Thèses sur le sujet « Impayé »

L'objectif de ces travaux de thèse est de proposer des approches de modélisation et d'expérimentation de l'impact de structures déformables et indéformables sur différents milieux. Différents modèles analytiques et des simulations numériques sont développés en comparaison aux résultats expérimentaux. Une première partie se consacre à la caractérisation de la similitude entre la réponse à l'impact à l'eau d'un solide et la réponse d'un solide impactant une structure déformable. Des simulations éléments finis (EF) et SPH sont réalisées pour l'impact à l'eau d'un tube cylindrique (sans rupture). Un modèle analytique d'impact à l'eau est proposé pour prédire l'évolution de l'effort (pic, durée). L'analyse des résultats permet de dimensionner un programmateur d'impact solide reproduisant le pic d'effort. Des simulations EF de l'impact sur un tube cylindrique, à géométrie adapté, dans la direction longitudinale, sont réalisées et comparées à quelques expériences tests. Le «flambage dynamique» (dû au comportement inélastique du matériau et aux ondes de déformations) des tubes est alors observé. Une seconde partie traite du cas de la perforation sous impact d'une tôle mince à faibles vitesses d'impact (< 10 m/s, vitesse de déformation < 1000 s-1). Des essais sur puits de chute instrumenté (force, déplacement, déformée de tôle, avancée de fissure) sont analysés. Des simulations EF en éléments coques avec un critère de rupture ductile par endommagement sont réalisées. Les paramètres de rupture dynamique sont identifiés par méthode inverse à l'aide d'essais de résilience Charpy sur l'alliage d'aluminium de désignation 2024 T3. Une analyse des pics de force lors de l'impact permet une meilleure compréhension des mécanismes de perforation. En parallèle, un nouveau modèle analytique, basé sur les énergies impliquées lors de l'impact, est proposé et comparé aux simulations EF. L'étude numérique de la perforation est étendue aux grandes vitesses d'impact et de déformation (100 - 1000 m/s, vitesse de déformation <100 000 s-1) pour identifier les transitions des différents mécanismes de perforation connus (pétalisation, fragmentation des pétales, fragmentation complète)
The objective of this work is to propose approaches to model and to assess experimentally the structural impact on different media. A variety of analytic models and numerical simulations are developed comparing to experimental results. The first part of this work presents a discussion on the similitude between a water impact and an impact on a deformable solid structure. Water impact simulations of a deformable cylinder (without rupture) are performed by finite elements (FE, Coupled Eulerian Lagrangian) and SPH analysis. An analytical model of water impact is proposed for the prediction of peak force evolution. The analysis of results permits to design an impact programmer reproducing this peak force. FE longitudinal impact simulations on cylindrical tubes, with an adapted geometry, are performed and compared with some experiments. The “dynamic buckling” of tubes under impact (due to the material inelastic behavior and to strain waves) is observed. The second part deals with the low velocity perforation (< 10 m/s, strain rate < 1000 s-1) of thin plates. Some experiments on an instrumented drop test (force, displacement, plate shape, crack propagation) are analyzed. Shell FE simulations, with a damage rupture criteria implemented are performed. Parameters are identified by inverse method with the help of Charpy tests made on 2024 T3 aluminum alloy. An analysis of the peak force, during impact, leads to a good understanding of the perforation mechanism. In parallel, a new analytical model, based on an energetic approach of the perforation, is proposed and compared with FE simulations. The numerical perforation study is extended to high velocities and high strain rates (100 - 1000m/s, strain rate < 100 000 s-1) in order to identify different well-known transitions of perforation (Petalisation, petals' fragmentation, total plate's fragmentation)

Adapting sectors to new conditions under climate change requires an understanding of regional vulnerabilities. Conceptually, vulnerability is defined as a function of sensitivity and exposure, which determine climate impacts, and adaptive capacity of a system. Vulnerability assessments for quantifying these components have become a key tool within the climate change field. However, there is a disagreement on how to make the concept operational in studies from a scientific perspective. This conflict leads to many still unsolved challenges, especially regarding the quantification and aggregation of the components and their suitable level of complexity. This thesis therefore aims at advancing the scientific foundation of such studies by translating the concept of vulnerability into a systematic assessment structure. This includes all components and implies that for each considered impact (e.g. flash floods) a clear sensitive entity is defined (e.g. settlements) and related to a direction of change for a specific climatic stimulus (e.g. increasing impact due to increasing days with heavy precipitation). Regarding the challenging aggregation procedure, two alternative methods allowing a cross-sectoral overview are introduced and their advantages and disadvantages discussed. This assessment structure is subsequently exemplified for municipalities of the German state North Rhine-Westphalia via an indicator-based deductive approach using information from literature. It can be transferred also to other regions. As for many relevant sectors, suitable indicators to express the vulnerability components are lacking, new quantification methods are developed and applied in this thesis, for example for the forestry and health sector. A lack of empirical data on relevant thresholds is evident, for example which climatic changes would cause significant impacts. Consequently, the multi-sectoral study could only provide relative measures for each municipality, in relation to the region. To fill this gap, an exemplary sectoral study was carried out on windthrow impacts in forests to provide an absolute quantification of the present and future impact. This is achieved by formulating an empirical relation between the forest characteristics and damage based on data from a past storm event. The resulting measure indicating the sensitivity is then combined with wind conditions. Multi-sectoral vulnerability assessments require considerable resources, which often hinders the implementation. Thus, in a next step, the potential for reducing the complexity is explored. To predict forest fire occurrence, numerous meteorological indices are available, spanning over a range of complexity. Comparing their performance, the single variable relative humidity outperforms complex indicators for most German states in explaining the monthly fire pattern. This is the case albeit it is itself an input factor in most indices. Thus, this meteorological factor alone is well suited to evaluate forest fire danger in many Germany regions and allows a resource-efficient assessment. Similarly, the complexity of methods is assessed regarding the application of the ecohydrological model SWIM to the German region of Brandenburg. The inter-annual soil moisture levels simulated by this model can only poorly be represented by simpler statistical approach using the same input data. However, on a decadal time horizon, the statistical approach shows a good performance and a strong dominance of the soil characteristic field capacity. This points to a possibility to reduce the input factors for predicting long-term averages, but the results are restricted by a lack of empirical data on soil water for validation. The presented assessments of vulnerability and its components have shown that they are still a challenging scientific undertaking. Following the applied terminology, many problems arise when implementing it for regional studies. Advances in addressing shortcomings of previous studies have been made by constructing a new systematic structure for characterizing and aggregating vulnerability components. For this, multiple approaches were presented, but they have specific advantages and disadvantages, which should also be carefully considered in future studies. There is a potential to simplify some methods, but more systematic assessments on this are needed. Overall, this thesis strengthened the use of vulnerability assessments as a tool to support adaptation by enhancing their scientific basis.
Die Anpassung von Sektoren an veränderte klimatische Bedingungen erfordert ein Verständnis von regionalen Vulnerabilitäten. Vulnerabilität ist als Funktion von Sensitivität und Exposition, welche potentielle Auswirkungen des Klimawandels darstellen, und der Anpassungsfähigkeit von Systemen definiert. Vulnerabilitätsstudien, die diese Komponenten quantifizieren, sind zu einem wichtigen Werkzeug in der Klimawissenschaft geworden. Allerdings besteht von der wissenschaftlichen Perspektive aus gesehen Uneinigkeit darüber, wie diese Definition in Studien umgesetzt werden soll. Ausdiesem Konflikt ergeben sich viele Herausforderungen, vor allem bezüglich der Quantifizierung und Aggregierung der einzelnen Komponenten und deren angemessenen Komplexitätsniveaus. Die vorliegende Dissertation hat daher zum Ziel die Anwendbarkeit des Vulnerabilitätskonzepts voranzubringen, indem es in eine systematische Struktur übersetzt wird. Dies beinhaltet alle Komponenten und schlägt für jede Klimaauswirkung (z.B. Sturzfluten) eine Beschreibung des vulnerablen Systems vor (z.B. Siedlungen), welches direkt mit einer bestimmten Richtung eines relevanten klimatischen Stimulus in Verbindung gebracht wird (z.B. stärkere Auswirkungen bei Zunahme der Starkregentage). Bezüglich der herausfordernden Prozedur der Aggregierung werden zwei alternative Methoden, die einen sektorübergreifenden Überblick ermöglichen, vorgestellt und deren Vor- und Nachteile diskutiert. Anschließend wird die entwickelte Struktur einer Vulnerabilitätsstudie mittels eines indikatorbasierten und deduktiven Ansatzes beispielhaft für Gemeinden in Nordrhein-Westfalen in Deutschland angewandt. Eine Übertragbarkeit auf andere Regionen ist dennoch möglich. Die Quantifizierung für die Gemeinden stützt sich dabei auf Informationen aus der Literatur. Da für viele Sektoren keine geeigneten Indikatoren vorhanden waren, werden in dieser Arbeit neue Indikatoren entwickelt und angewandt, beispielsweise für den Forst- oder Gesundheitssektor. Allerdings stellen fehlende empirische Daten bezüglich relevanter Schwellenwerte eine Lücke dar, beispielsweise welche Stärke von Klimaänderungen eine signifikante Auswirkung hervorruft. Dies führt dazu, dass die Studie nur relative Aussagen zum Grad der Vulnerabilität jeder Gemeinde im Vergleich zum Rest des Bundeslandes machen kann. Um diese Lücke zu füllen, wird für den Forstsektor beispielhaft die heutige und zukünftige Sturmwurfgefahr von Wäldern berechnet. Zu diesem Zweck werden die Eigenschaften der Wälder mit empirischen Schadensdaten eines vergangenen Sturmereignisses in Verbindung gebracht. Der sich daraus ergebende Sensitivitätswert wird anschließend mit den Windverhältnissen verknüpft. Sektorübergreifende Vulnerabilitätsstudien erfordern beträchtliche Ressourcen, was oft deren Anwendbarkeit erschwert. In einem nächsten Schritt wird daher das Potential einer Vereinfachung der Komplexität anhand zweier sektoraler Beispiele untersucht. Um das Auftreten von Waldbränden vorherzusagen, stehen zahlreiche meteorologische Indices zur Verfügung, welche eine Spannbreite unterschiedlicher Komplexitäten aufweisen. Bezüglich der Anzahl monatlicher Waldbrände weist die relative Luftfeuchtigkeit für die meisten deutschen Bundesländer eine bessere Vorhersagekraft als komplexere Indices auf. Dies ist er Fall, obgleich sie selbst als Eingangsvariable für die komplexeren Indices verwendet wird. Mit Hilfe dieses einzelnen meteorologischen Faktors kann also die Waldbrandgefahr in deutschen Region ausreichend genau ausgedrückt werden, was die Ressourceneffizienz von Studien erhöht. Die Methodenkomplexität wird auf ähnliche Weise hinsichtlich der Anwendung des ökohydrologischen Modells SWIM für die Region Brandenburg untersucht. Die interannuellen Bodenwasserwerte, welche durch dieses Modell simuliert werden, können nur unzureichend durch ein einfacheres statistisches Modell, welches auf denselben Eingangsdaten aufbaut, abgebildet werden. Innerhalb eines Zeithorizonts von Jahrzehnten, kann der statistische Ansatz jedoch das Bodenwasser zufriedenstellend abbilden und zeigt eine Dominanz der Bodeneigenschaft Feldkapazität. Dies deutet darauf hin, dass die Komplexität im Hinblick auf die Anzahl der Eingangsvariablen für langfristige Berechnungen reduziert werden kann. Allerdings sind die Aussagen durch fehlende beobachtete Bodenwasserwerte zur Validierung beschränkt. Die vorliegenden Studien zur Vulnerabilität und ihren Komponenten haben gezeigt, dass eine Anwendung noch immer wissenschaftlich herausfordernd ist. Folgt man der hier verwendeten Vulnerabilitätsdefinition, treten zahlreiche Probleme bei der Implementierung in regionalen Studien auf. Mit dieser Dissertation wurden Fortschritte bezüglich der aufgezeigten Lücken bisheriger Studien erzielt, indem eine systematische Struktur für die Beschreibung und Aggregierung von Vulnerabilitätskomponenten erarbeitet wurde. Hierfür wurden mehrere Ansätze diskutiert, die jedoch Vor- und Nachteile besitzen. Diese sollten vor der Anwendung von zukünftigen Studien daher ebenfalls sorgfältig abgewogen werden. Darüber hinaus hat sich gezeigt, dass ein Potential besteht einige Ansätze zu vereinfachen, jedoch sind hierfür weitere Untersuchungen nötig. Insgesamt konnte die Dissertation die Anwendung von Vulnerabilitätsstudien als Werkzeug zur Unterstützung von Anpassungsmaßnahmen stärken.

Thesis (MBA)--Stellenbosch University, 2012.
The mining industry has had a significant role to play in addressing socio-economic development (SED) issues, such as the high levels of poverty, illiteracy and unemployment. For South Africa to be able to eradicate poverty and illiteracy, a collaborative partnership between the government, the mining industry and local mining communities is critical. The Minister of Mineral Resources, Shabangu (2012), has encouraged the mining industry to ensure that corporate social responsibility (CSR) investments make a significant impact on the communities in which the mining companies operate and to stop making CSR a mere exercise in ticking off a scorecard. The Mining Charter states that the mining industry must promote employment and advance social and economic welfare of mining community and the major sending areas. The aim of the current study was to evaluate the impact of the Impala Platinum (Implats) CSR programme, Marula Chrome Project, on the Marula community. The challenges that Implats and the Marula community experienced during the implementation of the project were explored. If the project was to be successful, the key success factors had to be identified. The Marula Chrome Project was commissioned in 2010. The Project created 69 job opportunities during its construction period, and 35 permanent jobs after its completion. A number of SED issues were addressed by the project through skills development and training. The community leaders attended an intensive business principles course, covering the basic principles of mining, business skills and corporate governance. The employees of the project also were empowered with relevant operational and management skills. The project had, by the time of the report, paid out dividends to the value of R20 million to the communities. Two community halls had been built with the amount of R4 million. The dividends were distributed to the six Marula communities, who spent the money obtained in this way for addressing such SED problems as infrastructure, education and enterprise development. This project is one of the few examples of CSR initiatives in South Africa. The researcher hopes that other local mining communities can learn what made this project successful. The findings of the projects show that the community and Implats have managed the challenges faced during the project and have focused on the important issues. Collaborative partnership and leadership is one of the key success factors highlighted. Kinnear and Miles (2009) agree that partnerships and local coordination between the mining industry, the government and the community are vital. Positive outcomes can be achieved by means of community‐driven initiatives. According to CSR scholars such as Muthuri (2012), CSR is a potent force for social change and poverty alleviation. The lack of CSR impact evaluation tools required addressing by Implats and the mining industry. The mining industry and the Department of Mineral Resources should work together on developing an evaluation tool by means of which to measure CSR initiatives. Doing so would assist the mining industry CSR investments to add value and to contribute to the eradication of poverty and illiteracy in the local communities.

This master thesis focuses on modelling and simulation of impact tests of composite panels. Simulations and analysis were made by using Finite Element Method in software MSC Patran and Dytran. The first part of the thesis deals with describing the properties of composite panels during impact testing and other cases of impacts on composite structures. Next part deals with the used models and results from Dytran. These results are compared with experimental data from real low-velocity impact tests. Part of the thesis is devoted to impact on panels with the stacking sequences which is supposed to be used for design of air duct for airplane Aero L-39NG.

Social Impact Assessment (SIA) identifies the intended and unintended impacts that proposed projects or developments are likely to have on a community or individuals and suggest mitigation measures to prevent these impacts and enhance the positive impacts. The main aim of this dissertation is to explore the significance and the status of SIA in a South African context. EIA is currently in its third era of mandatory practice and with an increasing number of SIAs, it is essential that the practice of SIA should be investigated. The aim of this dissertation was firstly reached by exploring the perspectives of SIA practitioners in South Africa through a questionnaire. The practitioners’ perspectives showed that despite distinct weaknesses in the practice of SIA, i.e. the lack of a fixed set of guidelines and a shortage of SIA skill in the practitioner community, SIA practice has improved since 1997 with the promulgation of ECA, although there is still room for improvement. Secondly a quality review was conducted on a sample of SIARs in South Africa using an adapted review package. The results revealed relatively weak report quality compared to EIA report quality, but with an improvement, in report quality since 1997. The quality review findings appear to confirm the perspectives of the practitioners regarding the state of SIA practice in South Africa. Despite the weaknesses in the SIA process, it appears that the SIA practitioner community is driven by best practice considerations, and that SIA practice is in line with international trends. It appears therefore that despite the observed weaknesses, SIA practice in South Africa is relatively healthy. It is recommended that instead of seeking to strengthen SIA practice by means of regulation and guidelines, SIA practitioners should rather ensure that SIA delivers what it is intended to deliver by ongoing pursuance of best practice, and by improved training and skills development.
Thesis (MSc (Geography and Environmental Studies))--North-West University, Potchefstroom Campus, 2013

Rockfall represents a significant hazard not only in mountainous areas, but also alongside coastal routes, major transport infrastructures and quarry faces. One aspect of the rockfall phenomenon that still requires further investigations is the fragmentation of falling blocks upon impact. The changes in size, shape and energy of the falling blocks upon fragmentation and the variation in trajectory of the fragments can seriously affect the optimization design of the rockfall mitigation measures. The fragmentation of boulders during a rockfall event can lead to significant changes in the global run-out distances and the maximum kinetic energy to be accounted in the protection systems design. This thesis presents an experimental program conducted to investigate the fragmentation phenomenon under controlled conditions to provide some useful insights in terms of block survival probability upon dynamic impact, fragments distribution, post impact velocity and energy dissipation upon impact. The result of this thesis will focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved, reproducing many experimental observations of fragment shapes and impact energy, and significantly improve the understanding of the fragmentation process for impact fracture. Spheres shapes were chosen because of their simple body geometry and consequent impact and stress field symmetry. So, the description of materials, sample preparation and tests program conducted for 175 mortar spheres of different diameter built for the current research will be presented to evaluate the survival probability of homogeneous artificial rocks with a known compressive strength dropped from a certain height and to observe the fragmentation process upon impact with a known impacting energy.

Lorsque nous parlons de relations internationales, nous parlons généralement de diplomatie et d'investissement, Le sport peut être utilisé comme outil pour améliorer la diplomatie entre les pays, ainsi que pour développer les intérêts économiques et sociaux. De plus, le sport occupe une place importante dans le repositionnement de l'image d'une nation, tout en améliorant le processus d'intégration des jeunes générations dans le monde. L'un des principaux intérêts, du point de vue du gouvernement, est de créer un lien affectif positif avec la nation hôte de l’évènement sportif. Ce qu'on appelle le soft power. Le but de ce travail est d'explorer certaines des façons dont le sport est utilisé pour générer ce pouvoir, et comment il peut contribuer à générer du contrôle ou à provoquer de l'influence, en se concentrant sur l'État du Qatar. Ce travail est séparé en trois parties principales. Je présente d'abord le développement du sport et la manière dont les événements sportifs ont été utilisés par différents pays et régimes politiques, ainsi que l'impact généré. Deuxièmement, j'essaie de comprendre l'impact généré par l'investissement du Qatar dans l'équipe de football française du Paris Saint-Germain. Et troisièmement, en mesurant l'impact socio-psychologique généré par la jeune génération en organisant des événements sportifs internationaux, le cas du championnat du monde de handball 2015. Ce travail vise à clarifier comment un tel investissement est perçu comme une opportunité de développement au sein de la société, et d'améliorer la diplomatie. En se concentrant sur l'évolution dont le sport est utilisé comme un outil important dans le processus de socialisation des jeunes dans la société mondiale. Sur la base de mes recherches, le résultat de l'investissement dans le Paris Saint-Germain était une situation «gagnant-gagnant» entre la France et le Qatar sur le plan social, économique et politique. De plus, l'utilisation des événements sportifs a eu un impact émotionnel positif, faisant admirer aux résidents la vision du gouvernement. La jeune génération, quelle que soit sa nationalité, a une vision positive des efforts du gouvernement pour s'améliorer et se développer. La vision du gouvernement du Qatar était saillante pour la jeune génération au Qatar
When we mention international relations, we generally talk about diplomacy and investment, but there are other ways of promoting the interests of a government on the international stage. Sport can be used as tool to improve diplomacy between countries, as well as developing economic and social interests. Additionally, sport takes an important place in shaping the image of a nation, while it improves the integration process of young generations into the world. One of the main interests, from a government perspective, in the use of sport, is to generate a positive emotional connection to a host nation - what is known as soft power. The aim of this work is to explore some of the ways in which sport is used to generate this power, and how it can provide a type of control or influence. Specifically, it will focus on the State of Qatar. This work is separated to three main parts. First I present the development of sport and the way sport events were used by different countries and political regimes, and the impact generated. Second, I try to understand the impact generated from Qatar investment in the French football team Paris Saint-Germain. And third, I measured the socio-psychological impact generated on the young generation from hosting international sport events, as in the case of the Handball World championship 2015.This work sets to clarify how allowing such investment is perceived as an opportunity for development within the society, and to improve diplomacy. Additionally, focussing on the young generation allows me to study the evolution of how sport is an important tool in the process of socialization of young people into global society. Based on my research, I argue that the result of the Paris Saint-Germain investment was a "win-win" situation between France and Qatar on the social, economic, and political level. Also, using sport events generated positive emotional impact, making the residents admire the vision of the government. The young generation, regardless nationality has a positive view of government efforts to improve and develop itself - the Qatari government's vision was salient to the young generation in Qatar

This thesis examines the social and environmental impacts that have resulted from the construction and operation of the Channel Tunnel. Nord-Pas de Calais, Kent, France, Britain and Europe were all affected through the establishment of the Channel Tunnel. Three sections make up the body of this thesis: i. context and theory ii. social, environmental and economic impacts associated with the construction and operation of the tunnel iii. acknowledgement of the impacts that this development has had on the European Union. This study draws from an extensive body of literature in identifying and examining the issues that preceded and followed this development. The social and environmental impacts associated with public opposition, environmental impacts, land possession, soil disposal, environmental disturbance, water pollution, noise disturbance, energy consumption, water contamination, fire safety and asylum seekers remain the principal discussion points identifiable throughout this piece. These issues are largely concentrated on the areas of Nord-Pas de Calais and Kent, although they are infiltrating the wider European Union in a number of ways. The social and environmental impact assessments conducted prior to the construction of the of the Channel Tunnel proved to be tools that helped ensure that the bodies driving the development were made accountable for the impacts that arose. These processes also facilitated public involvement through public consultation in the development of social and environmental impact assessment. Early identification and recognition of the social and environmental issues identified by these reports led to a more comprehensive approach to project design, construction and operation.

Les cratères d'impact hypervéloces sont les structures morphologiques les plus abondantes à la surface des corps planétaires telluriques du système solaire, sauf sur Terre où ils sont effacés par les processus de surface. La structure interne des cratères d'impact de type complexe ne peut être étudiée en détail que sur Terre par des études géophysiques et géologiques de terrain. De telles approches - combinées à de la modélisation - peuvent révéler comment le processus de cratérisation, la composition des roches cibles, l'érosion et d'autres processus post-impact peuvent conduire aux anomalies géophysiques observées, qui peuvent également être détectées par des données satellitaires sur d’autres planètes. La cartographie du champ magnétique, les mesures gravimétriques, les sondages électromagnétiques (EM34), les analyses paléomagnétiques, le magnétisme des roches et les techniques pétrographiques sont utilisées. Pour la première fois, nous révélons que la structure de Tunnunik récemment découverte présente des anomalies de gravité négative et de champ magnétique positif typiques, ce qui nous aide à reconsidérer l'étendue de la fracturation dans les roches cibles. La structure d’Haughton, moins érodée que Tunnunik, montre des signes d'une aimantation augmentée au centre de son soulèvement central, ce qui est causé par l’altération hydrothermale induite par l’impact. Le paléomagnétisme aide à contraindre les âges différents des deux impacts des lacs à l’eau claire au Québec. Ce travail a des implications importantes pour notre compréhension du processus de cratérisation dans le système solaire, notamment en ce qui concerne l'étude des surfaces planétaires
Hypervelocity impact craters are the most abundant morphologic features on rocky planetary bodies of the solar system, except on Earth where they are erased by surface processes. The internal structure of complex impact craters can only be studied on Earth by using ground-truth geophysical and geological studies. Such approaches - combined with modeling - can reveal how impact cratering, target geological composition, erosion and other post-impact processes can lead to the observed geophysical anomalies, which could also be detected by remote geophysical data on other planetary surfaces. Magnetic field mapping, gravimetry measurements, electromagnetic soundings (EM34), paleomagnetic analyses, rock magnetism and petrography techniques are used. For the first time, we reveal that the recently-discovered Tunnunik impact structure has typical negative gravity and positive magnetic field anomalies, which help us to reconsider the brecciation extent in the target rocks. The Haughton crater, which is less eroded than Tunnunik, shows evidence for an enhanced-magnetization in the core of the central uplift, caused by impact-generated hydrothermal alteration. Paleomagnetism helps to constrain the different ages of the East and west clearwater lake impacts. This work has important implications for our understanding of impact-cratering in the solar system, especially concerning the study of planetary surfaces

Low velocity impact behaviour of bi-layered laminates of acrylic and polycarbonate was investigated using a combination of drop tower impact experiments and explicit finite element analysis in LS-DYNA. Material characterisation tests were conducted in tension and in compression to obtain material properties for input to the material model in the numerical analysis. Quasistatic plate bending tests were conducted at different loading rates to compare the quasistatic response of the materials to the impact behaviour. Impact tests on circular plates of monolithic acrylic and polycarbonate were carried out using an instrumented drop weight impact tester. The impact force histories were recorded and a multiparameter approach was used to determine critical energy. Acrylic exhibited radial cracking, spalling and pene- tration while polycarbonate underwent large deformation and failed by dishing and plugging. The damage caused by impact in the bilayered laminate included partial or full delamination at the interface and radial cracks in the acrylic layer. The low velocity impact responses were simulated using 8-noded solid elements in LS- DYNA. A node-splitting technique based on maximum tensile stress failure criterion and an erosion approach based on maximum principal stress criteria was used to model the failure of acrylic. A material model that takes into account the asym- metric behaviour in tension and compression was investigated. The delamination between the acrylic and polycarbonate plate was modelled by a tiebreak contact with a shear strength based failure. The results of the finite element simulations are in good agreement with the experimental data.

京都大学
新制・課程博士
博士(エネルギー科学)
甲第23291号
エネ博第416号
京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻
(主査)教授 手塚 哲央, 教授 黒崎 健, 准教授 MCLELLAN Benjamin
学位規則第4条第1項該当
Doctor of Energy Science
Kyoto University
DFAM

An enhanced approach for the impact analysis is presented. Impact analyses play an important role in future research analysis as part of the scenario techniques in the strategic management field. Nowadays, they are also applied for the description of mutual relationships of tangible and intangible resources in organisations. The new method is based on currently existing methods using a cross impact matrix and overcomes some of their drawbacks. Indirect impacts are considered together with their impact strengths. A modification of the impact matrix is not necessary. Simple examples show that the new method leads to more reasonable and stable results than the existing methods. The new method shall help analysing the complexity of social systems in a more reliable way.

Natural disasters have always been and probably always will be a problem for humans and their settlements. With global warming seemingly increasing the frequency and strength of the climate related disasters, and more and more people being settled in urban centers, the ability to model and predict damage is more important than ever.The aim of this thesis has been to model and analyze a broad range of disaster types and the kind of impact that they have. By modeling damage indices for disaster types as different as hurricanes and volcanic eruptions, the thesis helps with understanding both similarities and differences between how disasters work and what impact they have on societies experiencing them. The thesis comprises four different chapters in addition to this introduction, where all of them include modeling of one or more types of natural disasters and their impact on real world scenarios such as local budgets, birth rates and economic growth.Chapter 2 is titled “Natural Disaster Damage Indices Based on Remotely Sensed Data: An Application to Indonesia". The objective was to construct damage indices through remotely sensed and freely available data. In short, the methodology exploits that one can use nightlight data as a proxy for economic activity. Then the nightlights data is matched with remote sensing data typically used for natural hazard modeling. The data is then used to construct damage indices at the district level for Indonesia, for different disaster events such as floods, earthquakes, volcanic eruptions and the 2004 Christmas Tsunami. The chapter is forthcoming as a World Bank Policy Research Paper under Skoufias et al. (2017a).Chapter 3 utilizes the indices from Chapter 2 to showcase a potential area of use for them. The title is “The Reallocation of District-Level Spending and Natural Disasters: Evidence from Indonesia" and the focus is on Indonesian district-level budgets. The aim was to use the modeled intensity from Chapter 2 to a real world scenario that could affect policy makers. The results show that there is evidence that some disaster types cause districts to move costs away from more general line items to areas such as health and infrastructure, which are likely to experience added pressure due to disasters. Furthermore, volcanic eruptions and the tsunami led to less investment into more durable assets both for the year of the disaster and the following year. This chapter is also forthcoming as a World Bank Policy Research Paper under Skoufias et al. (2017b).The fourth chapter, titled “Urban Global Impact of Earthquakes from 2004 through 2013", is a short chapter focusing on earthquake damage and economic growth. This chapter is an expansion of the index used in the previous two chapters, where we use global data instead of focusing on a single country. Using a comprehensive remotely sensed dataset of contour mapsof global earthquakes from 2004 through 2013 and utilizing global nightlights as an economic proxy we model economic impact in the year of the quakes and the year after. Overall, it is shown that earthquakes negatively impact local urban light emissions by 0.7 percent.Chapter 5 is named “A Whirlwind Romance: The Effect of Hurricanes on Fertility in Early 20th Century Jamaica" and deviates from the prior chapters in that it is a historical chapter that looks at birth rates in the early 1900s. The goal was to use the complete and long-term birth database for Jamaica and match this with hurricane data to check fertility rates. We create a hurricane destruction index derived from a wind speed model that we combine with data on more than 1 million births across different parishes in Jamaica. Analyzing the birth rate following damaging hurricanes, we find that there is a strong and significant negative effect of hurricane destruction on the number of births
Natural disasters have always been and probably always will be a problem for humans and their settlements. With global warming seemingly increasing the frequency and strength of the climate related disasters, and more and more people being settled in urban centers, the ability to model and predict damage is more important than ever.The aim of this thesis has been to model and analyze a broad range of disaster types and the kind of impact that they have. By modeling damage indices for disaster types as different as hurricanes and volcanic eruptions, the thesis helps with understanding both similarities and differences between how disasters work and what impact they have on societies experiencing them. The thesis comprises four different chapters in addition to this introduction, where all of them include modeling of one or more types of natural disasters and their impact on real world scenarios such as local budgets, birth rates and economic growth.Chapter 2 is titled “Natural Disaster Damage Indices Based on Remotely Sensed Data: An Application to Indonesia". The objective was to construct damage indices through remotely sensed and freely available data. In short, the methodology exploits that one can use nightlight data as a proxy for economic activity. Then the nightlights data is matched with remote sensing data typically used for natural hazard modeling. The data is then used to construct damage indices at the district level for Indonesia, for different disaster events such as floods, earthquakes, volcanic eruptions and the 2004 Christmas Tsunami. The chapter is forthcoming as a World Bank Policy Research Paper under Skoufias et al. (2017a).Chapter 3 utilizes the indices from Chapter 2 to showcase a potential area of use for them. The title is “The Reallocation of District-Level Spending and Natural Disasters: Evidence from Indonesia" and the focus is on Indonesian district-level budgets. The aim was to use the modeled intensity from Chapter 2 to a real world scenario that could affect policy makers. The results show that there is evidence that some disaster types cause districts to move costs away from more general line items to areas such as health and infrastructure, which are likely to experience added pressure due to disasters. Furthermore, volcanic eruptions and the tsunami led to less investment into more durable assets both for the year of the disaster and the following year. This chapter is also forthcoming as a World Bank Policy Research Paper under Skoufias et al. (2017b).The fourth chapter, titled “Urban Global Impact of Earthquakes from 2004 through 2013", is a short chapter focusing on earthquake damage and economic growth. This chapter is an expansion of the index used in the previous two chapters, where we use global data instead of focusing on a single country. Using a comprehensive remotely sensed dataset of contour mapsof global earthquakes from 2004 through 2013 and utilizing global nightlights as an economic proxy we model economic impact in the year of the quakes and the year after. Overall, it is shown that earthquakes negatively impact local urban light emissions by 0.7 percent.Chapter 5 is named “A Whirlwind Romance: The Effect of Hurricanes on Fertility in Early 20th Century Jamaica" and deviates from the prior chapters in that it is a historical chapter that looks at birth rates in the early 1900s. The goal was to use the complete and long-term birth database for Jamaica and match this with hurricane data to check fertility rates. We create a hurricane destruction index derived from a wind speed model that we combine with data on more than 1 million births across different parishes in Jamaica. Analyzing the birth rate following damaging hurricanes, we find that there is a strong and significant negative effect of hurricane destruction on the number of births

The purpose of this study was to assess the relationships between family/home satisfaction and job satisfaction of single working mothers with at least one child under the age of 18 living at home. The principal objectives were to identify the stressful situations in the lives of working single mothers and the factors that contributed to home satisfaction and work satisfaction. Data were gathered by survey questionnaire from single working mothers presently living in Iron County, Utah. Factor analysis was used to reduce data into home satisfaction and work satisfaction factors that were analyzed by multiple regression to determine the variance they explain. Stepwise multiple regression identified 1) family interaction, 2) income, housing, and health, and 3) family diet and money management as the home and family factors that predict satisfaction with home life. This multiple regression identified 1) family interaction, 2) time commitments, 3) income, housing, and health, 4) family and community support, and 5) family diet and money management as the home and family factors that can predict satisfaction with work. The work factors that can predict home life satisfaction were found to be 1) work schedule, 2) work environment, and 3 ) salary and advancement. Work factors that predict satisfaction with work were 1) breaks and control, 2) schedule and salary, and 3) commuting and friends at work. Working single mothers identified single parenting, financial problems, major changes in work or family, and problems with children as the situations causing stress in their lives. A statistically significant relationship was found with income and 1) education, 2) perception of enough income, 3) satisfaction with home life, and 4) work satisfaction.

Current assessments of research impact have been criticised for capturing what can be easily counted, not what counts. This thesis examines research impact and use in multiple ways, using childhood obesity prevention research and policy conducted and developed in New South Wales (NSW), Australia, between 2000 and 2015, as a case example. A broad systems lens is applied, with sub-studies examining specific aspects of this research-policy system in detail. A mix of quantitative and qualitative methods are used, including: systematic review; bibliometric analysis; citation analysis; document analysis; semi-structured interviews; and case studies. Firstly, the literature on research impact assessment is compared to that measuring policy utilisation of research. Secondly, the knowledge production context, including how and why research was conducted is investigated. Finally, research impact and use are assessed tracing forwards from research and backwards from policy, using a mix of narrow (research projects; policy documents) and broad (policy cases) units of analysis. The comparative approach used, empirically demonstrates how some methods of measuring impact restrict what can be defined and assessed as impact and therefore downplay the diverse ways in which research can influence policy processes. Different methods provide different perspectives of the relationship between research and policy, in terms of causation versus contribution. In addition, they give a different view of what is transferred, knowledge or research. Ultimately assessment needs to go beyond an understanding of research use as instrumental. This view determines the type of research that will be identified as impactful at the expense of other types of research. Looking beyond the efforts of individual researchers and research groups, to examine how systems support policy relevant knowledge production and use, may offer a way forward.

In the United States, biodiversity impact assessment has historically received little attention. Responding in 1993, the Council on Environmental Quality (CEQ) released guidelines on incorporating biodiversity into environmental impact assessment under the National Environmental Policy Act of 1969. The objectives of the study here were to identify the level of documentation of biodiversity impact assessment in sample Environmental Impact Statements (EISs); identify whether in the years following the release of 1993 CEQ guidelines any significant changes have taken place in assessment of biodiversity; identify deficiencies, and if the need exists, formulate appropriate recommendations and approaches for addressing biodiversity in EISs. The study involved a systematic review of 30 EISs published since the release of CEQ guidelines, and five EISs published prior to it. The review involved answering a series of standard questions, which attempted to ascertain the level of biodiversity impacts included in each impact statement. Trends in approaches to biodiversity impact assessment were investigated and deficiencies summarized. The analysis resulted in a series of recommendations for improving the manner in which biodiversity impact assessment can be approached.

Les composites thermoplastiques sont de plus en plus privilégiées dans les structures aérospatiales au vue de leur tolérance aux dommages améliorée par rapport aux résines thermodurcissables. Néanmoins, ils restent sensibles à l’impact car il produit des endommagements complexes au sein du matériau, dont le délaminage est le plus critique. La propagation de ces endommagements en compression après impact (CAI) entraîne une réduction de la tenue résiduelle. D’abord, des essais ENF ont été menés afin de déterminer la ténacité interfaciale par le biais de la méthode de la complaisance et de la technique de thermographie infrarouge. Ensuite, l’essai « Short Beam Shear » est proposé afin d’investiguer le couplage entre la fissuration matricielle et le délaminage. L’effet de la vitesse de sollicitation a été également étudié. La valeur de ténacité mesurée semble indépendante à la vitesse de sollicitation car, lors des essais réalisés, la propagation est instable. Ensuite, le comportement d’une éprouvette académique été étudié à l’aide du « Discrete Ply Model » (DPM) permettant d’enchaîner la simulation d’impact et de CAI. Ce modèle est basé sur une approche semi-discrète modélisant le délaminage et la fissuration matricielle par des éléments cohésifs, permettant de prendre en compte le couplage entre ces deux endommagements. Une vaste campagne d'essais expérimentaux d’impact et de CAI a été mise en place sur quatre empilements différents impactés à trois niveaux d’énergie. Le modèle DPM a prouvé sa capacité à prédire correctement les endommagements d’impact et de CAI. Finalement, afin de se rapprocher des conditions de structures réelles, le comportement en compression après impact d’une plaque trouée a été investigué
High-performance thermoplastic composite have been increasingly used in aerospace applications because of their advantageous mechanical properties. Nevertheless, impact damage leads to significant reduction in structure compressive strength although damage may remain unnoticed. Delamination is the most critical damage. Short Beam Shear (SBS) test has been proposed to reproduce impact damage chronology and characterize delamination toughness. Infrared thermography is used for local measuring of fracture toughness in this unclassical test showing unstable fracture growth. Mode II fracture toughness (GIIC) values are comprised between 0.9 and 1.7 N/mm and there was no influence of the loading rate in GIIC values. Discrete Ply Model (DPM) is therefore used to model impact and compression after impact tests on laminated composite structures. Tests have been conducted in order to validate DPM capacity to capture the effects of progressive damage and failure. Impact damage and specimen’s compressive strength is well predicted by DPM. CAI damage propagation is driven by the buckling of the structure. DPM is finally employed to study impact on an industrial sample with a large diameter hole. Impact damage correlates with tests but buckling is difficult to estimate, meaning that rupture of the specimen does not correlate to tests. Nevertheless, DPM shows a good ability to predict damage in thermoplastic composite

Hybrid polymer laminates of polycarbonate and PMMA have generated considerable interest among researchers as an alternative to traditional glass armours because of their potential for reduced cost and weight. Generally, the development of ballistic armour is carried out experimentally which is an expensive task in terms of time and cost. Numerical simulation provides a much greater facility to understand the phenomenon of ballistic impact and the effects of various parameters on the response to such impact. In addition it provides an easy means of comparing the impact performance of different materials as well as combination of materials forming hybrid laminates. The aim of this research was to develop a numerical modelling capability to simulate the ballistic response of hybrid polymer laminates, specifically polycarbonate and PMMA, using a commercially available finite element code LS-DYNA. The challenge was to work within the limitations of the material models and the failure algorithms available within LS-DYNA, and still try to reproduce the behaviour observed experimentally by previous researchers, initially on monolithic plates of polycarbonate and PMMA and then on hybrid laminates. The first part of the study focuses on a detailed literature survey on mechanical and dynamic characterisation of polycarbonate and PMMA as well as experimental and numerical studies previously conducted on ballistic behaviour of these materials as well as their combinations. The material properties of the polymers compiled from this literature survey were used as input for the selected LS-DYNA material model. Impact simulations were carried on monolithic and laminated media of polycarbonate and PMMA and where possible these were compared to experimental results. It was observed that the results agreed with the experimental data qualitatively. Quantitatively the results showed some discrepancies which were attributed to the limitations faced in simulating the exact test conditions numerically. Numerical simulations were carried out to study the effects of variations in laminate thickness and plate support diameters as well as to examine the influence of the bond between the layers. Finally the impact response of four different combinations of polycarbonate and PMMA are compared to each other for different laminate thicknesses.

L'etude d'impact est analysee en tant qu'outil d'aide a la decision et a la conception et son role dans la negociation sociale et la gestion de l'environnement est determine. Les limites absolues a l'evaluation de l'impact d'un projet minier sont conferees par les specificites du projet, a savoir: sa singularite et l'incertitude liee au fait que la connaissance du gisement est, toujours imparfaite. Sa dynamique interne et externe et sa rigidite spatiale. L'importance du suivi des impacts reels des projets et de la conception de la gestion de l'environnement comme partie integrante de la gestion du projet est soulignee

Impact E/P copolymer (ICP) is produced using gas-phase polymerization catalysed by Ziegler-Natta catalysts. This material with its excellent mechanical properties is used in many industries, for example in automotive industry to produce bumpers or instrument panels. Its properties depend on chemical structure which was analysed using DSC, 13C NMR and GPC. It was used 6 different samples of ICP for studies, the chosen samples have different ratio between ethylene and propylene in their copolymer phase. The samples were fractionated using preparative TREF and solvent extraction to obtain fractions, which composition depends on elution temperature. Obtained fractions and original samples were subsequently analysed using above-mentioned methods.

Die Inositolmonophosphatase (IMPase) reguliert als Schlüsselenzym des Phosphatidyl-Inositol-Signalwegs den Abbau des second messenger Inositoltrisphophat (IP3). Als wahrscheinliche molekulare Zielstruktur in der Behandlung der Bipolar Affektiven Störung ist die Erforschung der Regulation der IMPase von hoher medizinischer Relevanz. Seit Jahrzehnten werden Lithiumsalze, die die IMPase in therapeutischen Konzentrationen hemmen, in der Prophylaxe manischer Phasen eingesetzt. Die Therapie mit Lithiumsalzen birgt jedoch die Gefahr zahlreicher schwerwiegender Nebenwirkungen. Außerdem besitzt das Medikament eine geringe therapeutische Breite. Dies macht die Untersuchung alternativer Regulationsmöglichkeiten der IMPase als möglichem Ansatzpunkt für neue pharmakologische Therapien der Bipolar Affektiven Störung hochinteressant. In den letzten Jahren mehrten sich die Hinweise auf eine Regulation der IMPase durch Ca2+-bindende Proteine. Im Rahmen dieser Arbeit wurde mittels verschiedener in vitro-Methoden der Einfluss der Ca2+-bindenen Proteine Calbindin D28k (CB) sowie Calmodulin (CaM) auf die Enzymaktivität der IMPase untersucht. Hierzu wurden die Proteine heterolog in E. coli exprimiert und ein Phosphat-Akkumulationsassay zur Untersuchung der Enzymaktivität der IMPase etabliert. Für die funktionellen Untersuchungen mit CB konnte eine signifikante Steigerung der Aktivität der IMPase nachgewiesen werden. Im Vorfeld der funktionellen Untersuchungen der Enzymaktivität mit CaM konnte eine Ca2+-abhängige Bindung von CaM an die IMPase mittels zweier unabhängiger Experimente gezeigt werden. Da die freie Ca2+-Konzentration einen hemmenden Einfluss auf die Aktivität der IMPase hat, wurde die Ca2+-Bindung durch CaM mit einem Fluoreszenz-Assay kontrolliert. Hierdurch konnten die funktionellen Experimente mit CaM unter genau definierten Ca2+-Konzentrationen durchgeführt werden. In den funktionellen Untersuchungen mit CaM zeigte sich keine Modulation der IMPase. Weiterführende Experimente sollten der Identifizierung möglicher zusätzlicher Interaktionspartner der IMPase dienen. Dazu würden sich Immunpräzipitationsexperimente anbieten. Außerdem sollte eine Untersuchung der Interaktion zwischen IMPase und CaM in einem eukaryotischen Zellsystem erfolgen. Dies würde eine Aussage unter physiologischen Bedingungen ermöglichen.

Activities, conducted in the logistics sector, contribute to pollute the world. Especially, road transportation contaminates the environment with the release of exhaust emissions. Transport volumes as well as the proportion of the road sector are constantly rising, which intensifies its environmental impacts. In order to determine the main culprits of pollution, Environmental Impact Analysis (EIA) are used. These concepts are mostly ambiguous, fuzzy and hard to present in a comprehensive way. The main purpose of the present thesis is to develop an analysis in order to investigate the environmental impacts of road transportation along a certain supply chain. An academic resource was used as database, in order to develop and test an exhauste mission calculation in cooperation with a case company. Besides CO2, this assessment also focuses on the measurement of other exhauste missions like Nox, PM or CO. Furthermore, economic factors like, costs caused per transport are calculated. Aspects, like capacity utilization, the use of environmentally friendly tires or eco-friendly driving styles, are included in the analysis. These factors influence fuel consumption and thus the final production of exhaust emissions. A detailed description of each factor and calculation step is illustrated in this thesis. Due to a high complexity of transportation, this analysis is limited to road transportation. The fundament of the analysis builds the categorization of crafts due to the Euro standards. Hence, just transports conducted with crafts, manufactured within the European Union, can be evaluated. A validation test and in-depth interviews were conducted in order to approve the practicability of the developed assessment. During this process, strengths and weaknesses of the analysis were identified. Finally, the analysis is critically examined by showing its application constraints as well as prospective development opportunities. An enlargement, to include other transport modes, material handling activities in order to measure impacts during intermodal transportation along a whole transportation chain, is a prospect outlook.

The purposes of the study were to measure change in knowledge, adoption of practices, and economic impact, and to investigate relationships between selected personal and business parameters, and satisfaction, knowledge, adoption of practices, and economic impact of the Master Marketer program and marketing clubs. A census was attempted to collect data from the 520 Master Marketer graduates and 1,058 marketing club members. Using recommendations from Dillman (2000), data from participants were collected using two mail questionnaires. This process yielded 326 usable responses from Master Marketer graduates for a return rate of 62.7%, and 407 usable responses from marketing club members for a response rate of 38.4%. Master Marketer respondents had a statistically significant increase in selfperceived knowledge with a change in mean score of 2.06 (pre-knowledge mean = 3.33, post-knowledge mean = 5.40, where 1 = low, and 7 = excellent). Using a paired samples t-test, the 2-tail level of significance was beyond the .05 level of significance. Marketing club respondents also showed a statistically significant increase in self-perceived knowledge. Adoption of price risk management practices was measured with an adjusted response scale ranging from 0 to 12. Master Marketer respondents showed a pre-mean score of 3.15, a post-mean score of 6.61, and a change of 3.46. The 2-tailed level of significance for the overall adoption scale was less than 0.01. Marketing club respondents also showed a statistically significant increase in adoption of these practices. Economic impact in terms of change in net income was derived using respondents?? self-reported changes in commodity price received for each commodity produced, and each respondent??s typical level of production. The total farm impact had a mean of $32,288. The 2-tailed level of significance for the total farm impact was less than 0.01. The mean impact per farm of $12,361 for marketing club respondents was also statistically significant. For Master Marketer respondents, notable findings with respect to the correlation of independent variable with dependent variables was total gross revenue was negatively correlated with knowledge change. Participants who reported a large change in knowledge tended to also report a large change (increase) in time spent on marketing.

This Thesis investigates the number of possible meteorite impacts in Sweden since the year 2000. Sweden did not until recently have any photographic monitoring of incoming meteorites, thus a search through media reporting observations from the public has been performed. A theoretical approximation, based on an established extra-terrestrial mass ux, gives the number of 210 possible meteorite impacts for this time period. All of these could have been reballs, but by subtracting the daylight hours and bad weather conditions, only 47 reballs could have been seen during the 15 years. All of the 210 events could also have dropped meteorites on the ground, but when subtracting areas where it is very unlikely to recover a meteorite, like large forest areas and lakes, the number of possible meteorites is 73. The newspaper articles published since 2000 regarding reball observations gives 37 plausible meteorites. The theoretical value and the number of observations are similar enough that the theoretical approximation is probable to be correct.

Includes bibliographical references.
This dissertation reports on the results of an experimental and numerical investigation into the response of different materials to air-blast loading. Mild steel, armour steel (Armox 370T and 440T), Aluminium alloy 5083-H116, Twintex and Dyneema square plates were blast loaded on a horizontal pendulum at the Blast Impact and Survivability Research Unit (BISRU), University of Cape Town. The blasts were generated by detonating disc-shaped PE4 explosives of various diameters and standoff distances. The chosen plates are of side length 500mm (4mm thick mild steel and armour steel plates) and side length of 400mm (aluminium, Twintex and Dyneema panels). The charge mass was varied between 9g and 60g for two charge diameters, namely: 50mm and 75mm, and stand-off distances of 25mm, 38mm and 50mm. A polystyrene bridge was used to position the charges at the centre of plates, without any polystyrene between the charge and the plate in order to minimise any effects the polystyrene may have had on the plate deformation. The transient response of the 500mm square plates (mild steel and Armox 370T) was measured with the use of Light Interference Equipment (LIE) and numerical simulations performed in ANSYS AUTODYN, with the aim of gaining greater insight into the response of the two different materials. The details of the experimental setup and method used for the LIE as well as the development of the AUTODYN computational model are presented. The air and explosive were modelled as Arbitrary Langrange-Euler (ALE) elements while the test plates were modelled as Langrangian shell elements. Since the geometry of the plates was square, the simulations had to be performed in 3D quarter-symmetry. The transient response, permanent final displacement and maximum transient displacement of the numerical simulations were compared to the corresponding experimental results. The mild steel plates all exhibited good correlation between experimental and simulated results. However, the Armox 370T simulated results showed an under-prediction of the displacement magnitude and impulse compared to the experimental results. Experimentally, both the mild steel and armour steel exhibited a linear increase in deformation with increasing charge mass. Blast tests were also performed on 3mm thick mild steel, aluminium, Twintex and Dyneema square plates of 400mm side length. The aim was to gain a greater understanding and compare of the response of different material types (ferrous, non-ferrous, Glass Fibre Polypropylene and Ultra High Molecular Weight Polyethylene) under blast loading. The aluminium plates performed better than the mild steel, on an equivalent mass basis, in terms of permanent displacements and failure threshold impulse. The aluminium plates were significantly thicker (10.5mm compared to 3mm) than the mild steel plates, which may have contributed to its response under blast. The Twintex panels mostly exhibited failure in the form of fibre fracture and matrix failure whereas the Dyneema panels only exhibit large inelastic deformation, although the Dyneema were clamped differently to the other panels. Dimensionless analysis was performed on all of the materials except for Dyneema. Initially a scaling factor was used to account for the varying stand-off distances but proved to be unnecessary due to the type of confinement used (unconfined free air-blasts versus partially confined tube). Once the scaling factor was removed, the dimensionless impulse values showed relatively good linear correlation with the predicted trend.

Orientador: Leandro Eugenio da Silva Cerri
Banca: Fábio Augusto Gomes de Vieira Reis
Banca: Flávio Henrique Mingante Schlittler
Resumo: A avaliação da significância dos impactos ambientais continua a ser um importante componente crítico ainda mal compreendido da prática da avaliação de impactos ambientais. Este trabalho é um estudo sobre as conclusões de uma revisão bibliográfica sobre a avaliação e comunicação de avaliação do impacto ambiental praticada no Brasil. É dada especial atenção para a importância da utilização de critérios, padrões e métodos de avaliação de impactos ambientais que pretendendo incorporar mais eficiência nos estudos de impacto ambiental. Assim, o objetivo desta pesquisa foi a realização de uma proposta, incluindo o desenvolvimento de procedimentos e aplicar na avaliação de impactos ambientais situações relativas à sua formulação, aplicação e interpretação da significância dos critérios, conclusões e recomendações pertinentes para respeitar o objetivo da avaliação de impacto ambiental que é garantir a viabilidade ambiental das atividades humanas.
Abstract: The evaluation of the significance of environmental impacts remains an important critical yet poorly understood component of environmental impact assessment practice. This work is a study upon the findings of a bibliographic review about the evaluation and communication of environmental impact assessment in Brazil practice. Particular attention is given to the use of significance criteria, thresholds and EIA methodologies intending to incorporate more efficiency of environmental impact statement. Thus, the aim of this research was the accomplishment of a proposal including the development of procedures to apply in EIA issues surrounding the formulation, application and interpretation of significance criteria, conclusions and recommendations relevant to respect the aim of EIA that in provide environmental viability of men activities.
Mestre

[Context] Social impact refers to the positive and negative consequences of any organization on the environment and society. One actor in the social impact landscape is the impact investor who expects financial return for their investments as well as positive social impact. Although the impact investor plays a crucial role in the social impact capital market by financing organizations that explicitly address social and environmental problems, the academic literature regarding impact investing has yet to develop especially from the investor perspective. One reason for the lack of academic research in this field is that the impact investor stands at a crossroad, between social impact and social enterprise research. [Purpose] Therefore, the purpose of this research is to determine the current state of impact investment processes as well as the challenges that investors face and, lastly, the role of social impact measurement within the impact investing process. [Findings] An exploratory multi-case study was conducted with semi-structured interviews which resulted in eight interviews from impact investors across four countries and within different focus areas in the social impact landscape. The findings show that impact investors face a variety of challenges based on the stage of their portfolio enterprises, the alignment of the social enterprise’s business model with their social impact mission, the horizon of their investments and, last but not least, their investment exit strategies. As for the role of social impact measurement in the investment process, the findings show that the majority of impact investors measure the impact of their investments although the method of measurement varies while the remaining investors, that do not measure social impact, illustrate the challenges that come with measuring impact in their personal contexts such as the difficulty of measuring the impact of an early stage social enterprise that may be susceptible to pivots.
[Kontext] Social påverkan avser de positiva och negativa konsekvenserna av alla organisationer på miljön och samhället. En aktör i det sociala påverkanslandskapet är påverkansinvesterare som förväntar sig ekonomisk avkastning för sina investeringar samt positiva sociala effekter. Även om påverkansinvesterare spelar en avgörande roll på kapitalmarknaden för social påverkan genom att finansiera organisationer som uttryckligen behandlar sociala och miljömässiga problem, har den akademiska litteraturen angående impact investering ännu inte utvecklats särskilt ur investerarperspektivet. En anledning till bristen på akademisk forskning inom detta område är att påverkansinvesterare står vid en korsning mellan social påverkan och social företagsforskning. [Syfte] Syftet med denna forskning är därför att undersöka det aktuella tillståndet för effekterna av investeringsprocesser samt de utmaningar som investerare står inför och slutligen rollen för mätning av sociala effekter i effekten av investeringsprocessen. [Resultat] En undersökande multifallstudie genomfördes med semistrukturerade intervjuer som resulterade i åtta intervjuer från påverkansinvesterare i fyra länder och inom olika fokusområden i det sociala påverkanslandskapet. Resultaten visar att påverkansinvesterare möter olika utmaningar baserat på affärsfas i deras portföljföretag, anpassningen av det sociala företagets affärsmodell med deras sociala påverkan, deras investeringshorisont och, sist men inte minst, deras investeringsutgångsstrategier . När det gäller rollen för mätning av sociala konsekvenser i investeringsprocessen visar resultaten att majoriteten av påverkansinvesterare mäter effekterna av sina investeringar även om mätmetoden varierar medan de återstående investerarna, som inte mäter social påverkan, illustrerar de utmaningar som komma med att mäta påverkan i deras personliga sammanhang, såsom svårigheten att mäta effekterna av ett tidigt skede socialt företag som kan vara känsligt för svängningar.

[Context] Social impact refers to the positive and negative consequences of any organization on the environment and society. One actor in the social impact landscape is the impact investor who expects financial return for their investments as well as positive social impact. Although the impact investor plays a crucial role in the social impact capital market by financing organizations that explicitly address social and environmental problems, the academic literature regarding impact investing has yet to develop especially from the investor perspective. One reason for the lack of academic research in this field is that the impact investor stands at a crossroad, between social impact and social enterprise research. [Purpose] Therefore, the purpose of this research is to determine the current state of impact investment processes as well as the challenges that investors face and, lastly, the role of social impact measurement within the impact investing process. [Findings] An exploratory multi-case study was conducted with semi-structured interviews which resulted in eight interviews from impact investors across four countries and within different focus areas in the social impact landscape. The findings show that impact investors face a variety of challenges based on the stage of their portfolio enterprises, the alignment of the social enterprise’s business model with their social impact mission, the horizon of their investments and, last but not least, their investment exit strategies. As for the role of social impact measurement in the investment process, the findings show that the majority of impact investors measure the impact of their investments although the method of measurement varies while the remaining investors, that do not measure social impact, illustrate the challenges that come with measuring impact in their personal contexts such as the difficulty of measuring the impact of an early stage social enterprise that may be susceptible to pivots.
[Kontext] Social påverkan avser de positiva och negativa konsekvenserna av alla organisationer på miljön och samhället. En aktör i det sociala påverkanslandskapet är påverkansinvesterare som förväntar sig ekonomisk avkastning för sina investeringar samt positiva sociala effekter. Även om påverkansinvesterare spelar en avgörande roll på kapitalmarknaden för social påverkan genom att finansiera organisationer som uttryckligen behandlar sociala och miljömässiga problem, har den akademiska litteraturen angående impact investering ännu inte utvecklats särskilt ur investerarperspektivet. En anledning till bristen på akademisk forskning inom detta område är att påverkansinvesterare står vid en korsning mellan social påverkan och social företagsforskning. [Syfte] Syftet med denna forskning är därför att undersöka det aktuella tillståndet för effekterna av investeringsprocesser samt de utmaningar som investerare står inför och slutligen rollen för mätning av sociala effekter i effekten av investeringsprocessen. [Resultat] En undersökande multifallstudie genomfördes med semistrukturerade intervjuer som resulterade i åtta intervjuer från påverkansinvesterare i fyra länder och inom olika fokusområden i det sociala påverkanslandskapet. Resultaten visar att påverkansinvesterare möter olika utmaningar baserat på affärsfas i deras portföljföretag, anpassningen av det sociala företagets affärsmodell med deras sociala påverkan, deras investeringshorisont och, sist men inte minst, deras investeringsutgångsstrategier . När det gäller rollen för mätning av sociala konsekvenser i investeringsprocessen visar resultaten att majoriteten av påverkansinvesterare mäter effekterna av sina investeringar även om mätmetoden varierar medan de återstående investerarna, som inte mäter social påverkan, illustrerar de utmaningar som komma med att mäta påverkan i deras personliga sammanhang, såsom svårigheten att mäta effekterna av ett tidigt skede socialt företag som kan vara känsligt för svängningar.

Dans un souci majoritaire de gain en masse et pour l’intégration de solutions innovantes et de structures hautes performances dans les applications actuelles, les matériaux composites occupent une place grandissante au sein des structures aéronefs. Cependant, ils restent vulnérables aux sollicitations hors-plan tel que l’impact, dues par exemple à une chute d’objet pendant une opération de maintenance. Cet événement peut drastiquement réduire leur tenue résiduelle sans pour autant laisser de marque visible en surface. Pour répondre aux exigences réglementaires et permettre une utilisation saine en service, les structures composites sont donc souvent surdimensionnées.Ces travaux de thèse portent sur l’étude expérimentale et numérique de la tolérance aux dommages d’impact (TDI) d’un stratifié composite aéronautique. Entre méthodologie et technique, le thème de recherche propose une étude complète de l’intégrité d’une structure composite, permettant l’apport de connaissances ainsi qu’une compréhension approfondie de la TDI.Le dimensionnement des structures composites s’appuie sur les méthodes aéronautiques d’inspection visuelle des endommagements définissant les charges acceptables et requises par la structure. En effet, la détectabilité de l’endommagement permet une intervention de réparation sur la structure : tant que l’endommagement n’est pas détecté (BVID : Barely Visible Impact Damage), les performances de la structure doivent rester élevées. De nouveaux concepts de stratifiés composites hybrides sont proposés puis testés expérimentalement dans le but d’améliorer la TDI et d’approfondir également la connaissance du comportement des stratifiés composites. Ces concepts sont établis à partir d’un cas de référence, ensuite décliné sous différentes configurations de stratifiés composites hybrides. La démarche expérimentale de la TDI est alors menée depuis l’impact jusqu’à la compression après impact pour définir les deux indicateurs principaux de cette étude : l’indentation permanente et la tenue résiduelle.En parallèle, le modèle développé à l’ICA, le Discret Ply Model (DPM), est utilisé pour proposer une démarche de dimensionnement de stratifié intégrant la philosophie de la TDI. Des améliorations de modélisation et son extension aux stratifiés composites hybrides sont ensuite proposées. Elles ouvrent sur l’utilisation du DPM comme un outil d’aide au dimensionnement des structures composites. Cette démarche est en parfaite cohérence avec l’intégration des approches numériques pour assister les études expérimentales, s’intégrant dans le cadre du « Virtual Testing »
Coupling with will of mass gain, use of innovative solutions and high performance structures in today’s industrial applications, composites are more and more present in aeronautical structures. However, they are still vulnerable to out-of-plane loading such as impact, due to falling objects during a maintenance operation for instance. This event can drastically reduce their residual strength without let a visible mark onto the surface. Therefore in order to meet requirements and drive to healthy use in service, composites structures are often oversized.This work deals with the experimental and numerical study of the Impact Damage Tolerance (IDT) of an aeronautical composite laminate. An overall study of composite structures integrity leads to a deeper knowledge of the IDT.The approach is based on aeronautical methods for the damages visual inspection: the damage detectability defines the required load that the structure has to sustain. Indeed, the detectability of the damage allows a repair intervention on the structure: as long as the damage is not detectable (BVID), the performance of the structure must remain high. Proposed concepts are experimentally tested to improve the TDI and to bring to more understanding in the behavior of composite laminates. These concepts are based on a reference case, and then declined under different configurations of hybrid composite laminates. The experimental approach of TDI is carried out from impact to compression after impact to define the two main indicators: permanent indentation and residual strength.The model developed at ICA, the Discrete Ply Model (DPM), is used to propose a numerical designing approach according to the TDI philosophy. Modeling improvements are implemented to extend to hybrid composite laminates. This step opens up on the use of DPM as a tool to assist the composite structures sizing. This advanced is in respect with the integration of numerical approaches to support experimental studies, integrating within the framework of "Virtual Testing"

Evaluation of the performance of a product and its components under impact loading is one of the key considerations in design. In order to assess resistance to damage or ability to absorb energy through plastic deformation of a structural component, impact testing is often carried out to obtain the 'Force - Displacement' response of the deformed component. In this context, it may be noted that load cells and accelerometers are commonly used as sensors for capturing impact responses. A drop-weight impact testing set-up consisting of a moving impactor head with a lightweight piezoresistive accelerometer and a strain gage based compression load cell mounted on it is used to carry out the impact tests. The basic objective of the present study is to assess the accuracy of responses recorded by the said transducers, when these are mounted on a moving impactor head. In the present work, a novel approach of theoretically evaluating the responses obtained from this drop-weight impact testing set-up for different axially loaded specimen has been executed with the formulation of an equivalent lumped parameter model (LPM) of the test set-up. For the most common configuration of a moving impactor head mounted load cell system in which dynamic load is transferred from the impactor head to the load cell, a quantitative assessment is made of the possible discrepancy that can result in load cell response. Initially, a 3-DOF (degrees-of-freedom) LPM is considered to represent a given impact testing set-up with the test specimen represented with a nonlinear spring. Both the load cell and the accelerometer are represented with linear springs, while the impacting unit comprising an impactor head (hammer) and a main body with the load cell in between are modelled as rigid masses. An experimentally obtained force-displacement response is assumed to be a nearly true behaviour of a specimen. By specifying an impact velocity to the rigid masses as an initial condition, numerical solution of the governing differential equations is obtained using Implicit (Newmark-beta) and Explicit (Central difference) time integration techniques. It can be seen that the model accurately reproduces the input load-displacement behaviour of the nonlinear spring corresponding to the tested component, ensuring the accuracy of these numerical methods. The nonlinear spring representing the test specimen is approximated in a piecewise linear manner and the solution strategy adopted and implemented in the form of a MATLAB script is shown to yield excellent reproduction of the assumed load-displacement behaviour of the test specimen. This prediction also establishes the accuracy of the numerical approach employed in solving the LPM system. However, the spring representing the load cell yields a response that qualitatively matches the assumed input load-displacement response of the test specimen with a lower magnitude of peak load. The accelerometer, it appears, may be capable of predicting more closely the load experienced by a specimen provided an appropriate mass of the impactor system i.e. impacting unit, is chosen as the multiplier for the acceleration response. Error between input and computed (simulated) responses is quantified in terms of root mean square error (RMSE). The present study additionally throws light on the dependence of time step of integration on numerical results. For obtaining consistent results, estimation of critical time step (increment) is crucial in conditionally stable central difference method. The effect of the parameters of the impact testing set-up on the accuracy of the predicted responses has been studied for different combinations of main impactor mass and load cell stiffness. It has been found that the load cell response is oscillatory in nature which points out to the need for suitable filtering for obtaining the necessary smooth variation of axial impact load with respect to time as well as deformation. Accelerometer response also shows undulations which can similarly be observed in the experimental results as well. An appropriate standard SAE-J211 filter which is a low-pass Butterworth filter has been used to remove oscillations from the computed responses. A load cell is quite capable of predicting the nature of transient response of an impacted specimen when it is part of the impacting unit, but it may substantially under-predict the magnitudes of peak loads. All the above mentioned analysis for a 3 DOF model have been performed for thin-walled tubular specimens made of mild steel (hat-section), an aluminium alloy (square cross-section) and a glass fibre-reinforced composite (circular cross-section), thus confirming the generality of the inferences drawn on the computed responses. Further, results obtained using explicit and implicit methodologies are compared for three specimens, to find the effect, if any, on numerical solution procedure on the conclusions drawn. The present study has been further used for investigating the effects of input parameters (i.e. stiffness and mass of the system components, and impact velocity) on the computed results of transducers. Such an investigation can be beneficial in designing an impact testing set-up as well as transducers for recording impact responses. Next, the previous 3 DOF model representing the impact testing set-up has been extended to a 5 DOF model to show that additional refinement of the original 3 DOF model does not substantially alter the inferences drawn based on it. In the end, oscillations observed in computed load cell responses are analysed by computing natural frequencies for the 3 DOF lumped parameter model. To conclude the present study, a 2 DOF LPM of the given impact testing set-up with no load cell has been investigated and the frequency of oscillations in the accelerometer response is seen to increase corresponding to the mounting resonance frequency of the accelerometer. In order to explore the merits of alternative impact testing set-ups, LPMs have been formulated to idealize test configurations in which the load cell is arranged to come into direct contact with the specimen under impact, although the accelerometer is still mounted on the moving impactor head. One such arrangement is to have the load cell mounted stationary on the base under the specimen and another is to mount the load cell on the moving impactor head such that the load cell directly impacts the specimen. It is once again observed that both these models accurately reproduce the input load-displacement behaviour of the nonlinear spring corresponding to the tested component confirming the validity of the model. In contrast to the previous set-up which included a moving load cell not coming into contact with the specimen, the spring representing the load cell in these present cases yields a response that more closely matches the assumed input load-displacement response of a test specimen suggesting that the load cell coming into direct contact with the specimen can result in a more reliable measurement of the actual dynamic response. However, in practice, direct contact of the load cell with the specimen under impact loading is likely to damage the transducer, and hence needs to be mounted on the moving head, resulting in a loss of accuracy, which can be theoretically estimated and corrected by the methodology investigated in this work.

Evaluation of the performance of a product and its components under impact loading is one of the key considerations in design. In order to assess resistance to damage or ability to absorb energy through plastic deformation of a structural component, impact testing is often carried out to obtain the 'Force - Displacement' response of the deformed component. In this context, it may be noted that load cells and accelerometers are commonly used as sensors for capturing impact responses. A drop-weight impact testing set-up consisting of a moving impactor head with a lightweight piezoresistive accelerometer and a strain gage based compression load cell mounted on it is used to carry out the impact tests. The basic objective of the present study is to assess the accuracy of responses recorded by the said transducers, when these are mounted on a moving impactor head. In the present work, a novel approach of theoretically evaluating the responses obtained from this drop-weight impact testing set-up for different axially loaded specimen has been executed with the formulation of an equivalent lumped parameter model (LPM) of the test set-up. For the most common configuration of a moving impactor head mounted load cell system in which dynamic load is transferred from the impactor head to the load cell, a quantitative assessment is made of the possible discrepancy that can result in load cell response. Initially, a 3-DOF (degrees-of-freedom) LPM is considered to represent a given impact testing set-up with the test specimen represented with a nonlinear spring. Both the load cell and the accelerometer are represented with linear springs, while the impacting unit comprising an impactor head (hammer) and a main body with the load cell in between are modelled as rigid masses. An experimentally obtained force-displacement response is assumed to be a nearly true behaviour of a specimen. By specifying an impact velocity to the rigid masses as an initial condition, numerical solution of the governing differential equations is obtained using Implicit (Newmark-beta) and Explicit (Central difference) time integration techniques. It can be seen that the model accurately reproduces the input load-displacement behaviour of the nonlinear spring corresponding to the tested component, ensuring the accuracy of these numerical methods. The nonlinear spring representing the test specimen is approximated in a piecewise linear manner and the solution strategy adopted and implemented in the form of a MATLAB script is shown to yield excellent reproduction of the assumed load-displacement behaviour of the test specimen. This prediction also establishes the accuracy of the numerical approach employed in solving the LPM system. However, the spring representing the load cell yields a response that qualitatively matches the assumed input load-displacement response of the test specimen with a lower magnitude of peak load. The accelerometer, it appears, may be capable of predicting more closely the load experienced by a specimen provided an appropriate mass of the impactor system i.e. impacting unit, is chosen as the multiplier for the acceleration response. Error between input and computed (simulated) responses is quantified in terms of root mean square error (RMSE). The present study additionally throws light on the dependence of time step of integration on numerical results. For obtaining consistent results, estimation of critical time step (increment) is crucial in conditionally stable central difference method. The effect of the parameters of the impact testing set-up on the accuracy of the predicted responses has been studied for different combinations of main impactor mass and load cell stiffness. It has been found that the load cell response is oscillatory in nature which points out to the need for suitable filtering for obtaining the necessary smooth variation of axial impact load with respect to time as well as deformation. Accelerometer response also shows undulations which can similarly be observed in the experimental results as well. An appropriate standard SAE-J211 filter which is a low-pass Butterworth filter has been used to remove oscillations from the computed responses. A load cell is quite capable of predicting the nature of transient response of an impacted specimen when it is part of the impacting unit, but it may substantially under-predict the magnitudes of peak loads. All the above mentioned analysis for a 3 DOF model have been performed for thin-walled tubular specimens made of mild steel (hat-section), an aluminium alloy (square cross-section) and a glass fibre-reinforced composite (circular cross-section), thus confirming the generality of the inferences drawn on the computed responses. Further, results obtained using explicit and implicit methodologies are compared for three specimens, to find the effect, if any, on numerical solution procedure on the conclusions drawn. The present study has been further used for investigating the effects of input parameters (i.e. stiffness and mass of the system components, and impact velocity) on the computed results of transducers. Such an investigation can be beneficial in designing an impact testing set-up as well as transducers for recording impact responses. Next, the previous 3 DOF model representing the impact testing set-up has been extended to a 5 DOF model to show that additional refinement of the original 3 DOF model does not substantially alter the inferences drawn based on it. In the end, oscillations observed in computed load cell responses are analysed by computing natural frequencies for the 3 DOF lumped parameter model. To conclude the present study, a 2 DOF LPM of the given impact testing set-up with no load cell has been investigated and the frequency of oscillations in the accelerometer response is seen to increase corresponding to the mounting resonance frequency of the accelerometer. In order to explore the merits of alternative impact testing set-ups, LPMs have been formulated to idealize test configurations in which the load cell is arranged to come into direct contact with the specimen under impact, although the accelerometer is still mounted on the moving impactor head. One such arrangement is to have the load cell mounted stationary on the base under the specimen and another is to mount the load cell on the moving impactor head such that the load cell directly impacts the specimen. It is once again observed that both these models accurately reproduce the input load-displacement behaviour of the nonlinear spring corresponding to the tested component confirming the validity of the model. In contrast to the previous set-up which included a moving load cell not coming into contact with the specimen, the spring representing the load cell in these present cases yields a response that more closely matches the assumed input load-displacement response of a test specimen suggesting that the load cell coming into direct contact with the specimen can result in a more reliable measurement of the actual dynamic response. However, in practice, direct contact of the load cell with the specimen under impact loading is likely to damage the transducer, and hence needs to be mounted on the moving head, resulting in a loss of accuracy, which can be theoretically estimated and corrected by the methodology investigated in this work.

Cholesterol metabolism is critical for neuronal functions such as, myelin formation, neurotransmitters release, membrane repair and also synaptogenesis, in the Central Nervous System (CNS), and its homeostasis is mainly maintained by CYPX. This enzyme catalyses the conversion of cholesterol into X-Hydroxycholesterol (X-HC) and may be a useful marker of neurodegenerative diseases. The X-HC is able to cross the blood-brain-barrier (BBB) into the circulation, having possible roles in the overall bile acid synthesis in the liver, therefore having an indirect impact on intestinal microbiota within human Gastrointestinal tract (GI). In the other hand, a diet mainly rich in fat, carbohydrates and protein, a typical Western diet, have been highly associated with changes in the GI environment, promoting alterations in intestinal microbiota composition, termed as dysbiosis, being associated with early metabolic physiopathological changes, such as increased intestinal barrier permeability and a state of low-grade intestinal inflammation. The main objective of this study was to determine the effects of either Cyp overexpression and silencing treatment and diet on intestinal bacterial groups, cognitive abilities and also on colon health status. C57BL/J6 mice were fed with either chow diet or an High Fat Diet (HFD), for 12 weeks. To determine the effects caused by both Cyp overexpression and silencing and also by the HFD and Control diet on the intestinal bacteriome, the quantification of several intestinal bacterial groups was performed using qPCR. The targeted bacterial groups included Bacteroidetes, Firmicutes, Sulphate-Reducing Bacteria (SRB), Betaproteobacteria, Delta-and Gammaproteobacteria, Actinobacteria and Tenericutes. The exposure of mice to an HFD resulted in variations in the loads of the intestinal bacteria. Interestingly, the Cyp silencing lead to an approximation of intestinal bacterial loads between mice exposed to the different diets. The Cyp silencing resulted in a decreased performance in Y-maze spontaneous alternation test, within subjects with a chow diet. In addition, both Cyp overexpression and silencing in mice exposed to an HFD showed increased signs of intestinal inflammation. Taken together, this study showed that intestinal microbiota is mainly influenced by dietary factors.
Numa zona central do cérebro humano encontra-se o hipotálamo, sendo este constituído por quatros divisões principais, a área pré-ótica, hipotálamo anterior, hipotálamo tuberal e hipotálamo posterior. Sendo cada uma destas divisões constituída por diversos núcleos, desempenhando funções fundamentais para a manutenção da homeostasia do nosso organismo, tais como, termorregulação, controlo sobre o metabolismo energético, controlo sobre os estados de sono, respostas ao stress, crescimento, e também exerce o controlo sobre o nosso comportamento social, emocional, cognitivo e reprodutivo. Este pequeno órgão atua como uma central de comunicação entre o sistema nervoso central e a periferia, podendo regular vários órgãos periféricos como, a tiroide, o musculo, o osso e ainda o sistema gastrointestinal. A comunicação entre o sistema nervoso central e a periferia é essencialmente controlada pela barreira hematoencefálica, que para além de controlar a passagem de moléculas em ambos os sentidos, consoante as necessidades do organismo, também controla a entrada de toxinas e agentes patogénicos para o cérebro. Assim sendo, um bom funcionamento da barreira hematoencefálica é essencial tanto para o cérebro, como para os órgãos periféricos e, a sua disfunção, especialmente ao nível das “tight junctions”, resulta num aumento de permeabilidade da barreira, aumento de infiltração de células inflamatórias e ainda uma desregulação dos processos de transporte de nutrientes para ambos os sistemas, sendo estes eventos cada vez mais associados ao desenvolvimento de doenças neurodegenerativas, como também doenças ao nível metabólico, como por exemplo, a doença de Alzheimer ou Diabetes. O cérebro é o órgão mais rico em colesterol do corpo humano, contendo cerca de 23% do colesterol total existente no organismo, e ao contrário da zona periférica em que a homeostasia de colesterol é essencialmente dependente da dieta, a homeostasia de colesterol no cérebro parece ser maioritariamente realizada através de síntese de novo e reciclagem deste, a partir de acetilcoenzima A em astrócitos. Depois da sua síntese, o colesterol é conduzido até aos neurónios onde irá desempenhar funções a nível da formação de mielina, reparação da membrana, e ainda sinaptogênese. Diversos estudos têm sugerido que a acumulação de colesterol nos neurónios está associada a uma disfunção a nível cognitivo, sendo assim, este esterol tem sido associado a doenças neurodegenerativas, como a doença de Huntington ou a doença de Alzheimer. No entanto, apesar da sua importância, este composto não consegue atravessar a barreira hematoencefálica. Dentro da superfamília Citocromo P450, mais propriamente a proteína CYPx, está envolvida no metabolismo de colesterol no cérebro, e a sua ação reside na sua capacidade de converter colesterol a oxisterol, ao introduzir um oxigénio na cadeia altamente hidrofóbica do colesterol, sendo fulcral para a sua translocação através da barreira hematoencefálica. Foram reportadas evidências em que cerca de 90% do oxisterol resultante da ação de CYPx (X-HC), atravessa a barreira hematoencefálica para a circulação, onde será conduzido essencialmente para o fígado, onde é utilizado para a síntese de ácidos biliares. Atualmente, são sugeridas duas vias principais para síntese de ácidos biliares no fígado, a via Clássica e a via Alternativa. Resumidamente, a via clássica envolve a hidroxilação do colesterol catalisado pela enzima CYP7A1, contribuindo com cerca de 75% da síntese total de ácidos biliares, enquanto que a via alternativa é catalisada pela ação das enzimas CYP27A1 e CYP7B1, sendo posteriormente conjugados com glicina ou taurina, e armazenados na vesicula biliar. A formação de estruturas micelares por parte dos ácidos biliares, deve-se às suas características anfipáticas, o que facilita a emulsificação, absorção e digestão de lípidos e vitaminas insolúveis. Porém, os ácidos biliares secundários, metabolitos resultantes da atividade microbiana podem ser altamente tóxicos para o organismo, e os seus efeitos têm sido associados a doenças como o cancro do colon e reto. No intestino humano existe uma vasta e complexa comunidade de microrganismos, denominado de “Microbiota Intestinal”. Mantendo uma relação de simbiose, a microbiota intestinal confere diversas vantagens ao hospedeiro, nomeadamente a nível de maturação do sistema imune, proteção contra agentes patogénicos, manutenção da permeabilidade da barreira gastrointestinal, fermentação e absorção de carboidratos e, portanto, manter uma microbiota equilibrada, em eubiose, assegura uma boa função não só digestiva, como também a nível cerebral. Existem várias evidências que mostram uma comunicação bidirecional entre a microbiota gastrointestinal e cérebro, denominado de “microbiota-gut-brain axis”, assim sendo, a atividade da microbiota intestinal pode influenciar o nosso cérebro, e vice-versa. A via de comunicação entre estes sistemas ainda não está completamente compreendida, no entanto pensa-se que seja feita através do nervo Vago, Sistema Entérico nervoso e ainda através de metabolitos bacterianos. De entre todos os fatores que influenciam a microbiota intestinal, a dieta, é o fator que mais se destaca devido ao seu efeito notável. De facto, diversas publicações evidenciam um efeito negativo por parte de uma alimentação rica em gorduras, nomeadamente pela redução da diversidade microbiana no nosso intestino e ainda um aumento da permeabilidade da barreira gastrointestinal, possibilitando a passagem de endotoxinas e outros metabolitos bacterianos para a circulação, levando a um estado de inflamação intestinal de baixo grau. Para além disso, existem evidências que mostram que uma alimentação rica em gorduras pode levar a uma disfunção a nível cognitivo, e ainda a uma desregulação do metabolismo de ácidos biliares, caracterizado pelo aumento dos níveis que ácidos biliares em circulação, podendo ter efeitos a nível da microbiota intestinal. Este trabalho teve como principal objetivo analisar o efeito da sobre-expressão e silenciamento do gene Cyp, e de dois tipos de dieta, uma dieta controlo e uma dieta rica em gordura, na microbiota intestinal de ratinhos. Para além disso, os seus efeitos também foram analisados a nível cognitivo, bem como na inflamação intestinal. Foram selecionados 70 ratinhos da espécie C57BL/J6 que foram divididos em dois grupos. O primeiro grupo foi destinado à sobre-expressão deste gene, enquanto que o segundo grupo foi destinado ao estudo do silenciamento deste. As duas populações de ratinhos foram alimentadas com uma dieta controlo e uma dieta rica em gordura por 12 semanas. A intervenção a nível do hipotálamo (Cyp) teve lugar após as primeiras quatro semanas. A análise da composição da microbiota intestinal foi realizada a partir de amostras fecais, através de qPCR utilizando primers direcionados para diferentes grupos bacterianos, nomeadamente Bacteroidetes, Firmicutes, Bactérias Sulfato-Redutoras (BSR), Betaproteobacteria, Delta-e Gammaproteobacteria, Actinobacteria e Tenericutes. Através dos resultados obtidos da análise da composição da microbiota intestinal, no ensaio da sobre- expressão foi possível distinguir a microbiota intestinal de indivíduos que foram sujeitos a uma dieta controlo, daqueles que foram sujeitos a uma dieta rica em gorduras, o que indica que as suas variações se deveram maioritariamente ao tipo dieta a que foram sujeitos. No entanto, o silenciamento deste gene também mostrou exercer influência, levando a uma aproximação em termos da microbiota intestinal, entre indivíduos com diferentes dietas. A análise a nível cognitivo, utilizando o teste Y-Maze spontaneous alternations, indicou que contrariamente a estudos anteriores, uma alimentação rica em gorduras não afetou a memória a curto prazo dos ratinhos, no entanto, o silenciamento deste gene levou a uma diminuição da memória a curto prazo, em comparação com os ratinhos sujeitos à sobre-expressão. Por último, através da análise de cortes histológicos do intestino, foi possível verificar que, uma desregulação do metabolismo de colesterol no cérebro, bem como uma alimentação rica em gorduras, levou a uma maior ocorrência de inflamação intestinal.

Landscape transformation that occurred during the Middle Ages in western and central Europe is reflected in all pollen diagrams. An event that was so striking and widespread was used by Firbas to distinguish a biostratigraphical period called the Younger Subatlantic (zone X; Firbas 1949). High Medieval landscape transformation is connected with rapid colonization in our area that resulted in extensive deforestation and intensified agriculture. During the first half of the 13th century, the settlement network was already stabilized and was very similar to the current state and was reaching also mountain areas (Klápště 1994). New organization and changes in land ownership, as well as a need for more effective agriculture, resulted in the connecting of small fields into larger ones and in an increase of cultivated area (Klápště 2006). The use of the land was different, and for the first time complete (Bakels 2009). During a few centuries anthropogenic factors that were enormously enhanced throughout the 13th century, formed a cultural landscape that was much more similar to the landscape of today than to the landscape of, for instance, the 9th century. This doctoral thesis is focused on the Early Medieval landscape in the Czech lands and its transformation that culminated during the 13th and 14th...