De nos jours, la manipulation d’objets à l’aide du champ magnétique se trouve au cœur de nombreuses innovations en nanotechnologies. D’autre part, et du fait de sa capacité d’actionner à très petite échelle, l’utilisation du champ magnétique en biologie et en médecine est en plein essor. En outre, les grandes avancées en matière de fabrication de micro-sources magnétiques ont permis la synthèse d’aimants de tailles micrométriques intégrables dans des microsystèmes microfluidiques comme les laboratoires sur puce, très à la mode à l’heure actuelle. Bien que la séparation de cellules marquées magnétiquement, à l’aide d’un macro-aimant permanent ou d’électroaimant est une tâche aujourd’hui bien maitrisée, le gradient de champ généré par ces sources magnétiques reste insuffisant pour l’isolement de cellules marquées avec une très faible quantité de nanoparticules magnétiques. La réduction de la taille des aimants, évoquée dans cette thèse, constitue une alternative prometteuse, permettant la génération d’énormes gradients de champ magnétique à l’échelle micrométrique. L’objectif de ce travail est donc d’étudier l’attraction de cellules faiblement marquées magnétiquement, sur des réseaux de micro-aimants permanents micro-structurés, dans le but de concevoir un dispositif microfluidique original intégrant des micro-sources magnétiques permanentes, autonomes et passives. / Nowadays, the magnetic field applications at the microscopic scale have been described by an increasing attention as magnetic sources. Moreover, they can be integrated directly in the microchip. Nevertheless, the process of manipulating magnetic micro objects remains a challenge since the generation of magnetic fields and field gradients is strong enough. Previous research has reported the use of microelectromagnets to create magnetic field gradients in order to manipulate biological objects. However, the use of permanent magnetic microstructures permits to avoid Joule heating issues inherent to the electromagnets. In addition, no energy source is required. The aim of this thesis is to study the influence of physico-chemical characteristics of iron oxide nanoparticles on the rate of endocytosis, using an array of micro-magnets. Most probably, the applications of this reserach can be directly related to the gene therapy and can occur in most basic genetic studies. Another part of this work consists of combining microfluidic and magnetic forces in order to develop a cell sorting micro-systems that can be integrated in lab-on-chip or MEMS.

La probabilité de défaillance d’une structure sous séisme est représentée à l’aide de « courbes de fragilité ». Pour les estimer, nous proposons d’enrichir une base de données pré-existante à l’aide du modèle de l’article de F. Poirion et I. Zentner, Stochastic model construction of natural hazards given experimental data, qui se fonde sur la représentation de Karhunen-Loève. Les signaux générés sont triés par classes d’indicateur de nocivité sismique à l’aide d’un algorithme de partitionnement de données. Malgré la ressemblance certaine que présentent plusieurs signaux simulés, et les conséquences que nous tirons de ce problème, ils sont soumis à la structure. Les signaux de réponses résultants sont eux aussi enrichis, en prenant en compte certaines incertitudes afin de construire un intervalle autour de la courbe. La méthode fonctionne pour tout indicateur de nocivité sismique, et permet de s’affranchir de plusieurs hypothèses simplificatrices courantes. Les caractéristiques du scénario sismique sont conservées lors de l’enrichissement, et le processus modélisant le mouvement du sol garde toute sa généralité. Notre démarche est validée d’abord sur un cas simple, puis sur un cas industriel. / The failure probability of a structure under earthquake is represented with « fragility curves ». To estimate them, we propose to enrich a pre-existing data basis using the model of the article Stochastic model construction of natural hazards given experimental data, written by F. Poirion et I. Zentner, which is based on the Karhunen-Loeve expansion. The generated signals are sorted by seismic indicator classes using a data partitioning algorithm. Despite the resemblance between some simulated signals, and the consequences we draw from this problem, the structure is submitted to them. The resulting response signals are also enriched, taking into account uncertainties to construct an interval around the curve. The method works for any seismic indicator, and overcomes several common simplifying assumptions. The characteristics of the seismic scenario are preserved during the enrichment, and the process modeling the ground motion retains its generality. Our approach is first validated on a simple case, then on an industrial case.

Trichloroethylene (TCE) is a toxic pollutant that has become a widespread problem by seeping into groundwater across the developed world. Clean-up of sites contaminated with TCE is extremely difficult due to the absence of an efficient and cost-effective method for clean-up. Bioremediation efforts include a variety of potential microbial candidates with various metabolic capabilities as clean up options of contaminated sites. Cupriavidus necator, a soil bacterium was found to possess the ability to degrade TCE via a phenol-dependent pathway. Previous research by Ayoubi and Harker (1998) created a strain (MM02) capable of constitutive TCE degradation but the underlying genetic alteration causing constitutive production of the phenol hydroxylase pathway (PHL) and TCE breakdown was poorly characterized. We attempted to gain further understanding of the alterations that occurred in the PHL pathway to cause TCE to break down and replicate constitutive TCE degradation in a new strain with reduced foreign elements that may be introduced into the environment. Strain MM02 possessing this constitutive degradation activity and strain MM01were sequenced and compared to discover the source of this variation. A 210 base-pair deletion in the beginning of the PHL operon was identified and is likely the cause of this altered activity. The new strain of C. necator (MM14) was created using traditional bacterial mating methods and included a cleanly introduced kanamycin resistance gene and its associated promoter which could drive constitutive expression of the PHL pathway. The TCE degradation abilities of strains MM01, MM02, and MM14 were evaluated through the TCE degradation assay and gas chromatography. We had difficulty accurately measuring the concentration of TCE due to its volatile nature and dramatically altered the method ultimately reducing variation and capturing TCE concentrations in assays. When accurate readings were obtained, none of the strains measured exhibited quantifiable TCE degradation activity when compared to controls. Our results showed .08% of the degradation by strain MM02 measured previously (P. J. Ayoubi, 1997). Based on our findings, we were unable to replicate the TCE degradation caused my MM02 and our genetically modified strain also failed to breakdown TCE.

The purpose of this study was to understand what knowledge and skills retired educators have and how these skills can be harnessed and utilised to benefit career development programmes in Botswana. The Tri-KCC conceptual model of career development was deductively and inductively developed from an interplay of the economics of knowledge management, the epistemology of constructivism, career psychology and gerontology. A mixed methods-sequential explanatory was used in this study, following assumptions of pragmatism. The participants of the study were retired educators in Botswana, with a convenience sample located in Gaborone. The participants had retired between 2000 and 2012. One hundred and eight participants (108), out of a sample of 200 responded to a survey questionnaire. Sixteen (16) participants from the survey formed focus group discussions of 5, 5 and 6 participants each. The participants were purposively selected through respondent directed and snowball techniques. The quantitative aspect of the study was conducted first, followed by the qualitative aspect. The quantitative phase helped to explore the concept of harnessing experiential knowledge of the retired educators. The survey questionnaire highlighted the following soft skills of retired educators: self-awareness and others-awareness, leadership, mentoring and counselling. The quantitative stage informed the qualitative stage during which the focus groups took place. Thus the qualitative phase had more weighting in the study. Quantitative data was analysed descriptively and inferentially, while thematic analysis was used for qualitative data. Results confirmed that retired educators have acquired a great wealth of knowledge and skills and that the success of being an educator is linked to both professional and personal identities. In addition, experiences that were meaningful to the retired educators were those where self-discovery boosted their self-esteem. Botswana is losing skilled resources to the early retirement age. In view of the findings, the Tri-KCC conceptual model was constructed to incorporate knowledge capture and management to guide practice. Career construction theory, through narratives of retired educators, was proposed to guide the practice of career development. Based on the results, it appears that an improved career development theory and practice that utilises retired professionals may not only benefit Botswana but other countries as well. / Thesis (PhD)--University of Pretoria, 2014. / tm2015 / Educational Psychology / PhD / Unrestricted

I den här studien har Swedish Matchs marknadsföring av produktlinjen ZYN undersökts, med fokus på marknadsföring genom gratisprover. Då produktkategorin nikotinpåsar inte regleras av Lag (2018:2088) om tobak och liknande produkter har Swedish Match helt andra möjligheter att marknadsföra ZYN än företagets tobaksprodukter. Syftet med studien var att undersöka fenomenet utifrån den teoretiska modellen Tri-component attitude model och undersöka hur gratisprover påverkar konsumenters attityd och framtida köpbeteende. Undersökningen genomfördes genom en kvantitativ metod där en elektronisk webbenkät skickades ut som gav 185 svar. Resultatet visade att gratisprovet inte hade någon effekt på den kognitiva delen, men den affektiva delen av attitydskapandet. Vidare visade resultatet att gratisprovet faktiskt hade en effekt på framtida konsumentbeteende. Slutsatserna som drogs i studien var att Tri-component attitude model inte var rätt teori för att studera fenomenet, att det gratisprovet påverkade den affektiva delen, men inte den kogntiva delen. Det resultatet bör dock ses som en indikator, och inte som en vetenskaplig sanning på grund av implikationer med vald teori och metod. Slutsatsen drogs också att det finns ett orsak-verkan samband mellan gratisprovet och framtida konsumentbeteende.

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In 1900, the Appalachian region of northeast Tennessee and southwest Virginia began to change. The inhabitants were dependent on the resources of the rural land, but the arrival of railroads spawned industrialization. Over the next several decades, families moved down from the mountains into the valley of East Tennessee as workers took jobs in the developing urban centers. Country stores, two-lane roads, and cornfields would eventually give way to cities, multi-lane highways, and new housing. The Tri-Cities—Kingsport, Johnson City, and Bristol—were starting to form. In this carefully documented book, Tom Lee uses archival material, newspapers, memoirs, and current scholarship in Appalachian studies to examine the economic changes that took place in the Tri-Cities region from 1900 to 1950. With modernization and urbanization, an urban-industrial strategy of economic development evolved. The entry of extractive industry into the mountains established the power of the urban elite to shape rural life. Local businessmen saw the route to financial strength in the recruitment of low-wage industry. Workers left struggling farms for factory jobs. This urban-rural relationship supported the Tri-Cities’ manufacturing economy and gave power to the area’s elite. The New Deal and the Second World War broadened this relationship as federal funding sustained the economy. The advantages of urban centers after decades of development left rural communities on the verge of disappearance and dependent on the jobs, opportunities, and economic vision of the cities. By 1950, the power of Appalachia’s elite over the people of the region had extended beyond urban boundaries and brought about the conditions necessary for the creation of the metropolitan Tri-Cities area of today. Readers will gain a better understanding of the complexity of modernization in Appalachia and the rural South from this engaging book. / https://dc.etsu.edu/etsu_books/1285/thumbnail.jpg

The hybridization between two complementary strands of nucleic acid is the basis for a number of applications in DNA and RNA analysis, including in vivo RNA monitoring, microarrays, SNPs detection, and so on. The short oligonucleotide probes form Watson/Crick base pairs (A-T and G-C) with the analyzed nucleic acid. Molecular beacon (MB) probe is one of the most advantageous tools for nucleic acid analysis in real-time. A traditional MB probe consists of a DNA strand folded in hairpin motif with a fluorophore attached to the 5'end and a quencher attached to the 3' end. The loop segment is complementary to the analytes. Upon hybridization to a complementary single-stranded nucleic acid, MB probe switches to the elongated conformation, which separates the fluorophore from the quencher, resulting in high fluorescence signal. However, DNA or RNA folded in hairpin motifs are difficult to analyze by a conventional MB probes. Inefficient formation of the duplex between the secondary analyte and the MB probe results in low or undetectable fluorescent signal. In this project, we developed a tripartite probe consisting of one MB probe and two adaptor strands to genotype single nucleotide polymorphism (SNPs) in DNA hairpin motifs in real-time fluorescent assays. Each adaptor strand contains a fragment complementary to the analyte and a fragment complementary to an MB probe. One adaptor strand hybridizes to the analyte and unwinds its secondary structure, and the other strand forms stable complex only with the fully complementary analyte sequence. The tri-component probe promises to simplify nucleic acid analysis at ambient temperatures in such application as in vivo RNA monitoring and isothermal detection of specific DNA/RNA targets.

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