450 research outputs found
Unified Models of Molecular Emission from Class 0 Protostellar Outflow Sources
Low mass star-forming regions are more complex than the simple spherically
symmetric approximation that is often assumed. We apply a more realistic
infall/outflow physical model to molecular/continuum observations of three late
Class 0 protostellar sources with the aims of (a) proving the applicability of
a single physical model for all three sources, and (b) deriving physical
parameters for the molecular gas component in each of the sources.
We have observed several molecular species in multiple rotational
transitions. The observed line profiles were modelled in the context of a
dynamical model which incorporates infall and bipolar outflows, using a three
dimensional radiative transfer code. This results in constraints on the
physical parameters and chemical abundances in each source.
Self-consistent fits to each source are obtained. We constrain the
characteristics of the molecular gas in the envelopes as well as in the
molecular outflows. We find that the molecular gas abundances in the infalling
envelope are reduced, presumably due to freeze-out, whilst the abundances in
the molecular outflows are enhanced, presumably due to dynamical activity.
Despite the fact that the line profiles show significant source-to-source
variation, which primarily derives from variations in the outflow viewing
angle, the physical parameters of the gas are found to be similar in each core.Comment: MNRAS 12 pages, 16 figure
The spirit of sport: the case for criminalisation of doping in the UK
This article examines public perceptions of doping in sport, critically evaluates the effectiveness of current anti-doping sanctions and proposes the criminalisation of doping in sport in the UK as part of a growing global movement towards such criminalisation at national level. Criminalising doping is advanced on two main grounds: as a stigmatic deterrent and as a form of retributive punishment enforced through the criminal justice system. The âspirit of sportâ defined by the World Anti-Doping Agency (WADA) as being based on the values of ethics, health and fair-play is identified as being undermined by the ineffectiveness of existing anti-doping policy in the current climate of doping revelations, and is assessed as relevant to public perceptions and the future of sport as a whole. The harm-reductionist approach permitting the use of certain performance enhancing drugs (PEDs) is considered as an alternative to anti-doping, taking into account athlete psychology, the problems encountered in containing doping in sport through anti-doping measures and the effect of these difficulties on the âspirit of sportâ. This approach is dismissed in favour of criminalising doping in sport based on the offence of fraud. It will be argued that the criminalisation of doping could act as a greater deterrent than existing sanctions imposed by International Federations, and, when used in conjunction with those sanctions, will raise the overall âpriceâ of doping. The revelations of corruption within the existing system of self-governance within sport have contributed to a disbelieving public and it will be argued that the criminalisation of doping in sport could assist in satisfying the public that justice is being done and in turn achieve greater belief in the truth of athletic performances
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Food geographies I: relational foodscapes and the busy-ness of being more-than-food
The study of foodscapes has spread throughout geography at the same time as food scholarship has spearheaded post-disciplinary research. This report argues that geographers have taken to post-disciplinarity to explore the ways that food is âmore-than-foodâ through analyses of the visceral nature of eating and politics and the vital (re)materializations of foodâs cultural geographies. Visceral food geographies illuminate what I call the âcontingent relationalitiesâ of food in the critical evaluation of the indeterminate, situated politics of âfeeling foodâ and those of the embodied collectivities of obesity. Questions remain, however, about how a visceral framework might be deployed for broader critiques within foodscapes and the study of human geography. The study of foodâs vital materialisms opens up investigation into the practices of the âmakingsâ of meat, food waste and eating networks. Analysis of affect, embodiment and cultural practices is central to these theorizations and suggests consideration of the multiple materialisms of food, space and eating. There is, I contend, in the more radical, âpost-relationalâ approaches to food, the need for a note of caution. Exuberant claims for the ontological, vital agency of food should be tempered by, or at least run parallel to, critical questions of the real politik of political and practical agency in light of recent struggles over austerity, food poverty and food justice
CO abundances in a protostellar cloud: freeze-out and desorption in the envelope and outflow of L483
CO isotopes are able to probe the different components in protostellar
clouds. These components, core, envelope and outflow have distinct physical
conditions and sometimes more than one component contributes to the observed
line profile. In this study we determine how CO isotope abundances are altered
by the physical conditions in the different components. We use a 3D molecular
line transport code to simulate the emission of four CO isotopomers, 12CO
J=2-1, 13CO J=2-1, C18O J=2-1 and C17O J=2-1 from the Class 0/1 object L483,
which contains a cold quiescent core, an infalling envelope and a clear
outflow. Our models replicate JCMT (James Clerk Maxwell Telescope) line
observations with the inclusion of freeze-out, a density profile and infall.
Our model profiles of 12CO and 13CO have a large linewidth due to a high
velocity jet. These profiles replicate the process of more abundant material
being susceptible to a jet. C18O and C17O do not display such a large linewidth
as they trace denser quiescent material deep in the cloud.Comment: 9 figures, 13 pages, 2 table
The Different Structures of the Two Classes of Starless Cores
We describe a model for the thermal and dynamical equilibrium of starless
cores that includes the radiative transfer of the gas and dust and simple CO
chemistry. The model shows that the structure and behavior of the cores is
significantly different depending on whether the central density is either
above or below about 10^5 cm-3. This density is significant as the critical
density for gas cooling by gas-dust collisions and also as the critical density
for dynamical stability, given the typical properties of the starless cores.
The starless cores thus divide into two classes that we refer to as thermally
super-critical and thermally sub-critical.This two-class distinction allows an
improved interpretation of the different observational data of starless cores
within a single model.Comment: ApJ in pres
Global and local environmental changes as drivers of Buruli ulcer emergence
International audienceMany emerging infectious diseases are caused by generalist pathogens that infect and transmit via multiple host species with multiple dissemination routes, thus confounding the understanding of pathogen transmission pathways from wildlife reservoirs to humans. The emergence of these pathogens in human populations has frequently been associated with global changes, such as socio-economic, climate or biodiversity modifications, by allowing generalist pathogens to invade and persist in new ecological niches, infect new host species, and thus change the nature of transmission pathways. Using the case of Buruli ulcer disease, we review how land-use changes, climatic patterns and biodiversity alterations contribute to disease emergence in many parts of the world. Here we clearly show that Mycobacterium ulcerans is an environmental pathogen characterized by multi-host transmission dynamics and that its infectious pathways to humans rely on the local effects of global environmental changes. We show that the interplay between habitat changes (for example, deforestation and agricultural land-use changes) and climatic patterns (for example, rainfall events), applied in a local context, can lead to abiotic environmental changes and functional changes in local biodiversity that favor the pathogenâs prevalence in the environment and may explain disease emergence
Designing a web-application to support home-based care of childhood CKD stages 3-5: Qualitative study of family and professional preferences
Background: There is a lack of online, evidence-based information and resources to support home-based care of childhood CKD stages 3-5. Methods. Qualitative interviews were undertaken with parents, patients and professionals to explore their views on content of the proposed online parent information and support (OPIS) web-application. Data were analysed using Framework Analysis, guided by the concept of Self-efficacy. Results: 32 parents, 26 patients and 12 professionals were interviewed. All groups wanted an application that explains, demonstrates, and enables parental clinical care-giving, with condition-specific, continously available, reliable, accessible material and a closed communication system to enable contact between families living with CKD. Professionals advocated a regularly updated application to empower parents to make informed health-care decisions. To address these requirements, key web-application components were defined as: (i) Clinical care-giving support (information on treatment regimens, video-learning tools, condition-specific cartoons/puzzles, and a question and answer area) and (ii) Psychosocial support for care-giving (social-networking, case studies, managing stress, and enhancing families' health-care experiences). Conclusions: Developing a web-application that meets parents' information and support needs will maximise its utility, thereby augmenting parents' self-efficacy for CKD caregiving, and optimising outcomes. Self-efficacy theory provides a schema for how parents' self-efficacy beliefs about management of their child's CKD could potentially be promoted by OPIS. © 2014 Swallow et al.; licensee BioMed Central Ltd
Connecting urban food plans to the countryside: leveraging Denver's food vision to explore meaningful rural-urban linkages
Includes bibliographical references (pages 14-18).Cities are increasingly turning to food policy plans to support goals related to food access, food security, the environment, and economic development. This paper investigates ways that rural farmers, communities, and economies can both support and be supported by metropolitan food-focused initiatives. Specifically, our research question asked what opportunities and barriers exist to developing food policies that support urban food goals, particularly related to local procurement, as well as rural economic development. To address this question, we described and analyzed a meeting of urban stakeholders and larger-scale rural producers related to Coloradoâs Denver Food Vision and Plan. We documented and explored âfindingsâ gleaned from a supply chain diagraming and data compilation process that were then used to inform an event that brought together diverse supply chain partners. Three findings stand out. First, facilitating dialog between urban food policymakers and rural producers to understand potential tensions, mitigate such tensions, and capitalize on opportunities is essential. Second, perceptions and expectations surrounding âgood foodâ are nuancedâa timely finding given the number of preferred procurement programs emerging across the county. Third, critical evaluation is needed across a diverse set of value chain strategies (e.g., conventional and alternative distribution) if food policy intends to support heterogeneous producers, their communities, and urban food policy goals
Aerodynamic investigations of ventilated brake discs.
The heat dissipation and performance of a ventilated brake disc strongly depends
on the aerodynamic characteristics of the flow through the rotor passages. The
aim of this investigation was to provide an improved understanding of ventilated
brake rotor flow phenomena, with a view to improving heat dissipation, as well
as providing a measurement data set for validation of computational fluid
dynamics methods. The flow fields at the exit of four different brake rotor
geometries, rotated in free air, were measured using a five-hole pressure probe
and a hot-wire anemometry system. The principal measurements were taken using
two-component hot-wire techniques and were used to determine mean and unsteady
flow characteristics at the exit of the brake rotors. Using phase-locked data
processing, it was possible to reveal the spatial and temporal flow variation
within individual rotor passages. The effects of disc geometry and rotational
speed on the mean flow, passage turbulence intensity, and mass flow were
determined. The rotor exit jet and wake flow were clearly observed as
characterized by the passage geometry as well as definite regions of high and
low turbulence. The aerodynamic flow characteristics were found to be reasonably
independent of rotational speed but highly dependent upon rotor geometry
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