Optimal constrained investment in the Cramer-Lundberg model

We consider an insurance company whose surplus is represented by the classical Cramer-Lundberg process. The company can invest its surplus in a risk-free asset and in a risky asset, governed by the Black-Scholes equation. There is a constraint that the insurance company can only invest in the risky asset at a limited leveraging level; more precisely, when purchasing, the ratio of the investment amount in the risky asset to the surplus level is no more than a; and when short-selling, the proportion of the proceeds from the short-selling to the surplus level is no more than b. The objective is to find an optimal investment policy that minimizes the probability of ruin. The minimal ruin probability as a function of the initial surplus is characterized by a classical solution to the corresponding Hamilton-Jacobi-Bellman (HJB) equation. We study the optimal control policy and its properties. The interrelation between the parameters of the model plays a crucial role in the qualitative behavior of the optimal policy. For example, for some ratios between a and b, quite unusual and at first ostensibly counterintuitive policies may appear, like short-selling a stock with a higher rate of return to earn lower interest, or borrowing at a higher rate to invest in a stock with lower rate of return. This is in sharp contrast with the unrestricted case, first studied in Hipp and Plum, or with the case of no short-selling and no borrowing studied in Azcue and Muler.     

The role of stock ownership by US members of Congress on the market for political favors

I examine whether stock ownership by politicians helps to enforce noncontractible quid pro quo relations with firms. The ownership by US Congress members in firms contributing to their election campaigns is higher than in noncontributors. This bias toward contributors depends on the financial incentives of politicians and the relation's value. Firms with a stronger ownership–contribution association receive more government contracts. The financial gains from these contracts are economically large. When politicians divest stocks, firms discontinue contributions to the politicians, lose future contracts, and perform poorly. Politicians divest the stocks in contributors, but not in noncontributors, in anticipation of retirement.     

The role of banks in the governance of nonfinancial firms: Evidence from Europe

The aim of our research is to investigate the important role of banks in the governance of companies listed in the Euronext 100 index. Primarily, this research seeks to examine the impact of a bank’s presence within a firm, as a creditor or shareholder, on firm performance, as well as the motivations of banks to acquire holdings, and whether the presence of a bank as a shareholder of a firm facilitates its access to bank loans. Empirical analyses are conducted with a sample of 86 nonfinancial institutions listed in the Euronext 100 index over the period 2008–2013 using the three-stage least squares method. The study shows, first, that the presence of a bank within a firm, as a creditor or shareholder, is positively related to firm performance. Moreover, the firm’s performance is an important determinant of the presence of bank shareholding. Finally, the presence of a bank as a shareholder of a firm does not facilitate its access to bank loans.     

Information congruity in scarcity appeal: A structural equation modeling study of time-limited promotions

Although market scarcity such as time restriction is widely used in retail advertisements, its impact on product message processing and product evaluation is still subject to controversy. In this study, analyses through structural equation modeling indicated that (i) scarcity had no impact on product message processing, (ii) scarcity had a direct impact on product evaluation as a heuristic cue when the value inferred from scarcity was congruous with the worth derived from product message, and (iii) scarcity lost its impact on product evaluation when the value inferred from scarcity was incongruous with the worth derived from product message, and the incongruity prompted scrutiny of product message, resulting in a mediated impact of product message on product evaluation through product message processing. In conclusion, the results supported an information congruity theory of market scarcity.     

将数学建模引入高等数学教学中的典型案例

首先阐述了将数学建模思想融入高等数学教学内容中的意义,接着从高等数学中的基本概念和基本定理出发,通过具体案例说明如何将数学建模案例融入在高等数学教学中。最后给出了根据高等数学内容选编的典型建模案例。     

Forecasting technology diffusion: a new generalisation of the logistic model

The present research proposes a new generalisation of the logistic model aiming at technology diffusion forecasting. Regarding criticisms and failures reported in the literature to apply logistic function for long-term forecasting, in our work we focused on short-term accuracy of forecast. To formulate the model, based on mathematical approximation, at first the differential equation governing the diffusion process is found and then by solving the derived differential equation, the forecast function is obtained. In all steps, mathematical tools from numerical analysis are used. We compared the New Generalized Logistic Model with eight of the most renowned models in the literature. The model led to more accurate fits and forecasts than those obtained from other models we applied for comparison.     

Distance-sensitivity of German exports: first evidence from firm-product level data

This article uses a tailor-made new data set of 7 580 251 observations for German exports at the firm-product-destination level to estimate a gravity equation and to investigate the link between the amount of firms’ exports and the distance to destination countries. It is shown that, in line with stylized facts based on aggregate data, the quantity of exports declines significantly with distance within a firm for a given product.     

关于复数运算在高次方程中的运用

随着office2010版开发,复数函数的运算的完善为高次方程的完整解提供了技术上的有力保障。     

72205综采工作面3300V高压供电技术改造

随着工作面功率的加大,矿井电压过低造成设备启动困难或不启动现象,甚至造成欠电压跳闸,因此1140V电压等级升高到3300V将是煤矿发展的前进方向。     

Moderating Role of Gender in the Relationship between Hotel Service Quality Dimensions and Tourist Satisfaction

Gender has frequently been identified as one of the key attributes and predictors in developing marketing strategy. This study examines the moderating role of gender in the relationship between hotel service quality dimensions and tourist satisfaction with hotel service delivery. The results derived from multi-group structural equation modeling via the AMOS 5.0 computer program revealed that gender significantly moderated the relationship between service quality dimensions and tourist satisfaction with hotel service delivery. Empathy and tangibles both contributed as the most important significant predictors of tourist satisfaction with hotel service delivery for male tourists as opposed to female tourists. It is statistically confirmed that men and women appear to respond to different aspects of a service encounter when making judgments about their satisfaction.