The Role of Cold Flows in the Assembly of Galaxy Disks

We use high resolution cosmological hydrodynamical simulations to demonstrate that cold flow gas accretion, particularly along filaments, modifies the standard picture of gas accretion and cooling onto galaxy disks. In the standard picture, all gas is initially heated to the virial temperature of the galaxy as it enters the virial radius. Low mass galaxies are instead dominated by accretion of gas that stays well below the virial temperature, and even when a hot halo is able to develop in more massive galaxies there exist dense filaments that penetrate inside of the virial radius and deliver cold gas to the central galaxy. For galaxies up to ~L*, this cold accretion gas is responsible for the star formation in the disk at all times to the present. Even for galaxies at higher masses, cold flows dominate the growth of the disk at early times. Within this modified picture, galaxies are able to accrete a large mass of cold gas, with lower initial gas temperatures leading to shorter cooling times to reach the disk. Although star formation in the disk is mitigated by supernovae feedback, the short cooling times allow for the growth of stellar disks at higher redshifts than predicted by the standard model.Comment: accepted to Ap

Diagnosis of Helicobacter pylori by carbon-13 urea breath test using a portable mass spectrometer

CONTEXT: In the non-invasive detection of markers of disease, mass spectrometry is able to detect small quantities of volatile markers in exhaled air. However, the problem of size, expense and immobility of conventional mass spectrometry equipment has restricted its use. Now, a smaller, less expensive, portable quadrupole mass spectrometer system has been developed. Helicobacter pylori has been implicated in the development of chronic gastritis, gastric and duodenal ulcers and gastric cancer. OBJECTIVES: To compare the results obtained from the presence of H. pylori by a carbon-13 urea test using a portable quadrupole mass spectrometer system with those from a fixed mass spectrometer in a hospital-based clinical trial. METHODS: Following ethical approval, 45 patients attending a gastroenterology clinic at the Royal Liverpool University Hospital exhaled a breath sample into a Tedlar gas sampling bag. They then drank an orange juice containing urea radiolabelled with carbon and 30 min later gave a second breath sample. The carbon-13 content of both samples was measured using both quadrupole mass spectrometer systems. If the post-drink level exceeded the pre-drink level by 3% or more, a positive diagnosis for the presence of H. pylori was made. RESULTS: The findings were compared to the results using conventional isotope ratio mass spectrometry using a laboratory-based magnetic sector instrument off-site. The results showed agreement in 39 of the 45 patients. CONCLUSIONS: This study suggests that a portable quadrupole mass spectrometer is a potential alternative to the conventional centralised testing equipment. Future development of the portable quadrupole mass spectrometer to reduce further its size and cost is indicated, together with further work to validate this new equipment and to enhance its use in mass spectrometry diagnosis of other medical conditions

Developing a mobile audiometric sound booth application for Apple IOS devices

Hearing loss in Australian children, particularly those in rural and remote areas, is a growing health concern. Resultant deafness has significant impact on the educational and social development of such children. Whilst telehealth had provided other benefits for rural and remote areas, the absence of suitable testing equipment and associated healthcare specialists has meant that there is a gap in this area of child health that could be addressed using a mobile solution. This paper discusses the research and development of a mobile application for testing and diagnosis of hearing loss in children. It is unique in its ability to be able to function in uncontrolled test environments, and conforms to current hearing assessment standards. The application also produces an audiogram that can be immediately electronically transferred to the relevant healthcare provider. The application is specifically designed for young children to use and is designed to be used in collaboration with healthcare specialist audiologists and paediatricians. The prototype is currently undergoing testing at the Telethon Speech and Hearing institute, Perth, Western Australia. The results are expected to deliver crucial quantitative data to determine the accuracy of the application, as well as qualitative data from healthcare professionals and consumers

Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient

Using idealized N-body simulations of a Milky Way-sized disc galaxy, we qualitatively study how the metallicity distributions of the thin disc star particles are modified by the formation of the bar and spiral arm structures. The thin disc in our numerical experiments initially has a tight negative radial metallicity gradient and a constant vertical scaleheight. We show that the radial mixing of stars drives a positive vertical metallicity gradient in the thin disc. On the other hand, if the initial thin disc is flared, with vertical scaleheight increasing with galactocentric radius, the metal-poor stars, originally in the outer disc, become dominant in regions above the disc plane at every radii. This process can drive a negative vertical metallicity gradient, which is consistent with the current observed trend. This model mimics a scenario where the star-forming thin disc was flared in the outer region at earlier epochs. Our numerical experiment with an initial flared disc predicts that the negative vertical metallicity gradient of the mono-age relatively young thin disc population should be steeper in the inner disc, and the radial metallicity gradient of the mono-age population should be shallower at greater heights above the disc plane. We also predict that the metallicity distribution function of mono-age young thin disc populations above the disc plane would be more positively skewed in the inner disc compared to the outer disc

Preparing the sexual health workforce to deliver integrated services: is education the answer? A qualitative study exploring the impact of sexual health education on developing integrated policy and practice.

This study aimed to explore the ability of sexual health nurses working in the South West of England, to implement new learning within existing sexual health service delivery models. Drawing on Lipsky’s account of street-level bureaucracy to conceptualise policy implementation, the impact of workforce learning on the development of integrated services across this region of the United Kingdom was assessed. In order to achieve the United Nations’ goal of universal access to sexual health, it is essential for reproductive and sexual health, including HIV provision, to integrate into a single service. This integration requires a commitment to collaboration by service commissioners and an alignment of principles and values across sexual health and contraceptive services. UK health policy has embraced this holistic agenda but moves towards integrating historically separate clinical services, has presented significant workforce development challenges and influenced policy success. Employing a qualitative approach, the study included data from semi-structured telephone interviews and focus groups, and longitudinal data from pre- and post-intervention surveys, collected between September 2013 and September 2015. Data were collected from 88 nurses undertaking a workforce development programme and six of their service managers. Data were analysed using thematic analysis to identify consistent themes. Nurses confirmed the role of new learning in enabling them to negotiate the political landscape but expressed frustration at their lack of agency in the integration agenda, exposing a clear dichotomy between the intentions of policy and the reality of practice. Nevertheless, using high levels of professional judgement and discretion practitioners managed the incongruence between policy and practice in order to deliver integrated services in the interests of patients. Workforce education, while essential for the transition to the delivery of integrated services, was insufficient to fulfil the sexual health agenda without a strengthening of public health