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The exposure of two senior republicans as informers for British intelligence in 2005 led to a popular perception that the IRA had 'lost' the intelligence war and was pressurised into peace. In this first in-depth study across the entire conflict, Thomas Leahy re-evaluates the successes and failures of Britain's intelligence activities against the IRA, from the use of agents and informers to special-forces, surveillance and electronic intelligence. Using new interview material alongside memoirs and Irish and UK archival materials, he suggests that the IRA was not forced into peace by British intelligence. His work sheds new light on key questions in intelligence and security studies. How does British intelligence operate against paramilitaries? Is it effective? When should governments 'talk to terrorists'? And does regional variation explain the outcome of intelligence conflicts? This is a major contribution to the history of the conflict and of why peace emerged in Northern Ireland.
We have detected 27 new supernova remnants (SNRs) using a new data release of the GLEAM survey from the Murchison Widefield Array telescope, including the lowest surface brightness SNR ever detected, G 0.1 – 9.7. Our method uses spectral fitting to the radio continuum to derive spectral indices for 26/27 candidates, and our low-frequency observations probe a steeper spectrum population than previously discovered. None of the candidates have coincident WISE mid-IR emission, further showing that the emission is non-thermal. Using pulsar associations we derive physical properties for six candidate SNRs, finding G 0.1 – 9.7 may be younger than 10 kyr. Sixty per cent of the candidates subtend areas larger than 0.2 deg2 on the sky, compared to < 25% of previously detected SNRs. We also make the first detection of two SNRs in the Galactic longitude range 220°–240°.
We examined the latest data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey covering 345° < l < 60° and 180° < l < 240°, using these data and that of the Widefield Infrared Survey Explorer to follow up proposed candidate Supernova Remnant (SNR) from other sources. Of the 101 candidates proposed in the region, we are able to definitively confirm ten as SNRs, tentatively confirm two as SNRs, and reclassify five as H ii regions. A further two are detectable in our images but difficult to classify; the remaining 82 are undetectable in these data. We also investigated the 18 unclassified Multi-Array Galactic Plane Imaging Survey (MAGPIS) candidate SNRs, newly confirming three as SNRs, reclassifying two as H ii regions, and exploring the unusual spectra and morphology of two others.
We have observed the G23 field of the Galaxy AndMass Assembly (GAMA) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) in its commissioning phase to validate the performance of the telescope and to characterise the detected galaxy populations. This observation covers ~48 deg2 with synthesised beam of 32.7 arcsec by 17.8 arcsec at 936MHz, and ~39 deg2 with synthesised beam of 15.8 arcsec by 12.0 arcsec at 1320MHz. At both frequencies, the root-mean-square (r.m.s.) noise is ~0.1 mJy/beam. We combine these radio observations with the GAMA galaxy data, which includes spectroscopy of galaxies that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry is used to determine which galaxies host an active galactic nucleus (AGN). In properties including source counts, mass distributions, and IR versus radio luminosity relation, the ASKAP-detected radio sources behave as expected. Radio galaxies have higher stellar mass and luminosity in IR, optical, and UV than other galaxies. We apply optical and IR AGN diagnostics and find that they disagree for ~30% of the galaxies in our sample. We suggest possible causes for the disagreement. Some cases can be explained by optical extinction of the AGN, but for more than half of the cases we do not find a clear explanation. Radio sources aremore likely (~6%) to have an AGN than radio quiet galaxies (~1%), but the majority of AGN are not detected in radio at this sensitivity.
Breastfeeding may reduce obesity risk, but this association could be confounded by breastfeeding families’ characteristics. We investigated if body composition differs at birth among infants who were either exclusively breast- or formula-fed. We hypothesized the two groups would differ in body composition, even at birth, prior to their post-natal feeding experience. Healthy primiparous carrying singleton pregnancy were recruited at 15 weeks’ gestation. PEA POD® measured body composition within 72 hours of delivery and infant feeding was prospectively captured. Out of the 1,152 infants recruited, 117 (10.2%) and 239 (20.7%) went on to be either exclusively breast- or formula-fed, respectively. Breastfed infants were heavier at birth, but their percentage fat mass (FM) was lower than that of exclusively formula-fed infants (covariate adjusted β = −1.91 percentage points of FM; 95% CI −2.82 to −1.01). Differences in intra-uterine exposures, irrespective of early diet, may partly explain an infant’s obesity risk.
Eight ruminally-fistulated wethers were used to examine the temporal effects of afternoon (PM; 1600h) v. morning (AM; 0800 h) allocation of fresh spring herbage from a perennial ryegrass (Lolium perenne L.)-based pasture on fermentation and microbial community dynamics. Herbage chemical composition was minimally affected by time of allocation, but daily mean ammonia concentrations were greater for the PM group. The 24-h pattern of ruminal fermentation (i.e. time of sampling relative to time of allocation), however, varied considerably for all fermentation variables (P⩽0.001). Most notably amongst ruminal fermentation characteristics, ammonia concentrations showed a substantial temporal variation; concentrations of ammonia were 1.7-, 2.0- and 2.2-fold greater in rumens of PM wethers at 4, 6 and 8h after allocation, respectively, compared with AM wethers. The relative abundances of archaeal and ciliate protozoal taxa were similar across allocation groups. In contrast, the relative abundances of members of the rumen bacterial community, like Prevotella 1 (P=0.04), Bacteroidales RF16 group (P=0.005) and Fibrobacter spp. (P=0.008) were greater for the AM group, whereas the relative abundance of Kandleria spp. was greater (P=0.04) for the PM group. Of these taxa, only Prevotella 1 (P=0.04) and Kandleria (P<0.001) showed a significant interaction between time of allocation and time of sampling relative to feed allocation. Relative abundances of Prevotella 1 were greater at 2h (P=0.05), 4h (P=0.003) and 6h (P=0.01) after AM allocation of new herbage, whereas relative abundances of Kandleria were greater at 2h (P=0.003) and 4h (P<0.001) after PM allocation. The early post-allocation rise in ammonia concentrations in PM rumens occurred simultaneously with sharp increases in the relative abundance of Kandleria spp. and with a decline in the relative abundance of Prevotella. All measures of fermentation and most microbial community composition data showed highly dynamic changes in concentrations and genus abundances, respectively, with substantial temporal changes occurring within the first 8h of allocating a new strip of herbage. The dynamic changes in the relative abundances of certain bacterial groups, in synchrony with a substantial diurnal variation in ammonia concentrations, has potential effects on the efficiency by which N is utilised by the grazing ruminant.
We present first results of the deprojection of some optical and radio images of planetary nebulae using an iterative technique based on the Lucy method, as discussed in Leahy (1991). This approach allows a greater range of possible geometries to be investigated and is less sensitive to the effects of noise compared with the direct matrix-inversion method which can be used for the spherical case. We assume that the emissivity function can be represented as
Among dinosaurs, megadinosaurs (those over one tonne) have been considered among the best candidates for having had low metabolic rates (LoMRs). Spotila et al (1991) argued that big dinosaurs were gigantotherms that shared thermal characteristics with the large leatherback sea turtle, and Dodson (1991) suggested that giant dinosaurs lived in the slow lane compared to giant mammals. Coulson (1979), Bennett (1991) and Ruben (1991) restored big dinosaurs as “good reptiles” powered by bursts of reptilian hyperanaerobiosis rather than the sustained tachyaerobiosis that powers birds and mammals. Farlow (1990) suggested that large dinosaurs were “damned good reptiles” with fluctuating metabolic rates (MRs), and in 1993 he argued that dinosaurs used a combination of rapid reproduction and intermediate metabolic rates (InMRs) to grow bigger than land mammals. All the above workers, and McNab (1983) and Dunham et al. (1989), have modeled big dinosaurs as LoMR or InMR inertial homeotherms that maintained constant body temperatures on a daily basis.
Evolution of cold dry snow and firn plays important roles in glaciology; however, the physical formulation of a densification law is still an active research topic. We forced eight firn-densification models and one seasonal-snow model in six different experiments by imposing step changes in temperature and accumulation-rate boundary conditions; all of the boundary conditions were chosen to simulate firn densification in cold, dry environments. While the intended application of the participating models varies, they are describing the same physical system and should in principle yield the same solutions. The firn models all produce plausible depth-density profiles, but the model outputs in both steady state and transient modes differ for quantities that are of interest in ice core and altimetry research. These differences demonstrate that firn-densification models are incorrectly or incompletely representing physical processes. We quantitatively characterize the differences among the results from the various models. For example, we find depth-integrated porosity is unlikely to be inferred with confidence from a firn model to better than 2 m in steady state at a specific site with known accumulation rate and temperature. Firn Model Intercomparison Experiment can provide a benchmark of results for future models, provide a basis to quantify model uncertainties and guide future directions of firn-densification modeling.
We have observed 20 classical double radio galaxies and quasars with MERLIN at 151 MHz. We discuss the systematic variation of the bridge structures with radio power and the nature of the identification.
The Cygnus Loop is one of the nearest supernova remnants (440 pc) and has been studied extensively in radio through X-ray wavelengths. An unusual bright “V”-shaped region on the south-western limb (near RA 20h46m and Decl. +30°) was revealed in ROSAT PSPC observations of the Cygnus Loop. The left side of the “V” has one of the highest hardness ratios (0.9–2 keV / 0.1–0.4 keV) in the Cygnus Loop whereas the right side has one of the lowest. Images and spatially resolved spectra were obtained using Chandra ACIS observations. Some results of analysis of the images and spectra are presented here.
A model is developed here to reproduce the pulse shape of Her X-1. The 35-day cycle of pulse shape changes during the 35-day Her X-1 cycle “High – Low – Short High – Low” is caused by varying obscuration of the emission region by the accretion disk. The observed sequence of pulse shape changes imply a pencil beam from the near pole and a fan beam from the far pole. Using a newly developed code for modeling accretion column emission, including accurate treatment of gravitational light-bending effects, the observed pulse shape of Her X-1 is modeled here.
LSI +61°303 outbursts are modeled as a pulsar wind nebula expanding inside the environment provided by the Be companion star's stellar wind and photon flux. A set of equations describing the system is developed and solved numerically for representative sets of parameters. Emission in X-rays through gamma-rays is due to inverse Compton emission from relativistic electrons around the pulsar. The radio emission is due to synchrotron emission of varying optical depth, which yields a varying spectral index. The peak of X-ray emission is near periastron and the peak of the radio emission is near apastron, due to reduced confining pressure on the relativistic electron cloud and its subsequent rapid expansion.
We review the evidence that spectral curvature in the extended emission of radio galaxies is caused by synchrotron losses, and that the spatial variation can be interpreted to yield ages and expansion speeds. One of the biggest worries has been the true value of the magnetic field, but X-ray detections of inverse-Compton radiation are beginning to suggest that “minimum energy” estimates are remarkably accurate. A critical test is to compare model and observed spectra over a broad frequency range; to date this has has only been done for Cygnus A, and the results proved controversial. Here we discuss several more cases and begin to draw some general conclusions.
Hotspots are usually well fitted by continuous injection models, as expected. In two cases the implied injection index is flatter than 0.5, too flat to be produced by standard Fermi acceleration in a non-relativistic shock. The bridge spectra are reasonably fitted by single-burst models, but in some objects the injection index is not constant across the lobes, showing instead a tendency to steepen in the inner bridge, where the break frequencies are lowest. The true spectral shape may be a more gradual curve than the standard models, possibly because of mixing of electron populations with different ages. Our results are limited by the inaccuracy of the absolute flux density scale, especially at low frequencies, and a fresh attack on the flux scale would be timely.