Two essays on managerial risk-seeking activities and compensation contracts

textThis dissertation examines how the structures of compensation for executives and directors are affected by the possibility that managers can influence the risk of a firm's cash flows. In chapter 1, I consider a moral hazard model which shows that a strong pay-for-performance sensitivity in managerial compensation may deteriorate shareholder value when shareholders cannot monitor managerial risk-seeking activities. Intuitively, while high-powered managerial compensation provides the manager with incentives to increase the firm's value by exerting effort, it also creates managerial incentive to engage in (unproductive) risk-seeking activities. To test this prediction, I consider a regulatory change that makes it more difficult for managers to conceal information about the (speculative) use of derivative instruments. Specifically, I examine how the structures of compensation for executives and managers are affected by the adoption of a new accounting standard, the Statement of Financial Accounting Standard No. 133 Accounting for Derivative Instruments and Hedging Activities (FAS 133) which mandates the fair value accounting for derivative holdings. Consistent with the model prediction, I find that relative to other firms, derivative users (firms that traded derivatives before adopting FAS 133) increase the pay-for-performance sensitivity of CEO/CFO compensation. In Chapter 2, I extend the model by incorporating the realistic features that shareholders delegate to the (self-interested) board the tasks of monitoring managers and of setting their compensation contracts. My analysis shows that while high-powered board compensation induces the board to monitor the firm and to properly design managerial compensation, it also provides the board with incentives to misreport managerial risk-seeking activities and to engage in collusive behavior with the manager at the expense of shareholders. From these trade-offs, I develop a number of testable hypotheses and take them to the data. Consistent with the model predictions, I find that firms in which (i) managerial risk-seeking activities are more likely to occur (e.g., high R&D firms or banks) and (ii) board monitoring costs are likely to be lower (e.g., firms that have non-officer blockholders on the board) show weaker pay-for-performance sensitivity of board compensation and stronger pay-for-performance sensitivity of CEO compensation.Financ

Photon-Assisted Quasiparticle Transport and Andreev Transport through an Interacting Quantum Dot

Resonant tunneling through a quantum dot coupled to superconducting reservoirs in the presence of time-dependent external voltage has been studied. A general formula of the current is derived based on the nonequilibrium Green's function technique. Using this formula photon-assisted quasiparticle transport has been investigated for the quantum dot connected to superconductors. In addition, resonant Andreev transport through a strongly correlated quantum dot connected to a normal metallic lead and a superconducting lead is studied.Comment: 9 pages(1 column) with 3 figure

Radio Protective Effects of Ginseng Extract in Gamma-Rays Induced Chromosomal Damages of Human Lymphocyte

Ginsan, a polysaccharide extracted from Panax ginseng and subsequently referred as ginseng, posses various biological properties as an anticancer and antioxidant agent. Ginseng also approved effective against radiation effects through its immunomodulating actions in whole body irradiated mouse. But its protective effects on radiation induced DNA damage are not thoroughly investigated, mainly in human. This experiment aimed to assess the effects of ginseng at 2 working doses in suppressing radiation effects of human peripheral blood lymphocyte (PBL) i.e. chromosome aberration and micronuclei yields. The treatment times were 24 hours before, subsequently (0 hour) or 3 hours after and irradiation with gamma rays at doses of 0.5 - 2.0 Gy (dose rate of 3.16 Gy/min). Treated and untreated blood cultivation and metaphase spreading technique was done according to standard procedures. Results showed that without ginseng treatments, radiation significantly increased dicentrics and micronuclei frequencies. Different with the results in mouse study, however, our results indicated that none of the experimental concentrations of ginseng crude water extract tested had an effect on baseline chromosomal aberration and micronuclei (MN) yields in PBL. A protective effect was only seen in chromosome aberration yields of sample irradiated with 2.0 Gy and treated with ginseng 3 h post irradiation rather than 24 h pre-irradiation in one volunteer. Opposite results that ginseng suspected to be a weak radiosensitizer was found in some cases. This may be due to discrepancies exist in route of treatment and its fundamental mechanisms of protective action between both studies. Even though in general it was not effective, the possible mechanism involved in radioprotective influence of ginseng is discussed

Spin Fluctuation and Persistent Current in a Mesoscopic Ring Coupled to a Quantum Dot

We investigate the persistent current influenced by the spin fluctuations in a mesoscopic ring weakly coupled to a quantum dot. It is shown that the Kondo effect gives rise to some unusual features of the persistent current in the limit where the charge transfer between two subsystems is suppressed. Various aspects of the crossover from a delocalized to a localized dot limit are discussed in relation with the effect of the coherent response of the Kondo cloud to the Aharonov-Bohm flux.Comment: 4 pages, 2 figure

Risk Factors for Recurrence of Symptomatic Common Bile Duct Stones after Cholecystectomy

Purpose. The recurrence of CBD stone is still observed in a considerable number of patients. The study was to evaluate the risk factors for recurrence of symptomatic CBD stone in patients who underwent cholecystectomy after the removal of CBD stone. Methods. The medical records of patients who underwent removal of CBD stone with subsequent cholecystectomy were reviewed. The risk factors for the recurrence of symptomatic CBD stone were compared between the recurrence and the nonrecurrence group. Results. The mean follow-up period was 40.6 months. The recurrence of symptomatic CBD stones was defined as the detection of bile duct stones no sooner than 6 months after complete clearance of CBD stones, based on symptoms or signs of biliary complication. 144 patients (68 males, 47.2%) were finally enrolled and their mean age was 59.8 (range: 26~86) years. The recurrence of CBD stone occurred in 15 patients (10.4%). The mean period until first recurrence was 25.9 months. The presence of type 1 or 2 periampullary diverticulum and multiple CBD stones were the independent risk factors. Conclusion. For the patients with type 1 or 2 periampullary diverticulum or multiple CBD stones, careful followup is needed for the risk in recurrence of symptomatic CBD stone

Clinical Significance of Colonic Diverticulosis Associated with Bowel Symptoms and Colon Polyp

This study was done to evaluate prospectively the clinical significance of colonic diverticulosis. In the 1,030 consecutive outpatients undergoing colonoscopy, the information on the demographics, the patterns of bowel symptoms, and the prevalence of colon polyp were analyzed according to the presence of colonic diverticulosis. The mean age of 1,030 patients were 52.2 yr and 59.3% were male. The prevalence of diverticulosis was 19.7% (203/1,030). Of 203 diverticulosis patients 85.2% were in proximal group, 5.4% in distal group and 9.4% in both group. Six (3.0%) patients were found to have diverticulitis. Multivariate logistic regression analysis showed that an old age, diabetes and the presence of polyp were significant factors associated with proximal or both diverticulosis. A significant difference was demonstrated between the patients of distal diverticular group and the controls for the symptom frequency scores within the previous 4 weeks. The items, which showed difference, were hard stool, urgency, flatus, chest discomfort and frequent urination. In conclusion, old age, diabetes and the presence of colon polyp were associated with proximal diverticulosis. The temporal symptoms were more frequent in distal diverticulosis than in proximal diverticulosis in the study subjects

Simultaneous Colonic Obstruction and Hydroureteronephrosis due to Mesenteric Fibromatosis

Mesenteric fibromatosis (MF) is a rare benign mesenchymal lesion that can occur throughout the gastrointestinal tract, especially small bowel. Its biological behavior is intermediate between benign fibrous tissue proliferation and malignant fibrosarcoma. In previously reported cases of MF, we could find colonic obstruction or ureter obstruction, but simultaneous involvement of colon and ureter was not able to be seen. We described a patient that presented with colonic obstruction and hydroureteronephrosis due to MF at sigmoid colon which mimicked submucosal tumor such as gastrointestinal tumor. This case resulted in a positive positron emission tomography scan suggesting malignant neoplasm, but β-catenin positivity on immunohistochemical staining separated MF from gastrointestinal stromal tumor and sclerosing mesenteritis. The clinical course of the patient was improved after surgical resection