, with a spin-down luminosity of ∼10{sup 35} erg s{sup −1}. We report simultaneous imaging and timing observations with the GMRT, which suggests that eclipses are caused by absorption rather than dispersion smearing or scattering.

  18. Evaluation of the Agricultural Non-point Source Pollution in Chongqing Based on PSR Model

    Institute of Scientific and Technical Information of China (English)

    Hanwen; ZHANG; Xinli; MOU; Hui; XIE; Hong; LU; Xingyun; YAN

    2014-01-01

    Through a series of exploration based on PSR framework model,for the purpose of building a suitable Chongqing agricultural nonpoint source pollution evaluation index system model framework,combined with the presence of Chongqing specific agro-environmental issues,we build a agricultural non-point source pollution assessment index system,and then study the agricultural system pressure,agro-environmental status and human response in total 3 major categories,develope an agricultural non-point source pollution evaluation index consisting of 3 criteria indicators and 19 indicators. As can be seen from the analysis,pressures and responses tend to increase and decrease linearly,state and complex have large fluctuations,and their fluctuations are similar mainly due to the elimination of pressures and impact,increasing the impact for agricultural non-point source pollution.

  19. LMXB AND IMXB EVOLUTION: I. THE BINARY RADIO PULSAR PSR J1614-2230

    International Nuclear Information System (INIS)

    Lin Jinrong; Rappaport, S.; Podsiadlowski, Ph.; Nelson, L.; Paxton, B.; Todorov, P.

    2011-01-01

    We have computed an extensive grid of binary evolution tracks to represent low- and intermediate-mass X-ray binaries (LMXBs and IMXBs). The grid includes 42,000 models which cover 60 initial donor masses over the range of 1-4 M sun and, for each of these, 700 initial orbital periods over the range of 10-250 hr. These results can be applied to understanding LMXBs and IMXBs: those that evolve analogously to cataclysmic variables, that form ultracompact binaries with P orb in the range of 6-50 minutes, and that lead to wide orbits with giant donors. We also investigate the relic binary recycled radio pulsars into which these systems evolve. To evolve the donor stars in this study, we utilized a newly developed stellar evolution code called 'MESA' that was designed, among other things, to be able to handle very low mass and degenerate donors. This first application of the results is aimed at an understanding of the newly discovered pulsar PSR J1614-2230 which has a 1.97 M sun neutron star, P orb = 8.7 days, and a companion star of 0.5 M sun . We show that (1) this system is a cousin to the LMXB Cyg X-2; (2) for neutron stars of canonical birth mass 1.4 M sun , the initial donor stars which produce the closest relatives to PSR J1614-2230 have a mass between 3.4 and 3.8 M sun ; (3) neutron stars as massive as 1.97 M sun are not easy to produce in spite of the initially high mass of the donor star, unless they were already born as relatively massive neutron stars; (4) to successfully produce a system like PSR J1614-2230 requires a minimum initial neutron-star mass of at least 1.6 ± 0.1 M sun , as well as initial donor masses and P orb of ∼4.25 ± 0.10 M sun and ∼49 ± 2 hr, respectively; and (5) the current companion star is largely composed of CO, but should have a surface H abundance of ∼10%-15%.

  20. Gamma radiation from PSR B1055-52

    DEFF Research Database (Denmark)

    Thompson, D.J.; Bailes, M.; Bertsch, D.L.

    1999-01-01

    The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics that distinguish this pulsar: the light...... curve is complex; there is no detectable unpulsed emission; the energy spectrum is hat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same...

  1. Status of the WNR/PSR at Los Alamos

    International Nuclear Information System (INIS)

    Silver, R.N.

    1982-01-01

    A proton storage ring is presently under construction at Los Alamos for initial operation in 1985 to provide the world's highest peak neutron flux for neutron scattering experiments. The operational WNR pulsed neutron source is in use for TOF instrument development and condensed matter research. Experimental results have been obtained in incoherent inelastic scattering, liquids and powder diffraction, single crystal diffraction and eV spectroscopy using nuclear resonances. Technical problems being addressed include chopper phasing, scintillator detector development, shielding and collimation. A crystal analyzer spectrometer in the constant Q configuration is being assembled. The long range plan for the WNR/PSR facility is described

  2. Novel Polymerase Spiral Reaction (PSR) for rapid visual detection of Bovine Herpesvirus 1 genomic DNA from aborted bovine fetus and semen.

    Science.gov (United States)

    Malla, Javed Ahmed; Chakravarti, Soumendu; Gupta, Vikas; Chander, Vishal; Sharma, Gaurav Kumar; Qureshi, Salauddin; Mishra, Adhiraj; Gupta, Vivek Kumar; Nandi, Sukdeb

    2018-02-20

    Bovine herpesvirus-1 (BHV-1) is a major viral pathogen affecting bovines leading to various clinical manifestations and causes significant economic impediment in modern livestock production system. Rapid, accurate and sensitive detection of BHV-1 infection at frozen semen stations or at dairy herds remains a priority for control of BHV-1 spread to susceptible population. Polymerase Spiral Reaction (PSR), a novel addition in the gamut of isothermal techniques, has been successfully implemented in initial optimization for detection of BHV-1 genomic DNA and further validated in clinical samples. The developed PSR assay has been validated for detection of BHV-1 from bovine semen (n=99), a major source of transmission of BHV-1 from breeding bulls to susceptible dams in artificial insemination programs. The technique has also been used for screening of BHV-1 DNA from suspected aborted fetal tissues (n=25). The developed PSR technique is 100 fold more sensitive than conventional PCR and comparable to real-time PCR. The PSR technique has been successful in detecting 13 samples positive for BHV-1 DNA in bovine semen, 4 samples more than conventional PCR. The aborted fetal tissues were negative for presence of BHV-1 DNA. The presence of BHV-1 in bovine semen samples raises a pertinent concern for extensively screening of semen from breeding bulls before been used for artificial insemination process. PSR has all the attributes for becoming a method of choice for rapid, accurate and sensitive detection of BHV-1 DNA at frozen semen stations or at dairy herds in resource constrained settings. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Phylogenetic distribution and membrane topology of the LytR-CpsA-Psr protein family

    Directory of Open Access Journals (Sweden)

    Berger-Bächi Brigitte

    2008-12-01

    Full Text Available Abstract Background The bacterial cell wall is the target of many antibiotics and cell envelope constituents are critical to host-pathogen interactions. To combat resistance development and virulence, a detailed knowledge of the individual factors involved is essential. Members of the LytR-CpsA-Psr family of cell envelope-associated attenuators are relevant for β-lactam resistance, biofilm formation, and stress tolerance, and they are suggested to play a role in cell wall maintenance. However, their precise function is still unknown. This study addresses the occurrence as well as sequence-based characteristics of the LytR-CpsA-Psr proteins. Results A comprehensive list of LytR-CpsA-Psr proteins was established, and their phylogenetic distribution and clustering into subgroups was determined. LytR-CpsA-Psr proteins were present in all Gram-positive organisms, except for the cell wall-deficient Mollicutes and one strain of the Clostridiales. In contrast, the majority of Gram-negatives did not contain LytR-CpsA-Psr family members. Despite high sequence divergence, the LytR-CpsA-Psr domains of different subclusters shared a highly similar, predicted mixed a/β-structure, and conserved charged residues. PhoA fusion experiments, using MsrR of Staphylococcus aureus, confirmed membrane topology predictions and extracellular location of its LytR-CpsA-Psr domain. Conclusion The LytR-CpsA-Psr domain is unique to bacteria. The presence of diverse subgroups within the LytR-CpsA-Psr family might indicate functional differences, and could explain variations in phenotypes of respective mutants reported. The identified conserved structural elements and amino acids are likely to be important for the function of the domain and will help to guide future studies of the LytR-CpsA-Psr proteins.

  4. PSR J0538+2817 As The Remnant Of The First Supernova Explosion in a Massive Binary

    Science.gov (United States)

    Gvaramadze, V. V.

    2006-08-01

    It is generally accepted that the radio pulsar PSR J0538+2817 is associated with the supernova remnant (SNR) S147. The only problem for the association is the obvious discrepancy (Kramer et al. 2003) between the kinematic age of the system of ~30 kyr (estimated from the angular offset of the pulsar from the geometric center of the SNR and pulsar's proper motion) and the characteristic age of the pulsar of ~600 kyr. To reconcile these ages one can assume that the pulsar was born with a spin period close to the present one (Kramer et al. 2003; Romani & Ng 2003). We propose an alternative explanation of the age discrepancy based on the fact that PSR J0538+2817 could be the stellar remnant of the first supernova explosion in a massive binary system and therefore could be as old as indicated by its characteristic age. Our proposal implies that S147 is the diffuse remnant of the second supernova explosion (that disrupted the binary system) and that a much younger second neutron star (not necessarily manifesting itself as a radio pulsar) should be associated with S147. We use the existing observational data on the system PSR J0538+2817/SNR S147 to suggest that the progenitor of the supernova that formed S147 was a Wolf-Rayet star (so that the supernova explosion occurred within a wind bubble surrounded by a massive shell) and to constrain the parameters of the binary system. We also restrict the magnitude and direction of the kick velocity received by the young neutron star at birth and find that the kick vector should not strongly deviate from the orbital plane of the binary system.

  5. Constraining the gravitational binding energy of PSR J0737-3039B using terrestrial nuclear data

    International Nuclear Information System (INIS)

    Newton, W. G.; Li Baoan

    2009-01-01

    We show that the gravitational binding energy of a neutron star of a given mass is correlated with the slope of the nuclear symmetry energy at 1-2 times nuclear saturation density for equations of state without significant softening (i.e., those that predict maximum masses M max >1.44M · in line with the largest accurately measured neutron star mass). Applying recent laboratory constraints on the slope of the symmetry energy to this correlation we extract a constraint on the baryon mass of the lower mass member of the double pulsar binary system, PSR J0737-3039B. We compare with independent constraints derived from modeling the progenitor star of J0737-3039B up to and through its collapse under the assumption that it formed in an electron capture supernova. The two sets of constraints are consistent only if L < or approx. 70 MeV.

  6. PSR 1913 + 16: endpoints of speculation. A critical discussion of possible companions and progenitors

    Energy Technology Data Exchange (ETDEWEB)

    Webbink, R F [Cambridge Univ. (UK). Inst. of Astronomy

    1975-01-01

    We attempt a comprehensive discussion of the nature and origin of the binary pulsar PSR 1913 + 16. It is shown that the system must have been binary before the creation of the pulsar. Main-sequence stars, white dwarfs, helium stars, neutron stars and black holes are considered as possible secondaries. It is shown that the pulsar component must have been a helium star before collapse. The companion is probably a neutron star, although a helium star or black hole cannot be excluded. We suggest that the pulsar was formed when a moderately massive (2 to 8 M(S)) helium star overfilled its Roche lobe and was stripped of its helium-rich envelope. Core collapse and carbon ignition followed rapidly, creating the neutron star we observe.

  7. Evaluation of Intensive Construction Land Use in the Emerging City Based on PSR-Entropy model

    Science.gov (United States)

    Jia, Yuanyuan; Lei, Guangyu

    2018-01-01

    A comprehensive understanding of emerging city land utilization and the evaluation of intensive land use in the Emerging City will provide the comprehensive and reliable technical basis for the planning and management. It is an important node. According to the Han cheng from 2008 to 2016 years of land use, based on PSR-Entropy model of land use evaluation system, using entropy method to determine the index weight, the introduction of comprehensive index method to evaluate the degree of land use. The results show that the intensive land use comprehensive evaluation index of Han cheng increased from 2008 to 2015, but the land intensive use can not achieve the standards. The potential of further enhancing space is relatively large.

  8. Reconciling Optical and Radio Observations of the Binary Millisecond Pulsar PSR J1640+2224

    Science.gov (United States)

    Vigeland, Sarah J.; Deller, Adam T.; Kaplan, David L.; Istrate, Alina G.; Stappers, Benjamin W.; Tauris, Thomas M.

    2018-03-01

    Previous optical and radio observations of the binary millisecond pulsar PSR J1640+2224 have come to inconsistent conclusions about the identity of its companion, with some observations suggesting that the companion is a low-mass helium-core (He-core) white dwarf (WD), while others indicate that it is most likely a high-mass carbon–oxygen (CO) WD. Binary evolution models predict PSR J1640+2224 most likely formed in a low-mass X-ray binary based on the pulsar’s short spin period and long-period, low-eccentricity orbit, in which case its companion should be a He-core WD with mass about 0.35–0.39 M ⊙, depending on metallicity. If instead it is a CO WD, it would suggest that the system has an unusual formation history. In this paper we present the first astrometric parallax measurement for this system from observations made with the Very Long Baseline Array (VLBA), from which we determine the distance to be {1520}-150+170 {pc}. We use this distance and a reanalysis of archival optical observations originally taken in 1995 with the Wide Field Planetary Camera 2 on the Hubble Space Telescope (HST) to measure the WD’s mass. We also incorporate improvements in calibration, extinction model, and WD cooling models. We find that the existing observations are not sufficient to tightly constrain the companion mass, but we conclude the WD mass is >0.4 M ⊙ with >90% confidence. The limiting factor in our analysis is the low signal-to-noise ratio of the original HST observations.

  9. PSR J2322-2650 - a low-luminosity millisecond pulsar with a planetary-mass companion

    Science.gov (United States)

    Spiewak, R.; Bailes, M.; Barr, E. D.; Bhat, N. D. R.; Burgay, M.; Cameron, A. D.; Champion, D. J.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Kulkarni, S. R.; Levin, L.; Lyne, A. G.; Morello, V.; Ng, C.; Possenti, A.; Ravi, V.; Stappers, B. W.; van Straten, W.; Tiburzi, C.

    2018-03-01

    We present the discovery of a binary millisecond pulsar (MSP), PSR J2322-2650, found in the southern section of the High Time Resolution Universe survey. This system contains a 3.5-ms pulsar with a ˜10-3 M⊙ companion in a 7.75-h circular orbit. Follow-up observations at the Parkes and Lovell telescopes have led to precise measurements of the astrometric and spin parameters, including the period derivative, timing parallax, and proper motion. PSR J2322-2650 has a parallax of 4.4 ± 1.2 mas, and is thus at an inferred distance of 230^{+90}_{-50} pc, making this system a candidate for optical studies. We have detected a source of R ≈ 26.4 mag at the radio position in a single R-band observation with the Keck telescope, and this is consistent with the blackbody temperature we would expect from the companion if it fills its Roche lobe. The intrinsic period derivative of PSR J2322-2650 is among the lowest known, 4.4(4) × 10-22 s s-1, implying a low surface magnetic field strength, 4.0(4) × 107 G. Its mean radio flux density of 160 μJy combined with the distance implies that its radio luminosity is the lowest ever measured, 0.008(5) mJy kpc2. The inferred population of these systems in the Galaxy may be very significant, suggesting that this is a common MSP evolutionary path.

  10. The Glitches and Rotational History of the Highly Energetic Young Pulsar PSR J0537–6910

    Science.gov (United States)

    Ferdman, R. D.; Archibald, R. F.; Gourgouliatos, K. N.; Kaspi, V. M.

    2018-01-01

    We present a timing and glitch analysis of the young X-ray pulsar PSR J0537‑6910, located within the Large Magellanic Cloud, using 13 yr of data from the now-decommissioned Rossi X-ray Timing Explorer. Rotating with a spin period of 16 ms, PSR J0537‑6910 is the fastest-spinning and most energetic young pulsar known. It also displays the highest glitch activity of any known pulsar. We have found 42 glitches over the data span, corresponding to a glitch rate of 3.2 yr‑1, with an overall glitch activity rate of 8.8× {10}-7 {{yr}}-1. The high glitch frequency has allowed us to study the glitch behavior in ways that are inaccessible in other pulsars. We observe a strong linear correlation between spin frequency glitch magnitude and wait time to the following glitch. We also find that the post-glitch spin-down recovery is well described by a single two-component model fit to all glitches for which we have adequate input data. This consists of an exponential amplitude A=(7.6+/- 1.0)× {10}-14 {{{s}}}-2, decay timescale τ ={27}-6+7 {day}s, and linear slope m=(4.1+/- 0.4)× {10}-16 {{{s}}}-2 {{day}}-1. The latter slope corresponds to a second frequency derivative \\ddot{ν }=(4.7+/- 0.5)× {10}-22 {{{s}}}-3, from which we find an implied braking index n=7.4+/- 0.8. We also present a maximum likelihood technique for searching for periods in event-time data, which we used to both confirm previously published values and determine rotation frequencies in later observations. We discuss the implied constraints on glitch models from the observed behavior of this system, which we argue cannot be fully explained in the context of existing theories.

  11. Methods and Effects of Safety Enhancement in Korean PSR

    International Nuclear Information System (INIS)

    Kim, Young Gab; Park, Jong Woon

    2009-01-01

    Periodic Safety Review (PSR) is a comprehensive study on a nuclear power plant safety, taking into account aspects such as operational history, ageing, safety analyses and advances in code and standards since the time of construction. In Korea, PSRs have been performed for 20 units and have been effectively used to obtain an overall view of actual plant safety to determine reasonable and practical modifications that should be made in order to obtain a higher level of safety approaching that of modern plants. Among many safety enhancements achieved from Korean PSRs, new safety analyses are the important methods to confirm plant safety by increasing safety margin for specific safety issues. Methods and effects of safety enhancements applied in Korean PSRs are reviewed in this paper in light of new safety analyses to obtain additional safety margins

  12. Search for VHE γ-ray emission from the direction of the two millisecond pulsars PSR J0437-4715 and PSR J1824-2452 and the composite supernova remnant Kes 75 with H.E.S.S

    International Nuclear Information System (INIS)

    Fuessling, Matthias

    2012-01-01

    This work reports on the search for pulsed and steady very-high energy (VHE) gamma-ray emission in the energy range extending from 100 GeV up to 100 TeV from the direction of three pulsars with the High Energy Stereoscopic System (H.E.S.S.). Pulsed gamma-ray radiation from pulsars with energies beyond 100 GeV was found thus far only for the young and energetic Crab pulsar. A special class of pulsar wind nebulae (PWNe) is associated with composite supernova remnants (SNRs) where the PWN is centered in an expanding SNR shell. In the first part of this thesis, the results on the search for pulsed and steady VHE gamma-ray emission from the two millisecond pulsars, PSR J0437-4715 and PSR J1824-2452, are presented. Parts of the observations were conducted in a special trigger setup (the topological trigger with convergent pointing) to reduce the energy threshold of the instrument. No signal of pulsed or steady emission is found and upper limits on the pulsed and steady gamma-ray flux are derived. The upper limits on the pulsed gamma-ray flux are compared to existing model predictions and, in the case of PSR J1824-2452, allow the range of possible viewing geometries in some models to be constrained. In the second part of this work, results on the search for pulsed and steady VHE gamma-ray emission from the direction of the composite SNR Kes 75 are presented. The PWN in the center of Kes 75 is powered by a very young and powerful pulsar, PSR J1846-0258, that has an exceptionally high magnetic field. While no hint for pulsed emission is found, steady VHE gamma-ray emission is detected with a statistical significance of 10 sigma from a point-like source. The VHE gamma-ray emission is spatially coincident with the PWN and the SNR shell. Both are discussed as a possible origin for the observed emission. The pulsar of Kes 75 would be the youngest pulsar known to date to power a VHE PWN.

  13. Detection by Sardinia Radio Telescope of radio pulses at 7 GHz from the Magnetar PSR J1745-2900 in the Galactic center region

    Science.gov (United States)

    Buttu, Marco; D'Amico, Nichi; Egron, Elise; Iacolina, Maria Noemi; Marongiu, Pasqualino; Migoni, Carlo; Pellizzoni, Alberto; Poppi, Sergio; Possenti, Andrea; Trois, Alessio; Vargiu, Gian Paolo

    2013-05-01

    During the Sardinia Radio Telescope (SRT) science verification phase, we observed PSR J1745-2900, firstly detected as an X-ray flare from Sgr A* by Swift and then identified as a 3.76 s X-ray magnetar with NuSTAR telescope (ATels #5006, #5020, #5027, #5032, #5033, #5035), at a central frequency of 7.30 GHz. We used a Beam Wave Guide focus cryogenically cooled receiver (system temperature ~25 K).

  14. A 1.05 M{sub ☉} companion to PSR J2222–0137: The coolest known white dwarf?

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, David L. [Department of Physics, University of Wisconsin-Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Boyles, Jason; McLaughlin, Maura A.; Lorimer, Duncan R. [Department of Physics and Astronomy, West Virginia University, White Hall, Box 6315, Morgantown, WV 26506-6315 (United States); Dunlap, Bart H. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); Tendulkar, Shriharsh P. [Space Radiation Laboratory, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Deller, Adam T. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Ransom, Scott M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Stairs, Ingrid H., E-mail: kaplan@uwm.edu [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada)

    2014-07-10

    The recycled pulsar PSR J2222–0137 is one of the closest known neutron stars (NSs) with a parallax distance of 267{sub −0.9}{sup +1.2} pc and an edge-on orbit. We measure the Shapiro delay in the system through pulsar timing with the Green Bank Telescope, deriving a low pulsar mass (1.20 ± 0.14 M{sub ☉}) and a high companion mass (1.05 ± 0.06 M{sub ☉}) consistent with either a low-mass NS or a high-mass white dwarf. We can largely reject the NS hypothesis on the basis of the system's extremely low eccentricity (3 × 10{sup –4})—too low to have been the product of two supernovae under normal circumstances. However, despite deep optical and near-infrared searches with Southern Astrophysical Research and the Keck telescopes we have not discovered the optical counterpart of the system. This is consistent with the white dwarf hypothesis only if the effective temperature is <3000 K, a limit that is robust to distance, mass, and atmosphere uncertainties. This would make the companion to PSR J2222–0137 one of the coolest white dwarfs ever observed. For the implied age to be consistent with the age of the Milky Way requires the white dwarf to have already crystallized and entered the faster Debye-cooling regime.

  15. A 1.05 M☉ companion to PSR J2222–0137: The coolest known white dwarf?

    International Nuclear Information System (INIS)

    Kaplan, David L.; Boyles, Jason; McLaughlin, Maura A.; Lorimer, Duncan R.; Dunlap, Bart H.; Tendulkar, Shriharsh P.; Deller, Adam T.; Ransom, Scott M.; Stairs, Ingrid H.

    2014-01-01

    The recycled pulsar PSR J2222–0137 is one of the closest known neutron stars (NSs) with a parallax distance of 267 −0.9 +1.2 pc and an edge-on orbit. We measure the Shapiro delay in the system through pulsar timing with the Green Bank Telescope, deriving a low pulsar mass (1.20 ± 0.14 M ☉ ) and a high companion mass (1.05 ± 0.06 M ☉ ) consistent with either a low-mass NS or a high-mass white dwarf. We can largely reject the NS hypothesis on the basis of the system's extremely low eccentricity (3 × 10 –4 )—too low to have been the product of two supernovae under normal circumstances. However, despite deep optical and near-infrared searches with Southern Astrophysical Research and the Keck telescopes we have not discovered the optical counterpart of the system. This is consistent with the white dwarf hypothesis only if the effective temperature is <3000 K, a limit that is robust to distance, mass, and atmosphere uncertainties. This would make the companion to PSR J2222–0137 one of the coolest white dwarfs ever observed. For the implied age to be consistent with the age of the Milky Way requires the white dwarf to have already crystallized and entered the faster Debye-cooling regime.

  16. Fermi LAT Detection of Pulsed Gamma-Rays From the Vela-Like Pulsars PSR J1048-5832 and PSR J2229+6114

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A.A.; /Naval Research Lab, Wash., D.C. /Federal City Coll.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U. /Stockholm U., OKC; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Baring, M.G.; /Rice U.; Bastieri, D.; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, E.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Columbia U. /IASF, Milan /Milan Polytechnic /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Naval Research Lab, Wash., D.C. /George Mason U. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /LPCE, Orleans /Montpellier U. /Stockholm U. /Stockholm U., OKC /INFN, Trieste /Bari U. /INFN, Bari /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /INFN, Trieste /Arecibo Observ. /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Bari U. /INFN, Bari /INFN, Bari /NASA, Goddard /Maryland U. /INFN, Perugia /Perugia U.; /more authors..

    2012-03-29

    We report the detection of {gamma}-ray pulsations ({ge}0.1 GeV) from PSR J2229+6114 and PSR J1048-5832, the latter having been detected as a low-significance pulsar by EGRET. Data in the {gamma}-ray band were acquired by the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope, while the radio rotational ephemerides used to fold the {gamma}-ray light curves were obtained using the Green Bank Telescope, the Lovell telescope at Jodrell Bank, and the Parkes Telescope. The two young radio pulsars, located within the error circles of the previously unidentified EGRET sources 3EG J1048-5840 and 3EG J2227+6122, present spin-down characteristics similar to the Vela pulsar. PSR J1048-5832 shows two sharp peaks at phases 0.15 {+-} 0.01 and 0.57 {+-} 0.01 relative to the radio pulse confirming the EGRET light curve, while PSR J2229+6114 presents a very broad peak at phase 0.49 {+-} 0.01. The {gamma}-ray spectra above 0.1 GeV of both pulsars are fit with power laws having exponential cutoffs near 3 GeV, leading to integral photon fluxes of (2.19 {+-} 0.22 {+-} 0.32) x 10{sup -7} cm{sup -2} s{sup -1} for PSR J1048-5832 and (3.77 {+-} 0.22 {+-} 0.44) x 10{sup -7} cm{sup -2} s{sup -1} for PSR J2229+6114. The first uncertainty is statistical and the second is systematic. PSR J1048-5832 is one of the two LAT sources which were entangled together as 3EG J1048-5840. These detections add to the growing number of young {gamma}-ray pulsars that make up the dominant population of GeV {gamma}-ray sources in the Galactic plane.

  17. Kepler K2 observations of the transitional millisecond pulsar PSR J1023+0038

    Science.gov (United States)

    Kennedy, M. R.; Clark, C. J.; Voisin, G.; Breton, R. P.

    2018-06-01

    For 80 d in 2017, the Kepler Space Telescope continuously observed the transitional millisecond pulsar system PSR J1023+0038 in its accreting state. We present analyses of the 59-s cadence data, focusing on investigations of the orbital light curve of the irradiated companion star and of flaring activity in the neutron star's accretion disc. The underlying orbital modulation from the companion star retains a similar amplitude and asymmetric heating profile as seen in previous photometric observations of the system in its radio pulsar state, suggesting that the heating mechanism has not been affected by the state change. We also find tentative evidence that this asymmetry may vary with time. The light curve also exhibits `flickering' activity, evident as short time-scale flux correlations throughout the observations, and periods of rapid mode-switching activity on time-scales shorter than the observation cadence. Finally, the system spent ˜ 20 per cent of the observations in a flaring state, with the length of these flares varying from <2 min up to several hours. The flaring behaviour is consistent with a self-organized criticality mechanism, most likely related to the build-up and release of mass at the inner edge of the accretion disc.

  18. A VERY LARGE GLITCH IN PSR B2334+61

    International Nuclear Information System (INIS)

    Yuan, J. P.; Wang, N.; Zhou, X.; Liu, Z. Y.; Gao, Z. F.; Manchester, R. N.

    2010-01-01

    Seven year pulse time-of-arrival measurements have been collected from observations of the young pulsar PSR B2334+61 using the Nanshan radio telescope of Urumqi Observatory. A phase-connected solution has been obtained over the whole data span, 2002 August to 2009 August. This includes a very large glitch that occurred between 2005 August 26 and September 8 (MJDs 53608 and 53621). The relative increase in rotational frequency for this glitch, Δν g /ν ∼ 20.5 x 10 -6 , is the largest ever seen. Although accounting for less than 1% of the glitch, there were two well-defined exponential decay terms with time constants of 21 and 147 days, respectively. There was also a large long-term increase in the spin-down rate with Δν-dit p /ν-dot ∼0.011 at the time of the glitch. A highly significant oscillation with a period of close to one year is seen in the post-glitch residuals. It is very unlikely that this can be accounted for by a pulsar position error or proper motion-it appears to result from effects interior to the neutron star. Implications of these results for pulsar glitch models are discussed.

  19. Multiwavelength Spectroscopy of PSR B0656+14

    Science.gov (United States)

    Durant, Martin; Kargaltsev, Oleg; Pavlov, George G.

    2011-12-01

    Using high-quality Hubble Space Telescope observations, we construct the near-infrared (NIR) to far-ultraviolet (FUV) spectral energy distribution (SED) of PSR B0656+14. The SED is non-monotonic. Fitting it with a simple combination of a Rayleigh-Jeans spectrum (UV) and non-thermal power law (PL; optical/NIR) leaves significant residuals, strongly hinting at one or more spectral features. We consider various models (combination of continuum components, and absorption/emission lines) with possible interpretations and place them in the context of the broader SED. Surprisingly, the extrapolation of the best-fit X-ray spectral model roughly matches the NIR-FUV data, and the PL component is also consistent with the γ-ray fluxes. We compare the multiwavelength SED of B0656+14 with those of other optical-, X-ray-, and γ-ray-detected pulsars, and notice that a simple PL spectrum crudely accounts for most of the non-thermal emission.

  20. MULTIWAVELENGTH SPECTROSCOPY OF PSR B0656+14

    International Nuclear Information System (INIS)

    Durant, Martin; Kargaltsev, Oleg; Pavlov, George G.

    2011-01-01

    Using high-quality Hubble Space Telescope observations, we construct the near-infrared (NIR) to far-ultraviolet (FUV) spectral energy distribution (SED) of PSR B0656+14. The SED is non-monotonic. Fitting it with a simple combination of a Rayleigh-Jeans spectrum (UV) and non-thermal power law (PL; optical/NIR) leaves significant residuals, strongly hinting at one or more spectral features. We consider various models (combination of continuum components, and absorption/emission lines) with possible interpretations and place them in the context of the broader SED. Surprisingly, the extrapolation of the best-fit X-ray spectral model roughly matches the NIR-FUV data, and the PL component is also consistent with the γ-ray fluxes. We compare the multiwavelength SED of B0656+14 with those of other optical-, X-ray-, and γ-ray-detected pulsars, and notice that a simple PL spectrum crudely accounts for most of the non-thermal emission.

  1. Timing irregularities of PSR J1705-1906

    Science.gov (United States)

    Liu, Y. L.; Yuan, J. P.; Wang, J. B.; Liu, X. W.; Wang, N.; Yuen, R.

    2018-05-01

    Timing analysis of PSR J1705-1906 using data from Nanshan 25-m and Parkes 64-m radio telescopes, which span over fourteen years, shows that the pulsar exhibits significant proper motion, and rotation instability. We updated the astrometry parameters and the spin parameters of the pulsar. In order to minimize the effect of timing irregularities on measuring its position, we employ the Cholesky method to analyse the timing noise. We obtain the proper motion of -77(3) mas yr-1 in right ascension and -38(29) mas yr-1 in declination. The power spectrum of timing noise is analyzed for the first time, which gives the spectral exponent α =-5.2 for the power-law model indicating that the fluctuations in spin frequency and spin-down rate dominate the red noise. We detect two small glitches from this pulsar with fractional jump in spin frequency of Δ ν /ν ˜ 2.9 × 10^{-10} around MJD 55199 and Δ ν /ν ˜ 2.7× 10^{-10} around MJD 55953. Investigations of pulse profile at different time segments suggest no significant changes in the pulse profiles around the two glitches.

  2. Post design evaluation (ageing mechanisms, effects, management, monitoring, PSR, ISI)

    International Nuclear Information System (INIS)

    Ichikawa, Toshio

    2001-01-01

    Although the nuclear plant was designed for the purpose of the 30-year life the early stages of construction, it also already has the plant abolished by passing in 30 years. There is a plant under operation and a plant that is employed variously, extends the original life and continues operation now, and the plant that is going to be abolished politically is before a life. By using a nuclear plant for a long period of time, damage. by the influence of irradiation, wear of slipping, corrosion, etc. appears. When this degradation is left, the serious accident is caused. In this lecture, refer to Assessment and management of ageing of major nuclear power plant components important to safety, Oct. 1999 of IAEA. A point of view from guide is introduced about management of the mechanism in the secular degradation mode expected by operating for a long period of time, the influence of secular degradation, and influence, monitoring technology, periodical safe evaluation, and a periodic inspection. And raises and explains the correspondence situation of secular degradation, and the example of evaluation of PSR and ISI equipment. The aging mechanism for reactor vessel internal components considered are related to embrittlement, fatigue, corrosion, radiation induced creep, relaxation and swelling, and mechanical wear. This lecture includes; monitoring methods, a description of periodic safety reviews and a sample of seismic design periodic safety report for the reactor internals

  3. A PRECISE MASS MEASUREMENT OF THE INTERMEDIATE-MASS BINARY PULSAR PSR J1802 - 2124

    International Nuclear Information System (INIS)

    Ferdman, R. D.; Cognard, I.; Desvignes, G.; Theureau, G.; Stairs, I. H.; Kramer, M.; McLaughlin, M. A.; Lorimer, D. R.; Nice, D. J.; Manchester, R. N.; Hobbs, G.; Lyne, A. G.; Faulkner, A.; Camilo, F.; Possenti, A.; Demorest, P. B.; Backer, D. C.

    2010-01-01

    PSR J1802 - 2124 is a 12.6 ms pulsar in a 16.8 hr binary orbit with a relatively massive white dwarf (WD) companion. These properties make it a member of the intermediate-mass class of binary pulsar (IMBP) systems. We have been timing this pulsar since its discovery in 2002. Concentrated observations at the Green Bank Telescope, augmented with data from the Parkes and Nancay observatories, have allowed us to determine the general relativistic Shapiro delay. This has yielded pulsar and WD mass measurements of 1.24 ± 0.11 M sun and 0.78 ± 0.04 M sun (68% confidence), respectively. The low mass of the pulsar, the high mass of the WD companion, the short orbital period, and the pulsar spin period may be explained by the system having gone through a common-envelope phase in its evolution. We argue that selection effects may contribute to the relatively small number of known IMBPs.

  4. PSR J1618-3921: a recycled pulsar in an eccentric orbit

    Science.gov (United States)

    Octau, F.; Cognard, I.; Guillemot, L.; Tauris, T. M.; Freire, P. C. C.; Desvignes, G.; Theureau, G.

    2018-04-01

    Context. The 11.99 ms pulsar PSR J1618-3921 orbits a He white dwarf companion of probably low mass with a period of 22.7 d. The pulsar was discovered in a survey of the intermediate Galactic latitudes at 1400 MHz that was conducted with the Parkes radio telescope in the late 1990s. Although PSR J1618-3921 was discovered more than 15 years ago, only limited information has been published about this pulsar, which has a surprisingly high orbital eccentricity (e ≃ 0.027) considering its high spin frequency and the likely low mass of the companion. Aims: The focus of this work is a precise measurement of the spin and the astrometric and orbital characteristics of PSR J1618-3921. This was done with timing observations made at the Nançay Radio Telescope from 2009 to 2017. Methods: We analyzed the timing data recorded at the Nançay Radio Telescope over several years to characterize the properties of PSR J1618-3921. A rotation ephemeris for this pulsar was obtained by analyzing the arrival times of the radio pulses at the telescope. Results: We confirm the unusual eccentricity of PSR J1618-3921 and discuss several hypotheses regarding its formation in the context of other discoveries of recycled pulsars in eccentric orbits.

  5. Anti-correlated X-ray and Radio Variability in the Transitional Millisecond Pulsar PSR J1023+0038

    Science.gov (United States)

    Bogdanov, Slavko; Deller, Adam; Miller-Jones, James; Archibald, Anne; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D'Angelo, Caroline

    2018-01-01

    The PSR J1023+0038 binary system hosts a 1.69-ms neutron star and a low-mass, main-sequence-like star. The system underwent a transformation from a rotation-powered to a low-luminosity accreting state in 2013 June, in which it has remained since. We present an unprecedented set of strictly simultaneous Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations, which for the first time reveal a highly reproducible, anti-correlated variability pattern. Rapid declines in X-ray flux are always accompanied by a radio brightening with duration that closely matches the low X-ray flux mode intervals. We discuss these findings in the context of accretion and jet outflow physics and their implications for using the radio/X-ray luminosity plane to distinguish low-luminosity candidate black hole binary systems from accreting transitional millisecond pulsars.

  6. Testing the strong equivalence principle with the triple pulsar PSR J 0337 +1715

    Science.gov (United States)

    Shao, Lijing

    2016-04-01

    Three conceptually different masses appear in equations of motion for objects under gravity, namely, the inertial mass, mI , the passive gravitational mass, mP, and the active gravitational mass, mA. It is assumed that, for any objects, mI=mP=mA in the Newtonian gravity, and mI=mP in the Einsteinian gravity, oblivious to objects' sophisticated internal structure. Empirical examination of the equivalence probes deep into gravity theories. We study the possibility of carrying out new tests based on pulsar timing of the stellar triple system, PSR J 0337 +1715 . Various machine-precision three-body simulations are performed, from which, the equivalence-violating parameters are extracted with Markov chain Monte Carlo sampling that takes full correlations into account. We show that the difference in masses could be probed to 3 ×1 0-8 , improving the current constraints from lunar laser ranging on the post-Newtonian parameters that govern violations of mP=mI and mA=mP by thousands and millions, respectively. The test of mP=mA would represent the first test of Newton's third law with compact objects.

  7. Improving prediction accuracy of cooling load using EMD, PSR and RBFNN

    Science.gov (United States)

    Shen, Limin; Wen, Yuanmei; Li, Xiaohong

    2017-08-01

    To increase the accuracy for the prediction of cooling load demand, this work presents an EMD (empirical mode decomposition)-PSR (phase space reconstruction) based RBFNN (radial basis function neural networks) method. Firstly, analyzed the chaotic nature of the real cooling load demand, transformed the non-stationary cooling load historical data into several stationary intrinsic mode functions (IMFs) by using EMD. Secondly, compared the RBFNN prediction accuracies of each IMFs and proposed an IMF combining scheme that is combine the lower-frequency components (called IMF4-IMF6 combined) while keep the higher frequency component (IMF1, IMF2, IMF3) and the residual unchanged. Thirdly, reconstruct phase space for each combined components separately, process the highest frequency component (IMF1) by differential method and predict with RBFNN in the reconstructed phase spaces. Real cooling load data of a centralized ice storage cooling systems in Guangzhou are used for simulation. The results show that the proposed hybrid method outperforms the traditional methods.

  8. An approach for Periodic Safety Review (PSR) of units 5 and 6 of Kozloduy NPP

    International Nuclear Information System (INIS)

    Kichev, Emil

    2014-01-01

    Periodic Safety Reviews (PSR) is complementary to the routine and special safety reviews and does not replaced them. It determines the level of compliance with current safety requirements and covers all safety aspects of NPP operation and all equipment (SSCs) on site. Three levels of importance are defined for the documents in PSR (towards higher conservatism): Bulgarian documents; IAEA documents; Documents of manufactures and suppliers of the equipment (SSCs). The scope and activities consists of four stages and includes 14 safety factors (SF). Cooperation with external companies and organizations in areas with proved experience is used.

  9. NuSTAR Observations of the State Transition of Millisecond Pulsar Binary PSR J1023+0038

    DEFF Research Database (Denmark)

    Tendulkar, Shriharsh P.; Yang, Chengwei; An, Hongjun

    2014-01-01

    We report NuSTAR observations of the millisecond pulsar - low mass X-ray binary (LMXB) transition system PSR J1023+0038 from June and October 2013, before and after the formation of an accretion disk around the neutron star. Between June 10-12, a few days to two weeks before the radio disappearance...... and current multi-wavelength observations and show the hard X-ray power law extending to 79 keV without a spectral break. Sharp edged, flat bottomed `dips' are observed with widths between 30-1000 s and ingress and egress time-scales of 30-60 s. No change in hardness ratio was observed during the dips...

  10. RELATIVISTIC MEASUREMENTS FROM TIMING THE BINARY PULSAR PSR B1913+16

    Energy Technology Data Exchange (ETDEWEB)

    Weisberg, J. M.; Huang, Y., E-mail: jweisber@carleton.edu [Department of Physics and Astronomy, Carleton College, Northfield, MN 55057 (United States)

    2016-09-20

    We present relativistic analyses of 9257 measurements of times-of-arrival from the first binary pulsar, PSR B1913+16, acquired over the last 35 years. The determination of the “Keplerian” orbital elements plus two relativistic terms completely characterizes the binary system, aside from an unknown rotation about the line of sight, leading to a determination of the masses of the pulsar and its companion: 1.438 ± 0.001 M {sub ☉} and 1.390 ± 0.001 M {sub ☉}, respectively. In addition, the complete system characterization allows for the creation of relativistic gravitation test by comparing measured and predicted sizes of various relativistic phenomena. We find that the ratio of the observed orbital period decrease caused by gravitational wave damping (corrected by a kinematic term) to the general relativistic prediction is 0.9983 ± 0.0016, thereby confirms the existence and strength of gravitational radiation as predicted by general relativity. For the first time in this system, we have also successfully measured the two parameters characterizing the Shapiro gravitational propagation delay, and found that their values are consistent with general relativistic predictions. For the first time in any system, we have also measured the relativistic shape correction to the elliptical orbit, δ {sub θ} , although its intrinsic value is obscured by currently unquantified pulsar emission beam aberration. We have also marginally measured the time derivative of the projected semimajor axis, which, when improved in combination with beam aberration modeling from geodetic precession observations, should ultimately constrain the pulsar’s moment of inertia.

  11. The paternal-sex-ratio (PSR) chromosome in natural populations of Nasonia (Hymenoptera Chalcidoidea)

    NARCIS (Netherlands)

    Beukeboom, L.W.; Werren, J.H.

    2000-01-01

    Selfish genetic elements may be important in promoting evolutionary change. Paternal sex ratio (PSR) is a selfish B chromosome that causes all-male families in the haplodiploid parasitic wasp Nasonia vitripennis, by inducing paternal genome loss in fertilized eggs. The natural distribution and

  12. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed 'magnetar-like' variability, a particularly interesting case is that of PSR B0943+10. Recent observations have shown ...

  13. Experience with Periodic Safety Review (PSR) at Kozloduy NPP after 20 years of operation

    International Nuclear Information System (INIS)

    Popov, V.

    2011-01-01

    Conclusion: Measures in the long-term Programs for improving safety and radiation protection of unit 5&6, based on PSR outcome and addressed on the units’ operation licence renewal are under way. • NPP Kozloduy intends to fulfils requirements on modern nuclear power plants which occasionally exceeds limits of the effective national nuclear legislation

  14. Discovery of the Millisecond Pulsar PSR J2043+1711 in a Fermi Source with the Nancay Radio Telescope

    Science.gov (United States)

    Guillemot, L.; Freire, P. C. C.; Cognard, I.; Johnson, T. J.; Takahashi, Y.; Kataoka, J.; Desvignes, G.; Camilo, F.; Ferrara, E. C.; Harding, A. K.; hide

    2012-01-01

    We report the discovery of the millisecond pulsar PSR J2043+1711 in a search of a Fermi Large Area Telescope (LAT) source with no known associations, with the Nancay Radio Telescope. The new pulsar, confirmed with the Green Bank Telescope, has a spin period of 2.38 ms, is relatively nearby (d approx. pulsars seen with Fermi. X-ray observations of the pulsar with Suzaku and the Swift X-ray Telescope yielded no detection. At 1.4 GHz, we observe strong flux density variations because of interstellar diffractive scintillation; however, a sharp peak can be observed at this frequency during bright scintillation states. At 327 MHz, the pulsar is detected with a much higher signal-to-noise ratio and its flux density is far more steady. However, at that frequency the Arecibo instrumentation cannot yet fully resolve the pulse profile. Despite that, our pulse time-of-arrival measurements have a post-fit residual rms of 2 micro s. This and the expected stability of this system have made PSR J2043+1711 one of the first new Fermi-selected millisecond pulsars to be added to pulsar gravitational wave timing arrays. It has also allowed a significant measurement of relativistic delays in the times of arrival of the pulses due to the curvature of space-time near the companion, but not yet with enough precision to derive useful masses for the pulsar and the companion. Nevertheless, a mass for the pulsar between 1.7 and 2.0 solar Mass can be derived if a standard millisecond pulsar formation model is assumed. In this paper, we also present a comprehensive summary of pulsar searches in Fermi LAT sources with the Nancay Radio Telescope to date.

  15. Discovery of a Synchrotron Bubble Associated with PSR J1015–5719

    International Nuclear Information System (INIS)

    Ng, C.-Y.; Bandiera, R.; Hunstead, R. W.; Johnston, S.

    2017-01-01

    We report the discovery of a synchrotron nebula, G283.1−0.59, associated with PSR J1015−5719. Radio observations using the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array at 36, 16, 6, and 3 cm reveal a complex morphology. The pulsar is embedded in the “head” of the nebula with fan-shaped diffuse emission. This is connected to a circular bubble of 20″ radius and a collimated tail extending over 1′. Polarization measurements show a highly ordered magnetic field in the nebula. It wraps around the edge of the head and shows an azimuthal configuration near the pulsar, then switches direction quasi-periodically near the bubble and in the tail. Together with the flat radio spectrum observed, we suggest that this system is most plausibly a pulsar wind nebula (PWN), with the head as a bow shock that has a low Mach number and the bubble as a shell expanding in a dense environment. The bubble could act as a magnetic bottle trapping the relativistic particles. A comparison with other bow-shock PWNe with higher Mach numbers shows similar structure and B -field geometry, implying that pulsar velocity may not be the most critical factor in determining the properties of these systems. We also derive analytic expressions for the projected standoff distance and shape of an inclined bow shock. It is found that the projected distance is always larger than the true distance in three dimensions. On the other hand, the projected shape is not sensitive to the inclination after rescaling with the projected standoff distance.

  16. Discovery of a Synchrotron Bubble Associated with PSR J1015–5719

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.-Y. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Bandiera, R. [Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Hunstead, R. W. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Johnston, S., E-mail: ncy@bohr.physics.hku.hk [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia)

    2017-06-20

    We report the discovery of a synchrotron nebula, G283.1−0.59, associated with PSR J1015−5719. Radio observations using the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array at 36, 16, 6, and 3 cm reveal a complex morphology. The pulsar is embedded in the “head” of the nebula with fan-shaped diffuse emission. This is connected to a circular bubble of 20″ radius and a collimated tail extending over 1′. Polarization measurements show a highly ordered magnetic field in the nebula. It wraps around the edge of the head and shows an azimuthal configuration near the pulsar, then switches direction quasi-periodically near the bubble and in the tail. Together with the flat radio spectrum observed, we suggest that this system is most plausibly a pulsar wind nebula (PWN), with the head as a bow shock that has a low Mach number and the bubble as a shell expanding in a dense environment. The bubble could act as a magnetic bottle trapping the relativistic particles. A comparison with other bow-shock PWNe with higher Mach numbers shows similar structure and B -field geometry, implying that pulsar velocity may not be the most critical factor in determining the properties of these systems. We also derive analytic expressions for the projected standoff distance and shape of an inclined bow shock. It is found that the projected distance is always larger than the true distance in three dimensions. On the other hand, the projected shape is not sensitive to the inclination after rescaling with the projected standoff distance.

  17. Ecological Security Assessment of Hebei by PSR Model%基于PSR模型的河北省生态安全评价研究

    Institute of Scientific and Technical Information of China (English)

    杨红倩

    2017-01-01

    着眼于河北省粗放型经济发展模式与日益恶劣的生态环境之间的矛盾,基于"压力-状态-响应"(PSR)模型,选取人口、环境、资源、社会经济等方面30个指标,构建河北省生态安全评价指标体系,利用熵值法从时间尺度上对河北省生态安全状况进行综合评价与分析.结果表明:2005-2014年间,河北省生态安全综合评价指数整体呈现上升趋势,说明河北省的生态安全状况有所好转.最后提出加强河北省生态安全建设的对策思路,为建设成为生态强省提供依据.%Focus on extensive economic development mode in Hebei Province and the contradiction between the increasingly severe ecological environment, based on the "pressure-state-response"(PSR)and the stress-state-response(PSR)model, this paper selects 30 indicators of population, environment, resources, socio-economy to construct the ecological security evaluation index system of Hebei Province, which used to evaluate and analyze the ecological security situation of Hebei Province from the time scale by entropy method.The results showed that the overall ecological security index of Hebei Province showed an upward trend in 2005-2014, which indicated that the ecological security situation of Hebei Province had improved.Finally, the countermeasures to strengthen the ecological security construction in Hebei Province are put forward, which will provide the basis for building a strong ecological province.

  18. HIGH-ENERGY OBSERVATIONS OF PSR B1259–63/LS 2883 THROUGH THE 2014 PERIASTRON PASSAGE: CONNECTING X-RAYS TO THE GeV FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Tam, P. H. T.; Li, K. L.; Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Takata, J. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Okazaki, A. T. [Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan); Hui, C. Y., E-mail: phtam@phys.nthu.edu.tw [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

    2015-01-01

    The binary system PSR B1259–63/LS 2883 is well sampled in radio, X-rays, and TeV γ-rays, and shows orbital-phase-dependent variability in these frequencies. The first detection of GeV γ-rays from the system was made around the 2010 periastron passage. In this Letter, we present an analysis of X-ray and γ-ray data obtained by the Swift/XRT, NuSTAR/FPM, and Fermi/LAT, through the recent periastron passage which occurred on 2014 May 4. While PSR B1259–63/LS 2883 was not detected by the Large Area Telescope before and during this passage, we show that the GeV flares occurred at a similar orbital phase as in early 2011, thus establishing the repetitive nature of the post-periastron GeV flares. Multiple flares each lasting for a few days have been observed and short-term variability is seen as well. We also found X-ray flux variation contemporaneous with the GeV flare for the first time. Strong evidence of the keV-to-GeV connection came from the broadband high-energy spectra, which we interpret as synchrotron radiation from the shocked pulsar wind.

  19. Discovery of a radio nebula around PSR J0855-4644

    Science.gov (United States)

    Maitra, C.; Roy, S.; Acero, F.; Gupta, Y.

    2018-03-01

    We report the discovery of a diffuse radio emission around PSR J0855-4644 using an upgraded GMRT (uGMRT) observation at 1.35 GHz. The radio emission is spatially coincident with the diffuse X-ray pulsar wind nebula (PWN) seen with XMM-Newton but is much larger in extent compared to the compact axisymmetric PWN seen with Chandra. The morphology of the emission, with a bright partial ring-like structure and two faint tail-like features strongly resembles a bow shock nebula, and indicates a velocity of 100 km/s through the ambient medium. We conclude that the emission is most likely to be associated with the radio PWN of PSR J0855-4644. From the integrated flux density, we estimate the energetics of the PWN.

  20. The Extended X-ray Nebula of PSR J1420-6048

    Energy Technology Data Exchange (ETDEWEB)

    Van Etten, Adam; Romani, Roger W.; /Stanford U., Phys. Dept.

    2011-08-19

    The vicinity of the unidentified EGRET source 3EG J1420-6038 has undergone extensive study in the search for counterparts, revealing the energetic young pulsar PSR J1420-6048 and its surrounding wind nebula as a likely candidate for at least part of the emission from this bright and extended gamma-ray source. We report on new Suzaku observations of PSR J1420-6048, along with analysis of archival XMM Newton data. The low background of Suzaku permits mapping of the extended X-ray nebula, indicating a tail stretching {approx} 8 minutes north of the pulsar. The X-ray data, along with archival radio and VHE data, hint at a pulsar birthsite to the North, and yield insights into its evolution and the properties of the ambient medium. We further explore such properties by modeling the spectral energy distribution (SED) of the extended nebula.

  1. X-RAY STUDIES OF THE BLACK WIDOW PULSAR PSR B1957+20

    International Nuclear Information System (INIS)

    Huang, R. H. H.; Kong, A. K. H.; Takata, J.; Cheng, K. S.; Hui, C. Y.; Lin, L. C. C.

    2012-01-01

    We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase-resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission, which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock are dominated by synchrotron cooling.

  2. Electron-cloud updated simulation results for the PSR, and recent results for the SNS

    International Nuclear Information System (INIS)

    Pivi, M.; Furman, M.A.

    2002-01-01

    Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code

  3. Unbunched beam electron-proton instability in the PSR and advanced hadron facilities

    International Nuclear Information System (INIS)

    Wang, Tai-Sen; Pisent, A.; Neuffer, D.V.

    1989-01-01

    We studied the possibility of the occurrence of transverse instability induced by trapped electrons in unbunched beams in the Proton Storage Ring and the proposed Advance Hadron Facility (AHF) at Los Alamos, as well as in the proposed Kaon Factory at TRIUMF. We found that the e-p instability may be possible for unbunched beams in the PSR but is unlikely to occur in the advanced hadron facilities. 8 refs., 4 figs

  4. THE X-RAY COUNTERPART OF THE HIGH-B PULSAR PSR J0726–2612

    International Nuclear Information System (INIS)

    Speagle, J. S.; Kaplan, D. L.; Van Kerkwijk, M. H.

    2011-01-01

    Middle-aged, cooling neutron stars are observed both as relatively rapidly spinning radio pulsars and as more slowly spinning, strongly magnetized isolated neutron stars (INSs), which stand out by their thermal X-ray spectra. The difference between the two classes may be that the INSs initially had much stronger magnetic fields, which decayed. To test this, we used the Chandra X-ray Observatory to observe 1RXS J072559.8–261229, a possible X-ray counterpart to PSR J0726–2612, which, with its 3.44 s period and 3 × 10 13 G inferred magnetic field strength, is the nearest and least extincted among the possible slowly spinning, strong-field INS progenitors (it likely is in the Gould Belt, at ∼1 kpc). We confirm the identification and find that the pulsar has a spectrum consistent with being purely thermal, with blackbody temperature kT = 87 ± 5 eV and radius R = 5.7 +2.6 –1.3 km at a distance of 1 kpc. We detect sinusoidal pulsations at twice the radio period with a semi-amplitude of 27% ± 5%. The properties of PSR J0726–2612 strongly resemble those of the INSs, except for its much shorter characteristic age of 200 kyr (instead of several Myr). We conclude that PSR J0726–2612 is indeed an example of a young INS, one that started with a magnetic field strength on the low end of those inferred for the INSs, and that, therefore, decayed by a relatively small amount. Our results suggest that the long-period, strong-field pulsars and the INSs are members of the same class, and open up new opportunities to understand the puzzling X-ray and optical emission of the INSs through radio observations of PSR J0726–2612.

  5. THE X-RAY COUNTERPART OF THE HIGH-B PULSAR PSR J0726-2612

    Energy Technology Data Exchange (ETDEWEB)

    Speagle, J. S.; Kaplan, D. L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Van Kerkwijk, M. H., E-mail: kaplan@uwm.edu, E-mail: joshuaspeagle@college.harvard.edu, E-mail: mhvk@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

    2011-12-20

    Middle-aged, cooling neutron stars are observed both as relatively rapidly spinning radio pulsars and as more slowly spinning, strongly magnetized isolated neutron stars (INSs), which stand out by their thermal X-ray spectra. The difference between the two classes may be that the INSs initially had much stronger magnetic fields, which decayed. To test this, we used the Chandra X-ray Observatory to observe 1RXS J072559.8-261229, a possible X-ray counterpart to PSR J0726-2612, which, with its 3.44 s period and 3 Multiplication-Sign 10{sup 13} G inferred magnetic field strength, is the nearest and least extincted among the possible slowly spinning, strong-field INS progenitors (it likely is in the Gould Belt, at {approx}1 kpc). We confirm the identification and find that the pulsar has a spectrum consistent with being purely thermal, with blackbody temperature kT = 87 {+-} 5 eV and radius R = 5.7{sup +2.6}{sub -1.3} km at a distance of 1 kpc. We detect sinusoidal pulsations at twice the radio period with a semi-amplitude of 27% {+-} 5%. The properties of PSR J0726-2612 strongly resemble those of the INSs, except for its much shorter characteristic age of 200 kyr (instead of several Myr). We conclude that PSR J0726-2612 is indeed an example of a young INS, one that started with a magnetic field strength on the low end of those inferred for the INSs, and that, therefore, decayed by a relatively small amount. Our results suggest that the long-period, strong-field pulsars and the INSs are members of the same class, and open up new opportunities to understand the puzzling X-ray and optical emission of the INSs through radio observations of PSR J0726-2612.

  6. A CANDIDATE OPTICAL COUNTERPART TO THE MIDDLE AGED γ -RAY PULSAR PSR J1741–2054

    Energy Technology Data Exchange (ETDEWEB)

    Mignani, R. P.; Marelli, M.; Luca, A. De; Salvetti, D.; Belfiore, A. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133, Milano (Italy); Testa, V. [INAF—Osservatorio Astronomico di Roma, via Frascati 33, I-00040, Monteporzio (Italy); Pierbattista, M. [Department of Astrophysics and Theory of Gravity, Maria Curie-Sklodowska University, ul. Radziszewskiego 10, 20-031 Lublin (Poland); Razzano, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Shearer, A.; Moran, P. [Centre for Astronomy, National University of Ireland, Newcastle Road, Galway (Ireland)

    2016-07-10

    We carried out deep optical observations of the middle aged γ -ray pulsar PSR J1741−2054 with the Very Large Telescope (VLT). We identified two objects, of magnitudes m {sub v} = 23.10 ± 0.05 and m {sub v} = 25.32 ± 0.08, at positions consistent with the very accurate Chandra coordinates of the pulsar, the faintest of which is more likely to be its counterpart. From the VLT images we also detected the known bow-shock nebula around PSR J1741−2054. The nebula is displaced by ∼0.″9 (at the 3 σ confidence level) with respect to its position measured in archival data, showing that the shock propagates in the interstellar medium consistently with the pulsar proper motion. Finally, we could not find evidence of large-scale extended optical emission associated with the pulsar wind nebula detected by Chandra , down to a surface brightness limit of ∼28.1 mag arcsec{sup −2}. Future observations are needed to confirm the optical identification of PSR J1741−2054 and characterize the spectrum of its counterpart.

  7. Detection of long nulls in PSR B1706-16, a pulsar with large timing irregularities

    Science.gov (United States)

    Naidu, Arun; Joshi, Bhal Chandra; Manoharan, P. K.; Krishnakumar, M. A.

    2018-04-01

    Single pulse observations, characterizing in detail, the nulling behaviour of PSR B1706-16 are being reported for the first time in this paper. Our regular long duration monitoring of this pulsar reveals long nulls of 2-5 h with an overall nulling fraction of 31 ± 2 per cent. The pulsar shows two distinct phases of emission. It is usually in an active phase, characterized by pulsations interspersed with shorter nulls, with a nulling fraction of about 15 per cent, but it also rarely switches to an inactive phase, consisting of long nulls. The nulls in this pulsar are concurrent between 326.5 and 610 MHz. Profile mode changes accompanied by changes in fluctuation properties are seen in this pulsar, which switches from mode A before a null to mode B after the null. The distribution of null durations in this pulsar is bimodal. With its occasional long nulls, PSR B1706-16 joins the small group of intermediate nullers, which lie between the classical nullers and the intermittent pulsars. Similar to other intermediate nullers, PSR B1706-16 shows high timing noise, which could be due to its rare long nulls if one assumes that the slowdown rate during such nulls is different from that during the bursts.

  8. Observaciones en la banda de radio de los alrededores de PSR J1646-4346 y PSR J1709-4428

    Science.gov (United States)

    Giacani, E.; Vieytes, M.

    It is generally accepted that most of the rotational energy loss of pulsars appears in the form of a relativistic wind of electron-positron pairs. Under certain conditions, the interaction between this wind and its surroundings is observable in the form of a pulsar wind nebula (PWN). At radio wavelenghts, there are at least two morphological types of PWN, depending on the source of confinement for the wind, but all of them present two unmistakable properties: a) high degree of polarization (>5%) and b) flat radio spectral index (0.0 pulsar. We report on VLA high resolution observations of a region around the pulsars PSR J1645-4346 and PSR J1709-4428 at 1.4, 4.8 and 8.4 GHz. The pulsars appear surrounded by a synchrotron nebula. We argue on the basis of morphology, spectral index and polarization propierties that they are the synchrotron nebulae produced by the spin-down energy of the pulsar.

  9. Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC)

    Science.gov (United States)

    Kim, Eun-Ah; Masue-Slowey, Yoko; Fendorf, Scott; Luthy, Richard G.

    2011-01-01

    The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-x-ray fluorescence (μ-XRF) imaging techniques and mathematical modeling. The μ-XRF results revealed that mercury was concentrated at 0~100 μm from the exterior of the particle after three months of treatment with PSR-AC in 10 ppm HgCl2 aqueous solution. The μ-X-ray absorption near edge spectroscopic (μ-XANES) analyses indicated HgS as a major mercury species, and suggested that the intra-particle mercury transport involved a chemical reaction with PSR polymer. An intra-particle mass transfer model was developed based on either a Langmuir sorption isotherm with liquid phase diffusion (Langmuir model) or a kinetic sorption with surface diffusion (kinetic sorption model). The Langmuir model predicted the general trend of mercury diffusion, although at a slower rate than observed from the μ-XRF map. A kinetic sorption model suggested faster mercury transport, which overestimated the movement of mercuric ions through an exchange reaction between the fast and slow reaction sites. Both μ-XRF and mathematical modeling results suggest mercury removal occurs not only at the outer surface of the PSR-AC particle but also at some interior regions due to a large PSR surface area within an AC particle. PMID:22133913

  10. Swift , XMM - Newton , and NuSTAR Observations of PSR J2032+4127/MT91 213

    Energy Technology Data Exchange (ETDEWEB)

    Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Kong, A. K. H. [Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Tam, P. H. T. [School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082 (China); Hou, X. [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216 (China); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology (China); Hui, C. Y., E-mail: liliray@pa.msu.edu [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

    2017-07-10

    We report our recent Swift , NuSTAR , and XMM - Newton X-ray and Lijiang optical observations on PSR J2032+4127/MT91 213, the γ -ray binary candidate with a period of 45–50 years. The coming periastron of the system was predicted to be in 2017 November, around which high-energy flares from keV to TeV are expected. Recent studies with Chandra and Swift X-ray observations taken in 2015/2016 showed that its X-ray emission has been brighter by a factors of ∼10 than that before 2013, probably revealing some ongoing activities between the pulsar wind and the stellar wind. Our new Swift /XRT lightcurve shows no strong evidence of a single vigorous brightening trend, but rather several strong X-ray flares on weekly to monthly timescales with a slowly brightening baseline, namely the low state. The NuSTAR and XMM - Newton observations taken during the flaring and the low states, respectively, show a denser environment and a softer power-law index during the flaring state, implying that the pulsar wind interacted with the stronger stellar winds of the companion to produce the flares. These precursors would be crucial in studying the predicted giant outburst from this extreme γ -ray binary during the periastron passage in late 2017.

  11. Soft X-ray emission from the radio pulsar PSR 0656 + 14

    Science.gov (United States)

    Cordova, F. A.; Middleditch, J.; Hjellming, R. M.; Mason, K. O.

    1989-01-01

    A radio source with a flux density of a few mJy was found in the error region of the soft X-ray source E0656 + 14, and identified as the radio pulsar PSR 0656 + 14. The radio source has a steep, nonthermal spectrum and a high degree of linear (62 percent) and circular (19 percent) polarization. The X-ray spectrum of the pulsar is among the softest sources observed with the Einstein Observatory. The X-ray data taken with the Einstein imaging proportional counter (IPC) permit a range of blackbody temperatures of 3-6 x 10 to the 5th K, and an equivalent column density of hydrogen smaller than 4 x 10 to the 20th/sq cm. If the assumption is made that the X-ray flux is thermal radiation from surface of the neutron star, then the pulsar must be at a distance smaller than 550 pc, consistent with the low dispersion measure of PSR 0656 + 14. The X-ray timing data suggest that the X-ray emission is modulated at the pulsar's 0.385-s spin period with an amplitude of 18 percent + or - 6 percent, and that there is a 0.0002 probability that this is spurious. It was noted that PSR 0656 + 14 is close to the geometric center of a 20-deg diameter soft X-ray emitting ring called the Gemini-Monoceros enhancement. The close distance of the pulsar, together with its relatively young age of 1.1 x 10 to the 5th yr, makes it possible that the ring is a supernova remnant from the explosion of the pulsar's progenitor. A radio source extending over a region 1.2 to 3.3 arcmin south of the pulsar is a candidate for association with the pulsar.

  12. Soft X-ray emission from the radio pulsar PSR 0656 + 14

    International Nuclear Information System (INIS)

    Cordova, F.A.; Middleditch, J.; Hjellming, R.M.; Mason, K.O.

    1989-01-01

    A radio source with a flux density of a few mJy was found in the error region of the soft X-ray source E0656 + 14, and identified as the radio pulsar PSR 0656 + 14. The radio source has a steep, nonthermal spectrum and a high degree of linear (62%) and circular (19%) polarization. The X-ray spectrum of the pulsar is among the softest sources observed with the Einstein Observatory. The X-ray data taken with the Einstein imaging proportional counter (IPC) permit a range of blackbody temperatures of 3-6 x 10 to the 5th K, and an equivalent column density of hydrogen smaller than 4 x 10 to the 20th/sq cm. If the assumption is made that the X-ray flux is thermal radiation from surface of the neutron star, then the pulsar must be at a distance smaller than 550 pc, consistent with the low dispersion measure of PSR 0656 + 14. The X-ray timing data suggest that the X-ray emission is modulated at the pulsar's 0.385-s spin period with an amplitude of 18% + or - 6%, and that there is a 0.0002 probability that this is spurious. It was noted that PSR 0656 + 14 is close to the geometric center of a 20-deg diameter soft X-ray emitting ring called the Gemini-Monoceros enhancement. The close distance of the pulsar, together with its relatively young age of 1.1 x 10 to the 5th yr, makes it possible that the ring is a supernova remnant from the explosion of the pulsar's progenitor. A radio source extending over a region 1.2 to 3.3 arcmin south of the pulsar is a candidate for association with the pulsar. 46 refs

  13. Selecting and Hiring Psychologically Fit Probation Officers: A Focused Examination of the PEPQ / PSR Plus

    Directory of Open Access Journals (Sweden)

    Don Scott Herrmann

    2014-06-01

    Full Text Available Selecting and hiring the most psychologically fit probation officers is of utmost importance to the judiciary, court administration and the public good.  This study examined the predictive validity of the PsychEval Personality Questionnaire / Protective Service Report Plus (PEPQ / PSR Plus in its ability to predict job performance in a combined cohort of preemployment and incumbent probation officer candidates.  Analyses revealed a statistically significant ability to predict performance problems, demonstrating that the PEPQ / PRS Plus is a valid and clinically useful psychological screening tool for the assessment and selection of probation officer candidates.

  14. Monitoring PSR B1509–58 with RXTE: Spectral analysis 1996–2010

    Directory of Open Access Journals (Sweden)

    E. Litzinger

    2011-01-01

    Full Text Available We present an analysis of the X-ray spectra of the young, Crab-like pulsar PSR B1509–58 (pulse period P ~ 151ms observed by RXTE over 14 years since the beginning of the mission in 1996. The uniform dataset is especially well suited for studying the stability of the spectral parameters over time as well as for determining pulse phase resolved spectral parameters with high significance. The phase averaged spectra as well as the resolved spectra can be well described by an absorbed power law.

  15. Mitigation of the electron-cloud effect in the PSR and SNS protonstorage rings by tailoring the bunch profile

    CERN Document Server

    Pivi, M T

    2003-01-01

    For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure.

  16. MITIGATION OF THE ELECTRON-CLOUD EFFECT IN THE PSR AND SNS PROTONSTORAGE RINGS BY TAILORING THE BUNCH PROFILE

    International Nuclear Information System (INIS)

    Pivi, Mauro T F

    2003-01-01

    For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

  17. Mitigation of the electron-cloud effect in the PSR and SNS proton storage rings by tailoring the bunch profile

    International Nuclear Information System (INIS)

    Pivi, M.; Furman, M.A.

    2003-01-01

    For the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electroncloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

  18. Spin-down Evolution and Radio Disappearance of the Magnetar PSR J1622–4950

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, P. [National Research Council of Canada, Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, P. O. Box 248, Penticton, BC V2A 6J9 (Canada); Camilo, F. [SKA South Africa, Pinelands, 7405 (South Africa); Sarkissian, J. [CSIRO Parkes Observatory, Parkes, NSW 2870 (Australia); Reynolds, J. E.; Johnston, S. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia); Levin, L.; Kramer, M. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Bailes, M. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail H30, P. O. Box 218, Hawthorn, VIC 3122 (Australia); Burgay, M.; Possenti, A., E-mail: paul.scholz@nrc-cnrc.gc.ca [INAF—Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (Italy)

    2017-06-01

    We report on 2.4 yr of radio timing measurements of the magnetar PSR J1622−4950 using the Parkes Observatory, between 2011 November and 2014 March. During this period the torque on the neutron star (inferred from the rotational frequency derivative) varied greatly, though much less erratically than during the 2 yr following its discovery in 2009. During the last year of our measurements the frequency derivative decreased in magnitude monotonically by 20%, to a value of −1.3 × 10{sup −13} s{sup −2}, a factor of 8 smaller than when it was discovered. The flux density continued to vary greatly during our monitoring through 2014 March, reaching a relatively steady low level after late 2012. The pulse profile varied secularly on a similar timescale as the flux density and torque. A relatively rapid transition in all three properties was evident in early 2013. After PSR J1622−4950 was detected in all of our 87 observations up to 2014 March, we did not detect the magnetar in our resumed monitoring starting in 2015 January and have not detected it in any of the 30 observations conducted through 2016 September.

  19. THE TALE OF THE TWO TAILS OF THE OLDISH PSR J2055+2539

    Energy Technology Data Exchange (ETDEWEB)

    Marelli, Martino; Pizzocaro, Daniele; Luca, Andrea De; Gastaldello, Fabio; Caraveo, Patrizia [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy); Parkinson, Pablo Saz [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2016-03-01

    We analyzed a deep XMM-Newton observation of the radio-quiet γ-ray PSR J2055+2539. The spectrum of the X-ray counterpart is nonthermal, with a photon index of Γ = 2.36 ± 0.14 (1σ confidence). We detected X-ray pulsations with a pulsed fraction of 25% ± 3% and a sinusoidal shape. Taking into account considerations on the γ-ray efficiency of the pulsar and on its X-ray spectrum, we can infer a pulsar distance ranging from 450 to 750 pc. We found two different nebular features associated with PSR J2055+2539 and protruding from it. The angle between the two nebular main axes is ∼162.°8 ± 0.°7. The main, brighter feature is 12′ long and <20″ thick, characterized by an asymmetry with respect to the main axis that evolves with the distance from the pulsar, possibly forming a helical pattern. The secondary feature is 250″ × 30″. Both nebulae present an almost flat brightness profile with a sudden decrease at the end. The nebulae can be fitted by either a power-law model or a thermal bremsstrahlung model. A plausible interpretation of the brighter nebula is in terms of a collimated ballistic jet. The secondary nebula is most likely a classical synchrotron-emitting tail.

  20. MODELING MULTI-WAVELENGTH PULSE PROFILES OF THE MILLISECOND PULSAR PSR B1821–24

    Energy Technology Data Exchange (ETDEWEB)

    Du, Yuanjie; Shuai, Ping; Bei, Xiaomin; Chen, Shaolong; Fu, Linzhong; Huang, Liangwei; Lin, Qingqing; Meng, Jing; Wu, Yaojun; Zhang, Hengbin; Zhang, Qian; Zhang, Xinyuan [Qian Xuesen Laboratory of Space Technology, NO. 104, Youyi Road, Haidian District, Beijing 100094 (China); Qiao, Guojun, E-mail: dyj@nao.cas.cn [School of Physics, Peking University, Beijing 100871 (China)

    2015-03-10

    PSR B1821–24 is a solitary millisecond pulsar that radiates multi-wavelength pulsed photons. It has complex radio, X-ray, and γ-ray pulse profiles with distinct peak phase separations that challenge the traditional caustic emission models. Using the single-pole annular gap model with a suitable magnetic inclination angle (α = 40°) and viewing angle (ζ = 75°), we managed to reproduce its pulse profiles of three wavebands. It is found that the middle radio peak originated from the core gap region at high altitudes, and the other two radio peaks originated from the annular gap region at relatively low altitudes. Two peaks of both X-ray and γ-ray wavebands basically originated from the annular gap region, while the γ-ray emission generated from the core gap region contributes somewhat to the first γ-ray peak. Precisely reproducing the multi-wavelength pulse profiles of PSR B1821–24 enables us to understand emission regions of distinct wavebands and justify pulsar emission models.

  1. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF PSR J1836+5925

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Belfiore, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Brigida, M.

    2010-01-01

    The discovery of the γ-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 0 off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 x 10 34 erg s -1 , and a large off-peak (OP) emission component, making it quite unusual among the known γ-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.

  2. Rossi X-Ray Timing Explorer Observation of PSR B0656+14

    International Nuclear Information System (INIS)

    Chang, H.; Ho, C.

    1999-01-01

    PSR B0656+14 was observed by the Rossi X-Ray Timing Explorer (RXTE) with the proportional counter array (PCA) and the high-energy X-ray timing experiment (HEXTE) for 160 ks during 1997 August 22 - September 3. No pulsation was firmly found in the timing analysis, during which the contemporaneous radio ephemeris and various statistical tests were applied in searching for evidence of pulsation. A marginal detection of pulsation at a confidence level of 95.5% based on the H test was found with data in the whole HEXTE energy band. In the energy band of 2-10 keV the RXTE PCA upper limits are about 1 order of magnitude lower than that from ASCA GIS data. If the Compton Gamma Ray Observatory EGRET detection of this pulsar is real, considering the common trait that most EGRET-detected pulsars have a cooling spectrum in hard X-ray and gamma-ray energy bands, the estimated RXTE upper limits indicate a deviation (low-energy turnover) from a cooling spectrum starting from 20 keV or higher. This in turn suggests an outer magnetospheric synchrotron radiation origin for high-energy emissions from PSR B0656+14. The RXTE PCA upper limits also suggest that a reported power-law component based on ASCA SIS data in 1-10 keV fitted jointly with ROSAT data, if real, should be mainly unpulsed. copyright copyright 1999. The American Astronomical Society

  3. Multifrequency behaviour of the anomalous events of PSR J0922+0638

    Science.gov (United States)

    Shaifullah, G.; Tiburzi, C.; Osłowski, S.; Verbiest, J. P. W.; Szary, A.; Künsemöller, J.; Horneffer, A.; Anderson, J.; Kramer, M.; Schwarz, D. J.; Mann, G.; Steinmetz, M.; Vocks, C.

    2018-06-01

    PSR J0922+0638 (B0919+06) shows unexplained anomalous variations in the on-pulse phase, where the pulse appears to episodically move to an earlier longitude for a few tens of rotations before reverting to the usual phase for approximately several hundred to more than a thousand rotations. These events, where the pulse moves in phase by up to 5°, have been previously detected in observations from ˜300 to 2000 MHz. We present simultaneous observations from the Effelsberg 100-m radio telescope at 1350 MHz and the Bornim (Potsdam) station of the LOw Frequency ARray at 150 MHz. Our observations present the first evidence for an absence of the anomalous phase-shifting behaviour at 150 MHz. Instead, the observed intensity at the usual pulse-phase typically decreases, often showing a pseudo-nulling feature corresponding to the times when phase shifts are observed at 1350 MHz. The presence of weak emission at the usual pulse-phase supports the theory that these shifts may result from processes similar to the `profile-absorption' expected to operate for PSR J0814+7429 (B0809+74). A possible mechanism for this could be intrinsic variations of the emission within the pulsar's beam combined with absorption by expanding shells of electrons in the line of sight.

  4. Are Gravitational Waves Spinning Down PSR J1023+0038?

    Science.gov (United States)

    Haskell, B; Patruno, A

    2017-10-20

    The pulsar J1023+0038 rotates with a frequency ν≈592  Hz and has been observed to transition between a radio state, during which it is visible as a millisecond radio pulsar, and a low-mass x-ray binary (LMXB) state, during which accretion powered x-ray pulsations are visible. Timing during the two phases reveals that during the LMXB phase the neutron star is spinning down at a rate of ν[over ˙]≈-3×10^{-15}  Hz/s, which is approximately 27% faster than the rate measured during the radio phase, ν[over ˙]≈-2.4×10^{-15}  Hz/s, and is at odds with the predictions of accretion models. We suggest that the increase in spin-down rate is compatible with gravitational wave emission, particularly with the creation of a "mountain" during the accretion phase. We show that asymmetries in pycnonuclear reaction rates in the crust can lead to a large enough mass quadrupole to explain the observed spin-down rate, which thus far has no other self-consistent explanation. We also suggest two observational tests of this scenario, involving radio timing at the onset of the next millisecond radio pulsar phase, when the mountain should dissipate, and accurate timing during the next LMXB phase to track the increase in torque as the mountain builds up. Another possibility is that an unstable r mode with an amplitude α≈5×10^{-8} may be present in the system.

  5. MULTI-WAVELENGTH OBSERVATIONS OF THE RADIO MAGNETAR PSR J1622–4950 AND DISCOVERY OF ITS POSSIBLY ASSOCIATED SUPERNOVA REMNANT

    International Nuclear Information System (INIS)

    Anderson, Gemma E.; Gaensler, B. M.; Slane, Patrick O.; Drake, Jeremy J.; Rea, Nanda; Kaplan, David L.; Posselt, Bettina; Levin, Lina; Bailes, Matthew; Ramesh Bhat, N. D.; Johnston, Simon; Burke-Spolaor, Sarah; Murray, Stephen S.; Brogan, Crystal L.; Bates, Samuel; Benjamin, Robert A.; Burgay, Marta; D'Amico, Nichi; Esposito, Paolo; Chakrabarty, Deepto

    2012-01-01

    We present multi-wavelength observations of the radio magnetar PSR J1622-4950 and its environment. Observations of PSR J1622-4950 with Chandra (in 2007 and 2009) and XMM (in 2011) show that the X-ray flux of PSR J1622-4950 has decreased by a factor of ∼50 over 3.7 years, decaying exponentially with a characteristic time of τ = 360 ± 11 days. This behavior identifies PSR J1622-4950 as a possible addition to the small class of transient magnetars. The X-ray decay likely indicates that PSR J1622-4950 is recovering from an X-ray outburst that occurred earlier in 2007, before the 2007 Chandra observations. Observations with the Australia Telescope Compact Array show strong radio variability, including a possible radio flaring event at least one and a half years after the 2007 X-ray outburst that may be a direct result of this X-ray event. Radio observations with the Molonglo Observatory Synthesis Telescope reveal that PSR J1622-4950 is 8' southeast of a diffuse radio arc, G333.9+0.0, which appears non-thermal in nature and which could possibly be a previously undiscovered supernova remnant (SNR). If G333.9+0.0 is an SNR then the estimates of its size and age, combined with the close proximity and reasonable implied velocity of PSR J1622-4950, suggest that these two objects could be physically associated.

  6. The High Time Resolution Universe Pulsar Survey - XIII. PSR J1757-1854, the most accelerated binary pulsar

    Science.gov (United States)

    Cameron, A. D.; Champion, D. J.; Kramer, M.; Bailes, M.; Barr, E. D.; Bassa, C. G.; Bhandari, S.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Eatough, R. P.; Flynn, C. M. L.; Freire, P. C. C.; Jameson, A.; Johnston, S.; Karuppusamy, R.; Keith, M. J.; Levin, L.; Lorimer, D. R.; Lyne, A. G.; McLaughlin, M. A.; Ng, C.; Petroff, E.; Possenti, A.; Ridolfi, A.; Stappers, B. W.; van Straten, W.; Tauris, T. M.; Tiburzi, C.; Wex, N.

    2018-03-01

    We report the discovery of PSR J1757-1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit with a neutron star (NS) companion. PSR J1757-1854 exhibits some of the most extreme relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian parameters, yielding the two component masses (mp = 1.3384(9) M⊙ and mc = 1.3946(9) M⊙) plus three tests of general relativity, which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757-1854. With simulations suggesting 3-σ measurements of both the contribution of Lense-Thirring precession to the rate of change of the semimajor axis and the relativistic deformation of the orbit within ˜7-9 yr, PSR J1757-1854 stands out as a unique laboratory for new tests of gravitational theories.

  7. Chandra and RXTE studies of the X-ray/gamma-ray millisecond pulsar PSR J0218+4232

    NARCIS (Netherlands)

    Kuiper, L.; Hermsen, W.; Stappers, B.W.

    2004-01-01

    We report on high-resolution spatial and timing observations of the millisecond pulsar PSR J0218+4232 performed with the Chandra X-ray Observatory (CXO) and the Rossi X-ray Timing Explorer (RXTE). With these observations we were able to study: (a) the possible spatial extent at X-ray energies of the

  8. Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states

    Science.gov (United States)

    Rivera Sandoval, L. E.; Hernández Santisteban, J. V.; Degenaar, N.; Wijnands, R.; Knigge, C.; Miller, J. M.; Reynolds, M.; Altamirano, D.; van den Berg, M.; Hill, A.

    2018-05-01

    We report mid-UV (MUV) observations taken with Hubble Space Telescope (HST)/WFC3, Swift/UVOT, and GALEX/NUV of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states. Both systems were detected in our images and showed MUV variability. At similar orbital phases, the MUV luminosities of both pulsars are comparable. This suggests that the emission processes involved in both objects are similar. We estimated limits on the mass ratio, companion's temperature, inclination, and distance to XSS J12270-4859 by using a Markov Chain Monte Carlo algorithm to fit published folded optical light curves. Using the resulting parameters, we modelled MUV light curves in our HST filters. The resulting models failed to fit our MUV observations. Fixing the mass ratio of XSS J12270-4859 to the value reported in other studies, we obtained a distance of ˜3.2 kpc. This is larger than the one derived from dispersion measure (˜1.4 kpc). Assuming a uniform prior for the mass ratio, the distance is similar to that from radio measurements. However, it requires an undermassive companion (˜0.01M⊙). We conclude that a direct heating model alone cannot fully explain the observations in optical and MUV. Therefore, an additional radiation source is needed. The source could be an intrabinary shock which contributes to the MUV flux and likely to the optical one as well. During the radio pulsar state, the MUV orbital variations of PSR J1023+0038 detected with GALEX, suggest the presence of an asymmetric intrabinary shock.

  9. Polymerase spiral reaction (PSR): a novel, visual isothermal amplification method for detection of canine parvovirus 2 genomic DNA.

    Science.gov (United States)

    Gupta, Vikas; Chakravarti, Soumendu; Chander, Vishal; Majumder, Saurabh; Bhat, Shabir Ahmad; Gupta, Vivek Kumar; Nandi, Sukdeb

    2017-07-01

    Canine parvovirus-2 (CPV-2), which is ubiquitously distributed worldwide, causes severe and often fatal gastroenteritis in dogs. Accurate, differential and rapid diagnosis of canine parvoviral enteritis remains a challenge for clinicians. A recently developed isothermal amplification technique, polymerase spiral reaction (PSR), was optimized for the first time for a viral pathogen with reference recombinant plasmid standards from different CPV-2 antigenic variants (CPV-2, CPV-2a, CPV-2b and CPV-2c) and subsequently validated using clinical samples. Addition of chromogenic substrate SYBR Green I after the completion of the reaction resulted in bright green fluorescence in positive samples, while negative samples and a no-template control remained orange. These results were further substantiated through visualization of a laddering pattern of the PSR-amplified product in an agarose gel in positive cases and the absence of this pattern in no-template control and negative samples. The PSR assay was found to be highly specific, as it did not react with other putative canine pathogens (canine adenovirus 1 and canine distemper virus). The sensitivity of the newly developed PSR technique was compared with that of conventional PCR, real-time PCR and LAMP, using a serial tenfold dilution of canine parvovirus DNA. The detection limit of PSR was found to be at the femtogram level, which is comparable with that of real-time PCR and LAMP, which are ten times more sensitive than conventional PCR. The assay was validated using 90 clinical samples, of which 54 were found positive, while only 45 samples were positive in conventional PCR. This novel assay, which is fully compliant with the 'ASSURED' concept for disease diagnosis, provides a simple, rapid, specific, sensitive and cost-effective method for diagnosis of canine parvoviral enteritis in veterinary clinics.

  10. Broadband pulsations from PSR B1821–24: Implications for emission models and the pulsar population of M28

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Guillemot, L.; Freire, P. C. C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Kerr, M.; Romani, R. W.; Wood, M. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement, LPCE UMR 6115 CNRS, F-45071 Orléans Cedex 02 (France); Ray, P. S.; Wolff, M. T.; Grove, J. E.; Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Bégin, S. [Département de physique, génie physique et optique, Université Laval, Québec (Canada); Janssen, G. H.; Espinoza, C. M. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Venter, C. [Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, 2520 Potchefstroom (South Africa); Casandjian, J. M. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Stairs, I. H. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Ferrara, E. C.; Harding, A. K., E-mail: tyrel.j.johnson@gmail.com, E-mail: guillemo@mpifr-bonn.mpg.de, E-mail: kerrm@stanford.edu, E-mail: icognard@cnrs-orleans.fr, E-mail: Paul.Ray@nrl.navy.mil [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2013-12-01

    We report a 5.4σ detection of pulsed gamma rays from PSR B1821–24 in the globular cluster M28 using ∼44 months of Fermi Large Area Telescope (LAT) data that have been reprocessed with improved instrument calibration constants. We constructed a phase-coherent ephemeris, with post-fit residual rms of 3 μs, using radio data spanning ∼23.2 yr, enabling measurements of the multi-wavelength light-curve properties of PSR B1821–24 at the milliperiod level. We fold RXTE observations of PSR B1821–24 from 1996 to 2007 and discuss implications on the emission zones. The gamma-ray light curve consists of two peaks separated by 0.41 ± 0.02 in phase, with the first gamma-ray peak lagging behind the first radio peak by 0.05 ± 0.02 in phase, consistent with the phase of giant radio pulses. We observe significant emission in the off-peak interval of PSR B1821–24 with a best-fit LAT position inconsistent with the core of M28. We do not detect significant gamma-ray pulsations at the spin or orbital periods from any other known pulsar in M28, and we place limits on the number of energetic pulsars in the cluster. The derived gamma-ray efficiency, ∼2%, is typical of other gamma-ray pulsars with comparable spin-down power, suggesting that the measured spin-down rate (2.2 × 10{sup 36} erg s{sup –1}) is not appreciably distorted by acceleration in the cluster potential. This confirms PSR B1821–24 as the second very energetic millisecond pulsar in a globular cluster and raises the question of whether these represent a separate class of objects that only form in regions of very high stellar density.

  11. NuSTAR OBSERVATIONS AND BROADBAND SPECTRAL ENERGY DISTRIBUTION MODELING OF THE MILLISECOND PULSAR BINARY PSR J1023+0038

    Energy Technology Data Exchange (ETDEWEB)

    Li, K. L.; Kong, A. K. H.; Tam, P. H. T.; Jin, Ruolan [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Takata, J.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Hui, C. Y., E-mail: lilirayhk@gmail.com, E-mail: akong@phys.nthu.edu.tw, E-mail: takata@hku.hk [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

    2014-12-20

    We report the first hard X-ray (3-79 keV) observations of the millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass X-ray binary (LMXB) state and a rotation-powered MSP state. The NuSTAR observations were taken in both LMXB state and rotation-powered state. The source is clearly seen in both states up to ∼79 keV. During the LMXB state, the 3-79 keV flux is about a factor of 10 higher than in the rotation-powered state. The hard X-rays show clear orbital modulation during the X-ray faint rotation-powered state but the X-ray orbital period is not detected in the X-ray bright LMXB state. In addition, the X-ray spectrum changes from a flat power-law spectrum during the rotation-powered state to a steeper power-law spectrum in the LMXB state. We suggest that the hard X-rays are due to the intrabinary shock from the interaction between the pulsar wind and the injected material from the low-mass companion star. During the rotation-powered MSP state, the X-ray orbital modulation is due to Doppler boosting of the shocked pulsar wind. At the LMXB state, the evaporating matter of the accretion disk due to the gamma-ray irradiation from the pulsar stops almost all the pulsar wind, resulting in the disappearance of the X-ray orbital modulation.

  12. X-Ray Observations of High-Energy Pulsars: PSR B1951+32 and Geminga

    Science.gov (United States)

    Ho, Cheng

    Observations at frequencies across a wide range of electromagnetic spectra are key to the understanding of the origin and mechanisms of high-energy emissions from pulsars. We propose to observe the high-energy pulsars PSR B1951+32 and Geminga with XTE. These two sources emit X-rays at low enough count rate that we can acquire high resolution timing and spectral data, allowing us to perform detailed analysis on the ground. Staring integration of 10 ksec for each source is requested. Data obtained in these observations, together with those from ROSAT, GRO and a planned project for optical counterpart study at Los Alamos, will provide crucial information to advance high-energy pulsar research.

  13. Timing properties of PSR 1951 + 32 in the CTB 80 supernova remnant

    International Nuclear Information System (INIS)

    Foster, R.S.; Backer, D.C.; Wolszczan, A.

    1990-01-01

    Timing observations of PSR 1951+32, the 39.5 ms pulsar found in the CTB 80 supernova remnant, have detected a spin-up in the rotation rate of the neutron star. The fractional change in the rotational frequency of 2.1 x 10 to the -9th was accompanied by a fractional change in the frequency derivative of -0.00019 which has persisted for 1 yr after the event. Updated VLA astrometric observations of the pulsar are presented. Dispersion measure variations have been measured between 430 MHz and 1400 MHz at the level of 0.02 pc/cu cm. Together, dispersion measure fluctuations and diffractive scintillations indicate a power-law electron density turbulence spectrum on scales sizes between 10 to the 9th and 10 to the 14th cm that may be relevant to cosmic-ray propagation. 34 refs

  14. LONG-TERM MONITORING OF MODE SWITCHING FOR PSR B0329+54

    International Nuclear Information System (INIS)

    Chen, J. L.; Wang, N.; Liu, Z. Y.; Yuan, J. P.; Wang, H. G.; Lyne, A.; Jessner, A.; Kramer, M.

    2011-01-01

    The mode-switching phenomenon of PSR B0329+54 is investigated based on the long-term monitoring from 2003 September to 2009 April made with the Urumqi 25 m radio telescope at 1540 MHz. At that frequency, the change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratios between the leading and trailing components are measured for the individual profiles averaged over a few minutes. It is found that the ratios follow normal distributions, where the abnormal mode has a greater typical width than the normal mode, indicating that the abnormal mode is less stable than the normal mode. Our data show that 84.9% of the time for PSR B0329+54 was in the normal mode and 15.1% was in the abnormal mode. From the two passages of eight-day quasi-continuous observations in 2004, supplemented by the daily data observed with the 15 m telescope at 610 MHz at Jodrell Bank Observatory, the intrinsic distributions of mode timescales are constrained with the Bayesian inference method. It is found that the gamma distribution with the shape parameter slightly smaller than 1 is favored over the normal, log-normal, and Pareto distributions. The optimal scale parameters of the gamma distribution are 31.5 minutes for the abnormal mode and 154 minutes for the normal mode. The shape parameters have very similar values, i.e., 0.75 +0.22 – 0 .17 for the normal mode and 0.84 +0.28 – 0 .22 for the abnormal mode, indicating that the physical mechanisms in both modes may be the same. No long-term modulation of the relative intensity ratios was found for either mode, suggesting that the mode switching was stable. The intrinsic timescale distributions, constrained for this pulsar for the first time, provide valuable information to understand the physics of mode switching.

  15. SINGLE-PULSE RADIO OBSERVATIONS OF THE GALACTIC CENTER MAGNETAR PSR J1745–2900

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhen; Shen, Zhi-Qiang; Wu, Ya-Jun; Zhao, Rong-Bing; Fan, Qing-Yuan; Hong, Xiao-Yu; Jiang, Dong-Rong; Li, Bin; Liang, Shi-Guang; Ling, Quan-Bao; Liu, Qing-Hui; Qian, Zhi-Han; Zhang, Xiu-Zhong; Zhong, Wei-Ye; Ye, Shu-Hua [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China); Wu, Xin-Ji [Department of Astronomy, Peking University, Beijing 100871 (China); Manchester, R. N. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Weltevrede, P. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Yuan, Jian-Ping [Key Laboratory of Radio Astronomy, Chinese Academy of Sciences (China); Lee, Ke-Jia, E-mail: yanzhen@shao.ac.cn [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

    2015-11-20

    In this paper, we report radio observations of the Galactic Center magnetar PSR J1745–2900 at six epochs between 2014 June and October. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745–2900 show dramatic changes from epoch to epoch, showing that the pulsar was in its “erratic” phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was 10 times larger than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow “spiky” pulses that follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux densities are 10 times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses were between 0.°2 and 0.°9, much narrower than that of the integrated profile (∼12°). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of observation, showing the same properties as those detected in MJD 56836. These strong spiky pulses cannot be classified as “giant” pulses but are more closely related to normal pulse emission.

  16. Prospects of Constraining the Dense Matter Equation of State from Timing Analysis of Pulsars in Double Neutron Star Binaries: The Cases of PSR J0737 ‒ 3039A and PSR J1757 ‒ 1854

    Directory of Open Access Journals (Sweden)

    Manjari Bagchi

    2018-02-01

    Full Text Available The Lense-Thirring effect from spinning neutron stars in double neutron star binaries contributes to the periastron advance of the orbit. This extra term involves the moment of inertia of the neutron stars. The moment of inertia, on the other hand, depends on the mass and spin of the neutron star, as well as the equation of state of the matter. If at least one member of the double neutron star binary (better the faster one is a radio pulsar, then accurate timing analysis might lead to the estimation of the contribution of the Lense-Thirring effect to the periastron advance, which will lead to the measurement of the moment of inertia of the pulsar. The combination of the knowledge on the values of the moment of inertia, the mass and the spin of the pulsar will give a new constraint on the equation of state. Pulsars in double neutron star binaries are the best for this purpose as short orbits and moderately high eccentricities make the Lense-Thirring effect substantial, whereas tidal effects are negligible (unlike pulsars with main sequence or white-dwarf binaries. The most promising pulsars are PSR J0737 − 3039A and PSR J1757 − 1854. The spin-precession of pulsars due to the misalignment between the spin and the orbital angular momentum vectors affect the contribution of the Lense-Thirring effect to the periastron advance. This effect has been explored for both PSR J0737 − 3039A and PSR J1757 − 1854, and as the misalignment angles for both of these pulsars are small, the variation in the Lense-Thirring term is not much. However, to extract the Lense-Thirring effect from the observed rate of the periastron advance, more accurate timing solutions including precise proper motion and distance measurements are essential.

  17. DO RADIO MAGNETARS PSR J1550-5418 AND J1622-4950 HAVE GIGAHERTZ-PEAKED SPECTRA?

    Energy Technology Data Exchange (ETDEWEB)

    Kijak, J.; Tarczewski, L.; Lewandowski, W. [Kepler Institute of Astronomy, University of Zielona Gora, Lubuska 2, 65-265 Zielona Gora (Poland); Melikidze, G., E-mail: jkijak@astro.ia.uz.zgora.pl [Also at Abastumani Astrophysical Observatory, Ilia State University, 3-5 Cholokashvili Avenue, Tbilisi 0160, Georgia. (Georgia)

    2013-07-20

    We study the radio spectra of two magnetars, PSR J1550-5418 and J1622-4950. We argue that they are good candidates for pulsars with gigahertz-peaked spectra (GPS), as their observed flux density decreases at frequencies below 7 GHz. We suggest that this behavior is due to the influence of the pulsars' environments on radio waves. Both of the magnetars are associated with supernova remnants and thus are surrounded by hot, ionized gas, which can be responsible for the free-free absorption of radio waves. We conclude that the GPS feature of both magnetars and typical pulsars are formed by similar processes in the surrounding media rather than by different radio-emission mechanisms. Thus, the radio magnetars PSR J1550-5418 and J1622-4950 can be included in the class of GPS pulsars.

  18. The Association of PSR B1757-24 and the SNR G5.4-1.2

    Science.gov (United States)

    Gvaramadze, V. V.

    The association of PSR B1757-24 and the supernova remnant (SNR) G5.4-1.2 was recently questioned by Thorsett et al. (2002) on the basis of proper motion measurements of the pulsar and the "incorrect" orientation of the vector of pulsar transverse velocity (inferred from the orientation of the cometary-shaped pulsar wind nebula). We show, however, that the association could be real if both objects are the remnants of an off-centered cavity supernova explosion.

  19. A preliminary comparative study of the electron-cloud effect for the PSR, ISIS, and the ESS

    International Nuclear Information System (INIS)

    Furman, M.A.; Pivi, M.T.F.

    2003-01-01

    We present preliminary electron-cloud simulation results for the Proton Storage Ring (PSR) at LANL, ISIS at RAL, and the European Spallation Source (ESS). For each storage ring, we simulate the build-up and dissipation of the electron cloud (EC) in a representative field-free section of the vacuum chamber. For all three cases, we choose the same residual gas temperature, secondary emission yield (SEY), and secondary emission spectrum. Other variables such as proton loss rate, bunch profile, intensity and energy, residual gas pressure and chamber geometry, are set at the corresponding values for each machine. Under these assumptions, we conclude that, of the three machines, the PSR is the most severely affected by the electron cloud effect (ECE), followed by the ESS, with ISIS a distant third. We illustrate a strong sensitivity of the ECE to the longitudinal bunch profile by choosing two different shapes for the case of the PSR, and a weak sensitivity to residual gas pressure. This preliminary study does not address the ECE in other regions of the machine, nor the beam instability that might arise from the EC

  20. Optical Observations of Psr J2021+3651 in the Dragonfly Nebula With the GTC

    Science.gov (United States)

    Kirichenko, Aida; Danilenko, Andrey; Shternin, Peter; Shibanov, Yuriy; Ryspaeva, Elizaveta; Zyuzin, Dima; Durant, Martin; Kargaltsev, Oleg; Pavlov, George; Cabrera-Lavers, Antonio

    2015-03-01

    PSR J2021+3651 is a 17 kyr old rotation powered pulsar detected in the radio, X-rays, and γ-rays. It powers a torus-like pulsar wind nebula with jets, dubbed the Dragonfly, which is very similar to that of the Vela pulsar. The Dragonfly is likely associated with the extended TeV source VER J2019+368 and extended radio emission. We conducted first deep optical observations with the Gran Telescopio Canarias in the Sloan r‧ band to search for optical counterparts of the pulsar and its nebula. No counterparts were detected down to r‧ ≳ 27.2 and ≳24.8 for the point-like pulsar and the compact X-ray nebula, respectively. We also reanalyzed Chandra archival X-ray data taking into account an interstellar extinction-distance relation, constructed by us for the Dragonfly line of sight using the red-clump stars as standard candles. This allowed us to constrain the distance to the pulsar, D=1.8-1.4+1.7 kpc at 90% confidence. It is much smaller than the dispersion measure distance of ˜12 kpc but compatible with a γ-ray “pseudo-distance” of 1 kpc. Based on that and the optical upper limits, we conclude that PSR J2021+3651, similar to the Vela pulsar, is a very inefficient nonthermal emitter in the optical and X-rays, while its γ-ray efficiency is consistent with an average efficiency for γ-pulsars of similar age. Our optical flux upper limit for the pulsar is consistent with the long-wavelength extrapolation of its X-ray spectrum while the nebula flux upper limit does not constrain the respective extrapolation. Based on observations made with the Gran Telescopio Canarias (GTC), instaled in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias, in the island of La Palma, programme GTC3-11B.

  1. THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

    Energy Technology Data Exchange (ETDEWEB)

    Weisskopf, Martin C.; Elsner, Ronald F.; O' Dell, Stephen L.; Tennant, Allyn F. [NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Romani, Roger W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Razzano, Massimiliano [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael [Santa Cruz Institute for Particle Physics, Department of Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Ray, Paul S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kerr, Matthew [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States); Harding, Alice [Astrophysics Science Division, NASA Goddard Space Flight Center, Code 663, Greenbelt, MD 20771 (United States); Swartz, Douglas A. [Universities Space Research Association, NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Carraminana, Alberto [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, Puebla 72840 (Mexico); Becker, Werner; Kanbach, Gottfried [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching bei Muenchen (Germany); De Luca, Andrea [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Thompson, David J. [Astroparticle Physics Laboratory, NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States)

    2011-12-10

    We report the probable identification of the X-ray counterpart to the {gamma}-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20{sup h}21{sup m}30.{sup s}733, decl. +40 Degree-Sign 26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to {gamma}-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

  2. POST-OUTBURST RADIO OBSERVATIONS OF THE HIGH MAGNETIC FIELD PULSAR PSR J1119-6127

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Walid A.; Pearlman, Aaron B.; Dobreva, Tatyana; Kocz, Jonathon; Prince, Thomas A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Horiuchi, Shinji [CSIRO Astronomy and Space Science, Canberra Deep Space Communications Complex, P.O. Box 1035, Tuggeranong, ACT 2901 (Australia); Lippuner, Jonas [TAPIR, Walter Burke Institute for Theoretical Physics, MC 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)

    2017-01-01

    We have carried out high-frequency radio observations of the high magnetic field pulsar PSR J1119-6127 following its recent X-ray outburst. While initial observations showed no evidence of significant radio emission, subsequent observations detected pulsed emission across a large frequency band. In this Letter, we report on the initial disappearance of the pulsed emission and its prompt reactivation and dramatic evolution over several months of observation. The periodic pulse profile at S -band (2.3 GHz) after reactivation exhibits a multi-component emission structure, while the simultaneous X -band (8.4 GHz) profile shows a single emission peak. Single pulses were also detected at S -band near the main emission peaks. We present measurements of the spectral index across a wide frequency bandwidth, which captures the underlying changes in the radio emission profile of the neutron star. The high-frequency radio detection, unusual emission profile, and observed variability suggest similarities with magnetars, which may independently link the high-energy outbursts to magnetar-like behavior.

  3. X-Ray Study of Variable Gamma-Ray Pulsar PSR J2021+4026

    Science.gov (United States)

    Wang, H. H.; Takata, J.; Hu, C.-P.; Lin, L. C. C.; Zhao, J.

    2018-04-01

    PSR J2021+4026 showed a sudden decrease in the gamma-ray emission at the glitch that occurred around 2011 October 16, and a relaxation of the flux to the pre-glitch state at around 2014 December. We report X-ray analysis results of the data observed by XMM-Newton on 2015 December 20 in the post-relaxation state. To examine any change in the X-ray emission, we compare the properties of the pulse profiles and spectra at the low gamma-ray flux state and at the post-relaxation state. The phase-averaged spectra for both states can be well described by a power-law component plus a blackbody component. The former is dominated by unpulsed emission and probably originated from the pulsar wind nebula as reported by Hui et al. The emission property of the blackbody component is consistent with the emission from the polar cap heated by the back-flow bombardment of the high-energy electrons or positrons that were accelerated in the magnetosphere. We found no significant change in the X-ray emission properties between two states. We suggest that the change of the X-ray luminosity is at an order of ∼4%, which is difficult to measure with the current observations. We model the observed X-ray light curve with the heated polar cap emission, and we speculate that the observed large pulsed fraction is owing to asymmetric magnetospheric structure.

  4. THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

    International Nuclear Information System (INIS)

    Weisskopf, Martin C.; Elsner, Ronald F.; O'Dell, Stephen L.; Tennant, Allyn F.; Romani, Roger W.; Razzano, Massimiliano; Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael; Ray, Paul S.; Kerr, Matthew; Harding, Alice; Swartz, Douglas A.; Carramiñana, Alberto; Becker, Werner; Kanbach, Gottfried; De Luca, Andrea; Thompson, David J.

    2011-01-01

    We report the probable identification of the X-ray counterpart to the γ-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20 h 21 m 30. s 733, decl. +40°26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to γ-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

  5. γ rays of 0.3-30 MeV from PSR0833 - 45

    International Nuclear Information System (INIS)

    Tuemer, O.T.; Long, J.; O'Neill, T.; Zych, A.; White, R.S.

    1984-01-01

    Pulsed γ rays from the Vela pulsar PSR0833-45 are reported for the first time at the medium energies, E, of 0.3-30 MeV. They were observed with the double scatter γ-ray telescope 31 days after a large glitch in the pulsar period. The first and second pulses were detected from single scatters in the top scintillators, S1, at energies > 0.3 MeV, and by double scatters from all detector cell pairs at energies of 1-30 MeV. The phase separation of the two pulses is 0.43 +- 0.02 at the same absolute phases previously found by SAS 2 and COS B for E > 35 MeV. The energy distribution with six points from 0.3 to 30 MeV appears to bend away from the COS B power law at the lower energies and is well below the HEAO 1 upper limits. (author)

  6. Interstellar scintillations of PSR B1919+21: space-ground interferometry

    Science.gov (United States)

    Shishov, V. I.; Smirnova, T. V.; Gwinn, C. R.; Andrianov, A. S.; Popov, M. V.; Rudnitskiy, A. G.; Soglasnov, V. A.

    2017-07-01

    We carried out observations of pulsar PSR B1919+21 at 324 MHz to study the distribution of interstellar plasma in the direction of this pulsar. We used the RadioAstron (RA) space radio telescope, together with two ground telescopes: Westerbork (WB) and Green Bank (GB). The maximum baseline projection for the space-ground interferometer was about 60 000 km. We show that interstellar scintillation of this pulsar consists of two components: diffractive scintillations from inhomogeneities in a layer of turbulent plasma at a distance z1 = 440 pc from the observer or homogeneously distributed scattering material to the pulsar; and weak scintillations from a screen located near the observer at z2 = 0.14 ± 0.05 pc. Furthermore, in the direction to the pulsar we detected a prism that deflects radiation, leading to a shift in observed source position. We show that the influence of the ionosphere can be ignored for the space-ground baseline. Analysis of the spatial coherence function for the space-ground baseline (RA-GB) yielded a scattering angle in the observer plane of θscat = 0.7 mas. An analysis of the time-frequency correlation function for weak scintillations yielded an angle of refraction in the direction to the pulsar θref, 0 = 110 ms and a distance to the prism zprism ≤ 2 pc.

  7. GMRT Galactic Plane Pulsar and Transient Survey and the Discovery of PSR J1838+1523

    Science.gov (United States)

    Surnis, Mayuresh P.; Joshi, Bhal Chandra; McLaughlin, Maura A.; Lorimer, Duncan R.; M A, Krishnakumar; Manoharan, P. K.; Naidu, Arun

    2018-05-01

    We report the results of a blind pulsar survey carried out with the Giant Metrewave Radio Telescope (GMRT) at 325 MHz. The survey covered about 10% of the region between Galactic longitude 45° pulsars. One of these, PSR J1838+1523, was previously unknown and has a period of 549 ms and a dispersion measure of 68 pc cm-3. We also present the timing solution of this pulsar obtained from multi-frequency timing observations carried out with the GMRT and the Ooty Radio Telescope. The measured flux density of this pulsar is 4.3±1.8 and 1.2±0.7 mJy at 325 and 610 MHz, respectively. This implies a spectral index of -2 ±0.8, thus making the expected flux density at 1.4 GHz to be about 0.2 mJy, which would be just detectable in the high frequency pulsar surveys like the Northern High Time Resolution Universe pulsar survey. This discovery underlines the importance of low frequency pulsar surveys in detecting steep spectrum pulsars, thus providing complementary coverage of the pulsar population.

  8. Research on review technology for three key safety factors of periodic safety review (PSR) and its application to Qinshan Nuclear Power Plant

    International Nuclear Information System (INIS)

    Xu Shoulv; Yao Weida; Dou Yikang; Lin Shaoxuan; Cao Yenan; Zhou Quanfu; Zheng Jiong; Zhang Ming

    2009-04-01

    In 2001, after 10 years' operation, Qinshan Nuclear Power Plant (Q1) started to carry out periodic safety review (PSR) based on a nuclear safety guideline, Periodic Safety Review for Operational Nuclear Power Plants (HAF0312), issued by National Nuclear Safety Administration of China (NNSA). Entrusted by the owner of Q1, Shanghai Nuclear Engineering Research and Design Institute (SNERDI) implemented reviews of three key safety factors including safety analysis, equipment qualification and ageing. PSR was a challenging work in China at that time and through three years' research and practice, SNERDI summarized a systematic achievement for the review including review methodology, scoping, review contents and implementation steps, etc.. During the process of review for the three safety factors, totally 148 review reports and 341 recommendations for corrections were submitted to Q1. These reports and recommendations have provided guidance for correction actions as follow-up of PSR. This paper focuses on technical aspects to carry out PSR for the above-mentioned three safety factors, including review scoping, contents, methodology and main steps. The review technology and relevant experience can be taken for reference for other NPPs to carry out PSR. (authors)

  9. Precision Timing of PSR J0437-4715: An Accurate Pulsar Distance, a High Pulsar Mass, and a Limit on the Variation of Newton's Gravitational Constant

    Science.gov (United States)

    Verbiest, J. P. W.; Bailes, M.; van Straten, W.; Hobbs, G. B.; Edwards, R. T.; Manchester, R. N.; Bhat, N. D. R.; Sarkissian, J. M.; Jacoby, B. A.; Kulkarni, S. R.

    2008-05-01

    Analysis of 10 years of high-precision timing data on the millisecond pulsar PSR J0437-4715 has resulted in a model-independent kinematic distance based on an apparent orbital period derivative, dot Pb , determined at the 1.5% level of precision (Dk = 157.0 +/- 2.4 pc), making it one of the most accurate stellar distance estimates published to date. The discrepancy between this measurement and a previously published parallax distance estimate is attributed to errors in the DE200 solar system ephemerides. The precise measurement of dot Pb allows a limit on the variation of Newton's gravitational constant, |Ġ/G| <= 23 × 10-12 yr-1. We also constrain any anomalous acceleration along the line of sight to the pulsar to |a⊙/c| <= 1.5 × 10-18 s-1 at 95% confidence, and derive a pulsar mass, mpsr = 1.76 +/- 0.20 M⊙, one of the highest estimates so far obtained.

  10. Simultaneous broadband observations and high-resolution X-ray spectroscopy of the transitional millisecond pulsar PSR J1023+0038

    Science.gov (United States)

    Coti Zelati, F.; Campana, S.; Braito, V.; Baglio, M. C.; D'Avanzo, P.; Rea, N.; Torres, D. F.

    2018-03-01

    We report on the first simultaneous XMM-Newton, NuSTAR, and Swift observations of the transitional millisecond pulsar PSR J1023+0038 in the X-ray active state. Our multi-wavelength campaign allowed us to investigate with unprecedented detail possible spectral variability over a broad energy range in the X-rays, as well as correlations and lags among emissions in different bands. The soft and hard X-ray emissions are significantly correlated, with no lags between the two bands. On the other hand, the X-ray emission does not correlate with the UV emission. We refine our model for the observed mode switching in terms of rapid transitions between a weak propeller regime and a rotation-powered radio pulsar state, and report on a detailed high-resolution X-ray spectroscopy using all XMM-Newton Reflection Grating Spectrometer data acquired since 2013. We discuss our results in the context of the recent discoveries on the system and of the state of the art simulations on transitional millisecond pulsars, and show how the properties of the narrow emission lines in the soft X-ray spectrum are consistent with an origin within the accretion disc.

  11. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF GAMMA-RAY PULSARS PSR J1057-5226, J1709-4429, AND J1952+3252

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ajello, M.; Bechtol, K.; Berenji, B.; Borgland, A. W.; Bouvier, A.; Buehler, R.; Antolini, E.; Bonamente, E.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Brigida, M.; Bruel, P.; Burnett, T. H.

    2010-01-01

    The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057-5226, PSR J1709-4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed emission from these pulsars for the first time and provide a more complete picture of the emission mechanism. The results confirm some, but not all, of the features seen in the EGRET data.

  12. Old but Still Warm: Far-UV Detection of PSR B0950+08

    Science.gov (United States)

    Pavlov, G. G.; Rangelov, B.; Kargaltsev, O.; Reisenegger, A.; Guillot, S.; Reyes, C.

    2017-11-01

    We report on a Hubble Space Telescope detection of the nearby, old pulsar B0950+08 (d≃ 262 pc, spin-down age 17.5 Myr) in two far-ultraviolet (FUV) bands. We measured the mean flux densities {\\bar{f}}ν =109+/- 6 nJy and 83 ± 14 nJy in the F125LP and F140LP filters (pivot wavelengths 1438 and 1528 Å). Using the FUV data together with previously obtained optical-UV data, we conclude that the optical-FUV spectrum consists of two components—a nonthermal (presumably magnetospheric) power-law spectrum ({f}ν \\propto {ν }α ) with slope α ˜ -1.2 and a thermal spectrum emitted from the bulk of the neutron star (NS) surface with a temperature in the range of (1-3) × 105 K, depending on interstellar extinction and NS radius. These temperatures are much higher than predicted by NS cooling models for such an old pulsar, which means that some heating mechanisms operate in NSs. A plausible mechanism responsible for the high temperature of PSR B0950+08 is the interaction of vortex lines of the faster rotating neutron superfluid with the slower rotating normal matter in the inner NS crust (vortex creep heating). Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13783.

  13. LONG-TERM X-RAY MONITORING OF THE YOUNG PULSAR PSR B1509–58

    International Nuclear Information System (INIS)

    Livingstone, Margaret A.; Kaspi, Victoria M.

    2011-01-01

    It has long been thought that the pulsed X-ray properties of rotation-powered pulsars are stable on long timescales. However, long-term, systematic studies of individual sources have been lacking. Furthermore, dramatic X-ray variability has now been observed from two pulsars having inferred sub-critical dipole magnetic fields. Here we present an analysis of the long-term pulsed X-ray properties of the young, energetic pulsar PSR B1509–58 using data from the Rossi X-ray Timing Explorer. We measured the 2-50 keV pulsed flux for 14.7 yr of X-ray observations and found that it is consistent with being constant on all relevant timescales, and place a 3σ upper limit on day-to-week variability of <28%. In addition, we searched for magnetar-like X-ray bursts in all observations and found none, which we use to constrain the measurable burst rate to less than one per 750 ks of observations. We also searched for variability in the pulse profile and found that it is consistent with being stable on timescales of days to decades. This supports the hypothesis that X-ray properties of rotation-powered X-ray pulsars can be stable on decade-long timescales. In addition, we extend the existing timing solution by 7.1 yr to a total of 28.4 yr and report updated values of the braking index, n = 2.832 ± 0.003, and the second braking index, m = 17.6 ± 1.9.

  14. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Atwood, William B.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, Milan; Baughman, B.M.; Bechtol, K.; Bellazzini, Ronaldo; Berenji, Bijan; Bloom, Elliott D.; Bogaert, G.; Borgland, Anders W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.

    2009-01-01

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 ± 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 ± 0.004 ± 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 ± 3 ± 11) x 10 -8 cm -2 s -1 . The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE -# Gamma#e (-E/E c ) where the energy E is expressed in GeV. The photon index is Γ = 1.5 ± 0.1 ± 0.1 and the exponential cut-off is E c = 2.4 ± 0.3 ± 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is -2 but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  15. Serendipitous discovery of an infrared bow shock near PSR J1549–4848 with Spitzer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhongxiang [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Kaplan, David L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Slane, Patrick [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Morrell, Nidia [Las Campanas Observatory, Observatories of the Carnegie Institution of Washington, La Serena (Chile); Kaspi, Victoria M. [Department of Physics, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada)

    2013-06-01

    We report on the discovery of an infrared cometary nebula around PSR J1549–4848 in our Spitzer survey of a few middle-aged radio pulsars. Following the discovery, multi-wavelength imaging and spectroscopic observations of the nebula were carried out. We detected the nebula in Spitzer Infrared Array Camera 8.0, Multiband Imaging Photometer for Spitzer 24 and 70 μm imaging, and in Spitzer IRS 7.5-14.4 μm spectroscopic observations, and also in the Wide-field Infrared Survey Explorer all-sky survey at 12 and 22 μm. These data were analyzed in detail, and we find that the nebula can be described with a standard bow shock shape, and that its spectrum contains polycyclic aromatic hydrocarbon and H{sub 2} emission features. However, it is not certain which object drives the nebula. We analyze the field stars and conclude that none of them can be the associated object because stars with a strong wind or mass ejection that usually produce bow shocks are much brighter than the field stars. The pulsar is approximately 15'' away from the region in which the associated object is expected to be located. In order to resolve the discrepancy, we suggest that a highly collimated wind could be emitted from the pulsar and produce the bow shock. X-ray imaging to detect the interaction of the wind with the ambient medium- and high-spatial resolution radio imaging to determine the proper motion of the pulsar should be carried out, which will help verify the association of the pulsar with the bow shock nebula.

  16. GAMMA-RAY EMISSION FROM PSR J0007+7303 USING SEVEN YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian; Torres, Diego F.; De Oña Wilhelmi, Emma; Rea, Nanda; Martin, Jonatan [Institute of Space Sciences (CSIC–IEEC), Campus UAB, Carrer de Magrans s/n, E-08193 Barcelona (Spain)

    2016-11-01

    Based on more than seven years of Fermi Large Area Telescope Pass 8 data, we report on a detailed analysis of the bright gamma-ray pulsar (PSR) J0007+7303. We confirm that PSR J0007+7303 is significantly detected as a point source also during the off-peak phases with a test statistic value of 262 (∼16 σ ). In the description of the off-peak spectrum of PSR J0007+7303, a power law with an exponential cutoff at 2.7 ± 1.2 ± 1.3 GeV (the first/second uncertainties correspond to statistical/systematic errors) is preferred over a single power law at a level of 3.5 σ . The possible existence of a cutoff hints at a magnetospheric origin of the emission. In addition, no extended gamma-ray emission is detected that is compatible with either the supernova remnant (CTA 1) or the very high-energy (>100 GeV) pulsar wind nebula. A flux upper limit of 6.5 × 10{sup −12} erg cm{sup −2} s{sup −1} in the energy range 10–300 GeV is reported, for an extended source assuming the morphology of the VERITAS detection. During on-peak phases, a sub-exponential cutoff is significantly preferred (∼11 σ ) for representing the spectral energy distribution, in both the phase-averaged and phase-resolved spectra. Three glitches are detected during the observation period and we found no flux variability at the time of the glitches or in the long-term behavior. We also report the discovery of a previously unknown gamma-ray source in the vicinity of PSR J0007+7303, Fermi J0020+7328, which we associate with the z = 1.781 quasar S5 0016+73. A concurrent analysis of this source is needed to correctly characterize the behavior of CTA 1 and it is also presented in the paper.

  17. The NuSTAR view of the non-thermal emission from PSR J0437-4715

    DEFF Research Database (Denmark)

    Guillot, S.; Kaspi, V M; Archibald, Robert F.

    2016-01-01

    We present a hard X-ray Nuclear Spectroscopic Telescope Array (NuSTAR) observation of PSR J0437-4715, the nearest millisecond pulsar. The known pulsations at the apparent pulse period similar to 5.76 ms are observed with a significance of 3.7 sigma, at energies up to 20 keV above which the Nu...... by combining model fits to the pulsar's phase-folded light curve with the pulsar's well-defined mass and distance from radio timing observations....

  18. PULSED VERY HIGH ENERGY γ-RAY EMISSION CONSTRAINTS FOR PSR B1951+32 FROM STACEE OBSERVATIONS

    International Nuclear Information System (INIS)

    Zweerink, J.; Ball, J.; Carson, J. E.; Jarvis, A.; Ong, R. A.; Kildea, J.; Hanna, D. S.; Lindner, T.; Mueller, C.; Ragan, K.; Covault, C. E.; Driscoll, D. D.; Fortin, P.; Mukherjee, R.; Gingrich, D. M.; Williams, D. A.

    2009-01-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground-based telescope that uses the wave-front-sampling technique to detect very high energy (VHE) gamma rays. STACEE's sensitivity in the energy range near 100 GeV permits useful observations of pulsars with the potential to discriminate between various proposed mechanisms for pulsed gamma-ray emission. Based on the 11.3 hr of data taken during the 2005 and 2006 observing seasons, we derive an upper limit on the pulsed gamma-ray emission from PSR B1951+32 of -11 photons cm -2 s -1 above an energy threshold of 117 GeV.

  19. SCINTILLATION ARCS IN LOW-FREQUENCY OBSERVATIONS OF THE TIMING-ARRAY MILLISECOND PULSAR PSR J0437–4715

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, N. D. R.; Ord, S. M.; Tremblay, S. E.; McSweeney, S. J.; Tingay, S. J. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia)

    2016-02-10

    Low-frequency observations of pulsars provide a powerful means for probing the microstructure in the turbulent interstellar medium (ISM). Here we report on high-resolution dynamic spectral analysis of our observations of the timing-array millisecond pulsar PSR J0437–4715 with the Murchison Widefield Array (MWA), enabled by our recently commissioned tied-array beam processing pipeline for voltage data recorded from the high time resolution mode of the MWA. A secondary spectral analysis reveals faint parabolic arcs akin to those seen in high-frequency observations of pulsars with the Green Bank and Arecibo telescopes. Data from Parkes observations at a higher frequency of 732 MHz reveal a similar parabolic feature with a curvature that scales approximately as the square of the observing wavelength (λ{sup 2}) to the MWA's frequency of 192 MHz. Our analysis suggests that scattering toward PSR J0437–4715 predominantly arises from a compact region about 115 pc from the Earth, which matches well with the expected location of the edge of the Local Bubble that envelopes the local Solar neighborhood. As well as demonstrating new and improved pulsar science capabilities of the MWA, our analysis underscores the potential of low-frequency pulsar observations for gaining valuable insights into the local ISM and for characterizing the ISM toward timing-array pulsars.

  20. A NuSTAR Observation of the Gamma-Ray Emitting Millisecond Pulsar PSR J1723–2837

    Energy Technology Data Exchange (ETDEWEB)

    Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Hui, C. Y. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology (China); Li, K. L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Tam, P. H. T., E-mail: akong@phys.nthu.edu.tw, E-mail: cyhui@cnu.ac.kr [School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082 (China)

    2017-04-20

    We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723–2837. X-ray radiation up to 79 keV is clearly detected, and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power law with a photon index of ∼1.3. We also find X-ray modulations in the 3–10, 10–20, 20–79, and 3–79 keV bands at the 14.8 hr binary orbital period. All of these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723–2837 provides strong evidence that the X-rays are from the intrabinary shock via an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.

  1. Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium

    Science.gov (United States)

    Michilli, D.; Hessels, J. W. T.; Donner, J. Y.; Grießmeier, J.-M.; Serylak, M.; Shaw, B.; Stappers, B. W.; Verbiest, J. P. W.; Deller, A. T.; Driessen, L. N.; Stinebring, D. R.; Bondonneau, L.; Geyer, M.; Hoeft, M.; Karastergiou, A.; Kramer, M.; Osłowski, S.; Pilia, M.; Sanidas, S.; Weltevrede, P.

    2018-05-01

    We have observed a complex and continuous change in the integrated pulse profile of PSR B2217+47, manifested as additional components trailing the main peak. These transient components are detected over 6 yr at 150 MHz using the LOw Frequency ARray (LOFAR), but they are not seen in contemporaneous Lovell observations at 1.5 GHz. We argue that propagation effects in the ionized interstellar medium (IISM) are the most likely cause. The putative structures in the IISM causing the profile variation are roughly half-way between the pulsar and the Earth and have transverse radii R ˜ 30 au. We consider different models for the structures. Under the assumption of spherical symmetry, their implied average electron density is \\overline{n}_e ˜ 100 cm-3. Since PSR B2217+47 is more than an order of magnitude brighter than the average pulsar population visible to LOFAR, similar profile variations would not have been identified in most pulsars, suggesting that subtle profile variations in low-frequency profiles might be more common than we have observed to date. Systematic studies of these variations at low frequencies can provide a new tool to investigate the proprieties of the IISM and the limits to the precision of pulsar timing.

  2. The 26.3-h orbit and multiwavelength properties of the `redback' millisecond pulsar PSR J1306-40

    Science.gov (United States)

    Linares, Manuel

    2018-01-01

    We present the discovery of the variable optical and X-ray counterparts to the radio millisecond pulsar (MSP) PSR J1306-40, recently discovered by Keane et al. We find that both the optical and X-ray fluxes are modulated with the same period, which allows us to measure for the first time the orbital period Porb = 1.097 16[6] d. The optical properties are consistent with a main-sequence companion with spectral type G to mid K and, together with the X-ray luminosity (8.8 × 1031 erg s-1 in the 0.5-10 keV band, for a distance of 1.2 kpc), confirm the redback classification of this pulsar. Our results establish the binary nature of PSR J1306-40, which has the longest Porb among all known compact binary MSPs in the Galactic disc. We briefly discuss these findings in the context of irradiation and intrabinary shock emission in compact binary MSPs.

  3. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, Marco; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, William B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Battelino, Milan; /Royal Inst. Tech., Stockholm; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, Ronaldo; /INFN, Pisa; Berenji, Bijan; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bogaert, G.; /Ecole Polytechnique; Borgland, Anders W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Columbia U. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /IASF, Milan /IASF, Milan /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /LPCE, Orleans /Montpellier U. /Sonoma State U. /Royal Inst. Tech., Stockholm /Stockholm U. /ASI, Rome /NRAO, Charlottesville /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Manchester U. /Montpellier U. /Bari U. /INFN, Bari; /more authors..

    2011-11-30

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 {+-} 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 {+-} 0.004 {+-} 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 {+-} 3 {+-} 11) x 10{sup -8} cm{sup -2} s{sup -1}. The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE{sup -{Gamma}}e{sup (-E/E{sub c})} where the energy E is expressed in GeV. The photon index is {Gamma} = 1.5 {+-} 0.1 {+-} 0.1 and the exponential cut-off is E{sub c} = 2.4 {+-} 0.3 {+-} 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 {+-} 4 rad m{sup -2} but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  4. A DETAILED X-RAY INVESTIGATION OF PSR J2021+4026 AND THE γ-CYGNI SUPERNOVA REMNANT

    Energy Technology Data Exchange (ETDEWEB)

    Hui, C. Y.; Seo, K. A. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Lin, L. C. C.; Huang, R. H. H.; Wu, J. H. K.; Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Hu, C. P.; Chou, Y. [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Trepl, L. [Astrophysikalisches Institut und Universitäts-Sternwarte, Universität Jena, Schillergäßchen 2-3, D-07745 Jena (Germany); Takata, J.; Wang, Y.; Cheng, K. S., E-mail: cyhui@cnu.ac.kr [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong)

    2015-01-20

    We have investigated the field around the radio-quiet γ-ray pulsar, PSR J2021+4026, with a ∼140 ks XMM-Newton observation and ∼56 ks archival Chandra data. Through analyzing the pulsed spectrum, we show that the X-ray pulsation is purely thermal in nature, which suggests that the pulsation originated from a hot polar cap with T ∼ 3 × 10{sup 6} K on the surface of a rotating neutron star. On the other hand, the power-law (PL) component that dominates the pulsar emission in the hard band is originated from off-pulse phases, which possibly comes from a pulsar wind nebula. In re-analyzing the Chandra data, we have confirmed the presence of a bow-shock nebula that extends from the pulsar to the west by ∼10 arcsec. The orientation of this nebular feature suggests that the pulsar is probably moving eastward, which is consistent with the speculated proper motion by extrapolating from the nominal geometrical center of the supernova remnant (SNR) G78.2+2.1 to the current pulsar position. For G78.2+2.1, our deep XMM-Newton observation also enables a study of the central region and part of the southeastern region with superior photon statistics. The column absorption derived for the SNR is comparable to that for PSR J2021+4026, which supports their association. The remnant emission in both of the examined regions is in a non-equilibrium ionization state. Also, the elapsed time of both regions after shock-heating is apparently shorter than the Sedov age of G78.2+2.1. This might suggest that the reverse shock has reached the center not long ago. Apart from PSR J2021+4026 and G78.2+2.1, we have also serendipitously detected an X-ray flash-like event, XMM J202154.7+402855, from this XMM-Newton observation.

  5. THE LIGHT CURVE AND INTERNAL MAGNETIC FIELD OF THE MODE-SWITCHING PULSAR PSR B0943+10

    Energy Technology Data Exchange (ETDEWEB)

    Storch, Natalia I.; Lai, Dong [Center for Space Research, Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Ho, Wynn C. G. [Mathematical Sciences and STAG Research Centre, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Heinke, Craig O. [Department of Physics, University of Alberta, CCIS 4-181, Edmonton, AB, T6G 2E1 (Canada)

    2014-07-10

    A number of radio pulsars exhibit intriguing mode-switching behavior. Recent observations of PSR B0943+10 revealed correlated radio and X-ray mode switches, providing a new avenue for understanding this class of objects. The large X-ray pulse fraction observed during the radio-quiet phase (Q-mode) was previously interpreted as a result of changing obscuration of X-rays by dense magnetosphere plasma. We show that the large X-ray pulse fraction can be explained by including the beaming effect of a magnetic atmosphere, while remaining consistent with the dipole field geometry constrained by radio observations. We also explore a more extreme magnetic field configuration, where a magnetic dipole displaced from the center of the star produces two magnetic polar caps of different sizes and magnetic field strengths. These models are currently consistent with data in radio and X-rays and can be tested or constrained by future X-ray observations.

  6. DISCOVERY OF X-RAY PULSATION FROM THE GEMINGA-LIKE PULSAR PSR J2021+4026

    Energy Technology Data Exchange (ETDEWEB)

    Lin, L. C. C. [General Education Center, China Medical University, Taichung 40402, Taiwan (China); Hui, C. Y.; Seo, K. A., E-mail: cyhui@cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Hu, C. P.; Chou, Y. [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Wu, J. H. K.; Huang, R. H. H. [Institute of Astronomy, National Tsing-Hua University, Hsinchu 30013, Taiwan (China); Trepl, L. [Astrophysikalisches Institut und Universitaets-Sternwarte, Universitaet Jena, Schillergaesschen 2-3, D-07745 Jena (Germany); Takata, J.; Wang, Y.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)

    2013-06-10

    We report the discovery of an X-ray periodicity of {approx}265.3 ms from a deep XMM-Newton observation of the radio-quiet {gamma}-ray pulsar, PSR J2021+4026, located at the edge of the supernova remnant G78.2+2.1 ({gamma}-Cygni). The detected frequency is consistent with the {gamma}-ray pulsation determined by the observation of the Fermi Gamma-ray Space Telescope at the same epoch. The X-ray pulse profile resembles the modulation of a hot spot on the surface of the neutron star. The phase-averaged spectral analysis also suggests that the majority of the observed X-rays have thermal origins. This is the third member in the class of radio-quiet pulsars with significant pulsations detected from both X-ray and {gamma}-ray regimes.

  7. TIMING OBSERVATIONS OF PSR J1023+0038 DURING A LOW-MASS X-RAY BINARY STATE

    Energy Technology Data Exchange (ETDEWEB)

    Jaodand, Amruta; Archibald, Anne M.; Hessels, Jason W. T.; Bassa, Cees; Deller, Adam T. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); D’Angelo, Caroline R.; Patruno, Alessandro [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

    2016-10-20

    Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year timescales, between rotation-powered radio millisecond pulsar (RMSP) and accretion-powered low-mass X-ray binary (LMXB) states. The tMSPs have raised several questions related to the nature of accretion flow in their LMXB state and the mechanism that causes the state switch. The discovery of coherent X-ray pulsations from PSR J1023+0038 (while in the LMXB state) provides us with the first opportunity to perform timing observations and to compare the neutron star’s spin variation during this state to the measured spin-down in the RMSP state. Whereas the X-ray pulsations in the LMXB state likely indicate that some material is accreting onto the neutron star’s magnetic polar caps, radio continuum observations indicate the presence of an outflow. The fraction of the inflowing material being ejected is not clear, but it may be much larger than that reaching the neutron star’s surface. Timing observations can measure the total torque on the neutron star. We have phase-connected nine XMM-Newton observations of PSR J1023+0038 over the last 2.5 years of the LMXB state to establish a precise measurement of spin evolution. We find that the average spin-down rate as an LMXB is 26.8 ± 0.4% faster than the rate (−2.39 × 10{sup −15} Hz s{sup −1}) determined during the RMSP state. This shows that negative angular momentum contributions (dipolar magnetic braking, and outflow) exceed positive ones (accreted material), and suggests that the pulsar wind continues to operate at a largely unmodified level. We discuss implications of this tight observational constraint in the context of possible accretion models.

  8. Variations of the harmonic components of the X-ray pulse profile of PSR B1509–58

    International Nuclear Information System (INIS)

    Pradhan Pragati; Paul Biswajit; Raichur Harsha; Paul Bikash Chandra

    2015-01-01

    We used the Fourier decomposition technique to investigate the stability of the X-ray pulse profile of a young pulsar PSR B1509–58 by studying the relative amplitudes and phase differences of its harmonic components with respect to the fundamental using data from the Rossi X-Ray Timing Explorer. Like most young rotation powered pulsars, PSR B1509–58 has a high spin down rate. It also has less timing noise, allowing accurate measurement of higher order frequency derivatives which in turn helps in the study of the physics of pulsar spin down. Detailed investigation of pulse profiles over the years will help us establish any possible connection between the timing characteristics and the high energy emission characteristics for this pulsar. Furthermore, the study of pulse profiles of short period X-ray pulsars can also be useful when used as a means of interplanetary navigation. The X-ray pulse profile of this source has been analyzed for 15 yr (1996–2011). The long term average amplitudes of the first, second and third harmonics (and their standard deviation for individual measurements) compared to the fundamental are 36.9% (1.7%), 13.4% (1.9%) and 9.4% (1.8%) respectively. Similarly, the phases of the three harmonics (and standard deviations) with respect to the fundamental are 0.36 (0.06), 1.5 (0.2) and 2.5 (0.3) radian respectively. We do not find any significant variation of the harmonic components of the pulse profile in comparison to the fundamental. (research papers)

  9. A PROPELLER MODEL FOR THE SUB-LUMINOUS STATE OF THE TRANSITIONAL MILLISECOND PULSAR PSR J1023+0038

    Energy Technology Data Exchange (ETDEWEB)

    Papitto, A.; Torres, D. F. [Institute of Space Sciences (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N, E-08193, Cerdanyola del Vallés, Barcelona (Spain)

    2015-07-01

    The discovery of millisecond pulsars switching between states powered either by the rotation of their magnetic field or by the accretion of matter has recently proved the tight link shared by millisecond radio pulsars and neutron stars in low-mass X-ray binaries. Transitional millisecond pulsars also show an enigmatic intermediate state in which the neutron star is surrounded by an accretion disk and emits coherent X-ray pulsations, but is sub-luminous in X-rays with respect to accreting neutron stars, and is brighter in gamma-rays than millisecond pulsars in the rotation-powered state. Here, we model the X-ray and gamma-ray emission observed from PSR J1023+0038 in such a state based on the assumptions that most of the disk in-flow is propelled away by the rapidly rotating neutron star magnetosphere, and that electrons can be accelerated to energies of a few GeV at the turbulent disk–magnetosphere boundary. We show that the synchrotron and self-synchrotron Compton emission coming from such a region, together with the hard disk emission typical of low states of accreting compact objects, is able to explain the radiation observed in the X-ray and gamma-ray bands. The average emission observed from PSR J1023+0038 is modeled by a disk in-flow with a rate of 1–3 × 10{sup −11} M{sub ⊙} yr{sup −1}, truncated at a radius ranging between 30 and 45 km, compatible with the hypothesis of a propelling magnetosphere. We compare the results we obtained with models that assume that a rotation-powered pulsar is turned on, showing how the spin-down power released in similar scenarios is hardly able to account for the magnitude of the observed emission.

  10. 75 FR 60749 - Policy on Payment System Risk

    Science.gov (United States)

    2010-10-01

    ... FEDERAL RESERVE SYSTEM [Docket No. OP-1345] Policy on Payment System Risk AGENCY: Board of... of its Policy on Payment System Risk (PSR). The revisions explicitly recognize the role of the... payment flows for the banking system, while also helping to mitigate credit exposures of the Federal...

  11. Observing and Modeling the Gamma-Ray Emission from Pulsar/Pulsar Wind Nebula Complex PSR J0205+6449/3C 58

    Science.gov (United States)

    Li, Jian; Torres, Diego F.; Lin, Ting Ting; Grondin, Marie-Helene; Kerr, Matthew; Lemoine-Goumard, Marianne; de Oña Wilhelmi, Emma

    2018-05-01

    We present the results of the analysis of eight years of Fermi-LAT data of the pulsar/pulsar wind nebula complex PSR J0205+6449/3C 58. Using a contemporaneous ephemeris, we carried out a detailed analysis of PSR J0205+6449 both during its off-peak and on-peak phase intervals. 3C 58 is significantly detected during the off-peak phase interval. We show that the spectral energy distribution at high energies is the same disregarding the phases considered, and thus that this part of the spectrum is most likely dominated by the nebula radiation. We present results of theoretical models of the nebula and the magnetospheric emission that confirm this interpretation. Possible high-energy flares from 3C 58 were searched for, but none were unambiguously identified.

  12. PSR J1856+0245: Arecibo discovery of a young, energetic pulsar coincident with the TeV γ-ray source HESS J1857+026

    NARCIS (Netherlands)

    Hessels, J.W.T.; Nice, D.J.; Gaensler, B.M.; Kaspi, V.M.; Lorimer, D.R.; Champion, D.J.; Lyne, A.G.; Kramer, M.; Cordes, J.M.; Freire, P.C.C.; Camilo, F.; Ransom, S.M.; Deneva, J.S.; Bhat, N.D.R.; Cognard, I.; Crawford, F.; Jenet, F.A.; Kasian, L.; Lazarus, P.; van Leeuwen, J.; McLaughlin, M.A.; Stairs, I.H.; Stappers, B.W.; Venkataraman, A.

    2008-01-01

    We present the discovery of the Vela-like radio pulsar J1856+0245 in the Arecibo PALFA survey. PSR J1856+0245 has a spin period of 81 ms, a characteristic age of 21 kyr, and a spin-down luminosity (E) over dot = 4.6 x 10(36) ergs s(-1). It is positionally coincident with the TeV gamma-ray source

  13. Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Baring, Matthew G.; /Rice U.; Bastieri, Denis; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle; Caliandro, G.A.; /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /NASA, Goddard /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Trieste /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; /more authors..

    2009-05-15

    Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.

  14. Crystal Structures of KPC-2[beta]-Lactamase in Complex with 3-Nitrophenyl Boronic Acid and the Penam Sulfone PSR-3-226

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Wei; Bethel, Christopher R.; Papp-Wallace, Krisztina M.; Pagadala, Sundar Ram Reddy; Nottingham, Micheal; Fernandez, Daniel; Buynak, John D.; Bonomo, Robert A.; van den Akker, Focco (Case Western); (Stokes); (SMU)

    2012-08-01

    Class A carbapenemases are a major threat to the potency of carbapenem antibiotics. A widespread carbapenemase, KPC-2, is not easily inhibited by {beta}-lactamase inhibitors (i.e., clavulanic acid, sulbactam, and tazobactam). To explore different mechanisms of inhibition of KPC-2, we determined the crystal structures of KPC-2 with two {beta}-lactamase inhibitors that follow different inactivation pathways and kinetics. The first complex is that of a small boronic acid compound, 3-nitrophenyl boronic acid (3-NPBA), bound to KPC-2 with 1.62-{angstrom} resolution. 3-NPBA demonstrated a Km value of 1.0 {+-} 0.1 {micro}M (mean {+-} standard error) for KPC-2 and blocks the active site by making a reversible covalent interaction with the catalytic S70 residue. The two boron hydroxyl atoms of 3-NPBA are positioned in the oxyanion hole and the deacylation water pocket, respectively. In addition, the aromatic ring of 3-NPBA provides an edge-to-face interaction with W105 in the active site. The structure of KPC-2 with the penam sulfone PSR-3-226 was determined at 1.26-{angstrom} resolution. PSR-3-226 displayed a K{sub m} value of 3.8 {+-} 0.4 {micro}M for KPC-2, and the inactivation rate constant (kinact) was 0.034 {+-} 0.003 s{sup -1}. When covalently bound to S70, PSR-3-226 forms a trans-enamine intermediate in the KPC-2 active site. The predominant active site interactions are generated via the carbonyl oxygen, which resides in the oxyanion hole, and the carboxyl moiety of PSR-3-226, which interacts with N132, N170, and E166. 3-NPBA and PSR-3-226 are the first {beta}-lactamase inhibitors to be trapped as an acyl-enzyme complex with KPC-2. The structural and inhibitory insights gained here could aid in the design of potent KPC-2 inhibitors.

  15. Quaternion Based Thermal Condition Monitoring System

    Science.gov (United States)

    Wong, Wai Kit; Loo, Chu Kiong; Lim, Way Soong; Tan, Poi Ngee

    In this paper, we will propose a new and effective machine condition monitoring system using log-polar mapper, quaternion based thermal image correlator and max-product fuzzy neural network classifier. Two classification characteristics namely: peak to sidelobe ratio (PSR) and real to complex ratio of the discrete quaternion correlation output (p-value) are applied in the proposed machine condition monitoring system. Large PSR and p-value observe in a good match among correlation of the input thermal image with a particular reference image, while small PSR and p-value observe in a bad/not match among correlation of the input thermal image with a particular reference image. In simulation, we also discover that log-polar mapping actually help solving rotation and scaling invariant problems in quaternion based thermal image correlation. Beside that, log-polar mapping can have a two fold of data compression capability. Log-polar mapping can help smoother up the output correlation plane too, hence makes a better measurement way for PSR and p-values. Simulation results also show that the proposed system is an efficient machine condition monitoring system with accuracy more than 98%.

  16. X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - the Final ROSAT Observations

    CERN Document Server

    Becker, W; Bäcker, A N; Lommen, D; Becker, Werner; Tr"umper, Joachim; Backer, Andrea N.Lommen & Donald C.

    2000-01-01

    We report on X-ray observations of the solitary 4.8 ms pulsar PSR J0030+0451. The pulsar was one of the last targets observed in DEC-98 by the ROSAT PSPC. X-ray pulses are detected on a $4.5\\sigma$ level and make the source the $11^{th}$ millisecond pulsar detected in the X-ray domain. The pulsed fraction is found to be $69\\pm18%$. The X-ray pulse profile is characterized by two narrow peaks which match the gross pulse profile observed at 1.4 GHz. Assuming a Crab-like spectrum the X-ray flux is in the range $f_x= 2-3\\times 10^{-13}$ erg s$^{-1}$ cm$^{-2} $ ($0.1-2.4$ keV), implying an X-ray efficiency of $L_x/\\dot{E}\\sim 0.5-5 \\times 10^{-3} (d/0.23 {kpc})^2$.

  17. THE MASSIVE PULSAR PSR J1614-2230: LINKING QUANTUM CHROMODYNAMICS, GAMMA-RAY BURSTS, AND GRAVITATIONAL WAVE ASTRONOMY

    International Nuclear Information System (INIS)

    Oezel, Feryal; Psaltis, Dimitrios; Ransom, Scott; Demorest, Paul; Alford, Mark

    2010-01-01

    The recent measurement of the Shapiro delay in the radio pulsar PSR J1614-2230 yielded a mass of 1.97 ± 0.04 M sun , making it the most massive pulsar known to date. Its mass is high enough that, even without an accompanying measurement of the stellar radius, it has a strong impact on our understanding of nuclear matter, gamma-ray bursts (GRBs), and the generation of gravitational waves from coalescing neutron stars. This single high-mass value indicates that a transition to quark matter in neutron-star cores can occur at densities comparable to the nuclear saturation density only if the quarks are strongly interacting and are color superconducting. We further show that a high maximum neutron-star mass is required if short-duration GRBs are powered by coalescing neutron stars and, therefore, this mechanism becomes viable in the light of the recent measurement. Finally, we argue that the low-frequency (≤500 Hz) gravitational waves emitted during the final stages of neutron-star coalescence encode the properties of the equation of state because neutron stars consistent with this measurement cannot be centrally condensed. This will facilitate the measurement of the neutron star equation of state with Advanced LIGO/Virgo.

  18. Possible contraction of the members of the binary pulsar PSR 1913+16 and its astrophysical consequences

    International Nuclear Information System (INIS)

    Spyrou, N.

    1983-01-01

    It is proposed that the small difference between the observed and the theoretically predicted decrease of the orbital period of the Binary Pulsar PSR 1913+16 is not due to the insufficiency of the quadrupole formula and can be attributed to a mass-energy loss due to the contraction of the binary's members. Assuming that the pair's primary is a typical, noncontracting pulsar, is in favour of a slowly contracting, neutron-star companion, thus limiting the member's radii to at most 25 km and 28 km, respectively. The primary's computed total absolute luminosity is in excellent agreement with the observed upper limit of its X-ray and optical luminosities. Moreover, the companion's slow contraction rate implies that its present total absolute luminosity presents a maximum at wavelengths characteristic of X-rays. Finally, it suggests that if the energy-loss remains constant, the duration of the contraction phase will be of the order of 10 8 y and the final radius about 25 km. (Auth.)

  19. The First Continuous Optical Monitoring of the Transitional Millisecond Pulsar PSR J1023+0038 with Kepler

    Science.gov (United States)

    Papitto, A.; Rea, N.; Coti Zelati, F.; de Martino, D.; Scaringi, S.; Campana, S.; de Ońa Wilhelmi, E.; Knigge, C.; Serenelli, A.; Stella, L.; Torres, D. F.; D’Avanzo, P.; Israel, G. L.

    2018-05-01

    We report on the first continuous, 80-day optical monitoring of the transitional millisecond pulsar PSR J1023+0038 carried out in mid 2017 with Kepler in the K2 configuration, when an X-ray subluminous accretion disk was present in the binary. Flares lasting from minutes to 14 hr were observed for 15.6% of the time, which is a larger fraction than previously reported on the basis of X-ray and past optical observations, and more frequently when the companion was at superior conjunction of the orbit. A sinusoidal modulation at the binary orbital period was also present with an amplitude of ≃16%, which varied by a few percent over timescales of days, and with a maximum that took place 890 ± 85 s earlier than the superior conjunction of the donor. We interpret this phenomena in terms of reprocessing of the X-ray emission by an asymmetrically heated companion star surface and/or a non-axisymmetric outflow possibly launched close to the inner Lagrangian point. Furthermore, the non-flaring average emission varied by up to ≈40% over a timescale of days in the absence of correspondingly large variations of the irradiating X-ray flux. The latter suggests that the observed changes in the average optical luminosity might be due to variations of the geometry, size, and/or mass accretion rate in the outer regions of the accretion disk.

  20. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    Science.gov (United States)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; hide

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  1. 78 FR 70046 - Payment System Risk Policy; Daylight Overdraft Posting Rules

    Science.gov (United States)

    2013-11-22

    ... FEDERAL RESERVE SYSTEM [Docket No. OP--1471] Payment System Risk Policy; Daylight Overdraft... Reserve Policy on Payment System Risk (PSR policy) to eliminate certain posting rules to conform with... Services Analyst (202- 452-2404), Division of Reserve Bank Operations and Payment Systems. For users of...

  2. Comparing models of the periodic variations in spin-down and beamwidth for PSR B1828-11

    Science.gov (United States)

    Ashton, G.; Jones, D. I.; Prix, R.

    2016-05-01

    We build a framework using tools from Bayesian data analysis to evaluate models explaining the periodic variations in spin-down and beamwidth of PSR B1828-11. The available data consist of the time-averaged spin-down rate, which displays a distinctive double-peaked modulation, and measurements of the beamwidth. Two concepts exist in the literature that are capable of explaining these variations; we formulate predictive models from these and quantitatively compare them. The first concept is phenomenological and stipulates that the magnetosphere undergoes periodic switching between two metastable states as first suggested by Lyne et al. The second concept, precession, was first considered as a candidate for the modulation of B1828-11 by Stairs et al. We quantitatively compare models built from these concepts using a Bayesian odds ratio. Because the phenomenological switching model itself was informed by these data in the first place, it is difficult to specify appropriate parameter-space priors that can be trusted for an unbiased model comparison. Therefore, we first perform a parameter estimation using the spin-down data, and then use the resulting posterior distributions as priors for model comparison on the beamwidth data. We find that a precession model with a simple circular Gaussian beam geometry fails to appropriately describe the data, while allowing for a more general beam geometry provides a good fit to the data. The resulting odds between the precession model (with a general beam geometry) and the switching model are estimated as 102.7±0.5 in favour of the precession model.

  3. A BROADBAND RADIO STUDY OF THE AVERAGE PROFILE AND GIANT PULSES FROM PSR B1821-24A

    Energy Technology Data Exchange (ETDEWEB)

    Bilous, A. V. [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Pennucci, T. T. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Demorest, P. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Ransom, S. M., E-mail: a.bilous@science.ru.nl [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

    2015-04-20

    We present the results of a wideband (720–2400 MHz) study of PSR B1821–24A (J1824–2452A, M28A), an energetic millisecond pulsar (MSP) visible in radio, X-rays and γ-rays. In radio, the pulsar has a complex average profile that spans ≳85% of the spin period and exhibits strong evolution with observing frequency. For the first time we measure phase-resolved polarization properties and spectral indices of radio emission throughout almost all of the on-pulse window. We synthesize our findings with high-energy information to compare M28A to other known γ-ray MSPs and to speculate that M28A’s radio emission originates in multiple regions within its magnetosphere (i.e., both in the slot or outer gaps near the light cylinder and at lower altitudes above the polar cap). M28A is one of a handful of pulsars that are known to emit giant radio pulses (GRPs)—short, bright radio pulses of unknown nature. We report a drop in the linear polarization of the average profile in both windows of GRP generation and also a “W”-shaped absorption feature (resembling a double notch), partly overlapping with one of the GRP windows. The GRPs themselves have broadband spectra consisting of multiple patches with Δν/ν ∼ 0.07. Although our time resolution was not sufficient to resolve the GRP structure on the μs scale, we argue that GRPs from this pulsar most closely resemble the GRPs from the main pulse of the Crab pulsar, which consist of a series of narrowband nanoshots.

  4. PULSE INTENSITY MODULATION AND THE TIMING STABILITY OF MILLISECOND PULSARS: A CASE STUDY OF PSR J1713+0747

    Energy Technology Data Exchange (ETDEWEB)

    Shannon, Ryan M. [CSIRO Astronomy and Space Science, Box 76, Epping, NSW 1710 (Australia); Cordes, James M., E-mail: ryan.shannon@csiro.au, E-mail: cordes@astro.cornell.edu [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)

    2012-12-10

    Most millisecond pulsars, like essentially all other radio pulsars, show timing errors well in excess of what is expected from additive radiometer noise alone. We show that changes in amplitude, shape, and pulse phase for the millisecond pulsar J1713+0747 cause this excess error. These changes appear to be uncorrelated from one pulse period to the next. The resulting time of arrival (TOA) variations are correlated across a wide frequency range and is observed with different backend processors on different days, confirming that they are intrinsic in origin and not an instrumental effect or caused by strongly frequency-dependent interstellar scattering. Centroids of single pulses show an rms phase variation Almost-Equal-To 40 {mu}s, which dominates the timing error and is the same phase jitter phenomenon long known in slower spinning, canonical pulsars. We show that the amplitude modulations of single pulses are modestly correlated with their arrival time fluctuations. We also demonstrate that single-pulse variations are completely consistent with arrival time variations of pulse profiles obtained by integrating N pulses such that the arrival-time error decreases proportional to 1/{radical}N. We investigate methods for correcting TOAs for these pulse-shape changes, including multi-component TOA fitting and principal component analysis. These techniques are not found to improve the timing precision of the observations. We conclude that when pulse-shape changes dominate timing errors, the timing precision of PSR J1713+0747 can be only improved by averaging over a larger number of pulses.

  5. Mechanism of the X-ray and Soft Gamma-ray Emissions from the High Magnetic Field Pulsar: PSR B1509-58

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2013-06-01

    Full Text Available We use the outer gap model to explain the spectrum and the energy dependent light curves of the X-ray and soft γ-ray radiations of the spin-down powered pulsar PSR B1509-58. In the outer gap model, most pairs inside the gap are created around the null charge surface and the gap’s electric field separates the opposite charges to move in opposite directions. Consequently, the region from the null charge surface to the light cylinder is dominated by the outflow current and that from the null charge surface to the star is dominated by the inflow current. We suggest that the viewing angle of PSR B1509-58 only receives the inflow radiation. The incoming curvature photons are converted to pairs by the strong magnetic field of the star. The X-rays and soft γ-rays of PSR B1509-58 result from the synchrotron radiation of these pairs. The magnetic pair creation requires a large pitch angle, which makes the pulse profile of the synchrotron radiation distinct from that of the curvature radiation. We carefully trace the pulse profiles of the synchrotron radiation with different pitch angles. We find that the differences between the light curves of different energy bands are due to the different pitch angles of the secondary pairs, and the second peak appearing at E > 10 MeV comes from the region near the star, where the stronger magnetic field allows the pair creation to happen with a smaller pitch angle.

  6. Lessons from shielding retrofits at the LAMPF/LANSCE/PSR accelerator, beam lines and target facilities

    International Nuclear Information System (INIS)

    Macek, R.J.

    1994-01-01

    The experience in the past 7 years to improve the shielding and radiation control systems at the Los Alamos Meson Physics Facility (LAMPF) and the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) provides important lessons for the design of radiation control systems at future, high beam power proton accelerator facilities. Major issues confronted and insight gained in developing shielding criteria and in the use of radiation interlocks are discussed. For accelerators and beam lines requiring hands-on-maintenance, our experience suggests that shielding criteria based on accident scenarios will be more demanding than criteria based on routinely encountered beam losses. Specification and analysis of the appropriate design basis accident become all important. Mitigation by active protection systems of the consequences of potential, but severe, prompt radiation accidents has been advocated as an alternate choice to shielding retrofits for risk management at both facilities. Acceptance of active protection systems has proven elusive primarily because of the difficulty in providing convincing proof that failure of active systems (to mitigate the accident) is incredible. Results from extensive shielding assessment studies are presented including data from experimental beam spill tests, comparisons with model estimates, and evidence bearing on the limitations of line-of-sight attenuation models in complex geometries. The scope and significant characteristics of major shielding retrofit projects at the LAMPF site are illustrated by the project to improve the shielding beneath a road over a multiuse, high-intensity beam line (Line D)

  7. Detection of VHE gamma-ray emission from the vicinity of PSR B1706-44 with H.E.S.S.

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, Ryan C.G.; Ona Wilhelmi, Emma de [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Terrier, Regis [APC, CNRS, Univ. Paris-7 (France); Stegmann, Christian [Universitaet Erlangen-Nuernberg, Erlangen (Germany). Physikalisches Institut; Khelifi, Bruno [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Jager, Okkie C. de [Unit for Space Physics, North-West Univ., Potchefstroom (South Africa)

    2010-07-01

    The gamma-ray pulsar PSR B1706-44 and the adjacent supernova remnant (SNR) candidate G343.1-2.3 were observed by H.E.S.S. during a dedicated observational campaign in 2007. A new source of very-high-energy (VHE;E>100 GeV) gamma-ray emission, HESS J1708-443, was discovered with its centroid at RA(J2000.0)=17 h 8 m 10 s and Dec (J2000.0)=-44 d 21{sup '} ({+-}3{sup '} statistical error on each axis). The VHE gamma-ray source is significantly more extended than the H.E.S.S. point-spread function and has an intrinsic Gaussian width of 0.29 {+-}0.04 . Its energy spectrum can be described by a power law with a photon index=2.0{+-}0.1 (stat){+-}0.2 (syst). The integral flux measured between 1 and 10 TeV is {proportional_to}17% of the Crab Nebula flux in the same energy range. The possible associations with the energetic PSR B1706-44, also recently detected in the GeV domain with Fermi/LAT and AGILE, and SNR G343.1-2.3 are discussed.

  8. Binary pulsar PSR 1718-19 contains a stripped main-sequence turn-off star

    International Nuclear Information System (INIS)

    Zwitter, T.

    1993-05-01

    Lyne et al. (1993) have recently announced the discovery of a 1-second globular cluster pulsar, 1718-19, in a 6.2-hour binary system which is embedded in a cloud of material originating from the companion star. However the incident flux of the pulsar's radiation on the companion is too low to ablate it and a main sequence companion is too small to fill its Roche lobe. Here I argue that the companion is a stripped turn-off star of 0.2-0.4 solar masses (M sun ) and with approx. 0.1M sun helium core. It has approx. 1.8-times larger radius than a main sequence star of equal mass. Its position in the Hertzsprung-Russell diagram overlaps that of a ∼ 0.65M sun main-sequence star. The evolutionary state of the companion and the highly magnetized slowly rotating neutron star place the system on the verge of the low mass X-ray binary phase. (author). 19 refs, 2 figs

  9. Comprehensive evaluation of ecological security in mining area based on PSR-ANP-GRAY.

    Science.gov (United States)

    He, Gang; Yu, Baohua; Li, Shuzhou; Zhu, Yanna

    2017-09-06

    With the large exploitation of mineral resources, a series of problems have appeared in the ecological environment of the mining area. Therefore, evaluating the ecological security of mining area is of great significance to promote its healthy development. In this paper, the evaluation index system of ecological security in mining area was constructed from three dimensions of nature, society and economy, combined with Pressure-State-Response framework model. Then network analytic hierarchy process and GRAY relational analysis method were used to evaluate the ecological security of the region, and the weighted correlation degree of ecological security was calculated through the index data of a coal mine from 2012 to 2016 in China. The results show that the ecological security in the coal mine area is on the rise as a whole, though it alternatively rose and dropped from 2012 to 2016. Among them, the ecological security of the study mining area is at the general security level from 2012 to 2015, and at a relatively safe level in 2016. It shows that the ecological environment of the study mining area can basically meet the requirement of the survival and development of the enterprises.

  10. PROBING RELATIVISTIC WINDS: THE CASE OF PSR J07370-3039 A and B

    International Nuclear Information System (INIS)

    Arons, J

    2004-01-01

    We propose synchrotron absorption in a magnetosheath forming a cocoon around the magnetosphere of pulsar B to be the origin of the eclipse phenomena seen in the recently discovered double pulsar system PSRJ07370-3039 A and B. The magnetosheath enfolds the magnetosphere of pulsar B, where the relativistic wind from A collides with B's magnetic field. If this model is correct, it predicts the eclipses will clear at frequencies higher than those of the observations reported to date (nominally, above ν ∼ 5 GHz.) The model also predicts synchrotron emission at the level of a few to 10 (micro)Jy, peaking at ν ∼ 2.5 GHz with possible orbital modulation. We use simplified semi-analytic models to elucidate the structure of the B magnetosphere, showing that the A wind's dynamic pressure confines B's magnetic field to within a radius less than 50,000 km from B, smaller than B's light cylinder radius, on the ''daytime'' side (the side facing A). Downstream of B (''nightime''), B forms a magnetotail. We use particle-in-cell simulations to include the effects of magnetospheric rotation, showing that the magnetosheath has an asymmetric density distribution which may be responsible for the observed eclipse asymmetries. We use simple estimates based upon the magnetic reconnection observed in the simulations to derive a ''propellor'' spindown torque on B, which is the dominant mode of angular mementum extraction from this star. Application of this torque to B's observed spindown yields a polar dipole field ∼ 7 x 10 11 Gauss (magnetic moment (micro) B ∼ 3.5 x 10 29 cgs). This torque has a braking index of unity. We show that the model can explain the known eclipses only if the A wind's density is at least 4 orders of magnitude greater than is expected from existing popular models of pair creation in pulsars. We discuss the implications of this result for our general understanding of pulsar physics

  11. Deficiency of RgpG Causes Major Defects in Cell Division and Biofilm Formation, and Deficiency of LytR-CpsA-Psr Family Proteins Leads to Accumulation of Cell Wall Antigens in Culture Medium by Streptococcus mutans.

    Science.gov (United States)

    De, Arpan; Liao, Sumei; Bitoun, Jacob P; Roth, Randy; Beatty, Wandy L; Wu, Hui; Wen, Zezhang T

    2017-09-01

    Streptococcus mutans is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen. S. mutans strains deficient in rgpG , encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The rgpG deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the rgpG mutant existed primarily in chains of swollen, "squarish" dividing cells. Deficiency of rgpG also causes significant reduction in biofilm formation ( P cell envelope biogenesis, were constructed using the rgpG mutant. There were no major differences in growth rates between the wild-type strain and the rgpG brpA and rgpG psr double mutants, but the growth rate of the rgpG brpA psr triple mutant was reduced drastically ( P cells with multiple asymmetric septa. When analyzed by immunoblotting, the rgpG mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the brpA and psr single mutants. These results suggest that RgpG in S. mutans plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope. IMPORTANCE Streptococcus mutans , a major etiological agent of human dental caries, produces rhamnose-glucose polysaccharide (RGP) as the major cell wall antigen. This study provides direct evidence that deficiency of RgpG, the first enzyme of the RGP biosynthesis pathway, caused major defects in cell division and morphology and reduced biofilm formation by S. mutans , indicative of a significant role of RGP in cell division and biofilm formation in S. mutans These results are novel not only in S. mutans , but also other streptococci that produce RGP. This study also shows that the LytR-CpsA-Psr family proteins BrpA and Psr in S. mutans are involved in attachment of RGP and probably

  12. Some Arguments in Support of the Association of PSR B1706-44 with the Supernova Remnant G343.1-2.3

    Science.gov (United States)

    Bock, D. C.-J.; Gvaramadze, V. V.

    We present some arguments in support of the association of the pulsar PSR B1706-44 with the supernova remnant G343.1-2.3, based on the idea that these objects could be the result of a supernova explosion within a mushroom-like cavity (created by the supernova progenitor wind breaking out of the parent molecular cloud). We suggest that in addition to the known bright "half" of G343.1-2.3 there should exist a more extended and weaker component, such that the actual shape of G343.1 2.3 is similar to that of the well-known SNR VRO 42.05.01. We have found such a component in archival radio data.

  13. Prospects for Probing Strong Gravity with a Pulsar-Black Hole System

    Science.gov (United States)

    Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-01-01

    The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.

  14. Simulation realization of 2-D wavelength/time system utilizing MDW code for OCDMA system

    Science.gov (United States)

    Azura, M. S. A.; Rashidi, C. B. M.; Aljunid, S. A.; Endut, R.; Ali, N.

    2017-11-01

    This paper presents a realization of Wavelength/Time (W/T) Two-Dimensional Modified Double Weight (2-D MDW) code for Optical Code Division Multiple Access (OCDMA) system based on Spectral Amplitude Coding (SAC) approach. The MDW code has the capability to suppress Phase-Induce Intensity Noise (PIIN) and minimizing the Multiple Access Interference (MAI) noises. At the permissible BER 10-9, the 2-D MDW (APD) had shown minimum effective received power (Psr) = -71 dBm that can be obtained at the receiver side as compared to 2-D MDW (PIN) only received -61 dBm. The results show that 2-D MDW (APD) has better performance in achieving same BER with longer optical fiber length and with less received power (Psr). Also, the BER from the result shows that MDW code has the capability to suppress PIIN ad MAI.

  15. Simulation realization of 2-D wavelength/time system utilizing MDW code for OCDMA system

    Directory of Open Access Journals (Sweden)

    Azura M. S. A.

    2017-01-01

    Full Text Available This paper presents a realization of Wavelength/Time (W/T Two-Dimensional Modified Double Weight (2-D MDW code for Optical Code Division Multiple Access (OCDMA system based on Spectral Amplitude Coding (SAC approach. The MDW code has the capability to suppress Phase-Induce Intensity Noise (PIIN and minimizing the Multiple Access Interference (MAI noises. At the permissible BER 10-9, the 2-D MDW (APD had shown minimum effective received power (Psr = -71 dBm that can be obtained at the receiver side as compared to 2-D MDW (PIN only received -61 dBm. The results show that 2-D MDW (APD has better performance in achieving same BER with longer optical fiber length and with less received power (Psr. Also, the BER from the result shows that MDW code has the capability to suppress PIIN ad MAI.

  16. THE INCLINATION ANGLE AND EVOLUTION OF THE BRAKING INDEX OF PULSARS WITH PLASMA-FILLED MAGNETOSPHERE: APPLICATION TO THE HIGH BRAKING INDEX OF PSR J1640–4631

    International Nuclear Information System (INIS)

    Ekşi, K. Y.; Andaç, I. C.; Çıkıntoğlu, S.; Motlagh, A. Vahdat; Gügercinoğlu, E.; Kızıltan, B.

    2016-01-01

    The recently discovered rotationally powered pulsar PSR J1640–4631 is the first to have a braking index measured, with high enough precision, that is greater than 3. An inclined magnetic rotator in vacuum or plasma would be subject not only to spin-down but also to an alignment torque. The vacuum model can address the braking index only for an almost orthogonal rotator, which is incompatible with the single-peaked pulse profile. The magnetic dipole model with the corotating plasma predicts braking indices between 3 and 3.25. We find that the braking index of 3.15 is consistent with two different inclination angles, 18.°5 ± 3° and 56° ± 4°. The smaller angle is preferred given that the pulse profile has a single peak and the radio output of the source is weak. We infer the change in the inclination angle to be at the rate −0.°23 per century, three times smaller in absolute value than the rate recently observed for the Crab pulsar.

  17. Experimental assessment of the performance of a proposed lead slowing-down spectrometer at WNR/PSR [Weapons Neutron Research/Proton Storage Ring

    International Nuclear Information System (INIS)

    Moore, M.S.; Koehler, P.E.; Michaudon, A.; Schelberg, A.; Danon, Y.; Block, R.C.; Slovacek, R.E.; Hoff, R.W.; Lougheed, R.W.

    1990-01-01

    In November 1989, we carried out a measurement of the fission cross section of 247 Cm, 250 Cf, and 254 Es on the Rensselaer Intense Neutron Source (RINS) at Rensselaer Polytechnic Institute (RPI). In July 1990, we carried out a second measurement, using the same fission chamber and electronics, in beam geometry at the Los Alamos Neutron Scattering Center (LANSCE) facility. Using the relative count rates observed in the two experiments, and the flux-enhancement factors determined by the RPI group for a lead slowing-down spectrometer compared to beam geometry, we can assess the performance of a spectrometer similar to RINS, driven by the Proton Storage Ring (PSR) at the Los Alamos National Laboratory. With such a spectrometer, we find that is is feasible to make measurements with samples of 1 ng for fission 1 μg for capture, and of isotopes with half-lives of tens of minutes. It is important to note that, while a significant amount of information can be obtained from the low resolution RINS measurement, a definitive determination of average properties, including the level density, requires that the resonance structure be resolved. 12 refs., 5 figs., 3 tabs

  18. Experimental assessment of the performance of a proposed lead slowing-down spectrometer at WNR/PSR (Weapons Neutron Research/Proton Storage Ring)

    Energy Technology Data Exchange (ETDEWEB)

    Moore, M.S.; Koehler, P.E.; Michaudon, A.; Schelberg, A. (Los Alamos National Lab., NM (USA)); Danon, Y.; Block, R.C.; Slovacek, R.E. (Rensselaer Polytechnic Inst., Troy, NY (USA)); Hoff, R.W.; Lougheed, R.W. (Lawrence Livermore National Lab., CA (USA))

    1990-01-01

    In November 1989, we carried out a measurement of the fission cross section of {sup 247}Cm, {sup 250}Cf, and {sup 254}Es on the Rensselaer Intense Neutron Source (RINS) at Rensselaer Polytechnic Institute (RPI). In July 1990, we carried out a second measurement, using the same fission chamber and electronics, in beam geometry at the Los Alamos Neutron Scattering Center (LANSCE) facility. Using the relative count rates observed in the two experiments, and the flux-enhancement factors determined by the RPI group for a lead slowing-down spectrometer compared to beam geometry, we can assess the performance of a spectrometer similar to RINS, driven by the Proton Storage Ring (PSR) at the Los Alamos National Laboratory. With such a spectrometer, we find that is is feasible to make measurements with samples of 1 ng for fission 1 {mu}g for capture, and of isotopes with half-lives of tens of minutes. It is important to note that, while a significant amount of information can be obtained from the low resolution RINS measurement, a definitive determination of average properties, including the level density, requires that the resonance structure be resolved. 12 refs., 5 figs., 3 tabs.

  19. GMRT DISCOVERY OF PSR J1544+4937: AN ECLIPSING BLACK-WIDOW PULSAR IDENTIFIED WITH A FERMI-LAT SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, B.; Roy, J.; Gupta, Y. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Ray, P. S.; Wolff, M. T.; Wood, K. S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Bhattacharya, D. [Inter-University Centre for Astronomy and Astrophysics, Pune 411 007 (India); Romani, R. W.; Den Hartog, P. R.; Kerr, M.; Michelson, P. F. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Ferrara, E. C.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement, LPCE UMR 6115 CNRS, F-45071 Orleans Cedex 02 (France); Johnston, S.; Keith, M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Epping, NSW 1710 (Australia); Saz Parkinson, P. M. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Wood, D. L. [Praxis Inc., Alexandria, VA 22303 (United States)

    2013-08-10

    Using the Giant Metrewave Radio Telescope, we performed deep observations to search for radio pulsations in the directions of unidentified Fermi-Large Area Telescope {gamma}-ray sources. We report the discovery of an eclipsing black-widow millisecond pulsar, PSR J1544+4937, identified with the uncataloged {gamma}-ray source FERMI J1544.2+4941. This 2.16 ms pulsar is in a 2.9 hr compact circular orbit with a very low mass companion (M{sub c} > 0.017M{sub Sun }). At 322 MHz this pulsar is found to be eclipsing for 13% of its orbit, whereas at 607 MHz the pulsar is detected throughout the low-frequency eclipse phase. Variations in the eclipse ingress phase are observed, indicating a clumpy and variable eclipsing medium. Moreover, additional short-duration absorption events are observed around the eclipse boundaries. Using the radio timing ephemeris we were able to detect {gamma}-ray pulsations from this pulsar, confirming it as the source powering the {gamma}-ray emission.

  20. Improving timing sensitivity in the microhertz frequency regime: limits from PSR J1713+0747 on gravitational waves produced by super-massive black-hole binaries

    Science.gov (United States)

    Perera, B. B. P.; Stappers, B. W.; Babak, S.; Keith, M. J.; Antoniadis, J.; Bassa, C. G.; Caballero, R. N.; Champion, D. J.; Cognard, I.; Desvignes, G.; Graikou, E.; Guillemot, L.; Janssen, G. H.; Karuppusamy, R.; Kramer, M.; Lazarus, P.; Lentati, L.; Liu, K.; Lyne, A. G.; McKee, J. W.; Osłowski, S.; Perrodin, D.; Sanidas, S. A.; Sesana, A.; Shaifullah, G.; Theureau, G.; Verbiest, J. P. W.; Taylor, S. R.

    2018-05-01

    We search for continuous gravitational waves (CGWs) produced by individual super-massive black-hole binaries (SMBHBs) in circular orbits using high-cadence timing observations of PSR J1713+0747. We observe this millisecond pulsar using the telescopes in the European Pulsar Timing Array (EPTA) with an average cadence of approximately 1.6 days over the period between April 2011 and July 2015, including an approximately daily average between February 2013 and April 2014. The high-cadence observations are used to improve the pulsar timing sensitivity across the GW frequency range of 0.008 - 5 μHz. We use two algorithms in the analysis, including a spectral fitting method and a Bayesian approach. For an independent comparison, we also use a previously published Bayesian algorithm. We find that the Bayesian approaches provide optimal results and the timing observations of the pulsar place a 95 per cent upper limit on the sky-averaged strain amplitude of CGWs to be ≲ 3.5 × 10-13 at a reference frequency of 1 μHz. We also find a 95 per cent upper limit on the sky-averaged strain amplitude of low-frequency CGWs to be ≲ 1.4 × 10-14 at a reference frequency of 20 nHz.

  1. PSR B0329+54: substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330 000 km

    Science.gov (United States)

    Popov, Mikhail V.; Bartel, Norbert; Gwinn, Carl R.; Johnson, Michael D.; Andrianov, Andrey; Fadeev, Evgeny; Joshi, Bhal Chandra; Kardashev, Nikolay; Karuppusamy, Ramesh; Kovalev, Yuri Y.; Kramer, Michael; Rudnitskiy, Alexey; Shishov, Vladimir; Smirnova, Tatiana; Soglasnov, Vladimir A.; Zensus, J. Anton

    2017-02-01

    We have resolved the scatter-broadened image of PSR B0329+54 and detected a substructure within it. These results are not influenced by any extended structure of a source but instead are directly attributed to the interstellar medium. We obtained these results at 324 MHz with the ground-space interferometer RadioAstron, which included the Space Radio Telescope, ground-based Westerbork Synthesis Radio Telescope and 64-m Kalyazin Radio Telescope on baseline projections up to 330 000 km in 2013 November 22 and 2014 January 1 to 2. At short 15 000 to 35 000 km ground-space baseline projections, the visibility amplitude decreases with baseline length, providing a direct measurement of the size of the scattering disc of 4.8 ± 0.8 mas. At longer baselines, no visibility detections from the scattering disc would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5 per cent of the maximum scattered around a mean and approximately constant up to 330 000 km. These visibilities reflect a substructure from scattering in the interstellar medium and offer a new probe of ionized interstellar material. The size of the diffraction spot near Earth is 17 000 ± 3 000 km. With the assumption of turbulent irregularities in the plasma of the interstellar medium, we estimate that the effective scattering screen is located 0.6 ± 0.1 of the distance from the Earth towards the pulsar.

  2. PSR B0329+54: Statistics of Substructure Discovered within the Scattering Disk on RadioAstron Baselines of up to 235,000 km

    Science.gov (United States)

    Gwinn, C. R.; Popov, M. V.; Bartel, N.; Andrianov, A. S.; Johnson, M. D.; Joshi, B. C.; Kardashev, N. S.; Karuppusamy, R.; Kovalev, Y. Y.; Kramer, M.; Rudnitskii, A. G.; Safutdinov, E. R.; Shishov, V. I.; Smirnova, T. V.; Soglasnov, V. A.; Steinmassl, S. F.; Zensus, J. A.; Zhuravlev, V. I.

    2016-05-01

    We discovered fine-scale structure within the scattering disk of PSR B0329+54 in observations with the RadioAstron ground-space radio interferometer. Here we describe this phenomenon, characterize it with averages and correlation functions, and interpret it as the result of decorrelation of the impulse-response function of interstellar scattering between the widely separated antennas. This instrument included the 10 m Space Radio Telescope, the 110 m Green Bank Telescope, the 14 × 25 m Westerbork Synthesis Radio Telescope, and the 64 m Kalyazin Radio Telescope. The observations were performed at 324 MHz on baselines of up to 235,000 km in 2012 November and 2014 January. In the delay domain, on long baselines the interferometric visibility consists of many discrete spikes within a limited range of delays. On short baselines it consists of a sharp spike surrounded by lower spikes. The average envelope of correlations of the visibility function shows two exponential scales, with characteristic delays of {τ }1=4.1+/- 0.3 μ {{s}} and {τ }2=23+/- 3 μ {{s}}, indicating the presence of two scales of scattering in the interstellar medium. These two scales are present in the pulse-broadening function. The longer scale contains 0.38 times the scattered power of the shorter one. We suggest that the longer tail arises from highly scattered paths, possibly from anisotropic scattering or from substructure at large angles.

  3. PSR B 1706-44 and the SNR G 343.1-2.3 as the remnants of a cavity supernova explosion

    Science.gov (United States)

    Bock, D. C.-J.; Gvaramadze, V. V.

    2002-11-01

    The possible association of the supernova remnant (SNR) G 343.1-2.3 with the pulsar PSR B 1706-44 (superposed on the arclike ``shell" of the SNR) has been questioned by some authors on the basis of an inconsistency between the implied and measured (scintillation) transverse velocities of the pulsar, the absence of any apparent interaction between the pulsar and the SNR's ``shell'', and some other indirect arguments. We suggest, however, that this association could be real if both objects are the remnants of a supernova (SN) which exploded within a mushroom-like cavity (created by the SN progenitor wind breaking out of the parent molecular cloud). This suggestion implies that the actual shape of the SNR's shell is similar to that of the well-known SNR VRO 42.05.01 and that the observed bright arc corresponds to the ``half'' of the SNR located inside the cloud. We report the discovery in archival radio data of an extended ragged radio arc to the southeast of the bright arc which we interpret as the ``half'' of the SN blast wave expanding in the intercloud medium.

  4. Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

    Science.gov (United States)

    Camilo, F.; Scholz, P.; Serylak, M.; Buchner, S.; Merryfield, M.; Kaspi, V. M.; Archibald, R. F.; Bailes, M.; Jameson, A.; van Straten, W.; Sarkissian, J.; Reynolds, J. E.; Johnston, S.; Hobbs, G.; Abbott, T. D.; Adam, R. M.; Adams, G. B.; Alberts, T.; Andreas, R.; Asad, K. M. B.; Baker, D. E.; Baloyi, T.; Bauermeister, E. F.; Baxana, T.; Bennett, T. G. H.; Bernardi, G.; Booisen, D.; Booth, R. S.; Botha, D. H.; Boyana, L.; Brederode, L. R. S.; Burger, J. P.; Cheetham, T.; Conradie, J.; Conradie, J. P.; Davidson, D. B.; De Bruin, G.; de Swardt, B.; de Villiers, C.; de Villiers, D. I. L.; de Villiers, M. S.; de Villiers, W.; De Waal, C.; Dikgale, M. A.; du Toit, G.; du Toit, L. J.; Esterhuyse, S. W. P.; Fanaroff, B.; Fataar, S.; Foley, A. R.; Foster, G.; Fourie, D.; Gamatham, R.; Gatsi, T.; Geschke, R.; Goedhart, S.; Grobler, T. L.; Gumede, S. C.; Hlakola, M. J.; Hokwana, A.; Hoorn, D. H.; Horn, D.; Horrell, J.; Hugo, B.; Isaacson, A.; Jacobs, O.; Jansen van Rensburg, J. P.; Jonas, J. L.; Jordaan, B.; Joubert, A.; Joubert, F.; Józsa, G. I. G.; Julie, R.; Julius, C. C.; Kapp, F.; Karastergiou, A.; Karels, F.; Kariseb, M.; Karuppusamy, R.; Kasper, V.; Knox-Davies, E. C.; Koch, D.; Kotzé, P. P. A.; Krebs, A.; Kriek, N.; Kriel, H.; Kusel, T.; Lamoor, S.; Lehmensiek, R.; Liebenberg, D.; Liebenberg, I.; Lord, R. T.; Lunsky, B.; Mabombo, N.; Macdonald, T.; Macfarlane, P.; Madisa, K.; Mafhungo, L.; Magnus, L. G.; Magozore, C.; Mahgoub, O.; Main, J. P. L.; Makhathini, S.; Malan, J. A.; Malgas, P.; Manley, J. R.; Manzini, M.; Marais, L.; Marais, N.; Marais, S. J.; Maree, M.; Martens, A.; Matshawule, S. D.; Matthysen, N.; Mauch, T.; McNally, L. D.; Merry, B.; Millenaar, R. P.; Mjikelo, C.; Mkhabela, N.; Mnyandu, N.; Moeng, I. T.; Mokone, O. J.; Monama, T. E.; Montshiwa, K.; Moss, V.; Mphego, M.; New, W.; Ngcebetsha, B.; Ngoasheng, K.; Niehaus, H.; Ntuli, P.; Nzama, A.; Obies, F.; Obrocka, M.; Ockards, M. T.; Olyn, C.; Oozeer, N.; Otto, A. J.; Padayachee, Y.; Passmoor, S.; Patel, A. A.; Paula, S.; Peens-Hough, A.; Pholoholo, B.; Prozesky, P.; Rakoma, S.; Ramaila, A. J. T.; Rammala, I.; Ramudzuli, Z. R.; Rasivhaga, M.; Ratcliffe, S.; Reader, H. C.; Renil, R.; Richter, L.; Robyntjies, A.; Rosekrans, D.; Rust, A.; Salie, S.; Sambu, N.; Schollar, C. T. G.; Schwardt, L.; Seranyane, S.; Sethosa, G.; Sharpe, C.; Siebrits, R.; Sirothia, S. K.; Slabber, M. J.; Smirnov, O.; Smith, S.; Sofeya, L.; Songqumase, N.; Spann, R.; Stappers, B.; Steyn, D.; Steyn, T. J.; Strong, R.; Struthers, A.; Stuart, C.; Sunnylall, P.; Swart, P. S.; Taljaard, B.; Tasse, C.; Taylor, G.; Theron, I. P.; Thondikulam, V.; Thorat, K.; Tiplady, A.; Toruvanda, O.; van Aardt, J.; van Balla, T.; van den Heever, L.; van der Byl, A.; van der Merwe, C.; van der Merwe, P.; van Niekerk, P. C.; van Rooyen, R.; van Staden, J. P.; van Tonder, V.; van Wyk, R.; Wait, I.; Walker, A. L.; Wallace, B.; Welz, M.; Williams, L. P.; Xaia, B.; Young, N.; Zitha, S.

    2018-04-01

    New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622–4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100× larger than during its dormant state. The X-ray flux one month after reactivation was at least 800× larger than during quiescence, and has been decaying exponentially on a 111 ± 19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3–6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6–8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.

  5. PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE γ-RAY PULSAR SEEN BY THE Fermi LAT

    Energy Technology Data Exchange (ETDEWEB)

    Allafort, A.; Bottacini, E.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J.; Chaves, R.C.G. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Rice University, Department of Physics and Astronomy, MS-108, P. O. Box 1892, Houston, TX 77251 (United States); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bonamente, E.; Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Caliandro, G. A. [Institut de Ciències de l' Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Chekhtman, A., E-mail: ltibaldo@slac.stanford.edu, E-mail: massimiliano.razzano@pi.infn.it [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030, resident at Naval Research Laboratory, Washington, DC 20375 (United States); and others

    2013-11-01

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The 'jump' was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 ± 0.08) × 10{sup –10} erg cm{sup –2} s{sup –1} to (6.86 ± 0.13) × 10{sup –10} erg cm{sup –2} s{sup –1}. Simultaneously, the frequency spindown rate increased from (7.8 ± 0.1) × 10{sup –13} Hz s{sup –1} to (8.1 ± 0.1) × 10{sup –13} Hz s{sup –1}. Significant (>5σ) changes in the pulse profile and marginal (<3σ) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at γ-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed γ-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

  6. Simultaneous Chandra and VLA Observations of the Transitional Millisecond Pulsar PSR J1023+0038: Anti-correlated X-Ray and Radio Variability

    Science.gov (United States)

    Bogdanov, Slavko; Deller, Adam T.; Miller-Jones, James C. A.; Archibald, Anne M.; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D’Angelo, Caroline

    2018-03-01

    We present coordinated Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations of the transitional millisecond pulsar PSR J1023+0038 in its low-luminosity accreting state. The unprecedented five hours of strictly simultaneous X-ray and radio continuum coverage for the first time unambiguously show a highly reproducible, anti-correlated variability pattern. The characteristic switches from the X-ray high mode into a low mode are always accompanied by a radio brightening with a duration that closely matches the X-ray low mode interval. This behavior cannot be explained by a canonical inflow/outflow accretion model where the radiated emission and the jet luminosity are powered by, and positively correlated with, the available accretion energy. We interpret this phenomenology as alternating episodes of low-level accretion onto the neutron star during the X-ray high mode that are interrupted by rapid ejections of plasma by the active rotation-powered pulsar, possibly initiated by a reconfiguration of the pulsar magnetosphere, that cause a transition to a less X-ray luminous mode. The observed anti-correlation between radio and X-ray luminosity has an additional consequence: transitional MSPs can make excursions into a region of the radio/X-ray luminosity plane previously thought to be occupied solely by black hole X-ray binary sources. This complicates the use of this luminosity relation for identifying candidate black holes, suggesting the need for additional discriminants when attempting to establish the true nature of the accretor.

  7. PSR J2021+4026 in the Gamma Cygni Region: The First Variable Gamma-Ray Pulsar Seen by the Fermi LAT

    Science.gov (United States)

    Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bellazzini, R.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; hide

    2013-01-01

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The "jump" was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33 plus or minus 0.08)×10(exp -10) erg cm(exp -2) s(exp -1) to (6.86 plus or minus 0.13)× 10 (exp -1)0 erg cm (exp -2) s(exp -1). Simultaneously, the frequency spindown rate increased from (7.8 plus or minus 0.1) × 10(exp -13) Hz s(exp -1) to (8.1 plus or minus 0.1) × 10(exp -1)3 Hz s(exp -1). Significant (greater than 5 sigma) changes in the pulse profile and marginal (less than 3 sigma) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at gamma-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed gamma-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

  8. The PaPsr1 and PaWhi2 genes are members of the regulatory network that connect stationary phase to mycelium differentiation and reproduction in Podospora anserina.

    Science.gov (United States)

    Timpano, Hélène; Chan Ho Tong, Laetitia; Gautier, Valérie; Lalucque, Hervé; Silar, Philippe

    2016-09-01

    In filamentous fungi, entrance into stationary phase is complex as it is accompanied by several differentiation and developmental processes, including the synthesis of pigments, aerial hyphae, anastomoses and sporophores. The regulatory networks that control these processes are still incompletely known. The analysis of the "Impaired in the development of Crippled Growth (IDC)" mutants of the model filamentous ascomycete Podospora anserina has already yielded important information regarding the pathway regulating entrance into stationary phase. Here, the genes affected in two additional IDC mutants are identified as orthologues of the Saccharomyces cerevisiae WHI2 and PSR1 genes, known to regulate stationary phase in this yeast, arguing for a conserved role of these proteins throughout the evolution of ascomycetes. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. PSR J2030+364I: Radio Discovery and Gamma-ray Study of a Middle-aged Pulsar in the Now Identified Fermi-LAT Source 1FGL J2030.0+3641

    Science.gov (United States)

    Camilo, F.; Kerr, M.; Ray, P. S.; Ransom, S. M.; Johnston, S.; Romani, R. W.; Parent, D.; Decesar, M. E.; Harding, A. K.; Donato, D.; hide

    2011-01-01

    In a radio search with the Green Bank Telescope of three unidentified low Galactic latitude Fermi-LAT sources, we have discovered the middle-aged pulsar J2030+3641, associated with IFGL J2030.0+3641 (2FGL J2030.0+3640). Following the detection of gamma-ray pulsations using a radio ephemeris, we have obtained a phase-coherent timing solution based on gamma-ray and radio pulse arrival times that spans the entire Fermi mission. With a rotation period of 0.28, spin-down luminosity of 3 x 10(exp 34) erg/s, and characteristic age of 0.5 Myr, PSR J2030+3641 is a middle-aged neutron star with spin parameters similar to those of the exceedingly gamma-ray-bright and radio-undetected Geminga. Its gamma-ray flux is 1 % that of Geminga, primarily because of its much larger distance, as suggested by the large integrated column density of free electrons, DM = 246 pc/cu cm. We fit the gamma-ray light curve, along with limited radio polarimetric constraints, to four geometrical models of magnetospheric emission, and while none of the fits have high significance some are encouraging and suggest that further refinements of these models may be worthwhile. We argue that not many more non-millisecond radio pulsars may be detected along the Galactic plane that are responsible for LAT sources, but that modified methods to search for gamma-ray pulsations should be productive - PSR J2030+364 I would have been found blindly in gamma rays if only > or approx. 0.8 GeV photons had been considered, owing to its relatively flat spectrum and location in a region of high soft background.

  10. Probing the properties of the pulsar wind via studying the dispersive effects in the pulses from the pulsar companion in a double neutron-star binary system

    Science.gov (United States)

    Yi, Shu-Xu; Cheng, K.-S.

    2017-12-01

    The velocity and density distribution of e± in the pulsar wind are crucial distinction among magnetosphere models, and contain key parameters determining the high-energy emission of pulsar binaries. In this work, a direct method is proposed, which might probe the properties of the wind from one pulsar in a double-pulsar binary. When the radio signals from the first-formed pulsar travel through the relativistic e± flow in the pulsar wind from the younger companion, the components of different radio frequencies will be dispersed. It will introduce an additional frequency-dependent time-of-arrival delay of pulses, which is function of the orbital phase. In this paper, we formulate the above-mentioned dispersive delay with the properties of the pulsar wind. As examples, we apply the formula to the double-pulsar system PSR J0737-3039A/B and the pulsar-neutron star binary PSR B1913+16. For PSR J0737-3039A/B, the time delay in 300 MHz is ≲ 10 μ s-1 near the superior conjunction, under the optimal pulsar wind parameters, which is approximately half of the current timing accuracy. For PSR B1913+16, with the assumption that the neutron-star companion has a typical spin-down luminosity of 1033 erg s-1, the time delay is as large as 10 - 20 μ s-1 in 300 MHz. The best timing precision of this pulsar is ∼ 5 μ s-1 in 1400 MHz. Therefore, it is possible that we can find this signal in archival data. Otherwise, we can set an upper limit on the spin-down luminosity. Similar analysis can be applied to other 11 known pulsar-neutron star binaries.

  11. DISCOVERY OF PULSED γ-RAYS FROM PSR J0034-0534 WITH THE FERMI LARGE AREA TELESCOPE: A CASE FOR CO-LOCATED RADIO AND γ-RAY EMISSION REGIONS

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bonamente, E.; Brigida, M.; Bruel, P.

    2010-01-01

    Millisecond pulsars (MSPs) have been firmly established as a class of γ-ray emitters via the detection of pulsations above 0.1 GeV from eight MSPs by the Fermi Large Area Telescope (LAT). Using 13 months of LAT data, significant γ-ray pulsations at the radio period have been detected from the MSP PSR J0034-0534, making it the ninth clear MSP detection by the LAT. The γ-ray light curve shows two peaks separated by 0.274 ± 0.015 in phase which are very nearly aligned with the radio peaks, a phenomenon seen only in the Crab pulsar until now. The ≥0.1 GeV spectrum of this pulsar is well fit by an exponentially cutoff power law with a cutoff energy of 1.8 ± 0.6 ± 0.1 GeV and a photon index of 1.5 ± 0.2 ± 0.1, first errors are statistical and second are systematic. The near-alignment of the radio and γ-ray peaks strongly suggests that the radio and γ-ray emission regions are co-located and both are the result of caustic formation.

  12. Selection of detailed items for periodic safety review on PWR radwaste management system

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K. B.; Ahn, Y. S.; Park, Y. S.; Kim, S. H.; Kim, J. T. [Korea Hydric and Nuclear Power Company, Taejon (Korea, Republic of)

    2003-10-01

    Selection of detailed-items for Periodic Safety Review on PWR radwaste management system, the main component could be faithfully clarified according to the purpose of establishment on each system and basic purpose. It is proper to select detailed-items those of radioactivities in the reactor coolant activity levels and the released volume of liquid and gaseous radioactive material on safety performance. It's also proper to select solid radwaste production quantities as detailed-item that it would be predict the next ten years trends after PSR.

  13. A Photo Storm Report Mobile Application, Processing/Distribution System, and AWIPS-II Display Concept

    Science.gov (United States)

    Longmore, S. P.; Bikos, D.; Szoke, E.; Miller, S. D.; Brummer, R.; Lindsey, D. T.; Hillger, D.

    2014-12-01

    The increasing use of mobile phones equipped with digital cameras and the ability to post images and information to the Internet in real-time has significantly improved the ability to report events almost instantaneously. In the context of severe weather reports, a representative digital image conveys significantly more information than a simple text or phone relayed report to a weather forecaster issuing severe weather warnings. It also allows the forecaster to reasonably discern the validity and quality of a storm report. Posting geo-located, time stamped storm report photographs utilizing a mobile phone application to NWS social media weather forecast office pages has generated recent positive feedback from forecasters. Building upon this feedback, this discussion advances the concept, development, and implementation of a formalized Photo Storm Report (PSR) mobile application, processing and distribution system and Advanced Weather Interactive Processing System II (AWIPS-II) plug-in display software.The PSR system would be composed of three core components: i) a mobile phone application, ii) a processing and distribution software and hardware system, and iii) AWIPS-II data, exchange and visualization plug-in software. i) The mobile phone application would allow web-registered users to send geo-location, view direction, and time stamped PSRs along with severe weather type and comments to the processing and distribution servers. ii) The servers would receive PSRs, convert images and information to NWS network bandwidth manageable sizes in an AWIPS-II data format, distribute them on the NWS data communications network, and archive the original PSRs for possible future research datasets. iii) The AWIPS-II data and exchange plug-ins would archive PSRs, and the visualization plug-in would display PSR locations, times and directions by hour, similar to surface observations. Hovering on individual PSRs would reveal photo thumbnails and clicking on them would display the

  14. Robustness Area Technique Developing Guidelines for Power System Restoration

    Directory of Open Access Journals (Sweden)

    Paulo Murinelli Pesoti

    2017-01-01

    Full Text Available This paper proposes a novel energy based technique called the Robustness Area (RA technique that measures power system robustness levels, as a helper for planning Power System Restorations (PSRs. The motivation is on account of the latest blackouts in Brazil, where the local Independent System Operator (ISO encountered difficulties related to circuit disconnections during the restoration. The technique identifies vulnerable and robust buses, pointing out system areas that should be firstly reinforced during PSR, in order to enhance system stability. A Brazilian power system restoration area is used to compare the guidelines adopted by the ISO with a more suitable new plan indicated by the RA tool. Active power and reactive power load margin and standing phase angle show the method efficiency as a result of a well balanced system configuration, enhancing the restoration performance. Time domain simulations for loop closures and severe events also show the positive impact that the proposed tool brings to PSRs.

  15. THE PLERIONIC SUPERNOVA REMNANT G21.5-0.9 POWERED BY PSR J1833-1034: NEW SPECTROSCOPIC AND IMAGING RESULTS REVEALED WITH THE CHANDRA X-RAY OBSERVATORY

    International Nuclear Information System (INIS)

    Matheson, Heather; Safi-Harb, Samar

    2010-01-01

    In 1999, the Chandra X-ray Observatory revealed a 150'' radius halo surrounding the 40'' radius pulsar wind nebula (PWN) G21.5-0.9. A 2005 imaging study of G21.5-0.9 showed that the halo is limb-brightened and suggested that this feature is a candidate for the long-sought supernova remnant (SNR) shell. We present a spectral analysis of SNR G21.5-0.9, using the longest effective observation to date (578.6 ks with the Advanced CCD Imaging Spectrometer (ACIS) and 278.4 ks with the High-Resolution Camera (HRC)) to study unresolved questions about the spectral nature of remnant features, such as the limb brightening of the X-ray halo and the bright knot in the northern part of the halo. The Chandra analysis favors the non-thermal interpretation of the limb. Its spectrum is fit well with a power-law model with a photon index Γ = 2.13 (1.94-2.33) and a luminosity of L x (0.5-8 keV) = (2.3 ± 0.6) x 10 33 erg s -1 (at an assumed distance of 5.0 kpc). An srcut model was also used to fit the spectrum between the radio and X-ray energies. While the absence of a shell in the radio still prohibits constraining the spectrum at radio wavelengths, we assume a range of spectral indices to infer the 1 GHz flux density and the rolloff frequency of the synchrotron spectrum in X-rays and find that the maximum energy to which electrons are accelerated at the shock ranges from ∼60 to 130 TeV (B/10 μG) -1/2 , where B is the magnetic field in units of μG. For the northern knot, we constrain previous models and find that a two-component power-law (or srcut) + pshock model provides an adequate fit, with the pshock model requiring a very low ionization timescale and solar abundances for Mg and Si. Our spectroscopic study of PSR J1833-1034, the highly energetic pulsar powering G21.5-0.9, shows that its spectrum is dominated by hard non-thermal X-ray emission with some evidence of a thermal component that represents ∼9% of the observed non-thermal emission and that suggests non

  16. Development of Safety Assessment Information System (SAIS)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byung Shik; Lee, Kyung Jin; Lee, Byung Chul [FNC Tech. Co. Ltd. SNU, Seoul (Korea, Republic of); Song, Tae Young; Lee, Chang Ho [KHNP, Daejeon (Korea, Republic of)

    2007-10-15

    Many reports and documents about nuclear power plant safety analysis like a Periodic Safe Review (PSR), Periodic Safety Analysis (PSA) and Severe Accident Management Guideline (SAMG) come to be drawn up from KHNP. Since these are not arranged easy to look up, the systematic arrangement of data was necessary. The solution against hereupon is to store database, and it was developed with the name, SAIS, by FNC Tech. Co. together with NETEC KHNP. In this web program it is easy to manage (registration, search and statistics) data. And the authorized user can approach this system. This was developed, and was verified under the development environment of; - Web Server : Apache 2.2.5 - Program Language : PHP 5.2 - DBMS : Oracle 10g.

  17. Development of Safety Assessment Information System (SAIS)

    International Nuclear Information System (INIS)

    Park, Byung Shik; Lee, Kyung Jin; Lee, Byung Chul; Song, Tae Young; Lee, Chang Ho

    2007-01-01

    Many reports and documents about nuclear power plant safety analysis like a Periodic Safe Review (PSR), Periodic Safety Analysis (PSA) and Severe Accident Management Guideline (SAMG) come to be drawn up from KHNP. Since these are not arranged easy to look up, the systematic arrangement of data was necessary. The solution against hereupon is to store database, and it was developed with the name, SAIS, by FNC Tech. Co. together with NETEC KHNP. In this web program it is easy to manage (registration, search and statistics) data. And the authorized user can approach this system. This was developed, and was verified under the development environment of; - Web Server : Apache 2.2.5 - Program Language : PHP 5.2 - DBMS : Oracle 10g

  18. Development of a Safety Assessment Information System for the Management of Periodic Safety Assessment Activities

    International Nuclear Information System (INIS)

    Song, Tae Young

    2007-01-01

    At present, the 10-year Periodic Safety Review(PSR) has been performing to confirm all the aspects of safety issues for all the operating plants in compliance with domestic nuclear law of article 23, subarticle 3. For each plant, in addition, Probabilistic Safety Assessment(PSA) and Severe Accident Management Guideline(SAMG) are being implemented and revised periodically to reflect the latest safety level according to principle fulfillment of severe accident policy statement. The assessment reports, as one of outcomes from these activities, are submitted into and reviewed by domestic regulatory body. During reviewing (in-office duty) and licensing (regulatory duty) process, a large number of outcomes of which most are the formal technical reports and licensing materials, are inevitably produced. Moreover, repeated review process over the plants can make them accumulated and produce a variety of documents additionally. This circumstance motivates to develop effective tool or system for the management of these reports and related technical documents for the future use in licensing process and for subsequent plant assessments. This paper presents the development status of Safety Assessment Information System(SAIS) which manages safety-related documents of PSR, PSA and SAMG for practical use for experienced engineers in charge of these areas

  19. Development of a Safety Assessment Information System for the Management of Periodic Safety Assessment Activities

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tae Young [Nuclear Engineering and Technology Institute, Daejeon (Korea, Republic of)

    2007-07-01

    At present, the 10-year Periodic Safety Review(PSR) has been performing to confirm all the aspects of safety issues for all the operating plants in compliance with domestic nuclear law of article 23, subarticle 3. For each plant, in addition, Probabilistic Safety Assessment(PSA) and Severe Accident Management Guideline(SAMG) are being implemented and revised periodically to reflect the latest safety level according to principle fulfillment of severe accident policy statement. The assessment reports, as one of outcomes from these activities, are submitted into and reviewed by domestic regulatory body. During reviewing (in-office duty) and licensing (regulatory duty) process, a large number of outcomes of which most are the formal technical reports and licensing materials, are inevitably produced. Moreover, repeated review process over the plants can make them accumulated and produce a variety of documents additionally. This circumstance motivates to develop effective tool or system for the management of these reports and related technical documents for the future use in licensing process and for subsequent plant assessments. This paper presents the development status of Safety Assessment Information System(SAIS) which manages safety-related documents of PSR, PSA and SAMG for practical use for experienced engineers in charge of these areas.

  20. A millisecond pulsar in a stellar triple system.

    Science.gov (United States)

    Ransom, S M; Stairs, I H; Archibald, A M; Hessels, J W T; Kaplan, D L; van Kerkwijk, M H; Boyles, J; Deller, A T; Chatterjee, S; Schechtman-Rook, A; Berndsen, A; Lynch, R S; Lorimer, D R; Karako-Argaman, C; Kaspi, V M; Kondratiev, V I; McLaughlin, M A; van Leeuwen, J; Rosen, R; Roberts, M S E; Stovall, K

    2014-01-23

    Gravitationally bound three-body systems have been studied for hundreds of years and are common in our Galaxy. They show complex orbital interactions, which can constrain the compositions, masses and interior structures of the bodies and test theories of gravity, if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, PSR B1620-26 (refs 7, 8; with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multiwavelength observations of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar M[Symbol: see text](1.4378(13), where M[Symbol: see text]is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15)M[Symbol: see text] and 0.4101(3))M[Symbol: see text], as well as the inclinations of the orbits (both about 39.2°). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity.

  1. An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system.

    Science.gov (United States)

    Burgay, M; D'Amico, N; Possenti, A; Manchester, R N; Lyne, A G; Joshi, B C; McLaughlin, M A; Kramer, M; Sarkissian, J M; Camilo, F; Kalogera, V; Kim, C; Lorimer, D R

    2003-12-04

    The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe).

  2. Treatment of Mesh Skin Grafted Scars Using a Plasma Skin Regeneration System

    Directory of Open Access Journals (Sweden)

    Takamitsu Higashimori

    2010-01-01

    Full Text Available Objectives. Several modalities have been advocated to treat traumatic scars, including surgical techniques and laser resurfacing. Recently, a plasma skin regeneration (PSR system has been investigated. There are no reports on plasma treatment of mesh skin grafted scars. The objective of our study is to evaluate the effectiveness and complications of plasma treatment of mesh skin grafted scars in Asian patients. Materials and Methods. Four Asian patients with mesh skin grafted scars were enrolled in the study. The plasma treatments were performed at monthly intervals with PSR, using energy settings of 3 to 4 J. Improvement was determined by patient questionnaires and physician evaluation of digital photographs taken prior to treatment and at 3 months post treatment. The patients were also evaluated for any side effects from the treatment. Results. All patients showed more than 50% improvement. The average pain score on a 10-point scale was 6.9 +/− 1.2 SD and all patients tolerated the treatments. Temporary, localized hypopigmentation was observed in two patients. Hyperpigmentation and worsening of scarring were not observed. Conclusions. Plasma treatment is clinically effective and is associated with minimal complications when used to treat mesh skin grafted scars in Asian patients.

  3. The Argonne beamline-B telescope control system: A study of adaptability

    International Nuclear Information System (INIS)

    Fuka, M.A.; Clout, P.N.; Conley, A.P.; Hill, J.O.; Rothrock, R.B.; Trease, L.L.; Zander, M.E.

    1987-01-01

    A beam-expanding telescope to study high-precision H - particle optics and beam sensing was designed by the Accelerator Technology Division at Los Alamos National Laboratory and will be installed on beamline-B at Argonne National Laboratory. The control system for this telescope was developed in a relatively short period of time using experience gained from building the Proton Storage Ring (PSR) control system. The designers modified hardware and software to take advantage of new technology as well as to meet the requirements of the new system. This paper discusses lessons learned in the process of adapting hardware and software from an existing control system to one with rather different requirements

  4. Institutionalization of safety re-assessment system for operating nuclear power plants

    International Nuclear Information System (INIS)

    Kim, H. J.; Cho, J. C.; Min, B. K.; Park, J. S.; Jung, H. D.; Oh, K. M.; Kim, W. K.; Lim, J. H.

    1999-01-01

    In this study, in-depth reviews of the foreign countries' experiences and practices in applications of the periodic safety review (PSR), backfitting and license renewal systems as well as the current status of nuclear power safety assurance programs and activities in Korea have been performed to investigate the necessity and feasibility of the application of the systems for the domestic operating nuclear power plants and to establish effective strategy and methodology for the institutionalization of a periodic safety re-assessment system appropriate to both the domestic and international nuclear power environments by incorporating the PSR with the backfitting and license renewal systems. For these purposes, the regulatory policy, fundamental principles and detailed requirements for the institutionalization of the safety re-assessment system and the effective measures for active implementation of the backfitting program have been developed and then a comparative study of benefits and shortcomings has been conducted for the three different models of the periodic safety re-assessment system incorporated with either the license renewal or life extension process, which have been considered as practicable ones in the domestic situation. The model chosen in this study as the most appropriate safety re-assessment system is the one that the re-assessments are performed at the interval of ten years throughout the service life of nuclear power plant and the ten-year license renewal or life extension after the expiration of design life can be permitted based on the regulatory review of the re-assessment results and follow-up measures. Finally, this paper has discussed on the details of the requirements, approach and procedures established for the institutionalization of the periodic safety re-assessment system chosen as the most appropriate one for domestic applications

  5. The European Emission Trading System and competition. Anticompetitive measures beyond reach? An assessment of the grandfathering allocation method and the Performance Standard Rate system

    International Nuclear Information System (INIS)

    Weishaar, S.

    2006-10-01

    The center piece of the European Climate Change Program is the ambitious Greenhouse Gas Emissions Trading Scheme (EU ETS, Directive 2003/87/EC) which helps Member States to fulfill their Kyoto commitments. It particularly facilitates the old EU 15 Member States to make progress towards meeting their particular greenhouse gas emissions reduction goals committed under the Burden Sharing Agreement. EU Member States have developed national greenhouse gas allowances allocation plans and distributed these allowances to around 5000 operators with approximately 12.000 installations. Differences between allocations can give rise to severe anticompetitive effects. Undue interventions by Member States are largely contained through the application of the four freedoms, while EC Competition law (Articles 81 and 82) is geared to the containment of competitive distortions arising in particular from undue behavior of firms. State involvement in infringements is addressed through Articles 87 (State aid) and 86 (public undertakings) and the 'joint application doctrine' (Articles 10(2), 3(g), 81 and 82) which was developed by the ECJ upon recognition that State measures can undermine the effectiveness of the EC Treaty. The paper examines how anticompetitive distortions originating from Member State action under National Allocation Plans in general and by application of (historical) grandfathering and the (hypothetical) Performance Standard Rate (PSR) allocation format in particular are dealt with under European competition law rules. The PSR System is a relative benchmark system with an intended cap for all participants but without a cap for individual operators. This alternative approach has been developed and is actually in use for the Dutch NOx Emission Trading System. An interdisciplinary industrial economic and competition law framework is chosen to formulate an economic critique. After the introductory part the anticompetitive effects originating in State measures are examined

  6. A mysterious dust clump in a disk around an evolved binary star system.

    Science.gov (United States)

    Jura, M; Turner, J

    1998-09-10

    The discovery of planets in orbit around the pulsar PSR1257+12 shows that planets may form around post-main-sequence stars. Other evolved stars, such as HD44179 (an evolved star which is part of the binary system that has expelled the gas and dust that make the Red Rectangle nebula), possess gravitationally bound orbiting dust disks. It is possible that planets might form from gravitational collapse in such disks. Here we report high-angular-resolution observations at millimetre and submillimetre wavelengths of the dusk disk associated with the Red Rectangle. We find a dust clump with an estimated mass near that of Jupiter in the outer region of the disk. The clump is larger than our Solar System, and far beyond where planet formation would normally be expected, so its nature is at present unclear.

  7. Mined Geologic Disposal System Requirements Document

    International Nuclear Information System (INIS)

    1994-03-01

    This Mined Geologic Disposal System Requirements Document (MGDS-RD) describes the functions to be performed by, and the requirements for, a Mined Geologic Disposal System (MGDS) for the permanent disposal of spent nuclear fuel (SNF) (including SNF loaded in multi-purpose canisters (MPCs)) and commercial and defense high-level radioactive waste (HLW) in support of the Civilian Radioactive Waste Management System (CRWMS). The purpose of the MGDS-RD is to define the program-level requirements for the design of the Repository, the Exploratory Studies Facility (ESF), and Surface Based Testing Facilities (SBTF). These requirements include design, operation, and decommissioning requirements to the extent they impact on the physical development of the MGDS. The document also presents an overall description of the MGDS, its functions (derived using the functional analysis documented by the Physical System Requirements (PSR) documents as a starting point), its segments as described in Section 3.1.3, and the requirements allocated to the segments. In addition, the program-level interfaces of the MGDS are identified. As such, the MGDS-RD provides the technical baseline for the design of the MGDS

  8. Multi-Planetary Systems: Observations and Models of Dynamical Interactions

    Science.gov (United States)

    Lissauer, Jack J.

    2018-01-01

    More than 600 multi-planet systems are known. The vast majority of these systems have been discovered by NASA's Kepler spacecraft, but dozens were found using the Doppler technique, the first multi-exoplanet system was identified through pulsar timing, and the most massive system has been found using imaging. More than one-third of the 4000+ planet candidates found by NASA's Kepler spacecraft are associated with target stars that have more than one planet candidate, and the large number of such Kepler "multis" tells us that flat multiplanet systems like our Solar System are common. Virtually all of Kepler candidate multis are stable, as tested by numerical integrations that assume a physically motivated mass-radius relationship. Statistical studies performed on these candidate systems reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness. The characteristics of several of the most interesting confirmed multi-exoplanet systems will also be discussed.HR 8799's four massive planets orbit tens of AU from their host star and travel on nearly circular orbits. PSR B1257+12 has three much smaller planets orbiting close to a neutron star. Both represent extremes and show that planet formation is a robust process that produces a diversity of outcomes. Although both exomoons and Trojan (triangle Lagrange point) planets have been searched for, neither has yet been found.

  9. Monitored Retrievable Storage System Requirements Document

    International Nuclear Information System (INIS)

    1994-03-01

    This Monitored Retrievable Storage System Requirements Document (MRS-SRD) describes the functions to be performed and technical requirements for a Monitored Retrievable Storage (MRS) facility subelement and the On-Site Transfer and Storage (OSTS) subelement. The MRS facility subelement provides for temporary storage, at a Civilian Radioactive Waste Management System (CRWMS) operated site, of spent nuclear fuel (SNF) contained in an NRC-approved Multi-Purpose Canister (MPC) storage mode, or other NRC-approved storage modes. The OSTS subelement provides for transfer and storage, at Purchaser sites, of spent nuclear fuel (SNF) contained in MPCs. Both the MRS facility subelement and the OSTS subelement are in support of the CRWMS. The purpose of the MRS-SRD is to define the top-level requirements for the development of the MRS facility and the OSTS. These requirements include design, operation, and decommissioning requirements to the extent they impact on the physical development of the MRS facility and the OSTS. The document also presents an overall description of the MRS facility and the OSTS, their functions (derived by extending the functional analysis documented by the Physical System Requirements (PSR) Store Waste Document), their segments, and the requirements allocated to the segments. In addition, the top-level interface requirements of the MRS facility and the OSTS are included. As such, the MRS-SRD provides the technical baseline for the MRS Safety Analysis Report (SAR) design and the OSTS Safety Analysis Report design

  10. Study on the Coupling Coordination Degree between Metropolitan Economic System and Water Environmental System - Taking Beijing as an Example

    Directory of Open Access Journals (Sweden)

    Chen Ming

    2017-01-01

    Full Text Available The generation of metropolis is the inevitable outcome of the development of urbanization to a certain stage. The economy and society of metropolis are in the rapid development, but this process brings great pressure to the ecological environment, especially the water resources environment at the same time. In this paper, the relationship between metropolitan economic system and water environmental system is deeply studied, and the concept of “coupling” is introduced. Based on the framework of “pressure-state-response” (PSR, 12 detailed indexes, such as total population and water consumption per ten thousand Yuan GDP, were selected to construct four subsystems. The coordination degree measurement model has been used to calculate the degree of coupling between the economic system and water environmental system. On this basis, the following conclusions are drawn through the example of Beijing city: (1 In the process of metropolitan development, the economic system and the water environmental system are interrelated and there exist a complex coupling mechanism. (2 With the adjustment of economic structure and the progress of technology, the coupling index between the metropolitan economic system and the water environmental system has been increasing, and this process shows an upward trend

  11. Systems

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Papers in this session describe the concept of mined geologic disposal system and methods for ensuring that the system, when developed, will meet all technical requirements. Also presented in the session are analyses of system parameters, such as cost and nuclear criticality potential, as well as a technical analysis of a requirement that the system permit retrieval of the waste for some period of time. The final paper discusses studies under way to investigate technical alternatives or complements to the mined geologic disposal system. Titles of the presented papers are: (1) Waste Isolation System; (2) Waste Isolation Economics; (3) BWIP Technical Baseline; (4) Criticality Considerations in Geologic Disposal of High-Level Waste; (5) Retrieving Nuclear Wastes from Repository; (6) NWTS Programs for the Evaluation of Technical Alternatives or Complements to Mined Geologic Repositories - Purpose and Objectives

  12. systems

    Directory of Open Access Journals (Sweden)

    Alexander Leonessa

    2000-01-01

    Full Text Available A nonlinear robust control-system design framework predicated on a hierarchical switching controller architecture parameterized over a set of moving nominal system equilibria is developed. Specifically, using equilibria-dependent Lyapunov functions, a hierarchical nonlinear robust control strategy is developed that robustly stabilizes a given nonlinear system over a prescribed range of system uncertainty by robustly stabilizing a collection of nonlinear controlled uncertain subsystems. The robust switching nonlinear controller architecture is designed based on a generalized (lower semicontinuous Lyapunov function obtained by minimizing a potential function over a given switching set induced by the parameterized nominal system equilibria. The proposed framework robustly stabilizes a compact positively invariant set of a given nonlinear uncertain dynamical system with structured parametric uncertainty. Finally, the efficacy of the proposed approach is demonstrated on a jet engine propulsion control problem with uncertain pressure-flow map data.

  13. Civilian Radioactive Waste Management System Requirements Document

    International Nuclear Information System (INIS)

    1992-12-01

    This document specifies the top-level requirements for the Civilian Radioactive Waste Management System (CRWMS). The document is referred to herein as the CRD, for CRWMS Requirements document. The OCRWM System Engineering Management Plan (SEMP) establishes the technical document hierarchy (hierarchy of technical requirements and configuration baseline documents) for the CRWMS program. The CRD is the top-level document in this hierarchy. The immediate subordinate documents are the System Requirements Documents (SRDS) for the four elements of the CRWMS and the Interface Specification (IFS). The four elements of the CRWMS are the Waste Acceptance System, the Transportation System, the Monitored Retrievable Storage (MRS) System and the Mined Geologic Disposal System (MGDS). The Interface Specification describes the six inter-element interfaces between the four elements. This hierarchy establishes the requirements to be addressed by the design of the system elements. Many of the technical requirements for the CRWMS are documented in a variety of Federal regulations, DOE directives and other Government documentation. It is the purpose of the CRD to establish the technical requirements for the entire program. In doing so, the CRD summarizes source documentation for requirements that must be addressed by the program, specifies particular requirements, and documents derived requirements that are not covered in regulatory and other Government documentation, but are necessary to accomplish the mission of the CRWMS. The CRD defines the CRWMS by identifying the top-level functions the elements must perform (These top-level functions were derived using functional analysis initially documented in the Physical System Requirements (PSR) documents). The CRD also defines the top-level physical architecture of the system and allocates the functions and requirements to the architectural elements of the system

  14. "Calibration" system for spectral measurements and its experimental results

    Science.gov (United States)

    Bruchkouskaya, Sviatlana I.; Katkovsky, Leonid V.; Belyaev, Boris I.; Malyshev, Vladislav B.

    2017-04-01

    "Calibration" system has been developed at A. N. Sevchenko Research Institute of Applied Physical Problems of the Belarusian State University. It was designed for measuring the characteristics of spectral reflectance of all types of natural surfaces (test sites) in ground conditions or on board of aircraft carriers and has the following components: - Photospectroradiometr (PhSR) of high resolution with a range of 400-900 nm, equipped with a digital time-lapse video system; - Two-channel modular spectroradiometer (TMS) with a range of 400-900 nm, designed for simultaneous measurements of reflected light brightness of the underlying surface and the incident radiation from the upper hemisphere; - Two portable spectroradiometers (PSR-700 and PSR-1300) with a spectral range 800-1500 nm; 1200-2500 nm; - Scanning solar spectropolarimeter (SSP-600) with a range of 350-950 nm for measurements of direct sunlight and scattered by the atmosphere at different angles; "Calibration" system provides spectral resolution of 5.2 nm in a range of 400-900 nm, 10 nm in a range of 800-1500 nm and 15 nm in a range of 1200-2500 nm. Measurements of the optical characteristics of solar radiation (for determining parameters of the atmosphere) and that of underlying surface are synchronous. There is also a set of special nozzles for measurements of spectral brightness coefficients, polarization characteristics and spectral albedo. Spectra and images are geotagged to the navigation data (time, GPS). For the measurements of spectral reflection dependencies within "Monitoring-SG" framework expeditions to the Kuril Islands, Kursk aerospace test site and Kamchatka Peninsula were conducted in 2015 and 2016. The spectra of different underlying surfaces have been obtained: soils, plants and water objects, sedimentary and volcanic rocks. These surveys are a valuable material for further researches and selection of test facilities for flight calibration of space imaging systems. Information obtained

  15. Domestic Regulation for Periodic Safety Review of Nuclear Power Plants

    International Nuclear Information System (INIS)

    Kim, Daesik; Ahn, Seunghoon; Auh, Geunsun; Lee, Jonghyeok

    2015-01-01

    The so-called Periodic Safety Review (PSR) has been carried out such safety assessment throughout its life, on a periodic basis. In January 2001, the Atomic Energy Act and related regulations were amended to adopt the PSR institutional scheme from IAEA Nuclear Safety Guide 50-SG-O12. At that time the safety assessment was made to review the plant safety on 10 safety factors, such as aging management and emergency planning, where the safety factor indicates the important aspects of safety of an operating NPP to be addressed in the PSR. According to this legislation, the domestic utility, the KHNP has conducted the PSR for the operating NPP of 10 years coming up from operating license date, starting since May 2000. Some revisions in the PSR rule were made to include the additional safety factors last year. This paper introduces the current status of the PSR review and regulation, in particular new safety factors and updated technical regulation. Comprehensive safety assessment for Korea Nuclear Power Plants have performed a reflecting design and procedure changes and considering the latest technology every 10 years. This paper also examined the PSR system changes in Korea. As of July 2015, reviews for PSR of 18 units have been completed, with 229 nuclear safety improvement items. And implementation have been completed for 165 of them. PSR system has been confirmed that it has contributed to improvement of plant safety. In addition, this paper examined the PSR system change in Korea

  16. SYSTEM

    Directory of Open Access Journals (Sweden)

    K. Swarnalatha

    2013-01-01

    Full Text Available Risk analysis of urban aquatic systems due to heavy metals turns significant due to their peculiar properties viz. persis tence, non-degradab ility, toxicity, and accumulation. Akkulam Veli (AV, an urba n tropical lake in south India is subjected to various environmental stresses due to multiple waste discharge, sand mining, developmental activities, tour ism related activitie s etc. Hence, a comprehensive approach is adopted for risk assessment using modified degree of contamination factor, toxicity units based on numerical sediment quality guidelines (SQGs, and potentialecological risk indices. The study revealed the presence of toxic metals such as Cr, C d, Pb and As and the lake is rated under ‘low ecological risk’ category.

  17. Monitored Retrievable Storage System Requirements Document. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    This Monitored Retrievable Storage System Requirements Document (MRS-SRD) describes the functions to be performed and technical requirements for a Monitored Retrievable Storage (MRS) facility subelement and the On-Site Transfer and Storage (OSTS) subelement. The MRS facility subelement provides for temporary storage, at a Civilian Radioactive Waste Management System (CRWMS) operated site, of spent nuclear fuel (SNF) contained in an NRC-approved Multi-Purpose Canister (MPC) storage mode, or other NRC-approved storage modes. The OSTS subelement provides for transfer and storage, at Purchaser sites, of spent nuclear fuel (SNF) contained in MPCs. Both the MRS facility subelement and the OSTS subelement are in support of the CRWMS. The purpose of the MRS-SRD is to define the top-level requirements for the development of the MRS facility and the OSTS. These requirements include design, operation, and decommissioning requirements to the extent they impact on the physical development of the MRS facility and the OSTS. The document also presents an overall description of the MRS facility and the OSTS, their functions (derived by extending the functional analysis documented by the Physical System Requirements (PSR) Store Waste Document), their segments, and the requirements allocated to the segments. In addition, the top-level interface requirements of the MRS facility and the OSTS are included. As such, the MRS-SRD provides the technical baseline for the MRS Safety Analysis Report (SAR) design and the OSTS Safety Analysis Report design.

  18. The Dynamic Coordinated Development of a Regional Environment-Tourism-Economy System: A Case Study from Western Hunan Province, China

    Directory of Open Access Journals (Sweden)

    Yaoqing Yuan

    2014-08-01

    Full Text Available Based on regional coordination theory and system theory, the authors constructed an evaluation index system for the coordinated development of a regional environment-tourism-economy system with a pressure-state-response (PSR model. With a coordinated development model, it further empirically analyzed the coordinated development state of an environment-tourism-economy system in western Hunan from 2001 to 2012. The results showed that, although this environment-tourism-economy system failed to achieve a high benefit index, inter-subsystem coupling extent, and coordinated development index, the three indices presented an increasing overall trend. This outcome suggested that the sub-systems in this system were developing towards their optimal proportions: the development of these sub-systems (environmental, tourism, and economic was unbalanced in western Hunan. The environment therein sees only slow development although provided with a favorable ecological foundation. Economic development, which has long been lagging, acted as the main factor restricting the coordinated development of a regional environment-tourism-economy system. To promote its coordinated development in western Hunan, the following recommendations were proposed: strengthen the prediction and warnings on the evolution of the whole system; optimize the industry’s structure; reinforce environmental management.

  19. PSR1987A: the case for strange-quark stars

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1989-01-01

    The new fast pulsar observed in the remnant of SN1987A, together with other considerations, provide evidence that there are two types of collapsed stars: neutron stars, having moderate central densities and subject to the usual mass constraint, and strange-quark-matter stars. We show that (i) all known pulsar masses and frequencies, with the exception of the new one, can be accounted for by plausible neutron star models; (ii) no known neutron star model can withstand the fast rotation of the new pulsar unless the central energy density is ∼ 15 that of normal nuclei, at which densities hadrons cannot plausibly exist as constituents; and (iii) if strange-quark matter is the true ground state of the strong interactions, strange-quark stars can sustain the high rotation imputed to the new pulsar. In the absence of another plausible structure that can withstand the fast rotation, we provisionally infer that the new pulsar is such a star. (author)

  20. SMEX04 Aircraft Polarimetric Scanning Radiometer (PSR) Data, Arizona

    Data.gov (United States)

    National Aeronautics and Space Administration — Notice to Data Users: The documentation for this data set was provided solely by the Principal Investigator(s) and was not further developed, thoroughly reviewed, or...

  1. Phase-Resolved Spectra of PSR B0525+21 and PSR B2020+28 JL ...

    Indian Academy of Sciences (India)

    J. L. Chen1,2, H. G. Wang3,∗. & N. Wang1. 1Xinjiang Astronomical Observatory, 150, Science-1 Street, Urumqi, Xinjiang 830011, China. 2Graduate University of the Chinese Academy of Scienes, 19A Yuquan Road, Beijing. 100049, China. 3Center for Astrophysics, Guangzhou University, Guangzhou 510006, China. ∗.

  2. Efeitos de sistemas de preparo nas propriedades físicas de um Latossolo Vermelho distrófico Effects of tillage systems on the soil physical properties of a dystrophic Red Latosol

    Directory of Open Access Journals (Sweden)

    Karina Maria Vieira Cavalieri

    2006-02-01

    Full Text Available Os sistemas de preparo do solo e o manejo dos resíduos culturais assumem fundamental importância para a sustentabilidade dos sistemas de produção de mandioca nos solos de textura média a arenosa da região Noroeste do Estado do Paraná. O objetivo deste trabalho foi avaliar os efeitos de diferentes sistemas de preparo utilizados para o plantio da cultura da mandioca, em algumas propriedades físicas de um Latossolo Vermelho distrófico. Os tratamentos utilizados foram: plantio sem revolvimento do solo (PSR, preparo mínimo com escarificação (PM e preparo convencional com aração e gradagem (PC. Nas camadas de 0-0,15 e 0,15-0,30 m, foram avaliadas as seguintes propriedades físicas: a densidade do solo (Ds, a curva de retenção de água no solo, a curva de resistência do solo à penetração e o intervalo hídrico ótimo (IHO. Nos sistemas de preparo com reduzida mobilização do solo (PSR e PM, foram constatados maiores valores de Ds e de resistência do solo à penetração. A curva de retenção de água foi influenciada apenas pela Ds, a qual incorporou os efeitos dos sistemas de preparo, independentemente da camada amostrada. A modelagem da curva de resistência do solo à penetração foi influenciada pelos sistemas de preparo e camadas amostradas, com maior resistência à penetração em PSR > PM > PC, acentuada na camada subsuperficial. Com o aumento da Ds, verificou-se redução do IHO associada aos efeitos da resistência do solo à penetração e da porosidade de aeração que determinaram, respectivamente, os limites inferior e superior de água disponível. Os valores do IHO seguiram a seqüência PC = PM > PSR na camada de 0-0,15 m, não diferindo significativamente na camada de 0,15-0,30 m. O valor de densidade do solo crítica (Dsc, densidade em que IHO = 0, foi menor no PSR e PM, comparado ao PC, o que contribuiu para a menor freqüência de valores de densidade maiores que a Dsc no PC.Soil tillage systems and the crop

  3. Design of a management information system for the Shielding Experimental Reactor ageing management

    International Nuclear Information System (INIS)

    He Jie; Xu Xianhong

    2010-01-01

    The problem of nuclear reactor ageing is a topic of increasing importance in nuclear safety recent years. Ageing management is usually implemented for reactors maintenance. In the practice, a large number of data and records need to be processed. However, there are few professional software applications that aid reactor ageing management, especially for research reactors. This paper introduces the design of a new web-based management information system (MIS), named the Shielding Experimental Reactor Ageing Management Information System (SERAMIS). It is an auxiliary means that helps to collect data, keep records, and retrieve information for a research reactor ageing management. The Java2 Enterprise Edition (J2EE) and network database techniques, such as three-tiered model, Model-View-Controller architecture, transaction-oriented operations, and JavaScript techniques, are used in the development of this system. The functionalities of the application cover periodic safety review (PSR), regulatory references, data inspection, and SSCs classification according to ageing management methodology. Data and examples are presented to demonstrate the functionalities. For future work, techniques of data mining will be employed to support decision-making.

  4. Design of a management information system for the Shielding Experimental Reactor ageing management

    Energy Technology Data Exchange (ETDEWEB)

    He Jie, E-mail: hejiejoe@163.co [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Xu Xianhong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2010-01-15

    The problem of nuclear reactor ageing is a topic of increasing importance in nuclear safety recent years. Ageing management is usually implemented for reactors maintenance. In the practice, a large number of data and records need to be processed. However, there are few professional software applications that aid reactor ageing management, especially for research reactors. This paper introduces the design of a new web-based management information system (MIS), named the Shielding Experimental Reactor Ageing Management Information System (SERAMIS). It is an auxiliary means that helps to collect data, keep records, and retrieve information for a research reactor ageing management. The Java2 Enterprise Edition (J2EE) and network database techniques, such as three-tiered model, Model-View-Controller architecture, transaction-oriented operations, and JavaScript techniques, are used in the development of this system. The functionalities of the application cover periodic safety review (PSR), regulatory references, data inspection, and SSCs classification according to ageing management methodology. Data and examples are presented to demonstrate the functionalities. For future work, techniques of data mining will be employed to support decision-making.

  5. UNDERSTANDING THE EVOLUTION OF CLOSE BINARY SYSTEMS WITH RADIO PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuto, O. G. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina); De Vito, M. A. [Instituto de Astrofísica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque S/N (B1900FWA), La Plata (Argentina); Horvath, J. E., E-mail: obenvenu@fcaglp.unlp.edu.ar, E-mail: adevito@fcaglp.unlp.edu.ar, E-mail: foton@astro.iag.usp.br [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo R. do Matão 1226 (05508-090), Cidade Universitária, São Paulo SP (Brazil)

    2014-05-01

    We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a radio pulsar) and a normal donor star, which evolve either to a helium white dwarf (HeWD) or to ultra-short orbital period systems. We consider X-ray irradiation feedback and evaporation due to radio pulsar irradiation. We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in between episodes as binary radio pulsars under conditions in which standard, non-irradiated models predict the occurrence of a low-mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods. Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such quasi-Roche lobe overflow states, rather than hosting a carbon-oxygen WD. We found that CBSs with initial orbital periods of P{sub i} < 1 day evolve into redbacks. Some of them produce low-mass HeWDs, and a subgroup with shorter P{sub i} becomes black widows (BWs). Thus, BWs descend from redbacks, although not all redbacks evolve into BWs. There is mounting observational evidence favoring BW pulsars to be very massive (≳ 2 M {sub ☉}). As they should be redback descendants, redback pulsars should also be very massive, since most of the mass is transferred before this stage.

  6. Converting existing Internal Combustion Generator (ICG) systems into HESs in standalone applications

    International Nuclear Information System (INIS)

    Perera, A.T.D.; Attalage, R.A.; Perera, K.K.C.K.; Dassanayake, V.P.C.

    2013-01-01

    Graphical abstract: - Highlights: • Obtained Pareto fronts of LEC, power supply reliability (PSR) and ICC/GHG emission. • Pareto surface was observed for smaller ICGs when considering LEC–PSR–GHG. • Shape of the LEC–PSR–ICC Pareto front gradually changes with ICG capacity. • Importance of multi-criterion decision-making after multi objective optimization. - Abstract: Expanding existing Internal Combustion Generator (ICG) systems by combining renewable energy sources is getting popular due to global concern on emission of green house gases (GHG) and increasing fossil fuel costs. Life cycle cost, initial capital cost (ICC), power supply reliability of the system, and GHG emission by ICG are factors to be considered in this process. Pareto front of Levelized Energy Cost (LEC)–Unmet Load Fraction (ULF)–GHG emission was taken in this study for four different expansion scenarios. Furthermore, Pareto front of ICC–LE–ULF was taken for three different expansion scenarios in order to analyze the impact of renewable energy integration. The results clearly depict that characteristics of the Pareto front varies with the scale of expansion and objectives taken for the optimization. A detailed analysis was conducted for a scale up problem with a 4 kVA ICG by using the Pareto fronts obtained

  7. GW170817: a neutron star merger in a mass-transferring triple system

    Science.gov (United States)

    Chang, Philip; Murray, Norman

    2018-02-01

    The light curve of GW170817 is surprisingly blue and bright. Assuming that the event is a binary neutron star merger, we argue that blueness and brightness of the light curve is the result of ejecta that contains an substantial amount of thermal energy. To achieve this, the ejecta must be reheated at a substantial distance (1-2000 solar radii) from the merger to avoid losing the energy to adiabatic cooling. We show that this reheating can occur if the merger occurs in a hierarchical triple system where the outer star has evolved and filled its Roche lobe. The outer star feeds mass to the inner binary, forming a circumbinary disc, driving the inner binary to merge. Because the outer star fills its Roche lobe, a substantial fraction of the dynamical ejecta collides with the evolved star, reheating the ejecta in the process. We suggest that the process of mass transfer in hierarchical triples tends to form coplanar triple systems such as PSR J0337+1715, and may provide electromagnetic counterparts to binary black hole mergers.

  8. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    The 1982 model for the formation of Hulse–Taylor binary radio pulsar PSR B1913+16 is described, which since has become the 'standard model' for the formation of the double neutron stars, confirmed by the 2003 discovery of the double pulsar system PSR J0737-3039AB. A brief overview is given of the present status of ...

  9. ITS, TIGER System of Coupled Electron Photon Transport by Monte-Carlo

    International Nuclear Information System (INIS)

    Halbleib, J.A.; Mehlhorn, T.A.; Young, M.F.

    1996-01-01

    1 - Description of program or function: ITS permits a state-of-the-art Monte Carlo solution of linear time-integrated coupled electron/ photon radiation transport problems with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. 2 - Method of solution: Through a machine-portable utility that emulates the basic features of the CDC UPDATE processor, the user selects one of eight codes for running on a machine of one of four (at least) major vendors. With the ITS-3.0 release the PSR-0245/UPEML package is included to perform these functions. The ease with which this utility is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is maximized by employing the best available cross sections and sampling distributions, and the most complete physical model for describing the production and transport of the electron/ photon cascade from 1.0 GeV down to 1.0 keV. Flexibility of construction permits the codes to be tailored to specific applications and the capabilities of the codes to be extended to more complex applications through update procedures. 3 - Restrictions on the complexity of the problem: - Restrictions and/or limitations for ITS depend upon the local operating system

  10. A GIS-based decision support system for regional eco-security assessment and its application on the Tibetan Plateau.

    Science.gov (United States)

    Xiaodan, Wang; Xianghao, Zhong; Pan, Gao

    2010-10-01

    Regional eco-security assessment is an intricate, challenging task. In previous studies, the integration of eco-environmental models and geographical information systems (GIS) usually takes two approaches: loose coupling and tight coupling. However, the present study used a full coupling approach to develop a GIS-based regional eco-security assessment decision support system (ESDSS). This was achieved by merging the pressure-state-response (PSR) model and the analytic hierarchy process (AHP) into ArcGIS 9 as a dynamic link library (DLL) using ArcObjects in ArcGIS and Visual Basic for Applications. Such an approach makes it easy to capitalize on the GIS visualization and spatial analysis functions, thereby significantly supporting the dynamic estimation of regional eco-security. A case study is presented for the Tibetan Plateau, known as the world's "third pole" after the Arctic and Antarctic. Results verified the usefulness and feasibility of the developed method. As a useful tool, the ESDSS can also help local managers to make scientifically-based and effective decisions about Tibetan eco-environmental protection and land use. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  11. Heavy ion collisions with A = 1057: Aspects of nuclear stability and the nuclear equation of state in coalescing neutron-star binary systems

    International Nuclear Information System (INIS)

    Mathews, G.J.; Wilson, J.R.; Evans, C.R.; Detweiler, S.L.

    1987-12-01

    The dynamics of the final stages of the coalescence of two neturon stars (such as the binary pulsar PSR 1913+16) is an unsolved problem in astrophysics. Such systems are probably efficient generators of gravitational radiation, and may be significant contributors to heavy-element nucleosynthesis. The input physics for the study of such systems is similar to that required for the strudy of heavy-ion collision hydrodynamics; e.g., a finite temperature nuclear equation of state, properties of nuclei away from stability, etc. We discuss the development of a relativistic hydrodynamics code in three spatial dimensions for the purpose of studying such neutron-star systems. The properties of the mass-radius relation (determined by the nuclear equation of state) may lead to a proposed mechanism by which hot, highly neutronized matter is ejected from the coalescing stars. This material is photodisintegrated into a free (mostly) neutron gas which may subsequently experience rapid-neutron capture (r-process) nucleosynthesis. 15 refs., 4 figs

  12. SEARCH FOR VERY HIGH ENERGY GAMMA-RAY EMISSION FROM PULSAR-PULSAR WIND NEBULA SYSTEMS WITH THE MAGIC TELESCOPE

    International Nuclear Information System (INIS)

    Anderhub, H.; Biland, A.; Antonelli, L. A.; Antoranz, P.; Balestra, S.; Barrio, J. A.; Bose, D.; Backes, M.; Becker, J. K.; Baixeras, C.; Bastieri, D.; Bock, R. K.; Gonzalez, J. Becerra; Bednarek, W.; Berger, K.; Bernardini, E.; Bonnoli, G.; Bordas, P.; Bosch-Ramon, V.; Tridon, D. Borla

    2010-01-01

    The MAGIC collaboration has searched for high-energy gamma-ray emission of some of the most promising pulsar candidates above an energy threshold of 50 GeV, an energy not reachable up to now by other ground-based instruments. Neither pulsed nor steady gamma-ray emission has been observed at energies of 100 GeV from the classical radio pulsars PSR J0205+6449 and PSR J2229+6114 (and their nebulae 3C58 and Boomerang, respectively) and the millisecond pulsar PSR J0218+4232. Here, we present the flux upper limits for these sources and discuss their implications in the context of current model predictions.

  13. THE QUASI-ROCHE LOBE OVERFLOW STATE IN THE EVOLUTION OF CLOSE BINARY SYSTEMS CONTAINING A RADIO PULSAR

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuto, O. G.; De Vito, M. A. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata and Instituto de Astrofísica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque S/N (B1900FWA), La Plata (Argentina); Horvath, J. E., E-mail: adevito@fcaglp.unlp.edu.ar, E-mail: foton@iag.usp.br [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo R. do Matão 1226 (05508-090), Cidade Universitária, São Paulo SP (Brazil)

    2015-01-01

    We study the evolution of close binary systems formed by a normal (solar composition), intermediate-mass-donor star together with a neutron star. We consider models including irradiation feedback and evaporation. These nonstandard ingredients deeply modify the mass-transfer stages of these binaries. While models that neglect irradiation feedback undergo continuous, long-standing mass-transfer episodes, models including these effects suffer a number of cycles of mass transfer and detachment. During mass transfer, the systems should reveal themselves as low-mass X-ray binaries (LMXBs), whereas when they are detached they behave as binary radio pulsars. We show that at these stages irradiated models are in a Roche lobe overflow (RLOF) state or in a quasi-RLOF state. Quasi-RLOF stars have radii slightly smaller than their Roche lobes. Remarkably, these conditions are attained for an orbital period as well as donor mass values in the range corresponding to a family of binary radio pulsars known as ''redbacks''. Thus, redback companions should be quasi-RLOF stars. We show that the characteristics of the redback system PSR J1723-2837 are accounted for by these models. In each mass-transfer cycle these systems should switch from LMXB to binary radio pulsar states with a timescale of approximately one million years. However, there is recent and fast growing evidence of systems switching on far shorter, human timescales. This should be related to instabilities in the accretion disk surrounding the neutron star and/or radio ejection, still to be included in the model having the quasi-RLOF state as a general condition.

  14. In vivo detection, localization and measurement of radionuclides in man: a detection system for the localization and measurement of small amounts of photon emitters. Final report

    International Nuclear Information System (INIS)

    Laurer, G.R.

    1985-01-01

    A new detector has been devised which, by providing a significant increase in geometric counting efficiency, allows a concurrent reduction in the amount of radioactivity needed to produce an image of the deposition site(s) of radionuclides in humans and/or experimental animals. Consisting of four wedgeshaped NaI(Tl) crystals in a unique geometrical arrangement, the crystals themselves function as the collimator generally employed in radionuclide imaging applications. The four crystals, when coupled, become a 4-crystal unit detector; joined so their active faces form the silhouette of a pyramid. The outside, vertically oriented, rectangular faces of each crystal are placed back-to-back with those of adjoining detectors. Thus, small or large arrays of the 4-crystal unit detectors may be assembled. In practice, the array of detectors will be moved in fixed, discrete steps over the source of radiation to be imaged. As a result of its shape, each count obtained from each crystal at each counting position is different, relative to its position above the source. The array of counts obtained in this manner is the raw spatial information. They are used in a system of linear, simultaneous equations which relate the position of the detectors to the counts obtained at each position. The solution of these equations - utilizing the predetermined point-source-response (PSR) function of the crystals - yields a two-dimensional image of the deposition site of the radioactivity. 18 figs

  15. Deciphering Phosphate Deficiency-Mediated Temporal Effects on Different Root Traits in Rice Grown in a Modified Hydroponic System

    Science.gov (United States)

    Negi, Manisha; Sanagala, Raghavendrarao; Rai, Vandna; Jain, Ajay

    2016-01-01

    Phosphate (Pi), an essential macronutrient for growth and development of plant, is often limiting in soils. Plants have evolved an array of adaptive strategies including modulation of root system architecture (RSA) for optimal acquisition of Pi. In rice, a major staple food, RSA is complex and comprises embryonically developed primary and seminal roots and post-embryonically developed adventitious and lateral roots. Earlier studies have used variant hydroponic systems for documenting the effects of Pi deficiency largely on primary root growth. Here, we report the temporal effects of Pi deficiency in rice genotype MI48 on 15 ontogenetically distinct root traits by using easy-to-assemble and economically viable modified hydroponic system. Effects of Pi deprivation became evident after 4 days- and 7 days-treatments on two and eight different root traits, respectively. The effects of Pi deprivation for 7 days were also evident on different root traits of rice genotype Nagina 22 (N22). There were genotypic differences in the responses of primary root growth along with lateral roots on it and the number and length of seminal and adventitious roots. Notably though, there were attenuating effects of Pi deficiency on the lateral roots on seminal and adventitious roots and total root length in both these genotypes. The study thus revealed both differential and comparable effects of Pi deficiency on different root traits in these genotypes. Pi deficiency also triggered reduction in Pi content and induction of several Pi starvation-responsive (PSR) genes in roots of MI48. Together, the analyses validated the fidelity of this modified hydroponic system for documenting Pi deficiency-mediated effects not only on different traits of RSA but also on physiological and molecular responses. PMID:27200025

  16. Psychiatric rehabilitation education for physicians.

    Science.gov (United States)

    Rudnick, Abraham; Eastwood, Diane

    2013-06-01

    As part of a rapidly spreading reform toward recovery-oriented services, mental health care systems are adopting Psychiatric/Psychosocial Rehabilitation (PSR). Accordingly, PSR education and training programs are now available and accessible. Although psychiatrists and sometimes other physicians (such as family physicians) provide important services to people with serious mental illnesses and may, therefore, need knowledge and skill in PSR, it seems that the medical profession has been slow to participate in PSR education. Based on our experience working in Canada as academic psychiatrists who are also Certified Psychiatric Rehabilitation Practitioners (CPRPs), we offer descriptions of several Canadian initiatives that involve physicians in PSR education. Multiple frameworks guide PSR education for physicians. First, guidance is provided by published PSR principles, such as the importance of self-determination (www.psrrpscanada.ca). Second, guidance is provided by adult education (andragogy) principles, emphasizing the importance of addressing attitudes in addition to knowledge and skills (Knowles, Holton, & Swanson, 2011). Third, guidance in Canada is provided by Canadian Medical Education Directives for Specialists (CanMEDS) principles, which delineate the multiple roles of physicians beyond that of medical expert (Frank, 2005) and have recently been adopted in Australia (Boyce, Spratt, Davies, & McEvoy, 2011). (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  17. Discovery of a young, 267 millisecond pulsar in the supernova remnant W44

    Science.gov (United States)

    Wolszczan, A.; Cordes, J. M.; Dewey, R. J.

    1991-01-01

    This paper reports the discovery of a 267 msec pulsar, PSR 1853 + 01, in the SNR W44 (G34.7 - 0.4), located south of the W44, well within its radio shell and at the outher edge of the X-ray emission region which fills the SNR interior. The PSR 1853 + 01 is separated only 20 arcmin from the PSR 1854 + 00 pulsar discovered by Mohanty (1983). Results of timing observatons of PSR 1853 + 01 are presented, and a possible relationship between the two objects is examined. It is suggested that the two pulsars may have a common origin in a binary system disrupted by the explosion that produced W44.

  18. Low-frequency polarimetry of the millisecond pulsar PSR1937+214

    Energy Technology Data Exchange (ETDEWEB)

    Stinebring, D R [National Radio Astronomy Observatory, Charlottesville, VA (USA); Cordes, J M [Cornell Univ., Ithaca, NY (USA). Dept. of Astronomy; Cornell Univ., Ithaca, NY (USA). National Astronomy and Ionospheric Center)

    1983-11-24

    Polarization observations are reported at 431 MHz that have 4 ..mu..s time resolution and are free from the effects of interstellar dispersion. The interpulse polarization decreases towards lower frequencies, opposite in trend to the polarization of the main pulse and of most other pulsars. The position angles at the center of the main pulse and interpulse are approximately equal and the position angle gradients have the same sign, supporting a model in which the main pulse and interpulse are emitted above opposite magnetic poles.

  19. VizieR Online Data Catalog: Gravitational waves search from known PSR with LIGO (Abbott+, 2017)

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Beer, C.; Bejger, M.; Belahcene, I.; Belgin, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnho Ltz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderon Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglia, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. C.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, H.-P.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conti, L.; Cooper, S. J.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Del Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Davis, D.; Daw, E. J.; Day, B.; Day, R.; de, S.; Debra, D.; Debreczeni, G.; Degallaix, J.; de Laurentis, M.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; Derosa, R. T.; Desalvo, R.; Devenson, J.; Devine R. C, .; Dhurandhar, S.; Diaz, M. C.; di Fiore, L.; di Giovanni M.; di Girolamo, T.; di Lieto, A.; di Pace, S.; di Palma, I.; di Virgilio A.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Alvarez, M.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Etienne, Z.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Fernandez Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, A.; Ghosh, A.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jimenez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kefelian, F.; Keitel, D.; Kelley, D. B.; Kennedy, R.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, C.; Kim, J. C.; Kim, W.; Kim, W.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kirchhoff, R.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kramer, C.; Kringel, V.; Krishnan, B.; Krolak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Liu, J.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Luck, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macfoy, S.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Magana-Sandoval, F.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGra, Th C.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, A.; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muniz, E. A. M.; Murray, P. G.; Mytidis, A.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Nery, M.; Neunzert, A.; Newport, J. M.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, R. J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Purrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero E. A.; QuitzoW-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Rhoades, E.; Ricci, F.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romie, J. H.; Rosinska, D.; Rowan, S.; Rudiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheuer, J.; Schmidt, E.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schonbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T. J.; Shahriar, M. S.; Shapiro, B.; Shawhan P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson, S. P.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tapai, M.; Taracchini, A.; Taylor, R.; Theeg, T.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tippens, T.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torrie, C. I.; Toyra, D.; Travasso, F.; Traylor, G.; Trifiro, D.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tse, M.; Tso, R.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasuth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Vicere, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yu, H.; Yvert, M.; Zadrozny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zucker, M. E.; Zweizig, J.; Buchner, S.; Cognard, I.; Corongiu, A.; Freire, P. C. C.; Guillemot, L.; Hobbs, G. B.; Kerr, M.; Lyne, A. G.; Possenti, A.; Ridolfi, A.; Shannon, R. M.; Stappers, B. W.; Weltevrede, P.; (The Ligo Scientific Collaboration)

    2017-11-01

    We have obtained timings for 200 known pulsars. Timing was performed using the 42ft telescope and Lovell telescope at Jodrell Bank (UK), the 26m telescope at Hartebeesthoek (South Africa), the Parkes radio telescope (Australia), the Nancay Decimetric Radio Telescope (France), the Arecibo Observatory (Puerto Rico) and the Fermi Large Area Telescope (LAT). Of these, 122 have been targeted in previous campaigns (Aasi+ 2014, J/ApJ/785/119), while 78 are new to this search. (1 data file).

  20. The Evaluation of Land Ecological Safety of Chengchao Iron Mine Based on PSR and MEM

    Science.gov (United States)

    Jin, Xiangdong; Chen, Yong

    2018-01-01

    Land ecological security is of vital importance to local security and sustainable development of mining activities. The study has analyzed the potential causal chains between the land ecological security of Iron Mine mining environment, mine resource and the social-economic background. On the base of Pressure-State-Response model, the paper set up a matter element evaluation model of land ecological security, and applies it in Chengchao iron mine. The evaluation result proves to be effective in land ecological evaluation.

  1. An Accurate FFPA-PSR Estimator Algorithm and Tool for Software Effort Estimation

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Murugesan

    2015-01-01

    Full Text Available Software companies are now keen to provide secure software with respect to accuracy and reliability of their products especially related to the software effort estimation. Therefore, there is a need to develop a hybrid tool which provides all the necessary features. This paper attempts to propose a hybrid estimator algorithm and model which incorporates quality metrics, reliability factor, and the security factor with a fuzzy-based function point analysis. Initially, this method utilizes a fuzzy-based estimate to control the uncertainty in the software size with the help of a triangular fuzzy set at the early development stage. Secondly, the function point analysis is extended by the security and reliability factors in the calculation. Finally, the performance metrics are added with the effort estimation for accuracy. The experimentation is done with different project data sets on the hybrid tool, and the results are compared with the existing models. It shows that the proposed method not only improves the accuracy but also increases the reliability, as well as the security, of the product.

  2. Review of PSR framework and development of a DPSIR model to assess greenhouse effect in Taiwan.

    Science.gov (United States)

    Huang, Hui-Fen; Kuo, Jeff; Lo, Shang-Lien

    2011-06-01

    In dealing with the complex issues of greenhouse gas (GHG) emission and climate change mitigation, many interrelated factors such as cost, level of technology development, supply and demand of energy, structure of industry, and expenditures on research and development exist. Using indicators to monitor environmental impacts and evaluate the efficacies of policies and regulations has been practiced for a long time, and it can serve as a useful tool for decision making and for comparison between different countries. Although numerous indicators have been developed for relevant subjects, integrated approaches that consider individual changes, dynamic interaction, and multi-dimensions of indicators are scarce. This paper aimed to develop a Driving Force-Pressure-State-Impact-Response (DPSIR) framework to assess the problems. This DPSIR model is mainly related to energy consumption, environmental impacts, and policy responses. The objectives of the paper were: (1) conduct a literature review on the indicators that have been used in GHG-related studies; (2) develop a DPSIR model that incorporates GHG-related indicators and evaluate their relationships using a cause-effect chain of GHG emission; and (3) develop a calculative method that can be used to explain the dynamic correlation among the interdependent indicators. Taiwan is a significant source of global GHG emissions. A case study, using the developed framework and Taiwan's actual data of the past two decades, was conducted. The results indicate that regulatory strategies for pollution control are inadequate in terms of ensuring environmental quality, and the nature does not have the capability to revert the impacts from the existing level of pollution.

  3. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Sandro Mereghetti

    2017-09-12

    Sep 12, 2017 ... discovery of X-ray variability anti-correlated with the pulsar radio intensity ... a single power law, thus ruling out the interpretation of. Hermsen et al. ..... and a detailed knowledge of its complex phenomenol- ogy. Thanks to the ...

  4. PSR J2124-3358: A Bow Shock Nebula with an X-ray Tail

    Science.gov (United States)

    Chatterjee, S.; Gaensler, B. M.; Vigelius, M.; Cordes, J. M.; Arzoumanian, Z.; Stappers, B.; Ghavamian, P.; Melatos, A.

    2005-12-01

    As neutron stars move supersonically through the interstellar medium, their relativistic winds are confined by the ram pressure of the interstellar medium. The outer shocked layers may emit in Hα , producing a visible bow shock nebula, while the confined relativistic wind may produce radio or X-ray emission. The Hα bow shock nebula powered by the recycled pulsar J2124-3358 is asymmetric about the velocity vector and shows a marked kink. In recent observations with the Chandra X-ray Observatory, we have detected a long, curved X-ray tail associated with the pulsar. The tail is not aligned with the pulsar velocity, but is confined within the optical bow shock. The X-ray spectrum of the tail is well-fit by a power law, consistent with synchrotron emission from the wind termination shock and the post-shock flow. The presence of Hα and X-ray emission allows us to trace both the external ambient medium and the confined wind. In magnetohydrodynamic simulations, we verify that a bulk flow and non-uniformities in the ambient medium can produce the observed shape of the nebula, possibly in combination with an anisotropic pulsar wind. Support for this work was provided by the National Aeronautics and Space Administration through Chandra Award Number GO5-6075X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060.

  5. Discovery of a remarkable subpulse drift pattern in PSR B0818-41

    Science.gov (United States)

    Bhattacharyya, B.; Gupta, Y.; Gil, J.; Sendyk, M.

    2007-05-01

    We report the discovery of a remarkable subpulse drift pattern in the relatively less-studied wide profile pulsar B0818-41 using high-sensitivity Giant Metrewave Radio Telescope (GMRT) observations. We find simultaneous occurrences of three drift regions with two different drift rates: an inner region with steeper apparent drift rate flanked on each side by a region of slower apparent drift rate. Furthermore, these closely spaced drift bands always maintain a constant phase relationship. Though these drift regions have significantly different values for the measured P2, the measured P3 value is the same and equal to 18.3P1. We interpret the unique drift pattern of this pulsar as being created by the intersection of our line of sight (LOS) with two conal rings on the polar cap of a fairly aligned rotator (inclination angle α ~ 11°), with an `inner' LOS geometry (impact angle ). We argue that both rings have the same values for the carousel rotation periodicity P4 and the number of sparks Nsp. We find that Nsp is 19-21 and show that it is very likely that P4 is the same as the measured P3, making it a truly unique pulsar. We present results from simulations of the radiation pattern using the inferred parameters, which support our interpretations and reproduce the average profile as well as the observed features in the drift pattern quite well.

  6. Pulsar spin-down: the glitch-dominated rotation of PSR J0537-6910

    Science.gov (United States)

    Antonopoulou, D.; Espinoza, C. M.; Kuiper, L.; Andersson, N.

    2018-01-01

    The young, fast-spinning X-ray pulsar J0537-6910 displays an extreme glitch activity, with large spin-ups interrupting its decelerating rotation every ∼100 d. We present nearly 13 yr of timing data from this pulsar, obtained with the Rossi X-ray Timing Explorer. We discovered 22 new glitches and performed a consistent analysis of all 45 glitches detected in the complete data span. Our results corroborate the previously reported strong correlation between glitch spin-up size and the time to the next glitch, a relation that has not been observed so far in any other pulsar. The spin evolution is dominated by the glitches, which occur at a rate of ∼3.5 per year, and the post-glitch recoveries, which prevail the entire interglitch intervals. This distinctive behaviour provides invaluable insights into the physics of glitches. The observations can be explained with a multicomponent model that accounts for the dynamics of the neutron superfluid present in the crust and core of neutron stars. We place limits on the moment of inertia of the component responsible for the spin-up and, ignoring differential rotation, the velocity difference it can sustain with the crust. Contrary to its rapid decrease between glitches, the spin-down rate increased over the 13 yr, and we find the long-term braking index nl = -1.22(4), the only negative braking index seen in a young pulsar. We briefly discuss the plausible interpretations of this result, which is in stark contrast to the predictions of standard models of pulsar spin-down.

  7. A glitch in the Crab pulsar (PSR B0531+21)

    Science.gov (United States)

    Shaw, Benjamin; Lyne, Andrew; Bassa, Cees; Breton, Rene; Jordan, Christine; Keith, Michael; Mickaliger, Mitchell B.; Stappers, Benjamin; Weltevrede, Patrick

    2018-05-01

    We have detected a glitch in the Crab pulsar, B0531+21, on 2018-04-29. The Crab pulsar is regularly monitored with the 42-ft and Lovell telescopes at the Jodrell Bank Observatory as part of the pulsar timing programme.

  8. Transcriptome profiling of Nasonia vitripennis testis reveals novel transcripts expressed from the selfish B chromosome, paternal sex ratio.

    Science.gov (United States)

    Akbari, Omar S; Antoshechkin, Igor; Hay, Bruce A; Ferree, Patrick M

    2013-09-04

    A widespread phenomenon in nature is sex ratio distortion of arthropod populations caused by microbial and genetic parasites. Currently little is known about how these agents alter host developmental processes to favor one sex or the other. The paternal sex ratio (PSR) chromosome is a nonessential, paternally transmitted centric fragment that segregates in natural populations of the jewel wasp, Nasonia vitripennis. To persist, PSR is thought to modify the hereditary material of the developing sperm, with the result that all nuclear DNA other than the PSR chromosome is destroyed shortly after fertilization. This results in the conversion of a fertilized embryo--normally a female--into a male, thereby insuring transmission of the "selfish" PSR chromosome, and simultaneously leading to wasp populations that are male-biased. To begin to understand this system at the mechanistic level, we carried out transcriptional profiling of testis from WT and PSR-carrying males. We identified a number of transcripts that are differentially expressed between these conditions. We also discovered nine transcripts that are uniquely expressed from the PSR chromosome. Four of these PSR-specific transcripts encode putative proteins, whereas the others have very short open reading frames and no homology to known proteins, suggesting that they are long noncoding RNAs. We propose several different models for how these transcripts could facilitate PSR-dependent effects. Our analyses also revealed 15.71 MB of novel transcribed regions in the N. vitripennis genome, thus increasing the current annotation of total transcribed regions by 53.4%. Finally, we detected expression of multiple meiosis-related genes in the wasp testis, despite the lack of conventional meiosis in the male sex.

  9. System Budgets

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1996-01-01

    The lecture note is aimed at introducing system budgets for optical communication systems. It treats optical fiber communication systems (six generations), system design, bandwidth effects, other system impairments and optical amplifiers.......The lecture note is aimed at introducing system budgets for optical communication systems. It treats optical fiber communication systems (six generations), system design, bandwidth effects, other system impairments and optical amplifiers....

  10. Protein synthesis rate measured with l-[1-11C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

    International Nuclear Information System (INIS)

    Plaat, B.; Mastik, M.; Molenaar, W.; Kole, A.; Vaalburg, W.; Hoekstra, H.

    1999-01-01

    Protein synthesis rate (PSR) can be assessed in vivo using positron emission tomography with l-[1- 11 C]tyrosine (TYR-PET). Biological activity of soft tissue sarcomas (STS) can be measured in vitro by the mitotic rate and number of proliferating cells. In STS the grade of malignancy, in which the mitotic index plays a major role, is considered to be the major standard in predicting biological tumour behaviour. This study was designed to test the validity of TYR-PET in relation to different histopathological features. In 21 patients with untreated STS, the PSR was measured using TYR-PET. The number of mitoses was counted and tumours were graded according to the grading system of Coindre et al. (Cancer 1986; 58:306-309). Proliferative activity was assessed by immunohistological detection of the Ki-67 nuclear antigen using MIB-1 monoclonal antibody. To test the association between the PSR and these tumour parameters, a correlation analysis was performed. A significant (P<0.05) correlation was found between PSR and the Ki-67 proliferation index (R = 0.54), and between PSR and mitotic rate (R = 0.64). There was no correlation between PSR and tumour grade. The present study in malignant soft tissue tumours relates in vivo tumour metabolism as established with TYR-PET to tumour activity measured in vitro and indicates that the non-invasive method of TYR-PET can estimate the mitotic and proliferative activity in STS. (orig.)

  11. On The Origin Of Hyper-Fast Pulsars

    Science.gov (United States)

    Gvaramadze, V. V.

    2006-08-01

    Recent proper motion and parallax measurements for the pulsar PSR B1508+55 gave the highest (transverse) velocity (~1100 km/s) ever measured for a neutron star (Chatterjee et al. 2005). The spin-down characteristics of PSR B1508+55 (typical of non-recycled pulsars) imply that the high velocity of this pulsar cannot be solely due to disruption of a tight massive binary system. A possible way to account for the high velocity of PSR B1508+55 is to assume that at least a part of this velocity is due to a natal or post-natal kick (Chatterjee et al. 2005). We propose an alternative explanation for the origin of hyper-fast pulsars. We suggest that PSR B1508+55 could be the remnant of a (symmetric) supernova explosion of the helium core of a massive star expelled at high velocity from the dense core of a young massive stellar cluster by an intermediate-mass (binary) black hole. The maximum peculiar velocity of the helium core is limited by the parabolic velocity on its surface and could be as large as ~2000 km/s. Thus, one can account not only for the high velocity measured for PSR B1508+55, but also for the even higher velocity of ~1600 km/s inferred for the pulsar PSR B2224+65 (Guitar; Chatterjee & Cordes 2004) on the basis of its proper motion and the dispersion measure distance estimate.

  12. Algorithms for searching Fast radio bursts and pulsars in tight binary systems.

    Science.gov (United States)

    Zackay, Barak

    2017-01-01

    Fast radio bursts (FRB's) are an exciting, recently discovered, astrophysical transients which their origins are unknown.Currently, these bursts are believed to be coming from cosmological distances, allowing us to probe the electron content on cosmological length scales. Even though their precise localization is crucial for the determination of their origin, radio interferometers were not extensively employed in searching for them due to computational limitations.I will briefly present the Fast Dispersion Measure Transform (FDMT) algorithm,that allows to reduce the operation count in blind incoherent dedispersion by 2-3 orders of magnitude.In addition, FDMT enables to probe the unexplored domain of sub-microsecond astrophysical pulses.Pulsars in tight binary systems are among the most important astrophysical objects as they provide us our best tests of general relativity in the strong field regime.I will provide a preview to a novel algorithm that enables the detection of pulsars in short binary systems using observation times longer than an orbital period.Current pulsar search programs limit their searches for integration times shorter than a few percents of the orbital period.Until now, searching for pulsars in binary systems using observation times longer than an orbital period was considered impossible as one has to blindly enumerate all options for the Keplerian parameters, the pulsar rotation period, and the unknown DM.Using the current state of the art pulsar search techniques and all computers on the earth, such an enumeration would take longer than a Hubble time. I will demonstrate that using the new algorithm, it is possible to conduct such an enumeration on a laptop using real data of the double pulsar PSR J0737-3039.Among the other applications of this algorithm are:1) Searching for all pulsars on all sky positions in gamma ray observations of the Fermi LAT satellite.2) Blind searching for continuous gravitational wave sources emitted by pulsars with

  13. Ventilation systems

    International Nuclear Information System (INIS)

    Gossler

    1980-01-01

    The present paper deals with - controlled area ventilation systems - ventilation systems for switchgear-building and control-room - other ventilation systems for safety equipments - service systems for ventilation systems. (orig./RW)

  14. Observations and modeling of the companions of short period binary millisecond pulsars: evidence for high-mass neutron stars

    International Nuclear Information System (INIS)

    Schroeder, Joshua; Halpern, Jules

    2014-01-01

    We present observations of fields containing eight recently discovered binary millisecond pulsars using the telescopes at MDM Observatory. Optical counterparts to four of these systems are detected, one of which, PSR J2214+3000, is a novel detection. Additionally, we present the fully phase-resolved B, V, and R light curves of the optical counterparts to two objects, PSR J1810+1744 and PSR J2215+5135 for which we employ model fitting using the eclipsing light curve (ELC) model of Orosz and Hauschildt to measure the unknown system parameters. For PSR J1810+1744, we find that the system parameters cannot be fit even assuming that 100% of the spin-down luminosity of the pulsar is irradiating the secondary, and so radial velocity measurements of this object will be required for the complete solution. However, PSR J2215+5135 exhibits light curves that are extremely well constrained using the ELC model and we find that the mass of the neutron star is constrained by these and the radio observations to be M NS > 1.75 M ☉ at the 3σ level. We also find a discrepancy between the model temperature and the measured colors of this object, which we interpret as possible evidence for an additional high-temperature source such as a quiescent disk. Given this and the fact that PSR J2215+5135 contains a relatively high mass companion (M c > 0.1 M ☉ ), we propose that similar to the binary pulsar systems PSR J1023+0038 and IGR J18245–2452, the pulsar may transition between accretion- and rotation-powered modes.

  15. Embedded Systems

    Indian Academy of Sciences (India)

    Embedded system, micro-con- troller ... Embedded systems differ from general purpose computers in many ... Low cost: As embedded systems are extensively used in con- .... operating systems for the desktop computers where scheduling.

  16. Thermal systems; Systemes thermiques

    Energy Technology Data Exchange (ETDEWEB)

    Lalot, S. [Valenciennes Univ. et du Hainaut Cambresis, LME, 59 (France); Lecoeuche, S. [Ecole des Mines de Douai, Dept. GIP, 59 - Douai (France)]|[Lille Univ. des Sciences et Technologies, 59 - Villeneuve d' Ascq (France); Ahmad, M.; Sallee, H.; Quenard, D. [CSTB, 38 - Saint Martin d' Heres (France); Bontemps, A. [Universite Joseph Fourier, LEGI/GRETh, 38 - Grenoble (France); Gascoin, N.; Gillard, P.; Bernard, S. [Laboratoire d' Energetique, Explosion, Structure, 18 - Bourges (France); Gascoin, N.; Toure, Y. [Laboratoire Vision et Robotique, 18 - Bourges (France); Daniau, E.; Bouchez, M. [MBDA, 18 - Bourges (France); Dobrovicescu, A.; Stanciu, D. [Bucarest Univ. Polytechnique, Faculte de Genie Mecanique (Romania); Stoian, M. [Reims Univ. Champagne Ardenne, Faculte des Sciences, UTAP/LTM, 51 (France); Bruch, A.; Fourmigue, J.F.; Colasson, S. [CEA Grenoble, Lab. Greth, 38 (France); Bontemps, A. [Universite Joseph Fourier, LEGI/GRETh, 38 - Grenoble (France); Voicu, I.; Mare, T.; Miriel, J. [Institut National des Sciences Appliquees (INSA), LGCGM, IUT, 35 - Rennes (France); Galanis, N. [Sherbrooke Univ., Genie Mecanique, QC (Canada); Nemer, M.; Clodic, D. [Ecole des Mines de Paris, Centre Energetique et Procedes, 75 (France); Lasbet, Y.; Auvity, B.; Castelain, C.; Peerhossaini, H. [Nantes Univ., Ecole Polytechnique, Lab. de Thermocinetiquede Nantes, UMR-CNRS 6607, 44 (France)

    2005-07-01

    This session about thermal systems gathers 26 articles dealing with: neural model of a compact heat exchanger; experimental study and numerical simulation of the thermal behaviour of test-cells with walls made of a combination of phase change materials and super-insulating materials; hydraulic and thermal modeling of a supercritical fluid with pyrolysis inside a heated channel: pre-dimensioning of an experimental study; energy analysis of the heat recovery devices of a cryogenic system; numerical simulation of the thermo-hydraulic behaviour of a supercritical CO{sub 2} flow inside a vertical tube; mixed convection inside dual-tube exchangers; development of a nodal approach with homogenization for the simulation of the brazing cycle of a heat exchanger; chaotic exchanger for the cooling of low temperature fuel cells; structural optimization of the internal fins of a cylindrical generator; a new experimental approach for the study of the local boiling inside the channels of exchangers with plates and fins; experimental study of the flow regimes of boiling hydrocarbons on a bundle of staggered tubes; energy study of heat recovery exchangers used in Claude-type refrigerating systems; general model of Carnot engine submitted to various operating constraints; the free pistons Stirling cogeneration system; natural gas supplied cogeneration system with polymer membrane fuel cell; influence of the CRN coating on the heat flux inside the tool during the wood unrolling process; transport and mixture of a passive scalar injected inside the wake of a Ahmed body; control of a laser welding-brazing process by infrared thermography; 2D self-adaptative method for contours detection: application to the images of an aniso-thermal jet; exergy and exergy-economical study of an 'Ericsson' engine-based micro-cogeneration system; simplified air-conditioning of telephone switching equipments; parametric study of the 'low-energy' individual dwelling; brief synthesis of

  17. Data Systems vs. Information Systems

    OpenAIRE

    Amatayakul, Margret K.

    1982-01-01

    This paper examines the current status of “hospital information systems” with respect to the distinction between data systems and information systems. It is proposed that the systems currently existing are incomplete data dystems resulting in ineffective information systems.

  18. EXPERT SYSTEMS

    OpenAIRE

    Georgiana Marin; Mihai Catalin Andrei

    2011-01-01

    In recent decades IT and computer systems have evolved rapidly in economic informatics field. The goal is to create user friendly information systems that respond promptly and accurately to requests. Informatics systems evolved into decision assisted systems, and such systems are converted, based on gained experience, in expert systems for creative problem solving that an organization is facing. Expert systems are aimed at rebuilding human reasoning on the expertise obtained from experts, sto...

  19. German (GRS) approach to accident analysis (part I). German licensing basis for accident analyses. Applicants accident analyses in second part license for Konvoi-plants. Appendix 1. Assessor accident analyses in second part license for Konvoi-plants. Appendix 2. Reference list of DBA to be considered in the safety status analysis of a PSR. Appendix 3a. Reference list of special very rare and BDB plant conditions to be considered in the safety status analysis of a PSE. Appendix 3b

    International Nuclear Information System (INIS)

    Velkov, K.

    2002-01-01

    Appendix 1: The Safety Analysis Report (S.A.R.) is presented from 3 Handbooks - ECC Handbook (LOCA), Plant Dynamics Handbook (Transients incl. ATWS), and Core Design Handbook. The first one Conceived as Living handbook, Basis for design, catalogue of transients, specifications and licensing. Handbook contains LOCA in primary system, it contains also core damage analysis, and description of codes, description of essential plant data and code input data. The second one consists of Basis for design, commissioning, operation, and catalogue of transients, specifications and licensing, as well as specified operation, disturbed operation, incidents, non-LOCA, SS-procedures and Code description. The third book consists of Reactivity balance and reactivity coefficients, efficiency of shutdown systems. Calculation of burn up cycle, power density distribution, and critical boron concentration. Also Codes used, as SAV79A standard analysis methodology including FASER for nuclear data generation, MEDIUM and PANBOX for static and transient core calculations. Appendix 2: The three TUEV (Technical Inspection Agencies) responsible for the three individual plants of type KONVOI: TUEV Bayern for ISAR-2, TUV-Hanover for KKE, TUEV-Stuttgart for GKN-2 and GRS performed the safety assessment. TUV-Bayern for disturbance and failure of secondary heat sink without loss of coolant (failure of main heat sink, erroneous operation of valves in MS and in FW system, failure of MFW supply), long term LONOP, performance of selected SBLOCA analyses. TUV Hanover for disturbances due to failure of MCPs, short term LONOP, damages of SG tubes incl. SGTR, performance of selected LOCA analyses (blowdown phase of LBLOCA). TUV-Stuttgart for breaks and leaks in MS and FW system with and without leaks in SG tubes. GRS for ATWS, sub-cooling transients due to disturbances on secondary side, initial and boundary conditions for transients with opening of pressurizer valves with and without stuck-open, most of the

  20. Multibody Systems

    DEFF Research Database (Denmark)

    Wagner, Falko Jens

    1999-01-01

    Multibody Systems is one area, in which methods for solving DAEs are of special interst. This chapter is about multibody systems, why they result in DAE systems and what kind of problems that can arise when dealing with multibody systems and formulating their corresponding DAE system....

  1. System dynamics

    International Nuclear Information System (INIS)

    Kim, Do Hun; Mun, Tae Hun; Kim, Dong Hwan

    1999-02-01

    This book introduces systems thinking and conceptual tool and modeling tool of dynamics system such as tragedy of single thinking, accessible way of system dynamics, feedback structure and causal loop diagram analysis, basic of system dynamics modeling, causal loop diagram and system dynamics modeling, information delay modeling, discovery and application for policy, modeling of crisis of agricultural and stock breeding products, dynamic model and lesson in ecosystem, development and decadence of cites and innovation of education forward system thinking.

  2. A study of adopting maintenance rule under the periodic safety review and reliability centered maintenance program

    International Nuclear Information System (INIS)

    Kilyoo, Kim

    2001-01-01

    U.S Maintenance Rule (MR) has three main functions. One is to monitor the performance changes of SSCs (Structure, System, and Component) caused by risk informed applications. Periodic Safety Review (PSR) program is widely adopted in Europe while it is not adopted in U. S. A where MR and new oversight program are instead used. Recently, in Korea, it was determined to adopt PSR, and the first PSR program has started this year for Kori unit 1 as a pilot plant. Also, a traditional Reliability Centered Maintenance (RCM) has been performed for 4 systems of YGN unit 1 and 2 and it will be applied to the other nuclear power plants in Korea. However, since MR is adopting many useful concept of RCM, traditional RCM could not be further performed without being associated with MR. Thus, MR, RCM and PSR have recently become hot issue policies which should be well associated each other in Korea, and this paper suggests a desirable new maintenance process which would embrace the concepts of the three policies, and also discusses whether U.S. MR is necessary even though a PSR program is already adopted, and if necessary, then how cost-effectively it can be introduced to. (author)

  3. Coupling component systems towards systems of systems

    OpenAIRE

    Autran , Frédéric; Auzelle , Jean-Philippe; Cattan , Denise; Garnier , Jean-Luc; Luzeaux , Dominique; Mayer , Frédérique; Peyrichon , Marc; Ruault , Jean-René

    2008-01-01

    International audience; Systems of systems (SoS) are a hot topic in our "fully connected global world". Our aim is not to provide another definition of what SoS are, but rather to focus on the adequacy of reusing standard system architecting techniques within this approach in order to improve performance, fault detection and safety issues in large-scale coupled systems that definitely qualify as SoS, whatever the definition is. A key issue will be to secure the availability of the services pr...

  4. Systems effectiveness

    CERN Document Server

    Habayeb, A R

    1987-01-01

    Highlights three principal applications of system effectiveness: hardware system evaluation, organizational development and evaluation, and conflict analysis. The text emphasizes the commonality of the system effectiveness discipline. The first part of the work presents a framework for system effectiveness, partitioning and hierarchy of hardware systems. The second part covers the structure, hierarchy, states, functions and activities of organizations. Contains an extended Appendix on mathematical concepts and also several project suggestions.

  5. Auxiliary systems

    International Nuclear Information System (INIS)

    Meyer, P.J.

    1981-01-01

    Systems included under the heading ''Reactor Auxillary Systems'' are those immediately involved with the reactor operation. These include the systems for dosing and letdown of reactor coolant, as well as for the chemical dosing, purification and treatment of the reactor coolant and the cooling system in the controlled area. The ancillary systems are mainly responsible for liquid and gaseous treatment and the waste treatment for final storage. (orig.)

  6. NPP Krsko periodic safety review. Safety assessment and analyses

    International Nuclear Information System (INIS)

    Basic, I.; Spiler, J.; Thaulez, F.

    2002-01-01

    Definition of a PSR (Periodic Safety Review) project is a comprehensive safety review of a plant after ten years of operation. The objective is a verification by means of a comprehensive review using current methods that the plant remains safe when judged against current safety objectives and practices and that adequate arrangements are in place to maintain plant safety. The overall goals of the NEK PSR Program are defined in compliance with the basic role of a PSR and the current practice typical for most of the countries in EU. This practice is described in the related guides and good practice documents issued by international organizations. The overall goals of the NEK PSR are formulated as follows: to demonstrate that the plant is as safe as originally intended; to evaluate the actual plant status with respect to aging and wear-out identifying any structures, systems or components that could limit the life of the plant in the foreseeable future, and to identify appropriate corrective actions, where needed; to compare current level of safety in the light of modern standards and knowledge, and to identify where improvements would be beneficial for minimizing deviations at justifiable costs. The Krsko PSR will address the following safety factors: Operational Experience, Safety Assessment, EQ and Aging Management, Safety Culture, Emergency Planning, Environmental Impact and Radioactive Waste.(author)

  7. Hidden slow pulsars in binaries

    Science.gov (United States)

    Tavani, Marco; Brookshaw, Leigh

    1993-01-01

    The recent discovery of the binary containing the slow pulsar PSR 1718-19 orbiting around a low-mass companion star adds new light on the characteristics of binary pulsars. The properties of the radio eclipses of PSR 1718-19 are the most striking observational characteristics of this system. The surface of the companion star produces a mass outflow which leaves only a small 'window' in orbital phase for the detection of PSR 1718-19 around 400 MHz. At this observing frequency, PSR 1718-19 is clearly observable only for about 1 hr out of the total 6.2 hr orbital period. The aim of this Letter is twofold: (1) to model the hydrodynamical behavior of the eclipsing material from the companion star of PSR 1718-19 and (2) to argue that a population of binary slow pulsars might have escaped detection in pulsar surveys carried out at 400 MHz. The possible existence of a population of partially or totally hidden slow pulsars in binaries will have a strong impact on current theories of binary evolution of neutron stars.

  8. Radiation safety assessment and development of environmental radiation monitoring technology

    CERN Document Server

    Choi, B H; Kim, S G

    2002-01-01

    The Periodic Safety Review(PSR) of the existing nuclear power plants is required every ten years according to the recently revised atomic energy acts. The PSR of Kori unit 1 and Wolsong unit 1 that have been operating more than ten years is ongoing to comply the regulations. This research project started to develop the techniques necessary for the PSR. The project developed the following four techniques at the first stage for the environmental assessment of the existing plants. 1) Establishment of the assessment technology for contamination and accumulation trends of radionuclides, 2) alarm point setting of environmental radiation monitoring system, 3) Development of Radiation Safety Evaluation Factor for Korean NPP, and 4) the evaluation of radiation monitoring system performance and set-up of alarm/warn set point. A dynamic compartment model to derive a relationship between the release rates of gas phase radionuclides and the concentrations in the environmental samples. The model was validated by comparing ...

  9. Bitcoin System

    Directory of Open Access Journals (Sweden)

    Jan Lánský

    2017-06-01

    Full Text Available Cryptocurrency systems are purely digital and decentralized systems that use cryptographic principles to confirm transactions. Bitcoin is the first and also the most widespread cryptocurrency. The aim of this article is to introduce Bitcoin system using a language understandable also to readers without computer science education. This article captures the Bitcoin system from three perspectives: internal structure, network and users. Emphasis is placed on brief and clear definitions (system components and their mutual relationships. A new system view of the stated terms constitutes author’s own contribution.

  10. Supernova remnant S147 and its associated neutron star(s)

    OpenAIRE

    Gvaramadze, V. V.

    2005-01-01

    The supernova remnant S147 harbors the pulsar PSR J0538+2817 whose characteristic age is more than an order of magnitude greater than the kinematic age of the system (inferred from the angular offset of the pulsar from the geometric center of the supernova remnant and the pulsar proper motion). To reconcile this discrepancy we propose that PSR J0538+2817 could be the stellar remnant of the first supernova explosion in a massive binary system and therefore could be as old as its characteristic...

  11. JOSHUA system

    International Nuclear Information System (INIS)

    Honeck, H.C.

    1975-04-01

    A major computational system called JOSHUA has been under development at the Savannah River Laboratory since 1968. The JOSHUA System has two major parts: the Operating System and the Application System. The Operating System has been in production use since 1970 and provides data management, terminal, and job execution facilities. The Application System uses these facilities in solving problems in reactor physics and engineering. Features of the Application System are the two-dimensional lattice physics and three-dimensional transient reactor physics capabilities, which have been in use since 1971 and 1974, respectively. The capabilities of the JOSHUA System are summarized, and statistics on size, use, and development effort are provided. (U.S.)

  12. Systems thinking.

    Science.gov (United States)

    Cabrera, Derek; Colosi, Laura; Lobdell, Claire

    2008-08-01

    Evaluation is one of many fields where "systems thinking" is popular and is said to hold great promise. However, there is disagreement about what constitutes systems thinking. Its meaning is ambiguous, and systems scholars have made diverse and divergent attempts to describe it. Alternative origins include: von Bertalanffy, Aristotle, Lao Tsu or multiple aperiodic "waves." Some scholars describe it as synonymous with systems sciences (i.e., nonlinear dynamics, complexity, chaos). Others view it as taxonomy-a laundry list of systems approaches. Within so much noise, it is often difficult for evaluators to find the systems thinking signal. Recent work in systems thinking describes it as an emergent property of four simple conceptual patterns (rules). For an evaluator to become a "systems thinker", he or she need not spend years learning many methods or nonlinear sciences. Instead, with some practice, one can learn to apply these four simple rules to existing evaluation knowledge with transformative results.

  13. Cognitive Systems

    DEFF Research Database (Denmark)

    The tutorial will discuss the definition of cognitive systems as the possibilities to extend the current systems engineering paradigm in order to perceive, learn, reason and interact robustly in open-ended changing environments. I will also address cognitive systems in a historical perspective...... to be modeled within a limited set of predefined specifications. There will inevitably be a need for robust decisions and behaviors in novel situations that include handling of conflicts and ambiguities based on the capability and knowledge of the artificial cognitive system. Further, there is a need...... in cognitive systems include e.g. personalized information systems, sensor network systems, social dynamics system and Web2.0, and cognitive components analysis. I will use example from our own research and link to other research activities....

  14. Crystal Systems.

    Science.gov (United States)

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  15. Filter systems

    International Nuclear Information System (INIS)

    Vanin, V.R.

    1990-01-01

    The multidetector systems for high resolution gamma spectroscopy are presented. The observable parameters for identifying nuclides produced simultaneously in the reaction are analysed discussing the efficiency of filter systems. (M.C.K.)

  16. Expert systems

    International Nuclear Information System (INIS)

    Haldy, P.A.

    1988-01-01

    The definitions of the terms 'artificial intelligence' and 'expert systems', the methodology, areas of employment and limits of expert systems are discussed. The operation of an expert system is described, especially the presentation and organization of knowledge as well as interference and control. Methods and tools for expert system development are presented and their application in nuclear energy are briefly addressed. 7 figs., 2 tabs., 6 refs

  17. Expert System

    DEFF Research Database (Denmark)

    Hildebrandt, Thomas Troels; Cattani, Gian Luca

    2016-01-01

    An expert system is a computer system for inferring knowledge from a knowledge base, typically by using a set of inference rules. When the concept of expert systems was introduced at Stanford University in the early 1970s, the knowledge base was an unstructured set of facts. Today the knowledge b...... for the application of expert systems, but also raises issues regarding privacy and legal liability....

  18. Retrofitting Systems

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    This report gives an overview of the different retrofitting possibilities that are available today. The report looks at both external and internal systems for external wall constructions, roof constructions, floor constructions and foundations. All systems are described in detail in respect to use...... and methods, and the efficiency of the different systems are discussed....

  19. Multifunction system

    International Nuclear Information System (INIS)

    Wauthier, J.; Fiori, R.

    1990-01-01

    The development, the characteristics and the applications of a multifunction system are presented. The system is used on the RBES laboratory pipes, at Marcoule. The system was developed in order to allow, without time loss, the modification of the circuit function by replacing only one component. The following elements form the multifunction system: a fixed base, which is part of the tube, a removable piece, which is inserted into the base, a cover plate and its locking system. The material, chosen among commercial trade marks, required small modifications in order to be used in the circuit [fr

  20. Operating systems

    CERN Document Server

    Tsichritzis, Dionysios C; Rheinboldt, Werner

    1974-01-01

    Operating Systems deals with the fundamental concepts and principles that govern the behavior of operating systems. Many issues regarding the structure of operating systems, including the problems of managing processes, processors, and memory, are examined. Various aspects of operating systems are also discussed, from input-output and files to security, protection, reliability, design methods, performance evaluation, and implementation methods.Comprised of 10 chapters, this volume begins with an overview of what constitutes an operating system, followed by a discussion on the definition and pr

  1. Periodontal disease detection in primary and mixed dentitions.

    Science.gov (United States)

    Nobre, C M Guimarães; Fernandes-Costa, A N; de Melo Soares, M S; Pugliesi, D M Carvalho; de Vasconcelos Gurgel, B C

    2016-10-01

    This was to compare the periodontal status of children with primary and mixed dentition at the time of their first consultation. Children (200), aged 0-12 years (156 with mixed and 44 with primary dentition), were examined by assessing their simplified plaque index (PI) and simplified periodontal record (PSR). Statistical analysis (Chi-square test) was performed with appropriate software to find any significant associations between sex, type of dentition and PI with the PSR codes (0, 1, 2, 3 and 4). There was no statistically significant difference with regard to gender (p = 0.82). Generalised PI was associated more significantly with mixed dentition (p = 0.025 and higher PSR scores (p periodontal examination in children to diagnose and prevent future periodontal disease and maintain their dentition as well as to identify any associated systemic conditions.

  2. Monitoring Baby - Listening in on the Youngest Known Pulsar

    Science.gov (United States)

    Gotthelf, Eric

    We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type supernova remnant Kes 75. Based on its spin-down rate and X- ray spectrum, PSR J1846-0258 is likely the youngest known rotation- powered pulsar. Compared to the Crab pulsar, however, its period, spin- down rate, and spin-down to X-ray luminosity conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of glitches. This pulsar provides important insight into the evolution of the youngest NS-SNR systems.

  3. Systems integration.

    Science.gov (United States)

    Siemieniuch, C E; Sinclair, M A

    2006-01-01

    The paper presents a view of systems integration, from an ergonomics/human factors perspective, emphasising the process of systems integration as is carried out by humans. The first section discusses some of the fundamental issues in systems integration, such as the significance of systems boundaries, systems lifecycle and systems entropy, issues arising from complexity, the implications of systems immortality, and so on. The next section outlines various generic processes for executing systems integration, to act as guides for practitioners. These address both the design of the system to be integrated and the preparation of the wider system in which the integration will occur. Then the next section outlines some of the human-specific issues that would need to be addressed in such processes; for example, indeterminacy and incompleteness, the prediction of human reliability, workload issues, extended situation awareness, and knowledge lifecycle management. For all of these, suggestions and further readings are proposed. Finally, the conclusions section reiterates in condensed form the major issues arising from the above.

  4. BOLD/VENTURE-4, Reactor Analysis System with Sensitivity and Burnup

    International Nuclear Information System (INIS)

    1998-01-01

    cross section variation or correlation on nuclide concentrations is provided, but a temperature dependence is coded. Steady state condition with continuous fueling is established by a global iterative scheme that applies the criticality search scheme in the neutronics and models fuel movement directly in the exposure code. Time-dependent sensitivity data applies the forward march, reverse importance approach. The codes do not process data from the user input data stream allowing flexible task assignment along selected calculational paths. Multigroup cross section data are produced locally using the PSR-0063/AMPX II or CCC-0450/SCALE-2 code systems to produce resonance shielding (NITAWL) and cell weighted (XSDRN) microscopic cross sections. Locally, each code is compiled and loaded, and only one version is maintained in a quality assurance state in load module form. An on-line catalog procedure, installed with system support, provides job control instructions with nominal default of space allocation to files. Executing the catalog procedure makes the driver memory resident. The first user input data line must be the control module name used for the run. VENTURE-PC: The VENTURE module applies the finite-difference diffusion or a simple P1 approximation. VENTURE uses an outer-inner iteration scheme with several different data handling methods. Over-relaxation is applied to the inner and outer iterations, and succeeding flux iterates may be accelerated with the Chebychev process. - The BURNER code (module EXPOSURE) uses a difference formulation based on average generation rates; or a matrix exponential formulation to approximate the solution of the coupled burnup differential equations; or an explicit solution for simply coupled nuclide chains. Space dependence is included by working with zone averaged fluxes

  5. DRAGON, Reactor Cell Calculation System with Burnup

    International Nuclear Information System (INIS)

    2007-01-01

    1 - Description of program or function: DRAGON is a collection of models to simulate the neutronic behavior of a unit cell or a fuel assembly in a nuclear reactor. It includes all of the functions that characterize a lattice cell code, namely: interpolation of microscopic cross sections supplied by means of standard libraries; resonance self-shielding calculations in multidimensional geometries; multigroup and multidimensional neutron flux calculations which can take into account neutron leakage; transport-transport or transport-diffusion equivalence calculations as well as editing of condensed and homogenized nuclear properties for reactor calculations; and finally isotopic depletion calculations. The user must supply cross sections. DRAGON can access directly standard microscopic cross-section libraries in the following formats: DRAGON, MATXS (TRANSX-CTR), WIMSD4, WIMS-AECL, and APOLLO. It has the capability of exchanging macroscopic and microscopic cross-section libraries with a code such as PSR-0206/TRANSX-CTR or PSR-0317/TRANSX-2 by the use of the GOXS and ISOTXS format files. Macroscopic cross sections can also be read in DRAGON via the input data stream. 2 - Method of solution: DRAGON contains a multigroup iterator conceived to control a number of different algorithms for the solution of the neutron transport equation. Each of these algorithms is presented in the form of a one-group solution procedure where the contributions from other energy groups are included in a source term. The current version, DRAGON 9 71124 (Release 3.02), which was released in January 1998, contains three such algorithms. The JPM option solves the integral transport equation using the interface current method applied to homogeneous blocks; the SYBIL option solves the integral transport equation using the collision probability method for simple one-dimensional (1-D) or two-dimensional (2-D) geometries and the interface current method for 2-D Cartesian or hexagonal assemblies; and the

  6. Ternary systems

    International Nuclear Information System (INIS)

    Kagan, D.N.; Hubberstey, P.; Barker, M.G.

    1985-01-01

    The paper reviews the experimental and theoretical studies carried out on multicomponent alkali metal systems. Solid-liquid phase equilibria studies are mainly concerned with the systems Na-K-Rb and Na-K-Cs, and data on the liquidus temperatures in these systems are presented. The thermodynamic properties of the ternary Na-K-Cs eutectic system have been determined experimentally, and the enthalpy, heat capacity and excess functions of the alloy are given. An analysis of calculational methods used in determining thermodynamic functions of ternary liquid metals systems is described. Finally, data are tabulated for the density, compressibility, saturated vapour pressure, viscosity and thermal conductivity of the ternary Na-K-Cs eutectic system. (UK)

  7. X- and γ-ray pulsations of the nearby radio-faint PSR J1741–2054

    Energy Technology Data Exchange (ETDEWEB)

    Marelli, M.; Belfiore, A.; Caraveo, P.; De Luca, A.; Salvetti, D. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy); Saz Parkinson, P. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064 (United States); Sarazin, C.; Sivakoff, G. R. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Camilo, F., E-mail: marelli@lambrate.inaf.it [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)

    2014-07-20

    We report the results of a deep XMM-Newton observation of the radio-faint γ-ray pulsar J1741–2054 and its nebula together with the analysis of five years of Fermi Large Area Telescope (LAT) data. The X-ray spectrum of the pulsar is consistent with an absorbed power law plus a blackbody, originating at least partly from the neutron star cooling. The nebular emission is consistent with that of a synchrotron pulsar wind nebula, with hints of spatial spectral variation. We extended the available Fermi LAT ephemeris and folded the γ-ray and X-ray data. We detected X-ray pulsations from the neutron star: both the thermal and non-thermal components are ∼35%-40% pulsed, with phase-aligned maxima. A sinusoid fits the thermal-folded profile well. A 10 bin phase-resolved analysis of the X-ray emission shows softening of the non-thermal spectrum during the on-pulse phases. The radio, X-ray, and γ-ray light curves are single-peaked, not phase-aligned, with the X-ray peak trailing the γ-ray peak by more than half a rotation. Spectral considerations suggest that the most probable pulsar distance is in the 0.3-1.0 kpc range, in agreement with the radio dispersion measure.

  8. X- and γ-ray pulsations of the nearby radio-faint PSR J1741–2054

    International Nuclear Information System (INIS)

    Marelli, M.; Belfiore, A.; Caraveo, P.; De Luca, A.; Salvetti, D.; Saz Parkinson, P.; Sarazin, C.; Sivakoff, G. R.; Camilo, F.

    2014-01-01

    We report the results of a deep XMM-Newton observation of the radio-faint γ-ray pulsar J1741–2054 and its nebula together with the analysis of five years of Fermi Large Area Telescope (LAT) data. The X-ray spectrum of the pulsar is consistent with an absorbed power law plus a blackbody, originating at least partly from the neutron star cooling. The nebular emission is consistent with that of a synchrotron pulsar wind nebula, with hints of spatial spectral variation. We extended the available Fermi LAT ephemeris and folded the γ-ray and X-ray data. We detected X-ray pulsations from the neutron star: both the thermal and non-thermal components are ∼35%-40% pulsed, with phase-aligned maxima. A sinusoid fits the thermal-folded profile well. A 10 bin phase-resolved analysis of the X-ray emission shows softening of the non-thermal spectrum during the on-pulse phases. The radio, X-ray, and γ-ray light curves are single-peaked, not phase-aligned, with the X-ray peak trailing the γ-ray peak by more than half a rotation. Spectral considerations suggest that the most probable pulsar distance is in the 0.3-1.0 kpc range, in agreement with the radio dispersion measure.

  9. Nuclear Weapon Effect Research at PSR (Pacific-Sierra Research Corporation) - 1983. Acute Radiation Effects on Individual Crewmember Performance

    Science.gov (United States)

    1984-08-31

    information and data from other IDP investigations. Along with the IDP Core Group, DNA staff members David L. Auton and Robert W. Young of Science and...Studies Cruier-Destroyer Group 8 ATTN: Dir of Libraries ATTN: Commander USA Military Academy David Taylor Naval Ship R&D Ctr ATTN: Doc Library ATTN: Code...ATIN: S. Shrier 2 cys ATTN: Security & Subnation Conflict Horizons Technology, Inc Rand Corp ATTN: J. Palmer ATTN: B. Bennett lIT Research Ins t itute

  10. Recommender systems

    CERN Document Server

    Kembellec, Gérald; Saleh, Imad

    2014-01-01

    Acclaimed by various content platforms (books, music, movies) and auction sites online, recommendation systems are key elements of digital strategies. If development was originally intended for the performance of information systems, the issues are now massively moved on logical optimization of the customer relationship, with the main objective to maximize potential sales. On the transdisciplinary approach, engines and recommender systems brings together contributions linking information science and communications, marketing, sociology, mathematics and computing. It deals with the understan

  11. Material Systems

    DEFF Research Database (Denmark)

    Jensen, Mads Brath; Mortensen, Henrik Rubæk; Mullins, Michael

    2009-01-01

    This paper describes and reflects upon the results of an investigative project which explores the setting up of a material system - a parametric and generative assembly consisting of and taking into consideration material properties, manufacturing constraints and geometric behavior. The project...... approaches the subject through the construction of a logic-driven system aiming to explore the possibilities of a material system that fulfills spatial, structural and performative requirements concurrently and how these are negotiated in situations where they might be conflicting....

  12. Systems Engineering

    OpenAIRE

    Vaughan, William W.

    2016-01-01

    The term “systems engineering” when entered into the Google search page, produces a significant number of results, evidence that systems engineering is recognized as being important for the success of essentially all products. Since most readers of this item will be rather well versed in documents concerning systems engineering, I have elected to share some of the points made on this subject in a document developed by the European Cooperation for Space Standardization (ECSS), a component of t...

  13. Energetic Systems

    Data.gov (United States)

    Federal Laboratory Consortium — The Energetic Systems Division provides full-spectrum energetic engineering services (project management, design, analysis, production support, in-service support,...

  14. Intelligent systems

    CERN Document Server

    Irwin, J David

    2011-01-01

    Technology has now progressed to the point that intelligent systems are replacing humans in the decision making processes as well as aiding in the solution of very complex problems. In many cases intelligent systems are already outperforming human activities. Artificial neural networks are not only capable of learning how to classify patterns, such images or sequence of events, but they can also effectively model complex nonlinear systems. Their ability to classify sequences of events is probably more popular in industrial applications where there is an inherent need to model nonlinear system

  15. Systemic darwinism.

    Science.gov (United States)

    Winther, Rasmus Grønfeldt

    2008-08-19

    Darwin's 19th century evolutionary theory of descent with modification through natural selection opened up a multidimensional and integrative conceptual space for biology. We explore three dimensions of this space: explanatory pattern, levels of selection, and degree of difference among units of the same type. Each dimension is defined by a respective pair of poles: law and narrative explanation, organismic and hierarchical selection, and variational and essentialist thinking. As a consequence of conceptual debates in the 20th century biological sciences, the poles of each pair came to be seen as mutually exclusive opposites. A significant amount of 21st century research focuses on systems (e.g., genomic, cellular, organismic, and ecological/global). Systemic Darwinism is emerging in this context. It follows a "compositional paradigm" according to which complex systems and their hierarchical networks of parts are the focus of biological investigation. Through the investigation of systems, Systemic Darwinism promises to reintegrate each dimension of Darwin's original logical space. Moreover, this ideally and potentially unified theory of biological ontology coordinates and integrates a plurality of mathematical biological theories (e.g., self-organization/structure, cladistics/history, and evolutionary genetics/function). Integrative Systemic Darwinism requires communal articulation from a plurality of perspectives. Although it is more general than these, it draws on previous advances in Systems Theory, Systems Biology, and Hierarchy Theory. Systemic Darwinism would greatly further bioengineering research and would provide a significantly deeper and more critical understanding of biological reality.

  16. Generation of pseudo-random sequences for spread spectrum systems

    Science.gov (United States)

    Moser, R.; Stover, J.

    1985-05-01

    The characteristics of pseudo random radio signal sequences (PRS) are explored. The randomness of the PSR is a matter of artificially altering the sequence of binary digits broadcast. Autocorrelations of the two sequences shifted in time, if high, determine if the signals are the same and thus allow for position identification. Cross-correlation can also be calculated between sequences. Correlations closest to zero are obtained with large volume of prime numbers in the sequences. Techniques for selecting optimal and maximal lengths for the sequences are reviewed. If the correlations are near zero in the sequences, then signal channels can accommodate multiple users. Finally, Gold codes are discussed as a technique for maximizing the code lengths.

  17. Functional analysis of the exploratory studies facility

    International Nuclear Information System (INIS)

    Duffy, M.A.; Mozhi, T.A.; Kumar, P.N.; Senderling, M.S.; Lemeshewsky, W.A.

    1993-01-01

    The 'Physical System Requirements - Exploratory Studies Facility' (PSR-ESF) was developed as part of an improved management structure and procedure initiative by the OCRWM for managing the disposal of spent nuclear fuel and high-level radioactive wastes. This paper discusses the development of the PSR-EF document. Based on a functional analysis approach, this document includes results in the form of boundary diagrams, function hierarchy trees, function description tables containing a compilation of requirements, architecture tree and tables, and functional flow diagrams. The approach used ensures the flowdown and traceability of relevant requirements for the ESF design process

  18. Assessment of policy issues in nuclear safety regulation according to circumstantial changes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Soon Heung; Lee, Byong Ho; Baek, Woon Pil; Lee, Seong Wook; Choi, Seong Soo; Roh, Chang Hyun; Lee, Kwang Gu [Korea Advanced Institute of Scienc and Technology, Taejon (Korea, Republic of)

    1998-03-15

    The objective of the work is to assess various issues in nuclear safety regulation in consideration of circumstantial changes. Emphasis is given to the safety of operating NPPs. The derivation of an effective regulation system considering 'Rhodic Safety Review (PSR)', 'operating License Renewal (LR)', 'backfitting' and 'maintenance rule' is the main objective of the first two years. It is found that those approaches should be introduced in Korea as soon as possible, with cross lingkage to maximize the effectiveness of regulation. In particular, the approaches for PSR are discussed with consultation of IAEA document and foreign practices.

  19. The discovery of an eccentric millisecond pulsar in the Galactic plane

    NARCIS (Netherlands)

    Champion, D.J.; Ransom, S.M.; Lazarus, P.; Camilo, F.; Kaspi, V.M.; Nice, D.J.; Freire, P.C.C.; Cordes, J.M.; Hessels, J.W.T.; Bassa, C.; Lorimer, D.R.; Stairs, I.H.; van Leeuwen, J.; Arzoumnian, Z.; Backer, D.C.; Bhat, N.D.R.; Chatterjee, S.; Crawford, F.; Deneva, J.S.; Faucher-Giguère, C.A.; Gaensler, B.M.; Han, J.; Jenet, F.A.; Kasian, L.; Kondratiev, V.I.; Kramer, M.; Lazio, J.; McLaughlin, M.A.; Stappers, B.W.; Venkataraman, A.; Vlemmings, W.

    2008-01-01

    The evolution of binary systems is governed by their orbital properties and the stellar density of the local environment. Studies of neutron stars in binary star systems offer unique insights into both these issues. In an Arecibo survey of the Galactic disk, we have found PSR J1903+0327, a radio

  20. Unique Stellar System Gives Einstein a Thumbs-Up

    Science.gov (United States)

    2008-07-01

    Taking advantage of a unique cosmic coincidence, astronomers have measured an effect predicted by Albert Einstein's theory of General Relativity in the extremely strong gravity of a pair of superdense neutron stars. The new data indicate that the famed physicist's 93-year-old theory has passed yet another test. Double Pulsar Graphic Artist's Conception of Double Pulsar System PSR J0737-3039A/B CREDIT: Daniel Cantin, DarwinDimensions, McGill University Click on image for more graphics. The scientists used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to make a four-year study of a double-star system unlike any other known in the Universe. The system is a pair of neutron stars, both of which are seen as pulsars that emit lighthouse-like beams of radio waves. "Of about 1700 known pulsars, this is the only case where two pulsars are in orbit around each other," said Rene Breton, a graduate student at McGill University in Montreal, Canada. In addition, the stars' orbital plane is aligned nearly perfectly with their line of sight to the Earth, so that one passes behind a doughnut-shaped region of ionized gas surrounding the other, eclipsing the signal from the pulsar in back. "Those eclipses are the key to making a measurement that could never be done before," Breton said. Einstein's 1915 theory predicted that, in a close system of two very massive objects, such as neutron stars, one object's gravitational tug, along with an effect of its spinning around its axis, should cause the spin axis of the other to wobble, or precess. Studies of other pulsars in binary systems had indicated that such wobbling occurred, but could not produce precise measurements of the amount of wobbling. "Measuring the amount of wobbling is what tests the details of Einstein's theory and gives a benchmark that any alternative gravitational theories must meet," said Scott Ransom of the National Radio Astronomy Observatory. The eclipses allowed the astronomers to pin

  1. Caste System

    OpenAIRE

    Hoff, Karla

    2016-01-01

    In standard economics, individuals are rational actors and economic forces undermine institutions that impose large inefficiencies. The persistence of the caste system is evidence of the need for psychologically more realistic models of decision-making in economics. The caste system divides South Asian society into hereditary groups whose lowest ranks are represented as innately polluted. ...

  2. Recommender systems

    OpenAIRE

    Lu L.; Medo M.; Yeung C.H.; Zhang Y.-C.; Zhang Z.-K.; Zhou T.

    2012-01-01

    The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification and comparison of different approaches are lacking, which impedes further advances. In this article...

  3. GEOMASS system

    International Nuclear Information System (INIS)

    Ohyama, Takuya; Saegusa, Hiromitsu

    2009-03-01

    As a part of the research and development regarding characterisation of deep geological environment, the GEOMASS (GEOLOGICAL MODELLING ANALYSIS AND SIMULATION SOFTWARE) system has been developed by the Japan Atomic Energy Agency in order to carry out geological and hydrogeological modelling and groundwater flow simulation and so on. The GEOMASS system integrates a commercial geological interpretation system (EarthVision), which is used for geological modelling and visualisation, with a proprietary code for groundwater flow (FracAffinity). This integrated system allows users to make rapid improvement of models as data increases. Also, it is possible to perform more realistic groundwater flow simulation due to the capability of modelling the rock mass as a continuum with discrete hydro-structural features in the rock mass. This paper consists of 'Overview of GEOMASS system', FracAffinity Theoretical Background' and 'FracAffinity User Guide' and is edited as a GEOMASS system manual. 'Overview of GEOMASS system' describes the outline of this system. 'FracAffinity Theoretical Background' describes the information of technical background of FracAffinity software. FracAffinity User Guide' describes the structure of the FracAffinity input files, the usage of FracAffinity Interface and flow-solver. Updating of the FracAffinity has been continued as needed and FracAffinity version3.3 is the latest version at present (July 2008). (author)

  4. Systems integration (automation system). System integration (automation system)

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, K; Komori, T; Fukuma, Y; Oikawa, M [Nippon Steal Corp., Tokyo (Japan)

    1991-09-26

    This paper introduces business activities on an automation systems integration (SI) started by a company in July,1988, and describes the SI concepts. The business activities include, with the CIM (unified production carried out on computers) and AMENITY (living environment) as the mainstays, a single responsibility construction ranging from consultation on structuring optimal systems for processing and assembling industries and intelligent buildings to system design, installation and after-sales services. With an SI standing on users {prime} position taken most importantly, the business starts from a planning and consultation under close coordination. On the conceptual basis of structuring optimal systems using the ompany {prime}s affluent know-hows and tools and adapting and applying with multi-vendors, open networks, centralized and distributed systems, the business is promoted with the accumulated technologies capable of realizing artificial intelligence and neural networks in its background, and supported with highly valuable business results in the past. 10 figs., 1 tab.

  5. Creative Systems

    DEFF Research Database (Denmark)

    Manelius, Anne-Mette; Beim, Anne

    2007-01-01

    Opsamling af diskussioner på konferencen og udstillingen Creative Systems i september/oktober 2007. Konferencen og Udstillingen Creative Systems sætter fokus på systemer som en positiv drivkraft i den kreative skabelsesproces. CINARK inviterede fire internationale kapaciteter, som indenfor hver...... deres felt har beskæftiget sig med udviklingen af systemer. Kieran Timberlake, markant amerikansk tegnestue; Mark West, Professor på University of Manitoba, Canada, og pioner indenfor anvendelse af tekstilforskalling til betonstøbninger; Matilda McQuaid, Arkitekturhistoriker og kurator på udstillingen...... om Extreme Textiles på amerikanske Cooper Hewit Design Museum, samt Professor Ludger Hovestadt, ved ETH, Zürich der fokuserer på udvikling og anvendelse af logaritmiske systemtilgange. Udstillingen diskuterede ud fra deres meget forskellige arbejder, det kreative potentiale i anvendelsen af systemer...

  6. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  7. Upgraded RECOVER system - CASDAC system

    International Nuclear Information System (INIS)

    Yamamoto, Yoichi; Koyama, Kinji

    1992-03-01

    The CASDAC (Containment And Surveillance Data Authenticated Communication) system has been developed by JAERI for nuclear safeguards and physical protection of nuclear material. This system was designed and constructed as an upgraded RECOVER system, design concept of which was based on the original RECOVER system and also the TRANSEAVER system. Both of them were developed several years ago as a remote monitoring system for continual verification of security and safeguards status of nuclear material. The system consists of two subsystems, one of them is a Grand Command Center (GCC) subsystem and the other is a facility subsystem. Communication between the two subsystems is controlled through the international telephone line network. Therefore all communication data are encrypted to prevent access by an unauthorized person who may intend to make a falsification, or tapping. The facility subsystem has an appropriate measure that ensure data security and reliable operation under unattended mode of operator. The software of this system is designed so as to be easily used in other different types of computers. This report describes the outline of the CASDAC system and the results of its performance test. This work has been carried out in the framework of Japan Support Programme for Agency Safeguards (JASPAS) as a project, JA-1. (author)

  8. Watchdog System

    DEFF Research Database (Denmark)

    Madsen, Tanja Kidholm Osmann; Bahnsen, Chris Holmberg; Jensen, Morten Bornø

    This deliverable is part of WP4. Overall WP4 is motivated by the need for automatic systems that can ease the task of annotating massive amounts of traffic data. Concretely this deliverable is related to WP4.2 - the watchdog system. The idea with the watchdog is to develop a system that can remov...... huge chunks of video data where no events/interactions of interest are occurring and hence let a user focus on manually annotation of only the interesting stuff....

  9. Dynamical systems

    CERN Document Server

    Sternberg, Shlomo

    2010-01-01

    Celebrated mathematician Shlomo Sternberg, a pioneer in the field of dynamical systems, created this modern one-semester introduction to the subject for his classes at Harvard University. Its wide-ranging treatment covers one-dimensional dynamics, differential equations, random walks, iterated function systems, symbolic dynamics, and Markov chains. Supplementary materials offer a variety of online components, including PowerPoint lecture slides for professors and MATLAB exercises.""Even though there are many dynamical systems books on the market, this book is bound to become a classic. The the

  10. Water systems

    International Nuclear Information System (INIS)

    Riess, R.

    1980-01-01

    The present paper describes the coolant chemistry and its consequences for 1300 MWsub(e) KWU PWR plants. Some selected systems, i.e. primary heat transport system, steam water cycle and cooling water arrangements, are chosen for this description. Various aspects of coolant chemistry regarding general corrosion, selective types of corrosion and deposits on heat transfer surfaces have been discussed. The water supply systems necessary to fulfill the requirements of the coolant chemistry are discussed as well. It has been concluded that a good operating performance can only be achieved when - beside other factors - the water chemistry has been given sufficient consideration. (orig./RW)

  11. Water systems

    International Nuclear Information System (INIS)

    Riess, R.

    1981-01-01

    The present paper describes the coolant chemistry and its consequences for 1300 MWsub(e) KWU PWR plants. Some selected systems, i.e. primary heat transport system, steam water cycle and cooling water arrangements, are chosen for this description. Various aspects of coolant chemistry regarding general corrosion, selective types of corrosion and deposits on heat transfer surface have been discussed. The water supply systems necessary to fulfill the requirements of the coolant chemistry are discussed as well. It has been concluded that a good operating performance can only be achieved when - beside other factors - the water chemistry has been given sufficient consideration. (orig./RW)

  12. Imaging system

    International Nuclear Information System (INIS)

    Froggatt, R.J.

    1981-01-01

    The invention provides a two dimensional imaging system in which a pattern of radiation falling on the system is detected to give electrical signals for each of a plurality of strips across the pattern. The detection is repeated for different orientations of the strips and the whole processed by compensated back projection. For a shadow x-ray system a plurality of strip x-ray detectors are rotated on a turntable. For lower frequencies the pattern may be rotated with a Dove prism and the strips condensed to suit smaller detectors with a cylindrical lens. (author)

  13. Kaonic systems

    Directory of Open Access Journals (Sweden)

    Oset E.

    2012-12-01

    Full Text Available I make a short review of the situation of the kaonic systems, with novel information supporting the two Λ(1405 states from the K-d → nπΣ reaction. A review is made of the K¯$ar K$NN system with recent calculations converging to smaller bindings and larger widths. Novel systems involving two kaons and one nucleon or three kaons are also reported and finally a short discussion is made of the analogous state DNN for which recent studies find a large binding and a small width.

  14. Protein synthesis rate measured with l-[1-{sup 11}C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

    Energy Technology Data Exchange (ETDEWEB)

    Plaat, B.; Mastik, M.; Molenaar, W. [Department of Pathology, University Hospital Groningen (Netherlands); Kole, A.; Vaalburg, W. [PET Centre, University Hospital Groningen (Netherlands); Hoekstra, H. [Department of Surgical Oncology, University Hospital Groningen (Netherlands)

    1999-04-29

    Protein synthesis rate (PSR) can be assessed in vivo using positron emission tomography with l-[1-{sup 11}C]tyrosine (TYR-PET). Biological activity of soft tissue sarcomas (STS) can be measured in vitro by the mitotic rate and number of proliferating cells. In STS the grade of malignancy, in which the mitotic index plays a major role, is considered to be the major standard in predicting biological tumour behaviour. This study was designed to test the validity of TYR-PET in relation to different histopathological features. In 21 patients with untreated STS, the PSR was measured using TYR-PET. The number of mitoses was counted and tumours were graded according to the grading system of Coindre et al. (Cancer 1986; 58:306-309). Proliferative activity was assessed by immunohistological detection of the Ki-67 nuclear antigen using MIB-1 monoclonal antibody. To test the association between the PSR and these tumour parameters, a correlation analysis was performed. A significant (P<0.05) correlation was found between PSR and the Ki-67 proliferation index (R = 0.54), and between PSR and mitotic rate (R = 0.64). There was no correlation between PSR and tumour grade. The present study in malignant soft tissue tumours relates in vivo tumour metabolism as established with TYR-PET to tumour activity measured in vitro and indicates that the non-invasive method of TYR-PET can estimate the mitotic and proliferative activity in STS. (orig.) With 2 figs., 2 tabs., 30 refs.

  15. Krsko periodic safety review project prioritization process

    International Nuclear Information System (INIS)

    Basic, I.; Vrbanic, I.; Spiler, J.; Lambright, J.

    2004-01-01

    Definition of a Krsko Periodic Safety Review (PSR) project is a comprehensive safety review of a plant after last ten years of operation. The objective is a verification by means of a comprehensive review using current methods that Krsko NPP remains safety when judged against current safety objectives and practices and that adequate arrangements are in place to maintain plant safety. This objective encompasses the three main criteria or goals: confirmation that the plant is as safe as originally intended, determination if there are any structures, systems or components that could limit the life of the plant in the foreseeable future, and comparison the plant against modern safety standards and to identify where improvements would be beneficial at justifiable cost. Krsko PSR project is structured in the three phases: Phase 1: Preparation of Detailed 10-years PSR Program, Phase 2: Performing of 10-years PSR Program and preparing of associated documents (2001-2003), and Phase 3: Implementation of the prioritized compensatory measures and modifications (development of associated EEAR, DMP, etc.) after agreement with the SNSA on the design, procedures and time-scales (2004-2008). This paper presents the NEK PSR results of work performed under Phase 2 focused on the ranking of safety issues and prioritization of corrective measures needed for establishing an efficient action plan. Safety issues were identified in Phase 2 during the following review processes: Periodic Safety Review (PSR) task; Krsko NPP Regulatory Compliance Program (RCP) review; Westinghouse Owner Group (WOG) catalog items screening/review; SNSA recommendations (including IAEA RAMP mission suggestions/recommendations).(author)

  16. The systems integration modeling system

    International Nuclear Information System (INIS)

    Danker, W.J.; Williams, J.R.

    1990-01-01

    This paper discusses the systems integration modeling system (SIMS), an analysis tool for the detailed evaluation of the structure and related performance of the Federal Waste Management System (FWMS) and its interface with waste generators. It's use for evaluations in support of system-level decisions as to FWMS configurations, the allocation, sizing, balancing and integration of functions among elements, and the establishment of system-preferred waste selection and sequencing methods and other operating strategies is presented. SIMS includes major analysis submodels which quantify the detailed characteristics of individual waste items, loaded casks and waste packages, simulate the detailed logistics of handling and processing discrete waste items and packages, and perform detailed cost evaluations

  17. ring system

    African Journals Online (AJOL)

    1,3,2-DIAZABORACYCLOALKANE. RING SYSTEM. Negussie Retta" and Robert H. Neilson. 'Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. Department of Chemistry, Texas Christian University.

  18. Septic Systems

    Science.gov (United States)

    The web site provides guidance and technical assistance for homeowners, government officials, industry professionals, and EPA partners about how to properly develop and manage individual onsite and community cluster systems that treat domestic wastewater.

  19. Respiratory system

    Science.gov (United States)

    Bartlett, R. G., Jr.

    1973-01-01

    The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

  20. Bubble systems

    CERN Document Server

    Avdeev, Alexander A

    2016-01-01

    This monograph presents a systematic analysis of bubble system mathematics, using the mechanics of two-phase systems in non-equilibrium as the scope of analysis. The author introduces the thermodynamic foundations of bubble systems, ranging from the fundamental starting points to current research challenges. This book addresses a range of topics, including description methods of multi-phase systems, boundary and initial conditions as well as coupling requirements at the phase boundary. Moreover, it presents a detailed study of the basic problems of bubble dynamics in a liquid mass: growth (dynamically and thermally controlled), collapse, bubble pulsations, bubble rise and breakup. Special emphasis is placed on bubble dynamics in turbulent flows. The analysis results are used to write integral equations governing the rate of vapor generation (condensation) in non-equilibrium flows, thus creating a basis for solving a number of practical problems. This book is the first to present a comprehensive theory of boil...

  1. Systems Biology

    Indian Academy of Sciences (India)

    IAS Admin

    study and understand the function of biological systems, particu- larly, the response of such .... understand the organisation and behaviour of prokaryotic sys- tems. ... relationship of the structure of a target molecule to its ability to bind a certain ...

  2. Bricks / Systems

    DEFF Research Database (Denmark)

    At first glance, this book may appear eclectic. It contains writings from architectural practice in a language and structure based on subjective views and experiences, combined with research contributions based on systematic design investigations of discrete computational systems. Discussions range......, and it aims to illustrate and identify new modes of working in architecture, particularly with regards to brickwork and other complex systems of modular assemblies, whether physical or digital....

  3. Expert Systems

    OpenAIRE

    Lucas, P.J.F.

    2005-01-01

    Expert systems mimic the problem-solving activity of human experts in specialized domains by capturing and representing expert knowledge. Expert systems include a knowledge base, an inference engine that derives conclusions from the knowledge, and a user interface. Knowledge may be stored as if-then rules, orusing other formalisms such as frames and predicate logic. Uncertain knowledge may be represented using certainty factors, Bayesian networks, Dempster-Shafer belief functions, or fuzzy se...

  4. Nanorobotic Systems

    Directory of Open Access Journals (Sweden)

    Lixin Dong

    2008-11-01

    Full Text Available Two strategies towards the realization of nanotechnology have been presented, i.e., top-down and bottom up. The former one is mainly based on nanofabrication and includes technologies such as nano-lithography, nano-imprint, and etching. Presently, they are still 2D fabrication processes with low resolution. The later one is an assembly-based technique. At present, it includes such items as self-assembly, dip-pen lithography, and directed self-assembly. These techniques can generate regular nano patterns in large scales. To fabricate 3D complex nano devices there are still no effective ways by so far. Here we show our effort on the development of a nano laboratory, a prototype nanomanufacturing system, based on nanorobotic manipulations. In which, we take a hybrid strategy as shown in Fig. 1. In this system, nano fabrication and nano assembly can be performed in an arbitrary order to construct nano building blocks and finally nano devices. The most important feature in this system is that the products can be fed back into the system to shrink the system part by part leading to nanorobots. Property characterization can be performed in each intermediate process. Due to the nanorobotic manipulation system, dynamic measurement can be performed rather than conventional static observations.

  5. VENTURE-PC 1.1, Reactor Analysis System with Sensitivity and Burnup

    International Nuclear Information System (INIS)

    2002-01-01

    1 - Description of program or function: The VENTURE program solves the usual neutronics eigenvalue, adjoint, fixed source, and criticality search problems. It treats up to three dimensions, maps power density, and does first-order perturbation analysis at the macroscopic cross section level. The BURNER code solves the nuclide chain equations to estimate the nuclide concentrations and burnup at the end of an exposure time or after a shutdown period. This package is based on the CCC-459/BOLD VENTURE IV code system developed at Oak Ridge National Laboratory. In January 1989 the University of Cincinnati contributed the first VENTURE-PC package to RSICC's collection. It was a subset of the mainframe version consisting of the VENTURE and BURNER modules plus several processing modules. VENTURE-PC was distributed as CCC-459 until July 1997 when a new version (with updated source code compatible with newer FORTRAN-77 compilers, some revisions, and extensions to solve much larger problems) was contributed by Argonne National Laboratory. The principle code modules included in the VENTURE-PC system are: VENTURE: Multigroup neutronics finite-difference diffusion theory. BURNER: Depletion calculation for reactor core analysis. Other modules within VENTURE-PC are: DVENTR: Venture input processor; DCRSPR: Neutron cross section processor; DUTLIN: Control file (CNTRL) input processor; DCMACR: Citation format cross section input processor; CRXSPR: Cross section processor; DENMAN: Fuel repositioning module. In August of 1999, Argonne again contributed an updated version of the code which overcomes problem size constraints caused by binary record length limits inherent to the Fortran 90 compiler. The need for long records is detected and avoided by sub-blocking them. Also, the latest Fortran 95 compiler offers substantial speed gains on the newest processors. The source code is updated to be compatible with either Fortran 90 or Fortran 95. In August 2002, the package was updated with

  6. Fiscal system analysis - contractual systems

    International Nuclear Information System (INIS)

    Kaiser, M.J.

    2006-01-01

    Production sharing contracts are one of the most popular forms of contractual system used in petroleum agreements around the world, but the manner in which the fiscal terms and contract parameters impact system measures is complicated and not well understood. The purpose of this paper is to quantify the influence of private and market uncertainty in contractual fiscal systems. A meta-modelling approach is employed that couples the results of a simulation model with regression analysis to construct numerical functionals that quantify the fiscal regime. Relationships are derived that specify how the present value, rate of return, and take statistics vary as a function of the system parameters. The deepwater Girassol field development in Angola is taken as a case study. (author)

  7. Tomographic retrieval of cloud liquid water fields from a single scanning microwave radiometer aboard a moving platform – Part 1: Field trial results from the Wakasa Bay experiment

    Directory of Open Access Journals (Sweden)

    D. Huang

    2010-07-01

    Full Text Available Tomographic methods offer great potential for retrieving three-dimensional spatial distributions of cloud liquid water from radiometric observations by passive microwave sensors. Fixed tomographic systems require multiple radiometers, while mobile systems can use just a single radiometer. Part 1 (this paper examines the results from a limited cloud tomography trial with a single-radiometer airborne system carried out as part of the 2003 AMSR-E validation campaign over Wakasa Bay of the Sea of Japan. During this trial, the Polarimetric Scanning Radiometer (PSR and Microwave Imaging Radiometer (MIR aboard the NASA P-3 research aircraft provided a useful dataset for testing the cloud tomography method over a system of low-level clouds. We do tomographic retrievals with a constrained inversion algorithm using three configurations: PSR, MIR, and combined PSR and MIR data. The liquid water paths from the PSR retrieval are consistent with those from the MIR retrieval. The retrieved cloud field based on the combined data appears to be physically plausible and consistent with the cloud image obtained by a cloud radar. We find that some vertically-uniform clouds appear at high altitudes in the retrieved field where the radar shows clear sky. This is likely due to the sub-optimal data collection strategy. This sets the stage for Part 2 of this study that aims to define optimal data collection strategies using observation system simulation experiments.

  8. Reactor system

    International Nuclear Information System (INIS)

    Miyano, Hiroshi; Narabayashi, Naoshi.

    1990-01-01

    The represent invention concerns a reactor system with improved water injection means to a pressure vessel of a BWR type reactor. A steam pump is connected to a heat removing system pipeline, a high pressure water injection system pipeline and a low pressure water injection system pipeline for injecting water into the pressure vessel. A pump actuation pipeline is disposed being branched from a main steam pump or a steam relieaf pipeline system, through which steams are supplied to actuate the steam pump and supply cooling water into the pressure vessel thereby cooling the reactor core. The steam pump converts the heat energy into the kinetic energy and elevates the pressure of water to a level higher than the pressure of the steams supplied by way of a pressure-elevating diffuser. Cooling water can be supplied to the pressure vessel by the pressure elevation. This can surely inject cooling water into the pressure vessel upon loss of coolant accident or in a case if reactor scram is necessary, without using an additional power source. (I.N.)

  9. Biomechanical Analysis of an Expandable Lumbar Interbody Spacer.

    Science.gov (United States)

    Soriano-Baron, Hector; Newcomb, Anna G U S; Malhotra, Devika; Palma, Atilio E; Martinez-Del-Campo, Eduardo; Crawford, Neil R; Theodore, Nicholas; Kelly, Brian P; Kaibara, Taro

    2018-06-01

    Recently developed expandable interbody spacers are widely accepted in spinal surgery; however, the resulting biomechanical effects of their use have not yet been fully studied. We analyzed the biomechanical effects of an expandable polyetheretherketone interbody spacer inserted through a bilateral posterior approach with and without different modalities of posterior augmentation. Biomechanical nondestructive flexibility testing was performed in 7 human cadaveric lumbar (L2-L5) specimens followed by axial compressive loading. Each specimen was tested under 6 conditions: 1) intact, 2) bilateral L3-L4 cortical screw/rod (CSR) alone, 3) WaveD alone, 4) WaveD + CSR, 5) WaveD + bilateral L3-L4 pedicle screw/rod (PSR), and 6) WaveD + CSR/PSR, where CSR/PSR was a hybrid construct comprising bilateral cortical-level L3 and pedicle-level L4 screws interconnected by rods. The range of motion (ROM) with the interbody spacer alone decreased significantly compared with the intact condition during flexion-extension (P = 0.02) but not during lateral bending or axial rotation (P ≥ 0.19). The addition of CSR or PSR to the interbody spacer alone condition significantly decreased the ROM compared with the interbody spacer alone (P ≤ 0.002); and WaveD + CSR, WaveD + PSR, and WaveD + CSR/PSR (hybrid) (P ≥ 0.29) did not differ. The axial compressive stiffness (resistance to change in foraminal height during compressive loading) with the interbody spacer alone did not differ from the intact condition (P = 0.96), whereas WaveD + posterior instrumentation significantly increased compressive stiffness compared with the intact condition and the interbody spacer alone (P ≤ 0.001). The WaveD alone significantly reduced ROM during flexion-extension while maintaining the axial compressive stiffness. CSR, PSR, and CSR/PSR hybrid constructs were all effective in augmenting the expandable interbody spacer system and improving its stability. Copyright © 2018 Elsevier Inc. All

  10. ARAC system

    International Nuclear Information System (INIS)

    Kelly, M.F.; Wyman, R.H.

    1975-01-01

    In spite of the remarkable safety record of the nuclear industry as a whole, recent public concern over the potential impact of the industry's accelerated growth has prompted ERDA to expand its emergency response procedures. The Atmospheric Release Advisory Capability, ARAC, is a computer communications system designed to enhance the existing emergency response capability of ERDA nuclear facilities. ARAC will add at least two new functions to this capability: centralized, real-time data acquisition and storage, and simulation of the long range atmospheric transport of hazardous materials. To perform these functions, ARAC employs four major sub-systems or facilities: the site facility, the central facility, the global weather center and the regional model. The system has been under development for the past two years at the Lawrence Livermore Laboratory of the University of California

  11. Microbiology System

    Science.gov (United States)

    1992-01-01

    Technology originating in a NASA-sponsored study of the measurement of microbial growth in zero gravity led to the development of Biomerieux Vitek, Inc.'s VITEK system. VITEK provides a physician with accurate diagnostic information and identifies the most effective medication. Test cards are employed to identify organisms and determine susceptibility to antibiotics. A photo-optical scanner scans the card and monitors changes in the growth of cells contained within the card. There are two configurations - VITEK and VITEK JR as well as VIDAS, a companion system that detects bacteria, viruses, etc. from patient specimens. The company was originally created by McDonnell Douglas, the NASA contractor.

  12. Spin systems

    CERN Document Server

    Caspers, W J

    1989-01-01

    This book is about spin systems as models for magnetic materials, especially antiferromagnetic lattices. Spin-systems are well-defined models, for which, in special cases, exact properties may be derived. These special cases are for the greater part, one- dimensional and restricted in their applicability, but they may give insight into general properties that also exist in higher dimension. This work pays special attention to qualitative differences between spin lattices of different dimensions. It also replaces the traditional picture of an (ordered) antiferromagnetic state of a Heisenberg sy

  13. Distributed systems

    CERN Document Server

    Van Steen, Maarten

    2017-01-01

    For this third edition of "Distributed Systems," the material has been thoroughly revised and extended, integrating principles and paradigms into nine chapters: 1. Introduction 2. Architectures 3. Processes 4. Communication 5. Naming 6. Coordination 7. Replication 8. Fault tolerance 9. Security A separation has been made between basic material and more specific subjects. The latter have been organized into boxed sections, which may be skipped on first reading. To assist in understanding the more algorithmic parts, example programs in Python have been included. The examples in the book leave out many details for readability, but the complete code is available through the book's Website, hosted at www.distributed-systems.net.

  14. Planetesimals around nearby millisecond pulsars

    International Nuclear Information System (INIS)

    Chakrabarti, S.K.

    1992-05-01

    We predict that it is possible to observe line emissions of OH, CN and C 2 from the planetesimals around some of the nearby millisecond pulsars, such as PSR1257+12. Observation of these lines will provide an independent test of either an existing planetary system or one which is in the process of formation. (author). 11 refs, 1 tab

  15. Verification of f(R-gravity in binary pulsars

    Directory of Open Access Journals (Sweden)

    Dyadina Polina

    2016-01-01

    Full Text Available We develop the parameterized post-Keplerian approach for class of analytic f (R-gravity models. Using the double binary pulsar system PSR J0737-3039 data we obtain restrictions on the parameters of this class of f (R-models and show that f (R-gravity is not ruled out by the observations in strong field regime.

  16. Immune System

    Science.gov (United States)

    ... of the Immune System Print en español El sistema inmunitario Whether you're stomping through the showers ... of Use Notice of Nondiscrimination Visit the Nemours Web site. Note: All information on TeensHealth® is for ...

  17. Operating Systems

    Indian Academy of Sciences (India)

    areas in which this type is useful are multimedia, virtual reality, and advanced scientific projects such as undersea exploration and planetary rovers. Because of the expanded uses for soft real-time functionality, it is finding its way into most current operating systems, including major versions of Unix and Windows NT OS.

  18. Barrier Systems

    NARCIS (Netherlands)

    Heteren, S. van

    2015-01-01

    Barrier-system dynamics are a function of antecedent topography and substrate lithology, Relative sea-level (RSL) changes, sediment availability and type, climate, vegetation type and cover, and various aero- and hydrodynamic processes during fair-weather conditions and extreme events. Global change

  19. Systems Science

    Science.gov (United States)

    Christakis, Alexander; Hammond, Debora; Jackson, Michael; Laszlo, Alexander; Mitroff, Ian; Snowden, Dave; Troncale, Len; Carr-Chellman, Alison; Spector, J. Michael; Wilson, Brent

    2013-01-01

    Scholars representing the field of systems science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Alexander Christakis, Debora Hammond, Michael Jackson, Alexander Laszlo, Ian Mitroff, Dave…

  20. Transport system

    NARCIS (Netherlands)

    Drenth, K.F.

    1999-01-01

    The transport system comprises at least one road surface (2) and at least one vehicle (4) on wheels (6). The road surface (2) has a substantially bowl-shaped cross section and the vehicle (4) is designed so that the wheels (6) run directly on the road surface (2) while the road surface (2) acts as a

  1. Quorum Systems

    DEFF Research Database (Denmark)

    Wattenhofer, Roger; Förster, Klaus-Tycho

    2016-01-01

    What happens if a single server is no longer powerful enough to service all your customers? The obvious choice is to add more servers and to use the majority approach (e.g. Paxos, Chapter 2) to guarantee consistency. However, even if you buy one million servers, a client still has to access more ...... study the theory behind overlapping sets, known as quorum systems....

  2. System Dynamics

    Science.gov (United States)

    Morecroft, John

    System dynamics is an approach for thinking about and simulating situations and organisations of all kinds and sizes by visualising how the elements fit together, interact and change over time. This chapter, written by John Morecroft, describes modern system dynamics which retains the fundamentals developed in the 1950s by Jay W. Forrester of the MIT Sloan School of Management. It looks at feedback loops and time delays that affect system behaviour in a non-linear way, and illustrates how dynamic behaviour depends upon feedback loop structures. It also recognises improvements as part of the ongoing process of managing a situation in order to achieve goals. Significantly it recognises the importance of context, and practitioner skills. Feedback systems thinking views problems and solutions as being intertwined. The main concepts and tools: feedback structure and behaviour, causal loop diagrams, dynamics, are practically illustrated in a wide variety of contexts from a hot water shower through to a symphony orchestra and the practical application of the approach is described through several real examples of its use for strategic planning and evaluation.

  3. System Description:

    DEFF Research Database (Denmark)

    Schürmann, Carsten; Poswolsky, Adam

    2009-01-01

    Delphin is a functional programming language [Adam Poswolsky and Carsten Schürmann. Practical programming with higher-order encodings and dependent types. In European Symposium on Programming (ESOP), 2008] utilizing dependent higher-order datatypes. Delphin's two-level type-system cleanly separates...

  4. Immune System

    Science.gov (United States)

    A properly functioning immune system is essential to good health. It defends the body against infectious agents and in some cases tumor cells. Individuals with immune deficiencies resulting from genetic defects, diseases (e.g., AIDS, leukemia), or drug therapies are more suscepti...

  5. Bioenergy systems

    International Nuclear Information System (INIS)

    Mitchell, C.P.

    1997-01-01

    The objective of this paper is to demonstrate that a bioenergy system has to be considered as an integrated process in which each stage or step interacts with other steps in the overall process. There are a number of stages in the supply and conversion of woody biomass for energy. Each step in the chain has implications for the next step and for overall system efficiency. The resource can take many forms and will have varying physical and chemical characteristics which will influence the efficiency and cost of conversion. The point in the supply chain at which size and moisture content is reduced and the manner in which it is done is influential in determining feedstock delivered cost and overall system costs. To illustrate the interactions within the overall system, the influence of the nature, size and moisture content of delivered feedstocks on costs of generating electricity via thermal conversion processes is examined using a model developed to investigate the inter-relationships between the stages in the supply chain. (author)

  6. Urogenital system

    International Nuclear Information System (INIS)

    Hamm, B.; Asbach, P.; Beyersdorff, D.; Hein, P.; Zaspel, U.

    2007-01-01

    The book is focussed on the radiological diagnostics of diseases in the urogential system. The description of the specific diseases, the identification by modern imaging techniques, the interpretation of examinatory results and therapeutic options are systematically treated in 4 chapters: kidney and adrenal glands, urinary tract, male genitals, female genitals

  7. Mirror systems.

    Science.gov (United States)

    Fogassi, Leonardo; Ferrari, Pier Francesco

    2011-01-01

    Mirror neurons are a class of visuomotor neurons, discovered in the monkey premotor cortex and in an anatomically connected area of the inferior parietal lobule, that activate both during action execution and action observation. They constitute a circuit dedicated to match actions made by others with the internal motor representations of the observer. It has been proposed that this matching system enables individuals to understand others' behavior and motor intentions. Here we will describe the main features of mirror neurons in monkeys. Then we will present evidence of the presence of a mirror system in humans and of its involvement in several social-cognitive functions, such as imitation, intention, and emotion understanding. This system may have several implications at a cognitive level and could be linked to specific social deficits in humans such as autism. Recent investigations addressed the issue of the plasticity of the mirror neuron system in both monkeys and humans, suggesting also their possible use in rehabilitation. WIREs Cogn Sci 2011 2 22-38 DOI: 10.1002/wcs.89 For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.

  8. Systemic Planning

    DEFF Research Database (Denmark)

    Leleur, Steen

    This book presents principles and methodology for planning in a complex world. It sets out a so-called systemic approach to planning, among other things, by applying “hard” and “soft” methodologies and methods in combination. The book is written for Ph.D and graduate students in engineering...

  9. Energy systems

    International Nuclear Information System (INIS)

    Haefele, W.

    1974-01-01

    Up to the present the production, transmission and distribution of energy has been considered mostly as a fragmented problem; at best only subsystems have been considered. Today the scale of energy utilization is increasing rapidly, and correspondingly, the reliance of societies on energy. Such strong quantitative increases influence the qualitative nature of energy utilization in most of its aspects. Resources, reserves, reliability and environment are among the key words that may characterize the change in the nature of the energy utilization problem. Energy can no longer be considered an isolated technical and economical problem, rather it is embedded in the ecosphere and the society-technology complex. Restraints and boundary conditions have to be taken into account with the same degree of attention as in traditional technical problems, for example a steam turbine. This results in a strong degree of interweaving. Further, the purpose of providing energy becomes more visible, that is, to make survival possible in a civilized and highly populated world on a finite globe. Because of such interweaving and finiteness it is felt that energy should be considered as a system and therefore the term 'energy systems' is used. The production of energy is only one component of such a system; the handling of energy and the embedding of energy into the global and social complex in terms of ecology, economy, risks and resources are of similar importance. he systems approach to the energy problem needs more explanation. This paper is meant to give an outline of the underlying problems and it is hoped that by so doing the wide range of sometimes confusing voices about energy can be better understood. Such confusion starts already with the term 'energy crisis'. Is there an energy crisis or not? Much future work is required to tackle the problems of energy systems. This paper can only marginally help in that respect. But it is hoped that it will help understand the scope of the

  10. Energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Haefele, W [Nuclear Research Centre, Applied Systems Analysis and Reactor Physics, Karlsruhe (Germany); International Institute for Applied Systems Analysis, Laxenburg (Austria)

    1974-07-01

    Up to the present the production, transmission and distribution of energy has been considered mostly as a fragmented problem; at best only subsystems have been considered. Today the scale of energy utilization is increasing rapidly, and correspondingly, the reliance of societies on energy. Such strong quantitative increases influence the qualitative nature of energy utilization in most of its aspects. Resources, reserves, reliability and environment are among the key words that may characterize the change in the nature of the energy utilization problem. Energy can no longer be considered an isolated technical and economical problem, rather it is embedded in the ecosphere and the society-technology complex. Restraints and boundary conditions have to be taken into account with the same degree of attention as in traditional technical problems, for example a steam turbine. This results in a strong degree of interweaving. Further, the purpose of providing energy becomes more visible, that is, to make survival possible in a civilized and highly populated world on a finite globe. Because of such interweaving and finiteness it is felt that energy should be considered as a system and therefore the term 'energy systems' is used. The production of energy is only one component of such a system; the handling of energy and the embedding of energy into the global and social complex in terms of ecology, economy, risks and resources are of similar importance. he systems approach to the energy problem needs more explanation. This paper is meant to give an outline of the underlying problems and it is hoped that by so doing the wide range of sometimes confusing voices about energy can be better understood. Such confusion starts already with the term 'energy crisis'. Is there an energy crisis or not? Much future work is required to tackle the problems of energy systems. This paper can only marginally help in that respect. But it is hoped that it will help understand the scope of the

  11. PALFA Discovery of a Highly Relativistic Double Neutron Star Binary

    Science.gov (United States)

    Stovall, K.; Freire, P. C. C.; Chatterjee, S.; Demorest, P. B.; Lorimer, D. R.; McLaughlin, M. A.; Pol, N.; van Leeuwen, J.; Wharton, R. S.; Allen, B.; Boyce, M.; Brazier, A.; Caballero, K.; Camilo, F.; Camuccio, R.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Ferdman, R. D.; Hessels, J. W. T.; Jenet, F. A.; Kaspi, V. M.; Knispel, B.; Lazarus, P.; Lynch, R.; Parent, E.; Patel, C.; Pleunis, Z.; Ransom, S. M.; Scholz, P.; Seymour, A.; Siemens, X.; Stairs, I. H.; Swiggum, J.; Zhu, W. W.

    2018-02-01

    We report the discovery and initial follow-up of a double neutron star (DNS) system, PSR J1946+2052, with the Arecibo L-Band Feed Array pulsar (PALFA) survey. PSR J1946+2052 is a 17 ms pulsar in a 1.88 hr, eccentric (e = 0.06) orbit with a ≳1.2 M ⊙ companion. We have used the Jansky Very Large Array to localize PSR J1946+2052 to a precision of 0.″09 using a new phase binning mode. We have searched multiwavelength catalogs for coincident sources but did not find any counterparts. The improved position enabled a measurement of the spin period derivative of the pulsar (\\dot{P}=9+/- 2× {10}-19); the small inferred magnetic field strength at the surface (B S = 4 × 109 G) indicates that this pulsar has been recycled. This and the orbital eccentricity lead to the conclusion that PSR J1946+2052 is in a DNS system. Among all known radio pulsars in DNS systems, PSR J1946+2052 has the shortest orbital period and the shortest estimated merger timescale, 46 Myr; at that time it will display the largest spin effects on gravitational-wave waveforms of any such system discovered to date. We have measured the advance of periastron passage for this system, \\dot{ω }=25.6+/- 0.3 \\deg {yr}}-1, implying a total system mass of only 2.50 ± 0.04 M ⊙, so it is among the lowest-mass DNS systems. This total mass measurement combined with the minimum companion mass constrains the pulsar mass to ≲1.3 M ⊙.

  12. TUBO system

    International Nuclear Information System (INIS)

    Barbosa, H.J.C.; Guerreiro, J.N.C.; Toledo, E.M.

    1980-01-01

    Proceedings recently incorporated to TUBO system like the seismic analysis and the stress verification acccording to ASME-Boiler Rule and Pressure Vessel Code-section III are presented. The seismic analysis comprehend the consideration of uniform motion of the support, its multiple excitation, and the attainment of the spectral response for both cases. The module for stress verification uses stresses resulting fromthe combination of the loads specified by the user, in the automatic verification of permissible stresses for the pipings class 1 and 2, based on criteria NB-3650 and NC-3650 of ASME. The implementation of these proceedings in the TUBO system are discussed and a numerical example that covers the different phases of a stress analysis in a piping is presented [pt

  13. Solar Systems

    Science.gov (United States)

    1979-01-01

    The solar collectors shown are elements of domestic solar hot water systems produced by Solar One Ltd., Virginia Beach, Virginia. Design of these systems benefited from technical expertise provided Solar One by NASA's Langley Research Center. The company obtained a NASA technical support package describing the d e sign and operation of solar heating equipment in NASA's Tech House, a demonstration project in which aerospace and commercial building technology are combined in an energy- efficient home. Solar One received further assistance through personal contact with Langley solar experts. The company reports that the technical information provided by NASA influenced Solar One's panel design, its selection of a long-life panel coating which increases solar collection efficiency, and the method adopted for protecting solar collectors from freezing conditions.

  14. Bilateral system. The ABACC system

    International Nuclear Information System (INIS)

    Nicolas, Ruben O.

    2001-01-01

    After relating the antecedents of the creation of the Brazilian-Argentine Agency for the Accounting and Control of Nuclear Materials (ABACC), the paper describes the common system of accounting and control set up by Argentina and Brazil. The organization of ABACC is also outlined

  15. Physical system requirements: Overall system

    International Nuclear Information System (INIS)

    1992-01-01

    The Nuclear Waste Policy Act (NWPA) of 1982 assigned to the Department of Energy (DOE) the responsibility for managing the disposal of spent nuclear fuel and high-level radioactive waste and established the Office of Civilian Radioactive Waste Management (OCRWM) for that purpose. The Secretary of Energy, in his November 1989 report to Congress (DOE/RW-0247), announced three new initiatives for conduct of the Civilian Radioactive Waste Management (CRWM) program. One of these initiatives was to establish improved management structure and procedures. In response, OCRWM performed a management study and the Direct subsequently issued the Management Systems Improvement Strategy (MSIS) on August 10, 1990, calling for a rigorous implementation of systems engineering principles with a special emphasis on functional analysis. This approach establishes a framework for integrating the program management efforts with the technical requirements analysis into a single, unified, and consistent program. The functional analysis approach recognizes that just the facilities and equipment comprising the physical waste management system must perform certain functions, so must certain programmatic and management functions be performed within the program in order to successfully bring the physical system into being

  16. Security system

    Science.gov (United States)

    Baumann, Mark J.; Kuca, Michal; Aragon, Mona L.

    2016-02-02

    A security system includes a structure having a structural surface. The structure is sized to contain an asset therein and configured to provide a forceful breaching delay. The structure has an opening formed therein to permit predetermined access to the asset contained within the structure. The structure includes intrusion detection features within or associated with the structure that are activated in response to at least a partial breach of the structure.

  17. Cardiovascular system

    International Nuclear Information System (INIS)

    Soulen, R.L.; Grosh, J.

    1984-01-01

    Invasive cardiovascular diagnostic procedures involve a finite risk and therefore can be recommended only when the benefit appears to exceed the risk by a substantial margin. The risk/benefit ratio varies not only with the procedure concerned but with the status of the vascular system, concomitant diseases, and the risks of both the suspected illness and its treatment. The risks inherent in the procedures per se are detailed in the sections to follow

  18. Priority Systems

    OpenAIRE

    Gössler , Gregor; Sifakis , Joseph

    2004-01-01

    Projet POP_ART; We present a framework for the incremental construction of deadlock-free systems meeting given safety properties. The framework borrows concepts and basic results from the controller synthesis paradigm by considering a step in the construction process as a controller synthesis problem. We show that priorities are expressive enough to represent restrictions induced by deadlock-free controllers preserving safety properties. We define a correspondence between such restrictions an...

  19. Imaging system

    International Nuclear Information System (INIS)

    Rushbrooke, J.G.; Ansorge, R.E.

    1987-01-01

    A moving object such as a container on a conveyor belt is imaged by an optical system onto a charge coupled device array in which the lines of the array are arranged perpendicular to the direction of motion of the object. The speed of movement of the object is sensed to generate electrical signals which are processed to provide shift signals enabling the shifting of data row to row in the array in synchronism with the movement of the container. The electrical charge associated with a given point on the array is transferred from one line to the other until it appears at the last line of the array, from which it is read out in known manner in conjunction with all other electrical charges associated with the row of charge coupled devices in the last line of the array. Due to the integrating effect achieved, the aperture of the imaging system can be much smaller than otherwise would be required, and/or the level of light illumination can be reduced. The imaging system can be applied to X-ray inspection devices, aerial surveillance or scanning of moving documents in copying processes. (author)

  20. Braking system

    Science.gov (United States)

    Norgren, D.U.

    1982-09-23

    A balanced braking system comprising a plurality of braking assemblies located about a member to be braked. Each of the braking assemblies consists of a spring biased piston of a first material fitted into a body of a different material which has a greater contraction upon cooling than the piston material. The piston is provided with a recessed head portion over which is positioned a diaphragm and forming a space therebetween to which is connected a pressurized fluid supply. The diaphragm is controlled by the fluid in the space to contact or withdraw from the member to be braked. A cooling means causes the body within which the piston is fitted to contract more than the piston, producing a tight shrink fit therebetween. The braking system is particularly applicable for selectively braking an arbor of an electron microscope which immobilizes, for example, a vertically adjustable low temperature specimen holder during observation. The system provides balanced braking forces which can be easily removed and re-established with minimal disturbance to arbor location.

  1. Protecting information in systems of systems

    NARCIS (Netherlands)

    Trivellato, D.

    2012-01-01

    Systems of systems are coalitions of autonomous and heterogeneous systems that collaborate to achieve a common goal. The component systems of a system of systems often belong to different security domains, which are governed by different authorities (hereafter called parties). Furthermore, systems

  2. Dynamical systems

    CERN Document Server

    Birkhoff, George D

    1927-01-01

    His research in dynamics constitutes the middle period of Birkhoff's scientific career, that of maturity and greatest power. -Yearbook of the American Philosophical Society The author's great book€¦is well known to all, and the diverse active modern developments in mathematics which have been inspired by this volume bear the most eloquent testimony to its quality and influence. -Zentralblatt MATH In 1927, G. D. Birkhoff wrote a remarkable treatise on the theory of dynamical systems that would inspire many later mathematicians to do great work. To a large extent, Birkhoff was writing about his o

  3. Nuclear systems

    CERN Document Server

    Todreas, Neil E

    2011-01-01

    Principal Characteristics of Power ReactorsIntroductionPower CyclesPrimary Coolant SystemsReactor CoresFuel AssembliesAdvanced Water- and Gas-Cooled Reactors (Generation III And III+)Advanced Thermal and Fast Neutron Spectrum Reactors (Generation IV)ReferencesProblemsThermal Design Principles and ApplicationIntroductionOverall Plant Characteristics Influenced by Thermal Hydraulic ConsiderationsEnergy Production and Transfer ParametersThermal Design LimitsThermal Design MarginFigures of Merit for Core Thermal PerformanceThe Inverted Fuel ArrayThe Equivalent Annulus ApproximationReferencesProble

  4. Videobasierte Systeme

    Science.gov (United States)

    Knoll, Peter

    Videosensoren spielen für Fahrerassistenz systeme eine zentrale Rolle, da sie die Interpretation visueller Informationen (Objektklassifikation) gezielt unterstützen. Im Heckbereich kann die Video sensorik in der einfachsten Variante die ultraschallbasierte Einparkhilfe bei Einpark- und Rangiervorgängen unterstützen. Beim Nachtsichtsystem NightVision wird das mit Infrarotlicht angestrahlte Umfeld vor dem Fahrzeug mit einer Frontkamera aufgenommen und im Fahrzeugcockpit auf einem Display dem Fahrer angezeigt (s. Nachtsichtsysteme). Andere Fahrerassistenzsysteme verarbeiten die Videosignale und generieren daraus gezielt Informationen, die für eigenständige Funktionen (z. B. Spurverlassenswarner) oder aber als Zusatzinformation für andere Funktionen ausgewertet werden (Sensordatenfusion).

  5. Relaxation System

    Science.gov (United States)

    1987-01-01

    Environ Corporation's relaxation system is built around a body lounge, a kind of super easy chair that incorporates sensory devices. Computer controlled enclosure provides filtered ionized air to create a feeling of invigoration, enhanced by mood changing aromas. Occupant is also surrounded by multidimensional audio and the lighting is programmed to change colors, patterns, and intensity periodically. These and other sensory stimulators are designed to provide an environment in which the learning process is stimulated, because research has proven that while an individual is in a deep state of relaxation, the mind is more receptive to new information.

  6. Bearing system

    Science.gov (United States)

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  7. Propulsion Systems

    Science.gov (United States)

    2011-03-31

    stand.    CV CS x dAvvdVov dt d F   (18-1) Where  denotes density and vx is the velocity in the x-direction. The first term on the...by  but to avoid confusion with  from Eqs. 18-7 to 10, it is denoted k in this formula . Ru is the universal gas constant (8.314472 J/mol K), pe is...Russian Federation Used on Phobos spacecraft as main engines 74 1.03 NTO/ UDMH 13.73-19.61 316-325 Orbital Maneuvering System 1 Aerojet Shuttle

  8. Expert Systems: What Is an Expert System?

    Science.gov (United States)

    Duval, Beverly K.; Main, Linda

    1994-01-01

    Describes expert systems and discusses their use in libraries. Highlights include parts of an expert system; expert system shells; an example of how to build an expert system; a bibliography of 34 sources of information on expert systems in libraries; and a list of 10 expert system shells used in libraries. (Contains five references.) (LRW)

  9. System analysis and design

    International Nuclear Information System (INIS)

    Son, Seung Hui

    2004-02-01

    This book deals with information technology and business process, information system architecture, methods of system development, plan on system development like problem analysis and feasibility analysis, cases for system development, comprehension of analysis of users demands, analysis of users demands using traditional analysis, users demands analysis using integrated information system architecture, system design using integrated information system architecture, system implementation, and system maintenance.

  10. Posting system

    International Nuclear Information System (INIS)

    Hackney, S.

    1983-01-01

    A system for posting hazardous materials into and out of an enclosure, such as a glovebox, through a port in a wall of the enclosure. The port is normally closed by a door which cooperates with a removable end closure, on a container or the like when the latter is presented to and secured at the port. The container is secured in position at the port by means of a rotatable coupling ring. A single interlock ensures that the door cannot be opened in the absence of a container at the port and also that the container cannot be removed from the port when the door is open. In place of the container, a glove secured to a rigid sleeve may be used to enable the operator to perform a work function within the glovebox. (author)

  11. hydrothermal systems

    Directory of Open Access Journals (Sweden)

    L. Bayón

    2002-01-01

    Full Text Available In this paper, we revise the classical formulation of the problem depriving it of the concepts that are superfluous from the mathematical point of view. We observe that a number of power stations can be substituted by a single one that behaves equivalently to the entire set. Proceeding in this way, we obtain a variational formulation in its purest sense (without restrictions. This formulation allows us to employ the theory of calculus of variations to the highest degree. We then calculate the equivalent minimizer in the case where the cost functions are second-order polynomials. We prove that the equivalent minimizer is a second-order polynomial with piece-wise constant coefficients. Moreover, it belongs to the class C1. Finally, we present various examples prompted by real systems and perform the proposed algorithms using Mathematica.

  12. Nonlinear systems

    CERN Document Server

    Palmero, Faustino; Lemos, M; Sánchez-Rey, Bernardo; Casado-Pascual, Jesús

    2018-01-01

    This book presents an overview of the most recent advances in nonlinear science. It provides a unified view of nonlinear properties in many different systems and highlights many  new developments. While volume 1 concentrates on mathematical theory and computational techniques and challenges, which are essential for the study of nonlinear science, this second volume deals with nonlinear excitations in several fields. These excitations can be localized and transport energy and matter in the form of breathers, solitons, kinks or quodons with very different characteristics, which are discussed in the book. They can also transport electric charge, in which case they are known as polarobreathers or solectrons. Nonlinear excitations can influence function and structure in biology, as for example, protein folding. In crystals and other condensed matter, they can modify transport properties, reaction kinetics and interact with defects. There are also engineering applications in electric lattices, Josephson junction a...

  13. Posting system

    International Nuclear Information System (INIS)

    Jones, E.L.

    1983-01-01

    A posting system for the movement of equipment, such as a manipulator, into and out of an enclosure e.g. a cell or glovebox, for toxic or radioactive materials has the manipulator arranged within a collapsible bellows-like container with an end of the container cooperating with a port entry to the enclosure. The collapsible container isolates the manipulator from the environment outside the enclosure and allows the manipulator to enter and leave the contaminated enclosure without breach of the containment. A particular construction of cell for use with radioactive material is described, having a thick wall of shielding material such as concrete provided with a door normally closed by a Pb shutter and having a cylindrical gamma shield block located over the shutter on the exterior of the wall. (author)

  14. Systems engineering simplified

    CERN Document Server

    Cloutier, Robert; Bone, Mary Alice

    2015-01-01

    IntroductionOverviewDiscussion of Common TerminologyThe Case for Systems EngineeringA Brief History of Systems EngineeringSystem ExamplesSummaryThe System Life CycleManaging System Development-The Vee ModelSystem ProductionSystem Utilization and SupportSystem Retirement and DisposalOther Systems Engineering Development ModelsSpiral ModelAgile Model for Systems EngineeringSystem of InterestAbstraction and DecompositionIntegrationDeveloping and Managing RequirementsCyclone Requiremen

  15. Overview of plant life management for long term operation in nuclear power plants

    International Nuclear Information System (INIS)

    Kang, K.S.; Vincze, P.; Bychkov, A.

    2014-01-01

    Many IAEA member states have given high priority to licensing their nuclear power plants to operate for terms longer than the time frame originally anticipated (generally 40 years). The task of managing plant ageing is assigned in most member states to an engineering specialty called 'plant life management' (PLiM) applying a systematic analysis methodology to System Structure Components (SSCs) ageing. In many countries, the safety performance of nuclear power plants is periodically assessed and characterized via the periodic safety review (PSR) process. Regulatory review and acceptance of PSRs constitutes for these countries the licensing requirement for continued operation of the plant to the following PSR cycle (usually 10 years). In the USA and in other countries operating US designed plants, instead of PSR process, a license renewal application (LRA) process is followed, which requires certain prerequisites such as ageing management programs, particularly for passive irreplaceable SSCs. Active components are normally addressed via the maintenance rule (MR) requirements and other established regulatory processes. A third group of member states have adopted a combined approach that incorporates elements of both the PSR process and selected LRA specific requirements, such as time limited ageing analysis. The article ends with some IAEA recommendations for the implementation of national PLiM programs

  16. NJOY system

    International Nuclear Information System (INIS)

    Gil, Choong Sup; Kim, Jung Do

    1998-01-01

    The NJOY Nuclear Data Processing System is used to convert evaluated nuclear data in ENDF format into forms useful for applications. The NJOY code is a modular computer code designed to read evaluated data in ENDF format, transform the data in various ways, and output the results as libraries designed to be used in various applications. The modules are essentially independent programs, and they communicate with each other using input and output files, plus a very few common variables. The NJOY code can work with neutrons, photons, and charged particles. The evaluated nuclear data are reconstructed to pointwise cross sections from ENDF resonance parameters and interpolation schemes. The pointwise data can be Doppler broadened to the temperatures requested by users. The data in unresolved energy range can be computed to effective self-shielded pointwise cross sections. The cross sections and scattering matrices for free or bound scatterers in the thermal energy range are able to be produced. The self-shielded multigroup cross sections, group-to-group scattering matrices, photon-production matrices, and charged-particle cross sections from pointwise data can be generated for various application codes

  17. Chem systems

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that world styrene demand, paced by a near doubling of combined requirements in East Asia and Oceania, could reach 19.3 million metric tons by 2000, an average growth rate of 3.7%/year. So concludes Chem Systems Inc., Tarrytown, N.Y., in a study of world styrene markets through the end of the century. Pacific Rim styrene production and consumption throughout the 1990s are predicted to make up increasingly larger shares of world markets, while demand and production lag in the U.S. and western Europe. Demand and capacity in other parts of the world will grow in real terms, increasing combined market shares only slightly. Most of the increase will be driven by demand in East Asia and Oceania, where consumption by century's end is expected to increase 4.48 million metric tons from 2.25 million tons in 1991. Meantime, Japan's styrene demand in 2000 is projected at 2.64 million tons, a 500,000 ton increase from 1991 demand but a net market loss of 1.9%

  18. System safety education focused on system management

    Science.gov (United States)

    Grose, V. L.

    1971-01-01

    System safety is defined and characteristics of the system are outlined. Some of the principle characteristics include role of humans in hazard analysis, clear language for input and output, system interdependence, self containment, and parallel analysis of elements.

  19. Systems Biology and Health Systems Complexity in;

    NARCIS (Netherlands)

    Donald Combs, C.; Barham, S.R.; Sloot, P.M.A.

    2016-01-01

    Systems biology addresses interactions in biological systems at different scales of biological organization, from the molecular to the cellular, organ, organism, societal, and ecosystem levels. This chapter expands on the concept of systems biology, explores its implications for individual patients

  20. Airport Information Retrieval System (AIRS) System Design

    Science.gov (United States)

    1974-07-01

    This report presents the system design for a prototype air traffic flow control automation system developed for the FAA's Systems Command Center. The design was directed toward the immediate automation of airport data for use in traffic load predicti...

  1. THE GREEN BANK TELESCOPE 350 MHz DRIFT-SCAN SURVEY. I. SURVEY OBSERVATIONS AND THE DISCOVERY OF 13 PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Boyles, J.; Lorimer, D. R.; McLaughlin, M. A.; Cardoso, R. F. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Lynch, R. S.; Kaspi, V. M.; Archibald, A.; Karako-Argaman, C. [Department of Physics, McGill University, 3600 University St., Montreal, Quebec, H3A 2T8 (Canada); Ransom, S. M. [National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22901 (United States); Stairs, I. H.; Berndsen, A.; Cherry, A.; McPhee, C. A. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1 (Canada); Hessels, J. W. T.; Kondratiev, V. I.; Van Leeuwen, J. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Epstein, C. R. [Department of Astronomy, Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); Pennucci, T. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Roberts, M. S. E. [Eureka Scientific, 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017 (United States); Stovall, K., E-mail: jason.boyles@wku.edu [Center for Advanced Radio Astronomy and Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)

    2013-02-15

    Over the summer of 2007, we obtained 1191 hr of 'drift-scan' pulsar search observations with the Green Bank Telescope at a radio frequency of 350 MHz. Here we describe the survey setup, search procedure, and the discovery and follow-up timing of 13 pulsars. Among the new discoveries, one (PSR J1623-0841) was discovered only through its single pulses, two (PSRs J1327-0755 and J1737-0814) are millisecond pulsars, and another (PSR J2222-0137) is a mildly recycled pulsar. PSR J1327-0755 is a 2.7 ms pulsar at a dispersion measure (DM) of 27.9 pc cm{sup -3} in an 8.7 day orbit with a minimum companion mass of 0.22 M {sub Sun }. PSR J1737-0814 is a 4.2 ms pulsar at a DM of 55.3 pc cm{sup -3} in a 79.3 day orbit with a minimum companion mass of 0.06 M {sub Sun }. PSR J2222-0137 is a 32.8 ms pulsar at a very low DM of 3.27 pc cm{sup -3} in a 2.4 day orbit with a minimum companion mass of 1.11 M {sub Sun }. It is most likely a white-dwarf-neutron-star system or an unusual low-eccentricity double neutron star system. Ten other pulsars discovered in this survey are reported in the companion paper Lynch et al.

  2. The High Time Resolution Universe Pulsar Survey - XII. Galactic plane acceleration search and the discovery of 60 pulsars

    Science.gov (United States)

    Ng, C.; Champion, D. J.; Bailes, M.; Barr, E. D.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Levin, L.; Petroff, E.; Possenti, A.; Stappers, B. W.; van Straten, W.; Tiburzi, C.; Eatough, R. P.; Lyne, A. G.

    2015-07-01

    We present initial results from the low-latitude Galactic plane region of the High Time Resolution Universe pulsar survey conducted at the Parkes 64-m radio telescope. We discuss the computational challenges arising from the processing of the terabyte-sized survey data. Two new radio interference mitigation techniques are introduced, as well as a partially coherent segmented acceleration search algorithm which aims to increase our chances of discovering highly relativistic short-orbit binary systems, covering a parameter space including potential pulsar-black hole binaries. We show that under a constant acceleration approximation, a ratio of data length over orbital period of ≈0.1 results in the highest effectiveness for this search algorithm. From the 50 per cent of data processed thus far, we have redetected 435 previously known pulsars and discovered a further 60 pulsars, two of which are fast-spinning pulsars with periods less than 30 ms. PSR J1101-6424 is a millisecond pulsar whose heavy white dwarf (WD) companion and short spin period of 5.1 ms indicate a rare example of full-recycling via Case A Roche lobe overflow. PSR J1757-27 appears to be an isolated recycled pulsar with a relatively long spin period of 17 ms. In addition, PSR J1244-6359 is a mildly recycled binary system with a heavy WD companion, PSR J1755-25 has a significant orbital eccentricity of 0.09 and PSR J1759-24 is likely to be a long-orbit eclipsing binary with orbital period of the order of tens of years. Comparison of our newly discovered pulsar sample to the known population suggests that they belong to an older population. Furthermore, we demonstrate that our current pulsar detection yield is as expected from population synthesis.

  3. System specifications for the NDS Dictionary System

    International Nuclear Information System (INIS)

    Attree, P.M.; Smith, P.M.

    1979-09-01

    The NDS Dictionary System is a computerized system for maintaining and distributing the EXFOR dictionaries and for preparing internal versions of these dictionaries for use in the NDS EXFOR System and other NDS systems. This document is an internal manual for the system specifications of the NDS Dictionary System. It includes flow charts, system and program summaries, input and output specifications and file and record descriptions. This manual is updated from time to time when system modifications are made; this is the version of January 1979

  4. Quality management system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mu Sung

    2009-08-15

    This book deals with ISO9001 quality management system which includes summary of this system such as classification of quality, principle of quality management, and definition, requirement and procedure of quality management system, introduction of ISO9001 system like model of ISO9001 quality management system, ISO certificate system, structure of ISO9001 standard, requirement of ISO9001 quality management system, process approach and documentation of system, propel cases of ISO9001 quality management system.

  5. Quality management system

    International Nuclear Information System (INIS)

    Lee, Mu Sung

    2009-08-01

    This book deals with ISO9001 quality management system which includes summary of this system such as classification of quality, principle of quality management, and definition, requirement and procedure of quality management system, introduction of ISO9001 system like model of ISO9001 quality management system, ISO certificate system, structure of ISO9001 standard, requirement of ISO9001 quality management system, process approach and documentation of system, propel cases of ISO9001 quality management system.

  6. Protecting Information in Systems of Systems

    NARCIS (Netherlands)

    Trivellato, Daniel; Zannone, Nicola; Etalle, Sandro

    2011-01-01

    Systems of Systems (SoS) are dynamic, distributed coalitions of autonomous and heterogeneous systems that collaborate to achieve a common goal. While offering several advantages in terms of scalability and flexibility, the SoS paradigm has a strong impact on system interoperability and on the

  7. A security framework for systems of systems

    NARCIS (Netherlands)

    Trivellato, D.; Zannone, N.; Etalle, S.

    2011-01-01

    Systems of systems consist of a wide variety of dynamic, distributed coalitions of autonomous and heterogeneous systems that collaborate to achieve a common goal. While offering several advantages in terms of scalability and flexibility, this new paradigm has a strong impact on system

  8. A Security Framework for Systems of Systems

    NARCIS (Netherlands)

    Trivellato, Daniel; Zannone, Nicola; Etalle, Sandro

    2011-01-01

    Systems of systems consist of a wide variety of dynamic, distributed coalitions of autonomous and heterogeneous systems that collaborate to achieve a common goal. While offering several advantages in terms of scalability and flexibility, this new paradigm has a strong impact on system

  9. Systems theory of interconnected port contact systems

    NARCIS (Netherlands)

    Eberard, D.; Maschke, B.M.; Schaft, A.J. van der

    2005-01-01

    Port-based network modeling of a large class of complex physical systems leads to dynamical systems known as port-Hamiltonian systems. The key ingredient of any port-Hamiltonian system is a power-conserving interconnection structure (mathematically formalized by the geometric notion of a Dirac

  10. Digital processing data communication systems (bus systems)

    International Nuclear Information System (INIS)

    Fleck, K.

    1980-01-01

    After an introduction to the technology of digital processing data communication systems there are the following chapters: digital communication of processing data in automation technology, the technology of biserial communication, the implementaiton of a bus system, the data transmission of the TDC-2000 system of Honeywell's and the process bus CS 275 in the automation system TELEPERM M of Siemens AG. (WB) [de

  11. Networked control of microgrid system of systems

    Science.gov (United States)

    Mahmoud, Magdi S.; Rahman, Mohamed Saif Ur; AL-Sunni, Fouad M.

    2016-08-01

    The microgrid has made its mark in distributed generation and has attracted widespread research. However, microgrid is a complex system which needs to be viewed from an intelligent system of systems perspective. In this paper, a network control system of systems is designed for the islanded microgrid system consisting of three distributed generation units as three subsystems supplying a load. The controller stabilises the microgrid system in the presence of communication infractions such as packet dropouts and delays. Simulation results are included to elucidate the effectiveness of the proposed control strategy.

  12. LOFAR Discovery of the Fastest-spinning Millisecond Pulsar in the Galactic Field

    Science.gov (United States)

    Bassa, C. G.; Pleunis, Z.; Hessels, J. W. T.; Ferrara, E. C.; Breton, R. P.; Gusinskaia, N. V.; Kondratiev, V. I.; Sanidas, S.; Nieder, L.; Clark, C. J.; Li, T.; van Amesfoort, A. S.; Burnett, T. H.; Camilo, F.; Michelson, P. F.; Ransom, S. M.; Ray, P. S.; Wood, K.

    2017-09-01

    We report the discovery of PSR J0952-0607, a 707 Hz binary millisecond pulsar that is now the fastest-spinning neutron star known in the Galactic field (I.e., outside of a globular cluster). PSR J0952-0607 was found using LOFAR at a central observing frequency of 135 MHz, well below the 300 MHz to 3 GHz frequencies typically used in pulsar searches. The discovery is part of an ongoing LOFAR survey targeting unassociated Fermi-Large Area Telescope γ-ray sources. PSR J0952-0607 is in a 6.42 hr orbit around a very low-mass companion ({M}{{c}}≳ 0.02 {M}⊙ ), and we identify a strongly variable optical source, modulated at the orbital period of the pulsar, as the binary companion. The light curve of the companion varies by 1.6 mag from {r}{\\prime }=22.2 at maximum to {r}{\\prime }> 23.8, indicating that it is irradiated by the pulsar wind. Swift observations place a 3σ upper limit on the 0.3-10 {keV} X-ray luminosity of {L}Xdispersion measure). Though no eclipses of the radio pulsar are observed, the properties of the system classify it as a black widow binary. The radio pulsed spectrum of PSR J0952-0607, as determined through flux density measurements at 150 and 350 MHz, is extremely steep with α ˜ -3 (where S\\propto {ν }α ). We discuss the growing evidence that the fastest-spinning radio pulsars have exceptionally steep radio spectra, as well as the prospects for finding more sources like PSR J0952-0607.

  13. D0 Cryo System Control System Autodialer

    Energy Technology Data Exchange (ETDEWEB)

    Urbin, J.; /Fermilab

    1990-04-17

    The DO cryogenic system is controlled by a TI565-PLC based control system. This allows the system to be unmanned when in steady state operation. System experts will need to be contacted when system parameters exceed normal operating points and reach alarm setpoints. The labwide FIRUS system provides one alarm monitor and communication link. An autodialer provides a second and more flexible alarm monitor and communication link. The autodialer monitors contact points in the control system and after receiving indication of an alarm accesses a list of experts which it calls until it receives an acknowledgement. There are several manufacturers and distributors of autodialer systems. This EN explains the search process the DO cryo group used to fmd an autodialer system that fit the cryo system's needs and includes information and specs for the unit we chose.

  14. Superspeed Maglev system Transrapid. System decription

    Energy Technology Data Exchange (ETDEWEB)

    Miller, L [Thyssen Henschel AG,, Maglev Transportation Technology, Muenchen (Germany)

    1996-12-31

    The superspeed maglev system Transrapid is a track-bound transportation system for passengern and priority freight transport. The transrapid trainsets are composed of self-sufficient vehicle section coupled together. The superspeed maglev system Transrapid is capable of revenue operation at speeds of 100 to 500 km/h. Besides the description of the system concept and system characteristics safety and availability are discussed. (HW)

  15. System design specification Brayton Isotope Power System (BIPS) Flight System (FS), and Ground Demonstration System (GDS)

    International Nuclear Information System (INIS)

    1976-01-01

    The system design specification for ground demonstration, development, and flight qualification of a Brayton Isotope Power System (BIPS) is presented. The requirements for both a BIPS conceptual Flight System (FS) and a Ground Demonstration System (GDS) are defined

  16. Situation awareness with systems of systems

    CERN Document Server

    Tretmans, Jan; Borth, Michael

    2013-01-01

    This book discusses various aspects, challenges, and solutions for developing systems-of-systems for situation awareness, using applications in the domain of maritime safety and security.  Topics include advanced, multi-objective visualization methods for situation awareness, stochastic outlier selection, rule-based anomaly detection, an ontology-based event model for semantic reasoning, new methods for semi-automatic generation of adapters bridging communication gaps, security policies for systems-of-systems, trust assessment, and methods to deal with the dynamics of systems-of-systems in run-time monitoring, testing, and diagnosis. Architectural considerations for designing information-centric systems-of-systems such as situation awareness systems, and an integrated demonstrator implementing many of the investigated aspects, complete the book.

  17. System specifications for the NDS EXFOR System

    International Nuclear Information System (INIS)

    Attree, P.M.; Smith, P.M.

    1979-07-01

    EXFOR is the agreed exchange format for the magnetic-tape exchange of nuclear reaction data between national and international nuclear data centres for the benefit of nuclear data users in all countries. The NDS EXFOR System is a computerized system for the storage and retrieval of EXFOR information compiled or received by the IAEA. This document is an internal manual for the system specifications of the NDS EXFOR System. It includes flow charts, system and program summaries, input and output specifications and file and record descriptions. The manual is updated from time to time when system modifications are made

  18. System specifications for the NDS EXFOR System

    Energy Technology Data Exchange (ETDEWEB)

    Attree, P M; Smith, P M

    1982-06-01

    EXFOR is the agreed exchange format for the magnetic-tape exchange of nuclear reaction data between national and international nuclear data centers for the benefit of nuclear data users in all countries. The NDS EXFOR System is a computerized system for the storage and retrieval of EXFOR information compiled or received of the IAEA. This document is an internal manual for the system specifications of the NDS EXFOR System. It includes flow charts, system and program summaries, input and output specifications and file and record descriptions. The manual is updated from time to time when system modifications are made; the first version was issued in July 1979. (author)

  19. Computer System Design System-on-Chip

    CERN Document Server

    Flynn, Michael J

    2011-01-01

    The next generation of computer system designers will be less concerned about details of processors and memories, and more concerned about the elements of a system tailored to particular applications. These designers will have a fundamental knowledge of processors and other elements in the system, but the success of their design will depend on the skills in making system-level tradeoffs that optimize the cost, performance and other attributes to meet application requirements. This book provides a new treatment of computer system design, particularly for System-on-Chip (SOC), which addresses th

  20. Smart electromechanical systems the central nervous system

    CERN Document Server

    Kurbanov, Vugar

    2017-01-01

    This book describes approaches to solving the problems of developing the central nervous system of robots (CNSR) based on smart electromechanical systems (SEMS) modules, principles of construction of the various modules of the central nervous system and variants of mathematical software CNSR in control systems for intelligent robots. It presents the latest advances in theory and practice at the Russian Academy of Sciences. Developers of intelligent robots to solve modern problems in robotics are increasingly addressing the use of the bionic approach to create robots that mimic the complexity and adaptability of biological systems. These have smart electromechanical system (SEMS), which are used in various cyber-physical systems (CPhS), and allow the functions of calculation, control, communications, information storage, monitoring, measurement and control of parameters and environmental parameters to be integrated. The behavior of such systems is based on the information received from the central nervous syst...

  1. Multiobjective Collaborative Optimization of Systems of Systems

    National Research Council Canada - National Science Library

    Wolf, Robert A

    2005-01-01

    ...; in other words an inefficient design of the system of systems. This thesis examines the simultaneous design of several ships using the sea base concept as an example application of a network of ships working together...

  2. Situation Awareness with Systems of Systems

    NARCIS (Netherlands)

    Laar, P. van de; Tretmans, J.; Borth, M.

    2013-01-01

    This book discusses various aspects, challenges, and solutions for developing systems-of-systems for situation awareness, using applications in the domain of maritime safety and security. Topics include advanced, multi-objective visualization methods for situation awareness, stochastic outlier

  3. Linking Political Systems and War Systems

    DEFF Research Database (Denmark)

    Harste, Gorm

    2009-01-01

    Decisive parts of the Western political system have demonstrated a seemingly surprising misinterpretation of military might. As Madelaine Albright has suggested, the mighty perceived themselves as "almighty". Political power seems to have invested in instrumental coercive power relations and found...... military coercion to be the appropriate mean. Using the system theory and the theory of systemic risks displayed by the German sociologist Niklas Luhmann the article demonstrates how military systems due to their own autonomy and autopoiesis do not fit into the idea of political government....... The Clausewitzian ideal of a political system that could continue its power games by means of war was moderated by Clausewitz' own analysis of "friction". How can a political system be so blind towards the possibilities of another system? What are the risks of systemic blind spots? The argument of the paper...

  4. Designing information systems

    CERN Document Server

    Blethyn, Stanley G

    2014-01-01

    Designing Information Systems focuses on the processes, methodologies, and approaches involved in designing information systems. The book first describes systems, management and control, and how to design information systems. Discussions focus on documents produced from the functional construction function, users, operators, analysts, programmers and others, process management and control, levels of management, open systems, design of management information systems, and business system description, partitioning, and leveling. The text then takes a look at functional specification and functiona

  5. Cognitive Medical Multiagent Systems

    OpenAIRE

    Barna Iantovics

    2010-01-01

    The development of efficient and flexible agent-based medical diagnosis systems represents a recent research direction. Medical multiagent systems may improve the efficiency of traditionally developed medical computational systems, like the medical expert systems. In our previous researches, a novel cooperative medical diagnosis multiagent system called CMDS (Contract Net Based Medical Diagnosis System) was proposed. CMDS system can solve flexibly a large variety of medical diagnosis problems...

  6. Non linear system become linear system

    Directory of Open Access Journals (Sweden)

    Petre Bucur

    2007-01-01

    Full Text Available The present paper refers to the theory and the practice of the systems regarding non-linear systems and their applications. We aimed the integration of these systems to elaborate their response as well as to highlight some outstanding features.

  7. System Design of the SWRL Financial System.

    Science.gov (United States)

    Ikeda, Masumi

    To produce various management and accounting reports in order to maintain control of SWRL (Southwest Regional Laboratory) operational and financial activities, a computer-based SWRL financial system was developed. The system design is outlined, and various types of system inputs described. The kinds of management and accounting reports generated…

  8. Triggering system innovation in agricultural innovation systems

    NARCIS (Netherlands)

    Turner, James A.; Williams, Tracy; Nicholas, Graeme; Foote, Jeff; Rijswijk, Kelly; Barnard, Tim; Beechener, Sam; Horita, Akiko

    2017-01-01

    This article describes a process for stimulating engagement among change agents to develop a shared understanding of systemic problems in the agricultural innovation system (AIS), challenge prevalent institutional logics and identify actions they might undertake to stimulate system innovation.

  9. Port contact systems for irreversible thermodynamical systems

    NARCIS (Netherlands)

    Eberard, D.; Maschke, B.M.; Schaft, A.J. van der

    2005-01-01

    In this paper we propose a definition of control contact systems, generalizing input-output Hamiltonian systems, to cope with models arising from irreversible Thermodynamics. We exhibit a particular subclass of these systems, called conservative, that leaves invariant some Legendre submanifold (the

  10. Modeling learning technology systems as business systems

    NARCIS (Netherlands)

    Avgeriou, Paris; Retalis, Symeon; Papaspyrou, Nikolaos

    2003-01-01

    The design of Learning Technology Systems, and the Software Systems that support them, is largely conducted on an intuitive, ad hoc basis, thus resulting in inefficient systems that defectively support the learning process. There is now justifiable, increasing effort in formalizing the engineering

  11. General Systems Theory and Instructional Systems Design.

    Science.gov (United States)

    Salisbury, David F.

    1990-01-01

    Describes basic concepts in the field of general systems theory (GST) and identifies commonalities that exist between GST and instructional systems design (ISD). Models and diagrams that depict system elements in ISD are presented, and two matrices that show how GST has been used in ISD literature are included. (11 references) (LRW)

  12. Expert systems in process control systems

    International Nuclear Information System (INIS)

    Wittig, T.

    1987-01-01

    To illustrate where the fundamental difference between expert systems in classical diagnosis and in industrial control lie, the work of process control instrumentation is used as an example for the job of expert systems. Starting from the general process of problem-solving, two classes of expert systems can be defined accordingly. (orig.) [de

  13. Expert Systems for auditing management information systems

    Directory of Open Access Journals (Sweden)

    Gheroghe Popescu

    2007-05-01

    Full Text Available Expert systems are built with the help of: specialised programming languages or expert system generators (shell. But this structure was reached after tens of years of work and research, because expert systems are nothing but pragmatic capitalisation of the results of research carried out in artificial intelligence and theory of knowledge.

  14. Psychology of system design

    CERN Document Server

    Meister, D

    2014-01-01

    This is a book about systems, including: systems in which humans control machines; systems in which humans interact with humans and the machine component is relatively unimportant; systems which are heavily computerized and those that are not; and governmental, industrial, military and social systems. The book deals with both traditional systems like farming, fishing and the military, and with systems just now tentatively emerging, like the expert and the interactive computer system. The emphasis is on the system concept and its implications for analysis, design and evaluation of these many di

  15. Biomedical signals and systems

    CERN Document Server

    Tranquillo, Joseph V

    2013-01-01

    Biomedical Signals and Systems is meant to accompany a one-semester undergraduate signals and systems course. It may also serve as a quick-start for graduate students or faculty interested in how signals and systems techniques can be applied to living systems. The biological nature of the examples allows for systems thinking to be applied to electrical, mechanical, fluid, chemical, thermal and even optical systems. Each chapter focuses on a topic from classic signals and systems theory: System block diagrams, mathematical models, transforms, stability, feedback, system response, control, time

  16. Operating System Security

    CERN Document Server

    Jaeger, Trent

    2008-01-01

    Operating systems provide the fundamental mechanisms for securing computer processing. Since the 1960s, operating systems designers have explored how to build "secure" operating systems - operating systems whose mechanisms protect the system against a motivated adversary. Recently, the importance of ensuring such security has become a mainstream issue for all operating systems. In this book, we examine past research that outlines the requirements for a secure operating system and research that implements example systems that aim for such requirements. For system designs that aimed to

  17. Systems Measures of Water Distribution System Resilience

    Energy Technology Data Exchange (ETDEWEB)

    Klise, Katherine A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Murray, Regan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Walker, La Tonya Nicole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    Resilience is a concept that is being used increasingly to refer to the capacity of infrastructure systems to be prepared for and able to respond effectively and rapidly to hazardous events. In Section 2 of this report, drinking water hazards, resilience literature, and available resilience tools are presented. Broader definitions, attributes and methods for measuring resilience are presented in Section 3. In Section 4, quantitative systems performance measures for water distribution systems are presented. Finally, in Section 5, the performance measures and their relevance to measuring the resilience of water systems to hazards is discussed along with needed improvements to water distribution system modeling tools.

  18. Manager's assistant systems for space system planning

    Science.gov (United States)

    Bewley, William L.; Burnard, Robert; Edwards, Gary E.; Shoop, James

    1992-01-01

    This paper describes a class of knowledge-based 'assistant' systems for space system planning. Derived from technology produced for the DARPA/USAF Pilot's Associate program, these assistant systems help the human planner by doing the bookkeeping to maintain plan data and executing the procedures and heuristics currently used by the human planner to define, assess, diagnose, and revise plans. Intelligent systems for Space Station Freedom assembly sequence planning and Advanced Launch System modeling will be presented as examples. Ongoing NASA-funded work on a framework supporting the development of such tools will also be described.

  19. Lighting system with thermal management system

    Science.gov (United States)

    Arik, Mehmet; Weaver, Stanton; Stecher, Thomas; Seeley, Charles; Kuenzler, Glenn; Wolfe, Jr., Charles; Utturkar, Yogen; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2013-05-07

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  20. Development of procedural requirements for life extension of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hun; Son, Moon Kyu [Korea Association for Nuclear Technology, Taejon (Korea, Republic of); Ham, Cheol Hun [The Catholic University of Korea, Seoul (Korea, Republic of); Chang, Keun Sun [Sunmoon Univ., Asan (Korea, Republic of); Paek, Won Phil [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Cheong, Ji Hwan [Baekseok College Cultural Studies, Cheonan (Korea, Republic of)

    2001-03-15

    Current status of regulatory aspects of life extension and upgrading of NPPs is reviewed for major foreign countries. Most countries require similar technical requirements; however, procedural aspects differ country by country. Regulatory systems suitable for NPP life extension is investigated. The procedure and requirements for reassessment of design life should be established first; then it can be incorporated into the PSR system. The concept of 'Current Licensing Basis (CLB)' can be adopted in Korea, but further elaboration for terms and definitions is needed for common understanding between interested groups. The procedure for maintenance and backfitting should also be improved. The Systems, Structures, and Components (SSCs) that require development of regulatory requirements for life extension are identified based on extensive analysis of foreign experiences. By analyzing the rules and regulations related to life extension. Basic directions are suggested to harmonize or establish regulatory systems for life extension, two-step licensing, PSR, and backfitting.

  1. EPICS based DAQ system

    International Nuclear Information System (INIS)

    Cheng Weixing; Chen Yongzhong; Zhou Weimin; Ye Kairong; Liu Dekang

    2002-01-01

    EPICS is the most popular developing platform to build control system and beam diagnostic system in modern physics experiment facilities. An EPICS based data acquisition system was built in Redhat 6.2 operation system. The system is successfully used in the beam position monitor mapping, it improves the mapping process a lot

  2. Autonomous photovoltaic lighting system

    OpenAIRE

    Hafez, Ahmed A. A.; Montesinos Miracle, Daniel; Sudrià Andreu, Antoni

    2012-01-01

    This paper introduces a comparison between the conventional and Photovoltaic (PV) lighting systems. A simple sizing procedure for a PV stand-alone system was advised. The paper also proposes a novel PV lighting system. The proposed system is simple, compact and reliable. The system operation was investigated by thoroughly mathematical and simulation work.

  3. FFTF control system experience

    International Nuclear Information System (INIS)

    Warrick, R.P.

    1981-01-01

    The FFTF control systems provide control equipment for safe and efficient operation of the plant. For convenience, these systems will be divided into three parts for discussions: (1) Plant Protection System (PPS); (2) Plant Control System (PCS); and (3) General Observations. Performance of each of these systems is discussed

  4. Automatic control systems engineering

    International Nuclear Information System (INIS)

    Shin, Yun Gi

    2004-01-01

    This book gives descriptions of automatic control for electrical electronics, which indicates history of automatic control, Laplace transform, block diagram and signal flow diagram, electrometer, linearization of system, space of situation, state space analysis of electric system, sensor, hydro controlling system, stability, time response of linear dynamic system, conception of root locus, procedure to draw root locus, frequency response, and design of control system.

  5. MEA vacuum system

    International Nuclear Information System (INIS)

    Stroo, R.; Schwebke, H.; Heine, E.

    1984-01-01

    This report describes construction and operation of the MEA vacuum system of NIKHEF (Netherlands). First, the klystron vacuum system, beam transport system, diode pump and a triode pump are described. Next, the isolation valve and the fast valves of the vacuum system are considered. Measuring instruments, vacuum system commands and messages of failures are treated in the last chapter. (G.J.P.)

  6. From systems biology to systems biomedicine.

    Science.gov (United States)

    Antony, Paul M A; Balling, Rudi; Vlassis, Nikos

    2012-08-01

    Systems Biology is about combining theory, technology, and targeted experiments in a way that drives not only data accumulation but knowledge as well. The challenge in Systems Biomedicine is to furthermore translate mechanistic insights in biological systems to clinical application, with the central aim of improving patients' quality of life. The challenge is to find theoretically well-chosen models for the contextually correct and intelligible representation of multi-scale biological systems. In this review, we discuss the current state of Systems Biology, highlight the emergence of Systems Biomedicine, and highlight some of the topics and views that we think are important for the efficient application of Systems Theory in Biomedicine. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Mapping biological systems to network systems

    CERN Document Server

    Rathore, Heena

    2016-01-01

    The book presents the challenges inherent in the paradigm shift of network systems from static to highly dynamic distributed systems – it proposes solutions that the symbiotic nature of biological systems can provide into altering networking systems to adapt to these changes. The author discuss how biological systems – which have the inherent capabilities of evolving, self-organizing, self-repairing and flourishing with time – are inspiring researchers to take opportunities from the biology domain and map them with the problems faced in network domain. The book revolves around the central idea of bio-inspired systems -- it begins by exploring why biology and computer network research are such a natural match. This is followed by presenting a broad overview of biologically inspired research in network systems -- it is classified by the biological field that inspired each topic and by the area of networking in which that topic lies. Each case elucidates how biological concepts have been most successfully ...

  8. Environmental Management System

    Science.gov (United States)

    Goals Recycling Green Purchasing Pollution Prevention Reusing Water Resources Environmental Management Stewardship » Environmental Protection » Environmental Management System Environmental Management System An Environmental Management System is a systematic method for assessing mission activities, determining the

  9. System floorplanning optimization

    KAUST Repository

    Browning, David W.; Elansary, Ayman; Shalaby, Mohamed

    2012-01-01

    Notebook and Laptop Original Equipment Manufacturers (OEMs) place great emphasis on creating unique system designs to differentiate themselves in the mobile market. These systems are developed from the 'outside in' with the focus on how the system

  10. Connected motorcycle system performance.

    Science.gov (United States)

    2016-01-15

    This project characterized the performance of Connected Vehicle Systems (CVS) on motorcycles based on two key components: global positioning and wireless communication systems. Considering that Global Positioning System (GPS) and 5.9 GHz Dedicated Sh...

  11. Antiskid braking system

    Science.gov (United States)

    Pazdera, J. S.

    1974-01-01

    Published report describes analytical development and simulation of braking system. System prevents wheels from skidding when brakes are applied, significantly reducing stopping distance. Report also presents computer simulation study on system as applied to aircraft.

  12. Bridge Management Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way....

  13. TWRSview system requirements specification

    International Nuclear Information System (INIS)

    Caldwell, J.A.; Lee, A.K.

    1995-12-01

    This document provides the system requirements specification for the TWRSview software system. The TWRSview software system is being developed to integrate electronic data supporting the development of the TWRS technical baseline

  14. Calo trigger acquisition system

    CERN Multimedia

    Franchini, Matteo

    2016-01-01

    Calo trigger acquisition system - Evolution of the acquisition system from a multiple boards system (upper, orange cables) to a single board one (below, light blue cables) where all the channels are collected in a single board.

  15. Lungs and Respiratory System

    Science.gov (United States)

    ... Videos for Educators Search English Español Lungs and Respiratory System KidsHealth / For Parents / Lungs and Respiratory System ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't ...

  16. The Trinity System

    Energy Technology Data Exchange (ETDEWEB)

    Archer, Billy Joe [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vigil, Benny Manuel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-13

    This paper describes the Trinity system, the first ASC Advanced Technology System (ATS-1). We describe the Trinity procurement timeline, the ASC computing strategy, the Trinity specific mission needs, and the Trinity system specifications.

  17. Pneumatic transfer systems

    International Nuclear Information System (INIS)

    Bichler, H.; Boeck, H.; Hammer, J.; Buchtela, K.

    1988-11-01

    A pneumatic transfer system for research reactors, including a sample changer system and to be used for neutron activation analysis, is described. The system can be obtained commercially from the Atominstitut. 2 figs. (qui)

  18. Immune System Quiz

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Quiz: Immune System KidsHealth / For Kids / Quiz: Immune System Print How much do you know about your immune system? Find out by taking this quiz! About Us ...

  19. System floorplanning optimization

    KAUST Repository

    Browning, David W.; Ansary, Ayman M. El; Shalaby, Mohamed

    2013-01-01

    Notebook and Laptop Original Equipment Manufacturers (OEMs) place great emphasis on creating unique system designs to differentiate themselves in the mobile market. These systems are developed from the 'outside in' with the focus on how the system

  20. Autonomic Nervous System Disorders

    Science.gov (United States)

    Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart ... breathing and swallowing Erectile dysfunction in men Autonomic nervous system disorders can occur alone or as the result ...

  1. Central Nervous System Vasculitis

    Science.gov (United States)

    ... of Vasculitis / Central Nervous System (CNS) Vasculitis Central Nervous System (CNS) Vasculitis Swap out your current Facebook Profile ... Facebook personal page. Replace with this image. Central nervous system (CNS) vasculitis is inflammation of blood vessel walls ...

  2. Wind energy systems

    Science.gov (United States)

    Stewart, H. J.

    1978-01-01

    A discussion on wind energy systems involved with the DOE wind energy program is presented. Some of the problems associated with wind energy systems are discussed. The cost, efficiency, and structural design of wind energy systems are analyzed.

  3. System Software 7 Macintosh

    CERN Multimedia

    1991-01-01

    System 7 is a single-user graphical user interface-based operating system for Macintosh computers and was part of the classic Mac OS line of operating systems. It was introduced on May 13, 1991, by Apple Computer. It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997. Features added with the System 7 release included virtual memory, personal file sharing, QuickTime, QuickDraw 3D, and an improved user interface. This is the first real major evolution of the Macintosh system, bringing a significant improvement in the user interface, improved stability and many new features such as the ability to use multiple applications at the same time. "System 7" is the last operating system name of the Macintosh that contains the word "system". Macintosh operating systems were later called "Mac OS" (for Macintosh Operating System).

  4. Marketing reporting system

    OpenAIRE

    Hanić Hasan M.

    2004-01-01

    The main components of a developed and good organized marketing information system are: internal reporting system, marketing reporting system, market research system and analytical marketing system. Marketing reporting system provides data and information about changes in business and micro marketing environment. This component of MIS ensures that marketing managers are up-to-date with what is going on, and to be informed about changes in company marketing environment.

  5. Marketing reporting system

    Directory of Open Access Journals (Sweden)

    Hanić Hasan M.

    2004-01-01

    Full Text Available The main components of a developed and good organized marketing information system are: internal reporting system, marketing reporting system, market research system and analytical marketing system. Marketing reporting system provides data and information about changes in business and micro marketing environment. This component of MIS ensures that marketing managers are up-to-date with what is going on, and to be informed about changes in company marketing environment.

  6. Propulsion Systems Panel deliberations

    Science.gov (United States)

    Bianca, Carmelo J.; Miner, Robert; Johnston, Lawrence M.; Bruce, R.; Dennies, Daniel P.; Dickenson, W.; Dreshfield, Robert; Karakulko, Walt; Mcgaw, Mike; Munafo, Paul M.

    1993-01-01

    The Propulsion Systems Panel was established because of the specialized nature of many of the materials and structures technology issues related to propulsion systems. This panel was co-chaired by Carmelo Bianca, MSFC, and Bob Miner, LeRC. Because of the diverse range of missions anticipated for the Space Transportation program, three distinct propulsion system types were identified in the workshop planning process: liquid propulsion systems, solid propulsion systems and nuclear electric/nuclear thermal propulsion systems.

  7. Small test SDHW systems

    DEFF Research Database (Denmark)

    Vejen, Niels Kristian

    1999-01-01

    Three small test SDHW systems was tested in a laboratory test facility.The three SDHW systems where all based on the low flow principe and a mantle tank but the design of the systems where different.......Three small test SDHW systems was tested in a laboratory test facility.The three SDHW systems where all based on the low flow principe and a mantle tank but the design of the systems where different....

  8. Battery systems engineering

    CERN Document Server

    Rahn, Christopher D

    2012-01-01

    A complete all-in-one reference on the important interdisciplinary topic of Battery Systems Engineering Focusing on the interdisciplinary area of battery systems engineering, this book provides the background, models, solution techniques, and systems theory that are necessary for the development of advanced battery management systems. It covers the topic from the perspective of basic electrochemistry as well as systems engineering topics and provides a basis for battery modeling for system engineering of electric and hybrid electric vehicle platforms. This original

  9. Gas transfer system

    International Nuclear Information System (INIS)

    Oberlin, J.C.; Frick, G.; Kempfer, C.; North, C.

    1988-09-01

    The state of work on the Vivitron gas transfer system and the system functions are summarized. The system has to: evacuate the Vivitron reservoir; transfer gas from storage tanks to the Vivitron; recirculate gas during operation; transfer gas from the Vivitron to storage tanks; and assure air input. The system is now being installed. Leak alarms are given by SF6 detectors, which set off a system of forced ventilation. Another system continuously monitors the amount of SF6 in the tanks [fr

  10. Cognitive Medical Multiagent Systems

    Directory of Open Access Journals (Sweden)

    Barna Iantovics

    2010-01-01

    Full Text Available The development of efficient and flexible agent-based medical diagnosis systems represents a recent research direction. Medical multiagent systems may improve the efficiency of traditionally developed medical computational systems, like the medical expert systems. In our previous researches, a novel cooperative medical diagnosis multiagent system called CMDS (Contract Net Based Medical Diagnosis System was proposed. CMDS system can solve flexibly a large variety of medical diagnosis problems. This paper analyses the increased intelligence of the CMDS system, which motivates its use for different medical problem’s solving.

  11. Airports Geographic Information System -

    Data.gov (United States)

    Department of Transportation — The Airports Geographic Information System maintains the airport and aeronautical data required to meet the demands of the Next Generation National Airspace System....

  12. Aeronautical Information System -

    Data.gov (United States)

    Department of Transportation — The Aeronautical Information System (AIS) is a leased weather automated system that provides a means of collecting and distributing aeronautical weather information...

  13. Credit Management System

    Data.gov (United States)

    US Agency for International Development — Credit Management System. Outsourced Internet-based application. CMS stores and processes data related to USAID credit programs. The system provides information...

  14. Control system design method

    Science.gov (United States)

    Wilson, David G [Tijeras, NM; Robinett, III, Rush D.

    2012-02-21

    A control system design method and concomitant control system comprising representing a physical apparatus to be controlled as a Hamiltonian system, determining elements of the Hamiltonian system representation which are power generators, power dissipators, and power storage devices, analyzing stability and performance of the Hamiltonian system based on the results of the determining step and determining necessary and sufficient conditions for stability of the Hamiltonian system, creating a stable control system based on the results of the analyzing step, and employing the resulting control system to control the physical apparatus.

  15. Neural Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  16. Integrated Systems Health Management for Intelligent Systems

    Science.gov (United States)

    Figueroa, Fernando; Melcher, Kevin

    2011-01-01

    The implementation of an integrated system health management (ISHM) capability is fundamentally linked to the management of data, information, and knowledge (DIaK) with the purposeful objective of determining the health of a system. It is akin to having a team of experts who are all individually and collectively observing and analyzing a complex system, and communicating effectively with each other in order to arrive at an accurate and reliable assessment of its health. In this paper, concepts, procedures, and approaches are presented as a foundation for implementing an intelligent systems ]relevant ISHM capability. The capability stresses integration of DIaK from all elements of a system. Both ground-based (remote) and on-board ISHM capabilities are compared and contrasted. The information presented is the result of many years of research, development, and maturation of technologies, and of prototype implementations in operational systems.

  17. System Analysis and Risk Assessment (SARA) system

    International Nuclear Information System (INIS)

    Krantz, E.A.; Russell, K.D.; Stewart, H.D.; Van Siclen, V.S.

    1986-01-01

    Utilization of Probabilistic Risk Assessment (PRA) related information in the day-to-day operation of plant systems has, in the past, been impracticable due to the size of the computers needed to run PRA codes. This paper discusses a microcomputer-based database system which can greatly enhance the capability of operators or regulators to incorporate PRA methodologies into their routine decision making. This system is called the System Analysis and Risk Assessment (SARA) system. SARA was developed by EG and G Idaho, Inc. at the Idaho National Engineering Laboratory to facilitate the study of frequency and consequence analyses of accident sequences from a large number of light water reactors (LWRs) in this country. This information is being amassed by several studies sponsored by the United States Nuclear Regulatory Commission (USNRC). To meet the need of portability and accessibility, and to perform the variety of calculations necessary, it was felt that a microcomputer-based system would be most suitable

  18. Systems engineering for very large systems

    Science.gov (United States)

    Lewkowicz, Paul E.

    Very large integrated systems have always posed special problems for engineers. Whether they are power generation systems, computer networks or space vehicles, whenever there are multiple interfaces, complex technologies or just demanding customers, the challenges are unique. 'Systems engineering' has evolved as a discipline in order to meet these challenges by providing a structured, top-down design and development methodology for the engineer. This paper attempts to define the general class of problems requiring the complete systems engineering treatment and to show how systems engineering can be utilized to improve customer satisfaction and profit ability. Specifically, this work will focus on a design methodology for the largest of systems, not necessarily in terms of physical size, but in terms of complexity and interconnectivity.

  19. Epilogue: Systems Approaches and Systems Practice

    Science.gov (United States)

    Reynolds, Martin; Holwell, Sue

    Each of the five systems approaches discussed in this volume: system dynamics (SD), the viable systems model (VSM), strategic options development and analysis (SODA), soft systems methodology (SSM) and critical systems heuristics (CSH) has a pedigree. Not in the sense of the sometimes absurd spectacle of animals paraded at dog shows. Rather, their pedigree derives from their systems foundations, their capacity to evolve and their flexibility in use. None of the five approaches has developed out of use in restricted and controlled contexts of either low or high levels of complicatedness. Neither has any one of them evolved as a consequence of being applied only to situations with either presumed stakeholder agreement on purpose, or courteous disagreement amongst stakeholders, or stakeholder coercion. The compilation is not a celebration of abstract ‘methodologies', but of theoretically robust approaches that have a genuine pedigree in practice.

  20. Systems analysis of a security alarm system

    International Nuclear Information System (INIS)

    Schiff, A.

    1975-01-01

    When the Lawrence Livermore Laboratory found that its security alarm system was causing more false alarms and maintenance costs than LLL felt was tolerable, a systems analysis was undertaken to determine what should be done about the situation. This report contains an analysis of security alarm systems in general and ends with a review of the existing Security Alarm Control Console (SACC) and recommendations for its improvement, growth and change. (U.S.)