6,619 research outputs found
Discovery of Two High-Magnetic-Field Radio Pulsars
We report the discovery of two young isolated radio pulsars with very high
inferred magnetic fields. PSR J1119-6127 has period P = 0.407 s, and the
largest period derivative known among radio pulsars, Pdot = 4.0e-12. Under
standard assumptions these parameters imply a characteristic spin-down age of
only tau = 1.6 kyr and a surface dipole magnetic field strength of B = 4.1e13
G. We have measured a stationary period-second-derivative for this pulsar,
resulting in a braking index of n = 2.91+-0.05. We have also observed a glitch
in the rotation of the pulsar, with fractional period change Delta_P/P =
-4.4e-9. Archival radio imaging data suggest the presence of a previously
uncataloged supernova remnant centered on the pulsar. The second pulsar, PSR
J1814-1744, has P = 3.975 s and Pdot = 7.4e-13. These parameters imply tau = 85
kyr, and B = 5.5e13 G, the largest of any known radio pulsar.
Both PSR J1119-6127 and PSR J1814-1744 show apparently normal radio emission
in a regime of magnetic field strength where some models predict that no
emission should occur. Also, PSR J1814-1744 has spin parameters similar to the
anomalous X-ray pulsar (AXP) 1E 2259+586, but shows no discernible X-ray
emission. If AXPs are isolated, high magnetic field neutron stars
(``magnetars''), these results suggest that their unusual attributes are
unlikely to be merely a consequence of their very high inferred magnetic
fields.Comment: 7 pages, 3 embedded EPS figures, to be published in Ap
Random access quantum information processors
Qubit connectivity is an important property of a quantum processor, with an
ideal processor having random access -- the ability of arbitrary qubit pairs to
interact directly. Here, we implement a random access superconducting quantum
information processor, demonstrating universal operations on a nine-bit quantum
memory, with a single transmon serving as the central processor. The quantum
memory uses the eigenmodes of a linear array of coupled superconducting
resonators. The memory bits are superpositions of vacuum and single-photon
states, controlled by a single superconducting transmon coupled to the edge of
the array. We selectively stimulate single-photon vacuum Rabi oscillations
between the transmon and individual eigenmodes through parametric flux
modulation of the transmon frequency, producing sidebands resonant with the
modes. Utilizing these oscillations for state transfer, we perform a universal
set of single- and two-qubit gates between arbitrary pairs of modes, using only
the charge and flux bias of the transmon. Further, we prepare multimode
entangled Bell and GHZ states of arbitrary modes. The fast and flexible
control, achieved with efficient use of cryogenic resources and control
electronics, in a scalable architecture compatible with state-of-the-art
quantum memories is promising for quantum computation and simulation.Comment: 7 pages, 5 figures, supplementary information ancillary file, 21
page
Forming norms: informing diagnosis and management in sports medicine
Clinicians aim to identify abnormalities, and distinguish harmful from harmless abnormalities. In sports medicine, measures of physical function such as strength, balance and joint flexibility are used as diagnostic tools to identify causes of pain and disability and monitor progression in response to an intervention. Comparing results from clinical measures against ‘normal’ values guides decision-making regarding health outcomes. Understanding ‘normal’ is therefore central to appropriate management of disease and disability. However, ‘normal’ is difficult to clarify and definitions are dependent on context. ‘Normal’ in the clinical setting is best understood as an appropriate state of physical function. Particularly as disease, pain and sickness are expected occurrences of being human, understanding ‘normal’ at each stage of the lifespan is essential to avoid the medicalisation of usual life processes. Clinicians use physical measures to assess physical function and identify disability. Accurate diagnosis hinges on access to ‘normal’ reference values for such measures. However our knowledge of ‘normal’ for many clinical measures in sports medicine is limited. Improved knowledge of normal physical function across the lifespan will assist greatly in the diagnosis and management of pain, disease and disability
The inter-rater reliability of the diagnosis of surgical site infection in the context of a clinical trial.
ObjectivesThe diagnosis of surgical site infection following endoprosthetic reconstruction for bone tumours is frequently a subjective diagnosis. Large clinical trials use blinded Central Adjudication Committees (CACs) to minimise the variability and bias associated with assessing a clinical outcome. The aim of this study was to determine the level of inter-rater and intra-rater agreement in the diagnosis of surgical site infection in the context of a clinical trial.Materials and methodsThe Prophylactic Antibiotic Regimens in Tumour Surgery (PARITY) trial CAC adjudicated 29 non-PARITY cases of lower extremity endoprosthetic reconstruction. The CAC members classified each case according to the Centers for Disease Control (CDC) criteria for surgical site infection (superficial, deep, or organ space). Combinatorial analysis was used to calculate the smallest CAC panel size required to maximise agreement. A final meeting was held to establish a consensus.ResultsFull or near consensus was reached in 20 of the 29 cases. The Fleiss kappa value was calculated as 0.44 (95% confidence interval (CI) 0.35 to 0.53), or moderate agreement. The greatest statistical agreement was observed in the outcome of no infection, 0.61 (95% CI 0.49 to 0.72, substantial agreement). Panelists reached a full consensus in 12 of 29 cases and near consensus in five of 29 cases when CDC criteria were used (superficial, deep or organ space). A stable maximum Fleiss kappa of 0.46 (95% CI 0.50 to 0.35) at CAC sizes greater than three members was obtained.ConclusionsThere is substantial agreement among the members of the PARITY CAC regarding the presence or absence of surgical site infection. Agreement on the level of infection, however, is more challenging. Additional clinical information routinely collected by the prospective PARITY trial may improve the discriminatory capacity of the CAC in the parent study for the diagnosis of infection.Cite this article: J. Nuttall, N. Evaniew, P. Thornley, A. Griffin, B. Deheshi, T. O'Shea, J. Wunder, P. Ferguson, R. L. Randall, R. Turcotte, P. Schneider, P. McKay, M. Bhandari, M. Ghert. The inter-rater reliability of the diagnosis of surgical site infection in the context of a clinical trial. Bone Joint Res 2016;5:347-352. DOI: 10.1302/2046-3758.58.BJR-2016-0036.R1
Volatile Composition and Outgassing in C/2018 Y1 (IWAMOTO): Extending Detection Limits for High-Resolution IR Cometary Spectroscopy at the NASA-IRTF
We used iSHELL, the powerful high-resolution ( /~ 40,000) cross-dispersed IR spectrograph at the NASA-IRTF to measure the native ice composition and outgassing of moderately bright, long-period comet C/2018 Y1 (Iwamoto) (hereafter Y1) within weeks of its discovery. We measured production rates for H2O, and production rates and abundance ratios relative to H2O for eight trace molecules, including the most complete measure of cometary CH4 achieved to date. Compared with mean abundances measured among comets, our study revealed enriched CH3OH and C2H6 yet depleted CO and C2H2, perhaps indicating highly efficient H- atom addition on interstellar grains prior to their incorporation into the nucleus. The combined high spectral resolving power and broad spectral coverage of iSHELL allowed characterizing cometary composition using only three instrument settings, and its long-slit coverage allowed comparing the spatial distributions of molecular emissions and dust continuum
Signatures of Pseudoscalar Photon Mixing in CMB Radiation
We model the effect of photon and ultra-light pseudoscalar mixing on the
propagation of electromagnetic radiation through the extragalactic medium. The
medium is modelled as a large number of magnetic domains, uncorrelated with one
another. We obtain an analytic expression for the different Stokes parameters
in the limit of small mixing angle. The different Stokes parameters are found
to increase linearly with the number of domains. We also verify this result by
direct numerical simulations. We use this formalism to estimate the effect of
pseudoscalar-photon mixing on the Cosmic Microwave Background (CMB)
polarization. We impose limits on the model parameters by the CMB observations.
We find that the currently allowed parameter range admits a CMB circular
polarization up to order .Comment: 17 pages, 5 figure
Discovery of Five Binary Radio Pulsars
We report on five binary pulsars discovered in the Parkes multibeam Galactic
plane survey. All of the pulsars are old, with characteristic ages 1-11 Gyr,
and have relatively small inferred magnetic fields, 5-90e8 G. The orbital
periods range from 1.3 to 15 days. As a group these objects differ from the
usual low-mass binary pulsars (LMBPs): their spin periods of 9-88 ms are
relatively long; their companion masses, 0.2-1.1 Msun, are, in at least some
cases, suggestive of CO or more massive white dwarfs; and some of the orbital
eccentricities, 1e-5 < e < 0.002, are unexpectedly large. We argue that these
observed characteristics reflect binary evolution that is significantly
different from that of LMBPs. We also note that intermediate-mass binary
pulsars apparently have a smaller scale-height than LMBPs.Comment: 5 pages, 4 embedded EPS figs, accepted for publication by ApJ Letter
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