14,507 research outputs found
Endgame for the West in Afghanistan? Explaining the Decline in Support for the War in Afghanistan in the United States, Great Britain, Canada, Australia, France and Germany
Domestic public opinion is frequently and correctly described as a crucial battlefront in the war in Afghanistan. Commentary by media and political figures currently notes not only the falling support for the war in the United States but also in many of its key allies in Europe and elsewhere, making it all the more difficult for the Obama administration to secure the help it believes it needs to bring the war to a successful conclusion. This study is an extensive examination of the determinants of domestic support for and opposition to the war in Afghanistan in the United States and in five of its key allies--the United Kingdom, France, Germany, Canada, and Australia. Tracing the trajectory of public opinion on the war from the original invasion in 2001 to the fall of 2009, this paper concludes that the combination of mounting casualties with a declining belief that the war could be won by the Coalition is the key factor driving the drop in support. Other factors, such as the deployment of numerous and shifting rationales by the political leadership in various countries, and the breakdown of elite consensus have played important but secondary roles in this process.https://press.armywarcollege.edu/monographs/1345/thumbnail.jp
Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes
The rock record contains a rich variety of sedimentary surface textures on siliciclastic sandstone, siltstone and mudstone bedding planes. In recent years, an increasing number of these textures have been attributed to surficial microbial mats at the time of deposition, resulting in their classification as microbially induced sedimentary structures, or MISS. Research into MISS has developed at a rapid rate, resulting in a number of misconceptions in the literature. Here, we attempt to rectify these MISS misunderstandings. The first part of this paper surveys the stratigraphic and environmental range of reported MISS, revealing that contrary to popular belief there are more reported MISS-bearing rock units of Phanerozoic than Precambrian age. Furthermore, MISS exhibit a pan-environmental and almost continuous record since the Archean. Claims for the stratigraphic restriction of MISS to intervals prior to the evolution of grazing organisms or after mass extinction events, as well as claims for the environmental restriction of MISS, appear to result from sampling bias. In the second part of the paper we suggest that raised awareness of MISS has come at the cost of a decreasing appreciation of abiotic processes that may create morphologically similar features. By introducing the umbrella term ‘sedimentary surface textures’, of which MISS are one subset, we suggest a practical methodology for classifying such structures in the geological record. We illustrate how elucidating the formative mechanisms of ancient sedimentary surface textures usually requires consideration of a suite of sedimentological evidence from surrounding strata. Resultant interpretations, microbial or non-microbial, should be couched within a reasonable degree of uncertainty. This approach recognizes that morphological similarity alone does not constitute scientific proof of a common origin, and reinstates a passive descriptive terminology for sedimentary surface textures that cannot be achieved with the current MISS lexicon. It is hoped that this new terminology will reduce the number of overly sensational and misleading claims of MISS occurrence, and permit the means to practically separate initial observation from interpretation. Furthermore, this methodology offers a scientific approach that appreciates the low likelihood of conclusively identifying microbial structures from visual appearance alone, informing the search for true MISS in Earth's geological record and potentially on other planetary bodies such as Mars.Instances of sedimentary surface textures in the field were identified coincidentally during multiple seasons of varied field investigations primarily funded for NSD by a variety of organisations including a George Frederic Matthew Research Grant from the New Brunswick Museum for 2012, and a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada to MRG. AGL is supported by the Natural Environment Research Council [grant number NE/L011409/1].This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.earscirev.2016.01.00
An analytic approximation to the Diffusion Coefficient for the periodic Lorentz Gas
An approximate stochastic model for the topological dynamics of the periodic
triangular Lorentz gas is constructed. The model, together with an extremum
principle, is used to find a closed form approximation to the diffusion
coefficient as a function of the lattice spacing. This approximation is
superior to the popular Machta and Zwanzig result and agrees well with a range
of numerical estimates.Comment: 13 pages, 4 figure
Effect of spirometry on intra-thoracic pressures
Due to the high intra-thoracic pressures associated with forced vital capacity manoeuvres, spirometry is contraindicated for vulnerable patients. However, the typical pressure response to spirometry has not been reported. Eight healthy, recreationally-active men performed spirometry while oesophageal pressure was recorded using a latex balloon-tipped catheter. Peak oesophageal pressure during inspiration was - 47 ± 9 cmH O (37 ± 10% of maximal inspiratory pressure), while peak oesophageal pressure during forced expiration was 102 ± 34 cmH O (75 ± 17% of maximal expiratory pressure). The deleterious consequences of spirometry might be associated with intra-thoracic pressures that approach maximal values during forced expiration
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Quantitative elemental mapping of granulite-facies monazite: Textural insights and implications for petrochronology
Texturally complex monazite grains contained in two granulite-facies pelitic migmatites from southern Baffin Island, Arctic Canada, were mapped by laser ablation-inductively coupled plasma-mass spectrometry (using spot sizes < 5 µm) to quantitatively determine the spatial variation in trace element chemistry (with up to 1883 analyses per grain). The maps highlight the chemical complexity of monazite grains that have experienced multiple episodes of growth, resorption and chemical modification by dissolution-precipitation during high-grade metamorphism. Following detailed chemical characterisation of monazite compositional zones, a related U-Pb dataset is re-interpreted, allowing petrologically-significant ages to be extracted from a continuum of concordant data. Synthesis of these data with pseudosection modelling of prograde and peak conditions allows for the temporal evolution of monazite trace element chemistry to be placed in the context of the evolving P-T conditions and major phase assemblage. This approach enables a critical evaluation of three commonly used petrochronological indicators: linking Y to garnet abundance, the Eu anomaly to feldspar content, and Th/U to anatectic processes. Europium anomalies and Th/U behave in a relatively systematic fashion, suggesting that they are reliable petrochronological witnesses. However, Y systematics are variable, both within domains interpreted to have grown in a single event, between grains interpreted to be part of the same age population, and between samples that experienced similar metamorphic conditions and mineral assemblages. These observations caution against generalised petrological interpretations on the basis of Y content, as it suggests Y concentrations in monazite are controlled by domainal equilibria. The results reveal a ~45 Myr interval between prograde metamorphism and retrograde melt crystallisation in the study area, emphasising the long-lived nature of heat flow in high-grade metamorphic terranes. Such long timescales of metamorphism would be assisted by the growth, retention and dominance of high-Th suprasolidus monazite, as observed in this study, contributing to the radiogenic heating budget of mid- to lower-crustal environments. Careful characterisation of monazite grains suggests that continuum-style U-Pb datasets can be decoded to provide insights into the duration of metamorphic processes.Natural Sciences and Engineering Research Council Visiting Fellowship
Isaac Newton Trust Research Grant (RG74916
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Consideration of In-Growth of Radionuclides for Facility Hazard Categorization
This paper addresses issues associated with the effects of daughter product in-growth on the hazard categorization of facilities in accordance with DOE-STD-1027-92, “Hazard Categorization and Accident Analysis Techniques for Compliance with DOE Order 5480.23, Nuclear Safety Analysis Reports.” There is a list of issues that occur when performing facility hazard categorizations at DOE facilities. The first issue is when radionuclides are concentrated outside of their natural decay schemes, and the resulting daughter products exceed the hazard category three threshold quantity values (HC3 TQVs) while their parents do not. The second issue is if a parent nuclide is evaluated for the inhalation pathway, and the daughter product is evaluated using a different pathway and methodology. The third issue is when the parent and daughter are evaluated using the same pathway for exposure, but the daughter is significantly more radiotoxic than the parent. Lastly, when the TQVs were derived for hazard categorization, the methodology used involved a 24 hour exposure period during which, for the sake of simplicity, no consideration was given to decay and the subsequent in-growth of daughter products. Facility hazard categorization is a snapshot in time and does not provide an accurate inventory for long term operations and/or storage
Automation in human-machine networks: how increasing machine agency affects human agency
© 2018, Springer International Publishing AG. Efficient human-machine networks require productive interaction between human and machine actors. In this study, we address how a strengthening of machine agency, for example through increasing levels of automation, affect the human actors of the networks. Findings from case studies within air traffic management, emergency management, and crowd evacuation are presented, shedding light on how automation may strengthen the agency of human actors in the network through responsibility sharing and task allocation, and serve as a needed prerequisite of innovation and change
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