Initial fate of fine ash and sulfur from large volcanic eruptions

Large volcanic eruptions emit huge amounts of sulfur and fine ash into the stratosphere. These products cause an impact on radiative processes, temperature and wind patterns. In simulations with a General Circulation Model including detailed aerosol microphysics, the relation between the impact of sulfur and fine ash is determined for different eruption strengths and locations, one in the tropics and one in high Northern latitudes. Fine ash with effective radii between 1 μm and 15 μm has a lifetime of several days only. Nevertheless, the strong absorption of shortwave and long-wave radiation causes additional heating and cooling of ±20 K/day and impacts the evolution of the volcanic cloud. Depending on the location of the volcanic eruption, transport direction changes due to the presence of fine ash, vortices develop and temperature anomalies at ground increase. The results show substantial impact on the local scale but only minor impact on the evolution of sulfate in the stratosphere in the month after the simulated eruptions

Preliminary site report for the 2005 ICDP-USGS deep corehole in the Chesapeake Bay impact crater

First report for the ICDP-USGS 1.7-km-deep corehole drilled into the central part of the Chesapeake Bay impact crater during 2005

Adsorption of benzene on Si(100) from first principles

Adsorption of benzene on the Si(100) surface is studied from first principles. We find that the most stable configuration is a tetra-$\sigma$-bonded structure characterized by one C-C double bond and four C-Si bonds. A similar structure, obtained by rotating the benzene molecule by 90 degrees, lies slightly higher in energy. However, rather narrow wells on the potential energy surface characterize these adsorption configurations. A benzene molecule impinging on the Si surface is most likely to be adsorbed in one of three different di-$\sigma$-bonded, metastable structures, characterized by two C-Si bonds, and eventually converts into the lowest-energy configurations. These results are consistent with recent experiments.Comment: 4 pages, RevTex, 2 PostScript gzipped figure

Trust and Credibility in Web-Based Health Information: A Review and Agenda for Future Research

Background: Online sources are becoming increasingly important in health information seeking, such that they may have a significant effect on health care decisions and outcomes. Hence, given the wide range of different sources of online health information from different organisations and individuals, it is important to understand how information seekers evaluate and select the sources that they use, and, more specifically how they assess their credibility and trustworthiness. Objectives: This article reviews empirical studies on trust and credibility in the use of online health information. The article seeks to present a profile of the research conducted on trust and credibility in online health information seeking, to identify the factors that impact judgements of trustworthiness and credibility, and to explore the role of demographic factors affecting trust formation. On this basis, it aims to identify the gaps in current knowledge and to propose an agenda for future research. Methods: A systematic literature review was conducted. Searches were conducted using a variety of combinations of the terms: online health information, trust, credibility, and their variants, in four multi-disciplinary and four health-oriented databases. Articles selected were published in English from 2000 onwards; this process generated 3827 unique records. After the application of exclusion criteria, this was reduced to a final dataset of 73 articles, which was analysed in full. Results: Interest in this topic has persisted over the last 15 years, with articles being published in medicine, social science and computer science, and focussing mostly on the USA and the UK. Documents in the dataset fell into three categories: those using trust or credibility as a dependent variable, those using trust or credibility as an independent variable, and studies of the demographic factors that influence the role of trust or credibility in online health information seeking. There is a consensus that in terms of website design, clear layout and design, interactive features and the authority of the owner have a positive effect on trust or credibility, whilst advertising has a negative effect. With regard to content features, authority of the author, ease of use and content have a positive effect on trust or credibility formation. Demographic factors influencing trust formation are age, gender and perceived health status. Conclusions: There is considerable scope for further research. This includes: increased clarity of the interaction between the variables associated with health information seeking; increased consistency on the measurement of trust and credibility; a greater focus on specific online health information sources; and, enhanced understanding of the impact of demographic variables on trust and credibility judgement

Toward Estimating Noise–Power–Distance Curves for Propeller-Powered Zero-Emission Hydrogen Aircraft

As part of the UK Research and Innovation project New Aviation, Propulsion, Knowledge and Innovation Network (NAPKIN), a high-level framework was developed for the assessment of the noise impact of the proposed regional-sized hydrogen-powered aircraft. This study consists of the methodology used to generate the industry-standard noise–power–distance (NPD) curves from individual component noise analysis, specifically propeller tonal noise. The model is based on an asymptotic analysis of a frequency domain propeller tonal noise model combined with a linear approximation, taking advantage of the logarithmic nature of noise. An error analysis on the linear approximation assumption proves that the relative error between predicted and actual values of the noise remains below 10% for appropriately chosen baseline points. Verification of the framework was achieved through a bench-marking procedure that compared predictions of departure NPD curves for current technology regional aircraft against published ones over a range of operational power settings. Finally, departure and approach NPD predictions for three of the NAPKIN hydrogen concept aircraft are presented. Concepts featuring a larger, slower-rotating propeller with an increased number of blades relative to the reference aircraft showed benefits over the reference aircraft, despite, in some cases, increases in maximum takeoff weight

Veterinary students' views on animal patiens and human clients, using Q methodology

Veterinarians serve two masters: animal patients and human clients. Both animal patients and human clients have legitimate interests, and conflicting moral claims may flow from these interests. Earlier research concludes that veterinary students are very much aware of the complex and often paradoxical relationship they have and will have with animals. In this article the views of veterinary students about their anticipated relationship with animal patients and human clients are studied. The main part of the article describes discourses of first-year and fourth-year students about their (future) relationship with animals and their caretakers, for which Q-methodology is used. At the end of the article, the discourses are related to the students' gender and their workplace preferences. © 2007 AAVMC

Laboratory Development

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Management of nystagmus in children : a review of the literature and current practice in UK specialist services

Nystagmus is an eye movement disorder characterised by abnormal, involuntary rhythmic oscillations of one or both eyes, initiated by a slow phase. It is not uncommon in the UK and regularly seen in paediatric ophthalmology and adult general/strabismus clinics. In some cases, it occurs in isolation, and in others, it occurs as part of a multisystem disorder, severe visual impairment or neurological disorder. Similarly, in some cases, visual acuity can be normal and in others can be severely degraded. Furthermore, the impact on vision goes well beyond static acuity alone, is rarely measured and may vary on a minute-to-minute, day-to-day or month-to-month basis. For these reasons, management of children with nystagmus in the UK is varied, and patients report hugely different experiences and investigations. In this review, we hope to shine a light on the current management of children with nystagmus across five specialist centres in the UK in order to present, for the first time, a consensus on investigation and clinical management

Forty years studying British politics : the decline of Anglo-America

The still present belief some 40 years ago that British politics was both exceptional and superior has been replaced by more theoretically sophisticated analyses based on a wider and more rigorously deployed range of research techniques, although historical analysis appropriately remains important. The American influence on the study of British politics has declined, but the European Union dimension has not been fully integrated. The study of interest groups has been in some respects a fading paradigm, but important questions related to democratic health have still to be addressed. Public administration has been supplanted by public policy, but economic policy remains under-studied. A key challenge for the future is the study of the management of expectations