917 resultados para modelos teóricos


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This work aims to present a systematic study of sociology developed by Josué de Castro. It is a theoretical work that aims to evidence the potentialities and limitations of the hunger analysis theoretical models of contemporary sociology. It was used concepts of Social Institution (Berguer and Bourdieu), Habitus-precário and Ralé (Jessé Sousa) as weapons to comprehend better the hunger phenomenon on the sociology field, to consequently generate dialogs between Castros writings and the contemporary sociology. It demonstrates how hunger reproduces more by pre reflexive behavior patterns in a way that the moral rules become invisible and allow the phenomenon to continue in an invisible way

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High levels of local, regional, and global extinctions has progressively simplified communities in terms of both species and ecosystem functioning. Theoretical models demonstrated that the degree of functional redundancy determines the rates of functional group loss in response to species extinctions. Here, we improve the theoretical predictions by incorporating in the model interactions between species and between functional groups. In this study, we tested the effect of different scenarios of interspecific interactions and effects between functional groups on the resistance to loss of community functional groups. Virtual communities have been built with different distribution patterns of species in functional groups, both with high and low evenness. A matrix A was created to represent the net effect of interspecific interactions among all species, representing nesting patterns, modularity, sensitive species, and dominant species. Moreover, a second matrix B was created to represent the interactions between functional groups, also exhibiting different patterns. The extinction probability of each species was calculated based on community species richness and by the intensity of the interspecific interactions that act upon it and group to which it belongs. In the model, successive extinctions decrease the community species richness, the degree of functional redundancy and, consequently, the number of functional groups that remain in the system. For each scenario of functional redundancy, A, and B, we ran 1000 simulations to generate an average functional extinction curve. Different model assumptions were able to generate remarkable variation on functional extinction curves. More extreme variations occurred when the matrix A and B caused a higher heterogeneity in the species extinction probability. Scenarios with sensitive species, positive or negative, showed a greater variation than the scenarios with dominant species. Nested interactions showed greater variation than scenarios where the interactions were in modules. Communities with maximal functional evenness can only be destabilized by the interactions between species and functional groups. In contrast, communities with low functional evenness can have its resistance either increased or decreased by the interactions. The concentration of positive interactions in low redundancy groups or negative interactions in high redundancy groups was able to decrease the functional extinction rates. In contrast, the concentration of negative interactions in low redundancy groups or positive interactions in high redundancy groups was able to increase the functional extinction rates. This model shows results that are relevant for species priorization in ecosystem conservation and restoration

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Water still represents, on its critical properties and phase transitions, a problem of current scientific interest, as a consequence of the countless open questions and of the inadequacy of the existent theoretical models, mainly related to the different solid and liquid phases that this substance possesses. For example, there are 13 known crystalline forms of water, and also amorphous phases. One of them, the amorphous ice of very high density (VHDA), was just recently observed. Other example is the anomalous behavior in the macroscopic density, which presents a maximum at the temperature of 277 K. In order to experimentally investigate the behavior of one of the liquid-solid phase transitions, the anomaly in its density and also the metastability, we used three different cooling techniques and, as comparison systems, we made use of the solvents: acetone and ethyl alcohol. The first studied cooling system employ a Peltier plate, a device recently developed, which makes use of small cubes made up of semiconductors to change heat among two surfaces; the second system is a commercial refrigerator, similar to the residential ones. Finally, the liquid nitrogen technique, which is used to refrigerate the samples in a container, in two ways: a very fast and other one, almost static. In those three systems, three Beckers of aluminum were used (with a volume of 80 ml, each), containing water, alcohol and acetone. They were closed and maintained at atmospheric pressure. Inside of each Becker were installed three thermocouples, disposed along the vertical axis of the Beckers, one close to the inferior surface, other to the medium level and the last one close the superior surface. A system of data acquisition was built via virtual instrumentation using as a central equipment a Data-Acquisition board. The temperature data were collected by the three thermocouples in the three Beckers, simultaneously, in function of freezing time. We will present the behavior of temperature versus freezing time for the three substances. The results show the characterization of the transitions of the liquid

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Episodic memory refers to the recollection of what, where and when a specific event occurred. Hippocampus is a key structure in this type of memory. Computational models suggest that the dentate gyrus (DG) and the CA3 hippocampal subregions are involved in pattern separation and the rapid acquisition of episodic memories, while CA1 is involved in memory consolidation. However there are few studies with animal models that access simultaneously the aspects ‗what-where-when . Recently, an object recognition episodic-like memory task in rodents was proposed. This task consists of two sample trials and a test phase. In sample trial one, the rat is exposed to four copies of an object. In sample trial two, one hour later, the rat is exposed to four copies of a different object. In the test phase, 1 h later, two copies of each of the objects previously used are presented. One copy of the object used in sample trial one is located in a different place, and therefore it is expected to be the most explored object.However, the short retention delay of the task narrows its applications. This study verifies if this task can be evoked after 24h and whether the pharmacological inactivation of the DG/CA3 and CA1 subregions could differentially impair the acquisition of the task described. Validation of the task with a longer interval (24h) was accomplished (animals showed spatiotemporal object discrimination and scopolamine (1 mg/kg, ip) injected pos-training impaired performance). Afterwards, the GABA agonist muscimol, (0,250 μg/μl; volume = 0,5 μl) or saline were injected in the hippocampal subregions fifteen minutes before training. Pre-training inactivation of the DG/CA3 subregions impaired the spatial discrimination of the objects (‗where ), while the temporal discrimination (‗when ) was preserved. Rats treated with muscimol in the CA1 subregion explored all the objects equally well, irrespective of place or presentation time. Our results corroborate the computational models that postulate a role for DG/CA3 in spatial pattern separation, and a role for CA1 in the consolidation process of different mnemonic episodes

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The Layered Double Hydroxides has become extremely promising materials due to its range of applications, easily obtained in the laboratory and reusability after calcination, so the knowledge regarding their properties is of utmost importance. In this study were synthesized layered double hydroxides of two systems, Mg-Al and Zn-Al, and such materials were analyzed with X-ray diffraction and, from these data, we determined the volume density, planar atomic density, size crystallite, lattice parameters, interplanar spacing and interlayer space available. Such materials were also subjected to thermogravimetric analysis reasons for heating 5, 10, 20 and 25 ° C / min to determine kinetic parameters for the formation of metaphases HTD and HTB based on theoretical models Ozawa, Flynn-Wall Starink and Model Free Kinetics. In addition, the layered double hydroxides synthesized in this working ratios were calcined heating 2.5 ° C / min and 20 ° C / min, and tested for adsorption of nitrate anion in aqueous solution batch system at time intervals 5 min, 15 min, 30 min, 1h, 2h and 4h. Such calcined materials were also subjected to exposure to the atmosphere and at intervals of 1 week, 2 weeks and 1 month were analyzed by infrared spectroscopy to study the kinetics of regeneration determining structural called "memory effect"

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Being available as a tourist destination is a necessary condition but not enough for the expansion and success of tourism activity. To be successful, tourism requires investment, inputs, appropriate planning and management, like any other economic activity. A fundamental goal of the destination management is to understand how the competitiveness of a tourist destination can be improved and sustained. Competitive position of tourism can be measured and assessed by various models. Evaluating the indicators of competitiveness of a tourist destination involves a multivariate analysis, ranging from issues directly related to tourism activity itself to the indirect factors. These are elements that are interrelated and that together will point out the competitive condition of this destination. From the definition and characterization of competitiveness, sustainability and management in the context of tourist destinations, understood as the main concepts of this study, we present the main theoretical and methodological models of assessment of competitiveness of tourist destinations in the literature and represent the state of the issue in the scientific treatment of the subject. These models, designed by researchers from several countries and applied in different tourist destinations, are confronted about their structure, indicators considered and localities in which they were applied. The aim of this study was to know and evaluate the condition of tourist competitiveness of the destination Pólo Costa das Dunas, from the constraints attributes of superior performance of the evaluation model of tourist competitiveness of destinations Competenible, suggested by Mazaro, and that suit the requirements of international market aware of the strength and importance of sustainability. The condition of competitiveness of tourist destination in Rio Grande do Norte Pólo Costa das Dunas was moderate. The competitive strengths and weaknesses of the destination Pólo Costa das Dunas revealed through the dozens of sustainable attributes of the model Competenible showed guidelines and initiatives that can be taken to guide strategic decisions related to their planning and management. Thus, this study should serve as support for strategic planning and long-term management of the sector and as a crucial tool for making decisions related to public policies, sectoral investments, monitor processes, strategic planning, direction and control of the local and regional tourism development of destinations

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

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In this work a study of social networks based on analysis of family names is presented. A basic approach to the mathematical formalism of graphs is developed and then main theoretical models for complex networks are presented aiming to support the analysis of surnames networks models. These, in turn, are worked so as to be drawn leading quantities, such as aggregation coefficient, minimum average path length and connectivity distribution. Based on these quantities, it can be stated that surnames networks are an example of complex network, showing important features such as preferential attachment and small-world character

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Pesquisa qualitativa orientada pelos referenciais teórico-metodológicos: Interacionismo Simbólico e Grounded Theory para compreender o processo planejamento-implementação da Sistematização da Assistência de Enfermagem (SAE), segundo dois grupos amostrais: enfermeiros e auxiliares/técnicos de enfermagem de um hospital universitário, e desenvolver uma síntese dos modelos teóricos representativos dessas experiências. A saturação teórica configurou-se mediante a análise da 24ª entrevista não diretiva de 12 enfermeiros e de 12 técnicos de enfermagem, lotados em unidades de internação. da análise emergiram dois modelos teóricos, cuja síntese originou o terceiro, intitulado Entre o êxito e a frustração com a operacionalização da SAE: recursos humanos como componente determinante para a visibilidade do enfermeiro no processo de trabalho. Este modelo desvela o déficit de recursos humanos, impulsionando o enfermeiro a realizar uma SAE ilusória, e perpetuando um processo cíclico de sofrimento, por vivenciar a invisibilidade de sua práxis no processo de trabalho.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fazemos uma releitura dos estudos empíricos sobre empresas multinacionais (EMNs) e comércio exterior no Brasil a partir dos modelos teóricos e empíricos de comércio internacional com firmas multinacionais. Percebe-se que aqueles estudos não examinam como características econômicas do país (Brasil) condicionaram a emergência e tipo das EMNs e, assim, seus respectivos impactos sobre comércio exterior. Conseguem isolar, nas análises de impacto comercial, evidências dos serviços tecnológicos das estrangeiras, relativamente às domésticas do mesmo setor, mas não examinam se essas firmas se concentraram ou não em atividades com vantagens comparativas no país, o que seria crucial para determinar seu impacto comercial comparativo.

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Este artigo trata dos pressupostos teóricos presentes na formação dos educadores ambientais nos cursos de graduação. Esses pressupostos definem um quadro teórico analisado a partir do referencial metodológico do materialismo histórico-dialético. Esse quadro teórico pode ser organizado em concepções naturais, racionais e históricas da relação homem-natureza e da educação e suas análises sugerem princípios metodológicos de organização curricular nesses cursos.

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Pós-graduação em Estudos Linguísticos - IBILCE