Caractérisation de l’interaction entre Pseudomonas aeruginosa et Staphylococcus aureus lors d’infections pulmonaires en fibrose kystique

Les complications les plus importantes retrouvées en fibrose kystique sont les infections pulmonaires chroniques. Staphylococcus aureus et Pseudomonas aeruginosa sont les deux microorganismes les plus prévalents. Malgré leur co-isolement fréquent des poumons de patients, P. aeruginosa est antagoniste envers S. aureus in vitro et inhibe sa croissance; ces pathogènes ne devraient donc vraisemblablement pas arriver à causer des infections mixtes comme ils le font. Il semble donc y avoir une incohérence entre les observations cliniques et celles effectuées dans le cadre de modèles expérimentaux au laboratoire. En effet, des co-isolats cliniques ayant persisté dans le temps lors d’infections mixtes ne démontrent pas l’antagonisme typiquement décrit. Les interactions des co-isolats cliniques ont donc été étudiée dans le cadre de mes travaux de maîtrise. Deux modèles de co-culture in vitro ont été établis afin de caractériser les isolats étudiés. Dans ces modèles, les co-isolats ont démontré une absence ou une diminution de leur antagonisme, comparativement aux souches prototypiques. Par la suite, un modèle d’infection pulmonaire animal a été établi afin de vérifier leur interaction dans un contexte plus proche de la condition des patients atteints de la fibrose kystique. Étonnamment, les co-isolats comme les souches antagonistes ont accentué la colonisation de S. aureus. Par l'étude de plusieurs infections expérimentales mixtes causées par P. aeruginosa et S. aureus, nous avons observé que plus l'infection des poumons par P. aeruginosa est importante, plus la colonisation par S. aureus semble être facilitée. Bien qu’aucun facteur de virulence spécifique de P. aeruginosa ni les facteurs transcriptionnels les plus importants à la virulence de S. aureus n’aient été identifiés comme explication à ce phénomène, la surexpression des protéines eucaryotes ICAM-1 et ITGA-5 par P. aeruginosa pourraient être impliquée dans l’adhésion et l’internalisation cellulaire de S. aureus. Ainsi, P. aeruginosa pourrait modifier l’environnement in vivo d’une façon bénéficiant à S. aureus. Cette étude donne une première explication à la co-colonisation fréquente de ces deux bactéries pathogènes dans le contexte des infections pulmonaires chez les sujets fibrose kystique

The influence of habitat composition and configuration on the genetic structure of the pitcher plant midge

A major question in landscape genetics is how habitat structure influences spatial patterns of genetic differentiation. In this study, I evaluate the relative importance and effects of aspects of habitat composition (habitat amount) and configuration (patch size and isolation) on the spatial genetic structure of the pitcher plant midge, Metriocnemus knabi, whose larvae are found exclusively within the water-filled leaves of pitcher plants (Sarracenia purpurea) in a system that is naturally patchy at multiple spatial scales (i.e., leaf, plant, cluster, bog). I estimated genetic differentiation (FST) among leaves, plants, and clusters using 11 microsatellite loci, and measured the amount of habitat, patch size, and patch isolation at each spatial scale. Multi-model inference analyses indicate that the amount of habitat in the surrounding landscape (i.e., bog) and broad-scale patch isolation are the strongest predictors of genetic differentiation at local spatial scales (i.e., plant, cluster), and habitat amount and isolation have an interactive effect on FST estimates at the broader bog scale. These results reinforce the value of considering how ecological and evolutionary processes (i.e., behaviour, dispersal, gene flow, drift) occurring across multiple spatial scales may influence patterns of genetic differentiation

Space Force Acquisition Occupational Competencies

Symposium PresentationApproved for public release; distribution is unlimited

Developing United States Space Force Acquisition Occupational Competencies

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumAs part of its competency-based talent management strategy, which is outlined in The Guardian Ideal (U.S. Space Force [USSF], 2021), the U.S. Space Force (USSF) is identifying foundational and occupational competencies. Foundational competencies are those with which all Guardians will demonstrate some level of proficiency. Occupational competencies (one set for each of the four Space Force occupations—intelligence, operations, cyber, and acquisitions) will be used to code each position within the USSF and to guide Guardian professional development. This paper outlines the challenges associated with identifying a set of acquisition occupational competencies for the USSF by documenting the planning, execution, and results of the Acquisition Occupational Competency Study held in January 2022. It is hoped that by capturing the USSF experience, other acquisition competency-related efforts can be informed.Approved for public release; distribution is unlimited

How to build upon sustainable entrepreneurial opportunities in developing economies

Circular economy has been promoted as an alternative to the linear production and consumption patterns prevalent since the industrial era. The implementation of circular economy has proceeded in multiple ways, with different leading actors, e.g. strong industry champions (bottom-up) or with strong government involvement (top-down) and different environmental and economic drivers. This dissertation focuses on the realization of circular economy in a developing economy where there is no strong champion to promote it. It is argued that sustainable entrepreneurship can be a key mechanism for the development of circular economy activity. A circular economy focused incubator can provide a mechanism to identify and develop circular opportunities and find nascent entrepreneurs interested in sustainable enterprise. First, a conceptual and theoretical framework is developed that modifies the traditional incubator to promote circular economy. The new incubator model engages additional actors to provide information needed to identify circular economy opportunities and provide support to develop solutions. Two main challenges are identified to implement this modified incubator in a developing economy. First, environmental data and information to support opportunity identification is often lacking, mainly due to weak institutional capacity. Second, it is not clear how to develop and organize a supportive network to nurture opportunities found within the economy. Strategies to address these challenges are explored via a case study of plastic flows in Trinidad and Tobago (T&T) - a small island with a developing economy. First, the problem of lack of data is addressed by leveraging data sources made for other purpose (trade and waste characterization) to develop a materials flow analysis (MFA) that supports circular economy planning. This methodology succeeds in in realizing a fine-grained, disaggregated material flows for plastics in T&T. Lessons from this MFA include a significant share of waste plastics arising from the packaging of imported products. This material flow is then used to recommend CE management strategies for plastics in the country. The resulting method is applicable to other nations with poor data on materials flows in manufacturing but rich trade and waste data To address the challenges with developing a network supporting the CE incubator, interviews are conducted with potential actors in T&T and analyzed using a grounded theory approach. A major result of the analysis is concerns on government participation raised by some actors. With refined understanding of the obstacles and motivations, recommendations are made on how a CE incubator can be built using local business associations and other actors

David et Goliath : L’équilibre fragile des relations énergétiques canado-américaines à l’aube de la création de Petro-Canada

During the 1970's and at the dawn of the 80's, the intervention of the Federal Government of Canada in the country's economic sector became more pronounced, thus following a Worldwide trend in that aspect. It is specially marked in the sector of energy where it supports the Canadianization objectives which run counter to foreign interests and investments, first and foremost american. This article gives an idea of the world context in which lies the choice for energy policies. It goes on to de scribe the evolution of these policies which firmly hinge on the North-South continental context. The objectives outlined in the National Energy Program cannot allow to ignore this essential variable, specially in the determination of means and measures to be used to further economic nationalism. Such are the pressures brought about, at the highest level, by the american administration under the presidency of Ronald Reagan

Improving the Knowledge-Based Expert System Lifecycle

Knowledge-based expert systems are used to enhance and automate manual processes through the use of a knowledge base and modern computing power. The traditional methodology for creating knowledge-based expert systems has many commonly encountered issues that can prevent successful implementations. Complications during the knowledge acquisition phase can prevent a knowledge-based expert system from functioning properly. Furthermore, the time and resources required to maintain a knowledge-based expert system once implemented can become problematic. There are several concepts that can be integrated into a proposed methodology to improve the knowledge-based expert system lifecycle to create a more efficient process. These methods are commonly used in other disciplines but have not traditionally been incorporated into the knowledge-based expert system lifecycle. A container-loading knowledge-based expert system was created to test the concepts in the proposed methodology. The results from the container-loading knowledge-based expert system test were compared against the historical records of thirteen container ships loaded between 2008 and 2011