Analytic and computational micromechanics techniques based on the composite cylinders method and the finite element method, respectively, have been used to determine the effective coefficient of thermal expansion (CTE) of carbon nanotube-epoxy nanocomposites containing aligned nanotubes. Both techniques have been used in a parametric study of the influence of interphase stiffness and interphase CTE on the effective CTE of the nanocomposites.  For both the axial and transverse CTE of aligned nanotube nanocomposites with and without interphase regions, the computational and analytic micromechanics techniques were shown to give similar results.  The Mori-Tanka method has been used to account for the effect of randomly oriented fibers.   Analytic and computational micromechanics techniques have also been used to assess the effects of clustering and clustering with interphase on the effective CTE components.  Clustering is observed to have a minimal impact on the effective axial CTE of the nanocomposite and a 3-10%.  However, there is a combined effect with clustering and one of the interphase layers. / Master of Science

京都大学 / 0048 / 新制・論文博士 / 博士(地球環境学) / 乙第12828号 / 論地環博第8号 / 新制||地環||24(附属図書館) / 31315 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)准教授 西前 出, 教授 渡邉 紹裕, 教授 小方 登 / 学位規則第4条第2項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第19347号 / 地環博第140号 / 新制||地環||28(附属図書館) / 32349 / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)准教授 西前 出, 教授 星野 敏, 教授 小方 登 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

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Thesis advisor: Abhishek Chatterjee / Thesis advisor: Eranthie Weerapana / Over the past twenty years, the site-specific incorporation of unnatural amino acids (UAAs) into a target protein through genetic code expansion (GCE) has emerged as one of the foremost technologies to selectively modify proteins in their native cellular context. This technology relies on engineered aminoacyl-tRNA synthetase (aaRS)/tRNA pairs that are orthogonal to the host cells’ endogenous aaRS/tRNA pairs. Traditionally, scientists look towards evolutionarily distant domains of life to identify orthogonal aaRS/tRNA pairs that can be further engineered for GCE applications in the host system. For example, bacterial aaRS/tRNA pairs are used for GCE in eukaryotes. The directed evolution of orthogonal aaRS/tRNA pairs for eukaryotic GCE has been less fortuitous due to the cumbersome nature of established yeast-based selection platforms. Recently, our lab circumvented this platform-based limitation by developing “altered translational machinery” (ATM) Escherichia coli strains that enabled the directed evolution of bacterial aaRS/tRNA pairs for eukaryotic GCE applications. In the ATM-tyrosyl (ATMY) E. coli strain, reintroduction of the E. coli tyrosyl-tRNA (tRNAEcTyrCUA) as a nonsense suppressor led to cross-reactivity with the endogenous E. coli glutaminyl-tRNA synthetase (EcGlnRS), restricting the activity range of aaRSs that could be selected, ultimately diminishing the scope of incorporable UAAs. To recover the dynamic range of this platform, cross-reactivity of the tRNAEcTyrCUA was eliminated through directed evolution of the tRNA acceptor stem. This new, orthogonal tRNA revealed weak mutant aaRSs whose suppression efficiencies were boosted through additional rounds of directed evolution. Improved aaRS mutants exhibited higher solubility, thermal stability, and suppression efficiency than their predecessor. While the newly engineered, orthogonal tRNAEcTyrCUA gave access to novel aaRS/tRNA pairs for eukaryotic GCE, some notable UAAs were still missing that could be incorporated with the archaeal Methanococcus jannaschii tyrosyl-tRNA synthetase (MjTyrRS)/tRNA pair in bacteria. Following a systematic investigation into the discrepancy between the E. coli tyrosyl-tRNA synthetase (EcTyrRS)/tRNA and MjTyrRS/tRNA pairs, we found that it can be partially attributed to the low structural robustness of the EcTyrRS. This limitation was overcome by rationally designing chimeric TyrRSs composed of EcTyrRS and a structural homologue from the thermophilic bacterium Geobacillus stearothermophilus. The chimeric scaffolds demonstrated enhanced stability, activity, and resilience to destabilizing active site mutations, offering a potentially more attractive scaffold for GCE. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Syftet med detta arbete var att utreda varför ångledningen ÅM17 ledning(756-21101-3) flyttat på sig och med detta få fram en dokumentation av nuläget, en uppdaterad beräkningsmodell och en utförd dimensioneringskontroll. Vid eventuell identifiering av problemområden skulle även rekommenderade förbättringsförslag tas fram. Utredningen av ångledningen gjordes först med manuella beräkningar av kondensatmängden, termiska expansionen, reaktionskrafter på stöd och stödavstånd. Sedan utfördes dokumentation av ångledningen med fotografering och mätningar. Sist så användes beräkningsmjukvaran ROHR2 för att modellera den befintliga isometriritningen och med hjälp utav tidigare resultat av dokumentation även modeller utav kritiska områden på den befintliga ångledningen. Resultatet av dessa beräkningar och modelleringar var att stödkrafterna i fjäderupphängningarna i de manuella beräkningarna samt ROHR2 var över de tillåtna stödkrafterna. Sedan visade även resultatet i dokumentationen och mätningen att det skiljde sig mellan den befintliga ångledningen och isometriritningen på vissa områden. Sist så visade resultatet av ROHR2 beräkningarna att böjarna vid stöd 16 var överutnyttjade med en överutnyttjning av 104,4 % i modellen av isometriritningen. Slutsatsen av detta arbete var att fyra problemområden på ångledningen identifierades och följande rekommenderade åtgärder togs fram. ● Flytta det axiala stoppet från stöd 8 till stöd 9 för att den ska vara närmare där den termiska expansionen utgår ifrån, horisontellt spel på 10 mm negativt x-led och 14 mm positivt x-led ● Kapa ner längden innan vertikalen för att åtgärda hur mycket den sticker ut med ● Åtgärda det felplacerade axialstoppet vid stöd 13 ● Lägg till en schimsning vid stöd 16

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Rhinos are iconic species of ecological and economic importance in Africa. They represent their range states’ rich natural heritage. White rhinos, currently estimated at approximately 20, 000 animals, recovered from near extinction after heavy poaching and habitat destruction decimated numbers to 50 individuals in the 20th century. Between 1970 and 1992, black rhino numbers suffered a 96% reduction in Africa. Today, black rhino numbers are estimated between 5, 000 and 5, 500 individuals. Black and white rhinos are currently classified in IUCN’s Red List as Critically Endangered, and Near Threatened respectively. Very few studies investigate the potential effects of climate change on rhinos. Investigations on the cooperative impacts of anthropogenic activities and natural processes on the species are non-existent. We conducted a literature review to assess the status of rhino conservation. Potential climate change effects on the species’ probability of occurrence in five study parks in Africa were assessed using two IPCC-AR5 scenarios; RCPs, 4.5 and 8.5. Human influences on rhinos we evaluated based on urban expansion forecasted for the year 2030. Perceptions of communities surrounding Hlane Royal National Park in Swaziland towards rhino conservation were collected using questionnaires. Most of the interviewed community members expressed pro rhino conservation attitudes and interest in the prevention of poaching. We expect the changing climate to have negative effects on the occurrence probability of rhinos. Forecasts show urban land-cover expanding into areas surrounding rhino habitats by 2030. This could have implications in the creation of corridors to facilitate the dispersal of the species.

This Master's thesis project aims to investigate if Wikipedia's clickstream data can be used to improve the retrieval performance of information retrieval systems. The project is conducted under the assumption that a traversal between two article connects the two articles in regards to content. To extract useful terms out of the clickstream data, it needed to be structured so that it given a Wikipedia article it is possible to find all of the in-going or out-going article traversals.The project settled on using the clickstream data in an automatic query expansion approach.Two expansion methods were investigated, one based on expanding with full article title so that the context would be preserved, and the other expanded with individual terms from the article titles.The structure of the data and two proposed methods were evaluated using a set of queries and relevance judgments. The results of the evaluation shows that the method that expands with individual terms performed better than the full article title expansion method and that the individual term method managed to increase the MAP with 11.24%.  The expansion method was evaluated on two different query collections, and it was found that the proposed expansion method only improves the results where the average recall of the original queries are low.The thesis conclusion is that the clickstream can be used to improve retrieval performance for an information retrieval system. / Det här examensarbetets mål är att undersöka om Wikipedias klickströmsdata kan användas för att förbättra sökprestanda för informationsökningssystem. Arbetet har utförts under antagandet att en övergång mellan två artiklar på Wikipedia sammankopplar artiklarnas innehåll och är av intresse för användaren. För att kunna utnyttja klickströmsdatan krävs det att den struktureras på ett användbart sätt så att det givet en artikel går att se hur läsare har förflyttat sig ut eller in mot artikeln. Vi valde att utnyttja datamängden genom en automatisk sökfrågeexpansion. Två olika metoder togs fram, där den första expanderar sökfrågan med hela artikeltitlar medans den andra expanderar med enskilda ord ur en artikeltitel.Undersökningens resultat visar att den ordbaserade expansionsmetoden presterar bättre än metoden som expanderar med hela artikeltitlar. Den ordbaserade expansionsmetoden lyckades uppnå en förbättring för måttet MAP med 11.21%. Från arbetet kan man också se att expansionmetoden enbart förbättrar prestandan när täckningen för den ursprungliga sökfrågan är liten. Gällande strukturen på klickströmsdatan så presterade den utgående strukturen bättre än den ingående. Examensarbetets slutsats är att denna klickströmsdata lämpar sig bra för att förbättra sökprestanda för ett informationsökningssystem.