Message-oriented middleware (MOM) is a middleware used for communication between applications. There are many different MOM technologies available today, each offering different performance (throughput and latency). The performance of MOMs depends on both message size and message guarantee settings used. The problem is that it can be difficult for users to know which MOM they should choose given their requirements. The goal was to create a performance (latency and throughput) comparison of three popular MOMs; Apache Kafka, RabbitMQ and Nats Streaming. The result shows that Kafka is the best performing MOM for smaller message sizes (under 512 bytes). RabbitMQ has the best performance for larger message sizes (over 32768 bytes). Nats Streaming only outperformed the other message system for a few combinations of message guarantee settings with the message size 4096 bytes. / Meddelandeorienterad mellanprogramvara (MOM) är mellanprogramvara som används för kommunikation mellan applikationer. Det finns många MOM system som erbjuder olika prestanda (genomströmning och latens). Prestandan är beroende av vilka meddelandegarantier som används samt meddelande storlek. Detta gör det svårt för användare att välja MOM utifrån sina krav. Målet är därför att jämföra tre populära MOMs; Apache Kafka, RabbitMQ och Nats Streaming. Resultaten visar att Kafka presterar bäst med små meddelandestorlekar (Under 512 bytes). RabbitMQ presterar bäst för större meddelanden (Över 32768 bytes) medans Nats Streaming enbart presterar bäst med ett begränsat antal meddelandegarantier och med en meddelandestorlek på 4096 bytes.

Small RNAs (sRNAs), circa 21-26nt RNA molecules, are a novel class of regulatory molecules that influence many aspects of plant biology. The first objective of this thesis was to utilize computational approaches both to investigate how microRNAs (miRNAs), a type of sRNA, as a class affect their target transcripts’ accumulation and to identify novel miRNAs in Arabidopsis thaliana. The second objective of this thesis was to examine the regulation of protein coding (PC) cis natural antisense transcripts (cis-NATs), which have the potential to make double stranded RNA. Computational analysis of the expression of miRNA-regulated genes demonstrated that the transcriptomes of the inflorescences of plants defective in miRNA biogenesis were similar to normal leaf tissues and dissimilar to normal pollen and seed. Thus, miRNAs cause the plant transcriptome to shift from a vegetative to reproductive state. Known miRNA targets fail to explain miRNA-defective mutant transcriptome patterns. Novel computational approaches were used to discover five new mature miRNAs. Interestingly, two miRNAs have different functions but are encoded by perfect complements of the same precursor molecule. Genome-wide analysis of cis-NAT abundances revealed that protein coding (PC) cis-NATs tend to be co-expressed, broadly expressed, and highly expressed across diverse abiotic stress conditions. These expression patterns were negatively associated with sRNAs because sRNAs were under-represented within PC cis-NATs compared to PC non-cis-NATs. sRNAs also mapped to cis-NATs and non-cis-NATs at similar frequencies in mutants defective in nat-siRNA biogenesis relative to other genotypes. We suggest a common euchromatin environment and possibly antisense RNA stabilization of mRNA transcripts may contribute to the high level, breadth, and co-expression of cis-NATs. However, cis-NATs are correlated less frequently than expected, and cis-NAT transcript abundances often differ more than expected. In addition, sRNAs matched PC cis-NATs relative to PC non-cis-NATs more frequently in abiotic stress conditions than in control conditions. Thus, although sRNAs do not have a widespread role in regulating cis-NATs, sRNAs may have a focused role in regulating cis-NAT transcript abundances. / PhD thesis / NSERC

This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.

Les systèmes pair-à-pair (P2P) sont aujourd'hui très populaires. Leur utilisation va de la messagerie instantanée au partage de fichiers, en passant par la sauvegarde et le stockage distribué ou encore le streaming video. Parmi les protocoles P2P, les protocoles basés sur le "gossip" sont une famille de protocoles qui a fait l'objet de nombreux travaux de recherche durant la dernière décennie. Les raisons de l'engouement pour les protocoles basés sur le "gossip" sont qu'ils sont considérés robustes, faciles à mettre en oeuvre et qu'ils ont des propriétés de passage à l'échelle intéressantes. Ce sont donc des candidats intéressants dès lors qu'il s'agit de réaliser des systèmes distribués dynamiques à large échelle. Cette thèse considère deux problématiques rencontrées lorsque l'on déploie des protocoles basé sur le "gossip" dans un environnement réel comme l'Internet. La première problématique est la prise en compte des pare-feux (NAT) dans le cadre des protocoles d'échantillonnage basés sur le "gossip". Ces protocoles font l'hypothèse que, a tout moment, chaque noeud est capable de communiquer avec n'importe quel noeud du réseau. Cette hypothèse est fausse dès lors que certains noeuds utilisent des NAT. Nous présentons Nylon, un protocole d'échantillonnage qui fonctionne malgré la présence de NAT. Nylon introduit un faible surcoût pour gérer les NAT et partage équitablement ce surcoût entre les noeuds possédant un NAT et les autres noeuds. La deuxième problématique que nous étudions est la possibilité de limiter la dissémination de messages de type "spam" dans les protocoles de dissémination basés sur le "gossip". Ces protocoles sont en effet des vecteurs idéaux pour diffuser les messages de type "spam" du fait qu'il n'y a pas d'autorité de contrôle permettant de filtrer les messages basés sur leur contenu. Nous proposons FireSpam, un protocole de dissémination basé sur le "gossip" qui permet de limiter la diffusion des messages de type "spam". FireSpam fonctionne par filtrage décentralisé (chaque noeud participe au filtrage). Par ailleurs, il fonctionne malgré la présence d'une fraction de noeuds malicieux (aussi appelés "Byzantins") et malgré la présence de noeuds dits “rationnels” (aussi appelés "égoïstes"). Ces derniers sont prêts à dévier du protocole s'ils ont un intérêt à le faire. / Peer-to-peer (P2P) systems are very popular today. Their usage goes from instant messaging to file sharing, from distributed backup and storage to even live-video streaming. Among P2P protocols, gossip-based protocols are a family of protocols which have been the object of several research works in the last decade. The reasons behind the interest in gossip-based protocols are that they are considered robust, easy to implement, and that they have interesting scalability properties. They are then appealing candidates for implementing dynamic and large-scale distributed systems. This thesis tackles two problems faced by gossip-based protocols when deployed on a practical scenario as the Internet. The first problem is coping with Network Address Translators (NATs) in the context of gossip-based peer sampling protocols. These protocols make the assumption that, at any moment, each node is able to communicate with any other node of the network. This assumption is false when some nodes use NATs. We present Nylon, a peer sampling protocol which works despite the presence of NATs. Nylon introduces a low overhead to cope with NATs and fairly balances this overhead among nodes using a NAT and those which do not. The second problem that we study is the possibility to limit the dissemination of “spam” messages in gossip-based dissemination protocols. These protocols are in fact ideal vectors to spread spam messages due to the fact that there is no central authority in charge of filtering messages based on their content. We propose FireSpam, a gossip-based dissemination protocol which allows limiting the dissemination of “spam” messages. FireSpam implements a decentralized filtering mechanism (each node participates to the filtering). Moreover, it works despite the presence of a fraction of malicious nodes (also called “Byzantine” nodes) and despite the presence of so called “rational” nodes (also called “selfish” nodes). These latters are willing to deviate from the protocol if they have an interest in doing so.