680 resultados para isotopos estáveis
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The skin is one of the largest organs of the human body and accounts for about 16% of body weight. The body protection against the external environment microorganisms is one of its most important functions, however is necessary that the skin remain intact for this function be exercised, so that when there is an injury on the skin, the process of restructuring needs to be starts, however this restructuration may also be compromised due to some diseases, justifying even more the need for the development of topical products that promote or accelerate the skin healing. Thus the aim of this study was to extract bullfrog oil and to develop a suitable topical emulsion. Two different oil samples were extracted by hot or organic solvent process. Titration techniques and gas chromatography- mass spectrometry were used to characterize the bullfrog oil. The required hydrophile-lipophile balance (HLBr) of bullfrog oil was determined and a pseudo-ternary phase diagram was constructed. The stability of the topical emulsion was evaluated. Then, cellular viability was determined by MTT assay using normal fibroblasts (3T3) and melanoma (B16F10) cells lines. The hot extraction yield was 60.6%. The major polyunsaturated compounds found were Eicosapentaenoic acid (17.6%) and Arachidonic acid (8.4%). HLBr study demonstrated the presence of stable systems with HLB ranging from 12.1 to 13.5 and the pseudo-ternary phase diagram showed mainly emulsion systems (62%). Topical emulsion showed 390 nm, polydispersity 0.05, zeta potential -25 mV and remained stable for ninety days. The bullfrog oil and topical emulsion did not showed citotoxicity in normal fibroblasts cells. However, these systems showed significantly inhibition of melanoma cells growth. In conclusion, the bullfrog oil presented desirable chemical characteristics required to be used for the development of a pharmaceutical and cosmetic products.
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Magnetic multilayers are the support for the production of spintronic devices, representing great possibilities for miniaturized electronics industry. having the control to produce devices as well as their physical properties from simple multilayer films to highly complex at the atomic scale is a fundamental need for progress in this area, in recent years has highlighted the production of organic and flexible spintronic devices. Because of this trend, the objective of this work was to produce magnetic multilayers deposited on flexible substrate using magnetron sputtering dc technique. Three sets of samples were prepared. The first set composed of the trilayer type CoFe=Cu(t)=CoFe with different thickness of the metallic spacer. The second set consists of two multilayer subgroups, CoFe=Cu in the presence of IrMn layer as a buffer and the next multilayer as cap layer. The third set consisting of non-magnetostrictive multilayer permalloy (Py=Ta and Py=Ag) on flexible substrate and glass. The magnetic properties, were investigated by magnetometry measurements, ferromagnetic resonance and magnetoimpedance (MI), measurements were carried out at room temperature with the magnetic field always applied on the sample plane. For structural analysis, the diffraction X-ray was used. The results of the trilayer showed a high uniaxial anisotropy field for the sample with a spacer of 4.2 nm. For the multilayer in the presence of IrMn layer as the buffer, the study of static and dynamic magnetic properties showed isotropic behavior. For the multilayer in the presence of IrMn layer as a cap, the results of static magnetic properties of the magnetic behavior exhibited a spin valve structure type. However there was a disagreement with results of ferromagnetic resonance measurements, which was justified by the contribution of the unstable and stable grain to the rotatable anisotropy and Exchange bias in ferromagneticantiferromagnetic interface. The third serie of samples showed similar results behavior for the MI Ag multilayers spacer in both substrates. There are also significant MI changes with the Ta spacer, possible associated with the compressive stress on the flexible substrate sample.
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The advance of drilling in deeper wells has required more thermostable materials. The use of synthetic fluids, which usually have a good chemical stability, faces the environmental constraints, besides it usually generate more discharge and require a costly disposal treatment of drilled cuttings, which are often not efficient and require mechanical components that hinder the operation. The adoption of aqueous fluids generally involves the use of chrome lignosulfonate, used as dispersant, which provides stability on rheological properties and fluid loss under high temperatures and pressures (HTHP). However, due to the environmental impact associated with the use of chrome compounds, the drilling industry needs alternatives that maintain the integrity of the property and ensure success of the operation in view of the strong influence of temperature on the viscosity of aqueous fluids and polymers used in these type fluids, often polysaccharides, passives of hydrolysis and biological degradation. Therefore, vinyl polymers were selected for this study because they have predominantly carbon chain and, in particular, polyvinylpyrrolidone (PVP) for resisting higher temperatures and partially hydrolyzed polyacrylamide (PHPA) and clay by increasing the system's viscosity. Moreover, the absence of acetal bonds reduces the sensitivity to attacks by bacteria. In order to develop an aqueous drilling fluid system for HTHP applications using PVP, HPAM and clay, as main constituents, fluid formulations were prepared and determined its rheological properties using rotary viscometer of the Fann, and volume filtrate obtained by filtration HTHP following the standard API 13B-2. The new fluid system using polyvinylpyrrolidone (PVP) with high molar weight had higher viscosities, gels and yield strength, due to the effect of flocculating clay. On the other hand, the low molecular weight PVP contributed to the formation of disperse systems with lower values in the rheological properties and fluid loss. Both systems are characterized by thermal stability gain up to around 120 ° C, keeping stable rheological parameters. The results were further corroborated through linear clay swelling tests.
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The advance of drilling in deeper wells has required more thermostable materials. The use of synthetic fluids, which usually have a good chemical stability, faces the environmental constraints, besides it usually generate more discharge and require a costly disposal treatment of drilled cuttings, which are often not efficient and require mechanical components that hinder the operation. The adoption of aqueous fluids generally involves the use of chrome lignosulfonate, used as dispersant, which provides stability on rheological properties and fluid loss under high temperatures and pressures (HTHP). However, due to the environmental impact associated with the use of chrome compounds, the drilling industry needs alternatives that maintain the integrity of the property and ensure success of the operation in view of the strong influence of temperature on the viscosity of aqueous fluids and polymers used in these type fluids, often polysaccharides, passives of hydrolysis and biological degradation. Therefore, vinyl polymers were selected for this study because they have predominantly carbon chain and, in particular, polyvinylpyrrolidone (PVP) for resisting higher temperatures and partially hydrolyzed polyacrylamide (PHPA) and clay by increasing the system's viscosity. Moreover, the absence of acetal bonds reduces the sensitivity to attacks by bacteria. In order to develop an aqueous drilling fluid system for HTHP applications using PVP, HPAM and clay, as main constituents, fluid formulations were prepared and determined its rheological properties using rotary viscometer of the Fann, and volume filtrate obtained by filtration HTHP following the standard API 13B-2. The new fluid system using polyvinylpyrrolidone (PVP) with high molar weight had higher viscosities, gels and yield strength, due to the effect of flocculating clay. On the other hand, the low molecular weight PVP contributed to the formation of disperse systems with lower values in the rheological properties and fluid loss. Both systems are characterized by thermal stability gain up to around 120 ° C, keeping stable rheological parameters. The results were further corroborated through linear clay swelling tests.
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In this work are considered two bidimensional systems, with distints chacacteristcs and applicabilitys. Is studied the adsorption of transition metals (MT) Fe, Co, Mn and Ru in extended defects, formed by graphene grain boundaries. First in pristine graphene The hollow site of carbon hexagon, in pristine graphene, are the most stable for MT adsorption. The Dirac cone in eletronic structure of graphene was manteined with the presence of MT. For the considered grain boundaries the MT has a greater stability for absorption in the grain boundaries sites in comparison with pristine graphene. Through the energy barrier values, are observed diffusion chanels for MT localized on the grain boundaries. This diffusion chanels indicate a possible formation of nanolines of MT in graphene. For the first stage of the nanolines, ate observed a better stability for the system with greater MT concentration, due to MT-MT interactions. Also, due to the magnetic moment of the MT, the nanolines show a magnetization. For the most stable configurations the system are metallics, particularly for Fe the band structure indicates an anisotropic spin current. In a second study, are considereted the retention capacity for metallic contaminants Cd and Hg in clayminerals, kaolinite (KAO) and montmorillonite (MMT). Through the adsorption energies of contaminantes in the clayminerals, was observed a increase in stability with the increase of contaminants concentration, due to the interaction Cd-Cd and Hg-Hg. Also, was observed that KAO has a strong interaction beteween monolayers than MMT. In this sence, for the adsoption process of contaminantes in the natural form of KAO and MMT, the latter has a better retention capacity, due to the small net work for contaminant intercalation. However, when the modification of clayminerals, with molecules that increase the spacing between monolayers, exist a optimal condition, which the contaminant absorption are more stable in KAO system than in MMT. In the Langmuir adsorption model for the clayminerals in the optimal monolayer spacing, the retention capacity for Cd and Hg in KAO system are 21% greater than in MMT system. Also, for the X-ray Absorption Near Edge Spectroscopy (XANES) for the K edge of Cd and Hg, are found a positive shift of absorption edge with the decreasing of monolayer spacing. This result indicates a possible way to determine the concentration of adsorbed contaminats in relation to unabsorbed ones, from the decomposition of experimental XANES in the obteined spectras.
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This dissertation investigates the effects of internationalization in two gaps related to the capital structure that have not been discussed by the Brazilian literature yet. To this, were developed two independent sections. The first examined what the effects of internationalization on the deviation from the target capital structure. The second examined what the effects of internationalization on speed of adjustment (SOA) of the capital structure. It used data from Brazil, multinational and domestic companies, from 2006 to 2014. The results of the first analysis indicate that internationalization helps reduce the difference between the target and the current debt. That is, to the extent that the level of internationalization increases; whether only export or a combination of export, assets and employees abroad, the gap between the current structure and the target structure decreases. This reduction is given as a function of internationalization as a consequence of the upstream effect of the upstream-downstream hypothesis. Thus, as the Market Timing theory, it can be seen as an opportunity for adjustment of the capital structure, and with the reduction of deviation, there is also a reduction in the cost of capital of the firm. The result of the second analysis indicates that internationalization is able to significantly increase the speed adjustment, ensuring for the multinational a faster adjustment of its capital structure. Exports increase the SOA in 9 to 23%. And when also kept active assets and employees abroad the increase is 8 to 20%. In terms of time, while domestic company takes more than three years to reduce half of the deviation that has, while multinacional companies take on average one and a half year to reduce the same proportion of the deviation. The validity of the upstream-downstream hypothesis for the effect of internationalization in SOA was confirmed by comparing the results for US companies. Thus, the phenomenon of internationalization increases SOA when companies are from less stable markets, such as Brazil; and it has a less significcative effect when companies are derived from more stable markets, because they already have a high speed of adjustmennt. In addition, the adequacy analysis of the estimators also showed the model pooled OLS (Ordinary Least Squares) presents the highest quality in predicting the SOA than the system GMM (Generalized Method of Moments). For future studies it is suggested to analyze the effect of international event, by itself, and to validate the hypothesis using samples of different markets and the use of other estimators.
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Ao longo dos anos, a análise de risco de crédito tem vindo a assumir um papel decisivo na análise do financiamento das empresas, sendo este um elemento fundamental para os órgãos de gestão. O financiamento é um elemento muito importante de suporte à atividade empresarial, uma vez que as empresas não detendo capital para realizar o investimento ou atividades correntes, recorrem ao crédito. Para que as empresas possam diminuir o risco de perdas, elas têm de seguir políticas de análise de crédito e de cobranças muito rigorosas. Este controlo será mais eficaz e eficiente se a organização mantiver relações de proximidade com os seus clientes. Um dos métodos cada vez mais utilizados para se conseguir manter relações estáveis e duradouras passa por adotar estratégias de CRM – Customer Relationship Management. A presente dissertação tem como objetivo desenvolver um modelo de análise de risco de crédito para os clientes da empresa inCentea. Este modelo permitirá perceber se o cliente reúne as condições necessárias para atribuição de crédito, e assim diminuir os risco para a inCentea. Conclui-se que a utilização de um maior número de variáveis na avaliação do risco permite uma minimização do risco. Através da integração do modelo de análise de crédito no software de CRM, a inCentea poderá fundamentar a sua decisão de concessão ou não de crédito com base em indicadores económicos e financeiros.
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No setor alimentar, o controlo da qualidade dos produtos e dos processos é uma etapa essencial, uma vez que é por este meio que se avaliam os padrões exigidos, quer a nível de legislação, quer a nível de mercado. O presente trabalho teve, como objetivos principais, o desenvolvimento de um novo produto alimentar com adição de algas, bem como o controlo de qualidade a nível de uma unidade fabril de produção de sumos e polpas naturais, à base de hortofrutícolas. De forma a garantir a qualidade na obtenção de produtos, foi realizado, diariamente, o controlo de entradas dos produtos hortofrutícolas, o acompanhamento de processos nas linhas de produção da fábrica e a análise das amostras de referência. Considerando a tendência e potencial de crescimento apresentados pelo setor das bebidas, nomeadamente dos sumos de fruta naturais, juntamente com a incessante procura por ingredientes naturais ricos em vários nutrientes e com propriedades bioativas, tem-se vindo a registar o lançamento de um número considerável de bebidas inovadoras, onde as macroalgas têm merecido um papel de destaque. Desta forma, procedeu-se à elaboração de dois protótipos, nomeadamente, sumo de framboesa e sumo de espinafres, com a adição do extrato da alga Gelidium corneum, estabilizados através do processo de Hiperpressão a frio, com o intuito de se avaliar o impacto desse extrato nos diferentes parâmetros de qualidade dos sumos. No que respeita aos parâmetros físico-químicos, o pH e teor de sólidos solúveis (TSS) foram avaliados após produção (t0), no tempo intermédio (t15) e no tempo final (t30). A cor foi determinada no t0 e no t30 e os restantes parâmetros, como acidez titulável, quantificação total de polifenóis, capacidade de redução do radical DPPH, teor de proteína bruta, teor de cinzas, teor de minerais e oligoelementos e teor de vitaminas (A, B1, B2 e C) foram avaliados no tempo final (t30). Foram, também, avaliados os parâmetros microbiológicos mais significativos, nomeadamente, microrganismos totais a 30 ˚C, Escherichia coli, Salmonella spp, bolores e leveduras (ao t0, t15 e t30) e realizou-se uma avaliação sensorial ao 29.º dia após produção. Estes sumos apresentaram-se microbiologicamente estáveis, não se tendo verificado crescimento microbiológico durante o período de armazenamento de 30 dias. A análise dos resultados físico-químicos permitiram constatar que a adição do extrato da alga Gelidium corneum aos sumos influenciou as suas características, tendo havido um aumento significativo do pH com a consequente diminuição da acidez titulável e um aumento do teor de sólidos solúveis, em comparação com os sumos controlo. Em relação à avaliação da cor, no caso das amostras de sumos de framboesa, verificou-se que a adição do extrato de algas influenciou o parâmetro a*. No entanto, ambas as amostras permitiram a manutenção deste parâmetro, ao longo do tempo. Quanto ao parâmetro b*, as duas amostras de sumo com algas demonstraram uma evolução mais estável, em relação aos respetivos controlos. No que respeita ao teor em minerais, a adição do extrato da alga demonstrou aumentar os teores de magnésio, sódio, potássio e iodo. Em termos sensoriais, o sumo de framboesa com algas obteve maior aceitação por parte do painel de provadores, podendo-se constatar que o atributo da cor foi o que mostrou maiores variações, entre as duas amostras.
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This text is a first that the author would develop later. It is illustrated with case studies and original terminology. It begins with a brief conceptual contribution on the difference in approach between the German and French geographical schools, and continues with a reflection on the historical and geographical relativity of the boundary. Subsequently, at its greatest extent, the article provides a taxonomy of states: amorphous states, in three cases, that of the "savage peoples" without boundaries, of black Africa; that of semi-civilized peoples of northwest Africa, and the particular case of European civilized nomads, called ―terranovas‖. Framed states, with borders undergoing processes of emergence or extension, especially the case of Yugoslavia. And, in addition, some references to stable boundaries of Albania and the Netherlands
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O presente trabalho tem como objetivo definir, analisar e identificar por meio de um estudo de caso, as dimensões de comprometimento organizacional: afetivas, instrumental e normativa dos gestores do campus do Limoeiro do Norte, que estão em fase de estágio probatório e dos gestores do campus Fortaleza que já passaram desse estágio, traçar um comparativo e relacionar ambos os casos. Norteado por um modelo teórico de comprometimento organizacional abordado por Meyer e Allen (1991; 1997). Comprometimento no setor público neste estudo tem-se como unidade de análise duas instituições federais de educação, ciência e tecnologia. Como os gestores são, na maioria das vezes, responsáveis pelo desenvolvimento de uma força de trabalho capaz e comprometida, sua atuação torna-se de fundamental importância no âmbito da educação, aliado a competência técnica e a vontade política de ações planejadas. De acordo com a pesquisa descritiva e quantitativa, foram aplicados questionários já testados e validados, contendo aspectos semi-estruturados, onde foi dividido em duas partes: a primeira, com seis itens, abordando as características pessoais e funcionais dos gestores do IFCE de cada campus estudado, e segunda, que possui dezoito itens divididos nas três dimensões do comprometimento organizacional: afetivo, instrumental e normativo, tudo baseado na escala de mensuração do comprometimento de Meyer e Allen (1997) modelo internacionalmente aceito e validado. Os resultados obtidos na pesquisa apontaram que dos 35 gestores do campus Limoeiro do Norte o comprometimento organizacional que obteve maior média foi o afetivo. Os gestores estáveis do campus Fortaleza, também apontaram a dimensão afetiva com a maior média de comprometimento. Com isso os estudos balizam que não há uma possível relação com o fator tempo na instituição, uma vez que a maioria dos gestores do campus Fortaleza possui mais de uma década de atuação, enquanto os do campus Limoeiro do Norte, possuem menos de três anos na instituição. A maior parte dos pesquisados nos campi defendem uma forte relação na instituição, já se sentem de casa, o vínculo se estabelece pela presença de sentimentos, afeição e identificação, até mesmo pelo fato dos gestores permanecerem mais tempo no trabalho que na sua prápria casa, ele faz da organização um esteio do seu próprio lar. Conclui-se que os resultados não permitem afirmar que as dimensões do comprometimento estão relacionadas ao tempo de atuação dos gestores na instituição. / This paper aims to define, analyze and identify through a case study, the dimensions of organizational commitment: affective, continuance and normative managers campus of Castle Hayne, who are in their probationary period and the managers of Fortaleza campus who have passed this stage, draw a comparison and to relate both cases. Guided by a theoretical model of organizational commitment by Meyer and Allen (1991; 1997) approached. Commitment in the public sector in this study has as unit of analysis two federal institutions of science and technology education. As managers are, in most cases, responsible for developing a workforce capable and committed, its performance becomes very important in education, combined with technical competence and political will of planned actions. According to the descriptive and quantitative research, questionnaires were applied, tested and validated, containing aspects of semi-structured, which was divided into two parts: the first, with six items, addressing the personal and functional characteristics of the managers of each campus IFCE studied, and second, which has eighteen items divided into the three dimensions of organizational commitment: affective, continuance and normative, all based on a scale to measure the commitment of Meyer and Allen (1997) model is internationally accepted and validated. The results obtained in this research showed that the 35 managers of the Castle Hayne campus organizational commitment that was obtained more affective. Managers stable campus Fortaleza, also pointed to the affective dimension with the highest average commitment. With this guiding studies that there is a possible relationship with the time factor in the institution, since most managers campus Fortaleza has over a decade of operation, while the Castle Hayne campus, have less than three years in institution. Most of the campuses surveyed favor a strong relationship with the institution, already feel at home, the link is established by the presence of feelings, affection and identification, even by the fact that managers stay longer at work than at home, he is a mainstay of the organization of your own home. We conclude that the results do not allow us to state that the dimensions of commitment are related to time of performance of managers in the institution.
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As transformações nas relações contratuais e na ligação psicológica do indivíduo à organização motivaram a realização do presente estudo. Os seus objectivos centrais consistiram em, por um lado, analisar a influência do tipo de vínculo na formação do Contrato Psicológico dos indivíduos com a organização e, por outro lado, compreender a relação do Contrato Psicológico com o Empenhamento na Carreira e com o Commitment Organizacional, e o que poderá distinguir estas relações. A metodologia apoiou-se num questionário, aplicado a uma amostra de 102 profissionais com vínculos de trabalho estáveis e instáveis, de diferentes organizações, ramos profissionais e sectores de actividade. A amostra é proporcional e representativa. (a) Os resultados demonstram que os profissionais prestadores de serviço são o único caso em que o tipo de vínculo tem influência significativa sobre a formação do Contrato Psicológico, percepcionando uma ligação transaccional com a organização. (b) Em contrapartida, provam que uma maior ou menor estabilidade contratual não tem influência significativa sobre os Contratos Psicológicos relacional ou equilibrado. (c) Os resultados sugerem ainda que o Contrato Psicológico está mais directamente relacionado com o Empenhamento na Carreira do que com o Commitment Organizacional. O Contrato Psicológico apresenta correlações fortes com o Empenhamento na Carreira e a consequente utilização de comportamentos individuais de Gestão de Carreira, sendo esta mais significativa nas ligações psicológicas de tipo equilibrado e relacional. No que respeita ao Commitment Organizacional, este não apresenta relação significativa com o Contrato Psicológico mas verificamos a existência de focus de Commitment Organizacional. Os resultados comprovam que o Contrato Psicológico se correlaciona com a sua dimensão normativa. As conclusões evidenciam o incremento das relações transaccionais, motivadas pela menor durabilidade dos vínculos e o desenvolvimento de reduzidas expectativas na relação com a organização e para o carácter individual e circunstancial das ligações psicológicas, que já não obedecem a um padrão tipo. Perante cenários de grande instabilidade, independentemente do Contrato Psicológico estabelecido, a preocupação com a Carreira ganha relevância. Os profissionais actuais tendem a transferir a preocupação com o vínculo e a segurança no emprego para questões de carreira, segurança de empregabilidade e sucesso psicológico. Observa-se que a lealdade à organização é na maior parte dos casos transferida para a lealdade à carreira. / Transformations in contractual relationships and in the psychological connection of an individual to an organization have motivated the execution of the present study. The main objectives of this study were, on the one hand, to analyze the influence of the type of contractual bond in the shaping of the psychological contract of individuals with an organization, and, on the other hand, to understand the relationship between the psychological contract, the career commitment and the organizational commitment, to understand subsequently what may distinguish these relationships. The methodology was supported by a questionnaire, which was applied to a sample of 105 professionals with both stable and unstable contractual bonds in different organizations, professional lines of business and activity sectors. The sample is proportional and representative. (a) The results demonstrate that service providing professionals are the only case in which the type of contractual bond has a significant influence on the shaping of a psychological contract, perceived as a transactional connection with the organization. (b) On the other hand a higher or lower contractual stability has no significant influence or relationship with the psychological contract, relational or balanced. (c) The results also suggest that the psychological contract is more directly related to career commitment than to organizational commitment. The psychological contract shows a strong correlation with the career commitment and the consequent use of the individual behaviour of Career Management, with the latter being more significant to a balanced and relational type of psychological connection. In regard to Organizational Commitment, this presents no significant relationship with the psychological contract but the focus on the organizational commitment is verified. The results also show that the psychological contract is correlated with its normative dimension. The increase in transactional relationships are evident. This is driven by reduction of the durability of contractual bonds and the development of reduced expectations in relation to the organization and the individual character and circumstance of the psychological connections, which no longer conform to a standard type. Scenarios of great instability, regardless of the psychological contract established, cause the concern with career to gain relevance. Current professionals tend to transfer their concerns about contractual bonds and job security to career issues, job security and psychological success. It can also be seen that loyalty to the organization is, in most cases, transferred to loyalty to the career.
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Recent paradigms in wireless communication architectures describe environments where nodes present a highly dynamic behavior (e.g., User Centric Networks). In such environments, routing is still performed based on the regular packet-switched behavior of store-and-forward. Albeit sufficient to compute at least an adequate path between a source and a destination, such routing behavior cannot adequately sustain the highly nomadic lifestyle that Internet users are today experiencing. This thesis aims to analyse the impact of the nodes’ mobility on routing scenarios. It also aims at the development of forwarding concepts that help in message forwarding across graphs where nodes exhibit human mobility patterns, as is the case of most of the user-centric wireless networks today. The first part of the work involved the analysis of the mobility impact on routing, and we found that node mobility significance can affect routing performance, and it depends on the link length, distance, and mobility patterns of nodes. The study of current mobility parameters showed that they capture mobility partially. The routing protocol robustness to node mobility depends on the routing metric sensitivity to node mobility. As such, mobility-aware routing metrics were devised to increase routing robustness to node mobility. Two categories of routing metrics proposed are the time-based and spatial correlation-based. For the validation of the metrics, several mobility models were used, which include the ones that mimic human mobility patterns. The metrics were implemented using the Network Simulator tool using two widely used multi-hop routing protocols of Optimized Link State Routing (OLSR) and Ad hoc On Demand Distance Vector (AODV). Using the proposed metrics, we reduced the path re-computation frequency compared to the benchmark metric. This means that more stable nodes were used to route data. The time-based routing metrics generally performed well across the different node mobility scenarios used. We also noted a variation on the performance of the metrics, including the benchmark metric, under different mobility models, due to the differences in the node mobility governing rules of the models.
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Esta dissertação é composta por 5 artigos.
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Com o presente trabalho pretende-se discutir a importância do DNA na resolução de casos de investigação forense. O Homem, desde os tempos mais remotos tem revelado interesse na confirmação da identidade dos seus semelhantes, pelo desenvolvimento e prática de diversas técnicas de identificação. A partir de uma revisão da literatura, fez-se o estudo dos métodos de identificação humana, sendo este mais aprofundado no que diz respeito ao DNA. Frequentemente são encontrados corpos em que a única peça disponível para o processo de identificação é o dente. As peças dentárias são as estruturas mais resistentes e estáveis do corpo humano, mantendo as suas características e propriedades por longos períodos de tempo pós-morte. A análise do DNA contribui de forma muito importante para os processos de reconhecimento humano, principalmente em casos em que outros métodos de identificação falham devido a decomposição, fragmentação, incineração ou inexistência de dados comparativos ante-morte. Para a obtenção de um perfil genético é necessário executar as seguintes etapas: extração do DNA, sua quantificação e amplificação seguida de análise de determinadas regiões do genoma. Nos dias de hoje, muitos casos de identificação necessitam de uma abordagem multidisciplinar, isto porque em algumas situações existe falta de material padrão ou, por outro lado, pode haver mais do que uma evidência a ser examinada.
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As estruturas de solo reforçado com geossintéticos são normalmente constituídas por solos granulares com boas propriedades físicas e mecânicas. O uso de apenas este tipo de solos pode proporcionar o aumento, por vezes insustentável, do custo da execução das estruturas e o aumento do seu impacto ambiental. Deste modo, as estruturas de solo reforçado perdem a sua vantagem competitiva em relação a outros tipos de estruturas (muros de betão, muros de gravidade, muros de gabiões, etc.). Para resolver este problema podem ser utilizados outros tipos de solos (solos locais, finos, com propriedades físicas e mecânicas piores mas, no entanto, mais baratos) para a execução deste tipo de estruturas. De forma geral, com este estudo pretendeu-se contribuir para o incremento do conhecimento sobre a utilização de solos finos para a construção de estruturas de solo reforçado (muros e taludes). Para tal avaliaram-se as diferenças no comportamento mecânico dos materiais compósitos (solo granular reforçado versus solo fino reforçado) e das estruturas de solo reforçado constituídas com os dois tipos de solos. Assim, os objetivos deste estudo foram avaliar: a influência de vários parâmetros nas propriedades mecânicas e na capacidade de carga dos solos reforçados com geossintéticos; a influência de vários parâmetros no dimensionamento das estruturas de solo reforçado; e o comportamento das estruturas dimensionadas (incluindo a estabilidade global e a influência do processo construtivo) recorrendo a uma ferramenta numérica (PLAXIS). Para cumprir os objetivos propostos foram realizadas análises experimentais em laboratório (análise do comportamento do solo reforçado através de ensaios triaxiais e de California Bearing Ratio) e análises numéricas (dimensionamento de estruturas de solo reforçado; modelação numérica do comportamento através de uma ferramenta numérica comercial com o método dos elementos finitos). Os resultados dos ensaios experimentais mostraram que o comportamento mecânico e a capacidade de carga do solo foram incrementados com a inclusão das camadas de geossintético. Este efeito variou com os diversos parâmetros analisados mas, de forma geral, foi mais importante no solo fino (solo com propriedades mecânicas piores). As análises numéricas mostraram que as estruturas de solo fino precisaram de maior densidade de reforços para serem estáveis. Além disso, as estruturas de solo fino foram mais deformáveis e o efeito do seu processo construtivo foi mais importante (principalmente para estruturas de solo fino saturado).