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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Creating deformations and tunnels in a surface using layered geometry with adaptive filtering

Brooks, Jacob Kirk 01 November 2005 (has links)
With this thesis, I present a method for creating footprints and tunnels in a surface through the use of layered geometry. Rather than using a single geometric surface, deformations are created through the interaction of a polygonal object with multiple layered planes. Contrary to common methods such as solely using displacement maps or techniques used in fluid dynamics, none of the layered geometry moves. With adaptive filtering and layered geometry, one can create complex deformations resulting from sliding, digging, and surfacing. Its volumetric nature allows interaction to create overlapping shapes, tunnels, and holes in a surface, while alleviating the ultimate problem of broken geometry.
2

Bloody footprints : learning to be with woman

Browne, Jennifer, n/a January 2000 (has links)
n/a
3

The Footprint Sorting Problem

Fried, Claudia, Hordijk, Wim, Prohaska, Sonja J., Stadler, Claus R., Stadler, Peter F. 07 January 2019 (has links)
Phylogenetic footprints are short pieces of noncoding DNA sequence in the vicinity of a gene that are conserved between evolutionary distant species. A seemingly simple problem is to sort footprints in their order along the genomes. It is complicated by the fact that not all footprints are collinear:  they may cross each other. The problem thus becomes the identification of the crossing footprints, the sorting of the remaining collinear cliques, and finally the insertion of the noncollinear ones at “reasonable” positions. We show that solving the footprint sorting problem requires the solution of the “Minimum Weight Vertex Feedback Set Problem”, which is known to be NP-complete and APX-hard. Nevertheless good approximations can be obtained for data sets of interest. The remaining steps of the sorting process are straightforward:  computation of the transitive closure of an acyclic graph, linear extension of the resulting partial order, and finally sorting w.r.t. the linear extension. Alternatively, the footprint sorting problem can be rephrased as a combinatorial optimization problem for which approximate solutions can be obtained by means of general purpose heuristics. Footprint sortings obtained with different methods can be compared using a version of multiple sequence alignment that allows the identification of unambiguously ordered sublists. As an application we show that the rat has a slighly increased insertion/deletion rate in comparison to the mouse genome.
4

Independent Hox‐cluster duplications in lampreys

Fried, Claudia, Prohaska, Sonja J., Stadler, Peter F. 07 January 2019 (has links)
The analysis of the publicly available Hox gene sequences from the sea lamprey Petromyzon marinus provides evidence that the Hox clusters in lampreys and other vertebrate species arose from independent duplications. In particular, our analysis supports the hypothesis that the last common ancestor of agnathans and gnathostomes had only a single Hox cluster which was subsequently duplicated independently in the two lineages.
5

Taphonomy of modern and ancient vertebrate traces in the marginal sediments of saline, alkaline and freshwater lakes, Baringo-Bogoria basin, Kenya Rift Valley

Scott, Jennifer Jane 08 September 2005
Actualistic, sedimentological, and experimental approaches to the study of vertebrate trace taphonomy in the Kenya Rift Valley have permitted the characterization and even quantification of factors that influence trace morphology and preservation potential in semi-arid lake margins. Several important taphonomic factors were identified from the modern lake-marginal sediments of saline, alkaline Lake Bogoria and freshwater Lake Baringo in the Baringo-Bogoria basin (1º N and 36º E). The investigation of these factors, considering vertebrate ecology and sedimentology of the deposits, together with the study of early and later diagenetic processes that cement substrates, provided a framework for the paleoecological interpretation of three Pleistocene fossil footprint localities, also in the Baringo-Bogoria basin. The most important taphonomic factors appear to be related to the semi-arid climate (e.g., high evaporation:precipitation ratio), frequent lake level changes, the closed nature of the lake basins, bedrock geology (mainly volcaniclastic) within the catchment, and the chemical composition of lake and pore waters. Notable factors that cause the alteration, destruction, and stabilization of traces include efflorescent salt crystallization, which may temporarily cement substrates or destroy traces during crystal growth in the capillary fringe; substrate wetting and drying, which can induce soil-crusting and the shrinking and swelling of smectitic clays; and the presence of benthic microbial mats and biofilms, which may temporarily stabilize substrates or contribute to their early cementation by mediating carbonate precipitation. Experiments to quantitatively and statistically test the effects of salt efflorescence, the rate and temperature of substrate drying (e.g., sun-baking), and swelling and non-swelling clays supported field observations. Preservational processes interpreted from Pleistocene footprint-bearing sediments include the early cementation of substrates by carbonates (e.g., calcite), and during prolonged, stable dry phases, the precipitation of zeolitic cements and Mn- and Fe-oxide minerals. ****PLEASE NOTE: This thesis is formatted to be printed double-sided.
6

Taphonomy of modern and ancient vertebrate traces in the marginal sediments of saline, alkaline and freshwater lakes, Baringo-Bogoria basin, Kenya Rift Valley

Scott, Jennifer Jane 08 September 2005 (has links)
Actualistic, sedimentological, and experimental approaches to the study of vertebrate trace taphonomy in the Kenya Rift Valley have permitted the characterization and even quantification of factors that influence trace morphology and preservation potential in semi-arid lake margins. Several important taphonomic factors were identified from the modern lake-marginal sediments of saline, alkaline Lake Bogoria and freshwater Lake Baringo in the Baringo-Bogoria basin (1º N and 36º E). The investigation of these factors, considering vertebrate ecology and sedimentology of the deposits, together with the study of early and later diagenetic processes that cement substrates, provided a framework for the paleoecological interpretation of three Pleistocene fossil footprint localities, also in the Baringo-Bogoria basin. The most important taphonomic factors appear to be related to the semi-arid climate (e.g., high evaporation:precipitation ratio), frequent lake level changes, the closed nature of the lake basins, bedrock geology (mainly volcaniclastic) within the catchment, and the chemical composition of lake and pore waters. Notable factors that cause the alteration, destruction, and stabilization of traces include efflorescent salt crystallization, which may temporarily cement substrates or destroy traces during crystal growth in the capillary fringe; substrate wetting and drying, which can induce soil-crusting and the shrinking and swelling of smectitic clays; and the presence of benthic microbial mats and biofilms, which may temporarily stabilize substrates or contribute to their early cementation by mediating carbonate precipitation. Experiments to quantitatively and statistically test the effects of salt efflorescence, the rate and temperature of substrate drying (e.g., sun-baking), and swelling and non-swelling clays supported field observations. Preservational processes interpreted from Pleistocene footprint-bearing sediments include the early cementation of substrates by carbonates (e.g., calcite), and during prolonged, stable dry phases, the precipitation of zeolitic cements and Mn- and Fe-oxide minerals. ****PLEASE NOTE: This thesis is formatted to be printed double-sided.
7

Understanding and Improving Navigation Within Electronic Documents

Alexander, Jason January 2009 (has links)
Electronic documents form an integral part of the modern computer age---virtually all personal computers have the ability to create, store and display their content. A connection to the Internet provides users with an almost endless source of documents, be they web-pages, word-processor files or emails. However, the entire contents of an electronic document are often too large to be usefully presented on a user’s screen, at a single point in time. This issue is usually overcome by placing the content inside a scrolling environment. The view onto the document is then modified by directly adjusting a scrollbar or by employing tools such as the mousewheel or paging keys. Applications may also provide methods for adjusting the document’s zoom and page layout. The scrollbar has seen widespread adoption, becoming the default tool used to visualise large information spaces. Despite its extensive deployment, researchers have little knowledge on how this and related navigation tools are used in an everyday work environment. A characterisation of users’ actions would allow designers to identify common behaviours and areas of inefficiency as they strive to improve navigation techniques. To fill this knowledge gap, this thesis aims to understand and improve navigation within desktop-based electronic documents. This goal is achieved using a five step process. First, the literature is used to explore document navigation tasks and the tools currently available to support electronic document navigation. Second, a software tool called AppMonitor, that logs users’ navigation actions, was developed. Third, AppMonitor was deployed in a longitudinal study to characterise document navigation actions in Microsoft Word and Adobe Reader. Forth, to compliment this study, two task-centric observations of electronic document navigation were performed, to probe the reasons for navigation tool selection. Finally, the Footprints Scrollbar was developed to improve one common aspect of navigation—within-document revisitation. To begin, two areas of current knowledge in this domain are overviewed: paper and electronic document navigation and electronic document navigation tools. The literature review produced five categories of document navigation tasks: ‘overviewing and browsing’, ‘reading’, ‘annotating and writing’, ‘searching’ and ‘revisitation’. In a similar fashion, electronic document navigation tools were reviewed and divided into eight categories: core navigation tools (those commonly found in today’s navigation systems), input devices, scrollbar augmentations, content-aware navigation aids, visualisations that provide multiple document views, indirect manipulation techniques, zooming tools and revisitation tools. The literature lacked evidence of an understanding of how these current document navigation tools are used. To aid the gathering of empirical data on tool use, the AppMonitor tool was developed. It records user actions in unmodified Windows applications—specifically for this research, Microsoft Word and Adobe Reader. It logs low-level interactions such as “left mouse button pressed” and “Ctrl-f pressed” as well as high level ‘logical’ actions such as menu selections and scrollbar manipulations. It requires no user input to perform these tasks, allowing study participants to continue with their everyday work. To collect data to form a characterisation of document navigation actions, 14 participants installed AppMonitor on their computer for 120 days. This study found that users primarily employ the mousewheel, scrollbar thumb and paging keys for navigation. Further, many advanced navigation tools that are lauded for their efficiency, including bookmarks and search tools, are rarely used. The longitudinal study provided valuable insights into the use of navigation tools. To understand the reasons behind this tool use, two task-centric observations of electronic document navigation were conducted. The first asked participants to perform a series of specific navigation tasks while AppMonitor logged their actions. The second was performed as a series of interactive sessions, where users performed a particular task and were then probed on their tool choice. These two studies found that many users are not aware of the advanced navigation tools that could significantly improve their navigation efficiency. Finally, the characterisations highlighted within-document revisitation as a commonly performed task, with current tools that support this action rarely used. To address this problem, the analysis, design and evaluation of a Footprints Scrollbar is presented. It places marks inside the scrollbar trough and provides shortcuts to aid users return to previously visited locations. The Footprints Scrollbar was significantly faster and subjectively preferred over a standard scrollbar for revisitation tasks. To summarise, this thesis contributes a literature review of document navigation and electronic document navigation tools; the design and implementation of AppMonitor—a tool to monitor user actions in unmodified Windows applications; a longitudinal study describing the navigation actions users perform; two taskcentric studies examining why actions are performed; and the Footprints Scrollbar, a tool to aid within-document revisitation tasks.
8

On the Determination of Building Footprints from LIDAR Data

George, Henry C. 15 December 2007 (has links)
A new approach to improve the determination of building boundaries through automatic processing of light detection and ranging (LIDAR) data is presented. The LIDAR data is processed and interpolated into a grayscale image of intensity values corresponding to height measurements. Ground measurements are separated from non-ground measurements by using a progressive morphological filter. With these measurements now distinct, further separation of non-ground measurements into building and non-building measurements is performed by growing regions with similar characteristics. These building areas are then refined, resulting in a ground plan representation of building boundaries, known as building footprints. Several algorithms are then implemented to clean these footprints. A new method is developed to analyze actual known satellite imagery in order to confirm identified building footprints.
9

Identification of change in a dynamic dot pattern and its use in the maintenance of footprints

Dupenois, Maximillian Philip January 2012 (has links)
Examples of spatio-temporal data that can be represented as sets of points (called dot patterns) are pervasive in many applications, for example when tracking herds of migrating animals, ships in busy shipping channels and crowds of people in everyday life. The use of this type of data extends beyond the standard remit of Geographic Information Science (GISc), as classification and optimisation problems can often be visualised in the same manner. A common task within these fields is the assignment of a region (called a footprint) that is representative of the underlying pattern. The ways in which this footprint can be generated has been the subject of much research with many algorithms having been produced. Much of this research has focused on the dot patterns and footprints as static entities, however for many of the applications the data is prone to change. This thesis proposes that the footprint need not necessarily be updated each time the dot pattern changes; that the footprint can remain an appropriate representation of the pattern if the amount of change is slight. To ascertain the appropriate times at which to update the footprint, and when to leave it as it is, this thesis introduces the concept of change identifiers as simple measures of change between two dot patterns. Underlying the change identifiers is an in-depth examination of the data inherent in the dot pattern and the creation of descriptors that represent this data. The experimentation performed by this thesis shows that change identifiers are able to distinguish between different types of change across dot patterns from different sources. In doing so the change identifiers reduce the number of updates of the footprint while maintaining a measurably good representation of the dot pattern.
10

Global Sustainability Accounting - Developing EXIOBASE for Multi-Regional Footprint Analysis

Wood, Richard, Stadler, Konstantin, Bulavskaya, Tatyana, Lutter, Franz Stephan, Giljum, Stefan, de Koning, Arjan, Kuenen, Jeroen, Schütz, Helmut, Acosta-Fernández, José, Usubiaga, Arkaitz, Simas, Moana, Ivanova, Olga, Weinzettel, Jan, Schmidt, Jannick, Merciai, Stefano, Tukker, Arnold 26 December 2014 (has links) (PDF)
Measuring progress towards sustainable development requires appropriate frameworks and databases. The System of Environmental-Economic Accounts (SEEA) is undergoing continuous refinement with these objectives in mind. In SEEA, there is a need for databases to encompass the global dimension of societal metabolism. In this paper, we focus on the latest effort to construct a global multi-regional input-output database (EXIOBASE) with a focus on environmentally relevant activities. The database and its broader analytical framework allows for the as yet most detailed insight into the production-related impacts and "footprints" of our consumption. We explore the methods used to arrive at the database, and some key relationships extracted from the database.

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