3,125 research outputs found
Appraising proposals for water supply investments
The main objective of this paper is to discuss the feasibility
and utility of economic appraisal of community water investments. In the
first section the scope of current investments are detailed. In the second
section we discuss the special problems associated with the proliferation of
self-help water schemes. Public and private water investments together
constitute an important commitment, and we explore the problem of judging
whether this investment is at an appropriate level given national goals
and available resources. It is evident that this difficult question cannot
be satisfactorily answered until we have a more coherent understanding of the
cost-effectiveness of individual schemes.
Finally a set of criteria is suggested which may be used to obtain
information about individual schemes. Application of these appraisal
procedures will sharpen the judgement of decision makers making allocations
within the sector. In aggregate this information will also be valuable to
those concerned with resource allocations to the sector
Narratives Afield: An Oral History Experience
This paper documents the comprehensive process of designing and executing a video oral history project through a case study of The Living History Oral History Project which is accessioned to the Louie B. Nunn Center for Oral History. Discussions of each phase of the project from concept, design, field work, archiving, and interpretation demonstrates how expanding technology increases the narrative opportunities presented by oral history research. The added feature of digital video technology creates visuality, which is an expansion on Alessandro Portelli’s concepts of orality and history telling. Since discoverability and accessibility is a traditional problem in using oral history recordings as research materials, the case study includes discussion of the accessioning process, including indexing using the Oral History Metadata Synchronizer or OHMS. The paper also proposes a format for scholarly citation style to be used with OHMS indexing, based on the Chicago Style Manual. The paper concludes that the combined narrative elements of orality and visuality which rely on recording of sensations, goes beyond memory as the substance of oral history and taps into shared experience as the basis of memory
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Linking metacognition and mindreading: Evidence from autism and dual-task investigations
Questions of how we know our own and other minds, and whether metacognition and mindreading rely on the same processes, are longstanding in psychology and philosophy. In Experiment 1, children/adolescents with autism (who tend to show attenuated mindreading) showed significantly lower accuracy on an explicit metacognition task than neurotypical children/adolescents, but not on an allegedly metacognitive implicit one. In Experiment 2, neurotypical adults completed these tasks in a single-task condition, or a dual-task condition that required concurrent completion of a secondary task that tapped mindreading. Metacognitive accuracy was significantly diminished by the dual-mindreading-task on the explicit task, but not the implicit task. In Experiment 3, we included additional dual-tasks to rule out the possibility that any secondary task (regardless of whether it required mindreading) would diminish metacognitive accuracy. Finally, in both experiments 1 and 2, metacognitive accuracy on the explicit task, but not the implicit task, was associated significantly with performance on a measure of mindreading ability. These results suggest that explicit metacognitive tasks (used frequently to measure metacognition in humans) share metarepresentational processing resources with mindreading, whereas implicit tasks (which are claimed by some comparative psychologists to measure metacognition in non-human animals) do not
Caribou of the Central Arctic Region of Alaska in relation to adjacent caribou herds
There was an unusual increase in numbers of caribou (Rangifer tarandus granti) in the Central Arctic region of Alaska from 1981 to 1985. In fall and winter numbers were up to five times greater than at the onset of calving in June. Numbers appeared to double during the month of June each year, then remain relatively stable over the summer period with a further increase in the fall. Ingress of caribou from outside the region in fall was observed in all years and egress in the early spring is postulated. We conclude that a small resident herd inhabits the region year round with numbers increasing through ingress of caribou from the Western Arctic herd possibly beginning as early as June. Increases or decreases in the size of adjacent herds probably will affect the numbers of caribou occupying the Central Arctic region
High temperature turbine engine structure
A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion
Integral correlation measures for multiparticle physics
We report on a considerable improvement in the technique of measuring
multiparticle correlations via integrals over correlation functions. A
modification of measures used in the characterization of chaotic dynamical
sytems permits fast and flexible calculation of factorial moments and cumulants
as well as their differential versions. Higher order correlation integral
measurements even of large multiplicity events such as encountered in heavy ion
collisons are now feasible. The change from ``ordinary'' to ``factorial''
powers may have important consequences in other fields such as the study of
galaxy correlations and Bose-Einstein interferometry.Comment: 23 pages, 6 tar-compressed uuencoded PostScript figures appended,
preprint TPR-92-4
A Sensitivity Study Relating to Neighbourhood-scale Fast Local Urban Climate Modelling within the Built Environment
The rapid increase in urban populations during the last century, together with the threat of climate change has motivated research focusing on the impact of land-use on urban climates. High-resolution neighbourhood-scale modelling tools developed to account for the complex three-dimensional surfaces and volumes within an urban area are able to predict temperature perturbations over an urban domain with reference to varying land-use. However, land-use classes chosen to model the urban landscape often reflect the function, rather than the material, and hence overlook different building materials that compose the built environment.
The purpose of this study is to demonstrate that in order to robustly assess local climate variations, it is important to use representative land-use parameters that account for materials that form the urban landscape, instead of functions. The response of a high-resolution local climate model to an improved parameterization of the built environment is investigated using the local-scale urban climate modelling tool, ADMS-Urban. In this study, a more elaborate set of land-use classes is collated which distinguishes between different building materials that have varying thermal parameters. A novel approach to calculating the thermal admittance is proposed, reflecting different building materials used for the building facades and the roofs.
This study demonstrates that refining model input parameters to correctly represent various construction materials used within the urban tissue, as well as the proposed, advanced method for calculating thermal admittance leads to significant temperature differences compared to when broad assumptions are used, especially under low wind conditions common in equatorial cities.
Validation studies are planned that will demonstrate the accuracy of model predictions in comparison to observed temperature data in order to identify threshold criteria required to produce realistic urban climate predictions. Following this example of best practice, the existing modelling tools can reliably be used for the simulation of complex future scenarios and for a robust assessment of the relevant health implications
Factorial Moments in a Generalized Lattice Gas Model
We construct a simple multicomponent lattice gas model in one dimension in
which each site can either be empty or occupied by at most one particle of any
one of species. Particles interact with a nearest neighbor interaction
which depends on the species involved. This model is capable of reproducing the
relations between factorial moments observed in high--energy scattering
experiments for moderate values of . The factorial moments of the negative
binomial distribution can be obtained exactly in the limit as becomes
large, and two suitable prescriptions involving randomly drawn nearest neighbor
interactions are given. These results indicate the need for considerable care
in any attempt to extract information regarding possible critical phenomena
from empirical factorial moments.Comment: 15 pages + 1 figure (appended as postscript file), REVTEX 3.0,
NORDITA preprint 93/4
Hydrodynamic scaling from the dynamics of relativistic quantum field theory
Hydrodynamic behavior is a general feature of interacting systems with many
degrees of freedom constrained by conservation laws. To date hydrodynamic
scaling in relativistic quantum systems has been observed in many high energy
settings, from cosmic ray detections to accelerators, with large particle
multiplicity final states. Here we show first evidence for the emergence of
hydrodynamic scaling in the dynamics of a relativistic quantum field theory. We
consider a simple scalar model in 1+1 dimensions in the
Hartree approximation and study the dynamics of two colliding kinks at
relativistic speeds as well as the decay of a localized high energy density
region. The evolution of the energy-momentum tensor determines the dynamical
local equation of state and allows the measurement of the speed of sound.
Hydrodynamic scaling emerges at high local energy densities.Comment: 4 pages, 4 color eps figures, uses RevTex, v2 some typos corrected
and references adde
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