1000 resultados para Mixing-demixing transition


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In this Thesis I discuss the dynamics of the quantum Brownian motion model in harmonic potential. This paradigmatic model has an exact solution, making it possible to consider also analytically the non-Markovian dynamics. The issues covered in this Thesis are themed around decoherence. First, I consider decoherence as the mediator of quantum-to-classical transition. I examine five different definitions for nonclassicality of quantum states, and show how each definition gives qualitatively different times for the onset of classicality. In particular I have found that all characterizations of nonclassicality, apart from one based on the interference term in the Wigner function, result in a finite, rather than asymptotic, time for the emergence of classicality. Second, I examine the diverse effects which coupling to a non-Markovian, structured reservoir, has on our system. By comparing different types of Ohmic reservoirs, I derive some general conclusions on the role of the reservoir spectrum in both the short-time and the thermalization dynamics. Finally, I apply these results to two schemes for decoherence control. Both of the methods are based on the non-Markovian properties of the dynamics.

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Prerequisites and effects of proactive and preventive psycho-social student welfare activities in Finnish preschool and elementary school were of interest in the present thesis. So far, Finnish student welfare work has mainly focused on interventions and individuals, and the voluminous possibilities to enhance well-being of all students as a part of everyday school work have not been fully exploited. Consequently, in this thesis three goals were set: (1) To present concrete examples of proactive and preventive psycho-social student welfare activities in Finnish basic education; (2) To investigate measurable positive effects of proactive and preventive activities; and (3) To investigate implementation of proactive and preventive activities in ecological contexts. Two prominent phenomena in preschool and elementary school years—transition to formal schooling and school bullying—were chosen as examples of critical situations that are appropriate targets for proactive and preventive psycho-social student welfare activities. Until lately, the procedures concerning both school transitions and school bullying have been rather problem-focused and reactive in nature. Theoretically, we lean on the bioecological model of development by Bronfenbrenner and Morris with concentric micro-, meso-, exo- and macrosystems. Data were drawn from two large-scale research projects, the longitudinal First Steps Study: Interactive Learning in the Child–Parent– Teacher Triangle, and the Evaluation Study of the National Antibullying Program KiVa. In Study I, we found that the academic skills of children from preschool–elementary school pairs that implemented several supportive activities during the preschool year developed more quickly from preschool to Grade 1 compared with the skills of children from pairs that used fewer practices. In Study II, we focused on possible effects of proactive and preventive actions on teachers and found that participation in the KiVa antibullying program influenced teachers‘ self-evaluated competence to tackle bullying. In Studies III and IV, we investigated factors that affect implementation rate of these proactive and preventive actions. In Study III, we found that principal‘s commitment and support for antibullying work has a clear-cut positive effect on implementation adherence of student lessons of the KiVa antibullying program. The more teachers experience support for and commitment to anti-bullying work from their principal, the more they report having covered KiVa student lessons and topics. In Study IV, we wanted to find out why some schools implement several useful and inexpensive transition practices, whereas other schools use only a few of them. We were interested in broadening the scope and looking at local-level (exosystem) qualities, and, in fact, the local-level activities and guidelines, along with teacherreported importance of the transition practices, were the only factors significantly associated with the implementation rate of transition practices between elementary schools and partner preschools. Teacher- and school-level factors available in this study turned out to be mostly not significant. To summarize, the results confirm that school-based promotion and prevention activities may have beneficial effects not only on students but also on teachers. Second, various top-down processes, such as engagement at the level of elementary school principals or local administration may enhance implementation of these beneficial activities. The main message is that when aiming to support the lives of children the primary focus should be on adults. In future, promotion of psychosocial well-being and the intrinsic value of inter- and intrapersonal skills need to be strengthened in the Finnish educational systems. Future research efforts in student welfare and school psychology, as well as focused training for psychologists in educational contexts, should be encouraged in the departments of psychology and education in Finnish universities. Moreover, a specific research centre for school health and well-being should be established.

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The starting point of this study is that the prevailing way to consider the Finnish IT industries and industry information often results in a limited and even skewed picture of the sector. The purpose of the study is to contribute and increase knowledge and understanding of the status, structure and evolution of the Finnish IT industries as well as the Finnish IT vendor field and competition. The focus is on software product and IT services industries which form a crucial part of all ICT industries. This study examines the Finnish IT sector from production (supply) as well as market (demand) perspective. The study is based on empirical information from multiple sources. Three research questions were formulated for the study. The first concerns the status of the Finnish IT industries considered by applying theoretical frameworks. The second research question targets at the basis for the future evolution of the Finnish IT industries and, finally, the third at the ability of the available definitions and indicators to describe the Finnish IT industries and IT markets. Major structural changes like technological changes and related innovations, globalization and new business models are drivers of the evolution of the IT industries. The findings of this study emphasize the significant role of IT services in the Finnish IT sector and in connection to that the ability to combine IT service skills, competences and practices with high level software skills also in the future. According to the study the Finnish IT enterprises and their customers have become increasingly dependent on global ecosystems and platforms, applications and IT services provided by global vendors. As a result, more IT decisions are made outside Finland. In addition, IT companies are facing new competition from other than IT industries bringing into market new substitutes. To respond to the new competition, IT firms seek growth by expanding beyond their traditional markets.. The changing global division of labor accentuates the need for accurate information of the IT sector but, at the same time, also makes it increasingly challenging to acquire the information needed. One of the main contributions of this study is to provide frameworks for describing the Finnish IT sector and its evolution. These frameworks help combine empirical information from various sources and make it easier to concretize the structures, volumes, relationships and interaction of both, the production and market side of the Finnish IT industry. Some frameworks provide tools to analyze the vendor field, competition and the basis for the future evolution of the IT industries. The observations of the study support the argument that static industry definitions and related classifications do not serve the information needs in dynamic industries, such as the IT industries. One of the main messages of this study is to emphasize the importance of understanding the definitions and starting points of different information sources. Simultaneously, in the structure and evolution of Finnish IT industries the number of employees has become a more valid and reliable measure than the revenue based indicators.

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Trypanosoma vivax outbreaks in beef cattle in the Pantanal region of Mato Grosso do Sul state, Brazil, causes relevant economical impact due to weight loss, abortion and mortality. Cattle moved from the Pantanal to adjacent areas of this ecosystem for breeding and fattening is a common feature. Therefore an epidemiological study on breeding cows in the transition area between Pantanal lowland and adjacent highlands of Mato Grosso do Sul was performed to determine the T. vivax infection dynamics and outbreak risk. Three experimental groups were formed: Group 1 consisted of cows parasitologically negative by the Woo test and in the enzyme-linked immunosorbent assay for T. vivax antibody detection (Tv-ELISA-Ab); Group 2 parasitologically negative and positive in the Tv-ELISA-Ab; and in Group 3 cows were parasitologically positive and with positive reactions in the Tv-ELISA-Ab. During 24 months, the cows' dislodgment between the above established groups was monitored by Woo test and Tv-ELISA-Ab exams. The tabanid population was also monitored and the highest number occurred during the rainy season. Although parasitemias were detected only in the first four samplings of the experimental period, the cows could be considered as trypanotolerant, because no clinical signs were observed. Despite the higher T. vivax incidence during the dry season, no disease symptoms were seen. Even though T. vivax epidemiological situation in the herd was characterized as endemic with seasonal variation, the probability of outbreaks was null within the conditions of the study.

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In this positioning paper transition management (TM) and the sustainable nutrient economy are addressed. We discuss TM from its scholarly origins in the 1990’s to its implementation as a comprehensive sector-wide policy program on sustainability in The Netherlands during the first decade of the 2000´s. Although the program was innovative and provoked a new approach to environmental policy and governance, the program at large failed to set the right conditions under which sustainable transition take place. Lessons from the Netherlands, both successful and less successful, are addressed in this positioning paper to inform Finnish governmental and knowledge institutes on how (not) to implement TM on environmental issues. When looking at sustainable nutrient economy the paper takes a historical view at how problems with nutrients (especially phosphates) were dealt with in the Netherlands during the post World War II era. This transition did not occur easily. In the agricultural sector environmental policies to prevent nutrient problems were not easily accepted, as large agricultural economic interests were at stake and the sector’s main actors were generally opposed to (radical) environmental transition. Currently, sustainable nutrient economy initiatives are starting to receive attention on the political agenda once again. In 2011 a sector- and chain-wide covenant was signed, showing that sustainable nutrient transition goals get commitment from stakeholders throughout the nutrient chain. We judge that TM provides useful elements that are applicable to Finnish governance modes to support sustainable nutrient economy transition. However, the Finnish government should be careful when implementing TM to prevent making the same mistakes the Dutch government made in previous years.

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Coherent vortices in turbulent mixing layers are investigated by means of Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES). Subgrid-scale models defined in spectral and physical spaces are reviewed. The new "spectral-dynamic viscosity model", that allows to account for non-developed turbulence in the subgrid-scales, is discussed. Pseudo-spectral methods, combined with sixth-order compact finite differences schemes (when periodic boundary conditions cannot be established), are used to solve the Navier- Stokes equations. Simulations in temporal and spatial mixing layers show two types of pairing of primary Kelvin-Helmholtz (KH) vortices depending on initial conditions (or upstream conditions): quasi-2D and helical pairings. In both cases, secondary streamwise vortices are stretched in between the KH vortices at an angle of 45° with the horizontal plane. These streamwise vortices are not only identified in the early transitional stage of the mixing layer but also in self-similar turbulence conditions. The Re dependence of the "diameter" of these vortices is analyzed. Results obtained in spatial growing mixing layers show some evidences of pairing of secondary vortices; after a pairing of the primary Kelvin-Helmholtz (KH) vortices, the streamwise vortices are less numerous and their diameter has increased than before the pairing of KH vortices.

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The business logic in the manufacturing industry has changed in the 21st century. In the current industrial market, manufacturers are driven to provide more comprehensive offerings that go beyond the traditional product-orientation by providing capacity and availability for their customers. From incidental merchandise, services have become the core of manufacturers’ offerings with long-lasting service agreements over the life-cycles of their products. This change is driven both by the need of providers to grow and gain competitive advantage and by increased customer demand caused by customers’ outsourcing trends. The three key drivers for manufacturers’ service strategies are outsourcing trends, saturation of the installed base, and commoditization in product markets. Thus, manufacturers focus on providing industrial solutions which are delivered through relational processes with customers by using solution-driven business models. In the management of marketing activities, this can be regarded as closer customer relationships, service-dominant business logic, and collaboration in solving customers’ problems. However, there are few studies on comprehensive conceptualizations of a solution offering that include different elements and their roles, especially in the context of capital goods industry. Also the transition process needs further studies in a real life context. This study explores the transition process of an industrial company from product to solution business and, as an aid to managing the solution business, explicates the structure and management of an industrial solution offering. There are two themes, the industrial transition process and industrial solution offering. Regarding the industrial transition process, the aim is to understand the supplier view on the process and its execution and to determine the challenges related to the transition process. The industrial solution offering is discussed by its elements and characteristics, as well as management. Furthermore, a special type of build-own-operate-transfer business model is presented and its suitability in the industrial context analyzed. The study includes findings achieved by qualitative methods and from four case companies. Based on the results, it is tentatively suggested that in the industrial solution business, the transition from product to solution business is not a linear project but an evolving process that varies according to customer needs, which suggests that companies need to possess an ability to develop new business models for different customer needs. The industrial solution offering is dynamic as it evolves in collaboration according to the prevailing and latent customer needs, which suggest restructuring of the organization from a product-centric to a customer-centric one. Furthermore, based on the findings, the concept of industrial solutions is defined as an ongoing relational process to satisfy a customer’s particular business or operational requirements, and the concept of industrial solution offering as an entity comprising the customized goods, services, collaboration, and finance needed to fulfill the industrial solution. Finally, the study offers several managerial implications for industrial managers involved in the transition and management of the solution business and its offering.

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Hydrogen stratification and atmosphere mixing is a very important phenomenon in nuclear reactor containments when severe accidents are studied and simulated. Hydrogen generation, distribution and accumulation in certain parts of containment may pose a great risk to pressure increase induced by hydrogen combustion, and thus, challenge the integrity of NPP containment. The accurate prediction of hydrogen distribution is important with respect to the safety design of a NPP. Modelling methods typically used for containment analyses include both lumped parameter and field codes. The lumped parameter method is universally used in the containment codes, because its versatility, flexibility and simplicity. The lumped parameter method allows fast, full-scale simulations, where different containment geometries with relevant engineering safety features can be modelled. Lumped parameter gas stratification and mixing modelling methods are presented and discussed in this master’s thesis. Experimental research is widely used in containment analyses. The HM-2 experiment related to hydrogen stratification and mixing conducted at the THAI facility in Germany is calculated with the APROS lump parameter containment package and the APROS 6-equation thermal hydraulic model. The main purpose was to study, whether the convection term included in the momentum conservation equation of the 6-equation modelling gives some remarkable advantages compared to the simplified lumped parameter approach. Finally, a simple containment test case (high steam release to a narrow steam generator room inside a large dry containment) was calculated with both APROS models. In this case, the aim was to determine the extreme containment conditions, where the effect of convection term was supposed to be possibly high. Calculation results showed that both the APROS containment and the 6-equation model could model the hydrogen stratification in the THAI test well, if the vertical nodalisation was dense enough. However, in more complicated cases, the numerical diffusion may distort the results. Calculation of light gas stratification could be probably improved by applying the second order discretisation scheme for the modelling of gas flows. If the gas flows are relatively high, the convection term of the momentum equation is necessary to model the pressure differences between the adjacent nodes reasonably.

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Ambitious energy targets set by EU put pressures to increase share of renewable electricity supply in this and next decades and therefore, some EU member countries have boosted increasing renewable energy generation capacity by implementing subsidy schemes on national level. In this study, two different change approaches to increase renewable energy supply and increase self-sufficiency of supply are assessed with respect to their impacts on power system, electricity market and electricity generation costs in Finland. It is obtained that the current electricity generation costs are high compared to opportunities of earnings from present-day investor’s perspective. In addition, the growth expectations of consumptions and the price forecasts do not stimulate investing in new generation capacity. Revolutionary transition path is driven by administrative and political interventions to achieve the energy targets. Evolutionary transition path is driven by market-based mechanisms, such as market itself and emission trading scheme. It is obtained in this study that in the revolutionary transition path operation of market-based mechanisms is distorted to some extent and it is likely that this path requires providing more public financial resources compared to evolutionary transition path. In the evolutionary transition path the energy targets are not achieved as quickly but market-based mechanisms function better and investment environment endures more stable compared to revolutionary transition path.

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The purpose of this work is to obtain a better understanding of behaviour of possible ultrasound appliance on fluid media mixing. The research is done in the regard to Newtonian and non-Newtonian fluids. The process of ultrasound appliance on liquids is modelled in COMSOL Multiphysics software. The influence of ultrasound using is introduced as waveform equation. Turbulence modelling is fulfilled by the k-ε model in Newtonian fluid. The modeling of ultrasound assisted mixing in non-Newtonian fluids is based on the power law. To verify modelling results two practical methods are used: Particle Image Velocimetry and measurements of mixing time. Particle Image Velocimetry allows capturing of velocity flow field continuously and presents detailed depiction of liquid dynamics. The second way of verification is the comparison of mixing time of homogeneity. Experimentally achievement of mixing time is done by conductivity measurements. In modelling part mixing time is achieved by special module of COMSOL Multiphysics – the transport of diluted species. Both practical and modelling parts show similar radial mechanism of fluid flow under ultrasound appliance – from the horn tip fluid moves to the bottom and along the walls goes back. Velocity profiles are similar in modelling and experimental part in the case of Newtonian fluid. In the case of non-Newtonian fluid velocity profiles do not agree. The development track of ultrasound-assisted mixing modelling is presented in the thesis.

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Intercellular communication may be regulated by the differential expression of subunit gap junction proteins (connexins) which form channels with differing gating and permeability properties. Endothelial cells express three different connexins (connexin37, connexin40, and connexin43) in vivo. To study the differential regulation of expression and synthesis of connexin37 and connexin43, we used cultured bovine aortic endothelial cells which contain these two connexins in vitro. RNA blots demonstrated discordant expression of these two connexins during growth to confluency. RNA blots and immunoblots showed that levels of these connexins were modulated by treatment of cultures with transforming growth factor-ß1. To examine the potential ability of these connexins to form heteromeric channels (containing different connexins within the same hemi-channel), we stably transfected connexin43-containing normal rat kidney (NRK) cells with connexin37 or connexin40. In the transfected cells, both connexin proteins were abundantly produced and localized in identical distributions as detected by immunofluorescence. Double whole-cell patch-clamp studies showed that co-expressing cells exhibited unitary channel conductances and gating characteristics that could not be explained by hemi-channels formed of either connexin alone. These observations suggest that these connexins can readily mix with connexin43 to form heteromeric channels and that the intercellular communication between cells is determined not only by the properties of individual connexins, but also by the interactions of those connexins to form heteromeric channels with novel properties. Furthermore, modulation of levels of the co-expressed connexins during cell proliferation or by cytokines may alter the relative abundance of different heteromeric combinations.