801 research outputs found
Distributed lag models for hydrological data
The distributed lag model (DLM), used most prominently in air pollution studies, finds application
wherever the effect of a covariate is delayed and distributed through time. We explore the use of modified formulations
of DLMs to provide flexible varying-coeficient models with smoothness constraints, applicable in any setting in which
lagged covariates are regressed on a time-dependent response. The models are applied to simulated flow and rainfall
data and to flow data from a Scottish mountain river, with particular emphasis on approximating the relationship
between environmental covariates and flow regimes in order to detect the influence of unobserved processes. It was
found that under certain rainfall conditions some of the variability in the influence of rainfall on flow arises through
a complex interaction between antecedent ground wetness and the time-delay in rainfall. The models are able to
identify subtle changes in rainfall response, particularly in the location of peak influence in the lag structure and offer
a computationally attractive approach for fitting DLMs
Confidence intervals for a spatially generalized, continuous simulation flood frequency model for Great Britain
There is growing interest in the application of "continuous simulation'' conceptual rainfall-runoff models for flood frequency estimation as an adjunct to event-based or statistical design methodology. The approach has advantages that stem from the use of models with continuous water balance accounting. Conceptual rainfall-runoff models usually require calibration, which in turn requires gauged rainfall and flow data. One of the key challenges is therefore to develop ways of generalizing models for use at ungauged sites. Recent work has produced a prototype scheme for achieving this aim in Great Britain for two catchment models by relating model parameters to spatial catchment properties, such as soils, topography, and geology. In this paper we present an analysis of the uncertainty associated with one of the generalized models ( the "probability distributed model'') in terms of confidence intervals for simulations at test sites that are treated as if they were ungauged. This is done by fitting regression relationships between hydrological model parameters and catchment properties so as to estimate the parameters as distribution functions for the ungauged site case. Flood flow outputs are then simulated from the parameter distributions and used to construct approximate confidence intervals. Comparison with gauged data suggests that the generalized model may be tentatively accepted. Uncertainty in the modeled flood flows is often of a similar order to the uncertainty surrounding a more conventional statistical model, in this case a single-site generalized Pareto distribution fitted to the gauged data
Analysis and use of VAS satellite data
A series of interrelated investigations has examined the analysis and use of VAS (VISSR Atmospheric Sounder) satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. However, the meteorological significance of small or short lived stability features was uncertain. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. The radiance data often did not have a decisive influence on the final satellite soundings. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small scale retrieval features, especially in the dew points, were often of uncertain origin
Analysis and use of VAS satellite data
Four interrelated investigations have examined the analysis and use of VAS satellite data. A case study of VAS-derived mesoscale stability parameters suggested that they would have been a useful supplement to conventional data in the forecasting of thunderstorms on the day of interest. A second investigation examined the roles of first guess and VAS radiometric data in producing sounding retrievals. Broad-scale patterns of the first guess, radiances, and retrievals frequently were similar, whereas small-scale retrieval features, especially in the dew points, were often of uncertain origin. Two research tasks considered 6.7 micron middle tropospheric water vapor imagery. The first utilized radiosonde data to examine causes for two areas of warm brightness temperature. Subsidence associated with a translating jet streak was important. The second task involving water vapor imagery investigated simulated imagery created from LAMPS output and a radiative transfer algorithm. Simulated image patterns were found to compare favorably with those actually observed by VAS. Furthermore, the mass/momentum fields from LAMPS were powerful tools for understanding causes for the image configurations
Confocal Microscopy of Plant Cells
The increasing availability of confocal microscopy has begun a revolution in plant biology in which microscopy has again become a powerful tool for understanding structure and function. Examples of applications include: three dimensional (3D) reconstruction of the interphase microtubule array in large vacuolated epidermal cells (1); measuring cytoplasmic free calcium changes in whole maize coleoptile segments in response to phototropic and gravitropic stimuli (2); and studying symplastic phloem connections in intact Arabidopsis roots (3). The major reason for this revolution is the ability to collect clear images in three dimensions due to the lack of image degradation caused by out-of-focus light. Plant cells can attain very large sizes (hundreds of micrometers, in some cases) and are very thick. Thus the ability of the confocal microscope to obtain optical sections of tissues from which 3D reconstructions can be made surpasses the limitations of conventional “wide-field” microscopic techniques where microtome sectioning is often required and cells must be viewed as flat, two-dimensional objects. Furthermore, the reduction in out-of-focus flare increases depth discriminatio
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Hyperresolution information and hyperresolution ignorance in modelling the hydrology of the land surface
There is a strong drive towards hyperresolution earth system models in order to resolve finer scales of motion in the atmosphere. The problem of obtaining more realistic representation of terrestrial fluxes of heat and water, however, is not just a problem of moving to hyperresolution grid scales. It is much more a question of a lack of knowledge about the parameterisation of processes at whatever grid scale is being used for a wider modelling problem. Hyperresolution grid scales cannot alone solve the problem of this hyperresolution ignorance. This paper discusses these issues in more detail with specific reference to land surface parameterisations and flood inundation models. The importance of making local hyperresolution model predictions available for evaluation by local stakeholders is stressed. It is expected that this will be a major driving force for improving model performance in the future.
Keith BEVEN, Hannah CLOKE, Florian PAPPENBERGER, Rob LAMB, Neil HUNTE
NASA Astronaut Selection 2009: Behavioral Overview
NASA's multi-phase U.S. astronaut selection process seeks to identify the most qualified astronaut candidates from a large number of applicants. With the approaching retirement of the Space Shuttle, NASA focused on selecting those individuals who were most suited to the unique demands of long-duration spaceflight. In total, NASA received 3,535 applications for the 2009 astronaut selection cycle. Of these, 123 were invited to NASA Johnson Space Center (JSC) for Round 1 initial screening and interviews, which consisted of an Astronaut Selection Board (ASB) preliminary interview, medical review, and psychological testing. Of these, 48 individuals were invited to return for Round 2. This round consisted of medical testing, further behavioral assessments, and a second ASB interview. Following this, nine astronaut candidates (ASCANs) were ultimately chosen to go forward to basic training. The contents, benefits, and lessons learned from implementing this phased process will be discussed. The lessons learned can benefit the future selection of space flyers, whether they are NASA or commercial. Learning Objective: 1) Familiarization with the 2009 NASA behavioral screening process for astronaut applicants
Technical Note: The CREDIBLE Uncertainty Estimation (CURE) toolbox: facilitating the communication of epistemic uncertainty
There is a general trend for increasing inclusion of uncertainty estimation in the environmental modelling domain. We present the CREDIBLE Uncertainty Estimation (CURE) Toolbox, an open source MATLABTM toolbox for uncertainty estimation aimed at scientists and practitioners that are not necessarily experts in uncertainty estimation. The toolbox focusses on environmental simulation models and hence employs a range of different Monte Carlo methods for forward and conditioned uncertainty estimation. The methods included span both formal statistical and informal approaches, which are demonstrated using a range of modelling applications set up as workflow scripts. The workflow scripts provide examples of how to utilise toolbox functions for a variety of modelling applications and hence aid the user in defining their own workflow: additional help is provided by extensively commented code. The toolbox implementation aims to increase the uptake of uncertainty estimation methods within a framework designed to be open and explicit, in a way that tries to represent best practice in applying the methods included. Best practice in the evaluation of modelling assumptions and choices, specifically including epistemic uncertainties, is also included by the incorporation of a condition tree that allows users to record assumptions and choices made as an audit trail log.</p
Turismo acessível para todos, um paradigma emergente e um desafio para a oferta turística. O caso dos espaços museológicos e empreendimentos turísticos de Cascais.
Reflexão sobre o turismo acessível para todos, como modelo que se revela cada vez mais essencial para todo o sistema turístico, que se afirma não só pela sua relevância social, cívica e demográfica mas também pelas potencialidades económicas associadas. Todavia, o turismo acessível constitui um desafio de adaptação para a oferta turística instalada há vários anos, em destinos turísticos mais antigos, como é o caso de Cascais.Reflection on accessible tourism for all, as an increasingly essential model for the touristic system, that claims not only for its social, civic and demographic significance, but also for the economic potential associated. However, the accessible tourism is an adaptation challenge for the elderly tourism supply, at long-established tourism destinations, such as Cascais
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