58 resultados para Direct Strength Method and Experiments

em University of Queensland eSpace - Australia


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In this paper, we assess the relative performance of the direct valuation method and industry multiplier models using 41 435 firm-quarter Value Line observations over an 11 year (1990–2000) period. Results from both pricingerror and return-prediction analyses indicate that direct valuation yields lower percentage pricing errors and greater return prediction ability than the forward price to aggregated forecasted earnings multiplier model. However, a simple hybrid combination of these two methods leads to more accurate intrinsic value estimates, compared to either method used in isolation. It would appear that fundamental analysis could benefit from using one approach as a check on the other.

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The leaching of N fertilisers has led to the formation of nitrate (NO3) accumulations in deep subsoils (>5 m depth) of the Johnstone River catchment. This paper outlines the chemical mechanism by which these NO3 accumulations are formed and maintained. This was achieved via a series of column experiments designed to investigate NO3 leaching in relation to the soil charge chemistry and the competition of anions for exchange sites. The presence of variable charge minerals has led to the formation positive surface charge within these profiles. An increase in the soil solution ionic strength accompanying the fertiliser leaching front acts to increase the positive (and negative) charge density, thus providing adsorption sites for NO3. A decrease in the soil solution ionic strength occurs after the fertiliser pulse moves past a point in the profile, due to dilution with incoming rainwater. Nitrate is then released from the exchange back into the soil solution, thus buffering the decrease in the soil solution ionic strength. Since NO3 was adsorbed throughout the profile in this experiment it does not effectively explain the situation occurring in the field. Previous observations of the sulfate (SO4) profile distribution indicated that large SO4 accumulations in the upper profile may influence the NO3 distribution through competition for adsorption sites. A subsequent experiment investigating the effect of SO4 additions on NO3 leaching showed that NO3 adsorption was minimal in the upper profile. Adsorption of NO3 did occur, though only in the region of the profile where SO4 occupancy was low, i.e. in the lower profile. Therefore, the formation of the NO3 accumulations is dependent on the variable charge mineralogy, the variation of charge density with soil solution ionic strength, and the effects of SO4 competition for adsorption sites.

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The measurement of lifetime prevalence of depression in cross-sectional surveys is biased by recall problems. We estimated it indirectly for two countries using modelling, and quantified the underestimation in the empirical estimate for one. A microsimulation model was used to generate population-based epidemiological measures of depression. We fitted the model to 1-and 12-month prevalence data from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) and the Australian Adult Mental Health and Wellbeing Survey. The lowest proportion of cases ever having an episode in their life is 30% of men and 40% of women, for both countries. This corresponds to a lifetime prevalence of 20 and 30%, respectively, in a cross-sectional setting (aged 15-65). The NEMESIS data were 38% lower than these estimates. We conclude that modelling enabled us to estimate lifetime prevalence of depression indirectly. This method is useful in the absence of direct measurement, but also showed that direct estimates are underestimated by recall bias and by the cross-sectional setting.

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Clifford Geertz was best known for his pioneering excursions into symbolic or interpretive anthropology, especially in relation to Indonesia. Less well recognised are his stimulating explorations of the modern economic history of Indonesia. His thinking on the interplay of economics and culture was most fully and vigorously expounded in Agricultural Involution. That book deployed a succinctly packaged past in order to solve a pressing contemporary puzzle, Java's enduring rural poverty and apparent social immobility. Initially greeted with acclaim, later and ironically the book stimulated the deep and multi-layered research that in fact led to the eventual rejection of Geertz's central contentions. But the veracity or otherwise of Geertz's inventive characterisation of Indonesian economic development now seems irrelevant; what is profoundly important is the extraordinary stimulus he gave to a generation of scholars to explore Indonesia's modern economic history with a depth and intensity previously unimaginable.

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Smoothing the potential energy surface for structure optimization is a general and commonly applied strategy. We propose a combination of soft-core potential energy functions and a variation of the diffusion equation method to smooth potential energy surfaces, which is applicable to complex systems such as protein structures; The performance of the method was demonstrated by comparison with simulated annealing using the refinement of the undecapeptide Cyclosporin A as a test case. Simulations were repeated many times using different initial conditions and structures since the methods are heuristic and results are only meaningful in a statistical sense.

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Objective: To describe the associations between hand osteoarthritis (OA), pain and disability in males and females and to further validate the Australian/Canadian CA hand index (AUSCAN LK3.0). Design: Cross-sectional study of 522 subjects from 101 Tasmanian families (males N=174, females N=348). Hand OA was assessed by two observers using the Altman atlas for joint space narrowing and osteophytes at distal interphalangeal and first carpometacarpal joints as well as a score for Heberden's nodes based on hand photography. Hand pain and function were assessed by the AUSCAN LK3.0 and grip strength by dynamometry in both hands on two occasions. Results: The prevalence of hand CA was high in this sample at 44-71% (depending on site). Pain and dysfunction increased with age while grip strength decreased (all P <0.001). All three measures were markedly worse in women, even after taking the severity of arthritis into account. Hand CA explained 5.7-10% of the variation in function, grip strength and pain scores, even after adjustment for age and sex. Further adjustment suggested that the osteoarthritic associations with function and grip strength were largely mediated by pain. Severity of disease was more strongly associated with these scores than presence or absence. Lastly, the AUSCAN LK3.0 showed a comparable association to grip strength with structural damage providing further evidence of index validity. Conclusions: Hand CA at these two sites makes substantial contributions to hand function, strength and pain. The associations with function and strength measures appear mediated by pain. Gender differences in all three measures persist after adjustment for variation in age and CA severity indicating that factors apart from radiographic disease are responsible. (C) 2001 OsteoArthritis Research Society International.

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In this paper we identify elements in Marx´s economic and political writings that are relevant to contemporary critical discourse analysis (CDA). We argue that Marx can be seen to be e n gaging in a form of discourse analysis. We identify the elements in Marx´s historical materialist method that support such a perspective, and exemplify these in a longitudinal comparison of Marx´s texts.

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A detailed analysis procedure is described for evaluating rates of volumetric change in brain structures based on structural magnetic resonance (MR) images. In this procedure, a series of image processing tools have been employed to address the problems encountered in measuring rates of change based on structural MR images. These tools include an algorithm for intensity non-uniforniity correction, a robust algorithm for three-dimensional image registration with sub-voxel precision and an algorithm for brain tissue segmentation. However, a unique feature in the procedure is the use of a fractional volume model that has been developed to provide a quantitative measure for the partial volume effect. With this model, the fractional constituent tissue volumes are evaluated for voxels at the tissue boundary that manifest partial volume effect, thus allowing tissue boundaries be defined at a sub-voxel level and in an automated fashion. Validation studies are presented on key algorithms including segmentation and registration. An overall assessment of the method is provided through the evaluation of the rates of brain atrophy in a group of normal elderly subjects for which the rate of brain atrophy due to normal aging is predictably small. An application of the method is given in Part 11 where the rates of brain atrophy in various brain regions are studied in relation to normal aging and Alzheimer's disease. (C) 2002 Elsevier Science Inc. All rights reserved.

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The country-product-dummy (CPD) method, originally proposed in Summers (1973), has recently been revisited in its weighted formulation to handle a variety of data related situations (Rao and Timmer, 2000, 2003; Heravi et al., 2001; Rao, 2001; Aten and Menezes, 2002; Heston and Aten, 2002; Deaton et al., 2004). The CPD method is also increasingly being used in the context of hedonic modelling instead of its original purpose of filling holes in Summers (1973). However, the CPD method is seen, among practitioners, as a black box due to its regression formulation. The main objective of the paper is to establish equivalence of purchasing power parities and international prices derived from the application of the weighted-CPD method with those arising out of the Rao-system for multilateral comparisons. A major implication of this result is that the weighted-CPD method would then be a natural method of aggregation at all levels of aggregation within the context of international comparisons.

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BACKGROUND: Intervention time series analysis (ITSA) is an important method for analysing the effect of sudden events on time series data. ITSA methods are quasi-experimental in nature and the validity of modelling with these methods depends upon assumptions about the timing of the intervention and the response of the process to it. METHOD: This paper describes how to apply ITSA to analyse the impact of unplanned events on time series when the timing of the event is not accurately known, and so the problems of ITSA methods are magnified by uncertainty in the point of onset of the unplanned intervention. RESULTS: The methods are illustrated using the example of the Australian Heroin Shortage of 2001, which provided an opportunity to study the health and social consequences of an abrupt change in heroin availability in an environment of widespread harm reduction measures. CONCLUSION: Application of these methods enables valuable insights about the consequences of unplanned and poorly identified interventions while minimising the risk of spurious results.