The valuation effect and determinants of corporate contracting : a thesis presented in partial fulfillment of the requirements for a Master of Business Studies at Massey University, December 2002

This study examined abnormal stock market returns to equity holders around corporate contract announcement that were obtained from Dow Jones & Company, Inc. between January 1, 1990 and December 31, 2000. Of the 7137 contract announcement found, 984 contract winning companies (contractee) and 575 contract giving companies (contractor) were not contaminated by other announcements and have sufficient CRSP data to enter the final sample that was analyzed for excess returns to the contractees. Excess returns were also analyzed for the contractors. The Asymmettic Information Hypothesis and Information Content Hypothesis were used to develop hypotheses that predict contract announcement abnormal returns. The Market Model was used to analyze abnormal returns for both the contractees and contractors. As expected, statistically significant cumulative average excess returns were found for contractee companies, but not for contractor companies. Contractee excess returns were also examined for different industry groups. Also, the international or domestic nature of the contractor is analyzed for differences in abnormal returns. Contrary to expectations, the market reacted with more significant abnormal return for domestic contracting than the international contracting. Finally, cross-sectional regression models are developed to test the statistical significance of variables relative to sample characteristic, firm size, profitability, and information asymmetries of firm. Contractee relative contract size was found to have significant impact on cumulative average abnormal returns. Dummy variables were included in the cross-section model to account for the sequence of the contract and nationality of the contractee and contractor, but they were statistically insignificant to the model. The variables for contractor's firm were also statistically insignificant in effecting abnormal returns for their equity

751-5 Rapid Angiographic Progression of “Target” and “Non-target” Stenoses in Patients Awaiting Coronary Angioplasty

Coronary angioplasty (PTCA) is effective therapy for angina pectoris but coronary events occur after successful PTCA which may be caused by both restenosis and progression of mild pre-existing, “non-target”, stenoses. To compare the short-term evolution of “target”versus “non-target”stenoses in patients awaiting PTCA, we prospectively studied 161 consecutive stable angina patients (124 men and 37 women). After diagnostic angiography, “target”stenoses for PTCA and “non-target”lesions were identified. Patients were put on a routine waiting list and followed up regularly until repeat coronary arteriography (mean±SD: 7±3 months). which was performed immediately preceding angioplasty (138 patients) or soon after acute coronary events (23 patients) when these occurred. Stenosis diameters were measured using computerized arteriography. Progression was defined as 2:20% diameter reduction, new total occlusion, or development of “new” stenoses 2:30%. At study entry, diameters of target (n=207) and non-target (n=184) lesions were 68±9% and 38±9%, respectively (p < 0.001). Disease progression occurred in 33 patients (20%). in whom 18 target (9%) and 15 nontarget stenoses (8%) progressed and 7 new lesions (1 total occlusion) developed. Total occlusion developed in 15 of the 18(83%) target and in 6 of the 15 (40%) non-target stenoses; (p=0.03). During follow up, 3 patients (2%) had a myocardial infarction and 20 (12%) developed unstable angina. These events were associated with progression of target stenoses in 10 patients, of non-target stenoses in 7 patients, and with new lesions in one patient. In 5 patients events were not associated with stenosis progression.Thus a similar proportion of target and non-targetlesions progressed rapidly. Targetstenoses, however, were more likely to progress to total occlusion than non-targetlesions. Progression of non-targetstenoses may contribute to recurrence of angina and new coronary events after successful angioplasty and their role should be considered when developing strategies aimed at improving survival after angioplasty

Risk Assessment of Nautical Navigational Environment Based on Grey Fixed Weight Cluster

In order to set up a mathematical model suitable for nautical navigational environment risk evaluation and systematically master the navigational environment risk characteristics of the Qiongzhou Strait in a quantitative way, a risk assessment model with approach steps is set up based on the grey fixed weight cluster (GFWC). The evaluation index system is structured scientifically through both literature review and expert investigation. The relative weight of each index is designed to be obtained via fuzzy analytic hierarchy process (FAHP); Index membership degree of every grey class is proposed to be achieved by fuzzy statistics (FS) to avoid the difficulty of building whiten weight functions. By using the model, nautical navigational environment risk of the Qiongzhou Strait is determined at a “moderate” level according to the principle of maximum membership degree. The comprehensive risk evaluation of the Qiongzhou Strait nautical navigational environment can provide theoretical reference for implementing targeted risk control measures. It shows that the constructed GFWC risk assessment model as well as the presented steps are workable in case of incomplete information. The proposed strategy can excavate the collected experts’ knowledge mathematically, quantify the weight of each index and risk level, and finally lead to a comprehensive risk evaluation result. Besides, the adoptions of probability and statistic theory, fuzzy theory, aiming at solving the bottlenecks in case of uncertainty, will give the model a better adaptability and executability.</p

Alleviating Behavior Data Imbalance for Multi-Behavior Graph Collaborative Filtering

Graph collaborative filtering, which learns user and item representations through message propagation over the user-item interaction graph, has been shown to effectively enhance recommendation performance. However, most current graph collaborative filtering models mainly construct the interaction graph on a single behavior domain (e.g. click), even though users exhibit various types of behaviors on real-world platforms, including actions like click, cart, and purchase. Furthermore, due to variations in user engagement, there exists an imbalance in the scale of different types of behaviors. For instance, users may click and view multiple items but only make selective purchases from a small subset of them. How to alleviate the behavior imbalance problem and utilize information from the multiple behavior graphs concurrently to improve the target behavior conversion (e.g. purchase) remains underexplored. To this end, we propose IMGCF, a simple but effective model to alleviate behavior data imbalance for multi-behavior graph collaborative filtering. Specifically, IMGCF utilizes a multi-task learning framework for collaborative filtering on multi-behavior graphs. Then, to mitigate the data imbalance issue, IMGCF improves representation learning on the sparse behavior by leveraging representations learned from the behavior domain with abundant data volumes. Experiments on two widely-used multi-behavior datasets demonstrate the effectiveness of IMGCF.Comment: accepted by ICDM2023 Worksho

Differential progression of complex and smooth stenoses within the same coronary tree in men with stable coronary artery disease

Objectives.We sought to compare the evolution of complex and smooth stenoses within the same coronary tree in patients with stable coronary artery disease.Background.Progression of coronary stenosis has prognostic significance and may be influenced by local and systemic factors. Stenosis morphology is a determinant of disease progression, but no previous study has systematically assessed progression of complex and smooth stenoses within the same patient.Methods.We studied 50 men with stable angina who 1) had one complex coronary stenosis and one smooth stenosis in different noninfarct-related coronary vessels at initial coronary angiography, and 2) had a second angiogram after a median interval of 9 months (range 3 to 24). Patients with lesions ≥10 mm long, at a major branching point or with >85% diameter reduction were not included. Coronary lesions were measured quantitatively from comparable end-diastolic frames. Stenosis morphology was determined qualitatively by two independent observers.Results.All patients remained in stable condition during follow-up. Progression, defined as an increase in diameter stenosis by ≥15% was seen in only eight complex stenoses (16%) but in no smooth lesions (p < 0.01). The severity of complex stenoses changed more than that of corresponding smooth stenoses (mean ± 1 SD 5.8 ± 13% vs. −0.06 ± 6%, p < 0.01). On average, the annual rate of growth was 11.4 ± 28% and 1.5 ± 14% for complex and smooth lesions, respectively (p < 0.01).Conclusions.Few coronary stenoses progress rapidly in stable angina. Complex and smooth coronary stenoses progress at different rates within the same coronary tree. Complex stenosis morphology itself is an important determinant of progression of stenosis in patients with apparently clinically stable coronary artery disease

Ecological Balance of Oral Microbiota is Required to Maintain Oral Mesenchymal Stem Cell Homeostasis

Oral microbiome is essential for maintenance of oral cavity health. Imbalanced oral microbiome causes periodontal and other diseases. It is unknown whether oral microbiome affect oral stem cells function. In this study, we used a common clinical anti-biotic treatment approach to alter oral microbiome ecology and examine whether oral mesenchymal stem cells (MSCs) are affected. We found that altered oral microbiome resulted gingival MSCs deficiency, leading to a delayed wound healing in male mice. Mechanistically, oral microbiome release LPS that stimulates the expression of microRNA-21 (miR-21) and then impair the normal function of gingival MSCs and wound healing process through miR-21/Sp1/TERT pathway. This is the first study indicate that interplay between oral microbiome and MSCs homeostasis in male mice

The Fas/Fap-1/Cav-1 Complex Regulates IL-1RA Secretion in Mesenchymal Stem Cells to Accelerate Wound Healing

Mesenchymal stem cells (MSCs) are capable of secreting exosomes, extracellular vesicles, and cytokines to regulate cell and tissue homeostasis. However, it is unknown whether MSCs use a specific exocytotic fusion mechanism to secrete exosomes and cytokines. We show that Fas binds with Fas-associated phosphatase–1 (Fap-1) and caveolin-1 (Cav-1) to activate a common soluble N-ethylmaleimide–sensitive factor (NSF) attachment protein receptor (SNARE)–mediated membrane fusion mechanism to release small extracellular vesicles (sEVs) in MSCs. Moreover, we reveal that MSCs produce and secrete interleukin-1 receptor antagonist (IL-1RA) associated with sEVs to maintain rapid wound healing in the gingiva via the Fas/Fap-1/Cav-1 cascade. Tumor necrosis factor–α (TNF-α) serves as an activator to up-regulate Fas and Fap-1 expression via the nuclear factor κB pathway to promote IL-1RA release. This study identifies a previously unknown Fas/Fap-1/Cav-1 axis that regulates SNARE-mediated sEV and IL-1RA secretion in stem cells, which contributes to accelerated wound healing