Iterative reconstruction in CT : using mathematical model observers to determine low dose images' trustworthiness

La tomodensitométrie (TDM) est une technique d'imagerie pour laquelle l'intérêt n'a cessé de croitre depuis son apparition au début des années 70. De nos jours, l'utilisation de cette technique est devenue incontournable, grâce entre autres à sa capacité à produire des images diagnostiques de haute qualité. Toutefois, et en dépit d'un bénéfice indiscutable sur la prise en charge des patients, l'augmentation importante du nombre d'examens TDM pratiqués soulève des questions sur l'effet potentiellement dangereux des rayonnements ionisants sur la population. Parmi ces effets néfastes, l'induction de cancers liés à l'exposition aux rayonnements ionisants reste l'un des risques majeurs. Afin que le rapport bénéfice-risques reste favorable au patient il est donc nécessaire de s'assurer que la dose délivrée permette de formuler le bon diagnostic tout en évitant d'avoir recours à des images dont la qualité est inutilement élevée. Ce processus d'optimisation, qui est une préoccupation importante pour les patients adultes, doit même devenir une priorité lorsque l'on examine des enfants ou des adolescents, en particulier lors d'études de suivi requérant plusieurs examens tout au long de leur vie. Enfants et jeunes adultes sont en effet beaucoup plus sensibles aux radiations du fait de leur métabolisme plus rapide que celui des adultes. De plus, les probabilités des évènements auxquels ils s'exposent sont également plus grandes du fait de leur plus longue espérance de vie. L'introduction des algorithmes de reconstruction itératifs, conçus pour réduire l'exposition des patients, est certainement l'une des plus grandes avancées en TDM, mais elle s'accompagne de certaines difficultés en ce qui concerne l'évaluation de la qualité des images produites. Le but de ce travail est de mettre en place une stratégie pour investiguer le potentiel des algorithmes itératifs vis-à-vis de la réduction de dose sans pour autant compromettre la qualité du diagnostic. La difficulté de cette tâche réside principalement dans le fait de disposer d'une méthode visant à évaluer la qualité d'image de façon pertinente d'un point de vue clinique. La première étape a consisté à caractériser la qualité d'image lors d'examen musculo-squelettique. Ce travail a été réalisé en étroite collaboration avec des radiologues pour s'assurer un choix pertinent de critères de qualité d'image. Une attention particulière a été portée au bruit et à la résolution des images reconstruites à l'aide d'algorithmes itératifs. L'analyse de ces paramètres a permis aux radiologues d'adapter leurs protocoles grâce à une possible estimation de la perte de qualité d'image liée à la réduction de dose. Notre travail nous a également permis d'investiguer la diminution de la détectabilité à bas contraste associée à une diminution de la dose ; difficulté majeure lorsque l'on pratique un examen dans la région abdominale. Sachant que des alternatives à la façon standard de caractériser la qualité d'image (métriques de l'espace Fourier) devaient être utilisées, nous nous sommes appuyés sur l'utilisation de modèles d'observateurs mathématiques. Nos paramètres expérimentaux ont ensuite permis de déterminer le type de modèle à utiliser. Les modèles idéaux ont été utilisés pour caractériser la qualité d'image lorsque des paramètres purement physiques concernant la détectabilité du signal devaient être estimés alors que les modèles anthropomorphes ont été utilisés dans des contextes cliniques où les résultats devaient être comparés à ceux d'observateurs humain, tirant profit des propriétés de ce type de modèles. Cette étude a confirmé que l'utilisation de modèles d'observateurs permettait d'évaluer la qualité d'image en utilisant une approche basée sur la tâche à effectuer, permettant ainsi d'établir un lien entre les physiciens médicaux et les radiologues. Nous avons également montré que les reconstructions itératives ont le potentiel de réduire la dose sans altérer la qualité du diagnostic. Parmi les différentes reconstructions itératives, celles de type « model-based » sont celles qui offrent le plus grand potentiel d'optimisation, puisque les images produites grâce à cette modalité conduisent à un diagnostic exact même lors d'acquisitions à très basse dose. Ce travail a également permis de clarifier le rôle du physicien médical en TDM: Les métriques standards restent utiles pour évaluer la conformité d'un appareil aux requis légaux, mais l'utilisation de modèles d'observateurs est inévitable pour optimiser les protocoles d'imagerie. -- Computed tomography (CT) is an imaging technique in which interest has been quickly growing since it began to be used in the 1970s. Today, it has become an extensively used modality because of its ability to produce accurate diagnostic images. However, even if a direct benefit to patient healthcare is attributed to CT, the dramatic increase in the number of CT examinations performed has raised concerns about the potential negative effects of ionising radiation on the population. Among those negative effects, one of the major risks remaining is the development of cancers associated with exposure to diagnostic X-ray procedures. In order to ensure that the benefits-risk ratio still remains in favour of the patient, it is necessary to make sure that the delivered dose leads to the proper diagnosis without producing unnecessarily high-quality images. This optimisation scheme is already an important concern for adult patients, but it must become an even greater priority when examinations are performed on children or young adults, in particular with follow-up studies which require several CT procedures over the patient's life. Indeed, children and young adults are more sensitive to radiation due to their faster metabolism. In addition, harmful consequences have a higher probability to occur because of a younger patient's longer life expectancy. The recent introduction of iterative reconstruction algorithms, which were designed to substantially reduce dose, is certainly a major achievement in CT evolution, but it has also created difficulties in the quality assessment of the images produced using those algorithms. The goal of the present work was to propose a strategy to investigate the potential of iterative reconstructions to reduce dose without compromising the ability to answer the diagnostic questions. The major difficulty entails disposing a clinically relevant way to estimate image quality. To ensure the choice of pertinent image quality criteria this work was continuously performed in close collaboration with radiologists. The work began by tackling the way to characterise image quality when dealing with musculo-skeletal examinations. We focused, in particular, on image noise and spatial resolution behaviours when iterative image reconstruction was used. The analyses of the physical parameters allowed radiologists to adapt their image acquisition and reconstruction protocols while knowing what loss of image quality to expect. This work also dealt with the loss of low-contrast detectability associated with dose reduction, something which is a major concern when dealing with patient dose reduction in abdominal investigations. Knowing that alternative ways had to be used to assess image quality rather than classical Fourier-space metrics, we focused on the use of mathematical model observers. Our experimental parameters determined the type of model to use. Ideal model observers were applied to characterise image quality when purely objective results about the signal detectability were researched, whereas anthropomorphic model observers were used in a more clinical context, when the results had to be compared with the eye of a radiologist thus taking advantage of their incorporation of human visual system elements. This work confirmed that the use of model observers makes it possible to assess image quality using a task-based approach, which, in turn, establishes a bridge between medical physicists and radiologists. It also demonstrated that statistical iterative reconstructions have the potential to reduce the delivered dose without impairing the quality of the diagnosis. Among the different types of iterative reconstructions, model-based ones offer the greatest potential, since images produced using this modality can still lead to an accurate diagnosis even when acquired at very low dose. This work has clarified the role of medical physicists when dealing with CT imaging. The use of the standard metrics used in the field of CT imaging remains quite important when dealing with the assessment of unit compliance to legal requirements, but the use of a model observer is the way to go when dealing with the optimisation of the imaging protocols.

Non-Linear Journal Bearing Model for Analysis of Superharmonic Vibrations of Rotor Systems

A rotating machine usually consists of a rotor and bearings that supports it. The nonidealities in these components may excite vibration of the rotating system. The uncontrolled vibrations may lead to excessive wearing of the components of the rotating machine or reduce the process quality. Vibrations may be harmful even when amplitudes are seemingly low, as is usually the case in superharmonic vibration that takes place below the first critical speed of the rotating machine. Superharmonic vibration is excited when the rotational velocity of the machine is a fraction of the natural frequency of the system. In such a situation, a part of the machine’s rotational energy is transformed into vibration energy. The amount of vibration energy should be minimised in the design of rotating machines. The superharmonic vibration phenomena can be studied by analysing the coupled rotor-bearing system employing a multibody simulation approach. This research is focused on the modelling of hydrodynamic journal bearings and rotorbearing systems supported by journal bearings. In particular, the non-idealities affecting the rotor-bearing system and their effect on the superharmonic vibration of the rotating system are analysed. A comparison of computationally efficient journal bearing models is carried out in order to validate one model for further development. The selected bearing model is improved in order to take the waviness of the shaft journal into account. The improved model is implemented and analyzed in a multibody simulation code. A rotor-bearing system that consists of a flexible tube roll, two journal bearings and a supporting structure is analysed employing the multibody simulation technique. The modelled non-idealities are the shell thickness variation in the tube roll and the waviness of the shaft journal in the bearing assembly. Both modelled non-idealities may cause subharmonic resonance in the system. In multibody simulation, the coupled effect of the non-idealities can be captured in the analysis. Additionally one non-ideality is presented that does not excite the vibrations itself but affects the response of the rotorbearing system, namely the waviness of the bearing bushing which is the non-rotating part of the bearing system. The modelled system is verified with measurements performed on a test rig. In the measurements the waviness of bearing bushing was not measured and therefore it’s affect on the response was not verified. In conclusion, the selected modelling approach is an appropriate method when analysing the response of the rotor-bearing system. When comparing the simulated results to the measured ones, the overall agreement between the results is concluded to be good.

Revisió del model inclusiu en l’àmbit de l’educació no formal del futbol base a partir del criteri d’agrupació

Recerca centrada en l’anàlisi de característiques concretes de l’educació inclusiva en un entorn d’educació no formal, com és el futbol base. El criteri que s’ha utilitzat per realitzar l’anàlisi són els agrupaments. Des de l’educació inclusiva es promouen els agrupaments heterogenis, una forma d’agrupar a l’alumnat tenint en compte les seves diferències, per tal d’enriquir-se entre tot l’alumnat i treure profit d’elles. A la vegada aquest agrupament es caracteritza per fomentar la igualtat d’oportunitats en l’aprenentatge dels alumnes. En canvi, al futbol base predominen els agrupaments homogenis, distribuint als jugadors segons el seu nivell en diferents equips. A la recerca es fa una comparació entre l’opinió de diferents membres involucrats en el món del futbol base de dues entitats esportives, un club de futbol, on es fan els grups de forma homogènia, i una escola de futbol, on es fan els agrupaments de forma heterogènia. Els resultats mostren que realitzant agrupaments homogenis no s’assegura que tots els jugadors tinguin les mateixes oportunitats d’aprenentatge i que el nivell competencial dels jugadors en edat de formació pot ser un element que fomenti desigualtats en el seu procés d’aprenentatge esportiu.

Non-resorbable glass fibre-reinforced composite with porous surface as bone substitute material: Experimental studies in vitro and in vivo focused on bone-implant interface

The development of load-bearing osseous implant with desired mechanical and surface properties in order to promote incorporation with bone and to eliminate risk of bone resorption and implant failure is a very challenging task. Bone formation and resoption processes depend on the mechanical environment. Certain stress/strain conditions are required to promote new bone growth and to prevent bone mass loss. Conventional metallic implants with high stiffness carry most of the load and the surrounding bone becomes virtually unloaded and inactive. Fibre-reinforced composites offer an interesting alternative to metallic implants, because their mechanical properties can be tailored to be equal to those of bone, by the careful selection of matrix polymer, type of fibres, fibre volume fraction, orientation and length. Successful load transfer at bone-implant interface requires proper fixation between the bone and implant. One promising method to promote fixation is to prepare implants with porous surface. Bone ingrowth into porous surface structure stabilises the system and improves clinical success of the implant. The experimental part of this work was focused on polymethyl methacrylate (PMMA) -based composites with dense load-bearing core and porous surface. Three-dimensionally randomly orientated chopped glass fibres were used to reinforce the composite. A method to fabricate those composites was developed by a solvent treatment technique and some characterisations concerning the functionality of the surface structure were made in vitro and in vivo. Scanning electron microscope observations revealed that the pore size and interconnective porous architecture of the surface layer of the fibre-reinforced composite (FRC) could be optimal for bone ingrowth. Microhardness measurements showed that the solvent treatment did not have an effect on the mechanical properties of the load-bearing core. A push-out test, using dental stone as a bone model material, revealed that short glass fibre-reinforced porous surface layer is strong enough to carry load. Unreacted monomers can cause the chemical necrosis of the tissue, but the levels of leachable resisidual monomers were considerably lower than those found in chemically cured fibre-reinforced dentures and in modified acrylic bone cements. Animal experiments proved that surface porous FRC implant can enhance fixation between bone and FRC. New bone ingrowth into the pores was detected and strong interlocking between bone and the implant was achieved.

Uncertainties of the 137Cs technique for validation of soil redistribution modelling in a semiarid meso-scale watershed

Scarcity of long-term series of sediment-related variables has led watershed managers to apply mathematical models to simulate sediment fluxes. Due to the high efforts for installation and maintenance of sedimentological gauges, tracers have been pointed out as an alternative to validate soil redistribution modelling. In this study, the 137Cs technique was used to assess the WASA-SED model performance at the Benguê watershed (933 km²), in the Brazilian semiarid. Qualitatively, good agreement was found among the 137Cs technique and the WASA-SED model results. Nonetheless, quantitatively great differences, up to two orders of magnitude, were found between the two methods. Among the uncertainties inherent to the 137Cs technique, definition of the reference inventory seems to be a major source of imprecision. In addition, estimations of water and sediment fluxes with mathematical models usually also present high uncertainty, contributing to the quantitative differences of the soil redistribution estimates with the two methods.

Integration of existing military capability models into the Comprehensive Capability Meta-model

Abstract—This paper discusses existing military capability models and proposes a comprehensive capability meta-model (CCMM) which unites the existing capability models into an integrated and hierarchical whole. The Zachman Framework for Enterprise Architecture is used as a structure for the CCMM. The CCMM takes into account the abstraction level, the primary area of application, stakeholders, intrinsic process, and life cycle considerations of each existing capability model, and shows how the models relate to each other. The validity of the CCMM was verified through a survey of subject matter experts. The results suggest that the CCMM is of practical value to various capability stakeholders in many ways, such as helping to improve communication between the different capability communities.

The holistic military capability life cycle model

Abstract - This paper reviews existing military capability models and the capability life cycle. It proposes a holistic capability life-cycle model (HCLCM) that combines capability systems with related capability models. ISO 15288 standard is used as a framework to construct the HCLCM. The HCLCM also shows how capability models and systems relate to each other throughout the capability life cycle. The main contribution of this paper is conceptual in nature. The model complements the existing, but still evolving, understanding of the military capability life cycle in a holistic and systemic way. The model also increases understanding and facilitates communication among various military capability stakeholders.

The Role of Universities in the Triple Helix model of innovation management within the biotechnology industry, Case example: Turku Science Park Network

Biotechnology has been recognized as the key strategic technology for industrial growth. The industry is heavily dependent on basic research. Finland continues to rank in the top 10 of Europe's most innovative countries in terms of tax-policy, education system, infrastructure and the number of patents issued. Regardless of the excellent statistical results, the output of this innovativeness is below acceptable. Research on the issues hindering the output creation has already been done and the identifiable weaknesses in the Finland's National Innovation system are the non-existent growth of entrepreneurship and the missing internationalization. Finland is proven to have all the enablers of the innovation policy tools, but is lacking the incentives and rewards to push the enablers, such as knowledge and human capital, forward. Science Parks are the biggest operator in research institutes in the Finnish Science and Technology system. They exist with the purpose of speeding up the commercialization process of biotechnology innovations which usually include technological uncertainty, technical inexperience, business inexperience and high technology cost. Innovation management only internally is a rather historic approach, current trend drives towards open innovation model with strong triple helix linkages. The evident problems in the innovation management within the biotechnology industry are examined through a case study approach including analysis of the semi-structured interviews which included biotechnology and business expertise from Turku School of Economics. The results from the interviews supported the theoretical implications as well as conclusions derived from the pilot survey, which focused on the companies inside Turku Science Park network. One major issue that the Finland's National innovation system is struggling with is the fact that it is technology driven, not business pulled. Another problem is the university evaluation scale which focuses more on number of graduates and short-term factors, when it should put more emphasis on the cooperation success in the long-term, such as the triple helix connections with interaction and knowledge distribution. The results of this thesis indicated that there is indeed requirement for some structural changes in the Finland's National innovation system and innovation policy in order to generate successful biotechnology companies and innovation output. There is lack of joint output and scales of success, lack of people with experience, lack of language skills, lack of business knowledge and lack of growth companies.

Long-term nutrient load management and lake restoration: Case of Säkylän Pyhäjärvi (SW Finland)

Eutrophication caused by anthropogenic nutrient pollution has become one of the most severe threats to water bodies. Nutrients enter water bodies from atmospheric precipitation, industrial and domestic wastewaters and surface runoff from agricultural and forest areas. As point pollution has been significantly reduced in developed countries in recent decades, agricultural non-point sources have been increasingly identified as the largest source of nutrient loading in water bodies. In this study, Lake Säkylän Pyhäjärvi and its catchment are studied as an example of a long-term, voluntary-based, co-operative model of lake and catchment management. Lake Pyhäjärvi is located in the centre of an intensive agricultural area in southwestern Finland. More than 20 professional fishermen operate in the lake area, and the lake is used as a drinking water source and for various recreational activities. Lake Pyhäjärvi is a good example of a large and shallow lake that suffers from eutrophication and is subject to measures to improve this undesired state under changing conditions. Climate change is one of the most important challenges faced by Lake Pyhäjärvi and other water bodies. The results show that climatic variation affects the amounts of runoff and nutrient loading and their timing during the year. The findings from the study area concerning warm winters and their influences on nutrient loading are in accordance with the IPCC scenarios of future climate change. In addition to nutrient reduction measures, the restoration of food chains (biomanipulation) is a key method in water quality management. The food-web structure in Lake Pyhäjärvi has, however, become disturbed due to mild winters, short ice cover and low fish catch. Ice cover that enables winter seining is extremely important to the water quality and ecosystem of Lake Pyhäjärvi, as the vendace stock is one of the key factors affecting the food web and the state of the lake. New methods for the reduction of nutrient loading and the treatment of runoff waters from agriculture, such as sand filters, were tested in field conditions. The results confirm that the filter technique is an applicable method for nutrient reduction, but further development is needed. The ability of sand filters to absorb nutrients can be improved with nutrient binding compounds, such as lime. Long-term hydrological, chemical and biological research and monitoring data on Lake Pyhäjärvi and its catchment provide a basis for water protection measures and improve our understanding of the complicated physical, chemical and biological interactions between the terrestrial and aquatic realms. In addition to measurements carried out in field conditions, Lake Pyhäjärvi and its catchment were studied using various modelling methods. In the calibration and validation of models, long-term and wide-ranging time series data proved to be valuable. Collaboration between researchers, modellers and local water managers further improves the reliability and usefulness of models. Lake Pyhäjärvi and its catchment can also be regarded as a good research laboratory from the point of view of the Baltic Sea. The main problem in both of them is eutrophication caused by excess nutrients, and nutrient loading has to be reduced – especially from agriculture. Mitigation measures are also similar in both cases.

Is pancreas development abnormal in the non-obese diabetic mouse, a spontaneous model of type I diabetes?

Despite extensive genetic and immunological research, the complex etiology and pathogenesis of type I diabetes remains unresolved. During the last few years, our attention has been focused on factors such as abnormalities of islet function and/or microenvironment, that could interact with immune partners in the spontaneous model of the disease, the non-obese diabetic (NOD) mouse. Intriguingly, the first anomalies that we noted in NOD mice, compared to control strains, are already present at birth and consist of 1) higher numbers of paradoxically hyperactive ß cells, assessed by in situ preproinsulin II expression; 2) high percentages of immature islets, representing islet neogenesis related to neonatal ß-cell hyperactivity and suggestive of in utero ß-cell stimulation; 3) elevated levels of some types of antigen-presenting cells and FasL+ cells, and 4) abnormalities of extracellular matrix (ECM) protein expression. However, the colocalization in all control mouse strains studied of fibroblast-like cells (anti-TR-7 labeling), some ECM proteins (particularly, fibronectin and collagen I), antigen-presenting cells and a few FasL+ cells at the periphery of islets undergoing neogenesis suggests that remodeling phenomena that normally take place during postnatal pancreas development could be disturbed in NOD mice. These data show that from birth onwards there is an intricate relationship between endocrine and immune events in the NOD mouse. They also suggest that tissue-specific autoimmune reactions could arise from developmental phenomena taking place during fetal life in which ECM-immune cell interaction(s) may play a key role.

Mechanisms underlying gas exchange alterations in an experimental model of pulmonary embolism

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 ± 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 ± 8.64 to 39.14 ± 6.77 mmHg) and alveolar air (from 92.97 ± 2.14 to 63.91 ± 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 ± 42.01 to 84.34 ± 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 ± 0.34 to 0.33 ± 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 ± 1.71 to 60.76 ± 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 ± 1.22 to 23.15 ± 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 ± 1.36 to 37.61 ± 12.79 mmHg), as also did the calculated alveolar (from 56.38 ± 22.47 to 178.09 ± 37.46 mL) and physiological (from 0.37 ± 0.05 to 0.75 ± 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.

Post-transaction brand and model line-up integration in the automotive industry: Case studies of European companies as target of acquisitions by Chinese and Indian multinational corporations

Corporations practice company acquisitions in order to create shareholder’s value. During the last few decades, the companies in emerging markets have become active in the acquisition business. During the last decade, large and significant acquisitions have occurred especially in automotive industry. While domestic markets have become too competitive and companies are lacking required capabilities, they seek possibilities to expand into Western markets by attaining valuable assets through acquisitions of developed country corporations. This study discusses the issues and characteristics of these acquisitions through case studies. The purpose of this study was to identify the acquisition motives and strategies for post-transaction brand and product integration as well as analyze the effect of the motives to the integration strategy. The cases chosen for the research were Chinese Geely acquiring Swedish Volvo in 2010 and Indian Tata Motors buying British Jaguar Land Rover in 2008. The main topics were chosen according to their significance for companies in automotive industry as well as those are most visible parts for consumers. The study is based on qualitative case study methods, analyzing secondary data from academic papers and news articles as well as companies’ own announcements e.g. stock exchange and press releases. The study finds that the companies in the cases mainly possessed asset-seeking and market-seeking motives. In addition, the findings refer to rather minimal post-acquisition brand and product integration strategies. Mainly the parent companies left the target company autonomous to make their own business strategies and decisions. The most noticeable integrations were in the product development and production processes. Through restructuring the product architectures, the companies were able to share components and technology between product families and brands, which results in cutting down costs and in increase of profitability and efficiency. In the Geely- Volvo case, the strategy focused more on component sharing and product development know-how, whereas in Tata Motors-Jaguar Land Rover case, the main actions were to cut down costs through component sharing and combine production and distribution networks especially in Asian markets. However, it was evident that in both cases the integration and technology sharing were executed cautiously to prevent on harming the valuable image of the luxury brand. This study has concluded that the asset-seeking motives have significant influence on the posttransaction brand and model line-up integration strategies. By taking a cautious approach in acquiring assets, such as luxury brand, the companies in the cases have implemented a successful post-acquisition strategy and managed to create value for the shareholders at least in short-term. Yritykset harjoittavat yritysostoja luodakseen osakkeenomistajille lisäarvoa. Viimeisten muutamien vuosikymmenien aikana yritykset kehittyvissä maissa ovat myös aktivoituneet yritysostoissa. Viimeisen vuosikymmenen aikana erityisesti autoteollisuudessa on esiintynyt suuria ja merkittäviä yritysostoja. Koska kilpailu kotimaan markkinoilla on kiristynyt ja yritykset ovat vailla vaadittavia valmiuksia, ne etsivät mahdollisuuksiaan laajentaa länsimaisiin markkinoihin hankkimalla arvokkaita etuja kehittyneiden maiden yrityksistä yritysostojen avulla. Tämä tutkimus pohtii näiden yritysostojen olennaisia kysymyksiä ja ominaisuuksia casetutkimuksien kautta. Tutkimuksen tarkoitus oli tunnistaa sekä yritysostojen motiiveja ja brändi- ja mallisto-integraation strategioita että analysoida kyseisten motiivien vaikutusta integraatiostrategiaan. Tapaus-tutkimuksiksi valittiin kiinalaisen Geelyn yritysosto ruotsalaisesta Volvosta vuonna 2010 ja intialaisen Tata Motorsin yritysosto englantilaisesta Jaguar Land Roverista vuonna 2008. Tutkimus on kvalitatiivinen case-tutkimus ja siinä analysoidaan toissijaista tietoa sekä akateemisten ja uutisartikkeleiden että yritysten omien ilmoitusten, kuten pörssi- ja lehdistötiedotteiden, kautta. Tutkimuksen tulokset osoittavat, että tutkittujen yritysten toiminnat perustuivat motiiveihin, joita ajoivat etujen and uusien markkinoiden tarve. Sen lisäksi tutkimustulokset osoittivat, että yritysoston jälkeinen brändi- ja mallisto-integraatio pidettiin minimaalisena. Pääasiallisesti kohdeyrityksille jätettiin autonomia tehdä omat liikkeenjohdolliset päätökset yritysstrategioihin liittyen. Huomattavimmat integraatiot koskivat tuotekehityksellisiä ja tuotannollisia prosesseja. Kehittämällä uudelleen tuotearkkitehtuureja, yritykset pystyivät jakamaan komponentteja ja teknologiaa tuoteperheiden ja brändien välillä. Tämä mahdollisti kustannusleikkauksia sekä kannattavuuden ja tehokkuuden parantamista. Geely-Volvo –tapauksessa integraatiostrategia keskittyi komponenttien jakamiseen yhteisten tuotearkkitehtuurien avulla ja tuotekehityksen ammattitaitoon, kun taas Tata Motors-JLR –tapauksessa päätoiminnat olivat kustannuksien leikkaus sekä tuotannon ja jakeluverkoston yhdistäminen erityisesti Aasian maissa. Yhteistä yrityskaupoissa oli, että brändi- ja mallisto-integraatio sekä teknologian jakaminen suoritettiin varoen ehkäistäkseen arvokkaiden luksus-brändien tuotekuvan vahingoittamista. Tutkimuksen lopputulokset osoittavat, että yrityskaupan motiiveilla on huomattava vaikutus brändija mallisto-integraation strategiaan. Toteuttamalla varovaista lähestymistapaa luksus-brändin hankinnassa ja integraatiossa, yritykset ovat onnistuneet luomaan lisäarvoa osakkeenomistajille vähintään lyhyellä aikavälillä.

Item-level life-cycle model for maintenance network – from cost to additional value

The importance of industrial maintenance has been emphasized during the last decades; it is no longer a mere cost item, but one of the mainstays of business. Market conditions have worsened lately, investments in production assets have decreased, and at the same time competition has changed from taking place between companies to competition between networks. Companies have focused on their core functions and outsourced support services, like maintenance, above all to decrease costs. This new phenomenon has led to increasing formation of business networks. As a result, a growing need for new kinds of tools for managing these networks effectively has arisen. Maintenance costs are usually a notable part of the life-cycle costs of an item, and it is important to be able to plan the future maintenance operations for the strategic period of the company or for the whole life-cycle period of the item. This thesis introduces an itemlevel life-cycle model (LCM) for industrial maintenance networks. The term item is used as a common definition for a part, a component, a piece of equipment etc. The constructed LCM is a working tool for a maintenance network (consisting of customer companies that buy maintenance services and various supplier companies). Each network member is able to input their own cost and profit data related to the maintenance services of one item. As a result, the model calculates the net present values of maintenance costs and profits and presents them from the points of view of all the network members. The thesis indicates that previous LCMs for calculating maintenance costs have often been very case-specific, suitable only for the item in question, and they have also been constructed for the needs of a single company, without the network perspective. The developed LCM is a proper tool for the decision making of maintenance services in the network environment; it enables analysing the past and making scenarios for the future, and offers choices between alternative maintenance operations. The LCM is also suitable for small companies in building active networks to offer outsourcing services for large companies. The research introduces also a five-step constructing process for designing a life-cycle costing model in the network environment. This five-step designing process defines model components and structure throughout the iteration and exploitation of user feedback. The same method can be followed to develop other models. The thesis contributes to the literature of value and value elements of maintenance services. It examines the value of maintenance services from the perspective of different maintenance network members and presents established value element lists for the customer and the service provider. These value element lists enable making value visible in the maintenance operations of a networked business. The LCM added with value thinking promotes the notion of maintenance from a “cost maker” towards a “value creator”.

Aspergillus flavus infections in Galleria mellonella : a pathogen-host model system for the study of emerging diseases

To study emerging diseases, I employed a model pathogen-host system involving infections of insect larvae with the opportunistic fungus Aspergillus flavus, providing insight into three mechanisms ofpathogen evolution namely de novo mutation, genome decay, and virulence factoracquisition In Chapter 2 as a foundational experiment, A. flavus was serially propagated through insects to study the evolution of an opportunistic pathogen during repeated exposure to a single host. While A. flavus displayed de novo phenotypic alterations, namely decreased saprobic capacity, analysis of genotypic variation in Chapter 3 signified a host-imposed bottleneck on the pathogen population, emphasizing the host's role in shaping pathogen population structure. Described in Chapter 4, the serial passage scheme enabled the isolation of an A. flavus cysteine/methionine auxotroph with characteristics reminiscent of an obligate insect pathogen, suggesting that lost biosynthetic capacity may restrict host range based on nutrient availability and provide selection pressure for further evolution. As outlined in Chapter 6, cysteine/methionine auxotrophy had the pleiotrophic effect of increasing virulence factor production, affording the slow-growing auxotroph with a modified pathogenic strategy such that virulence was not reduced. Moreover in Chapter 7, transformation with a virulence factor from a facultative insect pathogen failed to increase virulence, demonstrating the necessity of an appropriate genetic background for virulence factor acquisition to instigate pathogen evolution.

“Weathering a Hidden Storm”: An Application of Andersen’s Behavioral Model of Health, and Health Services Use for Those with Diagnosable Anxiety Disorder

Abstract: Research has primarily focused on depression and mood disorders, but little research has been devoted to an examination of mental health services use amongst those with diagnosable anxiety disorder (Wittchen et al., 2002; Bergeron et al., 2005). This study examined the possible predicting factors for mental health services utilization amongst those with identifiable anxiety disorder in the Canadian population. The methods used for this study was the application of Andersen’s Behavioral Model of Health Services Use, where predisposing, need and enabling characteristics were regressed on the dependent variable of mental health services use. This study used the Canadian Community Health Survey (cycle 1.2: Mental Health and Well-Being) in a secondary data analysis. Several multiple logistics models predicted the likelihood to seek and use mental health services. Predisposing characteristics of gender and age, Enabling characteristics of education and geographical location, and those with co-occurring mood disorders were at the greatest increased likelihood to seek and use mental health services.