Network management is a problem that faces designers and operators of any type of network. Conventional methods of capacity planning or configuration management are difficult to apply directly to networks that dynamically allocate resources, such as Asynchronous Transfer Mode (ATM) networks and emerging Internet Protocol (IP) networks employing Differentiated Services (DiffServ). This work shows a method to generically classify traffic in an ATM network such that capacity planning may be possible. These methods are generally applicable to other networks that support dynamically allocated resources. In this research, Call Detail Records (CDRs) captured from a ¡§live¡¨ ATM network were successfully classified into three traffic categories. The traffic categories correspond to three different video speeds (1152 kbps, 768 kbps, and 384 kbps) in the network. Further statistical analysis was used to characterize these traffic categories and found them to fit deterministic distributions. The statistical analysis methods were also applied to several different network planning and management functions. Three specific potential applications related to network management were examined: capacity planning, traffic modeling, and configuration management. / Master of Science

Asymmetric digital subscriber line (ADSL) is a broadband access technology capable of delivering large bandwidth over existing copper telephone line infrastructure. This research aims at characterizing and analyzing TCP/IP performance in presence of a new protocol stack (TCP/IP over PPP and ATM) being promoted for one of the ADSL network architectures. Using extensive simulations, we verify the adverse effects of asymmetric links on the performance of TCP and additional throughput degradation caused by the overhead at the AAL5- ATM layers. This study involves unidirectional as well as bi-directional data transfer using different traffic mixes including bursty and non-bursty types of traffic. Bi-directional data transfer over asymmetric links results in ACK compression wherein TCP acknowledgements (ACKs) get bunched together behind larger data packets, further exacerbating the effect of asymmetry on TCP performance. By implementing the simulation model for PPP encapsulation over AAL5, we characterize its effect in terms of throughput degradation and excessive delay. We quantify the improvement in the throughput obtained by delaying the TCP ACKs and by TCP/IP header compression. These techniques being effective for unidirectional traffic over asymmetric links, however, do not prove as effective when ATM enters the scenario or in presence of bi-directional data transfer. Further, we implemented a simulation model of the Smart ACK Dropper (SAD), a technique to regulate the flow of TCP ACKs. Considerable improvement in performance especially in the presence of unidirectional data transfer is achieved using the SAD technique. Although the improvement is to a lesser extent in the presence of bi-directional data traffic, SAD helps the network in quickly recovering from the impact of ACK compression. We also propose and implement certain customized queuing/scheduling and policing mechanisms to enable differentiated servicing of TCP ACKs and data packets, and mitigate the effect of ACK compression. While providing considerable TCP performance improvement in presence of SAD, custom queuing also allows fair sharing of bandwidth between TCP flows, unlike priority queuing, which starves the low priority flow. The committed access rate (CAR)policing scheme provides considerable performance improvement when used with SAD, and is especially useful when TCP ACKs compete with bursty data traffic over the slower upstream. / Master of Science

Nous avons voulu évaluer si les gènes CHE2, ATM et TP53, associés à un risque intermédiaire de cancer du sein, étaient soumis à une différence d'expression allélique (DEA). Nous avons étudié des lignées cellulaires lymphoblastiques (LCLs) dérivées de patientes à haut risque, négatives pour des mutations dans CRCA1 et BRCA2. Nous avons développé une méthode basée sur la "fusion haute-résolution" (High-resolution melting curve analysis, HRM) et l'utilisation d'une sonde d'hybridation fluorescente pour détecter de la DEA chez des individus hétérozygotes pour un SNP marqueur exonique. Cette méthode permet de corréler le signal fluorescent à la quantité relative des transcrits alléliques. Nous avons développé un outil d'analyse adapté aux besoins spécifiques de l'étude de la DEA par HRM. Dans nos échantillons, une DEA statistiquement significative a été identifiée pour le gène CHEK2, chez les porteurs de la mutation tronquante 1100delC. En revanche, en combinant les données du criblage mutationnel des gènes candidats et de l'étude de DEA, nous n'avons pas identifié de variant régulateur localisé en cis qui induirait de la DEA significative dans les gènes étudiés, dans le contexte de régulation transcriptionnelle propre aux LCLs proliférant librement. Nos résultats montrent que le HRM est une méthode sensible et précise pour mesurer de la DAE et qui peut être appliquée à d'autres tissus, mammaires ou sanguins. Ces derniers présentent un grand intérêt pour les études de criblage mutationnel à haut-débit cherchant à identifier des variants dysfonctionnels dans les régions régulatrices de gènes candidats. / We aimed to assess whether the breast-cancer intermediate-risk genes CHEK2, ATM ant TP53 were subject to differential allelic expression (DAE) in lymphoblastoid cell lines (LCLs) from high-risk breast cancer patients for whom no mutation in BRCA1 or BRCA2 had been identified.We implemented an assay based on high-resolution melting curve analysis (HRM) of single labeled fluorescent probes to detect allelic expression imbalance. The method relies on the distinction of the two alleles of an exonic marker SNP in heterozygous individuals with a fluorescent signal correlated to the relative abundance of each transcript. We developed an analysis tool for HRM data processing, specifically dedicated to DAE assessment. In our series, we found evidence for DAE for CHEK2, in carriers of the truncating mutation 1100delC. When combining mutation-screening data and assessment of DAE, we did not identify functional regulatory variant located in cis of the studied genes that would lead to DAE, in the transcriptional regulatory milieu of freely proliferating LCLs. Our results support that HRM is a method with high sensitivity and accuracy that can be used for DAE assessment. This approach can be applied to study breast and blood tissue samples. The latter would be of great interest for high-throughput mutation screening projects aiming to identify dysfunctional regulatory variants in candidate genes.

Com o recente desenvolvimento de tecnologias de redes de altas taxas de transmissão, tais como Asynchronous Transfer Mode (ATM), o problema da carência por largura de banda foi solucionado. A questão atual é a implementação de sistemas que suportem os protocolos ATM de forma nativa e integral. Atualmente tem-se utilizado aplicativos tradicionais baseados nos protocolos TCP(UDP)/IP no topo da pilha de protocolos ATM. Tal modelo traz redundâncias que implicam diretamente em aumento de overhead na comunicação. Muitos modelos têm sido desenvolvidos para levar de forma direta a aplicação os serviços ATM. O propósito deste trabalho foi comparar o desempenho de transmissões de dados utilizando os protocolos TCP(UDP)/IP sobre ATM com transmissões de dados no modo ATM nativo. Para tal, utilizamos a plataforma de pesquisa HARP do sistema operacional FreeBSD. Tal plataforma implementa o modelo Classical IP sobre ATM utilizando os serviços AAL5 e ainda fornece uma API para sockets ATM permitindo que uma aplicação tenha acesso direto a camada AALS. Testes de taxa de transmissão, perda de células, e atraso na rede, foram realizados com base na modificação de parâmetros relacionados à aplicação e sistema operacional, tais como tamanho da mensagem sendo transmitida e tamanho dos buffers de socket. / The solution for the lack of bandwidth was solved by the recent development of high speed networks technologies, such as Asynchronous Transfer Mode - ATM. The question now is the implementation of systems, which provide support for ATM protocols in an integral way. Nowadays, legacy network applications, based in TCP/IP protocols have been used on top of ATM protocol stack. Such approach generates redundances that have as consequence an increase in the communication overhead. Many models have been developed to provide ATM services directly to applications. The goal of this study was to evaluate the performance of data transfers comparing the TCP/IP protocols over ATM with the performance of data transfers in native ATM mode. The Host ATM Research Plataform (HARP) was utilized on the FreeBSD operating system. This plataform implements Classical IP over ATM, utilizing AAL5 services. Furthermore, it provides an API for ATM sockets, allowing that an application directly access the AAL5 services. Measurements of throughput and investigations about cell loss and delay were carried out altering parameters related to the application and operating system. The parameters adopted were message size and socket buffer sizes.

Made available in DSpace on 2016-08-10T10:38:41Z (GMT). No. of bitstreams: 1 ANA TERRA SILVA CARVALHO.pdf: 3772543 bytes, checksum: 17bcee93b3653febc978c253fa6cba7b (MD5) Previous issue date: 2012-05-18 / In Brazil, cervical cancer is the second most common among women. Radiation therapy is part of its interdisciplinary management, playing an important role in their loco regional control. The major challenge of modern medicine in radiotherapy is to develop predictive methods that can determine the level of radiosensitivity of the patient and the healthy surrounding tissue in order to individualize the prescribed radiation dose, to prevent severe side effects and promoting better local tumor control. This study evaluated the acute and chronic adverse effects on the skin, lower gastrointestinal tract and urinary tract of radiotherapy in 47 cervical cancer patients. Methods and Materials: Biological material was collected and DNA from peripheral blood was extracted of all patients studied. The fragments of TP53 and ATM were amplified to be sequenced, to verify if there are any polymorphisms witch could be responsible to the radiosensitivity of the patients. Results and Discussion: In a univariate analysis, the variable age was strongly associated with a risk of acute toxicity skin (p=0,023). Patients that received a high dose of external beam radiation and patients who have undergone brachytherapy, showed a significantly higher incidence of chronic urinary tract toxicity (p=0,031) and (p=0,019), respectively. The exchange G>A in the position 5557 of the ATM gene was significantly associated with the risk of acute lower gastrointestinal tract (p=0,008). There wasn t association between the other TP53 polymorphisms analyzed and the frequency of side effects (p>0,05). Our data revealed that patients who evolved significant association presented death (p=0,019) with the increase of chronic skin radiossensitivity. Conclusions: These observations corroborate the importance of investigating the genetic profile to predict adverse side effects in cervical cancer patients undergoing radiotherapy. These genes have an important role in DNA repair pathways and probably are capable of modifying the responses of normal tissues to radiotherapy. / No Brasil, o câncer cervical é o segundo mais comum entre as mulheres. A radioterapia faz parte do seu manejo interdisciplinar, desempenhando papel importante em seu controle loco regional. O grande desafio da medicina moderna em radioterapia é desenvolver métodos preditivos que possam determinar o grau de radiossensibilidade da paciente e dos tecidos adjacentes saudáveis, afim de individualizar a dose de radiação prescrita, prevenindo efeitos colaterais severos e promovendo um melhor controle tumoral local. Este estudo avaliou os efeitos adversos agudos e crônicos na pele, trato gastrointestinal inferior e trato urinário durante a radioterapia, em 47 pacientes de câncer do colo do útero. Material e Métodos: O DNA foi extraído do material biológico (sangue periférico) coletado de todas as pacientes estudadas. Os fragmentos de TP53 e ATM foram amplificados e em seguida sequenciados, afim de verificar se há qualquer polimorfismo que poderia ser responsável pela radiossensibilidade das pacientes. Resultados e Discussão: Por meio de uma análise univariada, a variável idade do diagnóstico se associou fortemente ao risco de desenvolvimento de toxicidade aguda da pele (p=0,023). Pacientes que receberam uma dose elevada de teleterapia e pacientes que foram submetidas a braquiterapia, mostraram uma incidência significativa de toxicidade crônica do trato urinário (p=0,031) e (p=0,019), respectivamente. A troca G>A na posição 5557 do gene ATM mostrou uma associação significativa com o risco de toxicidade aguda do trato gastrinstestinal inferior (p=0,008). Não houve associação entre os polimorfismos de TP53 analisados e a frequência de efeitos adversos (p>0,05). Nossos dados revelaram ainda que pacientes que evoluíram a óbito apresentaram associação significativa (p=0,019) com a o aumento de radiossensibilidade crônica da pele. Conclusão: Estas observações corroboram a importância de investigar o perfil genético para prever efeitos adversos em pacientes com câncer cervical submetidas a radioterapia. Esses genes têm um papel importante em vias de reparo de DNA e provavelmente são capazes de modificar as respostas dos tecidos normais para radioterapia.

Made available in DSpace on 2016-04-04T18:31:20Z (GMT). No. of bitstreams: 1 Alberto Lotito.pdf: 2153365 bytes, checksum: 3433c9bb5371bcce62f119c4593fe360 (MD5) Previous issue date: 2007-12-05 / This work intends to perform end-to-end traffic engineering through simulations in broadband multiprotocol networks and evaluate used parameters. We ve proposed and tested parameters used by the network administrator to dimension the action of an algorithm for Traffic Engineering. We dedicated special attention to IP networks interconnected to MPLS networks. Through simulations, we ve addressed questions of performance optimization, evaluating the network packet losses and compare the results with packet loss in the traditional OSPF network achieving improvements of up to 50%. This work contributes with improvements in traffic performance for real world networks, developing practical application since the traditional IP networks up to the present MPLS networks and also for mixed technologies. / Este trabalho tem como objetivos realizar simula??es de engenharia de tr?fego fim a fim em redes que trabalham com protocolos distintos e avaliar par?metros usados. Propusemos e testamos par?metros que servem para que o operador da rede dimensione a atua??o de um algoritmo para engenharia de tr?fego. Demos especial aten??o ?s redes que trabalham com IP interconectando-se a redes MPLS. Executando diversas simula??es, trabalhamos quest?es de melhoria de desempenho por meio de avalia??o da perda de pacotes nas redes testadas comparando-se os resultados com as tradicionais redes com protocolo OSPF e chegando a melhoria de at? 50% se comparado com este. Este trabalho contribui com melhorias em engenharia de tr?fego em redes do mundo real, desenvolvendo aplica??o pr?tica desde as tradicionais redes IP at? as atuais redes MPLS e tamb?m em redes de tecnologias mistas.

Com o recente desenvolvimento de tecnologias de redes de altas taxas de transmissão, tais como Asynchronous Transfer Mode (ATM), o problema da carência por largura de banda foi solucionado. A questão atual é a implementação de sistemas que suportem os protocolos ATM de forma nativa e integral. Atualmente tem-se utilizado aplicativos tradicionais baseados nos protocolos TCP(UDP)/IP no topo da pilha de protocolos ATM. Tal modelo traz redundâncias que implicam diretamente em aumento de overhead na comunicação. Muitos modelos têm sido desenvolvidos para levar de forma direta a aplicação os serviços ATM. O propósito deste trabalho foi comparar o desempenho de transmissões de dados utilizando os protocolos TCP(UDP)/IP sobre ATM com transmissões de dados no modo ATM nativo. Para tal, utilizamos a plataforma de pesquisa HARP do sistema operacional FreeBSD. Tal plataforma implementa o modelo Classical IP sobre ATM utilizando os serviços AAL5 e ainda fornece uma API para sockets ATM permitindo que uma aplicação tenha acesso direto a camada AALS. Testes de taxa de transmissão, perda de células, e atraso na rede, foram realizados com base na modificação de parâmetros relacionados à aplicação e sistema operacional, tais como tamanho da mensagem sendo transmitida e tamanho dos buffers de socket. / The solution for the lack of bandwidth was solved by the recent development of high speed networks technologies, such as Asynchronous Transfer Mode - ATM. The question now is the implementation of systems, which provide support for ATM protocols in an integral way. Nowadays, legacy network applications, based in TCP/IP protocols have been used on top of ATM protocol stack. Such approach generates redundances that have as consequence an increase in the communication overhead. Many models have been developed to provide ATM services directly to applications. The goal of this study was to evaluate the performance of data transfers comparing the TCP/IP protocols over ATM with the performance of data transfers in native ATM mode. The Host ATM Research Plataform (HARP) was utilized on the FreeBSD operating system. This plataform implements Classical IP over ATM, utilizing AAL5 services. Furthermore, it provides an API for ATM sockets, allowing that an application directly access the AAL5 services. Measurements of throughput and investigations about cell loss and delay were carried out altering parameters related to the application and operating system. The parameters adopted were message size and socket buffer sizes.

Neste trabalho é proposta a modelagem de uma ferramenta de auxílio à tomada de decisão com base na avaliação do nível de perigo de colisão entre duas aeronaves em operação de aproximação em pistas de aterrissagem paralelas (UCSPA - Ultra Closely Spaced Parallel Approaches). A ferramenta computacional utilizada na simulação e na obtenção dos dados numéricos está fundamentada no Método de Monte Carlo. / In this work is proposed an aid tool modeling for decision-making process based on collision hazard evaluation between two aircrafts on UCSPA (Ultra Closely Spaced Parallel Approaches) scenario. The computation tool used in the simulation to obtain the numerical data is based on Monte Carlo Method.

Neste trabalho é proposta a modelagem de uma ferramenta de auxílio à tomada de decisão com base na avaliação do nível de perigo de colisão entre duas aeronaves em operação de aproximação em pistas de aterrissagem paralelas (UCSPA - Ultra Closely Spaced Parallel Approaches). A ferramenta computacional utilizada na simulação e na obtenção dos dados numéricos está fundamentada no Método de Monte Carlo. / In this work is proposed an aid tool modeling for decision-making process based on collision hazard evaluation between two aircrafts on UCSPA (Ultra Closely Spaced Parallel Approaches) scenario. The computation tool used in the simulation to obtain the numerical data is based on Monte Carlo Method.

Der Asynchronous Transfer Mode (ATM) stellt die zukünftige und einheitliche Basistechnologie für das Breitband-ISDN dar. Da nahezu alle wesentlichen Protokollfunktionen in Hardware realisierbar sind, soll nachfolgend ein Überblick über bereits angebotene VLSI-Schaltkreise gegeben werden. Eine Systematisierung und Einordnung vorhandener ATM-Chips hinsichtlich ihrer Leistungsfähigkeit und ihres Funktionsumfangs erfolgt in Hinblick auf das sogenannte B-ISDN-Referenzmodell. Dieses Schichtenmodell definiert die notwendigen Protokolle und Schnittstellen für den Asynchronous Transfer Mode. Zum grundlegenden Verständnis wird einleitend eine kurze Einführung in die Basisprinzipien von ATM gegeben.