WorldWideScience

Sample records for psr pacific-sierra research

  1. 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

  2. Nuclear Weapon Effect Research at PSR (Pacific-Sierra Research Corporation) - 1983. Symptomatology of Acute Radiation Effects in Humans after Exposure to Doses of 75 to 4500 Rads (cGy) Free-in-Air

    Science.gov (United States)

    1984-08-31

    David L. Auton and Cyrus P. Knowles supervised the research, and the IDP Core Group provided advisory support. Related reports include: George H. Anno...Cruiser-Destroyer Group 8 ATTN: Dir of Libraries I ATTN: Commander USA Military Academy David Taylor Naval Ship R&D Ctr ATTN: Doc Library ATTN.: Code... Shrier ATTN: V. Jackson 2 cys ATTN: Security & Subnation Conflict Horizons Technology, Inc ATTN: J. Palmer Rand CorpATTN: B. Bennett lIT Research

  3. 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

  4. 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)

  5. 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.).

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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...

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.)

  2. 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.

  3. 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

  4. 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.

  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. 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.

  7. 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

  8. 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

  9. 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

  10. 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).

  11. 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.

  12. Current Status of Periodic Safety Review of HANARO Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Minjin; Ahn, Guk-Hoon; Lee, Choong Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    A PSR for a research reactor became a legal requirement as the Nuclear Safety Act was amended and came into effect in 2014. This paper describes the current status and methodology of the first Periodic Safety Review (PSR) of HANARO that is being performed. The legal requirements, work plan, and process of implementing a PSR are described. Because this is the first PSR for a research reactor, it is our understating that the operating organization and regulatory body should communicate well with each other to complete the PSR in a timely manner. The first PSR of HANARO is under way. In order to achieve a successful result, activities of the operation organization such as scheduling, maintaining consistency in input data for review, and reviewing the PSR reports that will require intensive resources should be well planned. This means the operating organization needs to incorporate appropriate measures to ensure the transfer of knowledge and expertise arising from the PSR via a contractor to the operation organization. It is desirable for the Regulatory Body to be involved in all stage of the PSR to prevent any waste of resources and minimize the potential for a reworking of the PSR and the need for an additional assessment and review as recommended by foreign experts.

  13. 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

  14. 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, ...

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  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. 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)

  14. 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

  15. 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

  16. 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 ...

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  16. 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

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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 ...

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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%.

  3. 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.

  4. 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.

  5. 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

  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. 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)

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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) ...

  6. 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.

  7. 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....

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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).

  9. 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

  10. 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.

  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. 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.

  13. 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.

  14. 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 $L_x/\\dot{E}\\sim 0.5-5 \\times 10^{-3} (d/0.23 {kpc})^2$.

  15. 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.

  16. 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.

  17. 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.)

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  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. 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.

  17. Research

    African Journals Online (AJOL)

    ebutamanya

    2015-03-02

    Mar 2, 2015 ... Joseph Daniels1,&, Ruth Nduati1,2, James Kiarie1,3, Carey Farquhar1,4,5 .... or basic science research career (Socio-Behavioral Research, .... a research environment that supports knowledge sharing to develop research ...

  18. Research

    African Journals Online (AJOL)

    A descriptive qualitative research design was used to determine whether participants ... simulation as a teaching method; a manikin offering effective learning; confidence ..... Tesch R. Qualitative Research: Analysis Types and Software Tools.

  19. Research

    African Journals Online (AJOL)

    research process, as part of which students must find and appraise evidence from research.[5] This highlights that teaching research methodology is inclined towards equipping students ... Students believed that evidence-based practice was vital, yet their understanding of the concept was restricted when compared with the.

  20. Research

    African Journals Online (AJOL)

    2014-05-06

    May 6, 2014 ... facilitate and support articulation between the ECT mid-level worker qualification and the professional B EMC degree. Methods. The researchers used an exploratory, sequential mixed-method design, which is characterised by a qualitative phase of research followed by a quantitative phase. This design is ...

  1. Research

    African Journals Online (AJOL)

    supports medical education and research at institutions in 12 ... (CBE). CapacityPlus, led by IntraHealth International, is the USAID-funded ... acquire public health, clinical, and/or research skills, usually through applied learning in a .... If students were evaluated, indicate the type of student (i.e. medical, dental, nursing, etc.) ...

  2. Research

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    abp

    2017-01-24

    Jan 24, 2017 ... and the specific rotavirus VP4 (P-types) and VP7 (G-types) determined. Results: The .... Centre for Virus Research (CVR) of the Kenya Medical Research. Institute (KEMRI) ... rotavirus dsRNA was run on 10% polyacrylamide resolving gels using a large format .... What is known about this topic. •. Rotavirus is ...

  3. Research

    African Journals Online (AJOL)

    abp

    2017-10-25

    Oct 25, 2017 ... stigma and superstition are known to lead to frequent presentation .... The limited documented research on challenges to help-seeking behaviour for cancer ..... to touch your breast [16] that breast self-examination may cause.

  4. Research

    African Journals Online (AJOL)

    ebutamanya

    2015-10-02

    Oct 2, 2015 ... thought to prevent infection, but recent research has proven otherwise. In addition ... One patient had ophthalmalgia and was exposed to. Kaiy for one year and ... migraine, ear infections, tuberculosis, bone fractures, epilepsy,.

  5. Research

    African Journals Online (AJOL)

    abp

    2016-07-12

    Jul 12, 2016 ... multiple risk factors provides support for multiple-behavior interventions as ... consumption) with smoking therefore needs further research. As such this study .... restaurants, in bars, and on a statewide basis. They preferred to.

  6. Research

    African Journals Online (AJOL)

    The mini-clinical-evaluation exercise (mini-CEX) is a way of assessing the clinical ... Ethical approval for this study was obtained from the Medical Health. Research ..... mini-CEX assessment and feedback session, the greater the likelihood of.

  7. Research

    African Journals Online (AJOL)

    abp

    2016-04-14

    Apr 14, 2016 ... Qualitative data, content analysis approach was used. Results: Overall 422 .... Study design: A mixed method cross-sectional design using both quantitative and qualitative research methods as described by. Hanson et al [33] ...

  8. Research

    International Nuclear Information System (INIS)

    1999-01-01

    Subjects covered in this section are: (1) PCAST panel promotes energy research cooperation; (2) Letter issued by ANS urges funding balance in FFTF restart consideration and (3) FESAC panel releases report on priorities and balance

  9. Research

    African Journals Online (AJOL)

    Research. December 2017, Vol. 9, No. 4 AJHPE 171. During curriculum development, teachers ... Ideally, examiners need an educational method to determine ..... A major focus of this study was addressing the human resource gap when.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Research

    African Journals Online (AJOL)

    abp

    2017-05-18

    May 18, 2017 ... available to populations of developing countries [2-5]. In 2013, in. Western and Central Europe and ..... initiation among the infected persons in the community. Addressing stigma and educating ... Lifespan/Tufts/Brown Center for AIDS Research (P30AI042853). Tables. Table 1: Baseline characteristics of ...

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    African Journals Online (AJOL)

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    15 févr. 2016 ... présentent un Indice de Masse Corporel (IMC) normal, les autres femmes sont soit ..... In The health belief model and personal health behavior, edited by MH ... Evaluation of the Osteoporosis Health Belief Scale. Research in.

  5. Research

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    2017-03-14

    Mar 14, 2017 ... R Ebrahim,1 MSc (Dent); H Julie,2 MPH, MCur, PhD. 1 Extended ... and research is applied to develop and sustain society.[5]. Methods .... service they want, not the service we want to give whether they want it or. Co math. G.

  6. Research

    African Journals Online (AJOL)

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    2017-11-24

    Nov 24, 2017 ... Page number not for citation purposes. 1. Prevalence and determinants of common mental ..... illnesses were smoke cigarette in the last 3 months that make prevalence of tobacco use 38.2%. ..... Okasha A, Karam E.Mental health services and research in the. Arab world. Acta Psychiatrica Scandinavica.

  7. Research

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    2014-04-21

    Apr 21, 2014 ... Prospective assessment of the risk of obstructive sleep apnea in ... Faculty of Clinical Sciences, College of Medicine, University of .... University Teaching Hospital Health Research Ethics Committee ... BANG, Berlin questionnaire and the American Society of .... The epidemiology of adult obstructive sleep.

  8. Research

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    2016-02-01

    Feb 1, 2016 ... University Hospital, DK-5000 Odense, Denmark, 3Center for Global Health, Institute of Clinical Research, University of Southern Denmark, DK-5000. Odense .... BHP is a Danish-Guinean Demographic Surveillance Site with a study-area .... variables such as age groups, previous military duty, history of.

  9. Research

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    2015-06-24

    Jun 24, 2015 ... related immunosuppression, previous history of TB, and pause in treatment [6]. In Brazil, researchers .... treatment, use of traditional medicines or herbs, history of TB drug side effects and treatment delay). ..... therapy for pulmonary tuberculosis in Lima Ciudad, Peru. International journal of tuberculosis and ...

  10. Research

    African Journals Online (AJOL)

    Research. May 2016, Vol. 8, No. 1 AJHPE 37. Students who enrol in occupational therapy (OT) at the. University of Kwa Zulu-Natal (UKZN), Durban, South Africa ... The latter may include becoming familiar with the disintegrating social systems in primary .... They also lacked the skills needed to adapt sessions and failed to ...

  11. Research

    African Journals Online (AJOL)

    ebutamanya

    2015-06-22

    Jun 22, 2015 ... collaboration with Makerere University, School of Public Health. We acknowledge The Family Health Research and Development Centre. (FHRDC) Uganda. Supported by Bill & Melinda Gates Institute for. Population & Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, ...

  12. Research

    African Journals Online (AJOL)

    However, a focus on competence alone is inadequate to produce graduates who are capable of adapting to the changing needs of health systems. While knowledge and technical ... shared their responses to guided questions. There were three sessions; after each session the researcher aggregated participant responses ...

  13. Research

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    2014-01-31

    Jan 31, 2014 ... by Hazarika in a population-based study in India. The researcher noted that patients' preference to the private health facilities was due mainly to their dissatisfaction with the services in the public health facilities [11]. Furthermore, the quality of the services in the private health facilities could also be a major ...

  14. Research

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    2018-03-20

    Mar 20, 2018 ... student health professionals in various institutions, both in South Africa. (SA) and internationally. ... field include dentists, dental therapists and oral hygienists in training, .... The College of Health Sciences at UKZN has four schools: clinical ..... Journal of Emerging Trends in Educational Research and Policy ...

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    2017-09-14

    Sep 14, 2017 ... Abstract. Introduction: Medical and dental students are a high-risk group for hepatitis B virus (HBV) infection which is an ... The Pan African Medical Journal - ISSN 1937-8688. ... Research ... in the College of Health Sciences and clinical students (years four to .... Hepatology International.2017 Jan; 11(1):.

  16. Research

    African Journals Online (AJOL)

    abp

    2015-01-19

    Jan 19, 2015 ... One research assistant was available to assist the learners and to answer questions while they completed the questionnaires during a classroom period. ..... PubMed | Google Scholar. 4. Hall PA, Holmqvist M, Sherry SB. Risky adolescent sexual behaviour: A psychological perspective for primary care.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Researching research

    DEFF Research Database (Denmark)

    Pais, Alexandre; Valero, Paola

    2012-01-01

    We discuss contemporary theories in mathematics education in order to do research on research. Our strategy consists of analysing discursively and ideologically recent key publications addressing the role of theory in mathematics education research. We examine how the field fabricates its object...... of research by deploying Foucault’s notion of bio-politics - mainly to address the object “learning” - and Žižek’s ideology critique - to address the object “mathematics”. These theories, which have already been used in the field to research teaching and learning, have a great potential to contribute...... to a reflexivity of research on its discourses and effects. Furthermore, they enable us to present a clear distinction between what has been called the sociopolitical turn in mathematics education research and what we call a positioning of mathematics education (research) practices in the Political....

  2. 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.

  3. 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.

  4. Path to a Research Plan

    Science.gov (United States)

    Chiaramonte, Fran

    2003-01-01

    This viewgraph presentation discusses the status and goals for the NASA OBPR Physical Science Research Program. The following text was used to summarize the presentation. The OBPR Physical Sciences Research program has been comprehensively reviewed and endorsed by National Research Council. The value and need for the research have been re-affirmed. The research program has been prioritized and resource re-allocations have been carried out through an OBPR-wide process. An increasing emphasis on strategic, mission-oriented research is planned. The program will strive to maintain a balance between strategic and fundamental research. A feasible ISS flight research program fitting within the budgetary and ISS resource envelopes has been formulated for the near term (2003-2007). The current ISS research program will be significantly strengthened starting 2005 by using discipline dedicated research facility racks. A research re-planning effort has been initiated and will include active participation from the research community in the next few months. The research re-planning effort will poise PSR to increase ISS research utilization for a potential enhancement beyond ISS IP Core Complete. The Physical Sciences research program readily integrates the cross-disciplinary requirements of the NASA and OBPR strategic objectives. Each fundamental research thrust will develop a roadmap through technical workshops and Discipline Working Groups (DWGs). Most fundamental research thrusts will involve cross-disciplinary efforts. A Technology Roadmap will guide the Strategic Research for Exploration thrust. The Research Plan will integrate and coordinate fundamental Research Thrusts Roadmaps with the Technology Roadmap. The Technology Roadmap will be developed in coordination with other OBPR programs as well as other Enterprise (R,S,M,N). International Partners will contribute to the roadmaps and through research coordination. The research plan will be vetted with the discipline

  5. The study of evaluation methodology of the aging and degradation researches

    International Nuclear Information System (INIS)

    Cho, C. J.; Park, Z. H.; Jeong, I. S.

    2001-01-01

    To judge the usefulness of aging related researches like PLIM (Plant lifetime Management) and aging related degradation, et. al. in PSR(Periodic Safety Review), the evaluation methodology of the R and D have been proposed up to now are reviewed. The infometric methodology is considered to be the optimum method for the evaluation of the nuclear related researches. And finally, to increase the objectiveness and reliability of the infometric methodology in the aging and degradation researches, the indexes of safety, technology and economics are introduced. From this study, the infometric methodology has the advantage of the actual engineering evaluation in the nuclear related researches with other methodologies, but for the further research, the effective construction of DB and survey of various statistics in the technical reports and papers are needed

  6. 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.

  7. Instrument development for materials science research at WNR

    International Nuclear Information System (INIS)

    Eckert, J.; Silver, R.N.; Soper, A.; Vergamini, P.J.; Goldstone, J.; Larson, A.; Seeger, P.A.; Yarnell, J.

    1980-01-01

    The neutron scattering program at the Los Alamos spallation neutron source is based on the operational WNR facility which provides up to 11 μA of 800 MeV protons to a target in pulse widths up to 8 μs at 120 Hz. The immediate goals of the program are: to gain experience with neutron instrumentation at spallation neutron sources; and to explore the scientific potential for condensed matter research at these sources. The proton storage ring (PSR) funded for construction will provide 100 μA in 0.27 μs pulses at 12 Hz, therefore greatly improving intensity, time-of-flight (TOF) resolution, and repetition rate. The initial emphasis, given limited manpower and resources, has been placed on developing a set of prototype instruments which are relatively easy to implement and which take advantage of the unique characteristics of the present WNR when compared with reactor neutron sources

  8. Constraints on Estimation of Radius of Double Pulsar PSR J0737-3039A and Its Neutron Star Nuclear Matter Composition

    Science.gov (United States)

    Yang, Yi-Yan; Chen, Li; Linghu, Rong-Feng; Zhang, Li-Yun; Taani, Ali

    2017-12-01

    Not Available Supported by the National Program on Key Research and Development Project under Grant No 2016YFA0400801, the National Natural Science Foundation of China under Grant Nos 11173034, 11673023 and 11364007, the Fundamental Research Funds for the Central University, the Key Support Disciplines of Theoretical Physics of Guizhou Province Education Bureau under Grant No ZDXK[2015]38, and the Youth Talents Project of Science and Technology in Education Bureau of Guizhou Province under Grant No KY[2017]204.

  9. Researcher / Researched: Repositioning Research Paradigms

    Science.gov (United States)

    Meerwald, Agnes May Lin

    2013-01-01

    "Researcher / Researched" calls for a complementary research methodology by proposing autoethnography as both a method and text that crosses the boundaries of conventional and alternative methodologies in higher education. Autoethnography rearticulates the researcher / researched positions by blurring the boundary between them. This…

  10. 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

  11. Original Research Original Research

    African Journals Online (AJOL)

    RAGHAVENDRA

    To this effect, two basic research with these research ... In this area, Ho conducted a research on a topic “Effectiveness o .... questioning, making a list, clustering, preparing a scratch .... three data collection instruments by using quantitative and.

  12. Selected concrete spent fuel storage cask concepts and the DOE/PSN Cooperative Cask Testing Program

    International Nuclear Information System (INIS)

    Creer, J.M.; McKinnon, M.A.; Collantes, C.E.

    1990-01-01

    To date, water pools, metal casks, horizontal concrete modules, and modular vaults have been used to store the major quantity of commercial light water reactor spent nuclear fuel. Recently, vertical concrete dry storage casks have received consideration for storage of spent nuclear fuel. This paper reviews the evolution of the development of selected vertical concrete dry storage casks and outlines a cooperative cask testing (heat transfer and shielding) program involving the US Department of Energy and Pacific Sierra Nuclear Associates. Others participating in the cooperative program are Pacific Northwest Laboratory; EG ampersand G Idaho, Inc.; Wisconsin Electric Power Company; and the Electric Power Research Institute. 28 refs., 14 figs

  13. Research News

    Science.gov (United States)

    ... Research News Share this page Facebook Twitter Email Research News Research News Quarterly Updates Research Call Archive ... Clinical Trials in MS Learn More Become a Research Champion An MS Research Revolution Support MS Research ...

  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. Original Research Original Research

    African Journals Online (AJOL)

    RAGHAVENDRA

    Twelve gra using simple random sampling technique and an En ... Science, Technology and Arts Research Journ. Sci. Technol. ... he quantitative data disclosed lower student scores, .... work on relating the title to students' lives, motivating,.

  17. Original Research Original Research

    African Journals Online (AJOL)

    RAGHAVENDRA

    genetic improvement and lack of organized market system are the ... Science, Technology and Arts Research Journ. Sci. ... located in Oromia Regional States in the western. Ethiopia ..... district in the western Ethiopia that reported the price of.

  18. Original Research Original Research

    African Journals Online (AJOL)

    RAGHAVENDRA

    mountage types (ply wood, cartoon made, Banana leaf, pl leaf montages) and ... at Melkassa Agricultural Research Center in the sericulture ry during 2011-2013 ..... (2009) also study qualitative improvement in terms of economic gained by.

  19. Artistic research, context research

    Directory of Open Access Journals (Sweden)

    Ricardo Benjamín Toledo Castellanos

    2012-06-01

    Full Text Available Some concepts in contemporary art works, dealing with some life aspects and passed through the sensitive and expressive test, are formulated in this paper and shed light on the foundation of researches about singular phenomenons of the existence. For this, it is argued that there are researches belonging to arts, fundamental researches that compromise the certainty of the assumptions where the sense system of a context has its bases (epoch, culture, nation, region. These researches come ahead of the researches of the rational-discursive enunciation fields, given that the last ones haven’t passed any protocol accepted yet by any community. To bring into play the certainty is done by a cognitive movement named by Martin Heidegger unconcealment [Unverborgenheit], and it consist on the interruption of the habituality of the beings who form the (trustworthy family setting to put into perspective the fundamental structures that allow to produce its sense. The unconcealment, typical in art and in creative actions, sets up an event that stops the solidity of the established (social, ethical, technical, scientific, philosophical order, and unleashes conditions for changing the lifestyles hold until then.

  20. Original Research Original Research

    African Journals Online (AJOL)

    RAGHAVENDRA

    research is to determine the level of interference ... perceived in the foreign language production (Aber. 2013). ... Accordingly, it is important to help learners reduce th ... Official International Journal of Wollega University, Ethiopia .... e learning process, learners .... them to self-evaluate errors and improve their English writing ...

  1. Original Research Original Research

    African Journals Online (AJOL)

    User

    This research pape of mobile advertising in the mind of customers espec. Delhi, India. Further it also tries to find out the go product / services due to mobile advertising. INTRODUCTION. Mobile advertising is a brand new phenomenon. Yunos et al. (2003) defined mobile advertising as marketing and advertising activities.

  2. Original Research Original Research

    African Journals Online (AJOL)

    User

    2013-06-19

    Jun 19, 2013 ... After collecting knowledge, attitude and behavior inventory questionnaire, the researcher conducted. FGDs that contain 1 male and 1 female student from grade 9, 10, 11 and 12 for 2 hours in two sessions (1 hour for each session) which are selected with the support of room teachers. Due to limited time to ...

  3. Cancer Research

    Science.gov (United States)

    NCI is the nation's leader in cancer research. Learn more about NCI's cancer research areas, key initiatives, progress made in cancer research, and resources for researchers like research tools, specimens and data.

  4. Research Library

    Science.gov (United States)

    Los Alamos National Laboratory Research Library Search Site submit Contact Us | Remote Access Standards Theses/Dissertations Research Help Subject Guides Library Training Video Tutorials Alerts Research Library: delivering essential knowledge services for national security sciences since 1947 Los

  5. Research vessels

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.

    The role of the research vessels as a tool for marine research and exploration is very important. Technical requirements of a suitable vessel and the laboratories needed on board are discussed. The history and the research work carried out...

  6. Research organizations

    DEFF Research Database (Denmark)

    Larsen, Bøje; Aagaard, Peter

    in Copenhagen - we argue that a post-rational form of research activity is emerging which revert these features. We term this new type of research "enchanted research", "sciencetainment" and "Mode2-b research". The factors that facilitate this development include the boring style of conventional research......, growing competition for research funds, more project funding compared to institutional funding and a demand for accountability. Countervailing forces also exist, however....

  7. Action Research and Interactive Research

    DEFF Research Database (Denmark)

    Svensson, lennart; Nielsen, Kurt Aagaard

    2006-01-01

    The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research.......The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research....

  8. Researcher Positioning

    DEFF Research Database (Denmark)

    Khawaja, Iram; Mørck, Line Lerche

    2009-01-01

    involvement by the researcher, which challenges traditional perspectives onresearch and researcher positioning. A key point in this regard is the importance ofconstant awareness of and reflection on the multiple ways in which one's positioningas a researcher influences the research process. Studying the other...

  9. GLCF: Research

    Science.gov (United States)

    Global Land Cover Facility About GLCF Research Publications Data & Products Gallery Library Services Contact Site Map Go Research The Global Land Cover Facility is a research center focusing on the GLCF in developing forest change products. Past research efforts were directed at boreal forests in

  10. Qualitative research.

    Science.gov (United States)

    Gelling, Leslie

    2015-03-25

    Qualitative research has an important role in helping nurses and other healthcare professionals understand patient experiences of health and illness. Qualitative researchers have a large number of methodological options and therefore should take care in planning and conducting their research. This article offers a brief overview of some of the key issues qualitative researchers should consider.

  11. Researcher positioning

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Khawaja, Iram

    2009-01-01

    abstract  This article focuses on the complex and multi-layered process of researcher positioning, specifically in relation to the politically sensitive study of marginalised and ‘othered' groups such as Muslims living in Denmark. We discuss the impact of different ethnic, religious and racial...... political and personal involvement by the researcher, which challenges traditional perspectives on research and researcher positioning. A key point in this regard is the importance of constant awareness of and reflection on the multiple ways in which one's positioning as a researcher influences the research...

  12. Research Design

    DEFF Research Database (Denmark)

    2019-01-01

    Gunnar Scott Reinbacher (editor) Antology.  Research Design : Validation in Social Sciences. Gunnar Scott Reinbacher: Introduction. Research design and validity. 15p Ole Riis: Creative Research design. 16 p Lennart Nørreklit: Validity in Research Design. 24p Gitte Sommer Harrits: Praxeological...... Scott Reinbacher: Multidisciplinary Research Designs in Problem Based Research. The case of an european project on chronical diseases, the Tandem project (Training Alternmative Networking Skills in Diabetes Management). 15p Niels Nørgaard Kristensen: A qualitative bottom up approach to post modern...... knowledge: An integrated strategy for combining "explaining" and "understanding". 22p Heidi Houlberg Salomonsen & Viola Burau: Comparative research designs. 40p Rasmus Antoft & Heidi Houlberg Salomonsen: Studying organizations by a Pragmatic Research Design: the case of qualitative case study  designs. 31p...

  13. Research Review

    OpenAIRE

    Anonymous

    1983-01-01

    Research Reviewed: "The Adjustment of Nominal Interest Rates to Inflation: A Review of Recent Literature"; "Role of Government in a Market Economy"; "Economic Analysis and Agricultural Policy"; "Agricultural Research Policy"

  14. Research design

    NARCIS (Netherlands)

    Tobi, Hilde; Kampen, Jarl K.

    2018-01-01

    Many of today’s global scientific challenges require the joint involvement of researchers from different disciplinary backgrounds (social sciences, environmental sciences, climatology, medicine, etc.). Such interdisciplinary research teams face many challenges resulting from differences in training

  15. Ethnographic research

    NARCIS (Netherlands)

    Vermeulen, J.; Koster, M.; Hulst, M. van; Bearfield, D.A.; Dubnick, M.J.

    2015-01-01

    This entry outlines three aspects of ethnographic research. First, we describe in what way ethnographic research implies a distinct way of knowing. Second, we discuss the use of qualitative methods in ethnographic research. Third, we take up the role of writing, which is both a way of documenting

  16. Descriptive Research

    DEFF Research Database (Denmark)

    Wigram, Anthony Lewis

    2003-01-01

    Descriptive research is described by Lathom-Radocy and Radocy (1995) to include Survey research, ex post facto research, case studies and developmental studies. Descriptive research also includes a review of the literature in order to provide both quantitative and qualitative evidence of the effect...... starts will allow effect size calculations to be made in order to evaluate effect over time. Given the difficulties in undertaking controlled experimental studies in the creative arts therapies, descriptive research methods offer a way of quantifying effect through descriptive statistical analysis...

  17. Research misconduct

    International Nuclear Information System (INIS)

    Gilbert, F.J.; Denison, A.R.

    2003-01-01

    Good research practice is important to the scientific community. An awareness of what constitutes poor practice is important. Various types of research misconduct are defined in this article. The extent of research misconduct in the field of radiology has been assessed by contacting five English language radiology journals. Redundant or duplicate publication has been reported infrequently, Radiology (1), American Journal of Roentgenology (3), Clinical Radiology (3), British Journal of Radiology (2) and European Radiology (1). The issue of how the radiology community might tackle research misconduct is discussed with reference to guidance from the Medical Research Council, the Wellcome Trust and the Committee of Publication Ethics

  18. Research circles

    DEFF Research Database (Denmark)

    Nordentoft, Helle Merete; Thomsen, Rie; Möller, Jonas

    lifelong guidance policies. This paper presents `research circles´ as a way to develop guidance practices through long-term research relationships between practice and research. Research circles support a bottom up approach to policy development just like ELGPN considers to be necessary and required...... of their habitual pedagogical role and enables them to observe and analyze their own practice. In conclusion, this methodological approach to the development of guidance practices introduces a combination between theory and practice that meets current needs of practice, policy and research....

  19. Editorial -Research! Research! Research! What are Thou?

    Directory of Open Access Journals (Sweden)

    Ashok Shyam

    2013-04-01

    Full Text Available Being in field of Orthopaedic research since last 6 years, I have personally been witness to the rapid change in landscape of Othopaedic Research and also medical research in general. The sheer volumes of publications is overwhelming to the extent of being mostly ineffective in providing significant positive addition to the current literature. “There are too many variables” is one of my favorite phrase when I start to explain something to myself. Looking at as many variables as we can think of, makes us understand concepts within the limitations of given variables. Something similar to Ashby’s law that we spoke about in last Editorial [1]. However when we try to apply this to word ‘Research’ the amount of subjective stereotype that is associated with the word defeats all attempt to decipher and communicate clearly. Originally word Research derived from French ‘Researche’ simply means ‘Pursuit of Knowledge’. We as medical practitioners in search of better treatment for our patients are always in pursuit of knowledge. This knowledge is mostly build individually and is learned from individual experience and learning. This is a subjective body of knowledge and this is what makes one surgeon better than another. But is this ‘Research’? Yes it is Research and it serves the main purpose of medical research that is to improve the treatment given to patients. However this is a limited form of research, limited by individual’s ability and capacity. It also does not subject itself to rigorous ‘scientific methods’ and may not be acceptable to a community of ‘Modern Researchers’. Another form of Research of pursuit of knowledge is again from the clinics and from reading journals and books. A collaboration of clinical experience and written word adds a more thoughtful way of pursuing knowledge. This I think is the way majority of medical practitioners acquire knowledge. This keeps them updated and also helps them provide good

  20. Research ethics for clinical researchers.

    Science.gov (United States)

    Harnett, John D; Neuman, Richard

    2015-01-01

    This chapter describes the history of the development of modern research ethics. The governance of research ethics is discussed and varies according to geographical location. However, the guidelines used for research ethics review are very similar across a wide variety of jurisdictions. The paramount importance of protecting the privacy and confidentiality of research participants is discussed at length. Particular emphasis is placed on the process of informed consent, and step-by-step practical guidelines are described. The issue of research in vulnerable populations is touched upon and guidelines are provided. Practical advice is provided for researchers to guide their interactions with research ethics boards. Issues related to scientific misconduct and research fraud are not dealt with in this paper.

  1. Research Review: Doing Artistic Research

    Science.gov (United States)

    Serig, Dan

    2012-01-01

    In this review, the author focuses on the pragmatic consideration: How do artists do artistic research? Artistic research in the context of this review is about the connections and relationships among three primary domains: (1) the arts; (2) higher education; and (3) arts education. Broadly stated, all artists do research when they do art--whether…

  2. Centering research

    DEFF Research Database (Denmark)

    Katan, Lina Hauge; Baarts, Charlotte

    Research-based teaching has long been a distinguishing trait of higher education. Engaging students in research-like processes has been employed to great effect in learning and continues to be encouraged by educational studies. The literature on this subject reflects how ‘technical’ or ‘field......’ exercises tend to dominate the common understandings of research-based learning. Here we address a specific area of inquiry overlooked by previous studies: whether and how reading, thinking and writing indeed share the same learning potentials as the practical foundation for research-based teaching....... In the humanities and social sciences, integrated acts of reading, writing and thinking account for an obvious and substantial overlap in student and researcher practices, creating a clear opportunity for research-based teaching. Moreover, our empirical data point to reading, thinking and writing as quintessential...

  3. Animal research

    DEFF Research Database (Denmark)

    Olsson, I.A.S.; Sandøe, Peter

    2012-01-01

    This article presents the ethical issues in animal research using a combined approach of ethical theory and analysis of scientific findings with bearing on the ethical analysis. The article opens with a general discussion of the moral acceptability of animal use in research. The use of animals...... in research is analyzed from the viewpoint of three distinct ethical approaches: contractarianism, utilitarianism, and animal rights view. On a contractarian view, research on animals is only an ethical issue to the extent that other humans as parties to the social contract care about how research animals...... are faring. From the utilitarian perspective, the use of sentient animals in research that may harm them is an ethical issue, but harm done to animals can be balanced by benefit generated for humans and other animals. The animal rights view, when thoroughgoing, is abolitionist as regards the use of animals...

  4. Research methodology

    DEFF Research Database (Denmark)

    Kuada, John

    This book deals with how students should use of research methods in their university projects. It aims at helping students in developing comprehensive research strategies for their projects. It also provides introduction to issues of philosophy of science as applied in the social sciences....... That is it provides them with a fair understanding of the root assumptions that guide researchers in their investigations and how these assumptions inform their theoretical thinking and choice of methods....

  5. 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)

  6. 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.

  7. 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...

  8. Clinical Research

    DEFF Research Database (Denmark)

    Christensen, Irene

    2016-01-01

    This paper is about the logic of problem solving and the production of scientific knowledge through the utilisation of clinical research perspective. Ramp-up effectiveness, productivity, efficiency and organizational excellence are topics that continue to engage research and will continue doing so...... for years to come. This paper seeks to provide insights into ramp-up management studies through providing an agenda for conducting collaborative clinical research and extend this area by proposing how clinical research could be designed and executed in the Ramp- up management setting....

  9. Letterform research

    DEFF Research Database (Denmark)

    Beier, Sofie

    2016-01-01

    This paper looks into the history of letterform research and discusses why the discipline has yet to make the big break within design research. By highlighting two of the most popular focus areas (letter distinctiveness and the role of serifs) and by discussing various forms of methodological...... shortcomings, the paper suggests that future research into letterforms should (1) draw on results from the field of reading research (2) be based on test material informed by design knowledge and (3) move away from the former tendency of looking for universal answers....

  10. Plant Research

    Science.gov (United States)

    1990-01-01

    The Land's agricultural research team is testing new ways to sustain life in space as a research participant with Kennedy Space Center's Controlled Ecological Life Support System (CELSS). The Land, sponsored by Kraft General Foods, is an entertainment, research, and education facility at EPCOT Center, part of Walt Disney World. The cooperative effort is simultaneously a research and development program, a technology demonstration that provides the public to see high technology at work and an area of potential spinoff: the CELSS work may generate Earth use technology beneficial to the hydroponic (soilless growing) vegetable production industries of the world.

  11. Research Review

    OpenAIRE

    Anonymous

    1981-01-01

    Research Reviewed: "Global Modeling After Its First Decade"; "Monthly Food Price Forecasts"; "Costs of Marketing Slaughter Cattle: Computerized versus Conventional Auction Systems"; "Survival Strategies for Agricultural Cooperatives"

  12. Research, Research Gap and the Research Problem

    OpenAIRE

    Dissanayake, D.M.N.S.W.

    2013-01-01

    Mainly, due to new scientific inquiries and technological advancements Knowledge becomes obsolete. So it creates a dilemma where the applicability of so called theories and models which we learnt in class can still be applied to solve problems? Thus, the scholars bring the notion of RESEARCH as a definite solution which enriches the existing understanding of a phenomenon. This can be either a theory testing or a theory extension (theory building) approach. In fact, gap identification and form...

  13. Research Ethics

    Science.gov (United States)

    Dooly, Melinda; Moore, Emilee; Vallejo, Claudia

    2017-01-01

    Qualitative research, especially studies in educational contexts, often brings up questions of ethics because the study design involves human subjects, some of whom are under age (e.g. data collected in primary education classrooms). It is not always easy for young researchers to anticipate where ethical issues might emerge while designing their…

  14. Research Review

    Science.gov (United States)

    Serig, Dan, Ed.

    2010-01-01

    This research review is dedicated to the memory of William Safire (1929-2009). A visionary leader, Safire brought other visionaries, researchers, educators, artists, and policymakers together to explore the confluence of arts education and neuroscience. He fostered the new field of neuroeducation in his work as chair of The Dana Foundation in…

  15. Research Review

    Science.gov (United States)

    Serig, Dan

    2011-01-01

    In this review, the author explores an often-used process in research--the mind map. He uses this method in his own research and artwork. He also uses this extensively with students, particularly master students when they are trying to surround issues in their thesis projects. Mind maps are closely associated with brainstorming, as brainstorming…

  16. Remote Research

    CERN Document Server

    Tulathimutte, Tony

    2011-01-01

    Remote studies allow you to recruit subjects quickly, cheaply, and immediately, and give you the opportunity to observe users as they behave naturally in their own environment. In Remote Research, Nate Bolt and Tony Tulathimutte teach you how to design and conduct remote research studies, top to bottom, with little more than a phone and a laptop.

  17. Preeclampsia Research

    Science.gov (United States)

    ... one of these studies, DESPR researchers examined tumor necrosis factor (TNF)-alpha in the blood of women ... researchers examined blood concentrations of sENG, PlGF, soluble vascular endothelial growth factor receptor-1 (sVEGFR‑1), and ...

  18. Research supervision

    African Journals Online (AJOL)

    This gap in the training of nurse educators may result in low in- and output in the research ... Which factors influence the manner in which PG nursing students perceive the .... sample consisted of females (83.9%; n=47), with males representing only. 16.1% (n=9). ..... Winsett and Cashion[20] assert that a research method.

  19. Design Research

    DEFF Research Database (Denmark)

    Design Research is a new interdisciplinary research area with a social science orientation at its heart, and this book explores how scientific knowledge can be put into practice in ways that are at once ethical, creative, helpful, and extraordinary in their results. In order to clarify the common...... aspects – in terms of features and approaches – that characterize all strands of research disciplines addressing design, Design Research undertakes an in depth exploration of the social processes involved in doing design, as well as analyses of the contexts for design use. The book further elicits...... ‘synergies from interdisciplinary perspectives’ by discussing and elaborating on differing academic perspectives, theoretical backgrounds, and design concept definitions, and evaluating their unique contribution to a general core of design research. This book is an exciting contribution to this little...

  20. Research report

    International Nuclear Information System (INIS)

    Whitley, J.E.

    1990-07-01

    The SURRC (Scottish Universities Research and Reactor Centre) is a multidisciplinary research centre shared by a consortium of Scottish Universities. Funding is jointly by the University Funding Committee and commercially from Research Councils, government departments and industry. The focus of research lies in earth, environmental and biomedical sciences. The research activities are discussed under the following headings: environmental radioactivity and nuclear geochemistry, neutron activation analysis, inductively coupled plasma-mass spectrometry, body composition studies, stable isotopes in biological sciences, nuclear physics, luminescence dating and dosimetry radiation effects in electrical insulation, gamma-ray irradiation processing, radiogenic isotopes in geology, stable isotope geology, laser microprobe mass spectrometry for geology and NERC Radiocarbon Laboratory work. There are also reports on the reactor itself; reactor operation, production of radioactive isotopes and application of radioactive tracers. The educational aspects of the Centre, safety aspects, staffing, funding and all publications are reported. (UK)

  1. Survey research.

    Science.gov (United States)

    Alderman, Amy K; Salem, Barbara

    2010-10-01

    Survey research is a unique methodology that can provide insight into individuals' perspectives and experiences and can be collected on a large population-based sample. Specifically, in plastic surgery, survey research can provide patients and providers with accurate and reproducible information to assist with medical decision-making. When using survey methods in research, researchers should develop a conceptual model that explains the relationships of the independent and dependent variables. The items of the survey are of primary importance. Collected data are only useful if they accurately measure the concepts of interest. In addition, administration of the survey must follow basic principles to ensure an adequate response rate and representation of the intended target sample. In this article, the authors review some general concepts important for successful survey research and discuss the many advantages this methodology has for obtaining limitless amounts of valuable information.

  2. Research reactors

    International Nuclear Information System (INIS)

    Merchie, Francois

    2015-10-01

    This article proposes an overview of research reactors, i.e. nuclear reactors of less than 100 MW. Generally, these reactors are used as neutron generators for basic research in matter sciences and for technological research as a support to power reactors. The author proposes an overview of the general design of research reactors in terms of core size, of number of fissions, of neutron flow, of neutron space distribution. He outlines that this design is a compromise between a compact enough core, a sufficient experiment volume, and high enough power densities without affecting neutron performance or its experimental use. The author evokes the safety framework (same regulations as for power reactors, more constraining measures after Fukushima, international bodies). He presents the main characteristics and operation of the two families which represent almost all research reactors; firstly, heavy water reactors (photos, drawings and figures illustrate different examples); and secondly light water moderated and cooled reactors with a distinction between open core pool reactors like Melusine and Triton, pool reactors with containment, experimental fast breeder reactors (Rapsodie, the Russian BOR 60, the Chinese CEFR). The author describes the main uses of research reactors: basic research, applied and technological research, safety tests, production of radio-isotopes for medicine and industry, analysis of elements present under the form of traces at very low concentrations, non destructive testing, doping of silicon mono-crystalline ingots. The author then discusses the relationship between research reactors and non proliferation, and finally evokes perspectives (decrease of the number of research reactors in the world, the Jules Horowitz project)

  3. 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. ∗.

  4. Research reactors

    International Nuclear Information System (INIS)

    Kowarski, L.

    1955-01-01

    It brings together the techniques data which are involved in the discussion about the utility for a research institute to acquire an atomic reactor for research purposes. This type of decision are often taken by non-specialist people who can need a brief presentation of a research reactor and its possibilities in term of research before asking advises to experts. In a first part, it draws up a list of the different research programs which can be studied by getting a research reactor. First of all is the reactor behaviour and kinetics studies (reproducibility factor, exploration of neutron density, effect of reactor structure, effect of material irradiation...). Physical studies includes study of the behaviour of the control system, studies of neutron resonance phenomena and study of the fission process for example. Chemical studies involves the study of manipulation and control of hot material, characterisation of nuclear species produced in the reactor and chemical effects of irradiation on chemical properties and reactions. Biology and medicine research involves studies of irradiation on man and animals, genetics research, food or medical tools sterilization and neutron beams effect on tumour for example. A large number of other subjects can be studied in a reactor research as reactor construction material research, fabrication of radioactive sources for radiographic techniques or applied research as in agriculture or electronic. The second part discussed the technological considerations when choosing the reactor type. The technological factors, which are considered for its choice, are the power of the reactor, the nature of the fuel which is used, the type of moderator (water, heavy water, graphite or BeO) and the reflector, the type of coolants, the protection shield and the control systems. In the third part, it described the characteristics (place of installation, type of combustible and comments) and performance (power, neutron flux ) of already existing

  5. Researching Undergraduate Social Science Research

    Science.gov (United States)

    Rand, Jane

    2016-01-01

    The experience(s) of undergraduate research students in the social sciences is under-represented in the literature in comparison to the natural sciences or science, technology, engineering and maths (STEM). The strength of STEM undergraduate research learning environments is understood to be related to an apprenticeship-mode of learning supported…

  6. Action Research and Interactive Research

    DEFF Research Database (Denmark)

    First part of the book is written by senior researchers on specific issues like validity, gender, new forms of organisations, methodologies and methods, earlier and new trends. - The second part of the book is written by doctoral students reporting experiences doing action research in their PhD-projects....

  7. Research Staff | Photovoltaic Research | NREL

    Science.gov (United States)

    Research Staff Research Staff desc Greg Wilson Center Director Dr. Greg Wilson is the Director of @nrel.gov 303-384-6649 Bosco, Nicholas Staff Scientist Nick.Bosco@nrel.gov 303-384-6337 Braunecker, Wade IV-Physics Michael.Deceglie@nrel.gov 303-384-6104 Deline, Chris Staff Engineer Chris.Deline@nrel.gov

  8. Research Article

    African Journals Online (AJOL)

    2016-06-13

    Jun 13, 2016 ... Journal of Fundamental and Applied Sciences is licensed under a Creative Commons Attribution-NonCommercial 4.0. International License. Libraries .... research on thinking styles, increases understanding and awareness of ...

  9. Research Article

    African Journals Online (AJOL)

    2016-06-15

    Jun 15, 2016 ... ve of this research is to identify, analyze, and prioritize factors effec .... In Iran, Fallahnejad identified 43 factors of delay for gas pipeline ... contractor include, financial problems, material management issues, planning and time.

  10. Research Article

    African Journals Online (AJOL)

    2016-06-13

    Jun 13, 2016 ... emerging drug-resistant pathogens in research programme around the world. This article reviews the history of antibiotics, different types of antibiotics, .... of the plasma membrane; these changes result in the loss of important ...

  11. Disaster Research

    DEFF Research Database (Denmark)

    Given the tendency of books on disasters to predominantly focus on strong geophysical or descriptive perspectives and in-depth accounts of particular catastrophes, Disaster Research provides a much-needed multidisciplinary perspective of the area. This book is is structured thematically around key...... approaches to disaster research from a range of different, but often complementary academic disciplines. Each chapter presents distinct approaches to disaster research that is anchored in a particular discipline; ranging from the law of disasters and disaster historiography to disaster politics...... and anthropology of disaster. The methodological and theoretical contributions underlining a specific approach to disasters are discussed and illustrative empirical cases are examined that support and further inform the proposed approach to disaster research. The book thus provides unique insights into fourteen...

  12. Research Article

    African Journals Online (AJOL)

    2016-05-15

    May 15, 2016 ... We are listed under Research Associations category. .... important squares, Hidalgo Square in Mexico City, Plaza Santa Anna in Spain and Antarvasna ... source material efficiency; understand the power of God and a spirit of ...

  13. Air Research

    Science.gov (United States)

    EPA's air research provides the critical science to develop and implement outdoor air regulations under the Clean Air Act and puts new tools and information in the hands of air quality managers and regulators to protect the air we breathe.

  14. RESEARCH NOTE

    Indian Academy of Sciences (India)

    Navya

    RESEARCH NOTE. CDKN2A and MC1R ... Department of Pharmacy and Department of Nursing, School of Health Sciences, Frederick. University, Nicosia ..... Appears with highest frequency in African, Asian-Indian, and Papua. New Guinean ...

  15. RESEARCH ARTICLE

    Indian Academy of Sciences (India)

    2017-01-11

    Jan 11, 2017 ... ... in a Techne thermocycler, amplified products were multiplexed ..... attempt and the basis for future research and conservation planning in A. altamirani. ..... Zambrano L., Valiente E. and Vander Zanden M.J. 2010 Food web ...

  16. Researcher Biographies

    Science.gov (United States)

    Operations Technology Exchange Initiating Partnerships University Partners Government Partners Industry ., Mechanical Engineering, Unversity of California, Davis (1986); M.M. San Francisco Conservatory of Music (1989 Aerospace Engineering Department, as well as Program Manager of the automotive industry research consortium

  17. Research Article

    African Journals Online (AJOL)

    2016-05-15

    May 15, 2016 ... Architecture, energy, technology and architecture research, a member of ... Keywords: Building Automation, Intelligent Management, ..... Ability to set activate lighting and ventilation systems in smart entry and exit car parking.

  18. Research needs

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Research needs were identified during working sessions for several potential separation options. These options include sequestering agents, solvent extraction, membranes, solid sorbents, novel approaches, organic separation and destruction methods, and radiation and chemical stability of separation materials

  19. Research materials

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Development of techniques required for the preparation and characterization of ultrahigh-purity and controlled-impurity research specimens of interest to ORNL and other ERDA installations is described

  20. Research Article

    African Journals Online (AJOL)

    pc

    2018-05-01

    May 1, 2018 ... athology, school of medicine, Clinical Research Development Unit Be ospital .... other devices (such as toys in the pediatric ward) in the transmission of hospital .... Did not show any significant correlation between gender and.

  1. Malaria Research

    Science.gov (United States)

    ... with facebook share with twitter share with linkedin Malaria Go to Information for Researchers ► Credit: NIAID Colorized ... for the disease. Why Is the Study of Malaria a Priority for NIAID? Roughly 3.2 billion ...

  2. Research Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Centers for Medicare and Medicaid Services (CMS) research efforts span many topics, methods, and interests. Some projects address the Agencys immediate...

  3. Research Article

    African Journals Online (AJOL)

    2016-06-13

    Jun 13, 2016 ... Agricultural Research and Education Organization. 2 ... ornamental flowers, are important factors that shows necessity of extension of safflower ... neutral for seed yield and oil production, but when safflower is grown for the ...

  4. Aging research

    International Nuclear Information System (INIS)

    Ross, D.F. Jr.

    1988-01-01

    The USNRC Office of Nuclear Regulatory Research has developed a program for nuclear plant aging research (NPAR) to achieve an understanding of nuclear plant aging, its potential effects on safety, and methods for its detection and mitigation, sufficient for addressing safety and regulatory issues and supporting regulatory decisions on issues. Specifically, the NRC has aggressive research and regulatory programs associated with aging effects on piping, steam generators, containments, structures, and electrical and mechanical systems and components. In addition to safety assessment for the original license period for nuclear power plants, this aging information will be extremely useful in providing technical bases for efficient and effective regulation associated with possible license extension. This paper discusses the major activities of USNRC sponsored aging research program and recommends an approach to manage and handle aging at nuclear power plants

  5. Original Research

    African Journals Online (AJOL)

    2013-09-24

    Sep 24, 2013 ... the observers' lacks of visual research skills, they pay an equal attention to physical and social ... fewer comments' of observers on visual irregularities and diffusions in managing signboards, urban graffiti ..... narrative. Visual ...

  6. Original Research

    African Journals Online (AJOL)

    2012-12-15

    Dec 15, 2012 ... Science, Technology and Arts Research Journal. Oct-Dec 2012 ... Teachers' Perceptions and Practices of Active Learning in Haramaya ..... Third, data gathering tools ... from the numerical values assigned to the degree.

  7. Latvian research

    International Nuclear Information System (INIS)

    1992-12-01

    The Latvian Council of Science asked the Danish Research Councils and the Danish Academy for Technical Sciences for help in evaluating Latvian scientific research. The background for this request was the Latvian desire to stimulate an approach towards full integration in the European society. Based on reports, site visits and interviews, 19 panels of experts covering all subject areas prepared evaluation reports. These detailed evaluations of actual research projects are included in the publication in addition to general recommendations. The panels recommend that Latvian authorities take into consideration when planning scientific research, especially with regard to those branches which contribute to the industrial development and social and economic sciences, that a balance should be made between long range basic, and short range applied, science activities. Despite the very serious economic conditions in Latvia, it was also advised that immediate measures should be taken to ensure a stable funding of the research system as the future development of Latvian society is dependent on the stability and high quality of its research activities. Other recommendations are given in detail. (AB)

  8. Is operations research really research?

    African Journals Online (AJOL)

    Other concepts that are associated with academic research include rigour, .... When a practitioner applies a standard tool, such as linear programming, to solve a ... solving the problem, but he is not adding anything new to the body of OR ...

  9. Quantitative research.

    Science.gov (United States)

    Watson, Roger

    2015-04-01

    This article describes the basic tenets of quantitative research. The concepts of dependent and independent variables are addressed and the concept of measurement and its associated issues, such as error, reliability and validity, are explored. Experiments and surveys – the principal research designs in quantitative research – are described and key features explained. The importance of the double-blind randomised controlled trial is emphasised, alongside the importance of longitudinal surveys, as opposed to cross-sectional surveys. Essential features of data storage are covered, with an emphasis on safe, anonymous storage. Finally, the article explores the analysis of quantitative data, considering what may be analysed and the main uses of statistics in analysis.

  10. Management research

    International Nuclear Information System (INIS)

    Berry, M.

    1988-01-01

    The 1988 progress report of the Management Research center (Polytechnic School, France), is presented. The Center research programs include the management of different organizations, such as industry, administrative systems, hospitals and cultural systems. The investigations performed concern the improvement and better knowledge of the new methods of analysis: the role of the speech, the logic conflicts; the crisis development, symptoms and effects; the relationship between the management practices and the prevailing ideas or theories. The approach adopted by the scientists involves the accurate analysis of the essential management activities. The investigations carried out in 1988 are summarized. The published papers, the congress communications and the thesis are listed [fr

  11. Whey research

    Energy Technology Data Exchange (ETDEWEB)

    Evans, E W

    1980-01-01

    A brief discussion of the composition of whey and its nutritional potential is followed by consideration of the less well- known areas of research in whey technology. These include the utilization of whole whey and problems of whey taint; use of lactose, by modification to lactitol, in breadmaking or as a binder for powders such as iron oxide fines in the steel industry; food uses of whey proteins e.g. in cheese, breadmaking and 'prudent diet' foods; pharmaceutical uses of whey protein concentrates as a source of lactoperoxidase; and technological research on membrane processes and ion-exchange fractionation of whey proteins.

  12. Research evaluation

    DEFF Research Database (Denmark)

    Pedersen, David Budtz

    2014-01-01

    decisions that have marked the period since the first edition was researched and published. In addition, to help make ESTE more global and interdisciplinary in scope and reach, the second edition will engage consultants from ethics centers around the world, and will feature the revised title Ethics, Science...

  13. Research Note:

    DEFF Research Database (Denmark)

    Behuria, Pritish; Buur, Lars; Gray, Hazel

    2017-01-01

    its core conceptual and methodological features. This Research Note starts by setting out our understanding of political settlements and provides an overview of existing political settlements literature on African countries. The note then explores how the key concept of ‘holding power’ has been...

  14. Research Article

    African Journals Online (AJOL)

    2016-06-18

    Jun 18, 2016 ... Available online at http://www.jfas.inf nd Applied Sciences is licensed under a Creative Commons Attribution-NonCommercial 4.0 e. Libraries Resource Directory. We are listed under Research Associations category. L INFORMATION BASED SCHOLARY PAPER RECOMMEN. SYSTEM USING BIG DATA ...

  15. Research Blog

    NARCIS (Netherlands)

    Jautze, K.J.

    2014-01-01

    Welcome to my personal research blog. I'm a PhD candidate from the Netherlands who has an interest in language and literature. In the project The Riddle of Literary Quality my colleagues and I explore the assumption that formal characteristics play a role in the aesthetic appreciation of novels. In

  16. Original Research

    African Journals Online (AJOL)

    2013-09-20

    Sep 20, 2013 ... Science, Technology and Arts Research Journal ... water quality parameters were analyzed using the membrane filtration method. Water ... is the first line of defense against water borne .... MATERIALS AND METHODS .... acid and distilled water. ... supply and sanitation laboratory for microbiological water ...

  17. Original Research

    African Journals Online (AJOL)

    2012-12-29

    Dec 29, 2012 ... and Anna C. Treydte1. 1 Agroecology in the Tropics ... Post Box No: 05, Ethiopia. 3 Adami Tulu Agricultural Research Centre, Ziway, Post Box No: 35, Ethiopia .... meat as food resource, oxen for draught power and equines for ...

  18. Original Research

    African Journals Online (AJOL)

    2013-12-27

    Dec 27, 2013 ... performance of the synthesizer was evaluated using accuracy as ... further research in the area, especially with the aim of developing a full- ... information and knowledge on a long term-basis and ... morphological processing systems such as morphological .... can combine to form variants of words.

  19. Original Research

    African Journals Online (AJOL)

    home

    2014-08-21

    Aug 21, 2014 ... Science, Technology and Arts Research Journal. Sci. Technol. ..... from poor to wealthier, in which 7(5.8%) farmers were poor ... type/cultivar of mango grown by small holder farmers was ... mango farm land witnessed, for first time this insect pest ..... Ethiopia to East Wollega, Guto Gida district, Loko village.

  20. Research medicine

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Highlights of the research effort during 1978 and 1979 include the development and use of a 280-crystal position tomograph; use of 11 C-labeled methionine in studies of heart metabolism and brain metabolism in humans; and studies of the megakaryocytic cell system

  1. Space research

    International Nuclear Information System (INIS)

    Tempelmayer, A.

    2000-01-01

    Space research in Austria began since 1969 and has its roots in Graz. An overview of the projects performed by Austrian organizations such as local network interconnection via satellites systems, MIGMAS (Microanalysis station), ALP-SAT (Autonomous Libration Point-Satellite), MIDAS (Micro-imaging dust analysis system), among others are described. (nevyjel)

  2. Research Article

    Indian Academy of Sciences (India)

    a

    research has found hundreds of genes encoding miRNAs in animals. .... By means of RNA-seq of sheep embryo pituitary gland (PG_E) and adult pituitary gland (PG_A), ... including Gap junction, Amoebiasis, Inflammatory bowel disease (IBD), ...

  3. Original Research

    African Journals Online (AJOL)

    Science, Technology and Arts Research Journal. July-Sep 2012, 1(3): 08-16 ... Revised :25-09-2012. Accepted :28-09- ..... vegetables, leaves, nuts, seeds, barks, roots and in other parts. ... antioxidant capacities of human plasma and natural compounds ... membrane lipid peroxidation and as peroxyl radical scavengers.

  4. Research Article

    African Journals Online (AJOL)

    2018-01-01

    Jan 1, 2018 ... ferrocene derivatives and potentially all analogous organometallic compounds. The results confirm the utility of use of square wave voltammetry techniques for measuring octanol-water partition coefficients of ferrocene derivatives. 5. ACKNOWLEDGEMENT. This research was financed by the laboratory of ...

  5. Research Article

    African Journals Online (AJOL)

    1 janv. 2016 ... Keywords: thermal energy; solar collector plane; air; simulation; outlet temperature. Author Correspondence, e-mail: ghodbanemokhtar39@yahoo.com doi: http://dx.doi.org/10.4314/jfas.v8i1.3. Journal of Fundamental and Applied Sciences. ISSN 1112-9867. Available online at http://www.jfas.info. Research ...

  6. Original Research

    African Journals Online (AJOL)

    2012-02-18

    Feb 18, 2012 ... Science, Technology and Arts Research Journal. Jan-March 2012, 1(1): ... simultaneously, this paper presents a novel iris recognition method based on the natural-open eyes. ... information, length information, width information of texture, the neighbouring ... Non-contacting biometrics is the inevitable trend.

  7. Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.

    2010-01-01

    This column features summaries of research articles from 3 recent crisis management publications. The first, "School Shootings and Counselor Leadership: Four Lessons from the Field" summarized by Kristi Fenning, was conducted as the result of the increased demand for trained crisis personnel on school campuses. Survey participants were…

  8. Population Research.

    Science.gov (United States)

    National Inst. of Child Health and Human Development (NIH), Bethesda, MD.

    The scope of population research as carried on by the National Institute of Child Health and Human Development (NICHD) is set forth in this booklet. Population problems of the world, United States, and the individual are considered along with international population policies based on voluntary family planning programs. NICHD goals for biological…

  9. Quantitative research

    DEFF Research Database (Denmark)

    Wigram, Anthony Lewis

    2003-01-01

    possible and desirable. It is not just a type of research done in a laboratory, or by PhD students. Some for of reliable measurement can be applied to many clinical situationsto evaluate the effects of therapy over time, or the difference between clients who receive therapy and those who don't. Evaluating...

  10. Energy research

    International Nuclear Information System (INIS)

    1979-03-01

    Status reports are given for the Danish Trade Ministry's energy research projects on uranium prospecting and extraction, oil and gas recovery, underground storage of district heating, electrochemical energy storage systems, wind mills, coal deposits, coal cambustion, energy consumption in buildings, solar heat, biogas, compost heat. (B.P.)

  11. Original Research

    African Journals Online (AJOL)

    home

    2014-12-19

    Dec 19, 2014 ... Science, Technology and Arts Research Journal ... The Relationship between Students' Perceived EFL Classroom Climate and ... classroom climate and their achievement in English language. .... learning. Furthermore, the finding may give teacher ..... effects on mathematics achievement of fourth-grade.

  12. Original Research

    African Journals Online (AJOL)

    2013-09-24

    Sep 24, 2013 ... the observers' lacks of visual research skills, they pay an equal attention to physical and social environment even in the absence of social activity facts in the photos. I argued that students used their mental image and memories of the urban space in commentaries about each photos. Besides, they used ...

  13. Multiskill Research.

    Science.gov (United States)

    Porter, Alan L.; Rossini, Frederick A.

    1986-01-01

    Crossdisciplinary research plays a major role in addressing any problems of intellectual and societal importance. A framework to characterize such projects that replices "discipline" by "intellectual skills" is described. This framework is then applied to the study of 40 National Science Foundation-sponsored projects. (JN)

  14. Research supervision

    African Journals Online (AJOL)

    Bachelor of Nursing: Advanced Practice (BNAP) degree, and 44.6% (n=25) had an Honours degree in nursing. The sociodemographic characteristics of the sample are given in Table 1. Research supervisor skills. One of the areas explored in this study is the students' perception of their supervisors' skills and knowledge of ...

  15. Research Article

    African Journals Online (AJOL)

    2016-06-18

    Jun 18, 2016 ... ficulties for researchers for finding proper information and ... hese systems present a personalized proposal to users who seek to .... In a survey of recommender services regarding digital library by [17], they mentioned some ... extracted topics based on the relationship between the paper's title, frequent ...

  16. Research Paper:

    African Journals Online (AJOL)

    Shanu

    2014-01-08

    Jan 8, 2014 ... Forty years in capsaicin research for sensory pharmacology and physiology. Neuropeptides 38:377-384. Thomas E (2002). Tissue culture studies in Arachis hypogea L. and. Vignaunguiculata (L.) Walp. for micropropagation and cell line selection for amino acid overproduction, Ph.D. Thesis, University of.

  17. Dialogue Research

    DEFF Research Database (Denmark)

    Duelund, Peter

    1991-01-01

    Departing from Anthony Giddens´s theory of structuration and the concept double hermeneutics and Jürgen Habermas´s Theory of Communicative Actions the article specifies theories and methods af dialogue as method in the humanities and social sciences. The article concludes by pointing at dialogues...... as a new theoretical, methodological and empirical research concept i an society where the traditional planning instruments have failed....

  18. RESEARCH COMMUNITIES

    Directory of Open Access Journals (Sweden)

    HUGO ESCOBAR-MELO

    2006-05-01

    Full Text Available This article constitutes an anthology of the research in the Department of Psychology of the UniversidadJaveriana and it takes as point of consultations the book Saber, sujeto y sociedad: Una década de investigación enPsicología published in the year 2006 by the Editorial Pontificia Universidad Javeriana as a collective work;it shows the research itinerary of the groups and authors which have worked in multiple problematicnucleus like the affective bonds in terms of emotional security and care, the psychological welfare as axleof the psychology of the health, the meanings and bonds to build cultures of peace, the public opinionthat mobilizes different senses in the world, the culture of the transport, the subjetivation and the speechthat mean to the work, the experimented body in the woman, the kidnapping and their ghost of thedeath, the family as a person networks linked by the language, person, relationships and psychic operation,quality of life, numeric thought, experimental psychology and cognitive neuropsycology.Without a doubt all these problematic nucleus seemingly diverse but crossed by the significance andsignificant implication, they have conformed a true disciplinary intersection, to the style of the geometric,convergent and strong cobwebs of the spiders. It also includes the present anthology, the basic principlesof a research culture and their most visible production in the Universitas Psychologica magazine.

  19. Federal research

    International Nuclear Information System (INIS)

    1991-04-01

    This book reviews the status of the Department of Energy's (DOE) Superconducting Super Collider (SSC), which will be located 30 miles south of Dallas, Texas. The SSC will be the world's largest high energy particle accelerator a research tool used by physicists to seek fundamental knowledge about energy and matter. DOE recently estimated that the SSC will cost $8.2 billion (in current-year dollars). This report provides information on the instability in tenure of DOE and SSC Laboratory project management, uncertainties related to the SSC site geology, uncertainties and risks with magnet development and production, and Texas' proposed contribution to the project's costs

  20. Researcher Women

    OpenAIRE

    Katalin Lipták

    2016-01-01

    I think that the equal opportunity and the underprivileged marginal labour-market layers’ significance play an important role in the economics of our days, so the women’s labour-market participation. Analysing the Hungarian data lines, we can see that the women’s labour-market participation significantly lags behind the men’s. I wish to prove with a questionnaire survey that in the North-Hungarian region the women’s labour-market situation and the career opportunities of the researcher women ...

  1. Researching experiences

    DEFF Research Database (Denmark)

    Gjedde, Lisa; Ingemann, Bruno

    In the beginning was - not the word - but the experience. This phenomenological approach provides the basis for this book, which focuses on how a person-in-situation experiences and constructs meaning from a variety of cultural visual events. This book presents video-based processual methods......, dialogue, moods, values and narratives have been investigated qualitatively with more than sixty informants in a range of projects. The processual methodological insights are put into a theoretical perspective and also presented as pragmatic dilemmas. Researching Experiences is relevant not only...

  2. Researcher Women

    Directory of Open Access Journals (Sweden)

    Katalin Lipták

    2016-12-01

    Full Text Available I think that the equal opportunity and the underprivileged marginal labour-market layers’ significance play an important role in the economics of our days, so the women’s labour-market participation. Analysing the Hungarian data lines, we can see that the women’s labour-market participation significantly lags behind the men’s. I wish to prove with a questionnaire survey that in the North-Hungarian region the women’s labour-market situation and the career opportunities of the researcher women lags behind the men’s slightly. Based on my research, beyond the women’s traditional home tasks have appeared the claims for work derives from the employment, so the double burden is put into practice, too. we can explain with the difficulties of the compatibility of childbearing and the work, the undertaking extra limited tasks of the workplace, providing extra performance which is sensible for the women, that in the North-Hungarian region the female career path move more slowly than the men’s.

  3. Speech Research

    Science.gov (United States)

    Several articles addressing topics in speech research are presented. The topics include: exploring the functional significance of physiological tremor: A biospectroscopic approach; differences between experienced and inexperienced listeners to deaf speech; a language-oriented view of reading and its disabilities; Phonetic factors in letter detection; categorical perception; Short-term recall by deaf signers of American sign language; a common basis for auditory sensory storage in perception and immediate memory; phonological awareness and verbal short-term memory; initiation versus execution time during manual and oral counting by stutterers; trading relations in the perception of speech by five-year-old children; the role of the strap muscles in pitch lowering; phonetic validation of distinctive features; consonants and syllable boundaires; and vowel information in postvocalic frictions.

  4. Types of Cancer Research

    Science.gov (United States)

    An infographic from the National Cancer Institute (NCI) describing the four broad categories of cancer research: basic research, clinical research, population-based research, and translational research.

  5. Novel research

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Author Robert Harris and film director Paul Greengrass visited CERN on 26 April, passing by SM18 as well as the CCC and the ATLAS control room.   Film director Paul Greengrass (left) and author Robert Harris (right). Author Robert Harris and film director Paul Greengrass visited CERN on 26 April as part of their preliminary research on an idea that Harris has for a book, which Greengrass might turn into a film. One of the characters would be a theoretical physicist from CERN – but to say more than that might give away the story! There is definite irony in the fact that their visit was delayed for a week by the ash from the Icelandic volcanic eruption. Harris is well known for several historical novels, including ‘Pompeii’, which tells the story of a fictional hydraulic engineer at the time of the eruption of Mount Vesuvius in 79 AD. His latest book, ‘The Ghost’, became a film directed by Roman Polanski, while the latest film from Greengrass is &a...

  6. Research Results

    Science.gov (United States)

    2012-01-01

    In situ Oxidation Study of Pt (110) and Its Interaction with CO Chinese Scientists Published a Paper on Prevention of Drug Craving and Relapse by Memory Retrieval-extinction Procedure in Science Series Papers Published in Energy Policy: Modeling Energy Use of China's Road Transport and Policy Evaluation Breakthrough in the Ambient Catalytic Destruction of Formaldehyde Novel Findings for High Altitude Adaptation from the Yak Genome Binary Colloidal Structures Assembled through Ising Interactions Reemergence of superconductivity at 48K in Compressed Iron Selenide Based Superconductors Nucleosomes Suppress Spontaneous Mutations Base-Specifically in Eukaryotes Single-Chain Fragmented Antibodies Guided SiRNA Delivery in Breast Cancer Does Yeast Suicide? China Scientists Developed Important Methodologies for Spatiotemporal Detecting and Manipulating of Cellular Activities Scorpions Inspire Chinese Scientists in Making Bionic Non-eroding Surfaces for Machinery Research on Phylogenetic Placement of Borthwickia and Description of a New Family of Angiosperms, Borthwickiaceae Plasmoid Ejection and Secondary Current Sheet Generation from Magnetic Reconnection in Laser-plasma Interaction Cotton Bollworm Adapts to Bt Cotton via Diverse Mutations A Histone Acetyltransferase Regulates Active DNA Demethylation in Arabidopsis

  7. Research Report

    Science.gov (United States)

    Dawes, Lyn

    2004-06-01

    This paper examines what is important about talk between learners during school science and, having identified this, suggests how we can ensure that what we consider important happens. By looking at the interaction between teachers and learners talking about science, it is possible to indicate ways in which learners can be helped to continue this learning conversation with one another when teacher support is withdrawn. Strategies for teaching and learning are examined. The paper reports on the findings of a research project designed to teach children how to negotiate their ideas about science concepts through rational dialogue. Children's development of scientific concepts in classrooms is undertaken through structured activity and mediated through oral language. Children must move forward simultaneously in their use of specialized vocabulary and in their understanding of current scientific explanations, models and ideas. New language and new ways of using language are learned by doing, which means for children, primarily speaking and listening. Children's understanding of science can benefit from teaching them to understand that spoken language is a powerful tool for thinking together.

  8. Research medicine

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    In Section I of this annual report, a brief summary of work is presented by the Research Medicine Group. The major emphasis has been the study of the blood system in man with a special emphasis on the examination of platelet abnormalities in human disease. New programs of major importance include the study of aging or dementia of the Alzheimer's type. A differential diagnosis technique has been perfected using positron emission tomography. Studies on the biochemical basis of schizophrenia have proceeded using radioisotope studies which image physiological and biochemical processes. In the investigation of atherosclerosis, techniques have been developed to measure blood perfusion of the heart muscle by labelling platelets and lipoproteins. Progress is reported in a new program which uses NMR for both imaging and spectroscopic studies in humans. The group has determined through an epidemiological study that bubble chamber and cyclotron workers who have been exposed to high electromagnetic fields for two decades have no significant increases in the prevalence of 21 diseases as compared with controls

  9. Research medicine

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    A major effort of this program is in the field of quantitative radionuclide imaging. Four approaches to noninvasive evaluation of human biochemical and physiological states are used: positron tomography for three-dimensional quantitative imaging; computerized whole-body scanning of isotope distribution; expired air analysis of 14 CO 2 from the metabolism of injected pharmaceuticals; and whole-body counting. This program is closely associated with the development of instrumentation and radiopharmaceuticals for radionuclide studies, and the investigative studies using them. Its major emphasis is to apply the efforts of new instrumentation and radiopharmaceuticals to medical problems such as brain and heart blood flow and metabolism resulting from various disease and environmental conditions. Kinetic analyses are made based on the conservation-of-mass equation and precise information of the sequential tissue concentrations by three-dimensional imaging. The technology being developed embodies the concept of in vivo biochemistry of amino acids, fatty acids, and glucose. This group continues its research effort in the hematology area. Currently studies of the megakaryocytic cell system are being carried out in an effort to understand platelet turnover and how the blood platelet count is regulated. This is important not only in a broad spectrum of blood disorders, but also in the evaluation of toxic environmental pollutants

  10. Airborne ocean water lidar (OWL) real time processor (RTP)

    Science.gov (United States)

    Hryszko, M.

    1995-03-01

    The Hyperflo Real Time Processor (RTP) was developed by Pacific-Sierra Research Corporation as a part of the Naval Air Warfare Center's Ocean Water Lidar (OWL) system. The RTP was used for real time support of open ocean field tests at Barbers Point, Hawaii, in March 1993 (EMERALD I field test), and Jacksonville, Florida, in July 1994 (EMERALD I field test). This report describes the system configuration, and accomplishments associated with the preparation and execution of these exercises. This document is intended to supplement the overall test reports and provide insight into the development and use of the PTP. A secondary objective is to provide basic information on the capabilities, versatility and expandability of the Hyperflo RTP for possible future projects. It is assumed herein that the reader has knowledge of the OWL system, field test operations, general lidar processing methods, and basic computer architecture.

  11. Future Research

    International Nuclear Information System (INIS)

    Beebe, G.W.; Hamilton, H.B.

    1975-01-01

    Much remains to be learned from continued monitoring of the medical experience of the Hiroshima and Nagasaki A-bomb survivors. Many effects are so small, or have such long latent periods, that there is not even now a complete catalogue of effects visible in this large population. There is as yet no evidence of a mutagenic effect, but biochemical and cytogenetic approaches now offer powerful tools for a final effort to derive information that may set limits on the size of the doubling dose for mutations in man. The list of specific neoplasms induced by the whole-body exposure to the A-bomb radiation remains incomplete, and the quantitative dose-response aspects of established carcinogenic effects remains to be worked out in relation to time, host factors, linear energy transfer (LET) characteristics of radiation, and risk factors other than radiation. The dose-response estimates must be made, where possible, in terms of tissue dose. If there is to be any definitive test of the hypothesis of radiation accelerated aging in man, it will doubtless come from observations on the A-bomb survivors. The experience of the A-bomb survivors can make no direct contribution to knowledge of dose rate, and is much too small to provide direct information in the region of low dose. Nevertheless, as better knowledge of mechanisms of radiation damage and repair accumulates from laboratory experimental programs, this unique human experience will be of increasing value to radiation biology. Continued monitoring of the health and medical experience of the A-bomb survivors will depend on the voluntary cooperation of the subjects and their families, and on the interest of the physicians in the community. Present indications are that the research would gain from a closer association with medical care and health maintenance programs. (auth.)

  12. Research Productivity and Academics' Conceptions of Research

    Science.gov (United States)

    Brew, Angela; Boud, David; Namgung, Sang Un; Lucas, Lisa; Crawford, Karin

    2016-01-01

    This paper asks the question: do people with different levels of research productivity and identification as a researcher think of research differently? It discusses a study that differentiated levels of research productivity among English and Australian academics working in research-intensive environments in three broad discipline areas: science,…

  13. Using action research for complex research initiatives

    CSIR Research Space (South Africa)

    Greeff, M

    2009-12-01

    Full Text Available the research process of such a complex research initiative. Action research is one research method that lends itself to these complex projects. The paper uses the Ability Based Technology Interventions (AbTi) research project as a case study to analyse...

  14. Cancer Research UK | IDRC - International Development Research ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cancer Research UK. Cancer Research UK. https://www.cancerresearchuk.org/. The Economics of Tobacco Control Research Initiative. The Economics of Tobacco Control Research Initiative funds innovative fiscal policy research supporting tobacco control in low and middle-income countries. View more. The Economics ...

  15. Research Staff | Chemistry and Nanoscience Research | NREL

    Science.gov (United States)

    Research Staff Research Staff Research staff members in NREL's Chemistry and Nanoscience Center are Electrochemical Engineering and Materials Chemistry. For lead researcher contacts, see our research areas. For our : Chemistry and Nanoscience In addition to his position at NREL, Dr. van de Lagemaat is also a fellow of the

  16. Wood Protection Research Council: Research Priorities 2013

    Science.gov (United States)

    Carol A Clausen; Frederick Green III; Grant T. Kirker; Stan T. Lebow

    2014-01-01

    This report summarizes presentations and comments from the inaugural Wood Protection Research Council meeting. Research needs for the wood protection industry were identified and prioritized. Methods for successfully addressing research needs were discussed by industry, academia, and association representatives.

  17. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library Resources Research Resources Clinical Research Resources Safety, Regulation and Guidance More » Quick Links PubMed Stem ...

  18. Research Program Overview

    Science.gov (United States)

    PEER logo Pacific Earthquake Engineering Research Center home about peer news events research products laboratories publications nisee b.i.p. members education FAQs links research Research Program Overview Tall Buildings Initiative Transportation Research Program Lifelines Program Concrete Grand

  19. Current Research Studies

    Science.gov (United States)

    ... Success Home > Explore Research > Current Research Studies Current Research Studies Email Print + Share The Crohn’s & Colitis Foundation ... conducted online. Learn more about IBD Partners. Clinical Research Alliance The Clinical Research Alliance is a network ...

  20. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library Resources Research Resources Clinical Research Resources Safety, Regulation ...

  1. FNS Research Corner: Summary of Research

    Science.gov (United States)

    Gola, Alice Ann H.; Burdg, Jinee

    2018-01-01

    The FNS Research Corner provides a continuing series to summarize recently completed and current research conducted by the U.S. Department of Agriculture's Food and Nutrition Service (FNS) in the area of child nutrition. Summaries of recently completed research projects and in-progress research are provided in this article.

  2. Research tools | IDRC - International Development Research Centre

    International Development Research Centre (IDRC) Digital Library (Canada)

    Through training materials and guides, we aim to build skills and knowledge to enhance the quality of development research. We also offer free access to our database of funded research projects, known as IDRIS+, and our digital library. Our research tools include. Guide to research databases at IDRC: How to access and ...

  3. Changing Research Practices and Research Infrastructure Development

    Science.gov (United States)

    Houghton, John W.

    2005-01-01

    This paper examines changing research practices in the digital environment and draws out implications for the development of research infrastructure. Reviews of the literature, quantitative indicators of research activities and our own field research in Australia suggest that there is a new mode of knowledge production emerging, changing research…

  4. Researching Research: Mathematics Education in the Political

    Science.gov (United States)

    Pais, Alexandre; Valero, Paola

    2012-01-01

    We discuss contemporary theories in mathematics education in order to do research on research. Our strategy consists of analysing discursively and ideologically recent key publications addressing the role of theory in mathematics education research. We examine how the field fabricates its object of research by deploying Foucault's notion of…

  5. Mixed methods research.

    Science.gov (United States)

    Halcomb, Elizabeth; Hickman, Louise

    2015-04-08

    Mixed methods research involves the use of qualitative and quantitative data in a single research project. It represents an alternative methodological approach, combining qualitative and quantitative research approaches, which enables nurse researchers to explore complex phenomena in detail. This article provides a practical overview of mixed methods research and its application in nursing, to guide the novice researcher considering a mixed methods research project.

  6. African Primary Care Research: Participatory action research

    OpenAIRE

    Mash, Bob

    2014-01-01

    This article is part of the series on African primary care research and focuses on participatory action research. The article gives an overview of the emancipatory-critical research paradigm, the key characteristics and different types of participatory action research. Following this it describes in detail the methodological issues involved in professional participatory action research and running a cooperative inquiry group. The article is intended to help students with writing their researc...

  7. Researching collaboratively: implications for qualitative research and researchers.

    Science.gov (United States)

    Cheek, Julianne

    2008-11-01

    Often discussions about collaborative research, and collaboration generally, begin at the point of how to collaborate, who to collaborate with, and what to collaborate about. Rarely do they include equally important questions of why we are having discussions about collaboration, where such an impetus and emphasis is coming from, and how it connects to the contemporary political research context. In a recent editorial in Qualitative Health Research, Janice Morse highlighted the need for reflection about collaboration. This article responds to that call, providing reflections on collaboration, the imperative to collaborate, and what this all might mean for both qualitative research and qualitative researchers. I hope to stimulate new points of departure for thinking and action shaping collaborative research endeavors without-and just as crucially, within-qualitative research.

  8. Design Research between Design and Research

    DEFF Research Database (Denmark)

    Steinø, Nicolai; Markussen, Thomas

    2011-01-01

    The discourse on architecture and design research in Denmark in the past thirty years has been stuck in a unproductive dichotomy between research through design on the one hand and a phantom image of academic and theoretical, word-based research on the other. Advocates of the research through...... design strand have argued, that architecture and design research must follow an architecture and design methodology – designing – and be communicated by means of architecture and design media – images and artefacts. Essentially, this view sees no difference between architecture and design research...... and practice, as expressed in the notion of research as ‘artistic innovation work’. On the other hand, the pressure to expand research in architecture and design has seen a movement towards adopting traditional research paradigms from the technical and social sciences and humanities. For many architects...

  9. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Lines Health Services Locator HealthCare.gov NIH Clinical Research Trials and You Talking to Your Doctor Science ... More » Quick Links NIH News in Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives ...

  10. Research Staff | Buildings | NREL

    Science.gov (United States)

    Research Staff Research Staff Photo of Roderick Jackson Roderick Jackson Laboratory Program Manager -related research at NREL. He works closely with senior laboratory management to set the strategic agenda for NREL's buildings portfolio, including all research, development, and market implementation

  11. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in ... can. The genetic methods for all sorts of medical genetic disorders have been refined over the past ...

  12. 1991 research and technology

    Science.gov (United States)

    1992-01-01

    Selected research and technology activities at Ames Research Center, including the Moffett Field site and the Dryden Flight Research Facility, are summarized. These activities exemplify the Center's varied and productive research efforts for 1991.

  13. Agricultural Research Service

    Science.gov (United States)

    ... Menu United States Department of Agriculture Agricultural Research Service Research Research Home National Programs Research Projects Scientific Manuscripts International Programs Scientific Software/Models Databases and Datasets Office of Scientific Quality ...

  14. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research Trials and You Talking to Your Doctor Science Education Resources Community Resources Clear Health A–Z ... Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics ...

  15. The modern research environment

    DEFF Research Database (Denmark)

    Topsøe, Flemming

    1993-01-01

    Information Technology, research environment, structured documents, networked information retrieval......Information Technology, research environment, structured documents, networked information retrieval...

  16. From Action Research to Practice Research

    Directory of Open Access Journals (Sweden)

    Goran Goldkuhl

    2012-04-01

    Full Text Available Action research (AR has gained more acceptance as an approach to qualitative research in information systems (IS. The complexities of organisational and technical change makes this approach a suitable one in IS research. There are, however, still some controversies and confusions about the relation between “action” and “research”. The many types of AR and similar approaches (not labelled as AR that have emerged demands further conceptual clarification of AR. A conceptual inquiry of AR, presented in the paper, has led to the identification of several unresolved issues concerning intervention research like AR. An alternative research approach is presented: practice research. This research approach is well founded in pragmatism and it builds on the two premises: 1 to contribute to general practice through abstract and useful knowledge and 2 to study the empirical field as interconnected practices. Several important concepts of practice research are described as: local practice contribution vs. general practice contribution; theorizing vs. situational inquiry. Practice research is seen as a broader notion encompassing AR and other research approaches as e.g. design research and evaluation research. Two case examples of practice research are briefly presented and compared: one AR-based study in the social welfare sector and one evaluation study of a taxation e-service.

  17. Research Fellows | NREL

    Science.gov (United States)

    Research Fellows Research Fellows Our research fellows advise on the strategic direction of science and technology research at NREL and ensure our work meets the highest standards for quality and objectivity. Find all research staff by visiting our various research program areas. Photo of Mowafak Al

  18. What is Research

    Science.gov (United States)

    2016-10-27

    Service Nursing Research Program (TSNRP): Defense Medical Research & Development Program (DMROP): NIH: Congressionally Directed Medical Research Program...measuring outcomes. · setting/environment that aenerated It. Techniques Quantitative Research PICOT, ARCC, PARIHS, POCA, OMAIC, Six Sigma, and...SGVU SUBJECT: Professional Presentation Approval 3 NOV 2016 1. Your paper, entitled What is Research ? presented at/published to Resident Research

  19. Research and technology, 1993

    Science.gov (United States)

    1994-01-01

    Selected research and technology activities at Ames Research Center, including the Moffett Field site and the Dryden Flight Research Facility, are summarized. These activities exemplify the center's varied and productive research efforts for 1993. This year's report presents some of the challenging work recently accomplished in the areas of aerospace systems, flight operations and research, aerophysics, and space research.

  20. The School Research Lead

    Science.gov (United States)

    Bennett, Tom

    2015-01-01

    The researchED movement has generated a new debate about the role of research in schools. Of course there have always been teachers interested in undertaking research and applying the research findings of others. However, involvement in research has tended to be the personal enthusiasm of the individual teacher rather than a coordinated whole…

  1. Case Study Research Methodology in Nursing Research.

    Science.gov (United States)

    Cope, Diane G

    2015-11-01

    Through data collection methods using a holistic approach that focuses on variables in a natural setting, qualitative research methods seek to understand participants' perceptions and interpretations. Common qualitative research methods include ethnography, phenomenology, grounded theory, and historic research. Another type of methodology that has a similar qualitative approach is case study research, which seeks to understand a phenomenon or case from multiple perspectives within a given real-world context.

  2. Environmental research - ecological research. Annual report 1996

    International Nuclear Information System (INIS)

    1997-01-01

    In the annual report 1996 of the Federal Ministry of Research and Technology, the points of emphasis of the ecological research programme and their financing are discussed. The individual projects in the following subject areas are described in detail: urban-industrial landscapes, forests, agricultural landscapes, river and lake landscapes, other ecosystems and landscapes, terrestrial ecosystem research, environmental pollution and human health and cross-sectional activities in ecological research. (vhe) [de

  3. Research Through Design & Research Through Education

    NARCIS (Netherlands)

    Eggink, Wouter; Mulder-Nijkamp, Maaike; Bohemia, Erik; Kovacevic, Ahmed; Buck, Lyndon; Tollestrup, Christian; Eriksen, Kaare; Ovesen, Nis

    2016-01-01

    The very definition of a university is a place where research and education are intertwined. When there is no research, a university will look like a place for vocational training, and when there are no students to teach, the university is no more than a research institution. This convention of

  4. NIH Research: Advances in Parkinson's Disease Research

    Science.gov (United States)

    ... of this page please turn JavaScript on. NIH Research: Advances in Parkinson's Disease Research Past Issues / Winter 2014 Table of Contents Story ... Photo courtesy of NIH Advances in Parkinson's Disease Research Story Landis, Ph.D., has been Director of ...

  5. Research award: Collaborative Adaptation Research Initiative in ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2017-09-06

    Sep 6, 2017 ... The Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA) builds resilience in these hot spots by supporting collaborative research on climate change adaptation to inform adaptation policy and practice. Specifically, CARIAA supports four consortia that research geographic and social ...

  6. Research partnerships between business researchers and industry

    NARCIS (Netherlands)

    Zalewska-Kurek, Katarzyna; Janßen, Björn; Harms, Rainer

    2016-01-01

    We study the strategic behaviour of management researchers when establishing research partnerships with industry. To this end we developed a framework distinguishing ‘strategic planned’ and ‘opportunity-driven’ behaviour in the process of establishing and managing research partnerships. We also

  7. Rocky Mountain Research Station: 2010 Research Accomplishments

    Science.gov (United States)

    Rick Fletcher

    2010-01-01

    The Rocky Mountain Research Station is one of seven regional units that make up the USDA Forest Service Research and Development organization ­ the most extensive natural resources research organization in the world. We maintain 12 field laboratories throughout a 12-state territory encompassing the Great Basin, Southwest, Rocky Mountains, and parts of the Great Plains...

  8. Research Supervision: The Research Management Matrix

    Science.gov (United States)

    Maxwell, T. W.; Smyth, Robyn

    2010-01-01

    We briefly make a case for re-conceptualising research project supervision/advising as the consideration of three inter-related areas: the learning and teaching process; developing the student; and producing the research project/outcome as a social practice. We use this as our theoretical base for an heuristic tool, "the research management…

  9. Research Award: Advisory Committee on Research Ethics

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC CRDI

    ACRE seeks a Research Awardee to study research ethics in an ... The following topics are examples of issues that could be ... advance their career goals, and recognize the dual nature of the position—applied research activity and general ...

  10. Mixed methods research in music therapy research.

    Science.gov (United States)

    Bradt, Joke; Burns, Debra S; Creswell, John W

    2013-01-01

    Music therapists have an ethical and professional responsibility to provide the highest quality care possible to their patients. Much of the time, high quality care is guided by evidence-based practice standards that integrate the most current, available research in making decisions. Accordingly, music therapists need research that integrates multiple ways of knowing and forms of evidence. Mixed methods research holds great promise for facilitating such integration. At this time, there have not been any methodological articles published on mixed methods research in music therapy. The purpose of this article is to introduce mixed methods research as an approach to address research questions relevant to music therapy practice. This article describes the core characteristics of mixed methods research, considers paradigmatic issues related to this research approach, articulates major challenges in conducting mixed methods research, illustrates four basic designs, and provides criteria for evaluating the quality of mixed methods articles using examples of mixed methods research from the music therapy literature. Mixed methods research offers unique opportunities for strengthening the evidence base in music therapy. Recommendations are provided to ensure rigorous implementation of this research approach.

  11. Fuel Chemistry Research | Transportation Research | NREL

    Science.gov (United States)

    Fuel Chemistry Research Fuel Chemistry Research Photo of a hand holding a beaker containing a clear oils. Photo by Dennis Schroeder, NREL NREL's fuel chemistry research explores how biofuels, advanced , emissions control catalysts, and infrastructure materials. Results from NREL's fuel chemistry studies feed

  12. Researcher-researched relationship in qualitative research: Shifts in positions and researcher vulnerability.

    Science.gov (United States)

    Råheim, Målfrid; Magnussen, Liv Heide; Sekse, Ragnhild Johanne Tveit; Lunde, Åshild; Jacobsen, Torild; Blystad, Astrid

    2016-01-01

    The researcher role is highly debated in qualitative research. This article concerns the researcher-researched relationship. A group of health science researchers anchored in various qualitative research traditions gathered in reflective group discussions over a period of two years. Efforts to establish an anti-authoritarian relationship between researcher and researched, negotiation of who actually "rules" the research agenda, and experiences of shifts in "inferior" and "superior" knowledge positions emerged as central and intertwined themes throughout the discussions. The dual role as both insider and outsider, characteristic of qualitative approaches, seemed to lead to power relations and researcher vulnerability which manifested in tangible ways. Shifting positions and vulnerability surfaced in various ways in the projects. They nonetheless indicated a number of similar experiences which can shed light on the researcher-researched relationship. These issues could benefit from further discussion in the qualitative health research literature.

  13. Research Facilities | Wind | NREL

    Science.gov (United States)

    Research Facilities Research Facilities NREL's state-of-the-art wind research facilities at the Research Facilities Photo of five men in hard hards observing the end of a turbine blade while it's being tested. Structural Research Facilities A photo of two people silhouetted against a computer simulation of

  14. Nuclear research reactors

    International Nuclear Information System (INIS)

    1985-01-01

    It's presented data about nuclear research reactors in the world, retrieved from the Sien (Nuclear and Energetic Information System) data bank. The information are organized in table forms as follows: research reactors by countries; research reactors by type; research reactors by fuel and research reactors by purpose. (E.G.) [pt

  15. Action and Interactiv research

    DEFF Research Database (Denmark)

    Nielsen, Kurt Aagaard; Svensson, Lennart

    The text is written as a first version of editors introduction to a book about action research/interactive research in Nordic countries. You can read abouttrends and contradictions in the history of action research.The authors question the trends and demands a more explicit critical approach...... to actual action research/interactive research....

  16. Nuclear energy related research

    International Nuclear Information System (INIS)

    Mattila, L.; Vanttola, T.

    1991-10-01

    The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1991. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects

  17. Nuclear energy related research

    International Nuclear Information System (INIS)

    Rintamaa, R.

    1992-05-01

    The annual Research Programme Plan describes publicly funded nuclear energy related research to be carried out mainly at the Technical Research Centre of Finland (VTT) in 1992. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Other research institutes, utilities and industry also contribute to many projects

  18. From Research Assistant to Professional Research Assistance: Research Consulting as a Form of Research Practice

    Directory of Open Access Journals (Sweden)

    Dawn E. Pollon

    2013-01-01

    Full Text Available Research assistantships have long been viewed as an extension of the formal education process, a form of apprenticeship, and a pathway into the professional practice of research in institutional settings. However, there are other contexts in which researchers practice research. This self-study documents the formative role research assistantships played in the authors’ development as professional research consultants. Four professional research consultants who held research assistant positions during their master’s and doctoral studies describe the contributions of their research assistantship experiences to the advancement of their knowledge, skills, and passion for research and subsequently to their career decisions. Professional research consulting is identified as a natural extension of research assistant roles and a potential career path. The article enhances current understandings about the ways research assistantships contribute to the development of researchers, and specifically to the development of professional research consultants. The analysis will be of interest to students contemplating entering into research assistantships, current research assistants, current research assistant supervisors, academic staff looking to improve their research productivity, and department chairs.

  19. Research Methodology in Global Strategy Research

    DEFF Research Database (Denmark)

    Cuervo-Cazurra, Alvaro; Mudambi, Ram; Pedersen, Torben

    2017-01-01

    We review advances in research methodology used in global strategy research and provide suggestions on how researchers can improve their analyses and arguments. Methodological advances in the extraction of information, such as computer-aided text analysis, and in the analysis of datasets......, such as differences-in-differences and propensity score matching, have helped deal with challenges (e.g., endogeneity and causality) that bedeviled earlier studies and resulted in conflicting findings. These methodological advances need to be considered as tools that complement theoretical arguments and well......-explained logics and mechanisms so that researchers can provide better and more relevant recommendations to managers designing the global strategies of their organizations....

  20. Research Article Special Issue

    African Journals Online (AJOL)

    2017-08-08

    Aug 8, 2017 ... development of research and innovative activities at Russian ... curriculum integration of scientific knowledge in project research .... settle research tasks, use of heuristic approaches, idea generation methods; development of.

  1. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Research & Training Medical Research Initiatives Science Highlights Science ... Drayna, Ph.D., an intramural researcher at the National Institute on Deafness and Other Communication Disorders at the NIH, ...

  2. Research Article Special Issue

    African Journals Online (AJOL)

    pc

    2018-02-24

    Feb 24, 2018 ... 1Research Coordinator, Research Management Office, Office of the Vice President for. Research, Extension .... Wet Average Budget. Cash costs ... 10. Table 2. Inventory of Non - Cash Costs Incurred in Rice Production. Dry.

  3. Researcher Story: Stuttering

    Science.gov (United States)

    ... Have a Question In the News Researcher Story: Stuttering In a 2010 movie, The King’s Speech, many ... effects of the disorder. How Do Researchers Study Stuttering? Video of How Do Researchers Study Stuttering? A ...

  4. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Have a Question In the News Researcher Story: Stuttering In a 2010 movie, The King’s Speech, many ... effects of the disorder. How Do Researchers Study Stuttering? Video of How Do Researchers Study Stuttering? A ...

  5. ERC Vision & Research

    Science.gov (United States)

    SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing (ERC ) ** Bringing Sustainability to Semiconductor Manufacturing ** A multi-university research center leading the way to environmentally friendly semiconductor manufacturing, sponsored by the Semiconductor Research

  6. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... NIH…Turning Discovery Into Health ® Impact of NIH Research Science, Health, and Public Trust You are here Home » Health Information » NIH Clinical Research Trials and You NIH Clinical Research Trials and ...

  7. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Trials and You Talking to Your Doctor Science Education Resources Community Resources Clear Health A–Z Publications ... Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library ...

  8. National Privacy Research Strategy

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — On July 1, NITRD released the National Privacy Research Strategy. Research agencies across government participated in the development of the strategy, reviewing...

  9. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Toolkits Grants & Funding Grants Home Page Funding Forms Library Due Dates How to Apply About Grants Policy & ... Education Research in NIH Labs & Clinics Training Opportunities Library Resources Research Resources Clinical Research Resources Safety, Regulation ...

  10. Prevention Research Matters

    Centers for Disease Control (CDC) Podcasts

    Prevention Research Matters is a series of one-on-one interviews with researchers from 26 university prevention research centers across the country. Their work focuses on preventing and controlling chronic diseases like obesity, cancer, and heart disease.

  11. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... If You Have a Question In the News Researcher Story: Stuttering In a 2010 movie, The King’s ... mitigate the effects of the disorder. How Do Researchers Study Stuttering? Video of How Do Researchers Study ...

  12. Fuel safety research 1999

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-07-01

    In April 1999, the Fuel Safety Research Laboratory was newly established as a result of reorganization of the Nuclear Safety Research Center, JAERI. The laboratory was organized by combining three laboratories, the Reactivity Accident Laboratory, the Fuel Reliability Laboratory, and a part of the Sever Accident Research Laboratory. Consequently, the Fuel Safety Research Laboratory is now in charge of all the fuel safety research in JAERI. Various types of experimental and analytical researches are conducted in the laboratory by using the unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and hot cells in JAERI. The laboratory consists of five research groups corresponding to each research fields. They are; (a) Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). (b) Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). (c) Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). (d) Research group of fuel behavior analysis (FEMAXI group). (e) Research group of FP release/transport behavior from irradiated fuel (VEGA group). This report summarizes the outline of research activities and major outcomes of the research executed in 1999 in the Fuel Safety Research Laboratory. (author)

  13. High Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL's High-Pressure Combustion Research Facility in Morgantown, WV, researchers can investigate new high-pressure, high-temperature hydrogen turbine combustion...

  14. Research Award: Global Health Research Iniave

    International Development Research Centre (IDRC) Digital Library (Canada)

    Corey Piccioni

    2013-08-07

    Aug 7, 2013 ... IDRC is one of the world's leaders in generang new knowledge to meet global challenges. We offer a number of research awards providing a unique opportunity to enhance research skills and gain a fresh perspecve on crucial development issues. These one‐year, paid, in‐house programs of training and ...

  15. Teaching Qualitative Research to Practitioner-Researchers

    Science.gov (United States)

    Cox, Rebecca D.

    2012-01-01

    Practitioner-researchers are well-positioned to apply qualitative methods to the study of significant problems of educational practice. However, while learning the skills of qualitative inquiry, practitioners may be compelled by forces outside of qualitative research classrooms to think quantitatively. In this article, the author considers two…

  16. Researching as an Enactivist Mathematics Education Researcher

    Science.gov (United States)

    Brown, Laurinda

    2015-01-01

    This paper focusses on how researching is done through reflections about, or at a meta-level to, the practice over time of an enactivist mathematics education researcher. How are the key concepts of enactivist theory ("ZDM Mathematics Education," doi: 10.1007/s11858-014-0634-7, 2015) applied? This paper begins by giving an…

  17. Researchers' intuitions about power in psychological research

    NARCIS (Netherlands)

    Bakker, M.; Hartgerink, C. H. J.; Wicherts, J. M.; Van Der Maas, H. L. J.

    2016-01-01

    Many psychology studies are statistically underpowered. In part, this may be because many researchers rely on intuition, rules of thumb, and prior practice (along with practical considerations) to determine the number of subjects to test. In Study 1, we surveyed 291 published research psychologists

  18. Storytelling as Research/Research as Storytelling

    Science.gov (United States)

    Lewis, Patrick J.

    2011-01-01

    If story is central to human meaning why, in the research world, is there not more storytelling? Walter Benjamin (1973) noted that, "a story is different. It does not expend itself. It preserves and concentrates its strength and is capable of releasing it even after a long time" (p. 90). How might research not expend itself, but preserve and…

  19. Research Associate | Center for Cancer Research

    Science.gov (United States)

    PROGRAM DESCRIPTION The Basic Science Program (BSP) pursues independent, multidisciplinary research in basic and applied molecular biology, immunology, retrovirology, cancer biology, and human genetics. Research efforts and support are an integral part of the Center for Cancer Research (CCR) at the Frederick National Laboratory for Cancer Research (FNLCR). KEY ROLES/RESPONSIBILITIES - Research Associate III Dr. Zbigniew Dauter is the head investigator of the Synchrotron Radiation Research Section (SRRS) of CCR’s Macromolecular Crystallography Laboratory. The Synchrotron Radiation Research Section is located at Argonne National Laboratory, Argonne, Illinois; this is the site of the largest U.S. synchrotron facility. The SRRS uses X-ray diffraction technique to solve crystal structures of various proteins and nucleic acids of biological and medical relevance. The section is also specializing in analyzing crystal structures at extremely high resolution and accuracy and in developing methods of effective diffraction data collection and in using weak anomalous dispersion effects to solve structures of macromolecules. The areas of expertise are: Structural and molecular biology Macromolecular crystallography Diffraction data collection Dr. Dauter requires research support in these areas, and the individual will engage in the purification and preparation of samples, crystallize proteins using various techniques, and derivatize them with heavy atoms/anomalous scatterers, and establish conditions for cryogenic freezing. Individual will also participate in diffraction data collection at the Advanced Photon Source. In addition, the candidate will perform spectroscopic and chromatographic analyses of protein and nucleic acid samples in the context of their purity, oligomeric state and photophysical properties.

  20. Research Librarian | IDRC - International Development Research ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Job Summary The Research Librarian is a key member of a team responsible for the delivery of comprehensive research information services which contribute strategic value to the work of clients. Intermediated search services at the expert level, the development and delivery of orientations, training/coaching, ...

  1. Stunningly bright optical emission

    Science.gov (United States)

    Heinke, Craig O.

    2017-12-01

    The detection of bright, rapid optical pulsations from pulsar PSR J1023+0038 have provided a surprise for researchers working on neutron stars. This discovery poses more questions than it answers and will spur on future work and instrumentation.

  2. Ames Research Center Research and Technology 2000

    Science.gov (United States)

    2002-01-01

    This report highlights the challenging work accomplished during fiscal year 2000 by Ames research scientists,engineers, and technologists. It discusses research and technologies that enable the Information Age, that expand the frontiers of knowledge for aeronautics and space, and that help to maintain U.S. leadership in aeronautics and space research and technology development. The accomplishments are grouped into four categories based on four of NASA's Strategic Enterprises: Aerospace Technology, Space Science, Biological and Physical Research, and Earth Science. The primary purpose of this report is to communicate knowledge-to inform our stakeholders, customer, and partners, and the people of the United States about the scope and diversity of Ames' mission,the nature of Ames' research and technolog) activities,and the stimulating challenges ahead. The accomplishments cited illustrate the contributions that Ames is willing to improve the quality of life for our citizens and the economic position of the United States in the world marketplace.

  3. Research and technology, 1991. Langley Research Center

    Science.gov (United States)

    1992-01-01

    The mission of the NASA Langley Research Center is to increase the knowledge and capability of the United States in a full range of aeronautics disciplines and in selected space disciplines. This mission will be accomplished by performing innovative research relevant to national needs and Agency goals, transferring technology to users in a timely manner, and providing development support to other United States Government agencies, industry, and other NASA centers. Highlights are given of the major accomplishments and applications that have been made during the past year. The highlights illustrate both the broad range of the research and technology (R&T) activities at NASA Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research.

  4. From nuclear research to multidisciplinary research

    International Nuclear Information System (INIS)

    Theenhaus, R.; Baurmann, K.W.

    1996-01-01

    Forty years ago, the North Rhine-Westphalian State Government founded the then Juelich Nuclear Research Center. After a growth period of the reactor engineering program until 1980, claiming a share of 42% of R and D resources, that share declined continuously to a present level of 8%. This development is an expression of the activities successfully completed in the past, of progress achieved in industrial reactor development, but also of the fact that the high temperature reactor, which had been run successfully for twenty years, failed as a technical scale THTR-300 version. The Center has reorientated its line of research in a process of structural reshuffle beginning some fifteen years ago and still going on. Information technology, materials research, life sciences, environmental research, and energy technology have become main activities of equal weight. Activities specific to nuclear reactors have been incorporated in this new line of work as nuclear safety research and work on safe repository storage. (orig.) [de

  5. Teaching to Enhance Research

    Science.gov (United States)

    Harland, Tony

    2016-01-01

    In this paper, I present a conceptual argument for "teaching-led research" in which university lecturers construct courses that directly and positively influence their research, while at the same time, safeguard and enhance the student experience. A research-pedagogy for higher education considers the link between teaching and research,…

  6. School-Based Research

    Science.gov (United States)

    Glennon, Catherine; Hinton, Christina; Callahan, Thomas; Fischer, Kurt W.

    2013-01-01

    In the field of medicine, research and practice are joined in teaching hospitals. In these institutions, researchers work alongside doctors to incorporate recent advances in medical research into practice and track results. There is a growing movement in the field of education to create analogous institutions in education called research schools.…

  7. IDRC Doctoral Research Awards

    International Development Research Centre (IDRC) Digital Library (Canada)

    test

    1) Research Proposal. Proposals must be 20-25 pages, double-spaced, in 12 point font (not inclusive of bibliography) and address ALL of the following items, presented in separate headings: • Abstract of research proposal. (max. 250 words). • Literature Review. • Research question(s). • Research objective. • Methodology.

  8. Research Staff | Wind | NREL

    Science.gov (United States)

    Research Staff Research Staff Learn more about the expertise and technical skills of the wind power research team and staff at NREL. Name Position Email Phone Anstedt, Sheri Professional III-Writer/Editor /Web Content Sheri.Anstedt@nrel.gov 303-275-3255 Baker, Donald Research Technician V-Electrical

  9. Solar Research | NREL

    Science.gov (United States)

    Research Photo of a city landscape with a sun in the background. Solar energy research at NREL includes photovoltaics, concentrating solar power, solar grid and systems integration, and market research and analysis. Photovoltaic Research Photo of a roof-mounted PV array on the NREL campus. NREL's

  10. Research in Mathematics Education

    Science.gov (United States)

    Schoenfeld, Alan H.

    2016-01-01

    As one of the three Rs, "'rithmetic" has always been central to education and education research. By virtue of that centrality, research in mathematics education has often reflected and at times led trends in education research. This chapter provides some deep background on epistemological and other issues that shape current research,…

  11. Research Staff | Bioenergy | NREL

    Science.gov (United States)

    Research Staff Research Staff Photo of Adam Bratis, Ph.D. Adam Bratis Associate Lab Director-Bio research to accomplish the objectives of the Department of Energy's Bioenergy Technologies Office, and to serve as a spokesperson for the bioenergy research effort at NREL, both internally and externally. This

  12. Nuclear energy related research

    International Nuclear Information System (INIS)

    Salminen, Pertti

    1989-03-01

    This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1989. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself

  13. Stimulating translational research

    DEFF Research Database (Denmark)

    Bentires-Alj, Mohamed; Rajan, Abinaya; van Harten, Wim

    2015-01-01

    Translational research leaves no-one indifferent and everyone expects a particular benefit. We as EU-LIFE (www.eu-life.eu), an alliance of 13 research institutes in European life sciences, would like to share our experience in an attempt to identify measures to promote translational research with...... without undermining basic exploratory research and academic freedom....

  14. Nuclear energy related research

    International Nuclear Information System (INIS)

    Salminen, P.; Mattila, L.

    1990-08-01

    The annual Research Programme Plan describes the publicly funded nuclear energy related research to be carried out at the Technical Research Centre of Finland (VTT) in 1990. The research is financed primarily by the Ministry of Trade and Industry (KTM), the Finnish Centre for Radiation and Nuclear Safety (STUK) and VTT itself. Utilities and industry also contribute to some projects

  15. Researching entrepreneurship with autoethnography

    DEFF Research Database (Denmark)

    Gottlieb, Frederik

    2015-01-01

    In this paper, the author presents a discussion of the implications and opportunities of researching with autoethnography, in an entrepreneurial context. The research is based on 2 narratives written on the account of the researchers deep involvement in a small startup company. The researcher rel...

  16. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Media Contacts Images and B-roll Events Social Media More » Quick Links NIH News in Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics Training Opportunities Library ...

  17. Research Methods Tutorial

    Science.gov (United States)

    Aguilera, Frank J.

    2015-01-01

    A guiding principle for conducting research in technology, science, and engineering, leading to innovation is based on our use of research methodology (both qualitative and qualitative). A brief review of research methodology will be presented with an overview of NASA process in developing aeronautics technologies and other things to consider in research including what is innovation.

  18. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... Resources Media Contacts Images and B-roll Events Social Media More » Quick Links NIH News in Health NIH Research Matters NIH Record Research & Training Medical Research Initiatives Science Highlights Science Education Research in NIH Labs & Clinics ...

  19. Nuclear energy related research

    International Nuclear Information System (INIS)

    Salminen, P.

    1988-02-01

    This annual Research Programme Plan covers the publicly funded nuclear energy related research planned to be carried out at the Technical Research Centre of Finland (VTT) in 1988. The research will be financed by the Ministry of Trade and Industry, the Finnish Centre for Radiation and Nuclear Safety, the Nordic Council of Ministers and VTT itself

  20. Qualitative Research in Psychology

    Directory of Open Access Journals (Sweden)

    Fattah Hanurawan

    2013-02-01

    Full Text Available Abstract:Qualitative  research  is  a  research  method    studying  subjective meaning of participant’s world about  an object researched. Steps of qualitative research  in  psychology  are:  researchers  select  research  topic,  researchers formulate  research  questions,  researchers  design  the  study,  researchers  collect data, researchers analyses  data,  researchers  generate  findings,  researchers validate findings, and researchers write research report. Some of the qualitative research  designs  are  grounded  research,  phenomenology  research,  case  study research,  and  ethnography  research.  In  some  situations,  researchers  often  meet questions  that  reach  beyond  the  prescription  of  the  APA  ethical  guidelines concerning  human  participants.  Researchers  of  qualitative  research  in psychology  can  generalize  their  research  findings  to  other  people,  times,  or treatments  to  the  degree  to  which  they  are  similar to  other  people,  times,  or treatments in the original research (naturalistic generalization. There are some strategies  for  expanding  qualitative  research  as  a research  approach  so  the methodology  can  be  accepted  as  one  significant  method  in  understanding psychological phenomena. Keywords:qualitative research, psychology.

  1. Improving University Research Value

    Directory of Open Access Journals (Sweden)

    Kelley O’Reilly

    2012-07-01

    Full Text Available This article investigates the current data management practices of university researchers at an Intermountain West land-grant research university in the United States. Key findings suggest that researchers are primarily focused on the collection and housing of research data. However, additional research value exists within the other life cycle stages for research data—specifically in the stages of delivery and maintenance. These stages are where most new demands and requirements exist for data management plans and policies that are conditional for external grant funding; therefore, these findings expose a “gap” in current research practice. These findings should be of interest to academics and practitioners alike as findings highlight key management gaps in the life cycle of research data. This study also suggests a course of action for academic institutions to coalesce campus-wide assets to assist researchers in improving research value.

  2. Succeeding with interactive research

    DEFF Research Database (Denmark)

    Krogh, Andreas Hagedorn; Nielsen, Morten Velsing

    2017-01-01

    the capacity for critique and ensuring that scientific standards are met. Based on our own experience and theories of interactive governance, network management and collaborative leadership, as well as on existing methodological literature, we provide guidance and suggest concrete tools and methods......Increasingly, social science research is carried out in collaboration with partners outside universities, yet research methodology is lacking on how to manoeuvre in a terrain where multiple actors set expectations for research. This article conceptualizes interactive research as research...

  3. Rigour in quantitative research.

    Science.gov (United States)

    Claydon, Leica Sarah

    2015-07-22

    This article which forms part of the research series addresses scientific rigour in quantitative research. It explores the basis and use of quantitative research and the nature of scientific rigour. It examines how the reader may determine whether quantitative research results are accurate, the questions that should be asked to determine accuracy and the checklists that may be used in this process. Quantitative research has advantages in nursing, since it can provide numerical data to help answer questions encountered in everyday practice.

  4. Research report 1994

    International Nuclear Information System (INIS)

    1994-01-01

    The Scottish Universities Research and Reactor Centre (SURRC) at East Kilbride provides research and teaching facilities associated with a research reactor for the Scottish Universities. The document contains details of current (1994) research programs. Research covers a broad range of subjects, often pursued with the collaboration of other institutions. A wide range of experimental facilities exists funded by a mixture of grants and commercial contracts. (UK)

  5. Succeeding with interactive research

    DEFF Research Database (Denmark)

    Krogh, Andreas Hagedorn; Nielsen, Morten Velsing

    2017-01-01

    Increasingly, social science research is carried out in collaboration with partners outside universities, yet research methodology is lacking on how to manoeuvre in a terrain where multiple actors set expectations for research. This article conceptualizes interactive research as research...... the capacity for critique and ensuring that scientific standards are met. Based on our own experience and theories of interactive governance, network management and collaborative leadership, as well as on existing methodological literature, we provide guidance and suggest concrete tools and methods...

  6. Research by design - a research strategy

    DEFF Research Database (Denmark)

    Hauberg, Jørgen

    2011-01-01

    Abstract The idea of an expressive component in research is important to the architectural industry. The expressive element - the possibility of expressing the qualitative aspects of the world and adding something new to the existing through experiments and proposals - is characteristic....... Research is ‘coloured’ by traditions and professions, and research in architecture should be coloured too, taking in consideration that the practise of architects stretch from natural science and sociology to art, and because the most important way in which the architect achieves new cognition is through...... for the field. All research environments, in the science tradition and in the humanities, have their characteristics. On the one hand, they live up to certain common scientific and methodological criteria - originality and transparency - on the other hand they have different practices, using different methods...

  7. Research by Design - a research strategy

    DEFF Research Database (Denmark)

    Hauberg, Jørgen

    2011-01-01

    Abstract The idea of an expressive component in research is important to the architectural industry. The expressive element - the possibility of expressing the qualitative aspects of the world and adding something new to the existing through experiments and proposals - is characteristic...... methods. Research is ‘coloured’ by traditions and professions, and research in architecture should be coloured too, taking into consideration that the practice of architects stretches from natural science and sociology to art and that the most important way in which the architect achieves new cognition...... for the field. All research environments, in the science tradition and in the humanities, have their characteristics. On the one hand, they live up to certain common scientific and methodological criteria - originality and transparency – and on the other hand, they have different practices, using different...

  8. Sandia National Laboratories: Research: Research Foundations: Nanodevices

    Science.gov (United States)

    Technology Partnerships Business, Industry, & Non-Profits Government Universities Center for Mexico Small Business Assistance Program Sandia Science & Technology Park Careers Community support for research; technology advancement and maturation; and small-lot, fast-turn prototyping Our

  9. Fuel safety research 2000

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    In April 1999, the Fuel Safety Research Laboratory was newly established as a part of reorganization of the Nuclear Safety Research Center, JAERI. The new laboratory was organized by combining three pre-existing laboratories, Reactivity Accident Laboratory, Fuel Reliability Laboratory, and a part of Severe Accident Research Laboratory. The Fuel Safety Research Laboratory becomes to be in charge of all fuel safety research in JAERI. Various experimental and analytical researches are conducted in the laboratory by using the unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and hot cells in JAERI. The laboratory consists of following five research groups corresponding to each research fields; (a) Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). (b) Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). (c) Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). (d) Research group of fuel behavior analysis (FEMAXI group). (e) Research group of FP release/transport behavior from irradiated fuel (VEGA group). The research activities in year 2000 produced many important data and information. They are, for example, failure of high burnup BWR fuel rod under RIA conditions, data on the behavior of hydrided Zircaloy cladding under LOCA conditions and FP release data from VEGA experiments at very high temperature/pressure condition. This report summarizes the outline of research activities and major outcomes of the research executed in 2000 in the Fuel Safety Research Laboratory. (author)

  10. The qualitative research proposal

    Directory of Open Access Journals (Sweden)

    H Klopper

    2008-09-01

    Full Text Available Qualitative research in the health sciences has had to overcome many prejudices and a number of misunderstandings, but today qualitative research is as acceptable as quantitative research designs and is widely funded and published. Writing the proposal of a qualitative study, however, can be a challenging feat, due to the emergent nature of the qualitative research design and the description of the methodology as a process. Even today, many sub-standard proposals at post-graduate evaluation committees and application proposals to be considered for funding are still seen. This problem has led the researcher to develop a framework to guide the qualitative researcher in writing the proposal of a qualitative study based on the following research questions: (i What is the process of writing a qualitative research proposal? and (ii What does the structure and layout of a qualitative proposal look like? The purpose of this article is to discuss the process of writing the qualitative research proposal, as well as describe the structure and layout of a qualitative research proposal. The process of writing a qualitative research proposal is discussed with regards to the most important questions that need to be answered in your research proposal with consideration of the guidelines of being practical, being persuasive, making broader links, aiming for crystal clarity and planning before you write. While the structure of the qualitative research proposal is discussed with regards to the key sections of the proposal, namely the cover page, abstract, introduction, review of the literature, research problem and research questions, research purpose and objectives, research paradigm, research design, research method, ethical considerations, dissemination plan, budget and appendices.

  11. Ageing of research reactors

    International Nuclear Information System (INIS)

    Ciocanescu, M.

    2001-01-01

    Historically, many of the research institutions were centred on a research reactor facility as main technological asset and major source of neutrons for research. Important achievements were made in time in these research institutions for development of nuclear materials technology and nuclear safety for nuclear energy. At present, ageing of nuclear research facilities among these research reactors and ageing of staff are considerable factors of reduction of competence in research centres. The safe way of mitigation of this trend deals with ageing management by so called, for power reactors, Plant Life Management and new investments in staff as investments in research, or in future resources of competence. A programmatic approach of ageing of research reactors in correlation with their actual and future utilisation, will be used as a basis for safety evaluation and future spending. (author)

  12. 'The research compass'

    DEFF Research Database (Denmark)

    Ringsted, Charlotte; Hodges, Brian; Scherpbier, Albert

    2011-01-01

    This AMEE Guide offers an introduction to research in medical education. It is intended for those who are contemplating conducting research in medical education but are new to the field. The Guide is structured around the process of transforming ideas and problems into researchable questions...... by the complexity of the field. Next is a section on how to move from an idea or problem to a research question by placing a concrete idea or problem within a conceptual, theoretical framework. The following sections are structured around an overview model of approaches to medical education research, 'The research......, choosing a research approach that is appropriate to the purpose of the study and considering the individual researcher's preferences and the contextual possibilities and constraints. The first section of the Guide addresses the rationale for research in medical education and some of the challenges posed...

  13. Qualitative research, tourism

    DEFF Research Database (Denmark)

    Ren, Carina Bregnholm

    2016-01-01

    of qualitative research has meant a need to question and redefine criteria and research standards otherwise used in tourism research, as qualitative approach does not (seek to) conform to ideals such as truth, objectivity, and validity retrieved in the positivist sciences. In order to develop new ways by which......, the understanding of qualitative research as unable (or rather unwilling) to deliver the types of outcome which “explain and predict” tourism, has impacted upon its ability to gain general acceptance. Only slowly has tourism research made room for the changes in social and cultural sciences, which since the 1960s......Qualitative research, tourism Qualitative research refers to research applying a range of qualitative methods in order to inductively explore, interpret, and understand a given field or object under study. Qualitative research in tourism takes its inspiration primarily from the cultural and social...

  14. Responsible conduct of research

    CERN Document Server

    Shamoo, Adil E

    2015-01-01

    Since the early 2000s, the field of Responsible Conduct of Research has become widely recognized as essential to scientific education, investigation, and training. At present, research institutions with public funding are expected to have some minimal training and education in RCR for their graduate students, fellows and trainees. These institutions also are expected to have a system in place for investigating and reporting misconduct in research or violations of regulations in research with human subjects, or in their applications to federal agencies for funding. Public scrutiny of the conduct of scientific researchers remains high. Media reports of misconduct scandals, biased research, violations of human research ethics rules, and moral controversies in research occur on a weekly basis. Since the 2009 publication of the 2nd edition of Shamoo and Resnik's Responsible Conduct of Research, there has been a vast expansion in the information, knowledge, methods, and diagnosis of problems related to RCR and the ...

  15. Translational Educational Research

    Science.gov (United States)

    Issenberg, S. Barry; Cohen, Elaine R.; Barsuk, Jeffrey H.; Wayne, Diane B.

    2012-01-01

    Medical education research contributes to translational science (TS) when its outcomes not only impact educational settings, but also downstream results, including better patient-care practices and improved patient outcomes. Simulation-based medical education (SBME) has demonstrated its role in achieving such distal results. Effective TS also encompasses implementation science, the science of health-care delivery. Educational, clinical, quality, and safety goals can only be achieved by thematic, sustained, and cumulative research programs, not isolated studies. Components of an SBME TS research program include motivated learners, curriculum grounded in evidence-based learning theory, educational resources, evaluation of downstream results, a productive research team, rigorous research methods, research resources, and health-care system acceptance and implementation. National research priorities are served from translational educational research. National funding priorities should endorse the contribution and value of translational education research. PMID:23138127

  16. Fuel safety research 2001

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-11-01

    The Fuel Safety Research Laboratory is in charge of research activity which covers almost research items related to fuel safety of water reactor in JAERI. Various types of experimental and analytical researches are being conducted by using some unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and the Reactor Fuel Examination Facility (RFEF) of JAERI. The research to confirm the safety of high burn-up fuel and MOX fuel under accident conditions is the most important item among them. The laboratory consists of following five research groups corresponding to each research fields; Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). Research group of fuel behavior analysis (FEMAXI group). Research group of radionuclides release and transport behavior from irradiated fuel under severe accident conditions (VEGA group). The research conducted in the year 2001 produced many important data and information. They are, for example, the fuel behavior data under BWR power oscillation conditions in the NSRR, the data on failure-bearing capability of hydrided cladding under LOCA conditions and the FP release data at very high temperature in steam which simulate the reactor core condition during severe accidents. This report summarizes the outline of research activities and major outcomes of the research executed in 2001 in the Fuel Safety Research Laboratory. (author)

  17. Executable research compendia in geoscience research infrastructures

    Science.gov (United States)

    Nüst, Daniel

    2017-04-01

    From generation through analysis and collaboration to communication, scientific research requires the right tools. Scientists create their own software using third party libraries and platforms. Cloud computing, Open Science, public data infrastructures, and Open Source enable scientists with unprecedented opportunites, nowadays often in a field "Computational X" (e.g. computational seismology) or X-informatics (e.g. geoinformatics) [0]. This increases complexity and generates more innovation, e.g. Environmental Research Infrastructures (environmental RIs [1]). Researchers in Computational X write their software relying on both source code (e.g. from https://github.com) and binary libraries (e.g. from package managers such as APT, https://wiki.debian.org/Apt, or CRAN, https://cran.r-project.org/). They download data from domain specific (cf. https://re3data.org) or generic (e.g. https://zenodo.org) data repositories, and deploy computations remotely (e.g. European Open Science Cloud). The results themselves are archived, given persistent identifiers, connected to other works (e.g. using https://orcid.org/), and listed in metadata catalogues. A single researcher, intentionally or not, interacts with all sub-systems of RIs: data acquisition, data access, data processing, data curation, and community support [3]. To preserve computational research [3] proposes the Executable Research Compendium (ERC), a container format closing the gap of dependency preservation by encapsulating the runtime environment. ERCs and RIs can be integrated for different uses: (i) Coherence: ERC services validate completeness, integrity and results (ii) Metadata: ERCs connect the different parts of a piece of research and faciliate discovery (iii) Exchange and Preservation: ERC as usable building blocks are the shared and archived entity (iv) Self-consistency: ERCs remove dependence on ephemeral sources (v) Execution: ERC services create and execute a packaged analysis but integrate with

  18. Advancing Ethical Neuroscience Research.

    Science.gov (United States)

    Borah, B Rashmi; Strand, Nicolle K; Chillag, Kata L

    2016-12-01

    As neuroscience research advances, researchers, clinicians, and other stakeholders will face a host of ethical challenges. The Presidential Commission for the Study of Bioethical Issues (Bioethics Commission) has published two reports that provide recommendations on how to advance research endeavors ethically. The commission addressed, among other issues, how to prioritize different types of neuroscience research and how to include research participants who have impaired consent capacity. The Bioethics Commission's recommendations provide a foundation for ethical guidelines as neuroscience research advances and progresses. © 2016 American Medical Association. All Rights Reserved.

  19. Consumer Behavior Research Methods

    DEFF Research Database (Denmark)

    Chrysochou, Polymeros

    2017-01-01

    This chapter starts by distinguishing consumer behavior research methods based on the type of data used, being either secondary or primary. Most consumer behavior research studies phenomena that require researchers to enter the field and collect data on their own, and therefore the chapter...... emphasizes the discussion of primary research methods. Based on the nature of the data primary research methods are further distinguished into qualitative and quantitative. The chapter describes the most important and popular qualitative and quantitative methods. It concludes with an overall evaluation...... of the methods and how to improve quality in consumer behavior research methods....

  20. Swedish Energy Research 2009

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    Swedish Energy Research 2009 provides a brief, easily accessible overview of the Swedish energy research programme. The aims of the programme are to create knowledge and skills, as needed in order to commercialise the results and contribute to development of the energy system. Much of the work is carried out through about 40 research programmes in six thematic areas: energy system analysis, the building as an energy system, the transport sector, energy-intensive industries, biomass in energy systems and the power system. Swedish Energy Research 2009 describes the overall direction of research, with examples of current research, and results to date within various thematic areas and highlights

  1. Research in business ethics

    Directory of Open Access Journals (Sweden)

    G.J. Rossouw

    2001-08-01

    Full Text Available Research in business ethics is vital for the expansion and credibility of this fairly recent academic field. This article argues that there are three factors that are crucially important for research in business ethics. They are (a the ontological assumptions that research in this field is premised upon, (b the choice of research strategies and methodologies and (c the role of theory in research practice. Each of these three factors is explored and pitfalls relating to each of them are identified. The article also suggests guidelines for dealing with each of these factors in business ethics research.

  2. Fostering Integrity in Research

    Science.gov (United States)

    McNutt, M. K.

    2017-12-01

    The responsible conduct of research requires that all involved in the research enterprise - researchers, sponsors, reviewers, publishers, and communicators - adhere to a set of integrity principles to protect the public's investment. Given the increasing complexity and globalization of the research enterprise, the National Academies recently re-examined and updated its integrity recommendations for researchers in the report Fostering Integrity in Research, with sponsorship from the National Science Foundation. Major departures from the previous recommendations 25-years earlier are the recognition that practices that were previously classified as merely questionable are indeed detrimental to the responsible conduct of research. Furthermore, the report concludes that there has been insufficient effort to respond to the threats that lapses in research integrity pose to the quality of research products and the reputation of researchers as deserving of the public trust. It recommends the creation of an independent, non-profit entity dedicated to promoting research integrity by serving as a resource and clearing house for expertise, advice, materials, and best practices on fostering research integrity and responding to allegations of research misconduct.

  3. Economics of fusion research

    International Nuclear Information System (INIS)

    1977-01-01

    This report provides the results of a study of methods of economic analysis applied to the evaluation of fusion research. The study recognizes that a hierarchy of economic analyses of research programs exists: standard benefit-cost analysis, expected value of R and D information, and expected utility analysis. It is shown that standard benefit-cost analysis, as commonly applied to research programs, is inadequate for the evaluation of a high technology research effort such as fusion research. A methodology for performing an expected value analysis is developed and demonstrated and an overview of an approach to perform an expected utility analysis of fusion research is presented. In addition, a potential benefit of fusion research, not previously identified, is discussed and rough estimates of its magnitude are presented. This benefit deals with the effect of a fusion research program on optimal fossil fuel consumption patterns. The results of this study indicate that it is both appropriate and possible to perform an expected value analysis of fusion research in order to assess the economics of a fusion research program. The results indicate further that the major area of benefits of fusion research is likely due to the impact of a fusion research program on optimal fossil fuel consumption patterns and it is recommended that this benefit be included in future assessments of fusion research economics

  4. Economics of fusion research

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1977-10-15

    This report provides the results of a study of methods of economic analysis applied to the evaluation of fusion research. The study recognizes that a hierarchy of economic analyses of research programs exists: standard benefit-cost analysis, expected value of R and D information, and expected utility analysis. It is shown that standard benefit-cost analysis, as commonly applied to research programs, is inadequate for the evaluation of a high technology research effort such as fusion research. A methodology for performing an expected value analysis is developed and demonstrated and an overview of an approach to perform an expected utility analysis of fusion research is presented. In addition, a potential benefit of fusion research, not previously identified, is discussed and rough estimates of its magnitude are presented. This benefit deals with the effect of a fusion research program on optimal fossil fuel consumption patterns. The results of this study indicate that it is both appropriate and possible to perform an expected value analysis of fusion research in order to assess the economics of a fusion research program. The results indicate further that the major area of benefits of fusion research is likely due to the impact of a fusion research program on optimal fossil fuel consumption patterns and it is recommended that this benefit be included in future assessments of fusion research economics.

  5. Fair ranking of researchers and research teams.

    Science.gov (United States)

    Vavryčuk, Václav

    2018-01-01

    The main drawback of ranking of researchers by the number of papers, citations or by the Hirsch index is ignoring the problem of distributing authorship among authors in multi-author publications. So far, the single-author or multi-author publications contribute to the publication record of a researcher equally. This full counting scheme is apparently unfair and causes unjust disproportions, in particular, if ranked researchers have distinctly different collaboration profiles. These disproportions are removed by less common fractional or authorship-weighted counting schemes, which can distribute the authorship credit more properly and suppress a tendency to unjustified inflation of co-authors. The urgent need of widely adopting a fair ranking scheme in practise is exemplified by analysing citation profiles of several highly-cited astronomers and astrophysicists. While the full counting scheme often leads to completely incorrect and misleading ranking, the fractional or authorship-weighted schemes are more accurate and applicable to ranking of researchers as well as research teams. In addition, they suppress differences in ranking among scientific disciplines. These more appropriate schemes should urgently be adopted by scientific publication databases as the Web of Science (Thomson Reuters) or the Scopus (Elsevier).

  6. The Singapore research story

    CERN Document Server

    Teck Seng, Low; Thampuran, Raj

    2016-01-01

    Ever since Singapore became independent in 1965, its leaders have invested tremendous efforts and resources to develop its economy in order to create jobs for its people and to support national development. This book describes the challenging journey of Singapore in developing a knowledge-based economy driven by research and innovation and the roles played by research institutes, universities, research manpower and appropriate collaboration between research institutes and industry. The book traces the foundations of Singapore's research story from the time of its independence in 1965 to the present day. Through interviews with the key players and research into the records, the establishment of the key institutes and the roles of a global cast of researchers, scientists and engineers in setting up the R&D infrastructure are outlined. The impact that the concerted efforts of the last 25 years to build up a credible and world-class research capability in Singapore is discussed, as are the tremendous challeng...

  7. Research Article Special Issue

    African Journals Online (AJOL)

    pc

    2017-11-24

    Nov 24, 2017 ... academic studies of the research problem or in foreign language ... with the culture, ethnology and history of the Turkish people, economic and physical ... Thus, the relevance of the research topic is determined by shortage of ...

  8. Research Award: Networked Economies

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    2015-08-06

    year, paid, ... the areas of democracy, human rights and economic growth. ... Networked Economies is seeking a Research Award Recipient to explore research questions ... such as engineering or computer/information science;.

  9. Tehran Nuclear Research Center

    International Nuclear Information System (INIS)

    Taherzadeh, M.

    1977-01-01

    The Tehran Nuclear Research Center was formerly managed by the University of Tehran. This Center, after its transformation to the AEOI, has now become a focal point for basic research in the area of Nuclear Energy in Iran

  10. A Virtual Research Partner

    National Research Council Canada - National Science Library

    Cowie, Jim; Guerrero, Felicia

    2006-01-01

    .... The goal was to investigate the feasibility of creating a software agent that would be able to interact with researchers and provide them with support at a level equivalent to a human research partner...

  11. Research Programs & Initiatives

    Science.gov (United States)

    CGH develops international initiatives and collaborates with other NCI divisions, NCI-designated Cancer Centers, and other countries to support cancer control planning, encourage capacity building, and support cancer research and research networks.

  12. Ice Engineering Research Area

    Data.gov (United States)

    Federal Laboratory Consortium — Refrigerated Physical Modeling of Waterways in a Controlled EnvironmentThe Research Area in the Ice Engineering Facility at the Cold Regions Research and Engineering...

  13. Researcher Story: Stuttering

    Medline Plus

    Full Text Available ... research volunteers. If you stutter or have a family member who stutters, you could be eligible to ... Researchers Study Stuttering? A large portion of the family clustering of stuttering is explained by genes and ...

  14. Contemporary danish landscape research

    DEFF Research Database (Denmark)

    Vejre, H.; Brandt, J.

    2004-01-01

    Danish landscape research blossomed during the 1990’ies thanks to several transdisciplinary research programmes involving several institutions. The main themes of the programmes encompassed Landscape change, landscape and biological diversity, nature and landscape management, use and monitoring...

  15. Researcher Interview: Tom Hudson

    Science.gov (United States)

    Tom Hudson, M.D., President and Scientific Director of the Ontario Institute for Cancer Research, describes the International Cancer Genome Consortium (ICGC), which brings together cancer genomic data and research from across the world.

  16. Photochemistry research at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, C.E.; Carlson, C.E. [National Renewable Energy Laboratory, Golden, CO (United States)

    1996-09-01

    Photochemistry research team at NREL conducts research and development work in all R&D areas, basic, applied, demonstration and transfer to commercialization. Basic research includes core PCO R&D and catalysts work as well as conducting research into new photochemistry areas such as photoinduced adsorption and high temperature solar PCO. Applied research work consists of remediation of chloroethylenes in gas phase, gas phase solar photoreactor development, and application research including indoor air quality, hybrid biological/PCO processes and more. We are demonstrating the PCO treatment technology in the gas phase with SEMATECH through CRADA work and remediation of organics in aqueous phase through the Solarchem Environmental Systems. We are working with IT through a CRADA to transfer the PCO gas phase remediation technology to IT to commercialize this promising -technology. Photochemistry research conducted at NREL spans the R&D spectrum from basic research through technology demonstration with the goal of technology commercialization.

  17. Improving Practice through Research.

    Science.gov (United States)

    Rose, Terry L.

    1989-01-01

    The article discusses the need for communication of research findings involving exceptional individuals, the need for resolution of the research-practice dichotomy, and the types of papers which will appear in the new column. (JDD)

  18. Lymphatic Education & Research Network

    Science.gov (United States)

    Lymphatic Education & Research Network Donate Now Become a Supporting Member X Living with LYMPHEDEMA AND Lymphatic Disease FAQs About ... December 8, 2017 11.08.2017 The Lymphatic Education & Research Network… Read More > ASRM LE&RN Combined ...

  19. Environmental Toxicology Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Fully-equipped facilities for environmental toxicology researchThe Environmental Toxicology Research Facility (ETRF) located in Vicksburg, MS provides over 8,200 ft...

  20. Researching Identity and Interculturality

    DEFF Research Database (Denmark)

    Lønsmann, Dorte

    2016-01-01

    Review of: Researching Identity and Interculturality / by F. Dervin and K. Risager (eds.). Routledge 2015, 245 pp.......Review of: Researching Identity and Interculturality / by F. Dervin and K. Risager (eds.). Routledge 2015, 245 pp....