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We report progress on research relating to 36.2 GHz extragalactic class I methanol masers, including a review of published work and new observations at high angular resolution. These observations reveal that extragalactic class I masers are excited in shocked gas and maybe associated with starbursts, galactic-scale outflows from active galactic nuclei (AGNs) feedback, or the inner-end region of the galactic bar. The current observational results suggests that extragalactic class I methanol masers provide a new probe for starbursts and feedback in active galaxies.
The RadioAstron space-VLBI mission has successfully detected extragalactic H2O MegaMaser emission regions at very long Earth to space baselines ranging between 1.4 and 26.7 Earth Diameters (ED). The preliminary results for two galaxies, NGC 3079 and NGC 4258, at baselines longer than one ED indicate masering environments and excitation conditions in these galaxies that are distinctly different. Further observations of NGC 4258 at even longer baselines are expected to reveal more of the physics of individual emission regions.
We have detected maser emission from the 36.2 GHz (4−1 → 30E) methanol transition towards NGC 4945. This emission has been observed in two separate epochs and is approximately five orders of magnitude more luminous than typical emission from this transition within our Galaxy. NGC 4945 is only the fourth extragalactic source observed hosting class I methanol maser emission. Extragalactic class I methanol masers do not appear to be simply highly-luminous variants of their galactic counterparts and instead appear to trace large-scale regions where low-velocity shocks are present in molecular gas.
The Australia Telescope Compact Array (ATCA) participated in a number of survey programs to search for and image common class I methanol masers (at 36 and 44 GHz) with high angular resolution. In this paper, we discuss spatial and velocity distributions revealed by these surveys. In particular, the number of maser regions is found to fall off exponentially with the linear distance from the associated young stellar object traced by the 6.7-GHz maser, and the scale of this distribution is 263±15 milliparsec. Although this relationship still needs to be understood in the context of the broader field, it can be utilised to estimate the distance using methanol masers only. This new technique has been analysed to understand its limitations and future potential. It turned out, it can be very successful to resolve the ambiguity in kinematic distances, but, in the current form, is much less accurate (than the kinematic method) if used on its own.
NGC 253 is one of the closest starburst galaxies to the Milky Way and as such it has been studied in detail across the electromagnetic spectrum. Recent observations have detected the first extragalactic class I methanol masers at 36 and 44 GHz and the first extragalactic HC3N (cyanoacetylene) masers in this source. Here we discuss the location of the masers with respect to key morphological features within NGC 253 and the association between the masers and the ongoing starburst.
The exclusive association of Class II methanol masers with high mass star formation regions and in turn spiral arms, makes them ideal tracers of spiral structure. The bright and compact nature of masers also makes them good sources for Very Long Baseline Interferometry, with their fluxes visible on some of the longest terrestrial baselines. The success of the BeSSeL (Bar and Spiral Structure Legacy) project has demonstrated the use of masers in large scale high–precision trigonometric parallax surveys. This survey was then able to precisely map the spiral arms visible from the Northern Hemisphere and recalculate the fundamental Milky Way parameters R0 and θ0. The majority of the Milky Way is visible from the Southern Hemisphere and at the present time the Australian LBA (Long Baseline Array) is the only Southern Hemisphere array capable of taking high–precision trigonometric parallax data. We present the progress–to–date of the Southern Hemisphere experiment. We will also unveil a new broadband Southern Hemisphere array, capable of much faster parallax turnaround and atmospheric calibration.
The well known jet in M87 (Virgo A) has been extensively studied in the radio regime using conventional arrays with resultant resolutions in the range 0.22–1 arcsecond. We present here the results of a VLBI experiment to map the jet over its entire length (30 arcseconds) to high resolution. The observations were made in April 1984 at 1.67 GHz with a ‘World Array’ containing 18 VLBI telescopes. In addition, simultaneous observations were performed with the 6 station MERLIN array.
St Andrews was of tremendous significance in medieval Scotland. Its importance remains readily apparent in the buildings which cluster the rocky promontory jutting out into the North Sea: the towers and walls of cathedral, castle and university provide reminders of the status and wealth of the city in the Middle Ages. As a centre of earthly and spiritual government, as the place of veneration forScotland's patron saint and as an ancient seat of learning, St Andrews was the ecclesiastical capital of Scotland. This volume provides the first full study of this special and multi-faceted centre throughout its golden age. The fourteen chapters use St Andrews as a focus for the discussion of multiple aspects of medieval life in Scotland. They examine church, spirituality, urban society andlearning in a specific context from the seventh to the sixteenth century, allowing for the consideration of St Andrews alongside other great religious and political centres of medieval Europe.
Michael Brown is Professor of Medieval Scottish History, University of St Andrews; Katie Stevenson is Keeper of Scottish History and Archaeology, National Museums Scotland and Senior Lecturer in Late Medieval History, University of St Andrews.
Contributors: Michael Brown, Ian Campbell, David Ditchburn, Elizabeth Ewan, Richard Fawcett, Derek Hall, Matthew Hammond, Julian Luxford, Roger Mason, Norman Reid, Bess Rhodes, Catherine Smith, Katie Stevenson, Simon Taylor, Tom Turpie.
This study investigated comparatively the pathogenicity of experimental infection of mice and guinea pigs, with Angiostrongylus mackerrasae and the closely related species A. cantonensis. Time course analyses showed that A. mackerrasae causes eosinophilic meningitis in these hosts, which suggests that the species has the potential to cause meningitis in humans and domestic animals. Both A. mackerrasae and the genetically similar A. cantonensis caused eosinophilic meningitis in mice at two time points of 14 and 21 days post infection (dpi). The brain lesions in mice infected with A. mackerrasae were more granulomatous in nature and the parasites were more likely to appear degenerate compared with lesions caused by A. cantonensis. This may indicate that the mouse immune system eliminates A. mackerrasae infection more effectively. The immunologic responses of mice infected with the two Angiostrongylus species was compared by assessing ex vivo stimulated spleen derived T cells and cytokines including interferon-gamma, interleukin 4 and interleukin 17 on 14 and 21 dpi. The results were similar for mice infected with A. cantonensis and A. mackerrasae. Serum from the infected animals with either A. cantonensis or A. mackerrasae recognized total soluble antigen of A. cantonensis female worms on Western blot.
Trypanosomes are blood-borne parasites that can cause severe disease in both humans and animals, yet little is known of the pathogenicity and life-cycles of trypanosomes in native Australian mammals. Trypanosoma copemani is known to be infective to a variety of Australian marsupials and has recently been shown to be potentially zoonotic as it is resistant to normal human serum. In the present study, in vivo and in vitro examination of blood and cultures from Australian marsupials was conducted using light microscopy, immunofluorescence, scanning electron microscopy and fluorescence in situ hybridization. Promastigote, sphaeromastigote and amastigote life-cycle stages were detected in vivo and in vitro. Novel trypanosome-like stages were also detected both in vivo and in vitro representing an oval stage, an extremely thin stage, an adherent stage and a tiny round stage. The tiny round and adherent stages appeared to adhere to erythrocytes causing potential haematological damage with clinical effects similar to haemolytic anaemia. The present study shows for the first time that trypomastigotes are not the only life-cycle stages circulating within the blood stream of trypanosome infected Australian native marsupials and provides insights into possible pathogenic mechanisms of this potentially zoonotic trypanosome species.
Examining the relationship between glucose intolerance and dietary intake in genetically similar populations with different dietary patterns and rates of type 2 diabetes may provide important insights into the role of diet in the pathogenesis of this disease. The objective of the present study was to assess the relationship between dietary variables and dysglycaemia/type 2 diabetes among three populations of African origin. The study design consists of a cross-sectional study of men and women of African descent aged 24–74 years from Cameroon (n 1790), Jamaica (n 857) and Manchester, UK (n 258) who were not known to have diabetes. Each participant had anthropometric measurements and underwent a 2 h 75 g oral glucose tolerance test. Habitual dietary intake was estimated with quantitative FFQ, developed specifically for each country. The age-adjusted prevalence of undiagnosed type 2 diabetes in Cameroon was low (1·1 %), but it was higher in Jamaica (11·6 %) and the UK (12·6 %). Adjusted generalised linear and latent mixed models used to obtain OR indicated that each 1·0 % increment in energy from protein, total fat and saturated fats significantly increased the odds of type 2 diabetes by 9 (95 % CI 1·02, 1·16) %, 5 (95 % CI, 1·01, 1·08) % and 16 (95 % CI 1·08, 1·25) %, respectively. A 1 % increase in energy from carbohydrates and a 0·1 unit increment in the PUFA:SFA ratio were associated with significantly reduced odds of type 2 diabetes. The results show independent effects of dietary factors on hyperglycaemia in African origin populations. Whether modifying intake of specific macronutrients helps diabetes prevention needs testing in randomised trials.