Balanced flux formulations for multidimensional Evans function computations for viscous shocks

The Evans function is a powerful tool for the stability analysis of viscous shock profiles; zeros of this function carry stability information. In the one-dimensional case, it is typical to compute the Evans function using Goodman's integrated coordinates [G1]; this device facilitates the search for zeros of the Evans function by winding number arguments. Although integrated coordinates are not available in the multidimensional case, we show here that there is a choice of coordinates which gives similar advantages

Intelligent Products in Supply/Demand Networks: Steps to Developing a Simulation Environment for Concept Evaluation

Supply/Demand networks are undergoing rapid changes with the increasing use of dynamic rather than static information. This paper discusses the idea of intelligent products as both producers and consumers of dynamic information, before describing research in progress to develop a suitable simulation environment for experimenting with the intelligent product concept. The research will briefly consider the potential of a new Microsoft parallel programming environment (Axum) as a development tool

CD155 on HIV-infected cells is not modulated by HIV-1 Vpu and Nef but synergizes with NKG2D ligands to trigger NK cell lysis of autologous primary HIV-infected cells

Activation of primary CD4(+) T cells induces the CD155, but not the CD112 ligands for the natural killer (NK) cell activation receptor (aNKR) CD226 [DNAX accessory molecule-1 (DNAM-1)]. We hypothesize that HIV productively infects activated CD4(+) T cells and makes itself vulnerable to NK cell-mediated lysis when CD155 on infected T cells engages DNAM-1. The primary objective of this study is to determine whether CD155 alone or together with NKG2D ligands triggers autologous NK cell lysis of HIV-infected T cells and whether HIV modulates CD155. To determine whether HIV modulates this activation ligand, we infected “activated” CD4(+) T cells with HIV in the absence or presence of Nef and/or Vpu and determined by flow cytometry whether they modulated CD155. To determine if CD155 alone, or together with NKG2D ligands, triggered NK cell lysis of autologous HIV-infected T cells, we treated purified NK cells with DNAM-1 and/or NKG2D blocking antibodies before the addition of purified autologous HIV-infected cells in cytolytic assays. Finally, we determined whether DNAM-1 works together with NKG2D as an NK cell coactivation receptor (caNKR) or whether they work independently as aNKRs to induce an NK cell lytic response. We demonstrate that HIV and specifically Nef and/or Vpu do not modulate CD155 on infected primary T cells; and both CD155 and NKG2D ligands synergize as aNKRs to trigger NK cell lysis of the infected cell

Estimation of Cerebral Physiology and Hemodynamics via Near-Infrared Spectroscopy

Near-infrared spectroscopy (NIRS) is a non-invasive optical imaging technique that has rapidly been gaining popularity for study of the brain. Near-infrared spectroscopy measures absorption of light, primarily due to hemoglobin, through an array of light sources and detectors that are coupled to the scalp. Measurements can generally be divided into measurements of baseline physiology (related to total absorption) and measurements of hemodynamic time-series data (related to relative absorption changes). Because light intensity drops off rapidly with depth, NIRS measurements are highly sensitive to extracerebral tissues. Attempts to recover baseline physiology measurements of the brain can be confounded by high sensitivity to the scalp and skull. Time-series measurements contain high contributions of systemic physiology signals, including cardiac, respiratory, and blood pressure waves. Furthermore, measurements over time inevitably introduce artifacts due to subject motion. The aim of this thesis was to develop improved analysis methods in the context of these NIRS specific confounding factors. The thesis consists of four articles that address specific issues in NIRS data analysis: (i) assessment of common data analysis procedures used to estimate oxygen saturation and hemoglobin content that assume a semi-infinite, homogeneous medium, (ii) testing the feasibility of improving oxygen saturation and hemoglobin measurements using multi-layered models, (iii) development of methods to estimate the general linear model for functional brain imaging that are robust to systemic physiology signals and motion artifacts, and (iv) the extension of (iii) to an adaptive method that is suitable for real-time analysis. Overall, this thesis helps to validate and advance analysis methods for NIRS