683 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
Defect chemistry and vacancy concentration of luminescent europium doped ceria nanoparticles by solvothermal method
Pure phase and europium-doped ceria nanocrystals have been synthesized by a single step simple solvothermal process. Different spectroscopic, diffractive, and microscopic techniques were used to determine the morphology, size, crystal structure, and phase of all the samples. Electron energy loss spectroscopy (EELS) for elemental mapping confirmed that good solid solutions were formed and that the particles had a homogeneous distribution of europium. The defect chemistry was more complex than might be expected with the incorporation of each Eu3+ ion resulting in the production of an anion vacancy since the doping results in charge compensating (i.e., for Eu3+) anion vacancies as well as vacancies due to oxygen removal from the crystallite surface. Variations in nanoparticles dimension and lattice parameters were measured as a function of dopant concentrations and their variations explained. The band gap of the samples could be tailored by the doping. The doped samples were found to be luminescent due to the substitution of Ce4+ ions in the cubic symmetric lattice by the dopant ions. The thermal stability of the fluorescence properties was also investigated
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 ‘spirit of sport’ 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 ‘spirit of sport’. 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 ‘price’ 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
A field study in Benin to investigate the role of mosquitoes and other flying insects in the ecology of Mycobacterium ulcerans
Background Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. There is at present no clear understanding of the exact mode(s) of transmission of M. ulcerans. Populations affected by Buruli ulcer are those living close to humid and swampy zones. The disease is associated with the creation or the extension of swampy areas, such as construction of dams or lakes for the development of agriculture. Currently, it is supposed that insects (water bugs and mosquitoes) are host and vector of M. ulcerans. The role of water bugs was clearly demonstrated by several experimental and environmental studies. However, no definitive conclusion can yet be drawn concerning the precise importance of this route of transmission. Concerning the mosquitoes, DNA was detected only in mosquitoes collected in Australia, and their role as host/vector was never studied by experimental approaches. Surprisingly, no specific study was conducted in Africa. In this context, the objective of this study was to investigate the role of mosquitoes (larvae and adults) and other flying insects in ecology of M. ulcerans. This study was conducted in a highly endemic area of Benin. Methodology/Principal Findings Mosquitoes (adults and larvae) were collected over one year, in Buruli ulcer endemic in Benin. In parallel, to monitor the presence of M. ulcerans in environment, aquatic insects were sampled. QPCR was used to detected M. ulcerans DNA. DNA of M. ulcerans was detected in around 8.7% of aquatic insects but never in mosquitoes (larvae or adults) or in other flying insects. Conclusion/Significance This study suggested that the mosquitoes don't play a pivotal role in the ecology and transmission of M. ulcerans in the studied endemic areas. However, the role of mosquitoes cannot be excluded and, we can reasonably suppose that several routes of transmission of M. ulcerans are possible through the world
One place doesn't fit all: improving the effectiveness of sustainability standards by accounting for place
Includes bibliographical references (pages 8-10).The growing interest in incentivizing sustainable agricultural practices is supported by a large network of voluntary production standards, which aim to offer farmers and ranchers increased value for their product in support of reduced environmental impact. To be effective with producers and consumers alike, these standards must be both credible and broadly recognizable, and thus are typically highly generalizable. However, the environmental impact of agriculture is strongly place-based and varies considerably due to complex biophysical, socio-cultural, and management-based factors, even within a given sector in a particular region. We suggest that this contradiction between the placeless generality of standards and the placed-ness of agriculture renders many sustainability standards ineffective. In this policy and practice review, we examine this contradiction through the lens of beef production, with a focus on an ongoing regional food purchasing effort in Denver, Colorado, USA. We review the idea of place in the context of agricultural sustainability, drawing on life cycle analysis and diverse literature to find that recognition of place-specific circumstances is essential to understanding environmental impact and improving outcomes. We then examine the case of the Good Food Purchasing Program (GFPP), a broad set of food-purchasing standards currently being implemented for institutional purchasing in Denver. The GFPP was created through a lengthy stakeholder-inclusive process for use in Los Angeles, California, USA, and has since been applied to many cities across the country. The difference between Los Angeles' process and that of applying the result of Los Angeles' process to Denver is instructive, and emblematic of the flaws of generalizable sustainability standards themselves. We then describe the essential elements of a place-based approach to agricultural sustainability standards, pointing toward a democratic, process-based, and outcome-oriented strategy that results in standards that enable rather than hinder the creativity of both producers and consumers. Though prescription is anathema to our approach, we close by offering a starting point for the development of standards for beef production in Colorado that respect the work of people in place
Size and space controlled hexagonal arrays of superparamagnetic iron oxide nanodots: magnetic studies and application
Highly dense hexagonally arranged iron oxide nanodots array were fabricated using PS-b-PEO self-assembled patterns. The copolymer molecular weight, composition and choice of annealing solvent/s allows dimensional and structural control of the nanopatterns at large scale. A mechanism is proposed to create scaffolds through degradation and/or modification of cylindrical domains. A methodology based on selective metal ion inclusion and subsequent processing was used to create iron oxide nanodots array. The nanodots have uniform size and shape and their placement mimics the original self-assembled nanopatterns. For the first time these precisely defined and size selective systems of ordered nanodots allow careful investigation of magnetic properties in dimensions from 50 nm to 10 nm, which delineate the nanodots are superparamagnetic, well-isolated and size monodispersed. This diameter/spacing controlled iron oxide nanodots systems were demonstrated as a resistant mask over silicon to fabricate densely packed, identical ordered, high aspect ratio silicon nanopillars and nanowire features
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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 ‘more-than-food’ through analyses of the visceral nature of eating and politics and the vital (re)materializations of food’s cultural geographies. Visceral food geographies illuminate what I call the ‘contingent relationalities’ of food in the critical evaluation of the indeterminate, situated politics of ‘feeling food’ 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 food’s vital materialisms opens up investigation into the practices of the ‘makings’ 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, ‘post-relational’ 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 rise of the citizen author: Writing within social media
The concept of the citizen author is defined and explored within the publishing industry. In order to understand what positions the citizen author currently, and potentially could, hold it begins with a historical view of their rise, including concepts of their eighteenth century antecedents. But the focus of this research is on their growth alongside that of social media platforms. This allows for drawing out relationships between genre fiction, publishers, and the citizen author, which provides a more full understanding of the power dynamics involved when publishers, social media, and the citizen authors mix in the current industry climate.N/
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