Investigating immunological responses of WC1+ gamma delta T cells in cattle naturally infected with mycobacterium avium subspecies paratuberculosis (MAP)

In these studies, we used non-infected cattle and cattle naturally infected with MAP that were either in the subclinical or clinical stage of infection to test the hypothesis that infection status influences WC1+ γδ T cells frequency, proliferation, and cytokine production. We found no significant differences between subclinical and clinical cattle with regard to WC1+ γδ T cells frequency in peripheral blood or in the ileum, a primary site for MAP infection. In PBMCs taken from MAP-infected cattle, WC1+ γδ T cells responded diffrentially to stimulation with PPD-J. In the clinical group, WC1+ γδ T cells failed to proliferate and the WC1.1 subset did not produce IFN-γ or IL-10 suggesting unresponsiveness. We evaluated the cytokine profile (mRNA) of the WC1+ γδ T cell subset in the ileum. Our data indicate a significant increase in the numbers of WC1+ γδ T cells expressing IL-10 in ileal tissues obtained from clinical cattle compared to subclinical and non-infected cattle. Expression of IFN-γ, TNF-α, IL-17 and TGF-β by the WC1+ γδ T cell subset in the ileum was comparable among the examined groups. We used subclinical infected cattle to evaluate the impact of WC1+ γδ T cell depletion on cytokine production by PBMCs stimulated ex vivo with PPD-J. Independent of antigen (PPD), depletion of WC1+ γδ T cells resulted in a significant decrease in IL-4 secretion and a significant increase in IL-10 secretion suggesting a modulatory role for the WC1+ subset in this system. The present dissertation supports our hypothesis that MAP infection status influences immunological responses of WC1+ γδ T cells in peripheral blood and at the sites of MAP infection. Our data suggest that the WC1+ γδ T cell subset may contribute to the immune responses that control MAP infection during the subclinical stage and those that promote disease progression during the terminal stages of MAP infection

Determinants of Capital Structure: the case of MENA countries

This thesis examines the determinants of capital structure in the MENA coun- tries. The main interest is to investigate both financial firms specially banks and non-financial firms. This study test the main theories of capital structure, namely: trade off theory and pecking order theory. The countries included in this thesis are Saudi Arabia, United Arab Emirates (Include both Abo-Dhabi and Dubai stock indexes), Bahrain, Qatar, Kuwait, Oman, Egypt, Morocco, Tunisia, Palestine and Jor- dan. The characteristics it covers as suggested by previous literature are tangibility, profitability, risk, debt tax shield, growth, dividends,size, cash flow and liquidity. It will also investigate the effect of the industry, credit rating and ownership structure on the capital structure This study also investigates the determinants of capital structure in Islamic and conventional banks. This is one of the first attempts to empirically examine the determinants of capital structure in Islamic and conventional banks in general and in MENA countries in particular. This study fills the gap in this important area of research and can provide a base for future research on capital structure in Islamic banks. This thesis use different models to test the capital structure and these are Panel data models (OLS, Fixed, and Random); Tobit and Dynamical model (Arellano-Bover Blundell-Bond), Structural Equation Modeling (SEM) and Generalised Regression Neural Networks (GRNN). The results suggest that the three methods used in this study lead to similar re- sults with a few exceptions in some countries. This thesis finds that the relation between leverage and the determinants of capital structure is different when using the market or the book leverage. It also finds that the determinants of capital struc- ture between the MENA countries are different. For example, profitability attribute relation with leverage follow the trade-off theory in some countries and follow the picking order theory in other countries. Also, liquidity is significant in all the countries in the sample and have a negative relation to leverage. In addition, tangibility is found to have a mixed results with some countries following the trade-off theory and other countries which follow the trade-off theory but overall it is a key determinant of capital structure. Additionally, the findings show that although that the majority of firms in the MENA countries don’t pay dividends the relation between the long term debt and leverage is negative in all the countries in the sample. The growth opportunities have a negative relation in Bahrain, Egypt, Jordan, Kuwait, Morocco, Palestine, Qatar and Tunisia but positive in rest of the countries. The cash flow attribute have a negative relation with leverage in all the countries in the sample except Saudi Arabia and Qatar when using the short and long term debt. Furthermore, the ownership variable is expected to have a negative relation when the ultimate owner is an institution. The results show that overall when there is an ultimate owner the leverage will have a negative relation. Suggesting that ultimate owners will force managers to keep a low debt in firms capital structure. This PhD also attempt to investigate the capital structure in banks within the MENA countries. A special focus is on the differences between the Islamic banks and conventional banks capital structure. First, the findings show that the banks follow the same determinants of capital structure as non-financial firms and that regulations are not the main determinant of capital structure in banks. Then, This study show that there is a difference in capital structure of Islamic banks in com- parison with conventional banks. The findings for the dividends variable show that Islamic banks do not follow the pecking order theory but conventional banks don’t. The results of the size variable show that when Islamic banks are large they use less debt in their capital structure. Growth variable show mixed results depending on the use of book or market leverage. Ownership structure show that when there is an ultimate owner leverage increase which is the reverse of the relation in the non-financial firms. The age variable is negative in relation to the book leverage and positive with the market leverage. Also, credit rating relation is different between the two banks, as it is positive with the conventional banks and negative with Islamic banks. Therefore, this study conclude that the main capital structure theories are applicable to MENA countries. Also indicate that Islamic banks have a different capital structure to conventional banks.Saudi Electronic Universit

The effect of twitter dissemination on cost of equity: A big data approach

Reducing information asymmetry between investors and a firm can have an impact on the cost of equity, especially in an environment or times of uncertainty. New technologies can potentially help disseminate corporate financial information, reducing such asymmetries. In this paper we analyse firms’ dissemination decisions using Twitter, developing a comprehensive measure of the amount of financial information that a company makes available to investors (iDisc) from a big data of firms’ tweets (1,197,208 tweets). Using a sample of 4131 firm-year observations for 791 non-financial firms listed on the US NASDAQ stock exchange over the period 2009–2015, we find evidence that iDisc significantly reduces the cost of equity. These results are pronounced for less visible firms which are relatively small in size, have a low analyst following and a small number of investors. Highly visible firms are less likely to benefit from iDisc in influencing their cost of equity as other communication channels may have widely disseminated their financial information. Our investigations encourage managers to consider the benefits of directly spreading a firm’s financial information to stakeholders and potential investors using social media in order to reduce firm equity premium (COE)

Three-dimensional image classification using hierarchical spatial decomposition: A study using retinal data

This thesis describes research conducted in the field of image mining especially volumetric image mining. The study investigates volumetric representation techniques based on hierarchical spatial decomposition to classify three-dimensional (3D) images. The aim of this study was to investigate the effectiveness of using hierarchical spatial decomposition coupled with regional homogeneity in the context of volumetric data representation. The proposed methods involve the following: (i) decomposition, (ii) representation, (iii) single feature vector generation and (iv) classifier generation. In the decomposition step, a given image (volume) is recursively decomposed until either homogeneous regions or a predefined maximum level are reached. For measuring the regional homogeneity, different critical functions are proposed. These critical functions are based on histograms of a given region. Once the image is decomposed, two representation methods are proposed: (i) to represent the decomposition using regions identified in the decomposition (region-based) or (ii) to represent the entire decomposition (whole image-based). The first method is based on individual regions, whereby each decomposed sub-volume (region) is represented in terms of different statistical and histogram-based techniques. Feature vector generation techniques are used to convert the set of feature vectors for each sub-volume into a single feature vector. In the whole image-based representation method, a tree is used to represent each image. Each node in the tree represents a region (sub-volume) using a single value and each edge describes the difference between the node and its parent node. A frequent sub-tree mining technique was adapted to identified a set of frequent sub-graphs. Selected sub-graphs are then used to build a feature vector for each image. In both cases, a standard classifier generator is applied, to the generated feature vectors, to model and predict the class of each image. Evaluation was conducted with respect to retinal optical coherence tomography images in terms of identifying Age-related Macular Degeneration (AMD). Two types of evaluation were used: (i) classification performance evaluation and (ii) statistical significance testing using ANalysis Of VAriance (ANOVA). The evaluation revealed that the proposed methods were effective for classifying 3D retinal images. It is consequently argued that the approaches are generic

Beekeeping and colony losses in Saudi Arabia

The most commonly managed honey bee is Apis mellifera, a highly adaptable species found almost worldwide and a highly valuable pollinator of agricultural crops. The total number of managed honey bee colonies worldwide was reported to have increased by 64% from 1961 to 2007. However Europe, North America, and some other parts of the world have since 2006/7 observed sharp declines of managed honey bee colonies. A series of surveys reported that many colonies suddenly disappeared, leaving no or only a few remaining living bees, referred to as "Colony Depopulation Syndrome" (CDS) or "Colony Collapse Disorder" (CCD). Various reported possible causes include parasitic mites, malnutrition, harsh winters, exposure to neonicotinoid pesticides, or a combination of these. No single factor has gained widespread acceptance. The research network COLOSS (Prevention of honeybee COlony LOSSes) was formed in 2008, to investigate honey bee colony losses, and carries out annual loss monitoring surveys in many countries in Europe and beyond. However, CCD has not yet been reported in the Arabian Peninsula and colony loss data are limited. Honey bee races in the Arabian Peninsula are morphologically dissimilar to the European honey bee, use of agricultural pesticides there is low, and infestation by Varroa and other pests is less prevalent. Therefore, investigation of colony losses in the Arabian Peninsula will add to the body of research into causes of colony losses. This work is amassing information on the nature and infrastructure of beekeeping in Saudi Arabia, with the aim of establishing a new survey of beekeepers there to study beekeeping management and experience of colony losses. Results so far will be reported

The Effect of Twitter Dissemination on Cost of Equity: Evidence from Financial and Carbon Information

Ph. D. ThesisThe recent development of communication technology through social media, more particularly Twitter, has changed the way that firms communicate with investors. This channel has created an opportunity for firms to disseminate their information to investors on a real-time basis directly. This thesis aims to investigate whether firms can influence their cost of equity (COE) by broadly disseminating their information over Twitter. Employing a sample of non-financial firms with a Twitter account, listed on the US NASDAQ stock exchange over the period 2009-2015, the thesis comprises several objectives. The first objective investigates the effect of firms’ dissemination of financial information (iDisc) over Twitter on the cost of equity. The results find evidence that firms’ dissemination of financial information over Twitter (iDisc) significantly reduces the cost of equity. These results are pronounced for less visible firms that are relatively small in size, have a low analyst following and a small number of investors. Highly visible firms are less likely to benefit from iDisc influencing their cost of equity as other communication channels may have widely disseminated their financial information. Additionally, further tests are employed to investigate the influence of news magnitude on the examined relationship. The findings of the additional tests show a significant negative association between iDisc and cost of equity. The second objective is to investigate whether firms’ dissemination of carbon-related information over Twitter, referred to as iCarbon, influences their cost of equity. The study finds that iCarbon is significantly and negatively associated with COE. Also, additional tests are applied to investigate whether Bloomberg's environmental (ENV) and environmental, social and governance (ESG) disclosure scores influence the relationship between iCarbon and cost of equity. The findings show a consistent negative association between iCarbon and cost of equity after determining the effect of ENV and ESG score. The findings of the thesis encourage managers to consider the benefits of directly disseminating financial and carbon information to stakeholders and potential investors over Twitter to reduce firm equity financing.Saudi Cultural Bureau and King Faisal Universit

Modelling methodologies to assess glucose metabolism in type 2 diabetes

The aetiology and pathogenesis of type 2 diabetes (T20) are yet to be fully understood. However, there is a degree of agreement that the most important pathological factors of T20 are p-cell dysfunction and insulin resistance. Moreover T2D is characterised by varying degrees of impaired pancreatic p-cell responsiveness and/or insulin resistance. The ability to easily quantify insulin sensitivity is useful for investigating the role of impaired insulin secretion and action in the pathophysiology ofT2D. The current work provided novel knowledge in both clinical and methodological areas. On the clinical side, it provided new information about pathology of T2D. On the methodological side, it assessed validity, performance, and/or reproducibility of two powerful models to assess insulin responsiveness and sensitivity. The aim was to use modelling techniques employing data collected during tolerance tests to progress our understanding of pathology of type 2 diabetes. This research evaluated and/or validated two approaches namely, the insulin secretion model and the minimal model, respectively, to assess pancreatic p-cell responsiveness and insulin sensitivity. These methods were then applied to study the aetiology and pathology of T2D on its first clinical appearance (newly diagnosed SUbjects). The insulin secretion model was assessed with two reduced sampling schemes. The model was validated during the oral glucose tolerance test (OGTT). and its performance was compared during OGTT and the meal tolerance test (Mm. The reproducibility of the model indices was also assessed during MTT and OGTT. The one and two compartmental minimal model performance was evaluated and compared to the clamp in subjects with T20. The insulin secretion model and the one compartment minimal model were then applied to study newly presenting T2D in order to gain more understanding of the disease pathology. The output results showed the ability of these approaches to explain the inter-individual variability of important glucose clinical measures such as FPG and HbA1C• In conclusion the insulin secretion model and the one compartment minimal model demonstrated their validity and utility in assessing insulin sensitivity and p-cell responsiveness to provide better Wlderstanding of type 2 diabetes