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Upper and lower bound theorems of limit analyses have been presented in part I of the paper. Part II starts with the finite element discretization of these theorems and demonstrates how both can be combined in a primal–dual optimization problem. This recently proposed numerical method is used to guide the development of a new class of closed-form limit loads for circumferential defects, which show that only large defects contribute to plastic collapse with a rapid loss of strength with increasing crack sizes. The formulae are compared with primal–dual FEM limit analyses and with burst tests. Even closer predictions are obtained with iterative limit load solutions for the von Mises yield function and for the Tresca yield function. Pressure loading of the faces of interior cracks in thick pipes reduces the collapse load of circumferential defects more than for axial flaws. Axial defects have been treated in part I of the paper.
Spontaneous language has rarely been subjected to neuroimaging studies. This study therefore introduces a newly developed method for the analysis of linguistic phenomena observed in continuous language production during fMRI.
Most neuroimaging studies investigating language have so far focussed on single word or — to a smaller extent — sentence processing, mostly due to methodological considerations. Natural language production, however, is far more than the mere combination of words to larger units. Therefore, the present study aimed at relating brain activation to linguistic phenomena like word-finding difficulties or syntactic completeness in a continuous language fMRI paradigm. A picture description task with special constraints was used to provoke hesitation phenomena and speech errors. The transcribed speech sample was segmented into events of one second and each event was assigned to one category of a complex schema especially developed for this purpose. The main results were: conceptual planning engages bilateral activation of the precuneus. Successful lexical retrieval is accompanied – particularly in comparison to unsolved word-finding difficulties – by the left middle and superior temporal gyrus. Syntactic completeness is reflected in activation of the left inferior frontal gyrus (IFG) (area 44). In sum, the method has proven to be useful for investigating the neural correlates of lexical and syntactic phenomena in an overt picture description task. This opens up new prospects for the analysis of spontaneous language production during fMRI.
Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used.
Thin films of poly(ethyleneterephthalate) [PET]were exposed to radiation dose ranging from 10 to 30 kGy by using gamma rays in the range 12.8-177.8 MGy using swift light ions of hydrogen. There was no effect of the radiation dose on the optical behaviour of PET as a result of exposure to radiation dose up to 30 kGy brought about by gamma rays but a significant decrease in the optical band gap values was observed when PET was exposed to swift light ions of hydrogen. The data obtained are discussed in terms of optical studies carried out on PET using swift heavy ions.
Compared with rodents and many other animal species, the human cytochrome P450 (P450) Cyp2c gene cluster varies significantly in the multiplicity of functional genes and in the substrate specificity of its enzymes. As a consequence, the use of wild-type animal models to predict the role of human CYP2C enzymes in drug metabolism and drug-drug interactions is limited. Within the human CYP2C cluster CYP2C9 is of particular importance, because it is one of the most abundant P450 enzymes in human liver, and it is involved in the metabolism of a wide variety of important drugs and environmental chemicals. To investigate the in vivo functions of cytochrome P450 Cyp2c genes and to establish a model for studying the functions of CYP2C9 in vivo, we have generated a mouse model with a deletion of the murine Cyp2c gene cluster and a corresponding humanized model expressing CYP2C9 specifically in the liver. Despite the high number of functional genes in the mouse Cyp2c cluster and the reported roles of some of these proteins in different biological processes, mice deleted for Cyp2c genes were viable and fertile but showed certain phenotypic alterations in the liver. The expression of CYP2C9 in the liver also resulted in viable animals active in the metabolism and disposition of a number of CYP2C9 substrates. These mouse lines provide a powerful tool for studying the role of Cyp2c genes and of CYP2C9 in particular in drug disposition and as a factor in drug-drug interaction.
In current clinical cardiovascular MR (CMR) practice cardiac motion is commonly dealt with using ECG based synchronization. However, ECG is corrupted by magneto-hydrodynamic (MHD) effects in magnetic fields. This leads to artifacts in the ECG trace and evokes severe T-wave elevations, which might be misinterpreted as R-waves resulting in erroneous triggering. At (ultra)high field strengths, the propensity of ECG recordings to MHD effects is further pronounced. Pulse oximetry (POX) being inherently sensitive to blood oxygenation provides an alternative approach for cardiac gating. However, due to the travel time of the blood the peak of maximum oxygenation and hence the trigger is delayed by approx. 300 ms with respect to the ECG's R-wave. Also the peak of maximum oxygenation shows a jitter of up to 65 ms. Alternative triggering approaches include acoustic cardiac triggering (ACT). In current clinical practice cardiac gating / triggering commonly relies on using single physiological signals only. Realizing this limitation this study proposes a combined triggering approach which exploits multiple physiological signals including ECG, POX or ACT to track cardiac activity. The feasibility of the coupled approach is examined for LV function assessment at 7.0 T. For this purpose, breath-held 2D-CINE imaging in conjunction with cardiac synchronization was performed paralleled by real time logging of physiological waveforms to track (mis)synchronization between the cardiac cycle and data acquisition. Combinations of the ECG, POX and ACT signals were evaluated and processed in real time to facilitate reliable trigger information.
In the introduction to their book "What is philosophy?" Gilles Deleuze and Felix Guattari deplore the inflationary and trivialised use of the term concept: "Finally, the most shameful moment came when computer science, marketing, design and advertising, all the disciplines of communication, seized hold of the word concept itself and said: 'This is our concern, we are the creative ones, we are the ideas men! We are the friends of the concept, we put in our computers.' " This doctoral thesis shares the concern of Gilles Deleuze and Felix Guattari, but still, it is a thesis in architecture and thus collocated within the field of the representatives of the "ideas men". It engages in architectural design theory, and refers in particular to the investigation of methodological approaches within the design process. Therefore, the thesis will not contribute to the philosophical dimension of the term, but intends to overcome its imprecise use within the architectural discourse, in compliance with Eugène Viollet-le-Duc's admonition relative to vague definitions: "Dans les arts, et dans l'architecture en particulier, les définitions vagues ont causé bien des erreurs, ont laissé germer bien des préjugés, enraciner bien des idées fausses. On met un mot en avant, chacun y attache un sens différent." The term concept in architecture is very often used as pure marketing collateral, it serves to sell an idea, a product, a design. Its functional applicability is reduced to a special manner of illustration, produced as one of the various design presentation documents at the end of the design process. In contrast, the original contribution of this thesis aims to give a precise, instrumental dimension to the term concept: the concept is the expression of a specific logic, capable to guide the decisional sequences of the process and thus to improve the quality of the designed projects. The motivation to define a specific instrumentality of the concept is closely connected to the issue of interdisciplinarity in the architects’ profession. The interdisciplinary character of the architectural field is widely accepted and discussed as such, but the thesis intends to give a more precise definition of the various kinds of competences involved by classifying them into either the internal or the external group. The traditional notion of interdisciplinarity, predominantly seen as collaboration between architects and technical experts, and, most notably, the historical, sometimes contentious, relationship between architects and engineers is described. Referring to recent developments, the transformation of the architect’s role within the professional sphere, marked by an increasing importance of diverse influences and linked to a growing risk of marginalisation, is illustrated. The thesis describes different ways to adapt to this specific kind of interdisciplinarity, which generally requires the architect’s ability to connect and to integrate various contents, different points of view and diverse scales. On the other hand, the big potential which is implicit in the interdisciplinary field is exposed: architects can inform their core competence, the design, by extracting contents of different disciplinary competences, pertaining or not pertaining to their own professional field. They have the possibility to cross fields of external competences in a selective way and by doing so they can build up a corpus of knowledge capable to generate and communicate guidelines and systematic methodologies for their design. At the end, the analysis of these two aspects allows the definition of a more specific professional profile of the architect as specialist of interdisciplinarity. The thesis is concerned with the theories around the design process. The design process is seen as open to inspection and critical evaluation, with major focus on the decisional sequences which characterise it. It concentrates on the process’ descriptiveness and the degree of self-conscious approaches applied within it. The importance of regulative, strategic mechanisms is illustrated by testimonies taken from a series of design researches and leads to the functional definition of the figure of the concept as representation of a coherent set of ideas, as generator of a project-specific system of rules and as communicator of decisional strategies. The concept's function is furthermore defined as communicative interface which generates and transmits the system of rules authoritative for all the disciplinary competences involved in the design process, a communicative interface which constitutes a basis of shared convictions capable to increase the efficiency of collaboration. Furthermore, the concept's capacity to explore and elaborate the contents of external disciplines is identified as a possible methodological approach to innovative design thinking. The approach to a specific functional definition of the concept is continued by the description of a series of instruments that are simultaneously generating and communicating it. It is outlined to which degree the concept itself is already the result of an ideational process, collocated within the initial phase of the design proceedings, serving as a guideline to them, but still continuously evolving and adapting in its progression. In addition, it is illustrated how all the diverse instruments of the concept are operational media through which the knowledge transition between different disciplines can occur. The considerations about the concept as operational instrument of design are elaborated with regard to a number of examples of didactical applications that are particularly involved in the development and teaching of specific design methods. These examples illustrate the interrelations between design theory and design education. They are derived from very different schools of architecture and diverse mindsets, but all of them transmit models of conceptual design thinking.