Message brokers are the backbone of modern publish subscribe messaging systems. These brokers can degrade or fail for a variety of reasons. This research specifically looks at the detection, prediction and mitigation of bottlenecks in brokers. The message-oriented-middleware framework here uses either a cluster of brokers on a Local Area Network (LAN) or a federation of brokers on a Wide Area Network (WAN) to route messages, facilitate multicasting and ameliorate demand surges and geographically related faults. Sensors have been constructed to monitor brokers and controllers to run the bottleneck detection algorithms. An overlay manager controls broker and topic pairing. Each topic is assigned a primary and secondary broker. When a failure is predicted, the overlay manager routes messages from the failing broker by switching topics to its secondary broker(s). The application for bottleneck forecasting is to allow us to pre-empt a broker failure and hence reroute messages to other brokers to increase resilience and reliability. The key contributions of this research are an abstract model of message-oriented-middleware broker based on the Apache Qpid message broker coupled with the use of analytical autoregressive exogenous (ARX) models that describes the broker behaviour during bottleneck conditions. The Apache Qpid message broker is a message broker that implements the Advanced Message Queuing Protocol (AMQP) for publish-subscribe messaging. ARX models are autoregressive models where the output depends on the previous output as well as external stimuli. These components are integrated to produce a generalised technique for calibrating broker performance and detection of bottlenecks in the broker. This research show how models were initially constructed using a complete range of input data. As bottlenecks occur only when the broker is heavily loaded, input data during idle periods can cause corruption to the model fit. Models were constructed with segmented input data, with each segment covering the range of one peak period. The segmented input allows the modelling of the broker behaviour only when it is experiencing a bottleneck. The result of this is a much-improved fit of the predictive models. The work here is compared against previous work using Markov-chains for creating predictive models. The results of both approaches are compared and reported.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: leaves 68-73. / by Maryann McCall-Taylor. / M.C.P.

Thesis. 1978. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: p. 72. / M.Arch.A.S.

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH / Bibliography: leaves 61-63. / by Ralph Michael Nicosia-Rusin. / M.C.P.

Maternal behaviours are those that increase offspring survival. Estrogens affect maternal behaviour by activating Estrogen Receptors (ER) in the brain. Maternal brain plasticity was explored by characterizing the effects of exposure to a mixture of environmental pollutants on number of ERs. Following exposure to the toxicants during pregnancy and lactation, brains of female rats were collected, sectioned at 30 μm and immunohistochemistry for ERα performed. Immuno-positive cells in the mPOA, VTA and NAc were counted. A two way ANOVA revealed no main effect of Treatment on the number of immunopositive cells for all three brain regions. However, a significant difference between the High and Low Doses with the high dose reducing the number of ERα+ cells in the mPOA and VTA. Our work showcases the importance of studying the effects of multiple chemical co-exposures on the mother's brain, as maternal brain changes impact maternal behaviour consequently affecting offspring neurodevelopment.

Empresas e instituições de pesquisa nacionais e internacionais tem concentrado esforços no sentido de desenvolver e promover a implementação do padrão internacional ISO 11783, baseado no protocolo de comunicação digital CAN (Contoller Network Area), para integração de dispositivos em máquinas e implementos agrícolas. Nesse contexto, é apresentado o desenvolvimento e a aplicação de um modelo baseado no formalismo das redes de Petri como uma ferramenta de suporte para a análise e implantação de uma rede CAN em aplicações com tempos-críticos. O modelo foi elaborado no ambiente para edição e simulação DesignCPN, sendo que a simulação é utilizada para a análise do desempenho e do comportamento de uma rede CAN com diferentes configurações que será embarcada em um veículo autônomo agrícola (VAA). / Intemational and national research institutions and companies have focused efforts to develop and promote the implementation of the international standard ISO 11783, based upon the digital communication protocol CAN (Controller Area Network), in order to integrate devices in machines and agricultural implements. Therefore, it is presented the development and the application of a model based on Petri nets\' formalism as a tool for the support, analysis and accomplishment of a CAN bus in time-critical applications. The model was constructed in an environrnent for edition and sirnulation of colored Petri nets, the software DesignCPN. The sirnulation was used for the analysis of the behavior and the performance the CAN bus for several configurations, which will be embedded in an Autonomous Agricultural Vehicle (VAA).

A grandeza produto kerma-área (PKA) é importante para estabelecer níveis de referência em exames de radiologia diagnóstica. Essa grandeza pode ser obtida por meio de medidores do PKA. O uso desses medidores é fundamental para avaliar a dose de radiação em procedimentos radiológicos, além de ser um bom indicador para que os limites de dose na pele do paciente não sejam excedidos. Algumas vezes, esses medidores vêm acoplados a equipamentos de radiação X, o que dificulta sua calibração. Neste trabalho foi desenvolvida uma metodologia de calibração de medidores do PKA. O instrumento utilizado para este fim foi o Patient Dose Calibrator (PDC). Ele foi desenvolvido para ser utilizado como referência na verificação da calibração de medidores do PKA e kerma no ar usados na dosimetria de pacientes e para verificação da consistência e do comportamento de sistemas de controle de exposição automáticos. Por se tratar de um equipamento novo, que, no Brasil, ainda não é utilizado como equipamento de referência para calibração, foi realizado, também o controle de qualidade deste equipamento, com testes de caracterização, a calibração e a avaliação da dependência energética. Após os testes, ficou provado que o PDC pode ser utilizado como instrumento de referência para a calibração a ser realizada in situ, de forma que as características de cada equipamento de radiação X onde os medidores do PKA são utilizados sejam consideradas. A calibração foi, então, realizada com medidores do PKA portáteis e em um equipamento de radiologia intervencionista que possui um medidor do PKA acoplado. Os resultados foram bons e ficou provada a necessidade de calibração desses medidores e a importância da calibração in situ com um medidor de referência. / The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient\'s skin doesnt exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter.

The question of what constitutes a culture has often been answered in one phrase: shared knowledge. Recent developments in both the theory and mathematics of examining this shared cultural knowledge allow researchers to produce mathematical models of informants' knowledge and perceptions of the culture they belong to. Many studies in cognitive anthropology have utilized these theoretical and mathematical tools: the present research sought to integrate a research design (based on the theory and mathematics mentioned above) with a relatively new cultural domain: the culture of sports. Three main question pertaining to cultural knowledge were addressed in this research: 1) Did an informant's behavioral embeddedness in sports correspond to their cognitive embeddedness? 2) Did informants' behavioral embeddedness (as a qroup) affect their perceptions of the sports culture they belonqed to? 3) Did informants' coqnitive embeddedness (as a qroup) affect their perceptions of the sports culture they belonged to? Behavioral embeddedness was measured using an instrument that contained 96 bioqraphical variables primarily designed to investigate an informant's participation in sports. Cognitive embeddedness was measured using an instrument based on consensus theory. Subjects' perceptions (called "world view" in this study) of sports were based on their judgements of similarities and differences among 10 sports. These judgements were evoked by triadic analysis. Both consensus theory and triadic analysis followed the framework laid out in Romney and Weller's systematic Data Analysis. Sixty-six informants completed a self-administered survey containing the three parts mentioned above. Because of the nature of the sample used, this study was treated as an ethnography. It was hypothesized that a) behavioral and cognitive embeddedness were correlated and, b) more culturally embedded individuals would have more "sophisticated" perceptions of sports culture. The first hypothesis was not supported: only weak correlations were found between cognitive embeddedness and variables measuring behavioral embeddedness. For the second hypothesis, the exact opposite was found: the more culturally embedded groups of informants had less "sophisticated" perceptions of the sports culture they belonged to.

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