1,416 research outputs found
Supernova remnants' interactions with the inter-stellar medium
All-sky data at a number of different wavelengths are used to examine the Giant Radio Loops. The x-ray emission of Loop I is modelled as being due to a Supernova Remnant (SNR) that has evolved in a hot, homogeneous, quasi-isotropic medium. The shock is found to weaken towards higher latitudes, and this is attributed to an increase in the ambient gas temperature away from the galactic plane. Other evolutionary possibilities are examined. Radio spectral index maps from 38 to 1420MHz of the northern celestial hemisphere are produced, and the spectra of loops I and III are modelled on the assumption that the energy distribution of electrons accelerated in the shocks will have an upper energy cut-off due to the finite age of the remnants. It is found that the steepening spectra can be fitted by such a model. The electron distribution below the cut-off of order l0GeV is found to fit best if a flatter spectrum than predicted by simple shock theory is assumed. The idea that shocks. Interacting with clouds can explain this flatter spectrum and enhance the soft x-ray emission is put forward as an alternative evolutionary possibility, bringing together the two separate x-ray and radio emission mechanisms. Other galactic SNR are examined to support this idea, including a newly discovered SNR that exists inside the error circle of the COS-B source 2CG342-02. Although this remnant’s association with the γ-ray source cannot be excluded, no firm evidence is found to identify it as the source
Nitrate pollution from horticultural production systems : tools for policy and advice from field to catchment scales
The implementation of the Nitrates Directive has imposed a requirement to restrict N fertiliser and manuring practices on farms across the EU in order to reduce nitrate losses to water. These requirements have since been extended by the more demanding Water Framework Directive, which broadens the focus from the control of farm practices to a consideration of the impacts of pollutants from all sources on water quality at a catchment or larger scale. Together, these Directives set limits for water quality, and identify general strategies for how these might be achieved. However, it is the responsibility of policy makers in each Nation State to design the details of the management practices and environmental protection measures required to meet the objectives of the legislation, to ensure they are appropriate for their specific types of land use and climate. This paper describes various modelling tools for comparing different cropping and land use strategies, and illustrates with examples how they can inform policy makers about the environmental benefits of changing management practices and how to prioritise them. The results can help to provide the specific advice on N fertiliser and land use management required by farmers and growers at a field scale, and by environmental managers at a catchment or larger scale. A further example of how results from multiple catchments can be up-scaled and compared using Geographic Information Systems is also outlined
Ordered Array of Single Au Adatoms with Remarkable Thermal Stability: Au/Fe3O4(001)
We present a Scanning Tunneling Microscopy (STM) investigation of gold
deposited at the magnetite Fe3O4(001) surface at room temperature. This surface
forms a reconstruction with (\surd2\times\surd2)R45{\deg} symmetry, where pairs
of Fe and neighboring O ions are slightly displaced laterally, forming
undulating rows with 'narrow' and 'wide' adsorption sites. At fractional
monolayer coverages, single Au adatoms adsorb exclusively at the narrow sites,
with no significant sintering up to annealing temperatures of 400 {\deg}C. The
strong preference for this site is possibly related to charge and orbital
ordering within the first subsurface layer of the reconstructed Fe3O4(001)
surface. Because of their high thermal stability, the ordered Au atoms at
Fe3O4(001)- (\surd2\times\surd2)R45{\deg} could provide useful for probing the
chemical reactivity of single atomic species.Comment: Duplicate entry, newer version at 1205.0915.
http://arxiv.org/abs/1205.091
The Socratic Method in the Introductory PR Course: An Alternative Pedagogy
In the recent past several educators and practitioners have advocated the use of a Socratic dialogue or case method to teach public relations principles. Reported here are the results of an empirical study comparing student reactions to and perceptions of learning in introductory public relations courses using a traditional lecture format and a Socratic approach. The independent variables in this study are lecture and Socratic teaching methods. It was hypothesized that compared to students in a traditional course, students in the Socratic course would: (1) retain more factual information about public relations, (2) feel more confident in their knowledge and skills needed to work in public relations, (3) report more opportunity to practice critical thinking, (4) report more opportunity to practice problem solving skills, (5) report greater aspiration to work in public relations, and (6) report higher levels of course satisfaction. For four of the six research questions examined, there were small differences between students who received traditional and Socratic instruction. These differences were in the direction expected but were not statistically significant. There were significant differences in the two groups showing that students who received the Socratic instruction reported more opportunities in practicing their critical thinking ability, and ability to solve practical public relations problems
Redistribution in Aegean Palatial Societies. Redistributive Economies from a Theoretical and Cross-Cultural Perspective
In this article, we address the historical question of why Aegean Bronze Age economies are characterized as redistributive systems and whether it is appropriate to continue to describe them as such. We argue that characterizing the political economies of the Aegean as redistributive is inaccurate and misleading. Instead, we suggest it is more fruitful to describe how specific prehistoric social institutions were used to organize and allocate goods and services and thereby to study how political and economic systems interacted with one another. By examining how Aegean social institutions were constituted and changed over time, we will be in a position to use the prehistoric Aegean to develop and refine general models of political economy
Redistribution in Aegean Palatial Societies. Introduction: Why Redistribution?
This collection of papers explores the role of redistribution
in Minoan and Mycenaean economies
Demonstrating Interactive Machine Learning Tools for Rapid Prototyping of Gestural Instruments in the Browser
These demonstrations will allow visitors to prototype gestural, interactive musical instruments in the browser. Different browser based synthesisers can be controlled by either a Leap Motion sensor or a Myo armband. The visitor will be able to use an interactive machine learning toolkit to quickly and iteratively explore different interaction possibilities.
The demonstrations show how interactive, browser-based machine learning tools can be used to rapidly prototype gestural controllers for audio.
These demonstrations showcase RapidLib, a browser based machine learning library developed through the RAPID-MIX project
NMR analysis of Nile Blue (C. I. Basic Blue 12) and Thionine (C. I. 52000) in solution
The dyes Nile Blue (C. I. Basic Blue 12, NB) and Thionine (C. I. 52000, TH) were examined in both ionic and neutral forms in different solvents using NMR and UV-visible Spectroscopy to firmly establish the structures of the molecules and to assess the nature and extent of their aggregating characteristics. 1H and 13C NMR assignments and chemical shift data were used along with (for NB) nuclear Overhauser effect information enabling a structure for self-assembly to be proposed. In both cases these data were supplemented with variable temperature, dilution and diffusion-based experimental results using 1H NMR spectroscopy thereby enabling the extended aggregate structures to be assessed in terms of the relative strength of self-association and the extent to which extended aggregates could form. Full and detailed solution phase NMR analysis of such dyes, especially the two studied in this context, have either not been widely reported or have not been studied to the depth presented here. The data and their interpretation form an important addition to the analysis of this class of dye compounds and provide additional insight into the effects of self-assembly on the behaviour of such molecules in various solution-phase environments
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