928 resultados para Developed
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We use the Aguion and Howitt (2009) theoretical model of endogenous economic growth to explain the declining economic growth in developed economies in the period 1981-2009. Aguion and Howitt theoretical framework combines Solownian and Schumpeterian elements in a single scenario, so that labor-augmenting technological progress and capital accumulation per efficiency unit of labor are both caused not only by exogenous changes in the investment rate but also by shocks to the degree of efficiency in the Research and Development (R&D) expenditure process. Empirical results revealed that per worker output growth rates and capital stock per efficiency unit of labor growth rates both have a common panel unit root. Since the panel cointegration tests and estimates revealed a statistical significant negative long-run relationship between per worker output growth rate and capital stock per efficiency unit of labor, the interpretation of the econometric results analized from the Aguion and Howitt ́s theoretical perspective is that labor-augmenting technological progress is endogenously falling over time mainly because of an exogenous deterioration of the environment conditions for the transformation of the investment rate and R&D expenditures in technological progress.
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Activated carbon was prepared from date pits via chemical activation with H3PO4. The effects of activating agent concentration and activation temperature on the yield and surface area were studied. The optimal activated carbon was prepared at 450 °C using 55 % H3PO4. The prepared activated carbon was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer, Emmett, and Teller (BET) surface area. The prepared date pit-based activated carbon (DAC) was used for the removal of bromate (BrO3 −). The concentration of BrO3 − was determined by ultra-performance liquid chromatography-mass tandem spectrometry (UPLC-MS/MS). The experimental equilibrium data for BrO3 − adsorption onto DAC was well fitted to the Langmuir isotherm model and showed maximum monolayer adsorption capacity of 25.64 mg g−1. The adsorption kinetics of BrO3 − adsorption was very well represented by the pseudo-first-order equation. The analytical application of DAC for the analysis of real water samples was studied with very promising results.
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Simarouba glauca, a non-edible oilseed crop native to South Florida, is gaining popularity as a feedstock for the production of biodiesel. The University of Agriculture Sciences in Bangalore, India has developed a biodiesel production model based on the principles of decentralization, small scales, and multiple fuel sources. Success of such a program depends on conversion efficiencies at multiple stages. The conversion efficiency of the field-level, decentralized production model was compared with the in-laboratory conversion efficiency benchmark. The study indicated that the field-level model conversion efficiency was less than that of the lab-scale set up. The fuel qualities and characteristics of the Simarouba glauca biodiesel were tested and found to be the standards required for fuel designation. However, this research suggests that for Simarouba glauca to be widely accepted as a biodiesel feedstock further investigation is still required.
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The present research aims to analyse the impact of corporate governance and cultural dimensions in dividend policy. The corporate governance and dividend policy have a close relationship, in that both are evidenced in literature to mitigate agency problems. Cultural factors are also related to agency problems. The existence of agency problems and their solutions differs across countries and it is related to the implementation of the mechanisms of governance. So, cultural factors may have influence on corporate governance and dividend policy. Our sample consists in 1 232 companies belonging to the main indices of 38 countries classified as emerging or developed. To measure the quality of firm level corporate governance, we use the ASSET4 Corporate Governance Performance Index, developed by Thomson Reuters, and as proxy of culture we use three cultural dimensions developed by Geert Hofstede, namely uncertainty avoidance, masculinity and indulgence. We obtained significant empirical evidence that firms with high quality of corporate governance pay higher dividends. With regard to cultural factors, we confirm that in countries with high levels of masculinity and uncertainty avoidance, the dividend payout ratio is lower. On the other hand, countries with high level of indulgence have higher dividend payout ratio. However, we verify that the impact of cultural effects is minimized when the firms have a high quality level of corporate governance. Additionally, we found that the impact of corporate governance and cultural factors in dividend policy differs when dealing with emerging or developed countries.
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Background: Intensified selection of polled individuals has recently gained importance in predominantly horned dairy cattle breeds as an alternative to routine dehorning. The status quo of the current polled breeding pool of genetically-closely related artificial insemination sires with lower breeding values for performance traits raises questions regarding the effects of intensified selection based on this founder pool. Methods: We developed a stochastic simulation framework that combines the stochastic simulation software QMSim and a self-designed R program named QUALsim that acts as an external extension. Two traits were simulated in a dairy cattle population for 25 generations: one quantitative (QMSim) and one qualitative trait with Mendelian inheritance (i.e. polledness, QUALsim). The assignment scheme for qualitative trait genotypes initiated realistic initial breeding situations regarding allele frequencies, true breeding values for the quantitative trait and genetic relatedness. Intensified selection for polled cattle was achieved using an approach that weights estimated breeding values in the animal best linear unbiased prediction model for the quantitative trait depending on genotypes or phenotypes for the polled trait with a user-defined weighting factor. Results: Selection response for the polled trait was highest in the selection scheme based on genotypes. Selection based on phenotypes led to significantly lower allele frequencies for polled. The male selection path played a significantly greater role for a fast dissemination of polled alleles compared to female selection strategies. Fixation of the polled allele implies selection based on polled genotypes among males. In comparison to a base breeding scenario that does not take polledness into account, intensive selection for polled substantially reduced genetic gain for this quantitative trait after 25 generations. Reducing selection intensity for polled males while maintaining strong selection intensity among females, simultaneously decreased losses in genetic gain and achieved a final allele frequency of 0.93 for polled. Conclusions: A fast transition to a completely polled population through intensified selection for polled was in contradiction to the preservation of high genetic gain for the quantitative trait. Selection on male polled genotypes with moderate weighting, and selection on female polled phenotypes with high weighting, could be a suitable compromise regarding all important breeding aspects.
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Despite numerous studies reporting on organic consumer profiles, little is known on consumers motivations for buying local and organic products. More precisely, do consumers prefer local products because they want to support local producers or do environment and the question of food miles matter in their choice ? Besides, very little is known about organic consumers in developing countries, since most surveys are generally conducted in developed countries. Our purpose is to fill this double gap. By conducting qualitative surveys based on individual interviews in four developing countries (Brazil, Egypt, Uganda and China) and two European countries, France and Denmark, we plan to study consumers choice for organic products from supermarkets, farmers markets or local organic food network respectively. Products are selected to cover examples of imported organic products that compete with comparable products of local origin. First results from Brazil and France show that French consumers are more concerned by the environment than Brazilian consumers, but that most consumers in both samples are not concerned by food miles and their subsequent environmental impacts. Results also shed light on different patterns related to commitment of supporting small or local farmers, and suggest implications for policy makers.
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2008
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2016
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Diffusion equations that use time fractional derivatives are attractive because they describe a wealth of problems involving non-Markovian Random walks. The time fractional diffusion equation (TFDE) is obtained from the standard diffusion equation by replacing the first-order time derivative with a fractional derivative of order α ∈ (0, 1). Developing numerical methods for solving fractional partial differential equations is a new research field and the theoretical analysis of the numerical methods associated with them is not fully developed. In this paper an explicit conservative difference approximation (ECDA) for TFDE is proposed. We give a detailed analysis for this ECDA and generate discrete models of random walk suitable for simulating random variables whose spatial probability density evolves in time according to this fractional diffusion equation. The stability and convergence of the ECDA for TFDE in a bounded domain are discussed. Finally, some numerical examples are presented to show the application of the present technique.
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Fleck and Johnson (Int. J. Mech. Sci. 29 (1987) 507) and Fleck et al. (Proc. Inst. Mech. Eng. 206 (1992) 119) have developed foil rolling models which allow for large deformations in the roll profile, including the possibility that the rolls flatten completely. However, these models require computationally expensive iterative solution techniques. A new approach to the approximate solution of the Fleck et al. (1992) Influence Function Model has been developed using both analytic and approximation techniques. The numerical difficulties arising from solving an integral equation in the flattened region have been reduced by applying an Inverse Hilbert Transform to get an analytic expression for the pressure. The method described in this paper is applicable to cases where there is or there is not a flat region.
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In this study we examined the impact of weather variability and tides on the transmission of Barmah Forest virus (BFV) disease and developed a weather-based forecasting model for BFV disease in the Gladstone region, Australia. We used seasonal autoregressive integrated moving-average (SARIMA) models to determine the contribution of weather variables to BFV transmission after the time-series data of response and explanatory variables were made stationary through seasonal differencing. We obtained data on the monthly counts of BFV cases, weather variables (e.g., mean minimum and maximum temperature, total rainfall, and mean relative humidity), high and low tides, and the population size in the Gladstone region between January 1992 and December 2001 from the Queensland Department of Health, Australian Bureau of Meteorology, Queensland Department of Transport, and Australian Bureau of Statistics, respectively. The SARIMA model shows that the 5-month moving average of minimum temperature (β = 0.15, p-value < 0.001) was statistically significantly and positively associated with BFV disease, whereas high tide in the current month (β = −1.03, p-value = 0.04) was statistically significantly and inversely associated with it. However, no significant association was found for other variables. These results may be applied to forecast the occurrence of BFV disease and to use public health resources in BFV control and prevention.
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A low temperature synthesis method based on the decomposition of urea at 90°C in water has been developed to synthesise fraipontite. This material is characterised by a basal reflection 001 at 7.44 Å. The trioctahedral nature of the fraipontite is shown by the presence of a 06l band around 1.54 Å, while a minor band around 1.51 Å indicates some cation ordering between Zn and Al resulting in Al-rich areas with a more dioctahedral nature. TEM and IR indicate that no separate kaolinite phase is present. An increase in the Al content however, did result in the formation of some SiO2 in the form of quartz. Minor impurities of carbonate salts were observed during the synthesis caused by to the formation of CO32- during the decomposition of urea.
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The information on climate variations is essential for the research of many subjects, such as the performance of buildings and agricultural production. However, recorded meteorological data are often incomplete. There may be a limited number of locations recorded, while the number of recorded climatic variables and the time intervals can also be inadequate. Therefore, the hourly data of key weather parameters as required by many building simulation programmes are typically not readily available. To overcome this gap in measured information, several empirical methods and weather data generators have been developed. They generally employ statistical analysis techniques to model the variations of individual climatic variables, while the possible interactions between different weather parameters are largely ignored. Based on a statistical analysis of 10 years historical hourly climatic data over all capital cities in Australia, this paper reports on the finding of strong correlations between several specific weather variables. It is found that there are strong linear correlations between the hourly variations of global solar irradiation (GSI) and dry bulb temperature (DBT), and between the hourly variations of DBT and relative humidity (RH). With an increase in GSI, DBT would generally increase, while the RH tends to decrease. However, no such a clear correlation can be found between the DBT and atmospheric pressure (P), and between the DBT and wind speed. These findings will be useful for the research and practice in building performance simulation.
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This research work analyses techniques for implementing a cell-centred finite-volume time-domain (ccFV-TD) computational methodology for the purpose of studying microwave heating. Various state-of-the-art spatial and temporal discretisation methods employed to solve Maxwell's equations on multidimensional structured grid networks are investigated, and the dispersive and dissipative errors inherent in those techniques examined. Both staggered and unstaggered grid approaches are considered. Upwind schemes using a Riemann solver and intensity vector splitting are studied and evaluated. Staggered and unstaggered Leapfrog and Runge-Kutta time integration methods are analysed in terms of phase and amplitude error to identify which method is the most accurate and efficient for simulating microwave heating processes. The implementation and migration of typical electromagnetic boundary conditions. from staggered in space to cell-centred approaches also is deliberated. In particular, an existing perfectly matched layer absorbing boundary methodology is adapted to formulate a new cell-centred boundary implementation for the ccFV-TD solvers. Finally for microwave heating purposes, a comparison of analytical and numerical results for standard case studies in rectangular waveguides allows the accuracy of the developed methods to be assessed.
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For a largely arid country with generally low relief, Australia has a remarkably large number and variety of waterfalls. Found mainly near the coast, close to where most of the population lives and near the major tourist resort areas, these landscape features have long been popular scenic attractions. As sights to see and places to enjoy a variety of recreational activities, waterfalls continue to play an important role in Australia’s tourism, even in seaside resort areas where the main attractions are sunshine, sandy beaches and surf. The aesthetic appeal of waterfalls and their value as recreational resources are recognized by the inclusion of many in national parks. Even here, demands of visitors and pressures from developers raise serious problems. This paper examines the way in which waterfalls have been developed and promoted as tourist attractions, demonstrating their importance to Australian tourism. It considers threats to the sustainable use of waterfall resources posed by power schemes and, particularly, by the tourist industry itself. Queensland’s Gold Coast is selected as a case study, and comparisons are made with other areas in which waterfalls have played important roles as tourist attractions, especially the Yorkshire coast of northeast England. The discussion draws largely on an examination of tourist literature from the nineteenth to the twenty-first century, including holiday brochures and guide books, as well as other published sources, together with field observation in various parts of the world