Impact of neutron star oscillations on the accelerating electric field in the polar cap of pulsar: or could we see oscillations of the neutron star after the glitch in pulsar?

Pulsar "standard model", that considers a pulsar as a rotating magnetized conducting sphere surrounded by plasma, is generalized to the case of oscillating star. We developed an algorithm for calculation of the Goldreich-Julian charge density for this case. We consider distortion of the accelerating zone in the polar cap of pulsar by neutron star oscillations. It is shown that for oscillation modes with high harmonic numbers (l,m) changes in the Goldreich-Julian charge density caused by pulsations of neutron star could lead to significant altering of an accelerating electric field in the polar cap of pulsar. In the moderately optimistic scenario, that assumes excitation of the neutron star oscillations by glitches, it could be possible to detect altering of the pulsar radioemission due to modulation of the accelerating field.Comment: 7 pages, 8 figures. Presented at the conference "Isolated Neutron Stars: from the Interior to the Surface", London, April 24-28, 2006; to appear in Astrophysics and Space Scienc

Plasma Magnetosphere Formation Around Oscillating Magnetized Neutron Stars

The notion of death line of rotating pulsars is applied to model of oscillating neutron stars. It is shown that the magnetosphere of typical non-rotating oscillating stars may not contain secondary plasma to support the generation of radio emission in the region of open field lines of plasma magnetosphere.Comment: Accepted for publication in Astrophysics & Space Scienc

r-modes in Relativistic Superfluid Stars

We discuss the modal properties of the $r$-modes of relativistic superfluid neutron stars, taking account of the entrainment effects between superfluids. In this paper, the neutron stars are assumed to be filled with neutron and proton superfluids and the strength of the entrainment effects between the superfluids are represented by a single parameter $\eta$. We find that the basic properties of the $r$-modes in a relativistic superfluid star are very similar to those found for a Newtonian superfluid star. The $r$-modes of a relativistic superfluid star are split into two families, ordinary fluid-like $r$-modes ($r^o$-mode) and superfluid-like $r$-modes ($r^s$-mode). The two superfluids counter-move for the $r^s$-modes, while they co-move for the $r^o$-modes. For the $r^o$-modes, the quantity $\kappa\equiv\sigma/\Omega+m$ is almost independent of the entrainment parameter $\eta$, where $m$ and $\sigma$ are the azimuthal wave number and the oscillation frequency observed by an inertial observer at spatial infinity, respectively. For the $r^s$-modes, on the other hand, $\kappa$ almost linearly increases with increasing $\eta$. It is also found that the radiation driven instability due to the $r^s$-modes is much weaker than that of the $r^o$-modes because the matter current associated with the axial parity perturbations almost completely vanishes.Comment: 14 pages, 4 figures. To appear in Physical Review

High frequency oscillations during magnetar flares

The recent discovery of high frequency oscillations during giant flares from the Soft Gamma Repeaters SGR 1806-20 and SGR 1900+14 may be the first direct detection of vibrations in a neutron star crust. If this interpretation is correct it offers a novel means of testing the neutron star equation of state, crustal breaking strain, and magnetic field configuration. We review the observational data on the magnetar oscillations, including new timing analysis of the SGR 1806-20 giant flare using data from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Rossi X-ray Timing Explorer (RXTE). We discuss the implications for the study of neutron star structure and crust thickness, and outline areas for future investigation.Comment: 5 pages, 1 figure, to appear in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface" (April 2006, London), eds. D. Page, R. Turolla, & S. Zane, Astrophysics & Space Science in pres

Three-dimensional general relativistic hydrodynamics II: long-term dynamics of single relativistic stars

This is the second in a series of papers on the construction and validation of a three-dimensional code for the solution of the coupled system of the Einstein equations and of the general relativistic hydrodynamic equations, and on the application of this code to problems in general relativistic astrophysics. In particular, we report on the accuracy of our code in the long-term dynamical evolution of relativistic stars and on some new physics results obtained in the process of code testing. The tests involve single non-rotating stars in stable equilibrium, non-rotating stars undergoing radial and quadrupolar oscillations, non-rotating stars on the unstable branch of the equilibrium configurations migrating to the stable branch, non-rotating stars undergoing gravitational collapse to a black hole, and rapidly rotating stars in stable equilibrium and undergoing quasi-radial oscillations. The numerical evolutions have been carried out in full general relativity using different types of polytropic equations of state using either the rest-mass density only, or the rest-mass density and the internal energy as independent variables. New variants of the spacetime evolution and new high resolution shock capturing (HRSC) treatments based on Riemann solvers and slope limiters have been implemented and the results compared with those obtained from previous methods. Finally, we have obtained the first eigenfrequencies of rotating stars in full general relativity and rapid rotation. A long standing problem, such frequencies have not been obtained by other methods. Overall, and to the best of our knowledge, the results presented in this paper represent the most accurate long-term three-dimensional evolutions of relativistic stars available to date.Comment: 19 pages, 17 figure

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

The Role, Status, and Working Conditions of Paraprofessionals: A National Survey of Academic Libraries

published or submitted for publicatio

Monitoring of livestock health and production in sub-Saharan Africa

We begin by stressing that relevant and adequate information is an essential ingredient of efficient decision-making processes aimed at optimising the performance of livestock enterprises. Such decisions are universally made, so that though different approaches may be required, animal health and production monitoring (HPM) is as important in sub-Saharan Africa (SSA) as it is in livestock systems in other parts of the world. To set the scene for our discussion of HPM in SSA, we broadly describe the main African production systems in tabular form, categorised by ecological conditions, production goals and input and output relations within a broad farming systems context. Subsequently, the scope and diversity of HPM in SSA is reviewed. This review reveals that in 2 decades of system monitoring, a wide variety of objectives have been tackled from broad system description and constraint diagnosis to more focused research to identify and quantify the impact of disease and other specific factors on the productivity of cattle and small ruminants. There have been many monitoring clients, ranging from national governments through aid agencies and the scientific community, to individual farmers. To serve these diverse clients and their objectives, a plethora of methods and data collection techniques have evolved, monitoring needs of two contrasting production systems (pastoralists in the arid and semi-arid zones and smallholder dairy farmers in the highlands of East Africa) to indicate how monitoring has contributed to our understanding of these systems and how monitoring might be better targeted to satisfy future needs. The impact of HPM on the `state of the knowledge' of traditional African production systems are then summarised at two levels. The first includes specific health and productivity information gained while the second considers the more general lessons learned with respect to livestock enterprise functions and their impact on human welfare. Finally, future monitoring needs are discussed relative to changes in African livestock systems. It is anticipated that further specialisation and intensification of livestock enterprises will require decision-support systems, many of which already exist in the developed world and could be adapted to SSA

Is logicist cognitive science possible?

No description supplie

NALP3 forms an IL-1beta-processing inflammasome with increased activity in Muckle-Wells autoinflammatory disorder.

Mutations within the NALP3/cryopyrin/CIAS1 gene are responsible for three autoinflammatory disorders: Muckle-Wells syndrome, familial cold autoinflammatory syndrome, and CINCA. The NALP3 protein is homologous to NALP1, which is a component of the inflammasome, a molecular platform that activates the proinflammatory caspases-1 and -5. NALP3 (and other members of the NALP family) lacks the C-terminal, CARD-containing sequence of NALP1, and its role in caspase activation is unclear. Here, we report that NALP2 and NALP3 associate with ASC, the CARD-containing protein Cardinal, and caspase-1 (but not caspase-5), thereby forming an inflammasome with high proIL-1beta-processing activity. Macrophages from Muckle-Wells patients spontaneously secrete active IL-1beta. Increased inflammasome activity is therefore likely to be the molecular basis of the symptoms associated with NALP3-dependent autoinflammatory disorders