126,263 research outputs found
Artificial broadening of the high-energy end of electron spectrum in supernova remnants
The observed spectrum of a supernova remnant (SNR) is a superposition of many
``local'' spectra emitted by regions of SNRs that are under different physical
conditions. The question remains as to whether the broadening of the
high-energy end of the observed nonthermal spectrum of SNRs, like in G347.3-0.5
and SN 1006, can be an artifact of observations or it is a consequence of the
microphysics involved in the acceleration process. In this note we study the
influence of parameters variations (inside the volume and over the surface of
SNR) on the shape of the high-energy end of the synchrotron (and also inverse
Compton) spectrum. We consider three possibilities for these parameter
variations: i) gradients downstream of the shock with constant maximum energy
of the accelerated electrons and the potential variation in time of the
injection efficiency, ii) then we add the possibility of the maximum energy
depending on time, and finally iii) the possible obliquity dependences of
maximum energy and injection efficiency. It is shown that gradients of density
and magnetic field strength downstream of the shock are ineffective in
modifying the shape of the synchrotron spectrum, even if an SNR evolves in the
nonuniform interstellar medium and/or the injection efficiency varies in time.
The time dependence of the maximum energy of the electrons accelerated by the
shock is also not able to make the observed spectrum much broader. The only
possibility of producing considerable broadening in the spectrum is the
variation in the maximum energy of electrons over the surface of SNR. In such a
case, the obliquity dependence of the injection efficiency also affects the
shape of the spectrum, but its role is less significant.Comment: 6 pages, 4 figures, A&A accepte
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Sustainable Gastronomy: the Environmental Impacts of How We Cook Now and How the âSustainable Dietsâ Agenda Might Shape How We Cook in the Future?
The 2019 Eat-Lancet report has proposed a global healthy sustainable diet, which would provide not only for human health but also sustain a healthy planet. The main recommendations are to increase consumption of healthy foods (such as vegetables, fruits, whole grains, legumes, and nuts), and a decrease in consumption of unhealthy foods (such as red meat, sugar, and refined grains). A critique of the EAT-Lancet diet is that it lacks consideration of local and traditional diets, food ways or systems of production, and the report has limited suggestions for how a global healthy sustainable diet could be implemented (Edman et al., 2019; Jonas, 2019; Torjesen, 2019). This paper firstly explores the sustainability impacts of cooking food, and how different foods have different environmental impacts from production, consumption, and cooking. It reports on a 2019 survey of cooking methods and habits in the UK, Australia and USA, examining how these different nationsâ unique culinary and cooking habits lead to different environmental impacts. This paper then examines what dietary shifts are being recommended by current academic literature, and how these dietary shifts may change the methods of cooking in the future
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Towards reframing professional expert support
The paper addresses practical ways of reconfiguring professional expertise in development practice in moving away from the expert as a technocrat. Two projects associated with managing natural resource dilemmas suggest an alternative way of framing intervention involving professional experts providing a more appropriate collaborative learning space for development practice. The paper describes the heuristic devices generated by each project as helpful in bringing out dialectic tensions between practice and understanding, and between systems of interest and situations of interest (or situated problems). Firstly, SLIM (social learning for the integrated management and sustainable use of water at catchment scale) - a European Framework Programme 5 project - exemplifies social learning as a measure of sustainable development. The heuristic illustrates the dependence of sustainability on changes in practice and understanding amongst professionals and other stakeholders as part of concerted - rather than merely individual or even collective - action. Secondly, ECOSENSUS (Electronic/Ecological Collaborative Sensemaking Support System) - a Guyana focused intervention involving several UK universities in collaboration with the University of Guyana and Amerindian community representatives from the North Rupununi wetlands - builds on the SLIM heuristic in supporting the development of practice. Additionally, the ECOSENSUS heuristic provides conceptual space for the interaction between conceptual constructs of distributed stakeholders (that is, systems thinking) including those with professional expertise, and the actual context of intervention (the situated problem). Both SLIM and ECOSENSUS provide heuristics for process-orientated management enabling more meaningful and purposeful interaction between professional/ technical experts and other stakeholders, as an alternative to conventional project-orientated management intervention. An alternative framing may help to steer practice away from the apoliticised comforting linearity of professionalised systematic project management towards more constructive systemic endeavours involving multiple stakeholders
A Faster Tableau for CTL*
There have been several recent suggestions for tableau systems for deciding
satisfiability in the practically important branching time temporal logic known
as CTL*. In this paper we present a streamlined and more traditional tableau
approach built upon the author's earlier theoretical work.
Soundness and completeness results are proved. A prototype implementation
demonstrates the significantly improved performance of the new approach on a
range of test formulas. We also see that it compares favourably to state of the
art, game and automata based decision procedures.Comment: In Proceedings GandALF 2013, arXiv:1307.416
Philosophy with children : helping designers cooperate with children
Engaging children in design through in-depth interviews is coming to prominence in the IDC community, which increasingly engages with issues about understanding the children's world. To date, research in this area has primarily focused on engaging children using techniques somehow similar to adult-techniques (moodboards, brainstorming, laddering,...). However, questioning or interviewing children is fraught with difficulties. The proposed workshop seeks to explore where and how a philosophy with children methodology can be adapted for design, exploring themes such as Socratic Attitudes, wondering, and question types. This workshop aims to build an interdisciplinary community of researchers, designers, and practitioners to share and discuss their work and experiences
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Equity-focused developmental evaluation using critical systems thinking
Developmental evaluation questions the ethical basis of an intervention in terms of whether itâs âdoing the right thingâ rather than merely âdoing things rightâ. But developmental evaluation invites a space for exploring not only ethical but also political issues associated particularly with equity-focused evaluations. Drawing on ideas from critical systems thinking (CST) and critical systems heuristics, an evaluation framework with a pro-equity focus is suggested. The framework addresses issues of complex interrelationships, invites theory of change associated with philosophical ethics, and provides a means of surfacing, and potentially transforming, debilitating relations of power in a complex evaluand. A case study of the long-standing Narmada project in India is used to illustrate the workings of proposed framework. The paper describes how the underpinning methodological ideas of CST incorporating triple-loop learning can enhance the practice of developmental evaluation
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Conversations about creativity and chronic illness II: Textile artists coping with long-term health problems reflect on the creative process
This qualitative study explored the origins of interest in textile arts among a group of women living with long-term health problems. The part that illness played in motivating engagement in creative arts was of particular concern. Twenty four women were interviewed, aged between 29-72 years. Most were hobbyists and but the sample included some publicly acclaimed textile artists. A minority had engaged in art continuously since their earlier years. Most of the women had discovered (or re-discovered) textile arts, in middle and later life. Several factors facilitated this. The narratives indicated that the womenâs pre-existing resilient personality as well as extensive support structures may have encouraged a reflective attitude and a problem-solving approach to living with illness. The experience of biographical disruption, stemming from the crisis of illness, dissatisfaction with unproductive time and a growing need for self-fulfilment, appeared to create a search for a meaningful occupation. The discovery of textile art as a meaningful occupation (as opposed to other ways of living with illness) appeared to be encouraged by early role models, enjoyment of art at school, the discovery that adult personal and professional interests could be expressed through artwork, and chance events. Textile art at school appeared to provide a form of âcultural capitalâ for these women, who returned to this art medium and the skills learned earlier, when crisis occurred. The findings indicate that a negative event such as illness may have life-enhancing effects. Rehabilitation specialists might focus more on the arts as a resource for adults living with illness
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