874 resultados para GDP Interpolation


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The current thesis manuscript studies the suitability of a recent data assimilation method, the Variational Ensemble Kalman Filter (VEnKF), to real-life fluid dynamic problems in hydrology. VEnKF combines a variational formulation of the data assimilation problem based on minimizing an energy functional with an Ensemble Kalman filter approximation to the Hessian matrix that also serves as an approximation to the inverse of the error covariance matrix. One of the significant features of VEnKF is the very frequent re-sampling of the ensemble: resampling is done at every observation step. This unusual feature is further exacerbated by observation interpolation that is seen beneficial for numerical stability. In this case the ensemble is resampled every time step of the numerical model. VEnKF is implemented in several configurations to data from a real laboratory-scale dam break problem modelled with the shallow water equations. It is also tried in a two-layer Quasi- Geostrophic atmospheric flow problem. In both cases VEnKF proves to be an efficient and accurate data assimilation method that renders the analysis more realistic than the numerical model alone. It also proves to be robust against filter instability by its adaptive nature.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Most of the applications of airborne laser scanner data to forestry require that the point cloud be normalized, i.e., each point represents height from the ground instead of elevation. To normalize the point cloud, a digital terrain model (DTM), which is derived from the ground returns in the point cloud, is employed. Unfortunately, extracting accurate DTMs from airborne laser scanner data is a challenging task, especially in tropical forests where the canopy is normally very thick (partially closed), leading to a situation in which only a limited number of laser pulses reach the ground. Therefore, robust algorithms for extracting accurate DTMs in low-ground-point-densitysituations are needed in order to realize the full potential of airborne laser scanner data to forestry. The objective of this thesis is to develop algorithms for processing airborne laser scanner data in order to: (1) extract DTMs in demanding forest conditions (complex terrain and low number of ground points) for applications in forestry; (2) estimate canopy base height (CBH) for forest fire behavior modeling; and (3) assess the robustness of LiDAR-based high-resolution biomass estimation models against different field plot designs. Here, the aim is to find out if field plot data gathered by professional foresters can be combined with field plot data gathered by professionally trained community foresters and used in LiDAR-based high-resolution biomass estimation modeling without affecting prediction performance. The question of interest in this case is whether or not the local forest communities can achieve the level technical proficiency required for accurate forest monitoring. The algorithms for extracting DTMs from LiDAR point clouds presented in this thesis address the challenges of extracting DTMs in low-ground-point situations and in complex terrain while the algorithm for CBH estimation addresses the challenge of variations in the distribution of points in the LiDAR point cloud caused by things like variations in tree species and season of data acquisition. These algorithms are adaptive (with respect to point cloud characteristics) and exhibit a high degree of tolerance to variations in the density and distribution of points in the LiDAR point cloud. Results of comparison with existing DTM extraction algorithms showed that DTM extraction algorithms proposed in this thesis performed better with respect to accuracy of estimating tree heights from airborne laser scanner data. On the other hand, the proposed DTM extraction algorithms, being mostly based on trend surface interpolation, can not retain small artifacts in the terrain (e.g., bumps, small hills and depressions). Therefore, the DTMs generated by these algorithms are only suitable for forestry applications where the primary objective is to estimate tree heights from normalized airborne laser scanner data. On the other hand, the algorithm for estimating CBH proposed in this thesis is based on the idea of moving voxel in which gaps (openings in the canopy) which act as fuel breaks are located and their height is estimated. Test results showed a slight improvement in CBH estimation accuracy over existing CBH estimation methods which are based on height percentiles in the airborne laser scanner data. However, being based on the idea of moving voxel, this algorithm has one main advantage over existing CBH estimation methods in the context of forest fire modeling: it has great potential in providing information about vertical fuel continuity. This information can be used to create vertical fuel continuity maps which can provide more realistic information on the risk of crown fires compared to CBH.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The paper aims at explaining why Brazil's GDP growth plunged after 1980. Brazil's GDP grew at 7% yearly from 1940 to 1980 but at only 2.5% per year since then. Increases in the relative price of investment that reduced the purchasing power of savings, associated to declines in the productivity of capital, seem to have been the most important factors behind the observed loss of dynamism. The tentative conclusion is that inward-oriented economic policies since the 1970s and, perhaps, even as early as the 1950s, had negative long-run growth implications that were aggravated by populist policies in the early years of the post-1984 redemocratization.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The second phase of Import Substituting Industrialization, commonly known as ISI2, involved the move in Latin America to "heavy" industrialization, from around 1950-80. This period of economic history has been reviled on both the Left and the Right as being one of either heightened dependency or one demonstrating the clear failure of state intervention in the economy. In this research note, a basic statistical analysis is used to back up other descriptive claims that the ISI2 period was rather one of mixed success, with macroeconomic volatility accompanying great progress in GDP and manufacturing growth. In a sense, the ISI2 period succeeded in industrializing the large economies of the period, and contrasts favorably with the record of the succeeding paradigm of neoliberalism. This research note seeks to raise questions about the way we look at the historical period of ISI2, and suggests that a more open-minded perspective could lead to a more effective and sustainable political economy paradigm for the region in the future.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Proteins of the Ras family are central regulators of crucial cellular processes, such as proliferation, differentiation and apoptosis. Their importance is emphasized in cancer, in which the isoforms H-ras, N-ras and K-ras are misregulated by mutations in approximately 20 – 30 % of cases. Thus, they represent major cancer oncogenes and one of the most important targets for cancer drug development. Ras proteins are small GTPases, which cycle between the GTP-bound active and GDP-bound inactive state. Despite the tremendous research conducted in the last three decades, many fundamental properties of Ras proteins remain poorly understood. For instance, although new concepts have recently emerged, the understanding of Ras behavior in its native environment, the membrane, is still largely missing. On the membrane Ras organizes into nanoscale clusters, also called nanoclusters. They differ between isoforms, but also between activation states of Ras. It is considered that nanoclusters represent the basic Ras signaling units. Recently, it was demonstrated that on the membrane Ras adopts distinct conformations, the so-called orientations, which are dependent on the Ras activations state. The membrane-orientation of H-ras is stabilized by the helix α4 and the C-terminal hypervariable region (hvr). The novel switch III region was proposed to be involved in mediating the change between different H-ras orientations. When the regions involved in this mechanism are mutated, H-ras activity is changed by an unknown mechanism. This thesis has explained the connection between the change of Ras orientation on the membrane and Ras activity. We demonstrated that H-ras orientation mutants exhibit altered diffusion properties on the membrane, which reflect the changes in their nanoclustering. The altered nanoclustering consequently rules the activity of the mutants. Moreover, we demonstrated that specific cancer-related mutations, affecting the switch III region of different Ras isoforms, exhibit increased nanoclustering, which consequently leads to stronger Ras signaling and tumorigenicity. Thus, we have discovered nanoclustering increase as a novel mechanism of Ras activity modulation in cancer. The molecular architecture of complexes formed on the membrane upon Ras activation is another poorly understood property of Ras. The following work has provided novel details on the regulation of Ras nanoclustering by a known H-ras-GTP nanoclustering stabilizer galectin-1 (Gal-1). Our study demonstrated that Gal-1 is not able to bind Ras directly, as it was previously proposed. Instead, its effect on H-ras-GTP nanoclustering is indirect, through binding of the effector proteins. Collectively, our findings represent valuable novel insights in the behavior of Ras, which will help the future research to eventually develop new strategies to successfully target Ras in cancer.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

According to recent available information, the Brazilian economy may be entering a cycle of sustained growth. The dominant current interpretation points to the progresses made in terms of monetary stability, Balance of Payments and structural reforms. Indeed, without monetary stability and the commercial opening of the economy, investments would not be increasing and credit growth would not be helping the emergence of millions of new consumers. But these achievements should be taken as generally conditioning, rather than actually shaping the new picture. Some unexpected (not rarely positive) consequences of overcoming the long enduring semi-stagnation, the emergence of China as a major player, and its consequences on the necessary re-structuring of the Brazilian industry, seem to be decisive in the present day redefinition of the Brazilian GDP growth potential.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Are There evidences of deindustrialization in Brazil? This paper aims at analyzing the theoretical concept of deindustrialization, and evaluating if Brazil, following the implementation of economic reforms in the 1990's, has suffered from a " new Dutch disease" . Despite the manufacturing sector declining participation in the Brazilian Gross Domestic Product (GDP), the empirical evidence show that the changes in the economy structure since the mid-1980’s to the end of 2005 should not be described as deindustrialization. Since there was not evidence of either generalized reallocation of resources towards industries based on natural resources, or a pattern of export specialization in goods technologically based on natural resources or even on labor, one cannot conclude that Brazil was infected by a " new Dutch disease" .

Relevância:

10.00% 10.00%

Publicador:

Resumo:

On this paper, we propose a change in the primary surplus' target by the government current account saving. That concept excludes public investment from primary surplus. However, of that change has raised a question about if government current account saving represents a sustainable fiscal policy. Thus, this paper analyses if the change in the primary surplus' target by the government current account saving implies a meaning modification on the debt-to-GDP ratio path. The empirical analysis, which is based on Brazilian monthly data for the period 1999-2005, suggests that the change in fiscal target does not mean a lack of sustain-ability.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This article aims to offer three contributions to the debate on the recent performance of the Brazilian economy. First, it presents approximate quarterly figures for the Brazilian private investment beginning in 1995. Second, it presents estimates of the Brazilian "investment function" which are robust to the presence of structural breaks. Third, it discusses the sensitivity of private investment to increases in the gross aggregate tax rate. Estimates based on national accounting data prior to march 2007 seem to indicate that an increase of 1% of GDP in the tax rate is associated with a reduction of 1% in private investment.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this paper, we develop a theoretical model that considers a non-linear relationship between growth and level of education (human capital). Our econometric estimates demonstrated the causality running from human capital to GDP per capita with U inverted shape. The level of education (human capital) that generates the maximum growth rate lies around 4.5 years. The foremost implication of this result is that States with level of education below this range should have as priority educational policies.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The survival of small companies in the capitalist development. The role of small companies in capitalist development has raised, throughout the years, the analytical curiosity of economists and other social scientists. In spite of the enormous disadvantages that they possess in competing with big capital, there are innumerable reasons for their survival. The empirical evidence is clear in attesting the importance of small companies in terms of GDP share and job creation and, at the same time, their difficulties for surviving. This paper presents a theoretical revision, departing from Marx, Marshall, Steindl and Schumpeter up to some contemporary authors, concerning the role of the small companies in capitalist development, emphasizing the reasons and the difficulties for its survival.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Brazilian economy pulled by the aggregate demand. This article aims to present the demand-led growth theory and some empirical evidences for a demand-led growth regime in Brazil. First of all, we will do a brief review of the theory of demand led-growth, based in the seminal work of Kaldor (1988), for whom long-run growth is determined by the growth rate of consumption expenditures and the growth rate of exports. Based in the empirical methodology developed by Atesoglu (2002), we run some econometric tests for the hypothesis of demand-led growth for Brazilian economy. The results of such tests shown that near of 85% of GDP growth in Brazil in the period 1991-2005 is explained by variables at the demand side of the economy. Besides that, based in the methodology developed by Ledesma and Thirwall (2002), we shown that natural rate of growth for Brazilian economy is endogenous, increasing during boom times. This means that appears to be no restrictions in the supply side of the economy for a faster growth of Brazilian economy. Finally, we argue that a necessary condition for a sustained growth of Brazilian economy is the adoption of a export-led growth model. For such it is necessary to put an end on the actual over-valuation of real exchange rate.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Determinative common factors of currency and financial crisis. This paper identifies and evaluates determinative common factors of currency and financial crisis in relation to 86 crises episodes between 1970-2004, based on factor analysis, cluster and discriminant analysis. One evidenced that the rise of the ratios of domestic credit, fiscal deficit and residents bank deposits to the GDP is inherent to the different types of crises classified for economic literature. It was also identified as common factors to these episodes some indicators that capture the excessive monetary expansion of the economies and that reflect the fall in international reserves, represented by M2/Reserves and Imports/Reserves ratios and also the total volume of international reserves.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The conventional argument favoring capital controls elimination is based on the predictions from the neoclassical model: free international capital mobility would allow capital flows from country where capital is abundant to countries where capital is scarce and the outcome in a global perspective is efficient allocation of savings and income convergence. Within this perspective, financial integration would be particularly beneficial for developing countries resulting in external savings import, temporary increase in per-capita GDP growth rate and a permanent increase in the per-capita GDP level. Using data for a sample of 105 countries from 1980 to 2004 the evidences show that capitals flows from developing to developed countries and that international financial integration and external savings do not increase the conditional convergence rate.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Estimating the return to education the Brazilian legislation of education as an instrument considering. This paper aims to estimate the impact of education on wages in Brazil. GDP, Population, and the number of schools in the state and year when the individual was born as instruments for his education level were used. In this context, the paper consider other instrument, the Brazilian education Law 5692 of 1971. The results show that the Law 5692 of 1971 and the number of schools in the individual's year of birth bears a positive relationship with his education, and the returns to education decrease quite substantially when the method of instrumental variables is used.