A general finite difference discretization of the time-dependent radiation transport equation is developed around the framework of an existing steady-state three dimensional radiation transport solver based on the slice-balance approach. Three related algorithms are outlined within the general finite difference scheme: an explicit, an implicit, and a semi-implicit approach. The three algorithms are analyzed with respect to the discretizations of each element of the phase space in the transport solver. The explicit method, despite its small computational cost per time step, is found to be unsuitable for many purposes due to its inability to accurately handle rapidly varying solutions. The semi-implicit method is shown to produce results nearly as reliable as the fully implicit solver, while requiring significantly less computational effort.

We present a slice-based method that combined with fluid-solid interaction to render the oceans interact with the objects of the simulation. First, according to the key slices selection one can determine the initial slices simulation for reducing the computation on the number of grid and expressing the solid appearance. Second, we used 3D vector Navier-Stokes equations and combined with 3D fluid-solid coupling to comply with the laws of physics for 2D slice simulation. Third, using a volume of fluid method one can reconstruct the 2D ocean surface and further apply interpolation to extended 2D surfaces to 3D ocean surface. Finally, using the Doo-Sabin subdivision surfaces method is to be smoother for the 3D surface. From the viewpoint of ocean simulation, we can not only solve the fluid-solid coupling problem of objects floating on the sea but also achieve better result in efficiency compared with traditional ocean simulation. From the viewpoint of fluid-solid coupling, the proposed method can greatly reduce the computation in number of grid and be applied to embedded systems, games or films effectively.

Slices are digraphs that can be composed together to form larger digraphs.In this thesis we introduce the foundations of a theory whose aim is to provide ways of defining and manipulating infinite families of combinatorial objects such as graphs, partial orders, logical equations etc. We give special attentionto objects that can be represented as sequences of slices. We have successfully applied our theory to obtain novel results in three fields: concurrency theory,combinatorics and logic. Some notable results are: Concurrency Theory: We prove that inclusion and emptiness of intersection of the causalbehavior of bounded Petri nets are decidable. These problems had been open for almost two decades. We introduce an algorithm to transitively reduce infinite familiesof DAGs. This algorithm allows us to operate with partial order languages defined via distinct formalisms, such as, Mazurkiewicztrace languages and message sequence chart languages. Combinatorics: For each constant z ∈ N, we define the notion of z-topological or-der for digraphs, and use it as a point of connection between the monadic second order logic of graphs and directed width measures, such as directed path-width and cycle-rank. Through this connection we establish the polynomial time solvability of a large numberof natural counting problems on digraphs admitting z-topological orderings. Logic: We introduce an ordered version of equational logic. We show thatthe validity problem for this logic is fixed parameter tractable withrespect to the depth of the proof DAG, and solvable in polynomial time with respect to several notions of width of the equations being proved. In this way we establish the polynomial time provability of equations that can be out of reach of techniques based on completion and heuristic search. / <p>QC 20131120</p>

Exposure to ethanol (ETOH) during fetal development results in a range of cognitive/behavioral deficits. There are differences in sensitivity to the effects of ETOH that could be explained by other factors, such as hypoxia. Similar mechanisms of damage underlie both ETOH, more specifically ETOH withdrawal, and hypoxia. Based on this overlap, it was hypothesized that sub threshold levels of these insults may interact to produce increased damage in sensitive brain regions. This study used a rodent organotypic hippocampal slice culture model to investigate the interaction of hypoxia and ETOH withdrawal and to determine possible developmental differences in the sensitivity to these insults. The combination of ETOH and hypoxia produced greater damage in the CA1 and CA3 hippocampal regions, as measured by propidium iodide uptake. Differences in outcome were noted between on postnatal (PND) 2 and PND 8 tissue. ETOH alone caused damage as measured by the neuronal marker NeuN, suggesting the ETOH/hypoxia interaction involves different cell types and that caution should be taken when determining appropriate levels of exposure. This data could explain why some offspring appear more sensitive to ETOH and/or hypoxic challenges during early life.

The concept of game development has traditionally not implemented the skills of professional writers to develop the scripts for a computer game. However, due to the growth in complexity and size of the computer game development process, as well as the growing teams of people involved in the development of computer games, the need to employ skilled writers has emerged in modern computer game development. It has, however, become clear that the role of the writer within the collaborative game development process is still ill-defined. And therefore, the writer who wishes to start writing for the games industry, is faced with a great deal of obstacles. It was therefore deemed necessary to develop a script development model for the creation of computer games that can assist the writer of a computer game by means of thorough guidance. The aim of this research project is therefore to develop such a model. The first step towards the establishment of a script development model, would be to determine the position of the writer in the collaborative game production communication process. In order to establish this, a communication model was developed for the communication process of the computer game development process, based on Roman Jakobson's communication model. After the position of the writer in the communication process was established, a game development model was developed to determine the position of the writer within the entire game development process. This was done so that the functions and responsibilities of the writer - within a greater collaborative development process - could be determined. This model was developed based on existing software development models, as well as two different models from the games industry that focus on different aspects within the game development process. With the position, functions and responsibilities of the writer determined, it was possible to postulate a script development model for the creation of computer games. This model was developed with an emphasis on the game context, creative strategies and analytical frameworks available to the writer. Furthermore guidelines were provided on the actual scripting of the computer game script, based on elements from drama theory. To test the script development model, a non-functional prototype (thin-slice) computer game script was developed based on the Fritz Deelman-series (Leon Rousseau). The script development model was used as guideline to establish whether the script development model could in future be used to develop a full-scale, implementable computer game script. / Thesis (M.A. (Afrikaans and Dutch))--North-West University, Potchefstroom Campus, 2008.

The concept of game development has traditionally not implemented the skills of professional writers to develop the scripts for a computer game. However, due to the growth in complexity and size of the computer game development process, as well as the growing teams of people involved in the development of computer games, the need to employ skilled writers has emerged in modern computer game development. It has, however, become clear that the role of the writer within the collaborative game development process is still ill-defined. And therefore, the writer who wishes to start writing for the games industry, is faced with a great deal of obstacles. It was therefore deemed necessary to develop a script development model for the creation of computer games that can assist the writer of a computer game by means of thorough guidance. The aim of this research project is therefore to develop such a model. The first step towards the establishment of a script development model, would be to determine the position of the writer in the collaborative game production communication process. In order to establish this, a communication model was developed for the communication process of the computer game development process, based on Roman Jakobson's communication model. After the position of the writer in the communication process was established, a game development model was developed to determine the position of the writer within the entire game development process. This was done so that the functions and responsibilities of the writer - within a greater collaborative development process - could be determined. This model was developed based on existing software development models, as well as two different models from the games industry that focus on different aspects within the game development process. With the position, functions and responsibilities of the writer determined, it was possible to postulate a script development model for the creation of computer games. This model was developed with an emphasis on the game context, creative strategies and analytical frameworks available to the writer. Furthermore guidelines were provided on the actual scripting of the computer game script, based on elements from drama theory. To test the script development model, a non-functional prototype (thin-slice) computer game script was developed based on the Fritz Deelman-series (Leon Rousseau). The script development model was used as guideline to establish whether the script development model could in future be used to develop a full-scale, implementable computer game script. / Thesis (M.A. (Afrikaans and Dutch))--North-West University, Potchefstroom Campus, 2008.

Background: Human head and neck squamous cell carcinoma (HNSCC) fundamentally vary in their susceptibility to different cytotoxic drugs and treatment modalities. There is at present no clinically accepted test system to predict the most effective therapy for an individual patient. Methods: Therefore, we established tumor-derived slice cultures which can be kept in vitro for at least six days. Upon treatment with cisplatin, docetaxel and cetuximab, slices were fixed and paraffin sections were cut for histopathological analysis. Results: Apoptotic fragmentation, activation of caspase 3, and cell loss were observed in treated tumor slices. Counts of nuclei per field in untreated compared to treated slices deriving from the same tumor allowed estimation of the anti-neoplastic activity of individual drugs on an individual tumor. Conclusion: HNSCC-derived slice cultures survive well in vitro and may serve to improve personalized therapies, but also to detect mechanisms of tumor resistance by harvesting surviving tumor cells after treatment.

In this thesis, we discuss some topics in random matrix theory which have applications to probability, statistics and quantum information theory. In Chapter 2, by relying on the spectral properties of an associated adjacency matrix, we find the distribution of the maximum of a Dyck path and show that it has the same distribution function as the unsigned Brownian excursion which was first derived in 1976 by Kennedy. We obtain a large and moderate deviation principle for the law of the maximum of a random Dyck path. Our result extends the results of Chung, Kennedy and Khorunzhiy and Marckert. In Chapter 3, we discuss a method of sampling called the Gibbs-slice sampler. This method is based on Neal's slice sampling combined with Gibbs sampling. In Chapter 4, we discuss several examples which have applications in physics and quantum information theory.

abstract: The objective of this work is to design a low-profile compact Terahertz (THz) imaging system that can be installed in portable devices, unmanned aerial vehicles (UAVs), or CubeSats. Taking advantage of the rotational motion of these platforms, one can use linear antennas, such as leaky-wave antennas or linear phased arrays, to achieve fast image acquisition using simple RF front-end topologies. The proposed system relies on a novel image reconstructing technique that uses the principles of computerized tomography (Fourier-slice theorem). It can be implemented using a rotating antenna that produces a highly astigmatic fan-beam. In this work, the imaging system is composed of a linear phased antenna array with a highly directive beam pattern in the E-plane allowing for high spatial resolution imaging. However, the pattern is almost omnidirectional in the H-plane and extends beyond the required field-of-view (FOV). This is a major drawback as the scattered signals from any interferer outside the FOV will still be received by the imaging aperture and cause distortion in the reconstructed image. Also, fan beams exhibit significant distortion (curvature) when tilted at large angles, thus introducing errors in the final image due to its failure to achieve the assumed reconstructing algorithm. Therefore, a new design is proposed to alleviate these disadvantages. A 14×64 elements non-uniform array with an optimal flat-top pattern is designed with an iterative process using linear perturbation of a close starting pattern until the desired pattern is acquired. The principal advantage of this design is that it restricts the radiated/received power into the required FOV. As a result, a significant enhancement in the quality of images is achieved especially in the mitigation of the effect of any interferer outside the FOV. In this report, these two designs are presented and compared in terms of their imaging efficiency along with a series of numerical results verifying the proof of concept. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

Perfect slice sampling is a method to turn Markov Chain Monte Carlo (MCMC) samplers into exact generators for independent random variates. We show that the simplest version of the perfect slice sampler suggested in the literature does not always sample from the target distribution. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics