116 research outputs found

    Linking the X-ray timing and spectral properties of the glitching AXP 1RXS J170849-400910

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    Previous studies of the X-ray flux and spectral properties of 1RXS J170849-400910 showed hints of a possible correlation with the spin glitches that occurred in 1999 and 2001. However, due to the sparseness of spectral measurements and the paucity of detected glitches no firm conclusion could be drawn. We retrieved and analysed archival XTE pointings of 1RXS J170849-400910 covering the time interval between January 2003 and June 2006 and carried out a detailed timing analysis by means of phase fitting techniques. We detected two relatively large glitches Delta nu / nu of 1.2 and 2.1 10^-6 occurred in January and June 2005. Interestingly, the occurrence times of these glitches are in agreement with the predictions made in our previous studies. This finding strongly suggests a connection between the flux, spectral and timing properties of 1RXS J170849-400910.Comment: Submitted to A&A, 4 pages; results presented at the INT meeting "The Neutron Star Crust and Surface: Observations and Models" on June 27; referee comments adde

    The Vehicle, Fall 2000

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    Vol. 42, No. 1 Table of Contents I Never Even Knew the Room NumberJeremy Hartzellpage 5 Charcoal Sketches of the MoonAlex Cardonapage 6 A Street, a Cat, the Sky, my Shoes, my Feet, TonightJanet Windeguthpage 7 Mainlining AmoreShanna Hullpage 9 Forest ChoirJeremy Hartzellpage 10 Ritual Timepiece ConfigurationsStella Linkpage 11 Carpe DiemRobb Dunnpage 12 Lost in AmericaTodd Beardpage 13 NeurastheniaBen Erwinpage 14 CowardVeronica Espinosapage 15 UntitledCarrie Smiglapage 16 When I Close My EyesJeremy Hartzellpage 17 Brigstaff ButterflyShanna Hullpage 18 Mice in the MotelRobb Dunnpage 19 The EscapeShanna Hullpage 21 RunningNicholas Janquartpage 29https://thekeep.eiu.edu/vehicle/1073/thumbnail.jp

    The Vehicle, Fall 2000

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    Vol. 42, No. 1 Table of Contents I Never Even Knew the Room NumberJeremy Hartzellpage 5 Charcoal Sketches of the MoonAlex Cardonapage 6 A Street, a Cat, the Sky, my Shoes, my Feet, TonightJanet Windeguthpage 7 Mainlining AmoreShanna Hullpage 9 Forest ChoirJeremy Hartzellpage 10 Ritual Timepiece ConfigurationsStella Linkpage 11 Carpe DiemRobb Dunnpage 12 Lost in AmericaTodd Beardpage 13 NeurastheniaBen Erwinpage 14 CowardVeronica Espinosapage 15 UntitledCarrie Smiglapage 16 When I Close My EyesJeremy Hartzellpage 17 Brigstaff ButterflyShanna Hullpage 18 Mice in the MotelRobb Dunnpage 19 The EscapeShanna Hullpage 21 RunningNicholas Janquartpage 29https://thekeep.eiu.edu/vehicle/1073/thumbnail.jp

    Gravitational wave emission from a magnetically deformed non-barotropic neutron star

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    A strong candidate for a source of gravitational waves is a highly magnetised, rapidly rotating neutron star (magnetar) deformed by internal magnetic stresses. We calculate the mass quadrupole moment by perturbing a zeroth-order hydrostatic equilibrium by an axisymmetric magnetic field with a \emph{linked poloidal-toroidal structure}. In this work, we do \emph{not} require the model star to obey a barotropic equation of state (as a realistic neutron star is not barotropic), allowing us to explore the hydromagnetic equilibria with fewer constraints. We derive the relation between the ratio of poloidal-to-total field energy Λ\Lambda and ellipticity ϵ\epsilon and briefly compare our results to those obtained using the barotropic assumption. Then, we present some examples of how our results can be applied to astrophysical contexts. First, we show how our formulae, in conjunction with current gravitational wave (non-)detections of the Crab pulsar and the Cassiopeia A central compact object (Cas A CCO), can be used to constrain the strength of the internal toroidal fields of those objects. We find that, for the Crab pulsar (whose canonical equatorial dipole field strength, inferred from spin down, is 4×1084\times 10^8 T) to emit detectable gravitational radiation, the neutron star must have a strong toroidal field component, with maximum internal toroidal field strength Btm=7×1012B_{\mathrm{tm}}=7\times 10^{12} T; for gravitational waves to be detected from the Cas A CCO at 300 Hz, Btm1013B_{\mathrm{tm}}\sim 10^{13} T, whereas detection at 100 Hz would require Btm1014B_{\mathrm{tm}}\sim 10^{14} T. Using our results, we also show how the gravitational wave signal emitted by a magnetar immediately after its birth (assuming it is born rapidly rotating, with Λ0.2\Lambda\lesssim 0.2) makes such a newborn magnetar a stronger candidate for gravitational wave detection than, for example, an SGR giant flare.Comment: 15 pages, 8 figures, 2 table

    Structure, Deformations and Gravitational Wave Emission of Magnetars

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    Neutron stars can have, in some phases of their life, extremely strong magnetic fields, up to 10^15-10^16 G. These objects, named magnetars, could be powerful sources of gravitational waves, since their magnetic field could determine large deformations. We discuss the structure of the magnetic field of magnetars, and the deformation induced by this field. Finally, we discuss the perspective of detection of the gravitational waves emitted by these stars.Comment: 11 pages, 2 figures, prepared for 19th International Conference on General Relativity and Gravitation (GR19), Mexico City, Mexico, July 5-9, 201

    Synthesis and Evaluation of 99mTc-Labelled Monoclonal Antibody 1D09C3 for Molecular Imaging of Major Histocompatibility Complex Class II Protein Expression

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    Purpose: It is known that major histocompatibility complex class II protein HLA-DR is highly expressed in B-cell lymphomas and in a variety of autoimmune and inflammatory diseases. Therefore, a radiolabelled fully humanized IgG4 monoclonal antibody (mAb) can provide useful prognostic and diagnostic information. Aims of the present study were to radiolabel an anti-HLA-DR mAb with technetium-99m and to evaluate its binding specificity, tissue distribution and targeting potential. Procedures: For labelling, we compared a direct method, after 2-mercaptoethanol (2-ME) reduction of disulphide bonds, with a two-step labelling method, using a heterobifunctional succinimidyl-6-hydrazinonicotinate hydrochloride chelator. Several in vitro quality controls and in vivo experiments in mice were performed. Results: We obtained highest labelling efficiency (LE, 998%) and specific activity (SA; 5,550 MBq/mg) via the direct method. In vitro quality control showed good stability, structural integrity and retention of the binding properties of the labelled mAb. The biodistribution in mice showed high and persistent uptake in spleen and suggests kidney and liver-mediated clearanc

    Biopsy Sampling in Upper Gastrointestinal Endoscopy : A Survey from 10 Tertiary Referral Centres across Europe

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    Funding Information: A. Link reports grants from European Commission “Eu-ropäischer Fond für regionale Entwicklung” (EFRE), outside the submitted work. In Lithuania the work was partly supported by Lithuanian Research Council Grant no APP-2/2016. In Latvia, the methodological support was made available from the project lzp-2018/1-0135. This work was also supported by the NIHR Oxford Biomedical Research Centre (The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care). In Barcelona, we thank the CERCA Programme/Generalitat de Catalunya for the support. Publisher Copyright: © 2020 The Author(s) Published by S. Karger AG, Basel.Background: Guidelines give robust recommendations on which biopsies should be taken when there is endoscopic suggestion of gastric inflammation. Adherence to these guidelines often seems arbitrary. This study aimed to give an overview on current practice in tertiary referral centres across Europe. Methods: Data were collected at 10 tertiary referral centres. Demographic data, the indication for each procedure, endoscopic findings, and the number and sampling site of biopsies were recorded. Findings were compared between centres, and factors influencing the decision to take biopsies were explored. Results: Biopsies were taken in 56.6% of 9,425 procedures, with significant variation between centres (p < 0.001). Gastric biopsies were taken in 43.8% of all procedures. Sampling location varied with the procedure indication (p < 0.001) without consistent pattern across the centres. Fewer biopsies were taken in centres which routinely applied the updated Sydney classification for gastritis assessment (46.0%), compared to centres where this was done only upon request (75.3%, p < 0.001). This was the same for centres stratifying patients according to the OLGA system (51.8 vs. 73.0%, p < 0.001). More biopsies were taken in centres following the MAPS guidelines on stomach surveillance (68.1 vs. 37.1%, p < 0.001). Biopsy sampling was more likely in younger patients in 8 centres (p < 0.05), but this was not true for the whole cohort (p = 0.537). The percentage of procedures with biopsies correlated directly with additional costs charged in case of biopsies (r = 0.709, p = 0.022). Conclusion: Adherence to guideline recommendations for biopsy sampling at gastroscopy was inconsistent across the participating centres. Our data suggest that centre-specific policies are applied instead.publishersversionPeer reviewe

    Magnetic Field Generation in Stars

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    Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence,in the generation and stability of neutron star fields. Independent information on the internal magnetic field of neutron stars will come from future gravitational wave detections. Thus we maybe at the dawn of a new era of exciting discoveries in compact star magnetism driven by the opening of a new, non-electromagnetic observational window. We also review recent advances in the theory and computation of magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo theory. These advances offer insight into the action of stellar dynamos as well as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field generation in stars to appear in Space Science Reviews, Springe

    Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

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    An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic epep scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

    A Search for Selectrons and Squarks at HERA

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    Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure
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