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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Surgical Freedom in Endoscopic Skull Base Surgery: Quantitative Analysis for Endoscopic Approaches

January 2014 (has links)
abstract: During the past five decades neurosurgery has made great progress, with marked improvements in patient outcomes. These noticeable improvements of morbidity and mortality can be attributed to the advances in innovative technologies used in neurosurgery. Cutting-edge technologies are essential in most neurosurgical procedures, and there is no doubt that neurosurgery has become heavily technology dependent. With the introduction of any new modalities, surgeons must adapt, train, and become thoroughly familiar with the capabilities and the extent of application of these new innovations. Within the past decade, endoscopy has become more widely used in neurosurgery, and this newly adopted technology is being recognized as the new minimally invasive future of neurosurgery. The use of endoscopy has allowed neurosurgeons to overcome common challenges, such as limited illumination and visualization in a very narrow surgical corridor; however, it introduces other challenges, such as instrument "sword fighting" and limited maneuverability (surgical freedom). The newly introduced concept of surgical freedom is very essential in surgical planning and approach selection and can play a role in determining outcome of the procedure, since limited surgical freedom can cause fatigue or limit the extent of lesion resection. In my thesis, we develop a consistent objective methodology to quantify and evaluate surgical freedom, which has been previously evaluated subjectively, and apply this model to the analysis of various endoscopic techniques. This model is crucial for evaluating different endoscopic surgical approaches before they are applied in a clinical setting, for identifying surgical maneuvers that can improve surgical freedom, and for developing endoscopic training simulators that accurately model the surgical freedom of various approaches. Quantifying the extent of endoscopic surgical freedom will also provide developers with valuable data that will help them design improved endoscopes and endoscopic instrumentation. / Dissertation/Thesis / Ph.D. Neuroscience 2014
362

Fysisk aktivitet, rörelserädsla och livskvalitet hos individer som genomgått hjärtinfarkt och/eller hjärtoperation

Palm, Emelie, Josefsson, Sara January 2017 (has links)
Sammanfattning Bakgrund: Hjärt -och kärlsjukdom är den vanligaste folksjukdomen i Sverige. Fler män än kvinnor drabbas och c:a 20% av de som drabbats lider utav rörelserädsla. Fysisk aktivitet är en viktig del i primär- och sekundärprevention. Livskvaliteten kan påverkas negativt efter hjärt-och kärlsjukdom. Syfte: Syftet var att studera samband mellan självskattad fysisk aktivitet, självskattad rörelserädsla och självskattad livskvalitet hos individer som drabbats av hjärtinfarkt och/eller genomgått hjärtoperation. Syftet var även att studera om det fanns några könsskillnader avseende rörelserädsla och livskvalitet i denna patientgrupp. Metod: Studien var en icke-experimentell kvantitativ tvärsnittsstudie där enkäter lagt grunden till beskrivande, korrelerande och jämförande design. Resultat: 29 deltagare medverkade. Totalt 19% av deltagarna led av rörelserädsla. Det förekom ingen skillnad mellan könen i median avseende varken rörelserädsla eller livskvalitet. Korrelationskoefficienten var 0,387 (p = 0,07) mellan fysisk aktivitet och livskvalitet i hela gruppen. Sambandet mellan rörelserädsla och livskvalitet var r = -0,460 (p = 0,03). Konklusion: Resultatet stämmer överens med tidigare forskning avseende andelen individer som lider utav rörelserädsla. Inga skillnader påvisades mellan fysisk aktivitet och livskvalitet men ett måttligt negativt samband förelåg mellan rörelserädsla och livskvalitet.
363

Varför sker förebyggande aktioner mot kärnvapenprogram?

Laurell, Freddy January 2017 (has links)
Some states, like Israel and USA, has carried out preventive attacks on other states’ nuclear programs. The attacked stated have been autocracies rising in power with a violent history and with a different political orientation than those attacking. However, there are states that have fulfilled the same criteria, but that has not been attacked. What motivates a state, due to relative power, to attack another states’ nuclear program? Israel has attacked nuclear plants both in Iraq and Syria, two autocratic states that has been aggressive towards Israel. Iran, which is another state that is acting aggressive towards Israel and has a developing nuclear program, has not been preventively attacked. The purpose of this study is to find out what generally motivates states to attack nuclear programs, and particularly why Israel in particular has not bombed Iran’s nuclear program. A comparative case study with text and data analysis has been used. The comparison is between Iraq in 1981 and Iran 2009-2013 and the analysis consists of questions about Iraq and Iran in relation to Israel about regime type, military capacity, threats and violent conflicts. The result of the analysis shows that Israel has not attacked Iran because there is no history of violent conflicts between the two countries. Israel, on the other hand, has been at war with Iraq several times. Increasing power in a state that possesses nuclear weapons appears more threatening if there is a history of violent conflicts. This is probably the case with Israel and Iran since the definition of power in this study handles only military capability. More investigation on the subject is needed due to this narrow definition of power.
364

Comparação entre forças propulsivas efetivas calculadas e medida durante um palmateio de sustentação / Comparison between calculated and measured effective propulsive forces during a support sculling motion

Gomes, Lara Elena January 2010 (has links)
A força propulsiva gerada durante o palmateio é resultado do somatório das forças de arrasto e de sustentação, sendo que a componente que atua na direção do movimento desejado é igual à força propulsiva efetiva. Essas forças podem ser estimadas a partir de equações hidrodinâmicas, porém essas equações não consideram todos os mecanismos que contribuem para a propulsão. Dessa forma, o objetivo geral do presente estudo foi comparar a força propulsiva efetiva calculada a partir das equações hidrodinâmicas e a força propulsiva efetiva medida durante o palmateio de sustentação (na posição vertical, de cabeça para cima) em cada fase do palmateio. Para isso, uma praticante de nado sincronizado realizou palmateio na posição vertical de cabeça para cima durante 15 segundos, enquanto que dados cinemáticos e cinéticos foram obtidos por viodeogrametria 3D e dinamometria respectivamente. A análise gráfica de Bland e Altman foi usada para comparar as forças propulsivas efetivas medida e calculada durante o palmateio. As forças propulsivas efetivas calculada e medida foram diferentes, sendo a medida maior que a calculada. Ainda, os resultados indicaram que o palmateio executado não foi simétrico, isto é, a orientação e a força propulsiva entre a mão direita e a esquerda foram diferentes. Portanto, o achado do presente trabalho destaca a importância de mecanismos instáveis para a propulsão durante o palmateio, já que as forças estimadas por meio das equações hidrodinâmicas apresentaram resultados inferiores, sendo isso observado ao longo de todo o palmateio. / Propulsive force generated during sculling motion results from drag and lift propulsive forces, and the component acting in the direction of motion is the effective propulsive force. These forces may be calculated using hydrodynamic equations, but these equations do not consider all mechanisms that contribute to the propulsion. Thus, the main purpose of this study was to compare the calculated effective propulsive force using the hydrodynamic equations and the measured effective propulsive force during a support sculling motion (vertical position with the head above the water‟s surface) in each phase of sculling. For this, a practitioner of synchronized swimming performed sculling motion in a vertical position with the head above the water‟s surface during 15 seconds, while kinematic and kinetic data were obtained by 3D videogrammetry and dynamometry respectively. Graphical techniques from Bland and Altman were used to compare the measured effective propulsive force and calculated effective propulsive force during sculling motion. The calculated effective propulsive force and the measured effective propulsive force were different, the measured being greater than the calculated. Moreover, the results indicated sculling motion performed was not symmetric, that is, the orientation and propulsive forces between the right and left hands were different. Therefore, the result of this study highlights the importance of the unsteady mechanisms for the propulsion during sculling motion, because the calculated forces using the hydrodynamic equations presented low values throughout the sculling motion.
365

Comportamento macro e microestrutural de barreiras compactadas para contenção de lixiviados ácidos de resíduos industriais e de mineração

Korf, Eduardo Pavan January 2014 (has links)
A lixiviação de resíduos industriais e de mineração usualmente resultam em águas residuárias com pH extremamente ácido. Estes contaminantes podem migrar para o solo ou percolar através de barreiras de fundo em aterros de resíduos sólidos, perturbando a estrutura do solo e modificando a sua condutividade hidráulica. A adição de cimento Portland a este tipo de barreira pode ser uma opção para a neutralização do pH, buscando reduzir os impactos da lixiviação ácida nas águas subterrâneas. Embora muitos estudos abordem o comportamento de barreiras compactadas quando submetidas à ação dos mais diversos tipos de contaminantes, poucos tem explorado os aspectos microestruturais dos materiais componentes das barreiras e suas modificações ao longo do processo de percolação do contaminante. Neste contexto, este trabalho propôs a avaliação do comportamento microestrutural e macroestrutural de um solo argiloso residual compactado, com e sem a adição de cimento Portland (0, 1 e 2%), para fins de aplicação em barreiras impermeáveis sumetidas à ação de lixiviados ácidos. Os resultados motraram uma notável redução da condutividade hidráulica com a percolação de uma solução a 2% de ácido sulfúrico, a qual foi acompanhada pela ocorrência de recalques e redução do pH. Com relação à análise do tamanho e distribuição dos poros, pôde-se concluir que tanto a adição de cimento como a variação do peso específico de compactação, aliadas à ocorrência de recalques, contribuíram para a redução dos microporos e a consequente redução da condutividade hidráulica. Com relação às modificações químicas e mineralógicas, o ataque ácido promoveu principalmente a solubilização de Fe2O3 nas camadas superiores das amostras ensaiadas, porém não causou alterações significativas na estrutura dos argilominerais. Pode-se inferir que o peso específico de compactação não influenciou os resultados e que a adição de cimento contribuiu de maneira discreta para reduzir o impacto da percolação ácida, na medida em que produziu compostos de Ca e S nas camadas de meio e inferior das amostras, reduziu os microporos e retardou a solubilização de Fe2O3, a qual ocorreu principalmente nas camadas superiores das amostras ensaiadas. / The leaching of industrial and mining solid wastes usually result in wastewaters with extremely acidic pH, which might percolate into the ground or through bottom compacted barriers of landfills, disturbing soil structure and increasing hydraulic conductivity. The addition of Portland cement to containment barriers can be an option for pH neutralization, seeking to reduce the impact of acidic leachate to the groundwater. Although many studies have addressed the behavior of compacted barriers subjected to the action of several types of contaminants, a few have explored the microstructural aspects of barriers component materials and their modifications along the contaminant percolation process. In this context, this work proposed the evaluation of microstructural and macrostructural behavior of a compacted residual clayey soil, with and without the addition of Portland cement (0, 1, and 2%), for purposes of application in containment bottom submitted to acidic leachate percolation. The results showed a noticeable reduction in the compacted soil hydraulic conductivity during the percolation of a 2% sulfuric acid solution, which was accompanied by settlements and pH reduction. Regarding the determination of the size and distribution of pores, it can be concluded that both the addition of cement and the variation of specific weights, coupled with the occurrence of settlements, contributed to the reduction of micropores, which consequently resulted in hydraulic conductivity reduction. Concerning the chemical and mineralogical changes, the acidic attack mainly promoted the solubilization of Fe2O3 in the upper layers of the specimens tested but caused no significant modification in clay minerals structure. It can be inferred that the specific gravity did not influence the results and that the cement addition contributed discretely to reduce the acidic percolation impact, as it produced compounds of Ca and S in the middle and lower layers, reduced micropores, and slowly delayed Fe2O3 solubilization, which occurred mainly in the upper layers of the specimens tested.
366

Ataque acido a argamassa de cimento comum e com escoria : um estudo cinetico e gravimetrico de degradação / Acid attack to mortar prepared with ordinary and slag-modified cements : a gravimetric and kinect degradation study

Bergamaschi, Jonathan Melo 30 July 2007 (has links)
Orientador: Ines Joekes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-08T20:35:59Z (GMT). No. of bitstreams: 1 Bergamaschi_JonathanMelo_M.pdf: 1286873 bytes, checksum: d69d1c5af13c8dd142484b9abdf4423f (MD5) Previous issue date: 2007 / Resumo: Este trabalho descreve o comportamento degradativo de ataque ácido em argamassas preparadas com dois tipos de cimento com escória (compostos) e um sem escória (comum) analisado via gravimetria e pela velocidade de ataque. Os fatores como período de cura, concentração do ácido e tipo (ácido clorídrico, HCl, sulfúrico, H2SO4, e ácido acético, HAc) foram controlados. Nos ensaios de ataque ácido analisados por gravimetria, o ácido sulfúrico se comportou o mais agressivo em todos os tipos de cimento estudados. Porém em ensaios com corpos de prova de CP-III, nas primeiras semanas de imersão neste ácido, houve um aumento de massa. Após esse período a perda de massa foi intensa, devido o agravante do ataque por íons sulfatos. A velocidade de degradação da argamassa é influenciada fortemente pela natureza do ácido. O ácido orgânico é o consumido mais rapidamente. Contudo, para argamassa de cimento composto, a velocidade de consumo de ácido é menor em baixa concentração. HCl ataca mais rapidamente argamassa curada por 28 dias do que H2SO4 em concentração 0,010 mol L. O efeito do tempo de cura mostra diferença de velocidade ao ataque ácido entre HCl e H2SO4; com corpos de prova curados por 7 dias, HCl é mais rapidamente consumido, mas em corpos de prova curados por 91 dias, H2SO4 é consumido mais rápido. A análise de imagens superficiais dos corpos de prova em ensaios utilizando soluções de mesmo pH confirma a proporcionalidade direta entre a força do ácido e a agressividade. Diferente comportamento é também observado para argamassa preparada com diferentes cimentos. Para períodos curtos de cura, cimento composto apresenta baixa velocidade de ataque. No entanto, quando imersos em ácido acético, argamassa de cimento tipo CP-V apresenta baixa velocidade de ataque em períodos longos de cura, quando comparado com cimento com escória. Estes resultados mostram que muitos fatores estudados influenciam na velocidade do ataque ácido e estes restringem as generalizações sobre a resistência dos cimentos. / Abstract: This work describes the degradative behaves of acid attack in mortars prepared with two slag containing cements and one without slag analyzed by gravimetria and kinetic. Conditioning factors as curing period, acid concentration and type (hydrochloric acid, HCl, sulfuric acid, H2SO4, and acetic acid, HAc) were controlled. In experiments of acid attack analyzed by gravimetria, sulfuric acid behaved the most aggressive in all studied types of cement. However in experiments with CP-III specimens, in the first weeks of immersion in sulfuric acid, it had a mass increase. After this period, the loss of mass was intense, due the aggravating of the attack for sulfate. The nature of the acid influences strongly mortar degradation rates. The organic acid is the quickest consumed. However, for slag-mortars, the rate of acid consumption is lower in less concentrated solutions. HCl attacks faster all 28-days cured mortars than H2SO4 in 0.10 mol L solutions. The effect of curing time shows differences among HCl and H2SO4 attack rate; with 7-day cured specimens, HCl is more rapidly consumed, but with 91-day cured specimens, H2SO4 is the fastest consumed. The analysis of superficial images of specimens in experiments using same pH solutions confirms the direct proportionality between the force of acid and its aggressiveness. Different behavior is also observed for mortars prepared with different cements. For short curing times, slag-cement mortars show lower rate of attack. However, when immersed in acetic acid (HAc), type III cement mortars show lower rates of attack at longer curing times, when compared to slag-cement mortars. These results show that every factor studied influenced the rate of acid attack and this restrains cement resistance generalizations. / Mestrado / Físico-Química / Mestre em Química
367

Modelo para análise do ataque no futebol = A model to analyze soccer offensive phase / A model to analyze soccer offensive phase

Ziskind, Fernando Santana 20 August 2018 (has links)
Orientador: Sergio Augusto Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-20T15:41:05Z (GMT). No. of bitstreams: 1 Ziskind_FernandoSantana_M.pdf: 1924673 bytes, checksum: bfe8cad97429390b86db1ee6c588e94d (MD5) Previous issue date: 2012 / Resumo: A análise de jogos de futebol apresenta uma vasta gama de possibilidades que podem estar relacionadas ao desempenho dos atletas e ao resultado do jogo. Em relação a aplicações de análises matemáticas no futebol, a principal forma para analisar a velocidade do ataque na literatura foi apresentada por Yue et al. (2008). O objetivo deste trabalho foi propor um modelo de análise da velocidade de progressão da bola ao gol no futebol e apresentar os resultados de dez jogos da elite do futebol brasileiro. Os jogos foram filmados com quatro a seis câmeras digitais (7,5 a 30 Hz) e as coordenadas bidimensionais dos jogadores durante a partida foram obtidas pelo software Dvideo (Figueroa, Leite e Barros, 2006a; b). As ações técnicas também foram registradas pelo software Dvideo, conforme Moura (2006). Foram levadas em consideração na análise todas as sequências ofensivas do jogo com pelo menos quatro ações técnicas. Em cada sequência ofensiva, para cada par de ações sequenciais (ai e ai+1), os vetores VPG foram calculados obedecendo a seguinte equação: VPG = (vm ? gu)gu onde gu é o vetor unitário de g, definido pelo ponto médio entre as duas ações ai e ai+1 (ponto M) e o ponto médio do gol (G); vm tem direção e sentido definidos pela diferença da posição das ações ai e ai+1, origem no ponto M e módulo igual à velocidade média da bola. Nos casos em que ||VPG|| for diferente de zero, houve progressão ou afastamento da bola em relação ao gol. Sempre que a distância euclidiana entre a ação ai+1 e o gol for menor do que a distância euclidiana entre a ação ai e o gol, isso representará progressão da bola ao gol. Caso contrário, terá ocorrido afastamento. Foram considerados na análise apenas os casos de progressão ao gol. Os resultados para 10 jogos foram apresentados por média e desvio padrão dos valores de ||VPG||. As equipes 5, 13, 17 e 19 obtiveram valores de ||VPG|| significativamente maiores na faixa 1 (próxima ao gol) em comparação com a faixa 2 (longe do gol) da mesma equipe. Equipes que venceram obtiveram valores de ||VPG|| significativamente maiores na faixa 2 do que equipes que perderam. Além disso, os vetores VPG foram apresentados graficamente para 17 gols analisados e para todas as sequências ofensivas terminadas em finalização de cada equipe. Concluiu-se que, além de ter sido possível caracterizar o ataque das equipes com base na velocidade de progressão da bola ao gol, a análise das sequências ofensivas no futebol por meio do modelo proposto apresentou particularidades das sequências ofensivas das equipes que não foram encontrados em outros estudos na literatura e que podem auxiliar na análise de desempenho no futebol / Abstract: Studies related to game analysis in soccer have shown many different variables that might be related to the athlete's performance and match result. Along the mathematical approaches of the soccer game, the main form to analyze the attack speed was presented by Yue et al. (2008). The aim of the present study was to elaborate a model to analyze the ball speed towards the goal in soccer and to show the results from 10 soccer games of Brazilian elite teams. The games were recorded with four to six cameras (7.5 to 30 Hz) and de bidimensional coordinates were obtained using the Dvideo software (Figueroa, Leite e Barros, 2006a; b). Technical actions were also registered using the Dvideo software, as shown in Moura (2006). All offensive sequences with at least four technical actions were considered in the analysis. In each offensive sequence, for every pair of sequential technical actions (ai and ai+1), the vectors VPG were calculated following this equation: VPG = (vm ? gu)gu where gu is the unit vector of g, defined by the middle point between the actions ai and ai+1 (point M) and the middle point of the target goal (G); vm has direction defined by the difference of the position of the actions ai and ai+1, magnitude as the average speed of the ball and origin in the point M. When ||VPG|| ? 0 , it means that there were progression or regression in relation to the goal. When the Euclidian distance between the action ai+1 and the goal is minor than the Euclidian distance between the action ai and the target, goal progression will have happened. Otherwise, the action will have moved the ball away from the goal. Only the cases that progression to the goal occurred were considered in the analysis. The results of ten games were presented by mean and standard deviation of ||VPG||. Teams 5, 13, 17 and 19 showed values of ||VPG|| significantly higher near the goal then far away from the goal, when comparing different sectors of the same team. Teams that won the game showed higher values of ||VPG|| far from the goal than teams that lost the games, when comparing the same sector. Also, VPG vectors were presented graphically for 17 goals and all offensive sequences ended in shots for every team. It was possible to characterize the offensive phase of the teams based on the ball speed towards the goal. In conclusion, the model proposed showed many aspects of the offensive sequences of each team that have not been presented by other studies in the literature and can be useful to analyze match performance in soccer / Mestrado / Biodinamica do Movimento e Esporte / Mestre em Educação Física
368

Cooperative Defense Against DDoS Attack using GOSSIP Protocol

Sohail, Imran, Hayat, Sikandar January 2009 (has links)
The ability to detect and prevent a network from DDoS attack and to ensure the high quality infrastructure is a back bone of today’s network security issues. In this thesis, we have successfully validated an algorithm using OmNet++ Ver. 4.0 simulation to show how a DDoS attack can be detected and how the nodes can be protected from such an attack using GOSSIP protocol.
369

Anomaly based Detection of Attacks on Security Protocols

Kazi, Shehab January 2010 (has links)
Abstract. Security and privacy in digital communications is the need of the hour. SSL/TLS has become widely adopted to provide the same. Multiple application layer protocols can be layered on top of it. However protection is this form results in all the data being encrypted causing problems for an intrusion detection system which relies on a sniffer that analyses packets on a network. We thus hypothesise that a host based intrusion detection system that analyses packets after decryption would be able to detect attacks against security protocols. To this effect we conduct two experiments where we attack a web server and a mail server, collect data, analyse it and conclude with methods to detect such attacks. These methods are in the form of peudocode.
370

Secure hypervisor versus trusted execution environment : Security analysis for mobile fingerprint identification applications

Sundblad, Anton, Brunberg, Gustaf January 2017 (has links)
Fingerprint identification is becoming increasingly popular as a means of authentication for handheld devices of different kinds. In order to secure such an authentication solution it is common to use a TEE implementation. This thesis examines the possibility of replacing a TEE with a hypervisor-based solution instead, with the intention of keeping the same security features that a TEE can offer. To carry out the evaluation a suitable method is constructed. This method makes use of fault trees to be able to find possible vulnerabilities in both systems, and these vulnerabilities are then documented. The vulnerabilities of both systems are also compared to each other to identify differences in how they are handled. It is concluded that if the target platform has the ability to implement a TEE solution, it can also implement the same solution using a hypervisor. However, the authors recommend against porting a working TEE solution, as TEEs often offer finished APIs for common operations that would require re-implementation in the examined hypervisor.

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