Dissertations / Theses on the topic 'Tension Early'

While undoubtedly the historiography of witchcraft has undergone a renaissance in the past two decades, these developments have not always been speedy to filter down the regional incidents, especially in the instance of the Lancashire trials. Moreover, studies of this region have had a tendency to focus upon the two renowned trials of 1612 and 1633. The purpose of this study is to provide a more extensive and inclusive study of allegedly supernatural incidents in this region, which acknowledges historiographical progression. In the process a multitude of incidents and individuals which have been neglected will be assessed, such as the 'blesser' Mary Shawe, the dispossession of Richard Dugdale et al. In doing so not only will much be revealed about the evolution of beliefs regarding the supernatural in the local community, but also how they were interpreted and manipulated nationally, and in the process both reflected and made significant contributions to politico-religious debates

In recent years, the increasingly precise constraints on the value of the Hubble constant, H0, have highlighted a discrepancy between the results arising from early-time and late-time measurements. A potential solution to this so-called Hubble tension is the hypothesis that we reside in a cosmic void, i.e. an underdense cosmic neighbourhood characterized by a faster local expansion rate. In this thesis, we model this scenario through the Lemaître-Tolman-Bondi formalism for an isotropic but inhomogeneous universe containing matter, curvature and a cosmological constant, which we denote by ΛLTB. We numerically implement this framework with two different formulations for the local matter density profile, respectively based upon a more realistic Gaussian ansatz and the idealized scenario of the so-called Oppenheimer-Snyder model. We then constrain the background cosmology and the void parameters involved in each case through a Markov Chain Monte Carlo analysis with a combination of recent data sets: the Pantheon Sample of type Ia supernovae, a collection of baryon acoustic oscillations data points from different galaxy surveys and the distance priors extracted from the latest Planck data release. For both models, the resulting bounds on the investigated parameter space suggest a preference for a -13% density drop with a size of approximately 300 Mpc, interestingly matching the prediction for the so-called KBC void already identified on the basis of independent analyses using galaxy distributions. We quantify the level of improvement on the Hubble tension by analyzing the ΛLTB constraints on the B-band absolute magnitude of the supernovae, which provides the calibration for the local measurements of H0. Since no significant difference is observed with respect to an analogous fit performed with the standard ΛCDM model, we conclude that the potential presence of a local void does not resolve the tension.

In the mammalian embryo, between 3.5 and 4.5 days after fertilisation, the cells of the inner cell mass evolve from a uniform aggregate to an ordered structure with two distinct tissue layers - the primitive endoderm and epiblast. It was originally assumed that cells differentiated to form these layers in situ, but more recent evidence suggests that both cell types arise scattered throughout the inner cell mass, and it is thus proposed that the tissue layers self-organise by physical mechanisms after the specification of the two cell types. We have developed a computational model based on the subcellular element method to combine theoretical and experimental work and elucidate the mechanisms that drive this self-organisation. The subcellular element method models each cell as a cloud of infinitesimal points that interact with their nearest neighbours by local forces. Our method is built around the introduction of a tensile cortex in each cell by identifying boundary elements and using a Delaunay triangulation to define a network of forces that act within this boundary layer. Once the cortex has been established, we allow the tension in the network to vary locally at interfaces, modelling the exclusion of myosin at cell-cell interfaces and consequent reduction in tension. The model is validated by testing the simulated interfaces in cell doublets and comparing to experimental data and previous theoretical work. Furthermore, we introduce dynamic tension to model blebbing in primitive endoderm cells. We investigate the effects of cortical tension, differential interfacial tension, and blebbing on interfaces, rearrangement, and sorting. By establishing quantitative measurements of sorting we produce phase diagrams of sorting magnitude given system parameters and find that robust sorting in a 30 cell aggregate is best achieved by a combination of differential interfacial tension and blebbing.

The purpose of this study was to analyze the ways in which 19th century Gothic fiction novelists Charles Brockden Brow and James Hogg explore the themes of religious enthusiasm and divine revelation. A close look at these texts reveals a common interest in the tension between the imagination and reality. By analyzing the philosophical and theological roots of these issues it becomes clear that Wieland and Confessions of a Justified Sinner mirror the anxieties of 19th century Anglo American culture. Questions regarding voice and authority, the importance of testimony, and religious seduction are common to both novels. I maintain that these authors comment on the obscure nature of human rationale by presenting readers with narrators that exhibit traits of delusion and spiritual awakening.

This study approaches wood quality in young trees by very early screening – and consequent selection for propagation – on the basis of physical and mechanical properties. In chapter 1 corewood properties are reviewed and the importance and problems associated with early screening are discussed. Due to randomly distributed reaction wood in young trees it is advantageous to lean trees to avoid intermixing of the two wood types and minimise any uncertainty in the results. In chapter 2 physical and mechanical properties are described for opposite and compression wood in a population of Pinus radiata comprising of 50 families, at a young (<3 years) age. The dynamic stiffness was determined using the resonance acoustic technique. Density was measured using water displacement method, and longitudinal and volumetric shrinkage were measured from green to ~5% moisture content. The compression wood and opposite wood differ significantly in all the measured properties. Compression wood was characterised by high density and high longitudinal shrinkage. The mean stiffness of opposite wood was 3.0 GPa with a mean standard deviation of 0.39, and the mean longitudinal shrinkage of opposite wood was 0.99% with mean standard deviation of 0.31 across the samples examined. This variation in stiffness and longitudinal shrinkage in opposite wood can be exploited to screen for wood quality. The variation in stiffness and longitudinal shrinkage within a family was comparable to variation among families. In spite of large within site variability it was possible to distinguish between the worst and the best families in opposite wood at young age. In chapter 3 ranking of selected families of Pinus radiata was done based on microfibril angle, which is considered as the main factor influencing both stiffness and longitudinal shrinkage. The ranking was compared with ranking done using acoustic velocity which is more practical and fast method of screening trees. The mean MFA in opposite wood was 39° with a mean standard deviation of 3.7 and in compression wood the mean MFA was 44° with a mean standard deviation of 2.9. The variation in MFA in opposite wood offers opportunities to breed for trees with low MFA. A strong negative correlation (R=-0.68) between acoustic velocity squared and MFA in opposite wood suggested that the resonance technique can be used effectively to screen very young wood rather than using MFA. At high MFA, the cell wall matrix also plays an important role in determining the mechanical and physical properties of the wood. At present the chemical composition of wood samples is determined by wet chemical analysis, which is time consuming and laborious. Therefore, it is impractical to characterise large numbers of samples. Mechanical properties, particularly tanδ (dissipation of energy), which changes with temperature and frequency as the structure of the material changes at the molecular level, was studied using dynamic mechanical analysis (DMA). The idea was to assess if it can be used as a quality trait for tree screening instead of wet chemical analysis. Compression wood and opposite wood were characterised for storage modulus and tanδ at constant moisture content. In practice the instrument used, TA instrument Q800, was unable to provide the desired range of temperature and humidity so no glass transition at 9% moisture content in the temperature range of 10°C to 85°C at 1 and 10 Hz frequency was observed that might be attributed to the hemicelluloses (or lignin). In spite of the huge difference in chemical composition of opposite and compression wood, the difference in their mean tanδ at 25°C and 1 Hz values was just 7%. The positive correlation between MFA and tanδ in opposite wood suggested that MFA also plays a role in the dissipation of energy. The strong relationship between storage modulus and dynamic modulus (R=0.74) again justifies the reliability of resonance technique to screen young wood for stiffness. Concurrently eighty seven, two-year-old leant Eucalyptus regnans were studied for growth strains along with other physical and mechanical properties, independently in tension and opposite wood. The leant trees in Eucalyptus regnans vary in their average growth strain. Strong correlation between measured and calculated strain (R=0.93) suggests that the quick split method can be used to screen large populations for growth stresses. Tension wood was characterised by high density and was three times stiffer than opposite wood and twice as high in volumetric shrinkage. The high longitudinal shrinkage in opposite wood could be due to comparatively high MFAs in opposite wood of the young trees. There was no correlation between growth strain values and other measured properties in opposite wood. It is possible to screen for growth strain at age two, without any adverse effect on stiffness and shrinkage properties.

Abstract The purposes of the present research were to compare the outcome after Achilles tendon rupture repair in two postoperative regimens, to compare Achilles tendon elongation in two postoperative treatment methods, to compare the effects of two postoperative methods on motor performance aspects such as simple reaction time, choice reaction time, speed of movement, foot tapping speed and coordination, to test the mechanical properties of the recently developed poly-L/D-lactide (PLDLA) sutures and Maxon® sutures when implanted in the Achilles tendons of rabbits, and to study the histological tissue reactions and biodegradation of these sutures under the same conditions. Isokinetic calf muscle strength scores at the last control check-up were excellent in 56% of the patients in the early motion group, good in 32%, fair in 8%, and poor in 4%, whereas the scores in the cast group were excellent in 29% of cases, good in 50% and fair in 21%. The ankle performance scores were excellent or good in 88% of the patients in the early motion group, fair in 4% and poor in 8%, whereas the scores in the cast group were excellent or good in 92% of cases and fair in 8%. No significant differences were seen between the two groups at 3 months and at the last control checkups with regard to pain, stiffness, subjective calf muscle weakness, footwear restrictions, range of ankle motion, isokinetic calf muscle strength or overall outcome. The complications included 1 re-rupture in the early motion group and 1 deep infection and 2 re-ruptures in the cast group. AT elongation occurred in both groups, but was somewhat less marked in the early motion group. The AT elongation curves rose at first and then fell slowly in both groups. The patients who had less AT elongation achieved a better clinical outcome. AT elongation did not correlate significantly with age, body mass index or isokinetic peak torques. The recovery of motor performance functions such as simple reaction time, choice reaction time, speed of movement, foot tapping speed and coordination did not depend on the two postoperative regimens. The motor functions of the operated leg had obviously recovered to the level of the non-operated leg 12 weeks after the operation. Sutures made of PLDLA were used successfully for Achilles tendon repair in rabbits. There was no significant difference between the in vitro and in vivo tensile strength retention of the sutures. By comparison with Maxon®, PLDLA was found to have a lower initial tensile strength but more prolonged strength retention. The breaking strength values of the Achilles tendons repaired with sutures of these types were not significantly different at 6 weeks. Intratendinous PLDLA sutures formed a thinner fibrous capsule during the 12-week follow-up period than did Maxon® sutures of the same diameter. The suture materials had not been totally absorbed by 12 weeks.

Paradoxe de la prolepse : en dévoilant par avance un événement de l’histoire, elle risque de ruiner le suspens ; en n’évoquant qu’allusivement ce qui va suivre, elle peut au contraire y contribuer. Le traitement des anticipations a toujours été au cœur des débats sur la tension narrative. L’examen de poétiques et de rhétoriques antiques et classiques, leur confrontation avec les théories contemporaines permettent de retracer la longue histoire d’un procédé à travers les discours contradictoires qui l’ont défini.Lisons les romans de l’Ancien Régime, nous verrons ce paradoxe en action. Au seuil du XVIIe siècle, la prolepse appartient, comme le début in medias res, à la panoplie des artifices visant à maintenir suspendu l’esprit du lecteur et à structurer de grandes machines romanesques ; au siècle suivant, les pseudo-mémorialistes, tout en puisant dans ce fonds, la posent comme le symptôme d’une écriture naturelle, désordonnée, parfois défaite, peu soucieuse de suspens et d’architecture, bref, la marque par excellence d’une écriture du cœur.Tout se joue dans l’appréhension progressive du texte par le lecteur et l’interprétation de la voix narratoriale supposée le guider. Les outils de la narratologie sont réexaminés et affinés pour que puisse être pris en considération le cheminement pas à pas du lecteur ; afin d’étudier des unités plus petites ou des manœuvres narratives particulièrement subtiles, il faut combiner ces outils avec les instruments de la linguistique énonciative (reprises anaphoriques et annonces cataphoriques, usages des temps verbaux, phénomènes polyphoniques liés à la régie narrative). On évalue ainsi la manière dont, au long d’un siècle et demi d’une production romanesque très diversifiée, sont suscitées des attentes, souvent comblées, parfois frustrées : si l’anticipation est d’ordinaire un moment où une voix de régie organise le texte, il arrive en effet que ce procédé provoque des dérèglements dont nous pouvons, critiques embarrassés ou lecteurs amusés, suivre les aléas
There is a paradox of prolepsis : because it tells in advance an event of the story, it runs the risk of ruining suspense ; because it only evokes this event allusively, it may, on the contrary, help to create suspense. The use of anticipation has always been at the core of the debate on narrative tension. Through the study of ancient and classical poetics and rhetorics, brought in comparison with contemporary theories, this work seeks to retrace the long history of a highly controversial narrative device.Reading the novels of the Ancien Régime, one may see this paradox at work. At the dawn of the seventeenth-century, prolepses belong, along with in medias res openings, to the repertoire of artificial contrivances used in the building of huge novelistic machines, as they keep the reader’s mind suspended ; in the first half of the following century, the Memoir-Novel uses the very same device to establish a new manner of writing : prolepses become the sign of an unsophisticated prose, attuned to the effusions of the heart.At stake here is the reader’s progressive apprehension of the text and the way he interprets the narratorial voice. Narratological tools are re-examined and refined so as to take into consideration the act of reading and its dynamics ; elements of enunciative linguistics are used for the study of small textual units and subtle narrative manipulations. Through this overview of one hundred and fifty years of prose fiction, we trace the different manners in which expectations are aroused, usually fulfilled, and exceptionally frustrated

Ce travail est une contribution à l'étude du transistor bipolaire hyperfréquence sur puce de silicium. Il présente tout d’abord deux méthodes originales permettant de réduire la Capacité extrinsèque Base-Collecteur, d'augmenter la tension de claquage Base-Collecteur, d'augmenter la tension Early VA, d'augmenter le gain en puissance maximal Gpmax et d'augmenter la fréquence de transition FT. Il présente ensuite un nouveau transistor, de structure hybride entre le NPN vertical et le NPN latéral, baptisé bipolaire-CLEV (à Collecteur Latéral-Emetteur Vertical). Ce travail est généralisable à d'autres technologies de transistors hyperfréquences telles que les transistors à substrats III-V ou les transistors à hétérojonctions
This work is a contribution to the study of the high-speed bipolar transistor on silicon chip. First, it presents two original methods allowing to reduce the Base-Collector extrinsic Capacitance, to increase the Base-Collector breakdown voltage, to increase the Voltage Early VA, to increase the maximum power gain Gpmax and to increase the transition frequency FT. Then, it presents a new transistor, hybrid structure between the vertical NPN and the lateral NPN, named bipolar-CLEV (lateral collector-vertical emitter). This study can be generalized to other high speed transistor technologies such as III-V substrate transistors or heterojunction transistors

Ce travail est une contribution à l'étude du transistor bipolaire hyperfréquence sur puce de silicium. Il présente tout d’abord deux méthodes originales permettant de réduire la Capacité extrinsèque Base-Collecteur, d'augmenter la tension de claquage Base-Collecteur, d'augmenter la tension Early VA, d'augmenter le gain en puissance maximal Gpmax et d'augmenter la fréquence de transition FT. Il présente ensuite un nouveau transistor, de structure hybride entre le NPN vertical et le NPN latéral, baptisé bipolaire-CLEV (à Collecteur Latéral-Emetteur Vertical). Ce travail est généralisable à d'autres technologies de transistors hyperfréquences telles que les transistors à substrats III-V ou les transistors à hétérojonctions
This work is a contribution to the study of the high-speed bipolar transistor on silicon chip. First, it presents two original methods allowing to reduce the Base-Collector extrinsic Capacitance, to increase the Base-Collector breakdown voltage, to increase the Voltage Early VA, to increase the maximum power gain Gpmax and to increase the transition frequency FT. Then, it presents a new transistor, hybrid structure between the vertical NPN and the lateral NPN, named bipolar-CLEV (lateral collector-vertical emitter). This study can be generalized to other high speed transistor technologies such as III-V substrate transistors or heterojunction transistors

This dissertation was aimed at providing information on developing and sustaining public-private partnerships (PPPs) in early childhood education as a way to increase efficiency and effectiveness on how resources are allocated. This study also emphasizes how teachers are perceived and supported within the PPP context. Studies have shown that investing in early childhood education yields the greatest gains to one's life and society at large. Yet, the early childhood field continues to battle waves of budget cuts while striving to convince policymakers and the public that early education is critical and necessary.

Although PPP presents itself as a new way of doing business by combining resources from the public and private sectors and redistributed based on the shared goal and vision of the PPP, there is limited research on PPPs and even more scarce specifically related to early childhood. The goal of this study is to provide exposure to the early childhood field on how PPPs can be formed and sustained using the Educare model as one example of a PPP in early childhood.

This was a qualitative designed to capture rich conversations and experiences of research participants that are relevant and appropriate to the early childhood field. Grounded theory was used in this study to learn from research participants' perceptions of PPPs based on their experience and expertise in PPP and early childhood education.

This study used theoretical sampling to target research participants at a specific Educare development site to capture real time and real life experiences in developing a PPP in early childhood education. The Educare model was developed by the Ounce of Prevention Fund in 2000 aimed at "narrow[ing] the achievement gap for students in high-risk communities" (Ounce of Prevention, Educare schools, 2011). The Educare model has set requirements for teachers and all related job categories that will work in an Educare school including professional development requirements. The Educare school also has a salary structure that is competitive to the local public elementary schools.

Five themes were identified in the findings and discussed in relation to the significance of this study. The findings from this study have implications for early childhood administrators, educators, funders, advocates, and the field at large on maximizing the usage of existing resources. The findings from this study, including questions raised, are significant in development of partnerships in early childhood education.

Thesis (MEng)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The early age cracking of concrete, which includes plastic shrinkage cracking (PShC) and plastic settlement cracking (PSeC), commonly occurs in flat concrete elements such as bridge decks and slabs or at the change of a concrete section depth. These cracks typically occur once the concrete has been cast and consolidated up to the final setting time, and initiate when the tensile stresses developed in the concrete exceeds its ultimate tensile strength or, alternatively phrased, when the restrained shrinkage induced strain in the concrete exceeds its tensile strain capacity. These cracks have a premature detrimental effect on the durability and strength of concrete structures as they allow deleterious materials to penetrate the concrete, which could cause the corrosion of steel reinforcing. With this in mind, the objective of this study is to gain a fundamental understanding of the tensile properties of early age concrete, up to the point of final setting, as well as the variables that affect these properties. This is done to better understand, and ultimately reduce the risk of early age cracking. To achieve this, experimental assemblies found in literature were evaluated and built upon to create a multi-component uniaxial tensile testing setup that is able to capture the complete stress-strain behaviour of early age concrete, while still in a plastic state. The following significant findings were attained from this study: • Reducing the coarse aggregate size in a concrete mix increases both the tensile strength and Young’s modulus of early age concrete, while reducing both its fracture energy and fracture process zone (FPZ) characteristic length. • The low volume addition of microfibres to a conventional concrete mix increases both the fracture energy and the FPZ characteristic length of early age concrete. • The low volume addition of microfibres to a conventional concrete mix increases the strain capacity of early age concrete shortly before and after the initial setting time. This increased strain capacity is believed to be of great significance for the prevention of PShC. • The addition of an accelerator to a conventional concrete mix accelerates the development of the tensile properties of early age concrete, while a retarder reduces it. • The addition of a retarder to a conventional concrete mix increases the strain capacity of early age concrete shortly before and after the initial setting time. This provides a reason for the reduced PShC severity observed in retarded mixes in certain instances. From this study it is concluded that the results from the tensile tests provide a greater understanding of the tensile properties of early age concrete as well as the variables that affect them. When interpreting these results in combination with those obtained from PShC experiments, it is suggested that it is possible to determine when and if PShC will occur.
AFRIKAANSE OPSOMMING: Die vroëe-ouderdom kraking van beton, wat plastiese krimp krake (PKK) en plastiese versakkings krake (PVK) insluit, kom algemeen voor in plat betonelemente soos brug-dekke en blaaie, of by die die verandering in die deursnit diepte van betonelemente. Die krake kom tiepies voor vandat beton gegiet en gekompakteer is totdat dit die finale settyd bereik, en vind plaas sodra die trekspanning wat in die beton ontstaan sy treksterkte oorskry of, anders bewoord, wanneer die verhinderde krimp geinduseerde vervorming van die beton, die vervormings-kapasiteit van die beton oorskry. Hierdie krake het ʼn voortydige nagelige uitwerking op die duursaamheid en sterkte van betonstrukture aangesien hulle toelaat dat skadelike stowwe die beton binnedring, wat die korrosie van staalbewapening veroorsaak. Met dit ingedagte is die doel van die studie om fundamentele kennis rakende die vroëe-ouderdom trekeienskappe van beton, tot by die punt van finale set, asook die veranderlikes wat die eienskappe beinvloed, te verwerf. Om vroëe-ouederdom krake beter te verstaan en uiteindelik, te voorkom, is hierdie kennis nodig. Eksperimentele opstellings in literatuur is ge-evalueer en op voortgebou vir die bou van ʼn multi-komponet eenassige terktoetsopstelling om die volledige spanning-vervorming gedrag van vroëe-ouderdom beton vas te vang. Die volgende bevindings het uit die studie aan die lig gekom: • ʼn Kleiner aggregaat grootte in n betonmeng verhoog beide die trekstrekte en Young se modulus van vroëe-ouderdom beton, terwyl dit beide die fraktuur-energie en die fraktuur proses sone (FPS) se karakteristieke lengte verminder. • Die lae volume byvoeging van mikrovesels tot ʼn betonmeng verhoog beide die fraktuur-energie en die FPS se karakteristieke lengte van vroëe-ouderdom beton. • Die lae volume byvoeging van mikrovesels tot ʼn betonmeng verhoog die vervormings kapasiteit van vroëe-ouderdom beton kort voor en na die aanvanklike settyd. Daar word geglo dat hierdie verhoogde vervormings-kapasiteit van groot belang is vir die voorkoming van PKK. • Die byvoeging van ʼn versneller tot ʼn betonmeng versnel die ontwikkelingstempo van die trekeienskappe van vroëe-ouderdom beton, terwyl ʼn vertrager dit verlaag. • Die byvoeging van ʼn vertrager tot ʼn betonmeng verhoog die vervormings-kapasiteit van vroëe-ouderdom beton kort voor en na die aanvanklike settyd. Dit verskaf die rede vir die bevinding dat die byvoeging van ʼn vertrager PKK in sekere gevalle verminder. Hierdie studie het bevind dat die die trektoetse ʼn groter begrip rakende die trek-eienskappe van vroëe-ouderdom beton, en die veranderlikes wat die eienskappe beinvloed, gelewer het. Wanneer die resultate van die studie tesame met PShC toetse geinterpreteer word, will dit voorkom dat dit moontlik is om te bepaal wanneer, en of PKK sal plaasvind.

This dissertation seeks to clarify the moral and political shape of economic exchange with an intellectual history of capitalism at its eighteenth-century inception. It seeks to avoid the familiar polarities of Marxist and capitalist economic ideologies by framing the ethical questions of economic exchange in historical terms: Why does the modern economic order seem to create moral contradictions and undermine political institutions? In response to this question, the thesis recovers the contributions of the Scottish historian and moral philosopher, Adam Ferguson (1723- 1816). Because modern economy had not yet taken on its modern abstraction and was still a thinkable reality, Ferguson’s treatment on history, action, and political institutions provide a fertile starting point for envisaging a distinctly moral configuration of the economic sphere. He prepares ground for a critical assessment of the political and economic relationship by criticizing the ideal of progress and emphasizing the need for dignified human exertion. His claim is that the liberalized marketplace undermines political institutions—especially law—to the extent that is leaves a people enslaved both to their own dependencies, as well as to other nations for whom commercial luxury is not a vice. My argument carries Ferguson’s claim forward by asserting that the Market itself now tyrannizes and enslaves in much the way Ferguson imagined a military despot would tyrannize unprepared societies of the eighteenth-century. Eighteenth-century theology is, in many respects, a period of relative theological austerity; so it is therefore unsurprising that a morally confused political instrument (capitalism) would emerge in an age largely devoid of theological imagination or conscience. Jesus Christ is no longer the origin, end, or meaning of history; co-creation is no longer the principal object of human action or labour; and the means of Christ’s rule through the political order are rejected in favour of luxuries and conveniences of modern commerce. The marketplace now embodies all the fears eighteenth-century theorists reserved for despots, tyrannizing western societies and threatening the resolve of already fractured political institutions.

This project explores connections between hero and history, text and context. By engaging Postcolonial theories about the roles that invasion and oppression, play in developing national identity and how colonized people respond to such encounters in literature, I examine how experiences of invasion and hostile interaction as represented in medieval and early modern English literature influenced the creation of specific heroic values. In my first chapter, I analyze The Battle of Maldon and Beowulf as exemplars of the Anglo-Saxon culture, observing that Byrhtnoth and Beowulf work as fictional embodiments of a fantasy of power: men of super-human strength and exceptional resoluteness who, through remarkable sacrifices, inspire men to accomplish phenomenal deeds of their own. Next, I explore Arthur in The Alliterative Morte Arthure and Le Morte Darthur, who embraces his hybridity, fluidly moving between the Anglo-Saxon warrior tradition and the French romance tradition. Last, I consider Shakespeare’s Henry V, which depicts a conquering hero who possesses the prowess and nobility of his heroic predecessors and the ability to succeed where they failed, securing England’s continental dominance. In each era, I contend that the authors created heroes on whom they could project a fantasized identity which defied the realities of their time, heroes who changed based upon the type of threat faced by England. This study samples five hundred years of literature and uses this breadth to explore cross-periodic continuity, finding that the heroes of these texts respond not only to their historical context, but also to each other. This scope allows one to see how the emblem of the hero responds to the reality of the authors and audiences of these texts. The figure of the hero develops over centuries, demonstrating that as the needs of the authors and audiences change, so, too, does the character who represents them. These literary figures provide a unique window into the culture and concerns of the authors and audiences during the medieval and early modern eras. They represent desire for strength, inspiration, glory and triumph. They reflect the agony of anxiety, vulnerability, defeat, and hopelessness. Most importantly, they reimagine, reframe, and redress reality.

This dissertation concerns the development of a new interorganizational vehicle platform in the truck industry. The studied project setting was large, and can be referred to as a mega project. I ask the question How are boundaries organized in an interorganizational vehicle platform project setting, and how can we understand the tensions which arise when such organizing is performed? I assume that tensions arise in relation to questions concerning novelty, interdependencies, and differences.  Tensions should therefore not be seen as something bad, tensions are rather a prerequisite for achieving change.   The overall aim is to create insights in how boundaries in an interorganizational platform project setting are organized between: projects and governing actors, projects and permanent organizations, projects and external organizations, projects and projects, and finally inside projects (between different functions).  A secondary aim is to understand the roles which actors, activities and objects play, and the tensions which are experienced, when boundaries are being challenged and organized.   The study was performed during the concept phase, and a practice approach was used in order to capture the inner life of projects. A project setting with three projects was studied for three months, where I performed 68 interviews and observed 32 meetings. I have used a mix of narrative and alternate templates strategies and induced themes which constitute the base for the analysis.   I assume that boundaries are socially constructed and I argue that traditional normative findings in project management studies should be complemented with findings from organizational theory, and therefore use a multidisciplinary theoretical base. I have combined theories relating to; boundary construction, projects, boundary actors, activities, objects, and coordination/integration.   My analysis consists of two parts, in the first part I analyze value-, mandate-, and structural tensions and finds that actors in the setting; organize a commonality balancing area where decisions are affected by a mandates filter and need to be understood in relation to a coopetitive tensions model. In the second part of the analysis I have found that actors in the setting balance tensions and organize boundaries by performing four major Quality improvement loops based on a fragmented value base where boundary activities should be seen as having three dimensions; administrative, sharing, and political.   The creation of the shared platform is simultaneously affected by strategic, operational, and functional efforts.  This fact in combination with the size and uniqueness of the project setting, leads to the insight that technological innovation must be accompanied by organizational innovation. Therefore I have suggested that organizing of boundaries in interorganizational vehicle project settings should be understood as being performed through Concurrent Boundary Enactment.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica
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Este trabalho apresenta um modelo compacto para a tensão de Early do transistor MOS em inversão fraca e moderada. Utilizando as equações do modelo ACM (Advanced Compact Mosfet Model) e incluindo os efeitos de canal curto relevantes como o DIBL e a modulação do comprimento das zonas de depleção de dreno e fonte, chega-se a um modelo compacto para a tensão de Early que proporciona aproximações úteis para o projetista de circuitos integrados. Para extração de parâmetros do modelo proposto foram feitas medidas experimentais em transistores de diversos comprimentos, níveis de inversão e tensões de dreno. As curvas traçadas de acordo com o modelo compacto e com parâmetros extraídos para dispositivos em tecnologia CMOS 0,35 m são comparadas às curvas experimentais. Os resultados obtidos comprovam a eficiência do modelo como uma aproximação para cálculos de primeira ordem.

L'obbiettivo di questa tesi è lo studio delle fluttuazioni quantistiche dei modi tensoriali primordiali prodotti durante l'inflazione, con particolare attenzione alla possibilità di rilevare tali modi come onde gravitazionali di background. Una eventuale rilevazione confermerebbe ulteriormente la validità dei modelli inflazionari. Tuttavia, la densità di energia predetta per le onde gravitazionali di background è di gran lunga inferiore alla sensibilità degli attuali rivelatori. In questo lavoro noi andiamo oltre l'inflazione slow-roll standard e analizziamo nuovi modelli che ci permettono di amplificare le perturbazioni tensoriali su scale al di fuori dell'orizzonte. Introduciamo un meccanismo che sfrutta una fase transitoria di evoluzione non-attractor per amplificare i modi tensoriali. Procediamo poi con lo studio della fenomenologia del modello, dimostrando la possibilità di amplificare la densità di energia delle onde gravitazionali fino alle scale accessibili dai rivelatori LISA, aLIGO e PTA. Calcoliamo poi il numero di e-folds di fase non-attractor necessari per assicurare la rivelazione di tali onde. Successivamente, presentiamo un nuovo modello di bigravità, caratterizzato da un termine di accoppiamento tra un tensore privo di massa ed uno massivo. Presentiamo un'analisi dettagliata della dinamica dei due campi tensoriali, derivando vincoli che la massa del campo deve soddisfare per poter amplificare le fluttuazioni prive di massa. Infine, assumiamo che l'accoppiamento sia dominante per un certo numero di e-folds durante l'inflazione e diamo una stima di tale valore per i tre rivelatori sopracitati.

Schizophrenia is a severe mental illness that affects approximately 1% of the population worldwide, and which typically has a devastating effect on the lives of its sufferers. The characteristic symptoms of the disease include hallucinations, delusions, disorganized thought and reduced emotional expression. While many of the early theories of schizophrenia focused on its psychosocial foundations, more recent theories have focused on the neurobiological underpinnings of the disease. This thesis has four primary aims: 1) to use magnetic resonance imaging (MRI) to identify the structural brain abnormalities present in patients suffering from their first episode of schizophrenia (FES), 2) to elucidate whether these abnormalities were static or progressive over the first 2-3 years of patients’ illness, 3) to identify the relationship between these neuroanatomical abnormalities and patients’ clinical profile, and 4) to identify the normative relationship between longitudinal changes in neuroanatomy and electrophysiology in healthy participants, and to compare this to the relationship observed between these two indices in patients with FES. The aim of Chapter 2 was to use MRI to identify the neuroanatomical changes that occur over adolescence in healthy participants, and to identify the normative relationship between the neuroanatomical changes and electrophysiological changes associated with healthy periadolescent brain maturation. MRI and electroencephalographic (EEG) scans were acquired from 138 healthy participants between the ages of 10 and 30 years. The MRI scans were segmented into grey matter (GM) and white matter (WM) images, before being parcellated into the frontal, temporal, parietal and occipital lobes. Absolute EEG power was calculated for the slow-wave, alpha and beta frequency bands, for the corresponding cortical regions. The age-related changes in regional tissue volumes and regional EEG power were inferred with a regression model. The results indicated that the healthy participants experienced accelerated GM loss, EEG power loss and WM gain in the frontal and parietal lobes between the ages of 10 and 20 years, which decelerated between the ages of 20 and 30 years. A linear relationship was also observed between the maturational changes in regional GM volumes and EEG power in the frontal and parietal lobes. These results indicate that the periadolescent period is a time of great structural and electrophysiological change in the healthy human brain. The aim of Chapter 3 was to identify the GM abnormalities present in patients with FES, both at the time of their first presentation to mental health services (baseline), and over the first 2-3 years of their illness (follow-up). MRI scans were acquired from 41 patients with FES at baseline, and 47 matched healthy control subjects. Of these participants, 25 FES patients and 26 controls returned 2-3 years later for a follow-up scan. The analysis technique of voxel-based morphometry (VBM) was used in conjunction with the Statistical Parametric Mapping (SPM) software package in order to identify the regions of GM difference between the groups at baseline. The related analysis technique of tensor-based morphometry (TBM) was used to identify subjects’ longitudinal GM change over the follow-up interval. Relative to the healthy controls, the FES patients were observed to exhibit widespread GM reductions in the frontal, parietal and temporal cortices and cerebellum at baseline, as well as more circumscribed regions of GM increase, particularly in the occipital lobe. Furthermore, the FES patients lost considerably more GM over the follow-up interval than the controls, particularly in the parietal and temporal cortices. These results indicate that patients with FES exhibit significant structural brain abnormalities very early in the course of their illness, and that these abnormalities progress over the first few years of their illness. Chapter 4 employed the same methodology to investigate the white matter abnormalities exhibited by the FES subjects relative to the controls, both at baseline and over the follow-up interval. Compared to controls, the FES patients exhibited volumetric WM deficits in the frontal and temporal lobes at baseline, as well as volumetric increases at the fronto-parietal junction bilaterally. Furthermore, the FES patients lost considerably more WM over the follow-up interval than did the controls in the middle and inferior temporal cortex bilaterally. While there is substantial evidence indicating that abnormalities in the maturational processes of myelination play a significant role in the development of WM abnormalities in FES, the observed longitudinal reductions in WM were consistent with the death of a select population of temporal lobe neurons over the follow-up interval. The aim of Chapter 5 was to investigate the clinical correlates of the GM abnormalities exhibited by the FES patients at baseline. The volumes of four distinct cerebral regions where 31 patients with FES exhibited reduced GM volumes relative to 30 matched controls were calculated and correlated with patients’ scores on three primary symptom dimensions: Disorganization, Reality Distortion and Psychomotor Poverty. The results indicated that the greater the degree of atrophy exhibited by the FES patients in three of these four ‘regions-of-reduction’, the less severe their degree of Reality Distortion. These results suggest that an excessive amount of GM atrophy may in fact preclude the formation of hallucinations or highly systematized delusions in patients with FES. The aim of Chapter 6 was to identify the relationship between the longitudinal changes in brain structure and brain electrophysiology exhibited by 19 FES patients over the first 2-3 years of their illness, and to compare it to the normative relationship between the two indices reported in Chapter 2. The methodology employed for the parcellation of the MRI and EEG data was identical to Chapter 2. The results indicated that, in contrast to the healthy controls, the longitudinal reduction in GM volume exhibited by the FES patients was not associated with a corresponding reduction in EEG power in any brain lobe. In contrast, EEG power was observed to be maintained or even to increase over the follow-up interval in these patients. These results were consistent with the FES patients experiencing an abnormal elevation of neural synchrony. Such an abnormality in neural synchrony could potentially form the basis of the dysfunctional neural connectivity that has been widely proposed to underlie the functional deficits present in patients with schizophrenia. The primary aim of Chapter 7 was to assimilate the findings from the preceding empirical chapters with the theoretical framework provided in the literature, into an integrated and testable model of schizophrenia. The model emphasized dysfunctions in brain maturation, specifically in the normative processes of synaptic ‘pruning’ and axonal myelination, as playing a key role in the development of disintegrated neural activity and the subsequent onset of schizophrenic symptoms. The model concluded with the novel proposal that disintegrated neural activity arises from abnormal elevations in the synchrony of synaptic activity in patients with first-episode schizophrenia.

Doctor of Philosophy (PhD)
Schizophrenia is a severe mental illness that affects approximately 1% of the population worldwide, and which typically has a devastating effect on the lives of its sufferers. The characteristic symptoms of the disease include hallucinations, delusions, disorganized thought and reduced emotional expression. While many of the early theories of schizophrenia focused on its psychosocial foundations, more recent theories have focused on the neurobiological underpinnings of the disease. This thesis has four primary aims: 1) to use magnetic resonance imaging (MRI) to identify the structural brain abnormalities present in patients suffering from their first episode of schizophrenia (FES), 2) to elucidate whether these abnormalities were static or progressive over the first 2-3 years of patients’ illness, 3) to identify the relationship between these neuroanatomical abnormalities and patients’ clinical profile, and 4) to identify the normative relationship between longitudinal changes in neuroanatomy and electrophysiology in healthy participants, and to compare this to the relationship observed between these two indices in patients with FES. The aim of Chapter 2 was to use MRI to identify the neuroanatomical changes that occur over adolescence in healthy participants, and to identify the normative relationship between the neuroanatomical changes and electrophysiological changes associated with healthy periadolescent brain maturation. MRI and electroencephalographic (EEG) scans were acquired from 138 healthy participants between the ages of 10 and 30 years. The MRI scans were segmented into grey matter (GM) and white matter (WM) images, before being parcellated into the frontal, temporal, parietal and occipital lobes. Absolute EEG power was calculated for the slow-wave, alpha and beta frequency bands, for the corresponding cortical regions. The age-related changes in regional tissue volumes and regional EEG power were inferred with a regression model. The results indicated that the healthy participants experienced accelerated GM loss, EEG power loss and WM gain in the frontal and parietal lobes between the ages of 10 and 20 years, which decelerated between the ages of 20 and 30 years. A linear relationship was also observed between the maturational changes in regional GM volumes and EEG power in the frontal and parietal lobes. These results indicate that the periadolescent period is a time of great structural and electrophysiological change in the healthy human brain. The aim of Chapter 3 was to identify the GM abnormalities present in patients with FES, both at the time of their first presentation to mental health services (baseline), and over the first 2-3 years of their illness (follow-up). MRI scans were acquired from 41 patients with FES at baseline, and 47 matched healthy control subjects. Of these participants, 25 FES patients and 26 controls returned 2-3 years later for a follow-up scan. The analysis technique of voxel-based morphometry (VBM) was used in conjunction with the Statistical Parametric Mapping (SPM) software package in order to identify the regions of GM difference between the groups at baseline. The related analysis technique of tensor-based morphometry (TBM) was used to identify subjects’ longitudinal GM change over the follow-up interval. Relative to the healthy controls, the FES patients were observed to exhibit widespread GM reductions in the frontal, parietal and temporal cortices and cerebellum at baseline, as well as more circumscribed regions of GM increase, particularly in the occipital lobe. Furthermore, the FES patients lost considerably more GM over the follow-up interval than the controls, particularly in the parietal and temporal cortices. These results indicate that patients with FES exhibit significant structural brain abnormalities very early in the course of their illness, and that these abnormalities progress over the first few years of their illness. Chapter 4 employed the same methodology to investigate the white matter abnormalities exhibited by the FES subjects relative to the controls, both at baseline and over the follow-up interval. Compared to controls, the FES patients exhibited volumetric WM deficits in the frontal and temporal lobes at baseline, as well as volumetric increases at the fronto-parietal junction bilaterally. Furthermore, the FES patients lost considerably more WM over the follow-up interval than did the controls in the middle and inferior temporal cortex bilaterally. While there is substantial evidence indicating that abnormalities in the maturational processes of myelination play a significant role in the development of WM abnormalities in FES, the observed longitudinal reductions in WM were consistent with the death of a select population of temporal lobe neurons over the follow-up interval. The aim of Chapter 5 was to investigate the clinical correlates of the GM abnormalities exhibited by the FES patients at baseline. The volumes of four distinct cerebral regions where 31 patients with FES exhibited reduced GM volumes relative to 30 matched controls were calculated and correlated with patients’ scores on three primary symptom dimensions: Disorganization, Reality Distortion and Psychomotor Poverty. The results indicated that the greater the degree of atrophy exhibited by the FES patients in three of these four ‘regions-of-reduction’, the less severe their degree of Reality Distortion. These results suggest that an excessive amount of GM atrophy may in fact preclude the formation of hallucinations or highly systematized delusions in patients with FES. The aim of Chapter 6 was to identify the relationship between the longitudinal changes in brain structure and brain electrophysiology exhibited by 19 FES patients over the first 2-3 years of their illness, and to compare it to the normative relationship between the two indices reported in Chapter 2. The methodology employed for the parcellation of the MRI and EEG data was identical to Chapter 2. The results indicated that, in contrast to the healthy controls, the longitudinal reduction in GM volume exhibited by the FES patients was not associated with a corresponding reduction in EEG power in any brain lobe. In contrast, EEG power was observed to be maintained or even to increase over the follow-up interval in these patients. These results were consistent with the FES patients experiencing an abnormal elevation of neural synchrony. Such an abnormality in neural synchrony could potentially form the basis of the dysfunctional neural connectivity that has been widely proposed to underlie the functional deficits present in patients with schizophrenia. The primary aim of Chapter 7 was to assimilate the findings from the preceding empirical chapters with the theoretical framework provided in the literature, into an integrated and testable model of schizophrenia. The model emphasized dysfunctions in brain maturation, specifically in the normative processes of synaptic ‘pruning’ and axonal myelination, as playing a key role in the development of disintegrated neural activity and the subsequent onset of schizophrenic symptoms. The model concluded with the novel proposal that disintegrated neural activity arises from abnormal elevations in the synchrony of synaptic activity in patients with first-episode schizophrenia.

Spanish
Ph.D.
This dissertation explores vampire logic in Hispanic short fiction of the last decade of the 19th century and first three decades of the 20th century, and is thus a comparative study; not simply between Spanish and Latin American literary production, but also between Hispanic and European literary traditions. As such, this study not only draws attention to how Hispanic authors employed traditional Gothic conventions—and by extension, how Hispanic nations produced “modern” literature—but also to how these authors adapted previous models and therefore deviated from and questioned the European Gothic tradition, and accordingly, established trends and traditions of their own. This study does not pretend to be exhaustive. Even though I mention poetry, plays, and novels from the first appearance of the literary vampire in the mid-18th century through the fin de siglo and the first few decades of the 20th century, I focus on short fiction produced within and shortly thereafter the fin de siglo, as this time period saw a resurgence of the vampire figure on a global scale and the first legitimate appearance in Hispanic letters, being as it coincided with a rise in periodicals and short story production and represented developments and anxieties related to the physical and behavioral sciences, technological advances and urban development, waves of immigration and disease, and war. While Chapter 1 establishes a working theory of the vampire from a historical and materialist perspective, each of the following chapters explores a different trend in Hispanic vampire literature: Chapter 2 looks at how vampire narratives represent political and economic anxieties particular to Spain and Latin America; Chapter 3 studies newly married couples and how vampire logic leads to the death of the wife—and thus the death of the “angel of the house” ideal—therefore challenging ideas surrounding marriage, the family, and the home; lastly, Chapter 4 explores courting couples and how disruptions in the makeup of the public/private divide influenced images of female monstrosity—complex, parodic ones in the Hispanic case. One of the main conclusions this study reaches is that Hispanic authors were indeed producing Gothic images, but that these images deviated from the European Gothic vampire literary tradition and prevailing literary tendencies of the time through aesthetic and narrative experimentation and as a result of particular anxieties related to their histories, developments, and current realities. While Latin America and Spain produced few explicit, Dracula-like vampires, the vampire figures, metaphors, and allegories discussed in the chapters speak to Spain and Latin America’s political, economic, and ideological uncertainties, and as a result, their “place” within the modern global landscape. This dissertation ultimately suggests that Hispanic Gothic representations are unique because they were being produced within peripheral spaces, places considered “non-modern” because of their distinct histories of exploitation and development and their distinct cultural, religious, and racial compositions, therefore shifting perceptions of Otherness and turning the Gothic on its head. The vampire in the Hispanic context, I suggest, is a fusion of different literary currents, such as Romanticism, aesthetic movements, such as Decadence, and modes, such as the Gothic and the Fantastic, and is therefore different in many ways from its predecessors. These texts abound with complex representations that challenge the status quo, question dominant narratives, parody literary formulas, and break with tradition.
Temple University--Theses

Dans cette thèse, nous explorons de nouvelles méthodes d’analyse d’images pour la détection précoce des changements métaboliques cérébraux causés par la maladie d’Alzheimer. Nous introduisons deux apports méthodologiques que nous appliquons à un ensemble de données réelles. Le premier est basé sur l’apprentissage automatique afin de créer une carte des informations pertinentes pour la classification d'un ensemble d’images. Pour cela nous échantillonnons des blocs de Voxels selon un algorithme de Monte-Carlo. La mise en œuvre d’une classification basée sur ces patchs 3d a pour conséquence la réduction significative du volume de patchs à traiter et l’extraction de caractéristiques dont l’importance est statistiquement quantifiable. Cette méthode s’applique à différentes caractéristiques et est adaptée à des types d’images variés. La résolution des cartes produites par cette méthode peut être affinée à volonté et leur contenu informatif est cohérent avec des résultats antérieurs obtenus dans la littérature. Le second apport méthodologique porte sur la conception d’un nouvel algorithme de décomposition de tenseur d’ordre important, adapté à notre application. Cet algorithme permet de réduire considérablement la consommation de mémoire et donc en évite la surcharge. Il autorise la décomposition rapide de tenseurs, y compris ceux de dimensions très déséquilibrées. Nous appliquons cet algorithme en tant que méthode d’extraction de caractéristiques dans une situation où le clinicien doit diagnostiquer des stades précoces de la maladie d'Alzheimer en utilisant la TEP-FDG seule. Les taux de classification obtenus sont souvent au-dessus des niveaux de l’état de l’art
In this thesis we want to explore novel image analysis methods for the early detection of metabolic changes in the human brain caused by Alzheimer's disease (AD). We will present two methodological contributions and present their application to a real life data set. We present a machine learning based method to create a map of local distribution of classification relevant information in an image set. The presented method can be applied using different image characteristics which makes it possible to adapt the method to many kinds of images. The maps generated by this method are very localized and fully consistent with prior findings based on Voxel wise statistics. Further we preset an algorithm to draw a sample of patches according to a distribution presented by means of a map. Implementing a patch based classification procedure using the presented algorithm for data reduction we were able to significantly reduce the amount of patches that has to be analyzed in order to obtain good classification results. We present a novel non-negative tensor factorization (NTF) algorithm for the decomposition of large higher order tensors. This algorithm considerably reduces memory consumption and avoids memory overhead. This allows the fast decomposition even of tensors with very unbalanced dimensions. We apply this algorithm as feature extraction method in a computer-aided diagnosis (CAD) scheme, designed to recognize early-stage ad and mild cognitive impairment (MCI) using fluorodeoxyglucose (FDG) positron emission tomography (PET) scans only. We achieve state of the art classification rates

La senescència és l'etapa final del desenvolupament de la fulla i condueix a la mort. La senescència pot ser induïda prematurament per estrès abiòtic. La senescència primerenca o la senescència induïda per estrès abiòtic poden ser indesitjables i poden afectar al creixement i rendiment de les plantes. Hi ha una variació genètica considerable en els patrons de senescència del blat de moro. La senescència tardana o "stay-green" (SG) és un tret secundari que permet a les plantes de cultiu mantenir les seves fulles verdes i la seva capacitat de fotosíntesi durant més temps després de la floració. Els objectius d’aquesta tesi es van dividir en dos, el primer es l'avaluació de l'efecte del fenotip SG en els caràcters fenològics, fisiològics i agronòmics del blat de moro (Zea mays L.) i la avaluació de com els estressos abiòtics afecten a aquests trets. El segon objectiu es identificar gens diferencialment expressats (DEGs) durant la senescència de diverses línies pures de blat de moro contrastant pel fenotip SG, i mostrar com canvia la seva expressió sota estrès abiòtic. El primer objectiu consisteix en una avaluació de vuit línies pures de blat de moro amb fenotip SG contrastant. L'experiment es va realitzar durant dos anys consecutius: 2018 i 2019. L'avaluació es va realitzar en dos ambients, amb dues repeticions en cada ambient per a cada any d'experiment. Els vuit genotips van ser avaluats sota dos nivells d'aigua (amb estrès hídric i condicions hídriques òptimes) i tres nivells de nitrogen: N1 (0U), N2 (30U) i N3 (90U). Després, l'últim factor estudiat va ser la densitat de plantes, amb dos nivells de densitat, alta densitat de plantes (80000 plant ha-1) i baixa densitat de plantes (50000 plant ha-1). A més, per al segon objectiu utilitzem dos genotips representatius del total de genotips utilitzats en el primer objectiu, un amb fenotip SG i un altre amb senescència primerenca. Per respondre a aquest objectiu, es va realitzar una anàlisi de RNAseq per a diferents mostres recollides durant diferents temps de senescència, a partir de la floració. Pel que fa al primer objectiu, els resultats mostren que els genotips SG tenen una millor resposta per a la majoria dels trets mesurats. La sequera i el nitrogen són els factors estressants més importants que afecten negativament a l'activitat fisiològica de la planta i al seu rendiment, i tenen un efecte més gran per a promoure la senescència de les fulles. La densitat de la planta té un efecte positiu per a la biomassa màxima i per el rendiment de gra, però, pot reduir el rendiment de la planta individual i afectar la qualitat del gra. Per al segon objectiu de l'expressió de gens, el resultat revela que diversos gens s'activen o reprimeixen durant el període de senescència. Aquests gens, s’activen o reprimeixen abans per al genotip de senescència primerenca i van retardar aquesta expressió per als genotips amb senescència tardana. També es va identificar l'expressió d'alguns gens específics corresponents a cada estrès abiòtic o estressos combinats. Els gens que van reprimir la seva expressió estaven involucrats principalment en la fotosíntesi, en diferents processos de biosíntesi i en el metabolisme. Mentre que els gens que van augmentar la seva expressió participaven en processos de degradació i catabolisme, i en diferents processos d'estímul davant estrès abiòtic. A més, durant el procés de senescència i sota diferents estressos abiòtics, vam mostrar l'expressió de diferents TF relacionats amb la senescència i la resposta a l'estrès abiòtic. Del resultat d'aquests estudis podem concloure que la senescència foliar està sota control genètic. Es pot veure afectat per diferents estressos abiòtics, que poden afectar negativament a la fisiologia i el rendiment de la planta. No obstant això, retardar la senescència de les fulles pot ser una característica més útil per mantenir l'activitat fisiològica de la planta durant més temps que per augmentar la biomassa i el rendiment de gra.
La senescencia es la etapa final del desarrollo de la hoja y conduce a la muerte. La senescencia puede ser inducida prematuramente por estrés abiótico. La senescencia temprana o la senescencia inducida por estrés abiótico pueden ser indeseables y pueden afectar el crecimiento y rendimiento de las plantas. Existe una variación genética considerable en los patrones de senescencia del maíz. La senescencia tardía o “stay-green” (SG) es un rasgo secundario que permite a las plantas de cultivo mantener sus hojas verdes y su capacidad de fotosíntesis durante más tiempo después de la floración. Los objetivos de esta tesis se dividieron en dos importantes estudios, en primer lugar, la evaluación del efecto del fenotipo SG en los caracteres fenológicos, fisiológicos y agronómicos del maíz (Zea mays L.); y evaluar cómo los estreses abióticos afectan estos caracteres. El segundo objetivo fue identificar genes diferencialmente expresados (DEGs) durante la senescencia para líneas puras de maíz contrastante para el fenotipo SG, y mostrar cómo cambia su expresión bajo estrés abiótico. El primer objetivo consiste a una evaluación de ocho líneas puras de maíz con diversa expresión de fenotipo SG. El experimento se realizó por dos años consecutivos 2018 y 2019. La evaluación se realizó en dos ambientes, con dos repeticiones en cada ambiente para cada año de experimento. Los ocho genotipos evaluados bajo dos niveles de agua, con estrés hídrico y condiciones hídricas óptimas; tres niveles de nitrógeno, N1 (0U), N2 (30U) y N3 (90U). El último factor estudiado fue la densidad de plantas, con dos niveles de densidad, alta densidad de plantas (80000 plant ha-1) y baja densidad de plantas (50000 plant ha-1). Además, para el segundo objeto utilizamos dos genotipos representativos de los genotipos utilizados en el primer objetivo, uno con fenotipo SG y otro con senescencia temprana. Para responder a este objetivo, se realizó un análisis de RNAseq para diferentes muestras recolectadas durante diferentes tiempos de senescencia, a partir de la floración. Para el primer objetivo, el resultado muestra que los genotipos SG tienen un mejor comportamiento para la mayoría de los caracteres medidos. La sequía y el nitrógeno son los factores estresantes más importantes que afectan negativamente la actividad fisiológica de la planta y el rendimiento y promueven la senescencia de las hojas. La densidad de la planta tiene un efecto positivo para la biomasa máxima y el rendimiento de grano, sin embargo, puede reducir el rendimiento de la planta individual y afectar la calidad del grano. Para el segundo objetivo de la expresión de genes, el resultado revela que varios genes se activan o reprimen durante el período de senescencia. Estos genes fueron activados o reprimidos antes para el genotipo de senescencia temprana, y retrasaron esta expresión para el genotipo con senescencia tardía. También identificamos la expresión de algunos genes específicos correspondientes a cada estrés abiótico o estreses combinados. Los genes que retrasan su expresión estaban involucrados principalmente en la fotosíntesis, diferentes procesos de biosíntesis y metabolismo. Mientras que los genes que incrementaron su expresión participan en el proceso de degradación y catabolismo, y en diferentes procesos de estímulo bajo estrés abiótico. Además, durante el proceso de senescencia y bajo diferentes estreses abióticos, mostramos la expresión de diferentes factores de transcripción relacionados con la senescencia y la respuesta al estrés abiótico. Del resultado anterior de estos estudios, podemos concluir que la senescencia foliar estaba bajo control genético. Puede verse afectada por diferentes estreses abióticos, que pueden afectar negativamente la fisiología y el rendimiento de la planta. Sin embargo, retrasar la senescencia de las hojas puede ser una característica útil para mantener la actividad fisiológica de la planta durante más tiempo que para aumentar la biomasa y el rendimiento de grano.
Senescence is the final stage of leaf development and leads to death. Senescence can be induced prematurely by abiotic stresses. Early senescence or induced senescence by abiotic stresses can be undesirable, affecting the growth and yield of plants. There is considerable genetic variation in the patterns of senescence in maize. The stay-green (SG) is a secondary trait that enables crop plants to maintain their green leaves and photosynthesis capacity for a longer time after silking. The objectives of this thesis were divided into two essential studies. Firstly, evaluate the effect of SG phenotype for maize (Zea mays L.) phenological, physiological, and agronomic characters; and assess how abiotic stresses affect these traits. The second objective was to identify genes differentially expressed (DEGs) during senescence for contrasting SG phenotype in inbred lines and to show how their expression changes under abiotic stresses. The first objective was made with eight inbred lines with contrasting SG phenotypes. The experiments were carried out for two successive years experiment 2018 and 2019. The evaluation was made in two locations, with two repetitions in each location for each year trial. The eight genotypes were evaluated under two water levels, with water stress and optimum water conditions; three nitrogen levels, N1 (0U), N2 (30U), and N3 (90U). The last factor studied was plant density, with two levels of high plant density (80000 plant ha-1) and low plant density (50000 plant ha-1). For the second objective, we used two representative genotypes from the complete set of genotypes used in the first objective, one with SG phenotype and the other with early senescence rate. RNA-seq analysis was made for different samples collected during different senescence stages, starting from silking to support the objective. For the first objective, the result shows that SG genotypes have better performance for most measured traits. Drought and nitrogen are the most critical stresses that negatively affect plant physiological activity and yield and promote leaf senescence. Plant density has a positive effect on maximal biomass and grain yield. However, it can reduce the individual plant yield and affect grain quality. For the second objective of genes’ expression, the results reveal that several genes are activated or repressed during the senescence period. Those genes were activated or repressed earlier for early senescence genotype, and these expressions were delayed for the stay-green line. We also identified the expression of some specific genes corresponding to each abiotic stress or combined stress. Down-regulated genes were mainly involved in photosynthesis, different processes of biosynthesis and metabolism. In contrast, the upregulated genes are involved in the degradation and catabolism process and different stimulus processes under abiotic stress. Furthermore, during the senescence process and under different abiotic stresses, we showed the expression of different transcription factors related to senescence and response to abiotic stress. From the previous result of these studies, we conclude that leaf senescence was under genetic control. It can be affected by different abiotic stresses, which can negatively affect plant physiology and yield. However, delaying leaf senescence can be helpful to maintain plant physiological activity for a long time then increase biomass and grain yield.

Les troubles mnésiques sont fréquents dans la sclérose en plaques (SEP) mais leurs substrats anatomique et biologique sont mal connus. L’objectif de cette thèse translationnelle était de comprendre les mécanismes physiopathologiques des troubles mnésiques à la phase précoce de la SEP, avec pour perspective de trouver de nouvelles cibles thérapeutiques et de définir de nouveaux marqueurs d’imagerie. Nous avons réalisé une analyse neuropsychologique et IRM de patients atteints de forme précoce de SEP et nous avons étudié des souris à la phase précoce d’une encéphalomyélite auto-immune expérimentale (EAE, le modèle animal de la SEP) avec une combinaison d’expériences comportementales, d’IRM, histologiques, électrophysiologiques et pharmacologiques. Nous avons démontré que l’atteinte hippocampique était précoce dans l’histoire de la maladie et qu’elle était corrélée au déclin mnésique des patients atteints de SEP. Nous avons identifié chez les souris EAE que la structure et la fonction du gyrus denté étaient plus vulnérables que les autres sous-champs de l’hippocampe au stade précoce de la maladie et nous avons transposé cette découverte à la pathologie humaine en démontrant une perte des capacités de pattern separation chez des patients atteints de forme précoce de SEP. Du point de vue mécanistique, nous avons démontré que l’activation microgliale précoce était responsable de l’atteinte du gyrus denté et des troubles mnésiques dans l’EAE et que cette cascade physiopathologique pouvait être prévenue grâce à un traitement par minocycline. Du point de vue de l’imagerie, nous avons également démontré que l’atteinte microstructurale de l’hippocampe ainsi que la neurodégénérescence précoce du gyrus denté pouvaient être étudiées in vivo en tenseur de diffusion (DTI). Nous travaillons à la mise en place de méthode encore plus spécifique par l’imagerie de densité neuritique et d’orientation/dispersion (NODDI). Nos résultats relient l’atteinte mnésique précoce de la SEP à une neurodégénérescence sélective du gyrus denté. Ce processus physiopathologique peut être prévenu en inhibant l’activation microgliale chez les souris EAE et peut être étudié in vivo grâce au DTI chez la souris comme chez l’homme, offrant d’évidentes perspectives cliniques dans la prise en charge des patients atteints de SEP
Memory impairment is frequent in multiple sclerosis (MS) but its anatomical and biological substrates are poorly understood. The objective of this translational thesis was to understand the pathophysiological mechanisms of early memory impairment in MS, to find new potential therapeutic targets and to define new imaging biomarkers related to memory impairment. We used neuropsychological and MRI experiments in patients with early MS and we explored experimental autoimmune encephalomyelitis (EAE) mice (a mouse model of MS) at the early stage of the disease with a combination of behavioral, in vivo MRI, histological, electrophysiological and pharmacological approaches. In patients with MS, we demonstrated that hippocampal damage occurs early during the course of the disease and that it correlates with memory impairment. In EAE-mice, we identified that dentate gyrus structure and function are more vulnerable than other hippocampal subfields at the early stage of the disease and we translated this finding back to humans by demonstrating loss of pattern separation performances in patients with early MS. From a mechanistic point of view, we demonstrated that early microglial activation causes dentate gyrus disruption and memory impairment in EAE-mice and that this pathophysiological cascade can be prevented with minocycline. From the imaging point of view, we demonstrated that hippocampal microstructural damage and early dentate gyrus degeneration can be monitored in vivo with diffusion tensor imaging (DTI). We are currently developing more specific imaging approaches with optimization of the Neurite Orientation Dispersion and Density Imaging (NODDI) to assess hippocampal subfields. Our results link early memory impairment in MS to a selective disruption of the dentate gyrus. We were able to prevent this neurodegenerative process with microglial inhibitors in EAE-mice and to capture these features non-invasively with DTI in both humans and rodents, paving the way toward new clinical perspectives in MS

O objetivo principal deste trabalho é o estudo de transistores MuGFETs de porta tripla de Corpo de canal tipo-n com e sem a aplicação da configuração DTMOS. Este estudo será realizado através de simulações numéricas tridimensionais e por caracterizações elétricas. A corrente de dreno, a transcondutância, a resistência, a tensão de limiar, a inclinação de sublimiar e a Redução da Barreira Induzida pelo Dreno (DIBL) serão analisadas em modo DTMOS e em configuração de polarização convencional. Importantes figuras de mérito para o desempenho analógico como transcondutância-sobre-corrente de dreno, a condutância de saída, a tensão Early e o ganho de tensão intrínseco serão estudados tanto experimentalmente como através de simulações numéricas tridimensionais para diferentes concentrações de dopantes no canal. Os resultados indicam que a configuração DTMOS apresenta as características elétricas superiores (4 e 10 %) e maior eficiência dos transistores. Além disso, os dispositivos DTMOS com alta concentração de dopantes no canal apresentaram um desempenho analógico muito melhor quando comparados ao transistor de porta tripla de Corpo em modo de operação convencional. O ruído de baixa frequência (LF) é pela primeira vez experimentalmente analisado na região linear e saturação. A origem do ruído é analisada de maneira a compreender os mecanismos físicos envolvidos neste tipo de ruído. As medições mostraram que os espectros do sinal dos dispositivos de porta tripla de Corpo e DTMOS são compostos por flutuações referentes ao número de portadores devido ao ruído flicker e por ondas de ruído de geração e recombinação no dielétrico de porta que se torna maior com o aumento da tensão de porta. No entanto, o principal fato desta análise é que o dispositivo DTMOS apresentou praticamente a mesma magnitude do ruído LF na região linear e de saturação que o dispositivo de Corpo. A energia de 60 MeV na fluência de p/1012 cm-2 de radiações de prótons é também estudada experimentalmente em termos das características elétricas, desempenho do analógico e ruído LF nos dispositivos de porta tripla de Corpo e DTMOS. Os resultados indicam que combinado com as suas melhores características elétricas e um ótimo desempenho analógico do DTMOS, faz o transistor de porta tripla de Corpo um candidato muito competitivo para aplicações analógicas em ruído de baixa frequência antes e depois da irradiação. A vantagem da técnica DTMOS em transistores de porta tripla em ambientes onde os dispositivos têm de suportar alta radiação é devido à menor penetração do campo de dreno que reduz o efeito das cargas induzidas pelo óxido de isolação (STI). Finalmente, o transistor de Corpo de porta tripla de canal tipo-n é experimentalmente estudado como célula de memória, isto é, como 1T-DRAM (Memória de Acesso Aleatório Dinâmico com 1 transistor). Para escrever e ler 1 é utilizado um modo de programação que utiliza o efeito do transistor bipolar parasitário (BJT) enquanto a polarização direta da junção do corpo e do dreno é usada para escrever 0. As correntes de leitura e escrita aumentam com o aumento da tensão do corpo (VB) porque as cargas induzidas pelo efeito BJT é armazenada dentro da aleta. Quando o corpo do transistor está flutuante, o dispositivo retém mais cargas dentro da sua aleta. Além disso, transistor de Corpo pode ser utilizado como 1T-DRAM com eletrodo de porta e substrato flutuando. Neste caso, o dispositivo funciona como um biristor (sem porta).
The main goal of this work is to investigate the n-channel MuGFETs (triple-gate) Bulk transistors with and without the application of DTMOS operation. This work will be done through three-dimensional numerical simulation and by electrical characterizations. The drain current, transconductance, resistance, threshold voltage, subthreshold swing and Drain Induced Barrier Lowering (DIBL) will be analyzed in the DTMOS mode and the standard biasing configuration. Important figures of merit for the analog performance such as transconductance-over-drain current, output conductance, Early voltage and intrinsic voltage gain will be studied experimentally and through three-dimensional numerical simulations for different channel doping concentrations. The results indicate that the DTMOS configuration has superior electrical characteristics (4 e 10 %) and higher transistor efficiency. In addition, DTMOS devices with a high channel doping concentration exhibit much better analog performance compared to the normal operation mode. Low-Frequency (LF) noise is for the first time experimentally investigated in linear and saturation region. The origin of the noise will be analyzed in order to understand the physical mechanisms involved in this type of noise. Measurements showed that the signal spectra for Bulk and DTMOS are composed of number fluctuations related flicker noise with on top generation and recombination noise humps, which become more pronounced at higher gate voltage. However, the most important finding is the fact that DTMOS devices showed practically the same LF noise magnitude in linear and saturation region than standard Bulk device. Proton irradiation with energy of 60 MeV and fluence of p/1012 cm-2 is also experimentally studied in terms of electric characteristic, analog performance and the LF noise in Bulk and DTMOS triple gate devices. The results indicate that the combined of the better electrical characteristics and an excellent analog performance of DTMOS devices, makes it a very competitive candidate for low-noise RF analog applications before and after irradiation. The advantage of dynamic threshold voltage in triple gate transistors in environments where the devices have to withstand high-energy radiation is due to its lower drain electric field penetration that lowers the effect of the radiation-induced charges in the STI (shallow trench isolation) regions adjacent to the fin. Finally, the n-channel triple gate Bulk device is used for memory application, that is, 1T-DRAM (Dynamic Random Access Memory with 1 Transistor). Bipolar junction transistor (BJT) programming mode is used to write and read 1 while the forward biasing of the body-drain junction is used to write 0. The reading and writing current increases with increasing body bias (VB) because the load induced by the BJT effect is stored within the fin. When the body of the transistor is floating, the device retains more charge within its fin. In addition, transistor could also operate as 1T-DRAM with both gate and bulk contacts floating, which is similar to the biristor (gateless) behavior.

Les troubles cognitifs sont fréquents dans la sclérose en plaques (SEP) mais leurs mécanismes sous-jacents sont encore mal connus. Les techniques d’IRM ont été indispensables pour essayer de mieux comprendre les substrats biologiques des processus cognitifs. L’objectif de cette thèse est de mieux comprendre les mécanismes physiopathologiques du fonctionnement cognitif dans les stades précoces de la SEP. Pour cela, nous avons étudié une cohorte de patients atteints de syndrome cliniquement isolé (SCI) pendant un an, en réalisant une batterie de tests neuropsychologiques ainsi qu’un examen IRM. Nous avons tout d’abord démontré une atteinte précoce de la substance grise, en particulier au niveau de l’hippocampe, se propageant vers le cortex après un an d’évolution. L’atteinte microstructurale précoce de l’hippocampe était capable de prédire sa perte de volume. Ensuite, nous nous sommes intéressés à la réorganisation des réseaux cérébraux fonctionnels à ce stade précoce de la maladie. En utilisant l’IRM fonctionnelle de repos, nous avons démontré une réorganisation cérébrale fonctionnelle précoce impliquant plusieurs régions cérébrales. Cette réorganisation était encore plus prononcée après un an d’évolution. Au même moment, nos patients présentaient un fonctionnement cognitif normal qui était associé au niveau de réorganisation cérébrale présente. Ces résultats suggèrent un mécanisme de compensation aux stades précoces de la pathologie. La relation entre ces modifications fonctionnelles et l’anatomie sous-jacente est inconnue dans la SEP. Nous avons ainsi décidé de combiner l’IRM fonctionnelle de repos et l’imagerie par tenseurs de diffusion pour étudier à la fois la connectivité fonctionnelle et la connectivité structurelle. En utilisant le paramètre de couplage structurel-fonctionnel, nous avons démontré un découplage, un an après l’apparition de la maladie, au niveau de trois réseaux cérébraux du repos (salience, visuel et somato-moteur). Ce découplage était observé alors même que les performances cognitives de nos patients étaient préservées et que la réorganisation fonctionnelle était présente. Ces résultats suggèrent que cette réorganisation fonctionnelle à ce stade, agissant comme un mécanisme de compensation, se produit à travers des connections anatomiques indirectes. Afin de confirmer ces résultats et de suivre l’évolution des réseaux cérébraux et leur impact sur la cognition, nous avons recontacté nos patients SCI pour un suivi à 5 ans
Cognitive impairment is frequent in multiple sclerosis (MS) but its underlying mechanisms are still poorly understood. MRI techniques have been a valuable tool to investigate the biological substrates of cognitive processes. The objective of this thesis was to better understand the pathophysiological mechanisms of cognitive functioning at the early stage of MS. We followed clinically isolated syndrome (CIS) patients for one year, using neuropsychological tests, conventional and more advanced MRI techniques. We first demonstrated a differential gray matter vulnerability at the beginning of MS with a pathological spread from the hippocampus towards the cortex. We showed that the first microstructural alterations taking place within the hippocampus were able to predict its future volume loss. After that, we were interested in the potential brain functional reorganization at this stage of the disease. Using resting-state functional MRI, we were able to demonstrate very early regional brain functional reorganization starting from the disease onset and becoming more pronounced after one year of evolution. We also noticed a preservation of cognitive performances in CIS patients, which we found was associated to more functional reorganization. These results suggested then a compensation mechanism at the first year after a CIS. However, the relationship between these functional changes and the underlying anatomy was still missing. Thus, we combined resting-state functional MRI and diffusion tensor imaging to represent both functional and structural connectivity. Using the structural-functional coupling parameter, representing the association between structural and functional connections, we showed a decoupling one year after the disease onset in three major networks (salience, visual and somatomotor networks). This decoupling was noticed while cognitive performances were preserved and functional reorganization present. These last results led us to suggest that the functional reorganization at this stage, acting as a compensation mechanism, occurs along indirect anatomical pathways. In order to confirm these results and further follow-up brain networks topology and its impact on cognition, we are currently calling back our CIS patients for their 5-year visit

La fissuration d’éléments minces en béton dès le jeune âge correspond à une réalité observée sur des ouvrages en construction. Cette fissuration concerne des bétons courants de bâtiments, pour lesquels les matériaux de qualité optimale ne sont pas toujours disponibles, en particulier au niveau des granulats. Le but de cette thèse est de définir une approche expérimentale d’étude de ces phénomènes et de proposer des interprétations pour les sensibilités relatives à la fissuration en fonction de la nature des granulats et de leurs taux de saturation initiaux. La sensibilité des moyens de mesures existants conçus pour des bétons spéciaux (BAP et BHP) a d’abord dû être

vérifiée. Un nouveau dispositif expérimental a été développé dans le but de mieux décrire l’évolution de la résistance et de la capacité de

déformation en traction du béton jeune. Les indicateurs globaux (macroscopiques) apparaissent plus sensibles que les indicateurs de la microstructure pour rendre compte des différences de comportement observées. L’évolution du module élastique, du retrait plastique et endogène corrélées à l’évolution de la capacité de déformation et de la résistance en traction permettent de mieux caractériser le risque

potentiel de fissuration par retrait empêché. La fin de prise correspond à une phase critique. L’influence de la saturation des granulats est

indirecte, et résulte des variations du rapport Eau d’ajout/Ciment, à rapport Eau efficace/Ciment constant. La nature des granulats intervient au niveau des évolutions relatives de la résistance en traction et du module élastique. La méthodologie peut être appliquée à l’étude d’autres types de bétons et d’autres paramètres de formulation.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

The autogenous shrinkage due to self-desiccation of high- and ultra-high performance concretes with very low water-cement ratio in case of restraint leads to considerable stresses starting from very early age. The resultant risk of cracking presently cannot be adequately investigated. Parameters that are particularly difficult to capture experimentally are the concrete temperature and the viscoelasticity. The primary objective of this work was to assess as precise as possible the autogenous shrinkage cracking propensity of representative concretes at strong restraint and constant room temperature. Test methods needed to be chosen and enhanced in a way that preferably allowed for the efficient and precise investigation of all relevant factors in the future. Ideally, a method suitable for a complete empirical modeling was provided. First the methodological requirements and the advantages and disadvantages of existing test methods were discussed. Based on this, optimized test methods were proposed. Their suitability was verified using the example of ultra-high strength concrete. The choice of concrete compositions considered the essential measures for reducing shrinkage (internal curing, shrinkage-reducing admixtures, reduction of the fraction of Portland cement in the binder). The autogenous shrinkage was measured with the shrinkage cone method. This new test method was validated by investigations of the repeatability and reproducibility and proved efficient and precise. It allows for measurements under non-isothermal conditions; no established test method exists for that purpose to date. The autogenous shrinkage of the ultra-high strength concretes at the age of 24 h, investigated under quasi-isothermal conditions (20 °C), was between 0,25 mm/m and 0,70 mm/m. It was particularly low when a shrinkage-reducing admixture was added and when superabsorbent polymers were used. The stresses due to restraint were determined with the restrained ring test. A large part of the stresses to be expected according to Hooke’s Law were eliminated by creep and relaxation. The relaxation capacity being very pronounced at very early age was the main reason that no visible cracking occurred, not even with the concretes with high autogenous shrinkage. The development of the autogenous shrinkage cracking propensity was described as ratio of restraint stress and splitting tensile strength. By means of modified ring tests, used to determine the maximum tensile stress, it could be shown that the ratio of stress to strength is an appropriate failure criterion. However, the cracking propensity can be calculated correctly only if the strongly age-dependent ratio of uniaxial to splitting tensile strength is accounted for. Besides, it needs to be considered that at very early age a plastic stress redistribution may occur in restrained ring tests. The reference concrete showed a high cracking propensity of up to 0.68. The fact that shrinkage-reducing measures led to significantly lower values reveals their relevance for the safe application of ultra-high strength concrete. However, the investigations carried out here at 20 °C do not allow for a final assessment of the cracking propensity under typical on-site conditions. To empirically model the autogenous shrinkage cracking propensity as a function of temperature and stress level in the future, an analytical stress solution for non-isothermal restrained ring tests and a new approach for investigating the residual stress and relaxation capacity by means of non-passive restrained ring tests was suggested
Das durch Selbstaustrocknung verursachte autogene Schwinden von besonders leistungsfähigen Betonen mit sehr niedrigem Wasserzementwert führt bei Dehnungsbehinderung bereits in sehr frühem Alter zu erheblichen Zwangsspannungen. Die Gefahr der Rissbildung, die sich daraus ergibt, lässt sich bislang nur unzureichend untersuchen. Experimentell besonders schwer zu erfassende Faktoren sind die Betontemperatur und die Viskoelastizität. Das vorrangige Ziel der Arbeit war die möglichst genaue Ermittlung der autogenen Schwindrissneigung repräsentativer Betone bei starker Dehnungsbehinderung und konstanter Raumtemperatur. Dabei waren die Prüfverfahren möglichst so zu wählen und weiterzuentwickeln, dass sich zukünftig alle relevanten Faktoren effizient und genau untersuchen lassen. Im Idealfall sollte eine Methode entstehen, die eine vollständige empirische Modellierung erlaubt. Zunächst wurden die methodischen Anforderungen und die Vor- und Nachteile existierender Prüfverfahren diskutiert. Darauf aufbauend wurden optimierte Verfahren vorgeschlagen. Ihre Eignung wurde an ultrahochfestem Beton überprüft. Bei der Auswahl der Betone wurden die wesentlichen Maßnahmen zur Schwindreduzierung berücksichtigt (innere Nachbehandlung, schwindreduzierende Zusatzmittel, Verringerung des Portlandzementanteils am Bindemittel). Das autogene Schwinden wurde mit dem Schwindkegelverfahren gemessen. Das neue Verfahren wurde durch Untersuchungen zur Wiederhol- und Vergleichsgenauigkeit validiert und erwies sich als effizient und genau. Es ermöglicht Messungen unter nicht-isothermen Bedingungen; hierfür existiert bisher kein etabliertes Verfahren. Das autogene Schwinden der untersuchten ultrahochfesten Betone unter quasi-isothermen Bedingungen (20 °C) betrug im Alter von 24 h zwischen 0,25 mm/m und 0,70 mm/m. Besonders gering war es bei Zugabe eines schwindreduzierenden Zusatzmittels bzw. Verwendung superabsorbierender Polymere. Mit dem Ring-Test wurden die bei Dehnungsbehinderung entstehenden Spannungen ermittelt. Ein großer Teil der gemäß Hooke’schem Gesetz zu erwartenden Spannungen wurde durch Kriechen und Relaxation abgebaut. Die im sehr frühen Alter stark ausgeprägte Relaxationsfähigkeit war der wesentliche Grund dafür, dass es selbst bei Betonen mit hohem autogenen Schwinden zu keiner erkennbaren Rissbildung kam. Die Entwicklung der autogenen Schwindrissneigung wurde als Verhältnis von Zwangsspannung und Spaltzugfestigkeit beschrieben. Durch modifizierte Ring-Tests, mit deren Hilfe die maximale Zugspannung ermittelt wurde, konnte gezeigt werden, dass das Verhältnis von Spannung und Festigkeit als Versagenskriterium geeignet ist. Die Rissneigung lässt sich aber nur dann korrekt berechnen, wenn das stark altersabhängige Verhältnis von einaxialer Zugfestigkeit und Spaltzugfestigkeit berücksichtigt wird. Außerdem ist zu beachten, dass es im sehr frühen Alter zu einer plastischen Spannungsumlagerung in Ring-Tests kommen kann. Der Referenzbeton wies eine hohe Rissneigung von bis zu 0,68 auf. Dass die schwindreduzierenden Maßnahmen zu deutlich geringeren Werten führten, zeigt deren Bedeutung für den sicheren Einsatz von ultrahochfestem Beton. Die hier bei 20 °C durchgeführten Untersuchungen erlauben allerdings keine abschließende Bewertung der Rissneigung unter baustellentypischen Bedingungen. Um die autogene Schwindrissneigung zukünftig als Funktion der Temperatur und des Lastniveaus empirisch modellieren zu können, wurden eine analytische Spannungslösung für nicht-isotherme Ring-Tests und ein neuer Ansatz zur Untersuchung der Resttrag- und Relaxationsfähigkeit mit Hilfe nicht-passiver Ring-Tests vorgeschlagen

A l’heure actuelle où la préservation de notre environnement est primordiale, les constructions en béton font intervenir de plus en plus des ciments comprenant des ajouts minéraux, tels que le laitier, les cendres volantes… En effet, la production des ciments composés permet de réduire le dégagement des gaz à effets de serre et de réutiliser des déchets industriels. Les bétons formulés à base de ciment au laitier de haut-fourneau (CEM III) sont également largement utilisés suite à leur bonne résistance aux réactions alcali-silices, à la diffusion des chlorures et aux attaques sulfatiques… Cependant, certains ouvrages construits avec ce type matériau ont présenté au jeune âge des problèmes de fissuration liés à la restriction de leurs déformations différées, telles que le retrait endogène, thermique et de dessiccation. Suite à cette observation, des essais préliminaires ont été réalisés au laboratoire du service BATir de l’Université Libre de Bruxelles. Ils ont mis en avant plusieurs caractéristiques du comportement de ces matériaux :

1. Lors du suivi du retrait restreint à l’aide de l’essai à l’anneau en condition de dessiccation, le béton formulé à base de ciment au laitier de haut-fourneau a fissuré bien avant le béton formulé à base de ciment Portland.

2. Le retrait total en condition libre du béton formulé à base de ciment au laitier de haut-fourneau est nettement supérieur à celui du béton formulé à base de ciment Portland. Cette différence de comportement est principalement due à l’accroissement rapide et plus élevé du retrait endogène des bétons formulés à base de ciment au laitier de haut-fourneau.

Au vu de ces résultats expérimentaux, il a semblé intéressant de déterminer quel était l’impact de la déformation endogène des bétons formulés à base de ciments au laitier de haut-fourneau (CEM III) sur leur sensibilité à la fissuration. Afin de répondre à cette question, les déformations différées (retrait endogène, fluage propre en compression et en traction) au jeune âge de trois compositions de béton avec différentes teneurs en laitier (0, 42 et 71%) ont été étudiées expérimentalement en conditions libre et restreinte. Cependant, le suivi du retrait endogène libre et restreint a nécessité le développement de plusieurs dispositifs expérimentaux limitant au maximum les artefacts de mesure, tels que la TSTM (Temperature Stress Testing Machine). De plus, l’interprétation de ces résultats expérimentaux a également nécessité une caractérisation du comportement de ces matériaux à l’échelle macro- et microscopique.

Finalement, cette étude a montré que malgré une déformation endogène plus élevée, les bétons formulés à base de ciment au laitier de haut-fourneau fissurent après le béton formulé à base de ciment Portland. Ce comportement est dû à :

-l’impact du laitier sur la réaction d’hydratation du matériau cimentaire ;

-la présence d’une expansion de la matrice cimentaire des bétons formulés à base de ciment au laitier de haut-fourneau au jeune âge qui retarde l’apparition des contraintes de traction au sein du matériau ;

-la plus grande capacité de ces matériaux cimentaires à relaxer les contraintes de traction/

Today, the use of concretes with mineral additions (fly ash, slag) for civil engineering structures is spreading worldwide. Indeed, the production of blended cements is more respectful of the environment than the production of Portland cement, because it allows reducing greenhouse gas emissions and using industrial wastes. Slag cement concretes are also largely used for their good resistance to alkali-silica reactions, sulphate attacks and chloride diffusion. However, some of constructions built with slag cement concretes have exhibited cracking at early age due to their restrained deformations, such as thermal, autogenous and drying shrinkage. Following these observations, a preliminary experimental study was realized in the laboratory of BATir Department at ULB. It revealed several characteristics of the behaviour of slag cement concretes:

1. The study of restrained deformations under drying conditions by means of ring tests showed that the slag cement concretes seem more prone to crack than the Portland cement concretes;

2. The total free shrinkage for slag cement concrete is clearly larger than for Portland cement concrete. This difference of behaviour is mainly due to the fast and large increase in the autogenous deformation of the slag cement concrete.

Following these experimental results, the effect of the autogenous deformation on the cracking sensibility of slag cement concretes seemed interesting to investigate. Their deformations (autogenous deformation, compressive and tensile basic creep) have been studied at early age for three concretes characterized by different slag contents (0, 42 and 71%) under free and restrained conditions. For monitoring free and restrained autogenous deformations, several test rigs aimed at limiting artefacts were designed, like the TSTM (Temperature Stress Testing Machine). Moreover, the behaviour of these concretes was also characterized by a study at a macro- and microstructure scale.

Finally, this study shows that the slag cement concretes under sealed and fully restrained conditions crack later than the Portland cement concrete, despite the fact that they are characterized by the largest autogenous deformation. This behaviour is due to:

- the slag effect on the hydration reaction of cementitious material;

- the cement matrix expansion of the slag cement concretes at early age which delays the occurrence of tensile stresses inside the material;

- the largest capacity of this concrete to relax tensile stresses.

Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Genetic engineering of superior wood properties and exploiting natural genetic variation found within commercially important trees, such as Eucalyptus spp., promise to increase cellulose biomass production. It is therefore essential to understand the molecular genetics of wood formation. Digital Gene Expression (DGE) profiling is adept in not only assessing the expression level of genes transcriptome-wide, but also in characterising alternative splice forms of transcripts and identifying novel transcripts. Tension wood is a specialised type of wood which functions in the response to mechanical stress in trees and is formed on the upper side of a branch or a bent stem. The characteristics of tension wood differ from normal wood by increased cellulose and xyloglucan content and decreased lignin and xylan content. During tension wood formation, transcriptome-wide changes in the expression of genes involved in secondary cell wall formation underlie changes in cell wall composition. Most notably is an increase in fasciclin-like arabinogalactan protein (FLA) and xyloglucan endotransglucosylase (XTH) and a decrease in lignin biosynthesis gene expression. Differential expression patterns are shown by cellulose synthase (CesA) genes, which have been found to be either up- or down-regulated during tension wood formation. No previous study has profiled gene expression during early as well as late tension wood formation. The aim of this M.Sc study was to identify genes that are differentially expressed during early tension wood induction and late tension wood formation in the immature xylem tissues of Eucalyptus grandis x Eucalyptus urophylla hybrid trees. DGE profiling is a transcriptome-wide expression profiling technique based on ultra-high throughput second generation DNA sequencing technology. The processing, analysis and interpretation of DGE data has not yet been standardised. To address this problem, a case study was performed of DGE data mapping to seven well characterised Eucalyptus grandis CesA (EgCesA) genes. The DGE data processing guidelines developed based on this case study produced EgCesA expression profiles in normal wood that were comparable to the profiles of these genes determined with other technologies. A possible alternative splice variant occurring during tension wood formation was identified for the secondary cell wall gene EgCesA3. However future work is needed for the validation of this observation. Early tension wood induction and late tension wood formation was investigated by sampling differentiating xylem from ramets of a Eucalyptus grandis x Eucalyptus urophylla clone induced to form tension wood for 6 hours, 24 hours, 1 week, 2 weeks and 6 months. Up to 2,654 transcripts were found to be significantly differentially expressed during tension wood formation. FLA transcripts were the highest expressed transcripts and were, along with XTH genes, highly up-regulated in early and late tension wood formation. Genes differentially regulated during early tension wood formation reflected a general stress response and hormone signalling pathways. Late tension wood formation was marked by the differential regulation of secondary cell wall biosynthetic genes, which reflected the chemical composition of tension wood. Two secondary cell wall CesA genes were significantly up-regulated, while genes involved in lignin and xylan biosynthesis were significantly down-regulated. Observations suggest that the eucalypt trees used in this study formed tension wood to stabilise the bent stem, while apical dominance was transferred to new side branches which showed signs of extra secondary growth.
Dissertation (MSc)--University of Pretoria, 2011.
Genetics
unrestricted

Adopting a case study approach, this work project focuses on early-stage hybrid organisations in the food waste sector. The purpose of the present study is to investigate which logics the organisations analysed embody, which business models they adopt and which tensions they experience. Four interviews were conducted, compiling three case studies. This work project advances understanding on which logics characterise early-stage hybrids in the food waste sector demonstrating that:food waste organisations embody business and environmental logics; adopt a business model in which customers are part of the beneficiaries; and experience performing, organising and learning tensions.

This dissertation examines social and political tensions in the silver mining city of Potosi during the early decades of the seventeenth century. More specifically, it explores the complex reasons behind a severe outburst of violence among Spaniards of different regional peninsular backgrounds between 1622-25 A slow decline in silver production provides the backdrop to rising tensions during the first several decades of the seventeenth century. The presence of a large, youthful, and restless underclass of young immigrants from Spain exacerbated competition for labor and other resources among silver mining enterprises. The perception that the close-knit, prosperous Basque community of silver miners in Potosi had manipulated the local political scene to their advantage during the early decades of the seventeenth century led to resentment among both the young recent immigrants and those from other regions of Spain who resided in Potosi. Lax oversight and outright venality among royal officials in Potosi exacerbated the hostility and resentment toward the Basques felt by regional groups of Andalusians, Extremadurans, Gallegos, and others. A long-overdue inspection of the royal accounts in Potosi by Contador Alonso Martinez de Pastrana stirred up this already volatile situation and helped precipitate a three-year period of outright violence from 1622-1625 Based on contemporary accounts and archival correspondence, the dissertation provides a detailed overview of this violent period, while focusing on the competing efforts of interested parties to steer events toward a resolution favorable to their faction. Special emphasis is placed on the efforts of the hostile factions to sway both public and official opinion to view the disturbances from their own partisan points-of-view. Such efforts ranged from extensive narrative accounts of the disturbances sent to influential officials to intimidating strong-arm attempts of persuasion. In this same context, the dissertation explores the important connections between the world of theatrical productions in Potosi to the faction hostile to the Basques arguing that theater provided a key persuasive element in convincing some Potosinos to take violent actions against their adversaries
acase@tulane.edu

University-based teacher educators’ first three years on the job are often imbued with tension, as they must renegotiate their professional identities and pedagogical philosophies in relation to ambiguous and sometimes conflicting expectations of what they should do and stand for in this role. As role models for aspiring art teachers, art teacher educators have a powerful influence on their pre-service students’ views of teaching, and on their emergent professional dispositions. However, despite the moral and intellectual significance of their work, and the diversity of their identities and work contexts, research on this population is limited and does not reflect current demographics in the field. While existing studies suggest some of the tensions that art teacher educators—both new and veteran—face on the job, research has not yet explored how new faculty members, specifically, experience their earliest years in the role nor how they learn to develop personally authentic art teacher education pedagogy. This qualitative multi-case study responds to these gaps in the literature, and to the understanding that new knowledge-for-practice is often generated within spaces of creative tension such as career transition. The study participants were eight full-time art education faculty members with less than three years in the role. Individual and cross-case analysis of data collected through semi-structured interviews, qualitative questionnaires, and reflective tasks, revealed that participants’ tensions were predominantly influenced by discrepancies between (1) their established occupational roles/identities and practices, and expectations placed upon them in the art teacher educator role that they had not fully anticipated, and (2) their own, and others’ art-education-related (ideological) values. Most of the participants identified strongly with discipline-specific values (e.g., being grounded in activism and arts-informed social justice). These values functioned as core elements of their professional identities and of their teaching, research, and scholarship. However, in some cases, there were difficulties in translating these values into effective art teacher education pedagogical content knowledge. The data analysis suggested that through reflecting on tensions, participants gained increased professional self-understanding and keener awareness of the forces that enable or constrain the enactment of their personal pedagogical values. Additionally, the data suggest that greater intentional preparation and support for this role (particularly mentorship that validates their established identities and backgrounds) prior to and during the early years, could greatly benefit art teacher educators’ adjustments into the academy and facilitate their building of pedagogical content knowledge for this role.

BACKGROUND: White matter (WM) aberrations have been broadly characterized in schizophrenia using standard diffusion tensor imaging (DTI) techniques. The present study aims to distinguish WM alterations in the early course of schizophrenia using advanced diffusion measures of free-water corrected fractional anisotropy (FAt) and free-water fractional volume (FW), in addition to examining their association with neurocognition, social cognition, and clinical measures. We report baseline results from a longitudinal study investigating the effects of cognitive enhancement therapy (CET) on brain structure and function in schizophrenia. METHODS: The sample consisted of 46 early course schizophrenia patients and 20 healthy controls. Diffusion-weighted images were processed using a free-water imaging pipeline, that separately models diffusion of water in tissue (FAt) and the extracellular space (FW). Tract-Based Spatial Statistics was performed on the FAt and FW diffusion tensor maps and average measures from 24 bilateral regions of interest (ROIs) were extracted. We examined WM structural differences between patients and controls and further investigated WM relations to neurocognition, social cognition, and clinical measures specifically in schizophrenia. RESULTS: Patients showed significant FAt reductions in the body of the corpus callosum, posterior thalamic radiation (PTR), cingulate gyrus, anterior corona radiata, corpus callosum, and corona radiata and FW elevations in the posterior corona radiata (PCR), uncinate fasciculus (UNC), and PTR compared to controls. For patients, positive correlations between FAt and working memory were observed in the PCR and fornix & stria terminalis (FXST). Negative associations between FW and attention/vigilance were observed in the UNC. Positive correlations between FAt and theory of mind (ToM) were observed in average whole-brain and FXST. Negative associations between FW and ToM were observed in average whole-brain and PCR. Positive correlations between FW and negative symptom severity were observed in the external capsule. CONCLUSION: Using free-water imaging, we report WM aberrations and FW elevations in the early course of schizophrenia in addition to neural correlates associated with cognition and clinical measures. Future investigations on the longitudinal effects of CET are warranted for a greater understanding of the underlying neural correlates of clinical manifestations in schizophrenia.
2020-06-14T00:00:00Z

碩士
國立臺灣大學
物理學研究所
104
In the scalar-tensor theory of gravity, the concept of gravitational constant G can be replaced with a scalar field non-minimally coupled to gravity. This turns out to be an additional degree of freedom compared to general relativity and is possible to induce periodic variations (i.e., oscillations) in G by a homogeneous and isotropic massive scalar field. In this thesis, we aim to constrain the rapid oscillation of G. We first show that the equation of motion of the scalar field can be cast into a fairly graceful formula and the dissipation rate of its effective energy density behaves differently in three epochs of cosmic evolution: I. |ΔG/G|~O(1), II. ΔG≪G; 100H≳ν and III. ΔG≪G; 100H<ν , where ν is the frequency of oscillations and H is the cosmic expansion rate. During the Epoch I and Epoch II, the non-minimal coupling and cosmic expansion could lead to non-trivial effects on the dynamics of scalar field, which make the effective energy density dissipate much slower than in the Epoch III. As the universe enters the Epoch III, the effective energy density is in average proportional to a^(-2) or a^(-3) (a is the scale factor), depends on the form and the strength of non-minimal coupling. To be consistent with local experiments on G and the observational cosmology, we find that it is possible to give phenomenological constraints on the effective energy density contributed from G oscillation and the scalar field from the dynamical behavior of the scalar field in both linear and quadratic non-minimal coupling cases. We finally discuss the impact of the constraints on physics in the early universe.

This thesis is comprised of two parts: a Studio Research component with accompanying Exegesis (66%), and a Dissertation (33%). The Dissertation provides the historical theoretical component that informs the Studio Research and Exegesis, entitled The Dingo in the Colonial Imagination.This body of work investigates the tensions between humans and animals that share boundaries. It focuses on the terse relations between humans, dingoes and wild dogs in southeastern Australia. Ideological and practical themes emerged through the studio-based and theoretical research, which spans a range of disciplines including art, science, culture and history. At its core is how humans and undomesticated animals share arbitrary boundaries and suffer the transgression of these boundaries. Primary field research informed the studio and theoretical aspects of the project. It involved consultation with individuals and agencies affected by dingoes and wild dogs in interface zones where private and government managed lands intersect. The 30,000 word dissertation traces colonial visual representations of the Australian native dog during the century that spans early European settlement to Federation. It follows perceptions of the dingo as it is imagined and encountered by European settlers. The dingo's guise ranges from scientific curiosity, object of desire, symbol of wilderness, metaphor for a dying race and as an enemy that threatens the social and economic fabric of the colonial project. The studio work amplifies the influence of these colonial perceptions on contemporary attitudes to dingoes. It follows a trajectory of the disappearing dingo in its representational form, to its implied remnant presence within the farmers' psyche. Early studio work explored a range of materials and practices, encompassing sculptural and drawing strategies, and took its cue from a macabre ritual of animal shaming in remote regional Australia, the so-called 'dog trees', that display the carcasses of one or multiple dingoes and wild dogs. The studio work has culminated in a large-scale sculptural installation, designed to pare back the visual language to its essential elements. This work incorporates the dissolution of the dingo form, which becomes absorbed into the personal objects embedded into the farmers' private territory. The poetic objects that form the final sculptural work presented for examination, Lines of desire, become metaphors for the dingo's capacity to survive and unsettle the rural subconscious.

The autogenous shrinkage due to self-desiccation of high- and ultra-high performance concretes with very low water-cement ratio in case of restraint leads to considerable stresses starting from very early age. The resultant risk of cracking presently cannot be adequately investigated. Parameters that are particularly difficult to capture experimentally are the concrete temperature and the viscoelasticity. The primary objective of this work was to assess as precise as possible the autogenous shrinkage cracking propensity of representative concretes at strong restraint and constant room temperature. Test methods needed to be chosen and enhanced in a way that preferably allowed for the efficient and precise investigation of all relevant factors in the future. Ideally, a method suitable for a complete empirical modeling was provided. First the methodological requirements and the advantages and disadvantages of existing test methods were discussed. Based on this, optimized test methods were proposed. Their suitability was verified using the example of ultra-high strength concrete. The choice of concrete compositions considered the essential measures for reducing shrinkage (internal curing, shrinkage-reducing admixtures, reduction of the fraction of Portland cement in the binder). The autogenous shrinkage was measured with the shrinkage cone method. This new test method was validated by investigations of the repeatability and reproducibility and proved efficient and precise. It allows for measurements under non-isothermal conditions; no established test method exists for that purpose to date. The autogenous shrinkage of the ultra-high strength concretes at the age of 24 h, investigated under quasi-isothermal conditions (20 °C), was between 0,25 mm/m and 0,70 mm/m. It was particularly low when a shrinkage-reducing admixture was added and when superabsorbent polymers were used. The stresses due to restraint were determined with the restrained ring test. A large part of the stresses to be expected according to Hooke’s Law were eliminated by creep and relaxation. The relaxation capacity being very pronounced at very early age was the main reason that no visible cracking occurred, not even with the concretes with high autogenous shrinkage. The development of the autogenous shrinkage cracking propensity was described as ratio of restraint stress and splitting tensile strength. By means of modified ring tests, used to determine the maximum tensile stress, it could be shown that the ratio of stress to strength is an appropriate failure criterion. However, the cracking propensity can be calculated correctly only if the strongly age-dependent ratio of uniaxial to splitting tensile strength is accounted for. Besides, it needs to be considered that at very early age a plastic stress redistribution may occur in restrained ring tests. The reference concrete showed a high cracking propensity of up to 0.68. The fact that shrinkage-reducing measures led to significantly lower values reveals their relevance for the safe application of ultra-high strength concrete. However, the investigations carried out here at 20 °C do not allow for a final assessment of the cracking propensity under typical on-site conditions. To empirically model the autogenous shrinkage cracking propensity as a function of temperature and stress level in the future, an analytical stress solution for non-isothermal restrained ring tests and a new approach for investigating the residual stress and relaxation capacity by means of non-passive restrained ring tests was suggested.:1 Introduction 2 Autogenous shrinkage 5 2.1 Shrinkage and hydration 5 2.2 Definitions and research approaches 10 2.3 Metrological issues 14 2.3.1 Multitude of test methods 14 2.3.2 Time-zero 16 2.3.3 Other metrological issues 18 2.4 Corrugated tube method 19 2.5 Influencing parameters 21 2.5.1 Concrete composition 21 2.5.2 Temperature 23 2.5.3 Specific countermeasures 25 2.6 Summary and conclusions with respect to the own work 25 3 Concretes used in the own investigations 27 3.1 Preliminary remarks 27 3.2 Concrete compositions 27 3.3 Constituents 28 3.3.1 Cement 28 3.3.2 Ground-granulated blast furnace slag 28 3.3.3 Silica fume 28 3.3.4 Admixtures 29 3.3.5 Aggregates 29 3.4 Mixing 29 3.5 Basic properties 30 3.5.1 Compressive strength 30 3.5.2 Splitting tensile strength 31 3.5.3 Modulus of elasticity 33 3.5.4 Analysis of mechanical properties 35 3.5.5 Coefficient of thermal expansion 38 3.5.6 Isothermal calorimetry 39 3.6 Summary 39 4 Shrinkage cone method for measuring autogenous shrinkage 41 4.1 Introduction 41 4.2 Setup and measurement procedure 41 4.3 Temperature control 44 4.4 Precision under quasi-isothermal conditions 47 4.4.1 Repeatability 47 4.4.2 Reproducibility 49 4.4.3 Shrinkage cone method vs. corrugated tube method 49 4.5 Autogenous shrinkage of the investigated concretes at 20 °C 54 4.6 Tests under non-isothermal conditions 55 4.7 Summary 56 5 Stress and cracks due to restrained autogenous shrinkage 58 5.1 Introduction 58 5.2 Degree of restraint 58 5.3 Formation of cracks 60 5.4 Very early age and importance of stress relaxation 63 5.5 Creep and cracking - further methodological aspects 65 5.6 Autogenous shrinkage cracking propensity 69 5.7 Role of temperature history 70 5.8 Further state of knowledge 72 5.8.1 Preliminary remarks on test methods 72 5.8.2 Quantitative investigations under restraint conditions 73 5.8.3 A full-scale model for assessing the cracking risk at very early age 77 5.9 Summary 78 6 Investigation of the autogenous shrinkage cracking propensity 80 6.1 Introduction 80 6.2 Suitability of temperature-stress testing machines 80 6.2.1 Development, setup and use 80 6.2.2 Results of round robin tests 83 6.3 Restrained ring test - methodological foundations 86 6.3.1 Setup and use 86 6.3.2 Evaluation of restrained ring tests 90 6.3.3 Use of temperature changes for the investigation of creep and relaxation 96 6.4 Own investigations with the restrained ring test 97 6.4.1 Setup 97 6.4.2 Compensation of disturbing temperature effects 99 6.4.3 Repeatability 100 6.4.4 Measured steel ring strains 101 6.4.5 Simple stress analysis 102 6.4.6 Autogenous shrinkage cracking propensity - further analysis 106 6.4.7 Thermal stress component 116 6.4.8 Period of maximum cracking propensity 118 6.4.9 Restraint stress versus autogenous shrinkage 119 6.4.10 Cracking propensity versus autogenous shrinkage 120 6.4.11 Further considerations on creep 121 6.5 Summary 126 7 Summary, conclusions and outlook 128 7.1 Summary and conclusions 128 7.2 Outlook 130 8 Literature 131 9 Annex 159
Das durch Selbstaustrocknung verursachte autogene Schwinden von besonders leistungsfähigen Betonen mit sehr niedrigem Wasserzementwert führt bei Dehnungsbehinderung bereits in sehr frühem Alter zu erheblichen Zwangsspannungen. Die Gefahr der Rissbildung, die sich daraus ergibt, lässt sich bislang nur unzureichend untersuchen. Experimentell besonders schwer zu erfassende Faktoren sind die Betontemperatur und die Viskoelastizität. Das vorrangige Ziel der Arbeit war die möglichst genaue Ermittlung der autogenen Schwindrissneigung repräsentativer Betone bei starker Dehnungsbehinderung und konstanter Raumtemperatur. Dabei waren die Prüfverfahren möglichst so zu wählen und weiterzuentwickeln, dass sich zukünftig alle relevanten Faktoren effizient und genau untersuchen lassen. Im Idealfall sollte eine Methode entstehen, die eine vollständige empirische Modellierung erlaubt. Zunächst wurden die methodischen Anforderungen und die Vor- und Nachteile existierender Prüfverfahren diskutiert. Darauf aufbauend wurden optimierte Verfahren vorgeschlagen. Ihre Eignung wurde an ultrahochfestem Beton überprüft. Bei der Auswahl der Betone wurden die wesentlichen Maßnahmen zur Schwindreduzierung berücksichtigt (innere Nachbehandlung, schwindreduzierende Zusatzmittel, Verringerung des Portlandzementanteils am Bindemittel). Das autogene Schwinden wurde mit dem Schwindkegelverfahren gemessen. Das neue Verfahren wurde durch Untersuchungen zur Wiederhol- und Vergleichsgenauigkeit validiert und erwies sich als effizient und genau. Es ermöglicht Messungen unter nicht-isothermen Bedingungen; hierfür existiert bisher kein etabliertes Verfahren. Das autogene Schwinden der untersuchten ultrahochfesten Betone unter quasi-isothermen Bedingungen (20 °C) betrug im Alter von 24 h zwischen 0,25 mm/m und 0,70 mm/m. Besonders gering war es bei Zugabe eines schwindreduzierenden Zusatzmittels bzw. Verwendung superabsorbierender Polymere. Mit dem Ring-Test wurden die bei Dehnungsbehinderung entstehenden Spannungen ermittelt. Ein großer Teil der gemäß Hooke’schem Gesetz zu erwartenden Spannungen wurde durch Kriechen und Relaxation abgebaut. Die im sehr frühen Alter stark ausgeprägte Relaxationsfähigkeit war der wesentliche Grund dafür, dass es selbst bei Betonen mit hohem autogenen Schwinden zu keiner erkennbaren Rissbildung kam. Die Entwicklung der autogenen Schwindrissneigung wurde als Verhältnis von Zwangsspannung und Spaltzugfestigkeit beschrieben. Durch modifizierte Ring-Tests, mit deren Hilfe die maximale Zugspannung ermittelt wurde, konnte gezeigt werden, dass das Verhältnis von Spannung und Festigkeit als Versagenskriterium geeignet ist. Die Rissneigung lässt sich aber nur dann korrekt berechnen, wenn das stark altersabhängige Verhältnis von einaxialer Zugfestigkeit und Spaltzugfestigkeit berücksichtigt wird. Außerdem ist zu beachten, dass es im sehr frühen Alter zu einer plastischen Spannungsumlagerung in Ring-Tests kommen kann. Der Referenzbeton wies eine hohe Rissneigung von bis zu 0,68 auf. Dass die schwindreduzierenden Maßnahmen zu deutlich geringeren Werten führten, zeigt deren Bedeutung für den sicheren Einsatz von ultrahochfestem Beton. Die hier bei 20 °C durchgeführten Untersuchungen erlauben allerdings keine abschließende Bewertung der Rissneigung unter baustellentypischen Bedingungen. Um die autogene Schwindrissneigung zukünftig als Funktion der Temperatur und des Lastniveaus empirisch modellieren zu können, wurden eine analytische Spannungslösung für nicht-isotherme Ring-Tests und ein neuer Ansatz zur Untersuchung der Resttrag- und Relaxationsfähigkeit mit Hilfe nicht-passiver Ring-Tests vorgeschlagen.:1 Introduction 2 Autogenous shrinkage 5 2.1 Shrinkage and hydration 5 2.2 Definitions and research approaches 10 2.3 Metrological issues 14 2.3.1 Multitude of test methods 14 2.3.2 Time-zero 16 2.3.3 Other metrological issues 18 2.4 Corrugated tube method 19 2.5 Influencing parameters 21 2.5.1 Concrete composition 21 2.5.2 Temperature 23 2.5.3 Specific countermeasures 25 2.6 Summary and conclusions with respect to the own work 25 3 Concretes used in the own investigations 27 3.1 Preliminary remarks 27 3.2 Concrete compositions 27 3.3 Constituents 28 3.3.1 Cement 28 3.3.2 Ground-granulated blast furnace slag 28 3.3.3 Silica fume 28 3.3.4 Admixtures 29 3.3.5 Aggregates 29 3.4 Mixing 29 3.5 Basic properties 30 3.5.1 Compressive strength 30 3.5.2 Splitting tensile strength 31 3.5.3 Modulus of elasticity 33 3.5.4 Analysis of mechanical properties 35 3.5.5 Coefficient of thermal expansion 38 3.5.6 Isothermal calorimetry 39 3.6 Summary 39 4 Shrinkage cone method for measuring autogenous shrinkage 41 4.1 Introduction 41 4.2 Setup and measurement procedure 41 4.3 Temperature control 44 4.4 Precision under quasi-isothermal conditions 47 4.4.1 Repeatability 47 4.4.2 Reproducibility 49 4.4.3 Shrinkage cone method vs. corrugated tube method 49 4.5 Autogenous shrinkage of the investigated concretes at 20 °C 54 4.6 Tests under non-isothermal conditions 55 4.7 Summary 56 5 Stress and cracks due to restrained autogenous shrinkage 58 5.1 Introduction 58 5.2 Degree of restraint 58 5.3 Formation of cracks 60 5.4 Very early age and importance of stress relaxation 63 5.5 Creep and cracking - further methodological aspects 65 5.6 Autogenous shrinkage cracking propensity 69 5.7 Role of temperature history 70 5.8 Further state of knowledge 72 5.8.1 Preliminary remarks on test methods 72 5.8.2 Quantitative investigations under restraint conditions 73 5.8.3 A full-scale model for assessing the cracking risk at very early age 77 5.9 Summary 78 6 Investigation of the autogenous shrinkage cracking propensity 80 6.1 Introduction 80 6.2 Suitability of temperature-stress testing machines 80 6.2.1 Development, setup and use 80 6.2.2 Results of round robin tests 83 6.3 Restrained ring test - methodological foundations 86 6.3.1 Setup and use 86 6.3.2 Evaluation of restrained ring tests 90 6.3.3 Use of temperature changes for the investigation of creep and relaxation 96 6.4 Own investigations with the restrained ring test 97 6.4.1 Setup 97 6.4.2 Compensation of disturbing temperature effects 99 6.4.3 Repeatability 100 6.4.4 Measured steel ring strains 101 6.4.5 Simple stress analysis 102 6.4.6 Autogenous shrinkage cracking propensity - further analysis 106 6.4.7 Thermal stress component 116 6.4.8 Period of maximum cracking propensity 118 6.4.9 Restraint stress versus autogenous shrinkage 119 6.4.10 Cracking propensity versus autogenous shrinkage 120 6.4.11 Further considerations on creep 121 6.5 Summary 126 7 Summary, conclusions and outlook 128 7.1 Summary and conclusions 128 7.2 Outlook 130 8 Literature 131 9 Annex 159

Summaries in Afrikaans and English
Text in Afrikaans
Die tema van hierdie studie toon die kerkbegrip van Cyprianus aan as 'n spanning tussen die kerk as instituut en die kerk van die Gees. Hoofstuk een skets die invloed van Tertullianus as leermeester op Cyprianus. Tertullianus se kerkbegrip getuig self van spanning wat die produk is van 'n verandering van lidmaatskap vanaf die Katolieke kerk na die Montaniste. Tertullianus se kerkbegrip word vanuit twee perspektiewe belig. Eerstens vanuit 'n Katolieke, met 'n fokus op die fundering van die ware kerk en die mag van die kerk om sondes te kan vergewe. Tweedens vanuit 'n Montanistiese, wat die def iniering van die ware kerk en die mag van die kerk om sondes te kan vergewe eksklusief geestelik begrond. Hoofstuk twee skets die milieu waarbinne Cyprianus gearbei het. Dit sluit in 'n biografie van Cyprianus en die Afrika-religie en bevolking. Tweedens word die Europese invloed op Cyprianus se kerkbegrip aangedui. Die invloed van die Romeinse staatkundige model kan duidelik waargeneem word. Die grootste invloed was egter die Roomse kerklike model, weens die dinamika van die Roomse kerk. Hoofstuk drie skets die ekklesiologie van Cyprianus. Die spanning tussen die kerk as 'n instituut en die kerk van die Gees word aangedui deur 'n bespreking van die episkopaat; die betekenis van die biskop; Cyprianus se gesagsbegrip en sy perspektief op die primaat. Cyprianus se Bybelse verbintenis, sowel as die twee historiese lyne, naamlik die Pauliniese lyn en die Petruslyn, plaas sy uitspraak salus extra ecclesiam non est in perspektief. Cyprianus se kerkbegrip is primer 'n ekklesiologie van die Gees. In sy strewe na die eenheid van die kerk vind hy die kerk as instituut egter onontbeerlik. Spanning onstaan in sy poging om 'n sintese tussen die twee te vorm.
The theme of this study reveals the tension to be found between the church as institution and the church of the Spirit, in the ecclesiology of Cyprian. Chapter one shows the influence which Tertullian, as tutor, exerted on Cyprian. The ecclesiology of Tertullian also reveals the tension which is produced by the change of membership from Catholicism to Montanism. Tertullian's ecclesiology is highlighted from two different perspectives. Firstly from a Catholic view, with the focus on the fundamentals of the true church, and the authority and power of the church to forgive sins. Secondly, a Montanist view is proposed, which defines the true church, and the power it yields in forgiving sins, as being exclusively spiritual in nature. Chapter two describes the environment in which Cyprian worked. This includes a biography of Cyprian, as well as the African religion and people. Secondly the European influence is shown on Cyprian's ecclesiology. The influence exerted by the Roman state model is also clearly seen. The major influence though, was exercised by the Roman church model, on account of the dynamics of the Roman church. Chapter three describes Cyprian's ecclesiology. The tension between the church as institute and the church of the Spirit is revealed in a discussion on the episcopacy; the significance of the bishop; Cyprian's view on authority and his perspective on the primacy. Cyprian's biblical connection, as well as the two historical lines, namely the Pauline and Petrine lines, put his salus extra ecclesiam non est pronouncement in perspective. ecclesiology the unity of Cyprian's view is primarily that of a of the Spirit. In his striving towards the church though, he finds the church as institute to be indispensable. Tension develops in his endeavor to form a synthesis between the two.
Christian Spirituality, Church History and Missiology
D. Th.