Particle creation in a Robertson-Walker Universe revisited

We reanalyze the problem of particle creation in a 3+1 spatially closed Robertson-Walker space-time. We compute the total number of particles produced by this non-stationary gravitational background as well as the corresponding total energy and find a slight discrepancy between our results and those recently obtained in the literatur

Photoionization modeling of the Galactic planetary nebulae Abell 39 and NGC 7027

We estimate distances to the spherical planetary nebula Abell 39 and the bipolar planetary nebula NGC 7027 by interpolating from a wide grid of photoionization models using the 3-D code, MOCASSIN. We find preliminary distances of 1.5 kpc and 0.9 kpc respectively, with uncertainties of about 30%.Comment: 2 pages, 1 figure, presented at the IAU Symposium 283 "Planetary Nebulae: an Eye to the Future", Puerto de la Cruz, Tenerife, Spain, 201

The diet and ecological role of giraffe (Giraffa camelopardalis) introduced to the Eastern Cape, South Africa

With an increase in the popularity of wildlife ranching in southern Africa has come the introduction of non-native (extralimital) mammalian herbivores. Financial gain has arguably been at the forefront of these introductions, with little or no assessment of the ecological consequences. The diet of three populations of introduced giraffe Giraffa camelopardalis was assessed by direct observation in the Eastern Cape Province, South Africa between January 2002 and October 2003, as the first step towards understanding the ecological role played by giraffe in the region. Similar to the diet of giraffe within their native range, a deciduous species from the genus Acacia (Acacia karroo) was the most important species in the diet. Giraffe in the Eastern Cape Province, however, consumed more evergreen species than those within their native range. The relative lack of deciduous species in the Eastern Cape Province provides a probable explanation for such a result. Seasonal variation in the consumption of the most important species in the diet was evident with members of the genus Rhus being more important in the winter months. This was attributed to the deciduous nature of A. karroo. The potential for giraffe to have a detrimental effect on the indigenous vegetation is discussed. We conclude that the study provides a much-needed list of plant species threatened by giraffe browsing in a region where the vegetation is thought to have evolved in the absence of such a browser

Lessons from aloes in the Thicket Biome: reconstructing past elephant browsing to understand the present

It is very difficult to quantify elephant-induced change to vegetation in the absence of adequate historical benchmarks. In this commentary, we explore the historical distribution of aloes in the Thicket Biome of South Africa. We contend that the large stands of aesthetically pleasing aloes in the Thicket Biome can be likened to the even-aged stands of tall trees in the riparian forests of Botswana, both being artefacts of the loss of large herbivores through disease and hunting in the past. Elephant browsing on aloes may therefore be the first step in the vegetation reverting to a situation similar to the one prior to excessive hunting in the region

Far Ultraviolet Diffuse Emission from the Large Magellanic Cloud

We present the first observations of diffuse radiation in the far ultraviolet (1000 -- 1150 \AA) from the Large Magellanic Cloud based on observations made with the {\it Far Ultraviolet Spectroscopic Explorer}. The fraction of the total radiation in the field emitted as diffuse radiation is typically 5 -- 20\% with a high of 45\% near N70 where there are few exciting stars, indicating that much of the emission is not due to nearby stars. Much less light is scattered in the far ultraviolet than at longer wavelengths with the stellar radiation going into heating the interstellar dust.Comment: Accepted in ApJ Letter

Can general practitioner commissioning deliver equity and excellence? : Evidence from two studies of service improvement in the English NHS

Objectives: To explore some of the key assumptions underpinning the continued development of general practitioner-led commissioning in health services. Methods: Qualitative data from two studies of service improvement in the English NHS were considered against England's plans for GP-led commissioning. These data were collected through in-depth interviews with a total of 187 professionals and 99 people affected by services in 10 different primary care trust areas across England between 2008 and 2009. Results: Internationally, GPs are seen to have a central position in health systems. In keeping with this, the English policy places emphasis on the 'pivotal role' of general practitioners, considered to be ideally placed to commission in the best interests of their patients. However, our evidence suggests that general practitioners do not always have a pivotal role for all patients. Moreover, it is planned that the new commissioning groups in England will not be subject to top-down performance management and this raises the question of how agreed quality standards will be met under the proposed new system. Conclusions: This paper questions the assumption that GPs are best placed to commission health services in a way that meets quality standards and leads to equitable outcomes. There is little evidence to suggest that GPs will succeed where others have failed and a risk that, without top-down performance management, service improvement will be patchy, leading to greater, not reduced, inequity

The use of archaeological and ethnographical information to supplement the historical record of the distribution of large mammalian herbivores in South Africa

Introduction: The introduction of animal taxa to areas where they do not naturally occur has the potential to damage severely the native fauna and flora. Introductions, both accidental and intentional, to Australia, New Zealand, Marion Island and other oceanic islands provide spectacular examples of this.1,2 Non-native mammalian herbivores often become invasive in the absence of their natural predators2 and their impact on vegetation, which may include alterations to plant species composition, structure and diversity, is exaggerated, especially if the vegetation has evolved in the absence of similar herbivores.3,4 This influence is not limited to the direct consequence for the vegetation and there may be a cascade effect on ecosystem functioning through, for example, a decline in the amount of available forage for indigenous herbivores,3 a reduction in the breeding efficiency of birds that rely on the vegetation,5,6 and a negative effect on carbon storage by transforming stands of dense vegetative cover to open savannah like systems.7 Nor are these outcomes restricted to non-native herbivores; the re-introduction of a species, such as the elephant (Loxodonta africana), to areas from which it has been absent for many years may have similar consequences.8–11 Additional problems associated with the uncontrolled movement of large mammals include the transmission of disease, such as brucellosis in the United States,3 and a threat to the genetic integrity of a species through hybridization.12 It is thus clear that deliberate introductions of herbivores to areas where they do not naturally occur may not be sound conservation practice

Assessment of regional myocardial blood flow and regional fractional oxygen extraction in dogs, using 15O-water and 15O-hemoglobin

A new approach to the assessment of regional myocardial blood flow and fractional oxygen extraction has been developed using 15O-water (H2- 15O) and 15O-hemoglobin (15O-Hb). Bolus doses (1 mCi) of H2-15O and 15O- Hb were injected 10 minutes apart into the left main coronary artery of 12 normal dogs. Sequential images of regional myocardial tracer clearance were obtained over 5 minutes with a positron camera. Myocardial blood flow calculated from the monoexponential washout of H2- 15O after background correction was 78 +/- 6 (SE) ml/100 g per min. Functional images of regional blood flow in which the image of peak activity was divided by the integrated image of H2-15O washout were derived by computer processing. These images demonstrated homogeneous blood flow in the normal myocardium. Fractional myocardial O2 extraction was determined from an image of initial distribution of O2 used (obtained by extrapolating back to time zero the series of images obtained after 15O-Hb administration), divided by initial distribution of O2 delivered (obtained by back extrapolating H2-15O washout). These functional images showed uniform distribution of fractional O2 extraction in the normal myocardium. Thus, these studies show that regional myocardial blood flow and regional oxygen extraction can be measured simultaneously by sequential imaging after serial intracoronary injections of H2-15O and 15O-Hb

Integrated policy making in England for adults with long-term neurological conditions (LTNCs): some preliminary findings from a scoping study

Introduction: Long-term neurological conditions are a major cause of disability in the UK and internationally. Their successful management, in order to enhance health and well-being, requires both sophisticated organisation across a number of health, social care and other service boundaries, and the real involvement of people with neurological conditions and members of their support networks. <br><br> Policy development: This paper reports on part of the preliminary scoping phase of a study designed to evaluate the impact of the National Service Framework for long-term neurological conditions on integrated care. It describes current policies in England and reports on discussions with a range of people involved in the planning, provision or use of services, which took place during the scoping exercise. These interviews inform how policy affecting people with long-term neurological conditions has been received and implemented so far. <br><br> Conclusion and discussion: Findings suggest that progress towards integrated service provision is patchy and slow. In the competing priorities within government policy, neurological conditions have tended to be marginalised, within healthcare policy generally and in initiatives to support people with long-term conditions in particular. The reasons for this are explored and will inform the next stages of the research