Thesis (Ph. D.)--University of Chicago, 2002. / "December 2002." Includes bibliographical references (p. 152-159). Also available on the Internet.

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It has been realised in the GIS community that most 2D GISs are capable of handling 2D spatial data efficiently, but systems have had less success with 3D spatial data. This is reflected in the current GIS market place where systems which can handle 3D data are hardly available - due to several impediments in implementing such systems. This thesis attempts to address some of the impediments. The impediments which related to spatial data especially data representation, data structuring and data modelling using object-oriented (OO) techniques are the foci of this thesis. OO techniques are utilized because they offer several advantages over the traditional (i.e. structural) techniques in software development. In the aspect of spatial representation, several major representations are investigated, which then lead to identifying an appropriate representation both for 2D and 3D, that is triangular irregular network (TIN) data structures. 2D data is represented by a 2D TIN, and 3D data is represented by a 3D TIN (also called a tetrahedral network or TEN). Several algorithms were developed for the construction of the data structures where procedures such as distance transformation (DT) and Voronoi tessellations were utilized. Besides standard Delaunay triangulations, constrained triangulations were also developed, thus the inclusion of real world objects in the spatial data modelling can be facilitated. Four classes of real world objects are identified (i.e., point, line, surface, and solid objects). For the purpose of spatial data modelling of the four types of objects, a formal data structure (FDS) is utilized.

This thesis is concerned with the 2D and 3D mathematical modelling of satellite-based linear array stereo images and the implementation of this modelling in a general adjustment program for use in sophisticated analytically-based photogrammetric systems. The programs have also been used to evaluate the geometric potential of linear array images in different configurations for medium scale topographic mapping. In addition, an analysis of the information content that can be extracted for topographic mapping purposes has been undertaken. The main aspects covered within this thesis are: - 2D mathematical modelling of space linear array images; - 3D mathematical modelling of the geometry of cross-track and along-track stereo linear array images taken from spacebome platforms; - the algorithms developed for use in the general adjustment program which implements the 2D and 3D modelling; - geometric accuracy tests of space linear array images conducted over high-accuracy test fields in different environments; - evaluation of the geometric capability and information content of space linear array images for medium scale topographic mapping; This thesis concludes that the mathematical modelling of the geometry and the adjustment program developed during the research has the capability to handle the images acquired from all available types of space linear array imaging systems. Furthermore it has been developed to handle the image data from the forthcoming very high-resolution space imaging systems utilizing flexible pointing of their linear array sensors. It also concludes that cross-track and along-track stereo images such as those acquired by the SPOT and MOMS- 02 linear array sensors have the capability for map compilation in 1:50,000 scales and smaller, but only in conjunction with a comprehensive field completion survey to supplement the data acquired from the satellite imagery.

<p>Bioactive gibberellins (GAs) are phytohormones with various effects on plant development, from seed germination through fruit development. The signaling pathway of GA is centered on DELLA proteins (DELLAs), a group of growth repressors degraded upon perception of GA. Previous studies demonstrated that DELLAs administrate global regulation of gene expression. However, given that DELLAs do not contain any canonical DNA-binding domain and that DELLAs only have a moderate association to their target promoters, the nuclear-localized DELLAs are believed to interact with transcription factors for function. Indeed, quite a few transcription factors have been identified as DELLA interactors in the plant model Arabidopsis thaliana, some of which are well-known downstream transcription regulators involved in other signaling pathways. Nevertheless, the molecular mechanisms how DELLAs inhibit so many aspects of plant growth cannot be fully explained by the known DELLA interactors. </p><p>Recently, our lab discovered that INDETERMINATE DOMAIN 1 (IDD1), a C2H2 zinc-finger protein in Arabidopsis, and its closest homolog IDD2, have a strong physical interaction with DELLAs, revealing the potential involvement of these two IDD genes in GA signaling. Hence, the objectives of my doctoral research are (1) to evaluate the roles of IDD1 and IDD2 in GA-responsive phenotypes, (2) to investigate the genetic interaction between IDD1, IDD2 and DELLAs and (3) to identify the function of IDD1 and IDD2 and the significance of IDD-DELLA interaction in transcriptional regulation of IDD/DELLA targets. First, we found that both IDDs redundantly promote GA-induced hypocotyl elongation, and that they also play a positive role in stem elongation and floral initiation. Secondly, epistasis analyses exhibit that REPRESSOR OF ga1-3 (RGA) and GA INSENSITIVE (GAI), two DELLAs with a predominant role in vegetative growth, antagonize IDD1 and IDD2 in hypocotyl elongation, and that GAI also opposes IDD2 in stem elongation and floral initiation. These results entail an antagonistic relationship between IDDs and DELLAs via protein-protein interaction. We then showed that IDD1 and IDD2 repress the expression of canonical DELLA direct targets, including GA20ox2, GA3ox1, GID1b and SCL3. IDD1 also inhibits transcription of CAPRICE (CPC) and GLABRA2 (GL2), two crucial regulators of root epidermal cell patterning. Taking into account that IDD1 and RGA associate with the same region in CPC promoter, we conclude that CPC is a direct target of the IDD1/RGA complex. In addition, transient expression assays suggested that IDD1 and RGA counteract each other's effects on expression of GA20ox2, GID1b, SCL3, CPC and GL2, providing evidence that IDDs and DELLAs function antagonistically in transcriptional regulation of downstream genes in general. Although both IDDs bear a putative repression motif GLGLGL in their C termini, mutation of this motif did not affect the repressive activity of IDD1 in our transient expression system. On the other hand, fusion of the viral protein 16 (VP16) transcriptional activation domain to IDD1 seems to override the original repressive activity of IDD1. Together, these results uncover a new branch of GA signaling pathway through IDD1 and IDD2, shed light on the interplay of the two IDDs and DELLAs in GA feedback regulation and give insights into the molecular mechanism underlying IDD-mediated GA repression of root hair development.</p> / Dissertation

No description available.

Texte remanié de: Ph.D. th.--School of Oriental and African studies, 1995. / Bibliogr. p. 243-256. Index.

No description available.

'Synthetic Terrain' is the term used for artificially-composed computer-based Digital Terrain Models (DTMs) created by a combination of techniques and heavily influenced by Earth Sciences applications. The synthetic landscape is created to produce 'geographically acceptable', 'realistic' or 'valid' computer-rendered landscapes, maps and 3D images, which are themselves based on synthetic terrain Digital Elevation Models (OEMs). This thesis examines the way in which mainly physical landscapes can be synthesised, and presents the techniques by which terrain data sets can be managed (created, manipulated, displayed and validated), both for academic reasons and to provide a convenient and cost-effective alternative to expensive 'real world' data sets. Indeed, the latter are collected by ground-based or aerial surveying techniques (e.g. photogrammetry), normally at considerable expense, depending on the scale, resolution and type required. The digital information for a real map could take months to collect, process and reproduce, possibly involving demanding Information Technology (IT) resources and sometimes complicated by differing (or contradictory) formats. Such techniques are invalid if the region lies within an 'unfriendly' or inaccessible part of the globe, where (for example), overflying or ground surveys are forbidden. Previous attempts at synthesising terrain have not necessarily aimed at realism. Digital terrain sets have been created by using fractal mathematical models, as 'special effects' for the entertainment industry (e.g. science fiction 'alien' landscapes' for motion pictures and arcade games) or for artistic reasons. There are no known examples of synthesised DTMs being created with such a wide range of requirements and functionality, and with such a regard to validation and realism. This thesis addresses the whole concept of producing' alternative' landscapes in artificial form - nearly 22 years of research aimed at creating' geographically-sensible' synthetic terrain is described with the emphasis on the last 5 years, when this PhD thesis was conceived. These concepts are based on radical, inexpensive and rapid techniques for synthesising terrain, yet value is also placed on the 'validity', realism and 'fitness for purpose' of such models. The philosophy - or the 'thought processes' - necessary to achieve the development of the algorithms leading to synthesised DTMs is one of the primary achievement of the research. This in turn led to the creation of an interactive software package called GEOFORMA, which requires some manual intervention in the form of preliminary terrain classification. The sequence is thus: the user can choose to create terrain or landform assemblages without reference to any real world area. Alternatively, he can select a real world region or a 'typical' terrain type on a 'dial up' basis, which requires a short period of intensive parametric analysis based on research into established terrain classification techniques (such as fractals and other mathematical routines, process-response models etc.) The creates a composite synthesised terrain model of high quality and realism, a factor examined both qualitatively and quantitatively. Although the physical terrain is the primary concern, similar techniques are applied to the human landscape, noting such attributes as the density, type, nature and distribution of settlements, transport systems etc., and although this thread of the research is limited in scope compared with the physical landscape synthesis, some spectacular results are presented. The system also creates place names based on a simple algorithm. Fluvial landscapes, upland regions and coastlines have been selected from the many possible terrain types for 'treatment', and the thesis gives each of these sample landscapes a separate chapter with appropriate illustrations from this original and extensive research. Finally, and inevitably, the work also poses questions in attempting to provide answers, this is perhaps inevitable in a relatively new genre, encompassing so many disciplines, and with relatively sparse literature on the subject.

Diss. phil. Basel (kein Austausch). / Literaturverz.