Eigenfunction expansion of the time and space-dependent neutron survival probability equation

Owing to their inherent complexity, stochastic neutron transport problems are often examined by either using highly simplified models to make solutions more accessible, or at the cost of significant computational effort for problems demanding higher accuracy than such simplified models afford. In this work, solutions to stochastic transport equations of varying complexity are developed to examine a particular quantity of interest, the neutron survival probability. Using these solutions, the behavior of the survival probability is characterized throughout a wide range of parameters to better inform expectations as the complexity of the problem is increased. First, the survival probability is modeled in an infinite medium. This provides insight into the relationship between the survival probability and the passage of survival time, the effective multiplication factor of the system, and the number of factorial moments of fission multiplicity preserved in the equation. A steady-state diffusion equation is then solved semi-analytically in a one-dimensional slab, expanding understanding of the behavior of the survival probability and providing a benchmark for other space-dependent solutions. Additional steady-state solutions are produced by recognizing that the survival probability is well-approximated by the first eigenfunction of the linear portion of the equation. Not only is strong agreement observed with the semi-analytical solution, extension to other geometries is made accessible and the impact that varying geometry has on the survival probability is demonstrated. Finally, solutions to the time and space-dependent survival probability diffusion equation are computed using an eigenfunction expansion technique. By comparison to the available semi-analytical steady-state solutions, as well as the known ``initial condition, the eigenfunction expansion technique demonstrates the capacity to produce solutions of arbitrary accuracy throughout the available parameter space. Extension to other geometries and multi-dimensional problems is performed, showing the broad capabilities of the technique as well as exploring facets of its performance. Additionally, a linear stability analysis of the equilibrium solution produced by the eigenfunction expansion technique is performed, rigorously demonstrating the stability of the associated solutions

The search for an ideal mesenchymal stromal cell donor in the horse : this dissertation is presented for partial fulfillment of the degree of Doctor of Philosophy in Veterinary Science, Massey University, Palmerston North, New Zealand, School of Veterinary Science

The search for an immune privileged allogeneic mesenchymal stromal cell (MSC) line has been an interest for many biomedical researchers. This holds true for the field of equine medicine where MSCs are frequently used in research and clinical cases for the treatment of musculoskeletal disease. An ideal allogeneic MSC suppresses the immune system of the recipient leading to decreased inflammation in the face of disease. The ideal MSC also expresses the markers of a multipotent cell, retains a high level of viability and is able to perform anabolic activities to enhance repair. Our research sought to more clearly define the expression of MSC markers harvested from different equine MSC donors. Bone marrow-derived MSCs from Thoroughbreds, Standardbreds, and a subset of universal blood donor-type Standardbreds were compared. Standardbred MSCs showed significantly less MHC class II expression at early passages as compared to Thoroughbreds. When universal blood donor Standardbreds were compared to non-blood donor Standardbreds, the only significant variation was that CD90 was expressed more highly on universal blood donor MSCs as compared to non-blood donor Standardbred MSCs. The conclusion from stage one of our research was that universal blood donor-type Standardbred horses appeared less likely to cause an MHC II driven immune reaction and had the highest levels of bone marrow-derived MSC markers expressed at passage 2-4. We then compared the MSC donor cells in an in vitro trial exploring several arms of the immune system to understand the effects of the MSCs without prior activation of the immune cells, as has been done previously. Overwhelmingly, we found that MSCs of allogeneic origin cause very little to no activation of the immune system as compared to autologous MSCs. B cell and activated T lymphocyte populations were similar between the autologous and allogeneic MSCs. Those allogeneic MSCs that expressed little MHC II prior to interaction with the immune cells (MHC II-low MSCs) had reduced activation of recipient lymphocytes and neutrophils as compared to those MSCs expressing high levels of MHC II prior to interaction with immune cells (MHC II-high MSCs). MHC II-low MSCs, both of universal blood donor and non-blood donor origin, had higher expression of the genes we studied when placed in an allogeneic environment. These include both anabolic molecules known to assist in healing and some catabolic molecules. This knowledge combined with published information that ‘activated’ MSCs can be more beneficial to healing than unactivated MSCs, support the use of the more metabolically active MHC II-low MSCs as compared to MHC II-high MSCs. Based upon a wide array of testing, allogeneic MHC II-low MSCs created a low level of immune activation and an increased level of gene anabolic gene expression as compared to autologous MSCs. In conclusion passage 2-4 MHC II-low MSCs are preferred for use in allogeneic therapy

PARADISE: A Framework for Evaluating Spoken Dialogue Agents

This paper presents PARADISE (PARAdigm for DIalogue System Evaluation), a general framework for evaluating spoken dialogue agents. The framework decouples task requirements from an agent's dialogue behaviors, supports comparisons among dialogue strategies, enables the calculation of performance over subdialogues and whole dialogues, specifies the relative contribution of various factors to performance, and makes it possible to compare agents performing different tasks by normalizing for task complexity.Comment: 10 pages, uses aclap, psfig, lingmacros, time

Other‐Sacrificing Options

I argue that you can be permitted to discount the interests of your adversaries even though doing so would be impartially suboptimal. This means that, in addition to the kinds of moral options that the literature traditionally recognises, there exist what I call other-sacrificing options. I explore the idea that you cannot discount the interests of your adversaries as much as you can favour the interests of your intimates; if this is correct, then there is an asymmetry between negative partiality toward your adversaries and positive partiality toward your intimates

Mechano-sensing and cell migration: A 3D model approach

Cell migration is essential for tissue development in different physiological and pathological conditions. It is a complex process orchestrated by chemistry, biological factors, microstructure and surrounding mechanical properties. Focusing on the mechanical interactions, cells do not only exert forces on the matrix that surrounds them, but they also sense and react to mechanical cues in a process called mechano-sensing. Here, we hypothesize the involvement of mechano-sensing in the regulation of directional cell migration through a three-dimensional (3D) matrix. For this purpose, we develop a 3D numerical model of individual cell migration, which incorporates the mechano-sensing process of the cell as the main mechanism regulating its movement. Consistent with this hypothesis, we found that factors, such as substrate stiffness, boundary conditions and external forces, regulate specific and distinct cell movements

Oxygen levels in thermoplastic microfluidic devices during cell culture

We developed a computational model to predict oxygen levels in microfluidic plastic devices during cell culture. This model is based on experimental evaluation of oxygen levels. Conditions are determined that provide adequate oxygen supply to two cell types, hepatocytes and endothelial cells, either by diffusion through the plastic device, or by supplying a low flow rate of medium

Digital Deblurring of CMB Maps II: Asymmetric Point Spread Function

In this second paper in a series dedicated to developing efficient numerical techniques for the deblurring Cosmic Microwave Background (CMB) maps, we consider the case of asymmetric point spread functions (PSF). Although conceptually this problem is not different from the symmetric case, there are important differences from the computational point of view because it is no longer possible to use some of the efficient numerical techniques that work with symmetric PSFs. We present procedures that permit the use of efficient techniques even when this condition is not met. In particular, two methods are considered: a procedure based on a Kronecker approximation technique that can be implemented with the numerical methods used with symmetric PSFs but that has the limitation of requiring only mildly asymmetric PSFs. The second is a variant of the classic Tikhonov technique that works even with very asymmetric PSFs but that requires discarding the edges of the maps. We provide details for efficient implementations of the algorithms. Their performance is tested on simulated CMB maps.Comment: 9 pages, 13 Figure