FEED-FORWARD IN SOFTWARE ENGINEERING WITH PARTICULAR FOCUS ON REQUIREMENTS ENGINEERING AND SOFTWARE ARCHITECTING

This study is intended to determine the characteristics, impact and state of the practice of feed-forward in software engineering; in particular, in the fields of Requirements Engineering (RE) and Software Architecting (SA). Feed-forward is used in many domains such as systems engineering, neural networks, management and psychotherapy. However, in software engineering, especially in RE and SA, the concept of feed-forward is not well researched. For example, what are the characteristics of feed-forward information? What effect does feed-forward information have on architectural artefacts and software project aspects such as cost, quality, time, etc.? What is the current state of practice of feed-forward? A knowledge seeking empirical investigation including an industrial survey and an embedded case study with four projects as four units of analysis were carried out based on these questions. The overall findings ofthis study show that the most common types of information that are fed-forward consistently are requirements and architectural information. This information affects a multitude of aspects of a software project (such as time, cost and quality) and influences several architectural artefacts (such as tactics, patterns and decisions). The results also show that approximately 20% of software professionals have never, or rarely, practiced feed­ forward in their organizations. On the other hand, approximately 66% of software professionals practice feed-forward in their organization in varying levels (“sometimes”, “most of the time”, “always”). 64% of software professionals find feed-forward to be useful for their organization and 4% thought that feed-forward would not be useful, citing reasons such as information overload and lack of motivation. From a researcher’s perspective, determining the properties of feed-forward could provide ground work for doing further research on feed-forward such as: the practice of feed-forward in the other areas of software engineering and the comparison of feedback and feed-forward in software engineerin

THE INFLUENCE OF CULTURE AND SELF-PERCEPTION ON THE MENTAL HEALTH CARE-SEEKING INTENTIONS OF COLLEGE STUDENTS

Mental health issues are common among young adults, especially those attending colleges and universities. There has been a growing concern related to the number of unmet mental health concerns for students and the potential ramifications associated with this unmet need. Studies show that approximately 17% of college students experience a mental health concern, yet only 20% of those with a concern obtain mental health care services. One’s upbringing and background are known to influence decision making and are thus likely to play a role in decisions to seek mental healthcare; however, these norms can vary across cultures. In addition, depending on how one perceives the state of their own mental health, their intentions towards service utilization may be altered. The influence of culture and self-perception on intentions to seek mental health services were examined within this study. Results showed that students were more likely to recommend formal, professional, mental health treatments for their friend rather than themselves, even if symptoms were identical, X2 (1, N = 861) = 96.67, p < 0.001. However, the study did not indicate any significant relationship between background and likelihood to recommend formal treatment options, X2 (1, N = 422) = .549, p = .459, nor attitudes towards seeking professional psychological care, t(832) = -0.592, p = 0.554, d = 0.091. Identification of specific barriers preventing individuals from obtaining formal treatment warrants future research and will aid in development of future direction in how to provide care-services to diverse university populations

Protein-sphingolipid interactions and their role in immunity and disease

Sphingolipids are a diverse class of lipids involved in fundamental cellular processes. In addition to their role in membrane architecture, sphingolipids can act as bioactive molecules, regulate membrane protein function and be presented to the immune system as lipid antigens by CD1 family molecules. The critical importance of sphingolipids for cell function is highlighted by the catastrophic diseases that result from defects in sphingolipid metabolism. Lipid loading onto CD1d is facilitated by the lysosomal lipid transfer protein Saposin B, but the lipid loading mechanism is unknown. I used a range of highly sensitive biochemical assays to probe the interaction between CD1d and SapB. Interestingly, no direct interaction was detectable. Importantly, this suggests that additional proteins may promote their interaction. In addition to their role as antigens, sphingolipids have roles in immunity by regulating the trafficking and function of immune receptors. Krabbe disease, a neurodegenerative disease caused by loss of function of the lysosomal sphingolipid hydrolase GALC, is accompanied by immune defects possibly driven by phagocytic cell dysfunction. I investigated how GALC deficiency alters the phenotype and function of the phagocytic cell line THP-1. This study was compromised by substantial off-target effects caused by genetic manipulation of THP-1 cells. Characterising these off-target changes identified perturbations in sphingolipid metabolism pathways, confirming that these cell lines are not appropriate for further studies. The lysosomal enzyme acid ceramidase (AC) hydrolyses ceramide to sphingosine, thus regulating the levels of pro-apoptotic and pro-survival lipids. This role in apoptosis means that regulation of AC activity is of interest for cancer treatment. Although the structure of AC was recently determined, it is still unclear how it accesses membrane-embedded lipid substrates. I attempted to co-crystallise AC with Saposin A lipoprotein nanodiscs to understand this process. Although this system did not prove suitable for this project, I was able to determine the crystal structure of a new saposin oligomer highlighting even greater diversity of tertiary arrangement of these important lipid transfer proteins. I next asked whether AC processes galactosylceramide to psychosine, the cytotoxic GALC substrate accumulating in Krabbe disease, contributing to Krabbe disease pathology by increasing oligodendrocyte cell death. Surprisingly, I found that GALC knockout oligodendrocytes were not more susceptible to cell death than wild-type oligodendrocytes, calling into question whether psychosine accumulation is the direct cause of oligodendrocyte cell death and demyelination in Krabbe disease. The sphingolipid-interacting adhesion protein PTPRM is lost at the surface of GALC-deficient oligodendrocytes, suggesting that specific sphingolipid-PTPRM interactions cause the mistrafficking of this adhesion protein in Krabbe disease oligodendrocytes, potentially contributing to demyelination. I probed the interaction of PTPRM with sphingolipids through X-ray crystallography studies and fluorescence-based trafficking assays

Does the paucity of elastic fibres contribute to the process of keloidogenesis?

Introduction: Keloids are a prototype of excessive wound healing. Keloid fibroblasts generate traction force, which deforms and realigns the collagen network during migration. Cells move bidirectionally along aligned fibres resulting in nonuniform cell distribution. This and the anisotropic collagen properties displayed in keloids, may be governed by traction force. Excessive traction force (&gt;elastic limit), causes permanent deformations. As recovery from deformational forces is attained mainly by elastic recoil, we hypothesised that in keloids the elastic limit is decreased by reduced numbers of dermal elastic fibres, leading to permanent plastic deformation of dermal tissue by traction force. Objective: To quantitate and compare the elastic fibre content of keloids and non-lesional skin Methods: Sections of keloids and non-lesional skin from 32 patients were stained with elastic Van Gieson. The elastic fibre content was histomorphometrically quantified and the mean (± SEM) percentage area of elastic fibres in lesional and non-lesional skin was compared. Results: Elastic fibres at the border of keloids were increased whereas internally they were minimal or absent. Statistical analysis (Wilcoxon signed ranks test) showed significant differences (p &lt; 0.05) in elastic fibre content between non-lesional dermis and keloids. Conclusions: The lack of elastic fibres in keloids decreases the elastic limit, leading to effects of excessive deformational force. These include compression and stiffening of tissue, increased mitogenesis and cell contractility, modified DNA and protein synthesis and increased collagen biosynthesis. The manifestation of these effects in keloids, supports the hypothesis that decreased elasticity in keloids promotes permanent dermal deformation by traction forces. Keywords: Elastic fibres; wound healing fibroblasts; deformation forces; histomorphometric analysis.Running title: Comparative histomorphometric analysis of elastic fibres in lesional and non-lesional skin of patients with keloid

Computational Modeling for Abnormal Brain Tissue Segmentation, Brain Tumor Tracking, and Grading

This dissertation proposes novel texture feature-based computational models for quantitative analysis of abnormal tissues in two neurological disorders: brain tumor and stroke. Brain tumors are the cells with uncontrolled growth in the brain tissues and one of the major causes of death due to cancer. On the other hand, brain strokes occur due to the sudden interruption of the blood supply which damages the normal brain tissues and frequently causes death or persistent disability. Clinical management of these brain tumors and stroke lesions critically depends on robust quantitative analysis using different imaging modalities including Magnetic Resonance (MR) and Digital Pathology (DP) images. Due to uncontrolled growth and infiltration into the surrounding tissues, the tumor regions appear with a significant texture variation in the static MRI volume and also in the longitudinal imaging study. Consequently, this study developed computational models using novel texture features to segment abnormal brain tissues (tumor, and stroke lesions), tracking the change of tumor volume in longitudinal images, and tumor grading in MR images. Manual delineation and analysis of these abnormal tissues in large scale is tedious, error-prone, and often suffers from inter-observer variability. Therefore, efficient computational models for robust segmentation of different abnormal tissues is required to support the diagnosis and analysis processes. In this study, brain tissues are characterized with novel computational modeling of multi-fractal texture features for multi-class brain tumor tissue segmentation (BTS) and extend the method for ischemic stroke lesions in MRI. The robustness of the proposed segmentation methods is evaluated using a huge amount of private and public domain clinical data that offers competitive performance when compared with that of the state-of-the-art methods. Further, I analyze the dynamic texture behavior of tumor volume in longitudinal imaging and develop post-processing frame-work using three-dimensional (3D) texture features. These post-processing methods are shown to reduce the false positives in the BTS results and improve the overall segmentation result in longitudinal imaging. Furthermore, using this improved segmentation results the change of tumor volume has been quantified in three types such as stable, progress, and shrinkage as observed by the volumetric changes of different tumor tissues in longitudinal images. This study also investigates a novel non-invasive glioma grading, for the first time in literature, that uses structural MRI only. Such non-invasive glioma grading may be useful before an invasive biopsy is recommended. This study further developed an automatic glioma grading scheme using the invasive cell nuclei morphology in DP images for cross-validation with the same patients. In summary, the texture-based computational models proposed in this study are expected to facilitate the clinical management of patients with the brain tumors and strokes by automating large scale imaging data analysis, reducing human error, inter-observer variability, and producing repeatable brain tumor quantitation and grading

Local-global analysis of crack growth in continuously reinforced ceramic matrix composites

The development is described of a mathematical model for predicting the strength and micromechanical failure characteristics of continuously reinforced ceramic matrix composites. The local-globe analysis models the vicinity of a propagating crack tip as a local heterogeneous region (LHR) consisting of spring like representation of the matrix, fibers and interfaces. This region is embedded in an anisotropic continuum (representing the bulk composite) which is modeled by conventional finite elements. Parametric studies are conducted to investigate the effects of LHR size, component properties, interface conditions, etc. on the strength and sequence of the failure processes in the unidirectional composite system. The results are compared with those predicted by the models developed by Marshall et al. (1985) and by Budiansky et al. (1986)