L'insuffisance surrénale primaire (ISP) se caractérise par un déficit en hormones stéroïdiennes lié à un trouble du cortex surrénal qui expose au risque d'insuffisance aiguë et de menace vitale. Actuellement, 80% des formes pédiatriques d'ISP sont d'origine génétique et 5% restent sans étiologie génétique identifiée. Les récentes découvertes de mutations de gènes du stress oxydant ouvrent le champ des recherches d'anomalies génétiques non spécifiques de la glande surrénale. Le séquençage parallèle massif (MPS) autorise aujourd'hui la réalisation de millions de séquences et l'étude simultanée de plusieurs gènes de plusieurs patients ce qui permet d'accélérer le diagnostic. C'est aussi la technique de choix pour la recherche de nouveaux gènes. Cependant, parmi les défis de cette nouvelle technologie, il est possible de citer la gestion de la très grande quantité de données qu'elle génère et le besoin d'une validation rigoureuse préalable à son utilisation à des fins diagnostiques.Le premier objectif du présent travail était d'établir un diagnostic génétique dans une cohorte de patients atteints d'ISP et de rechercher de nouveaux gènes. L'étude des génotypes et des phénotypes permet de comprendre les mécanismes physiopathologiques pour les engager dans le traitement et le conseil génétique.Le second objectif était le développement de méthodes bio-informatiques et d'inférence statistique pour faciliter le transfert du séquençage classique (Sanger) vers la technique MPS. Ce développement comprend l'analyse graphique de la qualité du séquençage, l'ajustement de modèles log-linéaires pour comparer les propriétés de différents « pipelines », et l'ajustement de modèles additifs généralisés pour estimer les contributions des sources d'erreurs de séquençage. Les analyses statistiques ont considéré chaque paire de bases comme unité statistique et chaque patient comme étude indépendante, ce qui confère à l'analyse simultanée de tous les patients le caractère d'une méta-analyse / Primary adrenal insufficiency (PAI) is characterized by an impaired production of steroid hormones due to an adrenal cortex defect. This condition exposes to the risk of acute insufficiency which may be life-threatening. Today, 80% of pediatric forms of PAI have a genetic origin but 5% have no clear genetic support. Recently discovered mutations in genes relative to the oxidative stress have opened the way to research works on genes unrelated to the adrenal gland. Massive Parallel Sequencing (MPS) is now able to perform millions of sequences and study simultaneously several genes in several patients, which accelerates the diagnosis. Above all, MPS is the preferred technique for new gene discoveries. However, among the challenges of this new technology one may cite the management of the huge amount of data MPS generates and the need for a strict validation process before the use of MPS for diagnosis purposes.The first objective of the present work was to establish a genetic diagnosis in a cohort of patients with PAI and search for new genes. Study the genotypes and phenotypes allows a better understanding of the physiopathological mechanisms of PAI and offering appropriate care for the patients and counseling for families. The second objective was the development of bioinformatic and statistical inference methods to help shifting from the classical Sanger sequencing to MPS. This shift involves a graphical analysis of the quality of sequencing, an adjustment of log-linear models to allow comparing the properties of different pipelines, an adjustment of the generalized additive models to allow estimating the contributions of various sources of sequencing errors. The statistical methods have considered each DNA base-pair as a statistical unit and each patient as a separate study which confers the simultaneous study of all patients the status of a meta-analysis

Orientador: Pedro Cunha de Holanda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T06:55:32Z (GMT). No. of bitstreams: 1 Sato_EduardoAkio_M.pdf: 2319995 bytes, checksum: fc82384c799d5812bf14a71fe2723e2d (MD5) Previous issue date: 2016 / Resumo: Nesta dissertação analiso como uma classe de modelos sugeridos para acomodar neutrinos massivos no modelo padrão, os assim chamados mecanismos seesaw, podem também resolver o problema de assimetria bariônica no universo. Os requisitos mínimos para uma geração dinâmica bem sucedida de assimetria bariônica, conhecidos como condições de Sakharov, são: não conservação de número bariônico, violação de simetria CP e ausência de equilíbrio térmico. Para mostrar que mecanismos seesaw respeitam estas regras, reviso alguns tópicos como: a violação de número bariônico através do processo de sphalerons, a teoria de violação de CP através de invariantes de base fraca e a mecânica estatística de não equilíbrio através da equação de Boltzmann. Como exemplo considero um cenário de mecanismo seesaw tipo I (3+3) com massas de neutrinos estéreis altamente hierárquicas. A assimetria observada impõe um limite inferior na massa dos neutrinos estéreis ($M_1 \geq 8.4 \times 10^{8} \; \text{GeV}$) e um limite superior na massa dos neutrinos ativos ($m_1 < 0.11 \; \text{eV}$), consistente com limites previamente obtidos na literatura / Abstract: In this dissertation I analyse how a class of models suggested to accommodate massive neutrinos in the standard model, the so-called seesaw mechanisms, can also solve the baryon asymmetry of the universe problem. The minimal requisites to a successful dynamical generation of baryon asymmetry, known as Sakharov's conditions, are: Non-conservation of baryon number, violation of CP symmetry and absence of thermal equilibrium. To show that seesaw mechanisms respect those rules, I review some topics such as: the standard model baryon non-conservation via sphalerons process, the theory of CP violation via weak-basis invariants and non-equilibrium statistical physics via Boltzmann equation. As a example I consider a type I (3+3) seesaw mechanism scenario with highly hierarchical sterile neutrino masses and the observed asymmetry impose a lower bound in the sterile neutrino masses ($M_1 \geq 8.4 \times 10^{8} \; \text{GeV}$) and a upper bound in the active neutrino masses ($m_1 < 0.11 \; \text{eV}$), consistent with limits previously obtained in the literature / Mestrado / Física / Mestre em Física / 1370441/2014 / CAPES

The aim of this paper is to use a cultural-hermeneutic methodology to investigate how meaning is constructed in a contemporary social situation (co-culturally) and to suggest the Christian concept incurvatus in se as a critical theological resource (counter-culturally). Central to this account is how to think theologically in a secular situation. It could also be understood as a habermasian translation of a christian experience of the human problem as curved into themselves (homo incurvatus in se) into a existential language for a (possibly) universal experience. I liken this curvedness to the pervasive individualism of today’s society and argue that meaning-making based on the idea of individual freedom can lead to a lack of meaning and existential emptiness.  To arrive at a discussion of incurvatus in se as a theologically critical resource for the study of existential emptiness, I analyze film, parenting and worship to get an idea of what a meaning-making process can look like in these examples. The result of this analysis suggests that by viewing these activities as something that points beyond themselves, rather than something that only reflects the subjective, they can play a meaning-making role.  In light of this result and the interpretation of the situation, I propose a concept of humans as homo incurvatus in se as contrast to an idealization of individual freedom and selfrealization. Overall, this study develops a excurvatus ex se approach that is constituted by conscious and critical meaning-making and argues further that a modified understanding of the human problem as curved into themselves can serve as an incentive, or even a primus motor, to seek meaning outside the subjective in a responsible way.

Debido a la plusvalía del suelo y al incremento poblacional en los distritos Top de Lima, los proyectos inmobiliarios se diseñan con un mayor número de sótanos para poder cubrir la demanda de estacionamientos. Por lo que en la presente investigación vamos a emplear la herramienta Value Stream Mapping para optimizar el proceso de excavación masiva. El Value Stream Mapping es una herramienta empleada en la industria manufacturera que pertenece a la filosofía Lean Manufacturing, esta herramienta consiste en identificar el flujo de la cadena de valor de cierta actividad y mediante un gráfico tener una visión completa del flujo de trabajo y de todos los procesos involucrados. Mediante este mapeo resultará mucho más sencillo identificar los procesos que no aportan valor a la actividad para luego aplicar mejoras y poder optimizar el proceso de excavación masiva. Para analizar el proceso de excavación masiva se utilizaron datos obtenidos de tres proyectos ubicados en Lima cuyas profundidades de excavación fueron de 3 y 4 anillos. El mapeo de estado actual de estos proyectos nos permitió realizar un diagnóstico general e identificar los procesos con mayores tiempos no productivos. Finalmente, se elabora un mapa de estado futuro considerando la propuesta de mejora para el proceso de eliminación con pasamano de dos excavadoras, se implementa la propuesta de mejora en un cuarto proyecto con una profundidad de excavación de 6 anillos, con los resultados obtenidos se justifica que empleando la herramienta de Value Stream Mapping se puede optimizar el proceso de excavación masiva. / Due to the increase in land value and population growth in the top districts of Lima, real estate projects are designed with a greater number of basements to meet the demand for parking. Therefore, in this research we are going to use the Value Stream Mapping tool to optimize the massive excavation process. Value Stream Mapping is a tool used in the manufacturing industry that belongs to the Lean Manufacturing philosophy, this tool consists of identifying the flow of the value chain of a certain activity and by means of a graphic to have a complete vision of the workflow and all the processes involved. Through this mapping it will be much easier to identify the processes that do not add value to the activity and then apply improvements to optimize the mass excavation process. To analyze the mass excavation process, data obtained from three projects located in Lima with excavation depths of 3 and 4 rings were used. The current state mapping of these projects allowed us to make a general diagnosis and identify the processes with the longest non-productive times. Finally, a future state mapping is elaborated considering the improvement proposal for the two-excavator handrail disposal process, the improvement proposal is implemented in a fourth project with an excavation depth of 6 rings, with the results obtained it is justified that using the Value Stream Mapping tool the massive excavation process can be optimized. / Tesis

A massive castings defects are examined in this doctoral thesis, specialise in steels passing through peritectic transformation. There are typical types of defects at massive steel castings, as contrasted to „ordinary“ internal and surface ones. For massive steel castings are typical defects under feeders like conchoidal fractures, segregations, microporesities, reoxidation products. Combination of Al and Zr is an ordinary final deoxidation of EOP and LF steel for castings in ŽĎAS a.s. foundry. The aim of Al + Zr combination was to both deep deoxidation by Al (decrease of bubbles risk) and denitrification by Zr (decrease of conchoidal fractures). This theses refute premission mentioned above and verified persisting risk of defects under massive feeders, even though Al + Zr deoxidation is used. A final deoxidation by increased amount of Al was examinated, in combination with other deoxidation agents. Castings had 11 [cm] maximal modulus, and occurence of conchoidal fracture, reoxidation products and primary austenite grain size was evaluated. A selected optimal final deoxidations (Al, Al+Ti, Al+Zr) as a result from experiment described above, were evaluated on castings with 15 [cm] maximal modulus. The result of experiment is, that is not possible to repeatedly produce massive steel casting using EOP metallurgical equipment without defects under feeders, despite of deoxidation and pouring temperature optimalization. The defect indications look like conchoidal fracture, but there are microporesity and impurities instead. Finally, castings with maximal modulus 15 [cm] were produced using so called secondary metallurgy (LF, VD). Secondary metallurgy allowed to both significant decrease of sulfur and degassing of melted metal. Only this metallurgical procedure guarantees production of heavy steel castings without typical defects under massive feeders

Cette thèse porte sur le problème du transport à la demande (TAD). Nous proposons trois approches décentralisées basées sur les systèmes multi-agents pour résoudre ce problème. La première approche multi-agent utilise l'algorithme A* afin de trouver une solution optimale dans un réseau routier caractérisé par des vitesses de voyage constantes. Des expérimentations sont effectuées sur le réseau routier d'une ville libanaise appelée Tripoli et de bons résultats sont obtenus. Cependant, dans une ville comme Tripoli, les vitesses de voyage dépendent fortement de la situation dynamique du trafic routier. Pour cette raison, la deuxième approche multi-agent massif vient remédier à la première en tenant compte de l'évolution du trafic. Le réseau routier est considéré comme dynamique déterministe. Il se caractérise par des vitesses de voyages dépendantes de la situation habituelle du trafic. Ces vitesses sont pré-calculées en se basant sur des connaissances historiques du trafic routier. Les résultats expérimentaux montrent que le nombre de clients insatisfaits est supérieur à 50 % si les vitesses sont considérées comme constantes. Or, les connaissances historiques ne suffisent pas pour refléter la situation réelle du trafic surtout en cas d'apparition d'un événement imprévu tel qu'un accident sur le réseau. Pour cela, une troisième approche multi-agent massif auto-organisé est proposée. Le réseau routier est considéré comme dynamique stochastique caractérisé par des vitesses de voyage dépendantes de la situation réelle du trafic. Cette approche représente l'organisation dynamique du trafic à son échelle en se basant sur des connaissances historiques du trafic et sur des informations du trafic en temps réel. Les trajectoires des véhicules et leurs durées sont calculées et recalculées en ligne à chaque fois qu'un événement imprévu perturbe la situation habituelle du trafic. Les résultats expérimentaux montrent que jusqu'à 39 % des clients seront insatisfaits si un accident routier n'est pas considéré durant le traitement de leurs demandes. Autrement, 50 % à 100 % de ces clients sont satisfaits. / This thesis addresses the problem of on-demand transport (ODT). We propose three decentralized approaches based on multi-agent systems to solve this problem. The first multi-agent approach uses the algorithm A* in order to find an optimal solution in a road network characterized by constant travel speeds. Experiments are carried out on the road network of a Lebanese city called Tripoli and good results are obtained. However, in a city like Tripoli, travel speeds depend heavily on the dynamic situation of road traffic. For this reason, the second multi-agent approach massif comes to remedy the first taking into account the evolution of traffic. The road network is considered as dynamic deterministic. It is characterized by travel speeds dependent on the usual traffic situation. These speeds are pre-calculated on the basis of historical knowledge of road traffic. The experimental results show that the number of dissatisfied customers is greater than 50 % if the speeds are considered to be constant. Nevertheless, historical knowledge is not sufficient to reflect the actual traffic situation, especially in case of an unexpected event (such as an accident) occurring on the network. For this, a self-organized massive multi-agent approach is proposed. The road network is considered as a dynamic stochastic characterized by travel speeds dependent on the actual traffic situation. This approach represents the dynamic organization of traffic on its scale based on historical traffic knowledge and real-time traffic information. Vehicle trajectories and their durations are calculated and recalculated online whenever an unexpected event disrupts the usual traffic situation. The experimental results show that up to 39 % of customers will be dissatisfied if a road accident is not considered during the processing of their demands. Otherwise, 50 % to 100 % of these customers are satisfied.

(Bulk) metallic glasses ((B)MGs) are known to exhibit the highest yield strength of any metallic material (up to 5GPa), and show an elastic strain at ambient conditions, which is about ten times larger than that of crystalline materials. Despite these intriguing mechanical properties, BMGs are not used as structural materials in service, so far. The major obstacle is their inherent brittleness, which results from severe strain localization in so-called shear bands. MGs fail due to formation and propagation of shear bands. A very effective way to attenuate the brittle behaviour is to incorporate crystals into the glass. The resulting BMG composites exhibit high strength as well as plasticity. Cu-Zr-Al-based BMG composites are special to that effect, since they combine high strength, plasticity and work-hardening. They are comprised of the glass and shape-memory B2 CuZr crystals, which can undergo a deformation-induced martensitic transformation. The work-hardening originates from the martensitic transformation and overcompensates the work-softening of the glass. The extent of the plasticity of BMG composites depends on the volume fraction, size and particularly on the distribution of the B2 CuZr crystals. Nowadays, it is very difficult, if not impossible to prepare BMG composites with uniformly distributed crystals in a reproducible manner by melt-quenching, which is the standard preparation method. Flash-annealing of BMGs represents a new approach to overcome this deficiency in the preparation of BMG composites and is the topic of the current thesis. Cu46Zr46Al8 and Cu44Zr44Al8Hf2Co2 BMGs were flash-annealed and afterwards investigated in terms of phase formation, crystallization kinetics and mechanical properties. Flash-annealing is a process, which is characterized by the rapid heating of BMGs to predefined temperatures followed by instantaneous quenching. A temperature-controlled device was succesfully developed and built. The Cu-Zr-Al-based BMGs can be heated at rates ranging between 16 K/s and about 200 K/s to temperatues above their melting point. Rapid heating is followed by immediate quenching where cooling rates of the order of 1000 K/s are achieved. As a BMG is flash-annealed, it passes the glass-transition temperature, Tg, and transforms to a supercooled liquid. Further heating leads to its crystallization and the respective temperature, the crystallization temperature, Tx, divides the flash-annealing of BMGs into two regimes: (1) sub-Tx-annealing and (2) crystallization. The structure of the glass exhibits free volume enhanced regions (FERs) and quenched-in nuclei. Flash-annealing affects both heterogeneities and hence the structural state of the glass. FERs appear to be small nanoscale regions and they can serve as initiation sites for shear bands. Flash-annealing of Cu-Zr-Al-based BMGs to temperatures below Tg leads to structural relaxation, the annihilation of FERs and the BMG embrittles. In contrast, the BMG rejuvenates, when flash-annealed to temperatures of the supercooled liquid region (SLR). Rejuvenation is associated with the creation of FERs. Compared to the as-cast state, rejuvenated BMGs show an improved plasticity, due to a proliferation of shear bands, which are the carrier of plasticity in MGs. Flash-annealing enables to probe the influence of the free volume in bulk samples on their mechanical properties, which could not be studied, yet. In addition, B2 CuZr nanocrystals precipitate during the deformation of flash-annealed Cu44Zr44Al8Hf2Co2 BMGs. Deformation-induced nanocrystallization does not occur for the present as-cast BMGs. Flash-annealing appears to stimulate the growth of quenched-in nuclei, which are subcritical in size and can also dissolve, once the BMG is heated to temperatures in the SLR. Rejuvenation represents a disordering process, whereas the growth of quenched-in nuclei is associated with ordering. There is a competition between both processes during flash-annealing. The ordering seems to lead to a “B2-like” clustering of the medium range of Cu44Zr44Al8Hf2Co2 BMGs with increasing heating duration. So far, there does not exist another method to manipulate the MRO of BMGs. If Cu44Zr44Al8Hf2Co2 BMGs are flash-annealed to temperatures near Tx, most likely compressive resiudal stresses develop near the surface, which is cooled faster than the interior of the BMG specimen. They hinder the propagation of shear bands and increase the plasticity of flash-annealed BMGs in addition to rejuvenation and deformation-induced nanocrystallization. If BMGs are heated to temperatures above Tx, they start to crystallize. Depending on the exact temperature to which the BMG is flash-annealed and subsequently quenched, one can induce controlled partial crystallization. Consequently, BMG composites can be prepared. Both Cu-Zr-Al-based BMGs are flash-annealed at various heating rates to study the phase formation as a function of the heating rate. In addition, Tg and Tx are identified for each heating rate, so that a continuous heating transformation diagram is constructed for both glass-forming compositions. An increasing heating rate kinetically constrains the crystallization process, which changes from eutectic (Cu10Zr7 and CuZr2) to polymorphic (B2 CuZr). If the Cu-Zr-Al-based BMGs are heated above a critical heating rate, exclusively B2CuZr crystals precipitate, which are metastable at these temperatures. Thus, flash-annealing of Cu46Zr46Al8 and Cu44Zr44Al8Hf2Co2 BMGs followed by quenching enables the preparation of B2 CuZr BMG composites. The B2 precipitates are small, high in number and uniformly distributed when compared to conventional BMG composites prepared by melt-quenching. Such composite microstructures allow the direct observation of crystal sizes and numbers, so that crystallization kinetics of deeply supercooled liquids can be studied as they are flash-annealed. The nucleation kinetics of devitrified metallic glass significantly diverge from the steady-state and at high heating rates above 90 K/s transient nucleation effects become evident. This transient nucleation phenomenon is studied experimentally for the first time in the current thesis. Once supercritical nuclei are present, they begin to grow. The crystallization temperature, which depends on the heating rate, determines the crystal growth rate. At a later stage of crystallization a thermal front traverses the BMG specimen. In levitation experiments, this thermal front is taken as the solid-liquid interface and its velocity as the steady-state crystal growth rate. However, the thermal front observed during flash-annealing, propagates through the specimen about a magnitude faster than is known from solidification experiments of levitated supercooled liquids. As microstructural investigations show, crystals are present in the whole specimen, that means far ahead of the thermal front. Therefore, it does not represent the solid-liquid interface and results from the collective growth of crystals in confined volumes. This phenomenon originates from the high density of crystals and becomes evident during the heating of metallic glass. It could be only observed for the first time in the current thesis due to the high temporal resolution of the high-speed camera used. The heating rate and temperature to which the BMG is flash-annealed determine the nucleation rate and the time for growth, respectively. The size and number of B2 CuZr crystals can be deliberately varied. Thus mechanical properties of B2 CuZr BMG composites can be studied as a function of the volume fraction and average distance of B2 particles. Cu44Zr44Al8Hf2Co2 BMG specimens were flash-annealed at a lower and higher heating rate (35 K/s and 180 K/s) to different temperatures above Tx and subsequently subjected to uniaxial compression. BMG composites prepared at higher temperatures show a lower yield strength and larger plastic strain due to the higher crystalline volume fraction. They not only exhibit plasticity in uniaxial compression, but also ductility in tension as a preliminary experiment demonstrates. Furthermore, nanocrystals precipitate in the amorphous matrix of BMG composites during deformation. They grow deformation-induced from quenched-in nuclei, which are stimulated during flash-annealing. In essence, flash-annealing of BMGs is capable of giving insight into most fundamental scientific questions. It provides a deeper understanding of how annealing affects the structural state of metallic glasses. The number and size of structural heterogeneities can be adjusted to prepare BMGs with improved plasticity. Furthermore, crystallization kinetics of liquids can be studied as they are rapidly heated. Transient nucleation effects arise during rapid heating of BMGs and they cannot be described using the steady-state nucleation rate. Therefore, an effective nucleation rate was introduced. Besides, the flash-annealing process rises the application potential of BMGs. The microstructure of BMG composites comprised of uniformly distributed crystals and the glass, can be reliably tailored. Thus, flash-annealing constitutes a novel method to design the mechanical properties of BMG composites in a reproducible manner for the first time. BMG composites, which exhibit high strength, large plasticitiy and as in the case of B2 CuZr BMG composites as well work-hardening behaviour, can be prepared, so that the intrinsic brittleness of monolithic BMGs is effectively overcome.

User Generated Content (UGC) has boosted a high popularity since the birth of a wide range of web services allowing the distribution of such user-produced media content, whose patterns vary from textual information, photo galleries to videos on site. The boom of Internet of Things and the newly released HTML5 accelerate the development of multimedia patterns as well as the technology of distributing it. YouTube, as one of the most popular video sharing site, enjoys the top most numbers of video views and video uploads per day in the world. With the rapid growing of multimedia patterns as well as huge bandwidth demand from subscribers, the sheer volume of the traffic is going to severely strain the network resources.&lt;/p&gt;&lt;p&gt;Therefore, analyzing media streaming traffic patterns and cacheability in live IP-access networks today leads a hot issue among network operators and content providers. One possible solution could be caching popular contents with a high replay rate in a proxy server on LAN border or in users' terminals.&lt;/p&gt;&lt;p&gt;Based on the solution, this thesis project focuses on developing a measurement framework to associate network cacheability with video category and video duration under a typical Swedish municipal network. Experiments of focused parameters are performed to investigate potential user behavior rules. From the analysis of the results, Music traffic gets a rather ideal network gain as well as a remarkable terminal gain, indicating that it is more efficient to be stored close to end user. Film&amp;amp;Animation traffic, however, is preferable to be cached in the network due to its high net gain. Besides, it is optimal to cache the video clips with a length between 3 and 5 minutes, especially the Music and Film&amp;amp;Animation traffic. In addition, more than half of the replays occur during 16.00-24.00 and peak hours appear on average from 18.00 to 22.00. Lastly, only around 16% of the videos are global popular and very few heavy users tend to be local popular video viewers, depicting local limits and independent user interests

Despite the growing expectation on corporate Learning &amp; Development (L&amp;D) units to transform practices and roles and take a more strategic role to better meet the needs of lifelong learning and up- and reskilling in organizations, many fail to use technology such as Massive Open Online Course (MOOC) platforms that could support the shift. The aim of this study is to provide a better understanding of why those in L&amp;D who are using MOOC platforms do so and what impact it has on the role of L&amp;D. Empirical data from in-depth interviews with six L&amp;D professionals, with extensive experience from large, global companies, has been employed in this exploratory research. The analysis imply a situation in which MOOC platforms, when used in organizations where employee language, literacy and digital devices are not a limitation, can support in meeting the needs of lifelong learning and up- and reskilling in ways not possible with traditional L&amp;D practices. The findings also indicate that while L&amp;D units in large, global organizations can transform traditional practices and roles and contribute strategically, with the support of MOOC platforms, they struggle to make full use of the platforms due to lack of prioritization in the organization. This could inhibit L&amp;D to fully take on a strategic role. Previous research has not explored the impact and possibilities the use of MOOC platforms can have specifically on the L&amp;D role. The findings provide a novel contribution to L&amp;D research as well as input to professionals in L&amp;D or Human Resource, business leaders, organizational developers and MOOC platform providers in decisions connected to digitalization of corporate learning.

In the last decade, development of Information and Communication Technology (ICT) thatsupports online learning has increased the demand for e-learning and Massive Open OnlineCourses (MOOCs). Despite their increased popularity, MOOCs are struggling with highdropout rates and only a small percentage of learners complete the courses they enrolled in. Thepurpose of this thesis is to gain knowledge about MOOC learner behaviour. The aim of thestudy is to identify the motivations of learners and how these differ between learners whocompleted a course and those who dropped out. Research on MOOC learners has mostly beencarried out using a quantitative approach. While quantitative methodologies are effective inhandling the large amount of data produced by MOOCs, qualitative methods can give deeperinsights into online learners’ motivations. Therefore, this thesis employs an explanatorysequential mixed methods research, in which sentiment analysis and topic modeling of learnerreviews from the platform Coursera are further explained by qualitative interviews with MOOClearners. In the study 28,000 reviews scraped from five courses within the fields of data sciencewere analyzed and ten interviews were held with learners who either completed, dropped outfrom or both completed and dropped out from a MOOC. In the quantitative analysis nine coursefactors were found that learners wrote about: content, delivery, assessment, learning experience,tools, video material, teaching style, instructor skills and course provider. In addition, eighteenthemes were yielded from the interviews: self-discipline, just for fun, certificates, personaldevelopment, knowledge, career, time, equipment, practical exercise, interaction, instructor,reality, structure, external material, cost, community, degree of difficulty and other. In thediscussion the empirical findings are reflected upon using the theoretical framework of theresearch and the literature review. The result does not reveal any differences in motivationsbetween learners who completed a course and those who dropped out, however, it does identifyfactors that caused learners’ to drop out and the topics that most negative learner reviews wereabout. This research contributes to the body of knowledge in the field of research on MOOClearner retention and motivations. The topic is relevant for research in education informaticsand for continued improvements in delivery of MOOCs.