59 resultados para Dynamics evolution
Resumo:
Learning novel actions and skills is a prevalent ability across multiple species and a critical feature for survival and competence in a constantly changing world. Novel actions are generated and learned through a process of trial and error, where an animal explores the environment around itself, generates multiple patterns of behavior and selects the ones that increase the likelihood of positive outcomes. Proper adaptation and execution of the selected behavior requires the coordination of several biomechanical features by the animal. Cortico-basal ganglia circuits and loops are critically involved in the acquisition, learning and consolidation of motor skills.(...)
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We investigate the role of permanent and transitory shocks for firms and aggregate dynamics. We find that permanent shocks to productivity and permanent shifts in the composition of output explain at least four-fifths of firms’ dynamics. However, these permanent shocks are almost uncorrelated across firms and are therefore less relevant for aggregate dynamics. Transitory shocks, on the other hand, are not very important at the firm level,but they account for most of the volatility of aggregate hours and output, because they are significantly correlated across firms. Finally, we try to make some progress on the interpretation of the shocks.
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This work models the competitive behaviour of individuals who maximize their own utility managing their network of connections with other individuals. Utility is taken as a synonym of reputation in this model. Each agent has to decide between two variables: the quality of connections and the number of connections. Hence, the reputation of an individual is a function of the number and the quality of connections within the network. On the other hand, individuals incur in a cost when they improve their network of contacts. The initial value of the quality and number of connections of each individual is distributed according to an initial (given) distribution. The competition occurs over continuous time and among a continuum of agents. A mean field game approach is adopted to solve the model, leading to an optimal trajectory for the number and quality of connections for each individual.
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Theropods form a highly successful and morphologically diversified group of dinosaurs that gave rise to birds. They include most, if not all, carnivorous dinosaurs, yet many theropod clades were secondarily adapted to piscivory, omnivory and herbivory, and theropods show a large array of skull and dentition morphologies. This work aims to investigate aspects of the evolution of theropod dinosaurs by analyzing in detail both the anatomy and ontogeny of teeth and quadrates in non-avian theropods, and by studying embryonic and adult material of a new species of theropod. A standardized list of terms and notations for each anatomical entity of the tooth, quadrate, and maxilla is here proposed with the goal of facilitating descriptions of these important cranial and dental elements. The distribution of thirty dental characters among 113 theropod taxa is investigated, and a list of diagnostic dental characters is proposed. As an example, four isolated theropod teeth from the Lourinhã Formation (Kimmeridgian‒Tithonian) of Portugal are described and identified based on a cladistic analysis performed on a data matrix of 141 dentition-based characters coded in 60 taxa. Two shed teeth are referred to an abelisaurid, providing the first record of Abelisauridae in the Jurassic of Laurasia and the one of the oldest records of this clade in the world, suggesting a possible radiation of Abelisauridae in Europe well before the Upper Cretaceous. The consensus tree resulting from this phylogenetic analysis, the most extensive on theropod teeth, indicates that theropod teeth provide reliable data for identification at approximately family level, and this method will help identifying theropod teeth with more confidence. A detailed description of the dentition of Megalosauridae is also provided, and a discriminant analysis performed on a dataset of numerical data collected on the teeth of 62 theropod taxa reveals that megalosaurid teeth are hardly distinguishable from other theropod clades with ziphodont dentition. This study highlights the importance of detailing anatomical descriptions and providing additional morphometric data on teeth with the purpose of helping to identify isolated theropod teeth. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, a phylogenetic morphometric analysis as well as a cladistic analysis using 98 discrete quadrate related characters were conducted. The quadrate morphology by its own provides a wealth of data with strong phylogenetic signal, and the phylogenetic morphometric analysis reveals two main morphotypes of the mandibular articulation of the quadrate linked to function. As an example, six isolated quadrates from the Kem Kem beds (Cenomanian) of Morocco are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, morphometric, and phylogenetic morphometric analyses. Morphofunctional analysis of the spinosaurid mandibular articulation has shown that the posterior parts of the two mandibular rami displaced laterally when the jaw was depressed due to a mediolaterally oriented intercondylar sulcus of the quadrate. Such lateral movement of the mandibular ramus was possible due to a movable mandibular symphysis in spinosaurids, allowing the pharynx to be widened. A new species of theropod from the Lourinhã Formation of Portugal, Torvosaurus gurneyi, is erected based on a right maxilla and an incomplete caudal centrum. This taxon supports the mechanism of vicariance that occurred in the Iberian Meseta during the Late Jurassic when the proto-Atlantic was already well formed. A theropod clutch containing several crushed eggs and embryonic material is also assigned to this new species of Torvosaurus. Investigation on the maxilla ontogeny in basal tetanurans reveals that crown denticles, elongation of the anterior ramus, and fusion of interdental plates appear at a posthatchling stage. On the other hand, maxillary pneumaticity is already present at an embryonic stage in non-avian theropods.
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The main purpose of this report is to inform about the work developed throughout the curricular training period, which took place in the Legal Department of The Portuguese Football Federation. Firstly, and in general terms, issues such as the evolution of football in Portugal and Sports Federations will be dealt with in this study. In addition, a characterization of the welcoming entity will be done as well, focusing not only on its legal context, but also on its organic structure and operating dynamics. Also, the work developed during the training period will be made known, namely the activities undertaken as part of the project. Besides all the above-mentioned, a study has been carried out essentially on the Regional District Football Associations, in what concerns the statutes of the various associations ( object of study ), including the statutes of FPF- since the main goal of this work is to understand whether the various District and Regional Football Associations, as regular partners of the Portuguese Football Federation, do or do not comply with the Duty of Statutory Adjustment imposed by it, regarding the amendment to the Sports Federation legal regime.
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Waves of globalization reflect the historical technical progress and modern economic growth. The dynamics of this process are here approached using the multidimensional scaling (MDS) methodology to analyze the evolution of GDP per capita, international trade openness, life expectancy, and education tertiary enrollment in 14 countries. MDS provides the appropriate theoretical concepts and the exact mathematical tools to describe the joint evolution of these indicators of economic growth, globalization, welfare and human development of the world economy from 1977 up to 2012. The polarization dance of countries enlightens the convergence paths, potential warfare and present-day rivalries in the global geopolitical scene.
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Scarcity of fuels, changes in environmental policy and in society increased the interest in generating electric energy from renewable energy sources (RES) for a sustainable energy supply in the future. The main problem of RES as solar and wind energy, which represent a main pillar of this transition, is that they cannot supply constant power output. This results inter alia in an increased demand of backup technologies as batteries to assure electricity system safety. The diffusion of energy storage technologies is highly dependent on the energy system and transport transition pathways which might lead to a replacement or reconfiguration of embedded socio-technical practices and regimes (by creating new standards or dominant designs, changing regulations, infrastructure and user patterns). The success of this technology is dependent on hardly predictable future technical advances, actor preferences, development of competing technologies and designs, diverging interests of actors, future cost efficiencies, environmental performance, the evolution of market demand and design and evolution of our society.
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Large chromosomal rearrangements are common in natural populations and thought to be involved in speciation events. In this project, we used experimental evolution to determine how the speed of evolution and the type of accumulated mutations depend on the ancestral chromosomal structure and genotype. We utilized two Wild Type strains and a set of genetically engineered Schizosaccharomyces pombe strains, different solely in the presence of a certain type of chromosomal variant (inversions or translocations), along with respective controls. Previous research has shown that these chromosomal variants have different fitness levels in several environments, probably due to changes in the gene expression along the genome. These strains were propagated in the laboratory at very low population sizes, in which we expect natural selection to be less efficient at purging deleterious mutations. We then measured these strains’ changes in fitness throughout this accumulation of deleterious mutations, comparing the evolutionary trajectories in the different rearrangements to understand if the chromosomal structure affected the speed of evolution. We also tested these mutations for possible epistatic effects and estimated their parameters: the number of arising deleterious mutations per generation (Ud) and each one’s mean effect (sd).
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Given the importance of fiscal balance for ensuring a sustainable fiscal policy, we conduct an empirical examination of fiscal dynamics in the United States in response to unsustainable budget deviations. We concentrate on the role of political factors, namely the Republican - Democrat presidential divide, in determining the fiscal response to budget disequilibria. Making use of an asymmetric cointegration framework, we explore politically motivated fiscal asymmetries in the US, from Eisenhower to Obama. We conclude that political factors such as the government’s political quadrant and the timing of elections are important determinants of the fiscal response to unsustainable budget deviations.
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Abstract: The Stability Growth Pact and the 3% rule did not prevent countries from running large deficits. Countries in the EMU administrate fiscal policies differently, despite the existence of a common quantitative goal. The main focus of this work project is to study differences in the fiscal dynamics of eight EMU countries and assess the role of political variables in shaping those dynamics. We find that elections negatively affect government revenue in Austria, Belgium, Portugal, Spain and Germany. Expenditure, on the other hand, responds positively to incoming elections in Portugal, Italy, France and Netherlands, and negatively in the case of Germany.
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This work was developed in the context of the MIT Portugal Program, area of Bioengineering Systems, in collaboration with the Champalimaud Research Programme, Champalimaud Center for the Unknown, Lisbon, Portugal. The project entitled Dynamics of serotonergic neurons revealed by fiber photometry was carried out at Instituto Gulbenkian de Ciência, Oeiras, Portugal and at the Champalimaud Research Programme, Champalimaud Center for the Unknown, Lisbon, Portugal
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The evolution of a technology and the understanding of the moment in its life cycle is of the utmost importance to the entry strategy devised by any company. Having the entry of EDP Brazil on the micro-generation market as background, the present workproject attempts to summarize the most important topics in management literature concerning the theory of technology life-cycles and the updated literature on developments of photovoltaic technology to infer the current positioning of this technology in the theoretical models. The need for this type of work stems from the very common lack of bridging between the academic research of economic aspects relevant to the evolution of technologies and the agents of research on specific technological issues. When this occurs, namely due to the external nature of research to companies, thereby escaping the harsh economic controls of a profit seeking enterprise, the evolution many times lacks the appropriate framework to be studied on a more forward looking manner and to allow for management decisions to be based on.
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The Gallus gallus (chicken) embryo is a central model organism in evolutionary developmental biology. Its anatomy and developmental genetics have been extensively studied and many relevant evolutionary implications have been made so far. However, important questions regarding the developmental origin of the chicken skull bones are still unresolved such that no solid homology can be established across organisms. This precludes evolutionary comparisons between this and other avian model systems in which skull anatomy has evolved significantly over the last millions of years.(...)