京都大学 / 新制・課程博士 / 博士(工学) / 甲第23920号 / 工博第5007号 / 新制||工||1781(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 大内 誠, 教授 大塚 浩二 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2009.

Video compression is the process of reducing the amount of data required to represent digital video while preserving an acceptable video quality. Recent studies on video compression have focused on multimedia transmission, videophones, teleconferencing, high definition television (HDTV), CD-ROM storage, etc. The idea of compression techniques is to remove the redundant information that exists in the video sequences. Motion compensated predictive coding is the main coding tool for removing temporal redundancy of video sequences and it typically accounts for 50-80% of the video encoding complexity. This technique has been adopted by all of the existing international video coding standards. It assumes that the current frame can be locally modelled as a translation of the reference frames. The practical and widely method used to carry out motion compensated prediction is block matching algorithm. In this method, video frames are divided into a set of non-overlapped macroblocks; each target macroblock of the current frame is compared with the search area in the reference frame in order to find the best matching macroblock. This will carry out displacement vectors that stipulate the movement of the macroblocks from one location to another in the reference frame. Checking all these locations is called full Search, which provides the best result. However, this algorithm suffers from long computational time, which necessitates improvement. Several methods of Fast Block Matching algorithm were developed to reduce the computation complexity. This thesis focuses on two classifications: the first is called the lossless block matching algorithm process, in which the computational time required to determine the matching macroblock of the full search is decreased while the resolution of the predicted frames is the same as for the full search. The second is called the lossy block matching algorithm process, which reduces the computational complexity effectively but the search result’s quality is not the same as for the full search.

Este trabalho apresenta uma análise sobre um novo método de formação de imagem, utilizando aparelhos de ultra-som a elastografia. Esta técnica baseia-se no fato de que quando um meio elástico, como o tecido, é deformado por uma tensão constante e uniaxial, todos os pontos no meio possuem um nível de deformação longitudinal cujo componente principal está ao longo do eixo de deformação. Se elementos do tecido possuem um módulo elástico diferente dos demais, a deformação nestes elementos será relativamente maior ou menor. Elementos mais rígidos geralmente deformam-se menos. Desta forma, pode-se mapear e identificar estruturas com diferentes níveis de dureza. A comparação entre os mapas de RF de pré e pós-deformação foi realizada pela técnica de block matching. Esta técnica consiste em comparar regiões, ou kernels, no mapa de pré-deformação com regiões de mesmo tamanho no mapa de pós-deformação. Esta comparação é feita pela minimização de uma função custo. Nesta técnica, o tamanho do kernel, é um dos principais parâmetros para melhorar a precisão das medidas de deslocamento. O principal objetivo neste trabalho é aperfeiçoar o algoritmo de block matching visando melhorar a precisão da determinação de deslocamento em técnicas de deformação dinâmica e estática, mantendo o custo computacional baixo. Para isto, foram utilizados phantoms com e sem inclusões mais duras que o meio. Os phantoms foram submetidos a deformações estáticas e dinâmicas. Foi possível determinar o comportamento destes phantoms sob estas formas de deformação, e as faixas de kernel e funções custo que forneceram os melhores resultados. Também foram gerados elastogramas do phantom com inclusão. Estas imagens permitiram avaliar a influência dos diferentes kernels sobre a resolução dos elastogramas e a capacidade em diferenciar a lesão do tecido circundante. Comparando os elastogramas obtidos sobre deformação dinâmica, utilizando os kernels que apresentaram o melhor desempenho, com as respectivas imagens em modo B, pôde-se observar que a inclusão estava clara e bem delimitada. / This work provides an analysis about a new method for image formation using ultrasound devices elastography. This technique is based on the fact that when an elastic medium, as the tissue, is deformed under a constant and directional stress, all the points in the medium have a deformation level whose main component is along the deformation axis. If tissues elements have different elastic modules, the deformation in these elements will be higher or lower. Normally harder elements have lower deformations. In this way, one can detect and identify structures with different elastic levels. The comparisons between the pre and post-deformation RF maps were done by the block matching technique. This technique is based on the comparison of regions, or kernels, in the pre-deformation maps with regions of the same size in the post-deformation map. This is done by the minimization of a cost function. In this technique, the kernel size is one of the most important parameters to obtain better resolution and precision in the displacement measurements. The goal of this work is to optimize the block matching algorithm to improve the displacement estimates precision in both dynamic and static deformations, while keeping a low computational cost. To obtain this, we used phantoms with and without inclusions harder than the medium. These phantoms were submitted to both static and dynamic deformations. It was possible to estimate the behavior of these phantoms under these deformations, and the kernel range and cost functions that provided the best results. Also, we generated the elastograms of the phantom with the inclusion. These images allowed us to evaluate the influence of the different kernel sizes under the elastograms resolution and their capability in differentiate the lesion from the embedding tissue. Comparing the elastograms obtained under dynamic deformation that had the best performance, with the B mode images, we could conclude that the inclusion was well delimited and clear.

La transcription de l’ADN en ARN constitue la première étape de l’expression d’un gène. Durant les dix dernières années, plusieurs études ont montré qu’environ 80-90% du génome est transcrit et que la transcription peut démarrer presque partout. Ce phénomène, connu sous le nom de transcription envahissante, représente une menace sérieuse contre l’expression correcte du génome car il peut interférer non seulement avec d’autres évènements de transcription mais également avec n’importe quel procédé impliquant l’ADN. Une terminaison sélective est donc un mécanisme de la plus haute importance pour la stabilité du génome et la correcte régulation de l’expression des gènes. Ici nous décrivons la terminaison road-block, un nouveau mécanisme de la terminaison par l’ARN polymerase II, qui a pour fonction de limiter la transcription envahissante et de limiter les conséquences d’une translecture au niveau des sites de terminaison canoniques de S.cerevisiae. Nous démontrons également que plusieurs facteurs de transcription peuvent entrainer cette terminaison et que certains sites génomiques y sont associés. De plus, nous explorons également la possibilité que ces terminaisons road-block puissent contribuer à rendre spécifiques les origines de réplication. / Transcription of DNA into RNA intermediates constitutes the first step in gene expression. During the last decade, several studies showed that about 80-90% of the genome is transcribed, and that transcription can initiate almost anywhere. This process—known as pervasive transcription—represents a serious threat to proper gene expression as it has the potential to interfere with not only other transcription events, but any DNA-based process. Selective transcription termination is therefore a mechanism of paramount importance for genome transcriptome stability and correct regulation of gene expression. Here we describe road-block termination, a novel termination mechanism for RNA polymerase II that functions to limit pervasive transcription and buffer the consequences of readthrough transcription at canonical terminators in S.cerevisiae. We show that several transcription factors can elicit this termination and that a number of unexpected genomic loci are associated with it. Additionally, we explore the possibility that road-block termination might contribute to specification of replication origins.

The topic of this thesis is temporal logical inference in atemporal models of time. The thesis presents a branching logic with observers for the purpose of this investigation. A series of theorems rigorously demonstrate that temporal reasoning is possible also in an atemporal world. 1

Polylactide (PLA) is a biodegradable and biocompatible polymer which is attracting much attention for environmental issues imposed by the petroleum-based polymers. PLA can be used as medical polymer in surgical sutures, implants tissue and many other areas. However, one of the main shortcomings of PLA is its brittleness in nature and relatively poor mechanical properties, which often limits its further application. It is generally accepted for polymeric materials that some mechanical properties of oriented structures can be improved as the molecular weight of PLA increases. The outcome of this thesis will provide the knowhow to achieve ultrahigh molecular weight of polylactides, and further to improve the mechanical properties and extend its range of applications. In this work, different catalytic systems for the synthesis of ultra-high molecular weight (UHMW) polylactide are considered. For the catalytic systems considered, the reaction conditions and initiators are investigated. The resulting molecular characteristics and mechanical properties of the synthesized polymers will be evaluated. On the contrary to the brittle nature of PLA, Poly(ε-carprolactone) (PCL) is elastic and flexible with a relatively low melting point (60 oC) and low glass transition temperature (-60 oC). Hence, ultra-high molecular weight PCL will be also synthesized by using the same catalytic systems employed for achieving UHMWPLAs. PCL is also used in different biomedical applications, such as in scaffolds for tissue engineering. It is well documented that the complementary physical properties of PLA and PCL have the potential to enhance toughness of PLA. To enhance the toughness and mechanical properties of the block copolymers attempt is made to synthesize ultra-high molar mass of the two polymers in the block copolymer. But their molar masses (and consequently their mechanical properties) are always on the low side. For this reason, the synthesis of high molecular mass PLA and PCL multiblocks will be attempted. Furthermore, it is interesting to study the synthesis of high molar masses PLLA and PDLA stereoblocks especially their ability to crystallize during the polymerization and test the possibility to prepare stereocomplex only during synthesis. The resulting molecular characteristics and mechanical properties of the synthesized multiblock-polymers will be also evaluated.

No description available.

We know that the best linear combination of the intra- and inter-block estimates is Intra-estimatexInter-variance+Inter-estimatexIntra-variance / Intra-variance + Inter-variance ; however, this combined estimate is merely theoretical, since we do not know in practice the exact inter- and intra-variances. A reasonable solution is to use a random weight which can be computed from the data of our experiment, but so far there has been no practical solution without severe restrictions on the size of the experiment, and no solution at all for a clear answer to the question of how much we recovered. In fact, the experimenter applying the methodology available to him now, cannot be sure that he is really improving the accuracy of his estimation. This research has achieved the following: 1. A new method of combining two independent estimates has been developed. This method has its use in incomplete block designs, in similar experiments, and in randomized block designs with heterogeneous variances. The improvement introduced by this method is very satisfactory, compared with the utmost possible theoretical improvement. 2. A procedure for recovering the inter-block information in B.I.B. designs was given, which is applicable in experiments as small as t = 4. 3. It has been proven that the practical utilization of inter-block information is possible in any P.B.I.B. with seven treatments or more. 4. A general procedure for recovering the inter-block information in P.B.I.B.'s with two associate classes was given. 5. An inter-block analysis of singular and semi-regular group divisible designs was discussed, which makes a partial utilization of the inter-information possible. In general, this work has two merits: 1. It makes possible the utilization of the interblock information in small and moderate size experiments. 2. As a ratio of the utmost possible theoretical recovery (by combining linearly), either exactly or a lower bound of the ratio of recovery is always computable. Tables which enable the experimenter to use the procedures described in this dissertation were given. The ratios of recovery listed in these tables show that the new method gives good results where the old method is not applicable, and when the old method starts, hopefully, to be valid, the ratio of recovery achieved by the new method starts to approach the theoretical value that can be achieved, assuming the intra- and inter-variance are known. / Ph. D.

The work of Kramer and Bradley on the use of factorials in incomplete block designs bas been extended to permit both the intra-block and combined intra- and inter-block analyses of factorials in balanced and partially balanced incomplete block designs. In particular, we have obtained a combined intra- and inter-block analysis for factorials in balanced incomplete block designs, group divisible designs, and Latin Square types of partially balanced, incomplete block designs. For the class of Latin Square sub-type L₃ designs both the intra-block and combined intra- and inter-block analyses have been developed. In general, factorial treatment combinations were assigned to the association schemes by permitting the rows of the association schemes to represent the levels of one factor and the columns to represent the levels of a second factor. The extension to multifactor factorials was then carried out by sub-dividing the levels of the basic two-factor factorial, the levels in the sub-divisions representing the levels of the multi-factor factorials. Estimators for the factorial effects have been obtained along with their variances and covariances. Sums of squares in terms of the factorial estimators have been derived and can be used to carry out tests of significance. These sums of squares were shown, for the combined intra- and inter-block analyses, to be independently distributed as χ²-variates with the appropriate numbers of degrees of freedom. Suitable sums of squares for tests of significance are not possible in general for Latin Square sub-type L₃ designs. In situations such as these, we can only consider contrasts among the estimators and use their variances to perform tests of significance. However, for the special cases of factorials in the 4 x 4 Latin Square sub-type L₃ design, a complete analysis yielding the adjusted sums of squares for the factorial effects is possible if the factorial treatments are applied to the association scheme in a different manner. Single-degree-of-freedom contrasts are obtained in much the usual way as for factorials in complete block designs. The method of incorporating a fractional replicate of a factorial into incomplete block designs is also considered. Numerical examples have been worked in detail for a group divisible design and a Latin Square sub-type L₂ design. The procedure for analyzing a Latin Square sub-type L₃ design is also discussed. / Ph. D.