27 research outputs found
Dynamics and Radiation of Young Type-Ia Supernova Remnants: Important Physical Processes
We examine and analyze the physical processes that should be taken into
account when modeling young type-Ia SNRs, with ages of several hundred years.
It is shown, that energy losses in the metal-rich ejecta can be essential for
remnants already at this stage of evolution. The influence of electron thermal
conduction and the rate of the energy exchange between electrons and ions on
the temperature distribution and the X-radiation from such remnants is studied.
The data for Tycho SNR from the XMM-Newton X-ray telescope have been employed
for the comparison of calculations with observations.Comment: 19 pages, 8 figure
Three pillars of sustainability: in search of conceptual origins
The three-pillar conception of (social, economic and environmental) sustainability, commonly represented by three intersecting circles with overall sustainability at the centre, has become ubiquitous. With a view of identifying the genesis and theoretical foundations of this conception, this paper reviews and discusses relevant historical sustainability literature. From this we find that there is no single point of origin of this three-pillar conception, but rather a gradual emergence from various critiques in the early academic literature of the economic status quo from both social and ecological perspectives on the one hand, and the quest to reconcile economic growth as a solution to social and ecological problems on the part of the United Nations on the other. The popular three circles diagram appears to have been first presented by Barbier (Environ Conserv 14:101, doi: 10.1017/s0376892900011449, 1987), albeit purposed towards developing nations with foci which differ from modern interpretations. The conceptualisation of three pillars seems to predate this, however. Nowhere have we found a theoretically rigorous description of the three pillars. This is thought to be in part due to the nature of the sustainability discourse arising from broadly different schools of thought historically. The absence of such a theoretically solid conception frustrates approaches towards a theoretically rigorous operationalisation of ‘sustainability’
Circadian rhythm of activity of the caudate nucleus in cats and its sensitivity to psychotropic drugs
Effect of parachlorophenylalanine and 5-hydroxytryptophan on the caudate nucleus in cats
Effect of melatonin and pinealectomy on the state of the rat liver mono-oxygenase system
Changes in neuronal trace responses of the sensomotor cortex and putamen induced by haloperidol
Dematerialization through electronic media?
While the traditional roles of the computer as a machine for scientific calculations, text editing, and graphic design are still significant, computers are increasingly perceived as means of accessing information and interacting with other people – i.e., as electronic media. The aim of this chapter is to analyze digital electronic media and their effects on environmental sustainability. Two fields of application are addressed: electronic media that may replace or augment traditional print media such as newspapers or magazines, and videoconferencing as a potential substitute for traveling to a face-to-face meeting or conference. In both cases, the environmental costs of the electronic media are compared to those of their conventional counterparts. The examples show that electronic media can represent an energy-efficient alternative to traditional activities such as long-distance travel. But they can also be added on top of existing activities instead of replacing them. In such cases, a net increase in the environmental impact results. The availability of small, energy-efficient devices being used as electronic media does not guarantee dematerialization. The overall resource use and emissions throughout the life cycle of the media product systems and, more importantly, at the macro level of total global production and consumption need to be considered. To achieve the dematerialization potential of new electronic media solutions, their efficiency needs to be combined with sufficiency; thus additional measures are necessary to turn the dematerialization potential of electronic media into environmental relief