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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.
21

A Structurally Based Investigation of Abdominal Aortic Aneurysms in Mouse Models

Collins, Melissa 2011 December 1900 (has links)
Understanding the mechanical properties of Abdominal Aortic Aneurysms is paramount to improving treatment of this deadly condition. Here, we present work that makes strides in understanding not only the mechanical behavior and constitutive parameters of the two vessels that experience AAAs in different models, but also the effects of three major components of AAA formation. Biaxial mechanical tests were performed using a modified computer- controlled device. We examined the solid mechanics of the infrarenal and suprarenal aorta to examine why non-targeted models of AAAs (like Ang-II infusion) form exclusively in the suprarenal aorta whereas in humans the lesions preferentially form in the infrarenal aorta. The major difference between the two vessels is the elastin content and lamellar thickness in the suprarenal aorta. We analyzed the mechanical and constitutive effects of an acute loss of functional elastin via intraluminal exposure to elastase. We found that after elastase exposure, vessels were less distensible and experienced non-uniform, but modest dilatation. The constitutive parameters reflect elastin loss and increased collagen loading. We detailed the loss of smooth muscle cell contractility as found in human lesions that form in the thoracic aorta. We examined wild-type (WT), heterozygous (HET), and null (KO) a-smooth muscle actin (a-SMA) mice. The data and associated constitutive parameters were nearly identical amongst the three groups. We studied the biaxial mechanical tests on Angiotensin-II-infused ApoE-/- mice. This model is common model of AAA; however, instead of dilation and a thinning of the wall as in AAAs, Ang-II results in a dissecting aneurysm with adventitial growth. The pressure-diameter curves show a lack of sigmoidal shape attributed to elastin, there is some distensibility. The pressure-force behavior of these vessels is similar to a native vessel, unlike the pressure-force behavior of the elastase vessels. We have added a piece to the puzzle in understanding why AAAs occur preferentially in the suprarenal in mice as opposed to the infrarenal in humans. Our work with the a-SMA mice, introduces the idea that missense mutations in the ACTA2 gene, rather than the knocking out of the gene, leads to vascular diseases. We have increased the knowledge of the Ang-II infusion model by presenting biaxial mechanical data of the resulting dilatations. We have also further explored this widely used AAA model via histology to determine that in it is not a model for aneurysm development, but is a dissecting adventitial disease.
22

A case study of handling load spikes in authentication systems

Sverrisson, Kristjon January 2008 (has links)
<p>The user growth in Internet services for the past years has caused a need to re-think methods for user authentication, authorization and accounting for network providers. To deal with this growing demand for Internet services, the underlying user authentication systems have to be able to, among other things, handle load spikes. This can be achieved by using loadbalancing, and there are both adaptive and non-adaptive methods of loadbalancing.</p><p>This case study compares adaptive and non-adaptive loadbalancing for user authentication in terms of average throughput. To do this we set up a lab where we test two different load-balancing methods; a non-adaptive and a adaptive.</p><p>The non-adaptive load balancing method is simple, only using a pool of servers to direct the load to in a round-robin way, whereas the adaptive load balancing method tries to direct the load using a calculation of the previous requests.</p>
23

Avaliação dos efeitos de dietas enriquecidas com frutos das espécies Theobroma grandiflorum e Musa spp AAA em diferentes modelos de inflamação intestinal

Chagas, Alexandre da Silveira. January 2017 (has links)
Orientador: Luiz Claudio Di Stasi / Resumo: A Doença Inflamatória Intestinal (DII) é uma doença com etiologia desconhecida e sem terapêutica curativa disponível, englobando, fundamentalmente, duas doenças distintas: a Doença de Crohn (DC) e a Retocolite Ulcerativa (RCU), ambas caracterizadas por uma inflamação crônica do intestino, com períodos de exacerbação seguidos de intervalos prolongados com remissão dos sintomas, cujo tratamento com os fármacos disponíveis apresentam sérios efeitos colaterais. Portanto, o desenvolvimento de novas estratégias de tratamento que combinem eficácia e segurança é uma importante meta na terapia da DII. Produtos de origem natural, especialmente oriundos de fontes vegetais com propriedades de modificar a microbiota intestinal têm sido amplamente estudados como agentes preventivos e/ou curativo destas doenças, visto que a manipulação da microbiota intestinal tem se mostrado como uma estratégia importante na manutenção da homeostase colônica. Neste contexto, muitos frutos de origem tropical, com ampla utilização pela população e ricos em fibras e/ou componentes que ativos como antioxidantes e/ou anti-inflamatórios podem representar uma nova estratégia complementar para a prevenção ou cura da DII. Dentre eles se destacam os frutos das espécies Theobroma grandiflorum (cupuaçu) e Musa spp AAA (banana nanica), ricos em fibras alimentares e compostos fenólicos, os quais são potencialmente benéficos no tratamento e prevenção da DII. O objetivo do presente trabalho foi avaliar os efeitos de uma d... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor
24

Zabezpečený přístup k lokální počítačové síti / Secure access to local area network

Kočiš, Jan January 2016 (has links)
This master's thesis deals with the field of secure access to the local area computer network. The main aim of the thesis is to characterize theoretical background of controlled access to computer networks, which includes security principles, recommended practices, authentication methods, network protocols and related processes. This thesis also includes practical usage of acquired knowledge by implementing secure access to local area network in a real environment. The first part characterize the theoretical principles underlying the design and implementation of the entire system. The practical part deals with the implementation of specific secure access to the local area computer network solution in the engineering company. The first part introduces the company, its environment and requirements. The following section describes performed analysis of the original state and based on the obtained information summarizes the proposed solution. Implementation of the comprehensive system of the controlled access to the local area network is described in detail in the next section. Description of the system deployment into production operation process, the definition of acceptance tests and recommendations for solving of potential issues are part of this work as well. Conclusion chapter contains summary of the system's economic aspects and the potential impacts on information systems operation in the company. Final evaluation summarizes the thesis, highlights the benefits of the implemented system and analyses its weak points, with recommendations for further development. It finds the designed secure access to the local network as a suitable, secure and practical way to control access to local network resources.
25

Autentizace síťových portů pomocí protokolu 802.1X ve firemním prostředí

Malinka, Tomáš January 2014 (has links)
This thesis describes the draft and implementation of a new security with 802.1x in the corporate environment. The work is divided into two parts. The first part outlines the topic theoretically and the second part solves specific draft using 802.1x and its implementation in the corporate environment. The implementation is outlined with configuration of end clients, switches including RADIUS server and settings in AD. During the implementation, there is also described the authentication of devices by Mac Authentication Bypass.
26

Caracterização do gene ftsH de Streptomyces sp Y7 / Caracterization of ftsH gene of Streptomyces sp Y7

Paixão, Cinthia Ferreira da 14 December 2002 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-11-10T17:07:26Z No. of bitstreams: 2 Dissertação - Cintia Ferreira da Paixão - 2002.pdf: 501587 bytes, checksum: f00ca727b973e5102f7af9c24d03a9ee (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2014-11-10T17:07:39Z (GMT) No. of bitstreams: 2 Dissertação - Cintia Ferreira da Paixão - 2002.pdf: 501587 bytes, checksum: f00ca727b973e5102f7af9c24d03a9ee (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-10T17:07:39Z (GMT). No. of bitstreams: 2 Dissertação - Cintia Ferreira da Paixão - 2002.pdf: 501587 bytes, checksum: f00ca727b973e5102f7af9c24d03a9ee (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2002-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The actinomycets are Gram-positive bacterias, aerobic with rich DNA in G+C (larger than 60%) and immobile. They are found practically in all the environment, forming ramified filaments or hyphae that persist in the mycelium form. The Streptomyces constitutes 90% of the isolated actinomycets of the soils, in spite of they are also found in aquatic atmospheres and interior of some plants. They stand out for the diversity of production of hidrolytics enzymes and antibiotics, 70% of the know antibiotics are produced by those microorganisms. Aiming to clone genes with biotechnological interest, a genomic libraries of the Streptomyces sp Y7 isolated of the soil of Cerrado was constructed. After the analyses of the sequences of the genomics libraries of Streptomyces sp Y7, it was selected a plasmid named pFS8, that displayed similarity with ftsH genes. The ftsH gene encodes a metalloprotease ATPase and Zn+2 dependent, belongs to the AAA family (ATPases associated with a variety of cellular activities). It is involved with several cellular functions such as secretory proteins export and degradation of transcriptional factors (sigma 32 and Lambda CII). The data of sequencing showed that the ftsH gene was incomplete. In order to characterize if the product of this gene showed biological activity, it was made tests to evaluate the functionality of the fusions proteins in an ftsH-negative E.coli strain AR3291. AR3291 cells transformed with this plasmid showed a general growth advantage upon the cells AR3291. The protein produced did not present toxicant effects for cells AR3289, which had normal ftsH gene. The truncated protein obtained was also analyzed to prediction of the structure “coiled-coil”, that is common to the other FtsH studied, and the results showed those truncated proteins did nor form “coiled-coil” structure. We also tested whether fusion proteins decreased or inhibited the defective transfer of citosolic proteins. / Os actinomicetos são bactérias Gram-positivas, aeróbicas e com DNA rico em G+C (mais que 60%). São encontrados em quase todos ambientes, formando hifas ramificadas que persistem na forma de micélio. Os Streptomyces constituem cerca de 90% dos actinomicetos isolados de solos, apesar de serem encontrados em ambientes aquáticos e no interior de algumas plantas. Os Streptomyces são grandes produtores de enzimas hidrolíticas e antibióticos, 70 % dos antibióticos conhecidos são produzidos por esses microrganismos. Com o objetivo de clonar genes de interesse biotecnológico, foi construída uma biblioteca genômica de Streptomyces sp Y7 isolado de solo de Cerrado. A partir das análises das seqüências das bibliotecas genômicas foi selecionado o plasmídeo pFS8 que apresentava homologia com o gene ftsH. O gene ftsH codifica uma metaloprotease ATP Zn2+ dependente, pertencente a família AAA (ATPases Associadas a diversas Atividades celulares). Os dados do seqüenciamento mostraram que o gene ftsH clonado estava incompleto. A fim de caracterizar o produto do gene ftsH, foram feitos testes para avaliar a funcionalidade dessas proteínas de fusão em células mutadas para o gene ftsH (AR3291). A proteína de fusão produzida por pFS9 é capaz de recuperar o crescimento das células AR3291 e a proteína produzida por pFS8 não apresenta efeitos tóxicos para células AR3289, que não têm mutação para o gene ftsH. Também foi analisado se as proteínas produzidas por pFS8 e pFS9 formam a estrutura “coiled coil” que é comum aos outros organismos estudados. Outra característica analisada nesse trabalho foi a capacidade da proteína produzida por pFS9 diminuir ou inibir a translocação anormal de proteínas para o meio externo. Os resultados mostram que essa proteína não inibe a translocação de proteínas para o meio externo, enquanto que a proteína produzida por pFS8 apresenta efeito contrário a proteína produzida por pFS9.
27

A case study of handling load spikes in authentication systems

Sverrisson, Kristjon January 2008 (has links)
The user growth in Internet services for the past years has caused a need to re-think methods for user authentication, authorization and accounting for network providers. To deal with this growing demand for Internet services, the underlying user authentication systems have to be able to, among other things, handle load spikes. This can be achieved by using loadbalancing, and there are both adaptive and non-adaptive methods of loadbalancing. This case study compares adaptive and non-adaptive loadbalancing for user authentication in terms of average throughput. To do this we set up a lab where we test two different load-balancing methods; a non-adaptive and a adaptive. The non-adaptive load balancing method is simple, only using a pool of servers to direct the load to in a round-robin way, whereas the adaptive load balancing method tries to direct the load using a calculation of the previous requests.
28

AAA-protokoll : En jämförelse mellan protokollen RADIUS och Diameter

Svensson, Tommy January 2010 (has links)
AAA-protokoll är ett protokoll som hanterar uppkopplingsförfrågningar och bokför använda resurser hos användare för att senare kunna ta betalt. Det kan användas för mer än detta så som att erbjuda uppkoppling till trådlösa nätverk. AAA-protokoll erbjuder en centraliserad punkt för administration av uppkopplingshantering och nätverksåtkomst.RADIUS-protokollet är det mest använda AAA-protokollet i världen på grund av sin flexibilitet och öppna standarder. Protokollet innehåller dock en del brister mot funktionalitet och säkerhet, så som att protokollet är svagt mot man-i-mitten-attacker. Diameter är uppföljaren till RADIUS och är det bättre av dem båda. Arbetet går igenom, med fokus på säkerhet och funktionalitet, ifall Diameter rättar till de brister som finns i RADIUS och samtidigt om Diameter är ett protokoll för framtiden.Resultatet som presenteras är att Diameter förbättrar nästan alla de brister som uppdagats mot säkerhet och funktionalitet i RADIUS. De mest kritiska bristerna med RADIUS är dess skalbarhet och dess brist på trafikstockningskontroll i större organisationers nätverk. RADIUS-protokollet lämpar sig inte för större organisationer.Framtiden för Diameter är att anses som ljus. Diameter har rätt uppbackning från organisationer och marknaden i helhet för att bli det nästa stora AAA-protokollet. Diameter har även fått protokollet IMS anpassat efter sig och på så sett visar marknaden stort förtroende för Diameter-protokollet.
29

Laboratorní úloha CISCO Security / CISCO security laboratory exercise

Švec, Martin January 2009 (has links)
The main purpose of this diploma thesis is to become familiar with the principles and technical solutions regarding security components of Cisco company and configure assigned system according to valid rules of security. In introduction are explained the reasons for networks security solutions. This work also analyses different kinds of security weaknesses which include deficiencies of networks protocols and also the attacks from hackers. The principle of firewall is described and also its particular types. This work is focused on explanation and classification of PIX firewall, which has dominant role in the field of network security. The other equipments of Cisco, which are improving the level of security, are also mentioned. The practical part of this diploma thesis is composed of networks connections and configuration of system consisting of router, PIX firewall and switch. It also includes the detailed procedure and description of configuration of network equipments. The focus is put on minimalization of threats and elimination of DoS attacks.
30

Testovací implementace protokolu ACP / Test implementation of the ACP protocol

Ležák, Petr January 2012 (has links)
In general this master’s thesis deals with access control methods and their individual modules and in particular with authentication of supplicants. There are listed authentication methods useful in the implementation of the ACP protocol. ACP protocol is also discussed including possibilities and uses. ACP message format is described in detail with AVP format and types. The transaction mechanism is also mentioned here. The main part of the thesis is focused on software design for protocol testing. Possibilities of the testing are discussed and test scenarios are suggested. Consequently, requirements for test software are listed and its implementation is designed. Furthermore, there is technical documentation of the program. The main ideas used in the program are explained in it. The purpose of each part of the program is written including links between them. Finally, there is a manual for the program. It also contains an illustrative example describing how to make and test a simple scenario of the authentication.

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