A sonography image processing system for tumour segmentation

ABSTRACT

A sonography image processing system for tumour segmentation is implemented by using the active contour model based on level set formulation. To achieve extraction of weak edges in speckle noisy images, the level set model called Edge Attraction Force on Chan and Vese model is developed. The cell competition algorithm is modified by adding the information of the cells’ edges. Calculus of variation is taken to derive the evolution equation of the active contour. Experiments demonstrate that the boundaries of tumours extracted by the proposed active contour are more accurate for conquering the drawbacks coming from weak edges. Experiments demonstrate that the boundaries of tumors extracted by the proposed active contour are accurate and the results avoid the drawbacks of the weak edges.     

Are single‐gift committed donors different from their multiple‐gift counterparts?

Committed donors who keep giving every year are a key asset for nonprofit organizations because they provide a steady funding source and return a higher lifetime value. We distinguish between committed donors who give only one gift per year (single‐gift (SG) donors) and those who give multiple gifts in at least some year (multiple‐gift (MG) donors). In this paper, we study whether SG donors and MG donors follow different longitudinal patterns of gift‐giving in four consecutive years. We theorize that a donor's yearly gift amount is an indication of his or her willingness to give (WTG) to the organization and may be explained in terms of his or her intrinsic willingness to give (IWTG) and extrinsic willingness to give (EWTG) for that year. We test our theory with data from a leading US nonprofit organization and find that SG donors and MG donors would follow different longitudinal patterns:

• While SG donors and MG donors would start off at a similar level of WTG in year 1 and would both increase WTG in subsequent years, MG donors would record a higher rate of increase than SG donors.
• IWTG and EWTG would have different relative importance as determinants of the observed yearly giving level: MG donors depend on both IWTG and EWTG whereas SG donors largely depend on IWTG rather than EWTG to determine how much to give in a year.

Our findings suggest that different strategies are needed to manage SG donors and MG donors to sustain and grow annual contributions. Copyright © 2009 John Wiley & Sons, Ltd.     

How do Heterogeneous Beliefs Influence Asset Volatility?

We investigate the influence of heterogeneous beliefs on asset volatility when agents' degrees of confidence differ. With a continuous‐time model subsuming agent's heterogeneous beliefs in the expected increase in dividends, a stock price formula is derived. Based on this formula, the stock volatility is computed via Monte Carlo simulation. The results show that the influence of belief heterogeneity in expectation on volatility depends on the confident agents' level of optimism. Empirical results are also provided.     

Effects of managerial overconfidence on analyst recommendations

Review of Quantitative Finance and Accounting - This study investigates the relation between managerial overconfidence and analyst recommendations. The empirical finding shows that analysts are...     

R&D EFFICIENCY AND THE NATIONAL INNOVATION SYSTEM: AN INTERNATIONAL COMPARISON USING THE DISTANCE FUNCTION APPROACH

This paper applies the distance function approach for stochastic frontier analysis (SFA) to compare research and development (R&D) efficiency across 24 nations during 1998–2005. In this multiple input–output framework, R&D expenditure stock and R&D manpower were inputs, while patents, scientific journal articles, and royalties and licensing fees (RLF) were outputs. Intellectual property rights protection, technological cooperation among business sectors, knowledge transfer between business sectors and higher education institutions, agglomeration of R&D facilities, and involvement of the government sector in R&D activities significantly improve national R&D efficiency.     

Subbalanced games and bargaining sets

Summary. In defining a bargaining set, it is desirable to require that a counterobjecting coalition has a non-empty intersection with the objecting coalition. We refer to this as the intersection property and define a bargaining set, MB ₁, that imposes this property on a variant of the bargaining set defined by Vohra (1991). To study the existence of MB ₁, a new version of the KKM theorem is proposed and the concept of a subbalanced game is introduced. We also provide conditions for the non-emptiness of MB ₂, a bargaining set introduced by Zhou (1994) which imposes the additional restriction that the objecting coalition not be a subset of the counterobjecting coalition.Received: 9 December 2002, Revised: 6 December 2004, JEL Classification Numbers: C71. Correspondence to: Chih ChangThe authors are very grateful to a referee who proposes many helpful comments on both substantive matters and exposition which much improve the paper.     

Technological Change,Job Risk,and Wage Premium: Evidence from Taiwan

The paper reports the results of analyzing the effects of technological change and job risk on wage premiums in Taiwan. Using unique individual data combined with industry‐level indices of technological change and fatality rates across industries, the empirical results show that, overall, industries characterized by a higher rate of technological change or fatality pay a higher wage. However, these positive correlations are attributed to the sorting effect in which workers with some specific features choose to find jobs in industries with rapid technological change and higher job risk. Furthermore, this paper reports a positive relationship between education and wages after controlling for individual heterogeneity, showing the existence of education premium in Taiwan.     

The role of market imperfections in the relationship between housing prices and household credit: Evidence from Taiwan

Given the credit market imperfections in Taiwan, this paper examines the threshold effects in the adjustment towards the long‐run equilibrium relationship between housing prices and household credit. The empirical findings verify the potential for regime shifts in the dynamically adjusted relationship between housing prices and household credit. Only when the benefits cover the cost of market imperfections, do housing and credit markets trigger convergence to their long‐run equilibrium. The hidden effect of the limitations on housing and credit markets is to raise the thresholds of the self‐adjustment mechanisms. As a result, economic boom‐bust cycles will be more severe and increase the fragility of financial sectors.     

Pricing of moving‐average‐type options with applications

Moving‐average‐type options are complex path‐dependent derivatives whose payoff depends on the moving average of stock prices. This article concentrates on two such options traded in practice: the moving‐average‐lookback option and the moving‐average‐reset option. Both options were issued in Taiwan in 1999, for example. The moving‐average‐lookback option is an option struck at the minimum moving average of the underlying asset's prices. This article presents efficient algorithms for pricing geometric and arithmetic moving‐average‐lookback options. Monte Carlo simulation confirmed that our algorithms converge quickly to the option value. The price difference between geometric averaging and arithmetic averaging is small. Because it takes much less time to price the geometric‐moving‐average version, it serves as a practical approximation to the arithmetic moving‐average version. When applied to the moving‐average‐lookback options traded on Taiwan's stock exchange, our algorithm gave almost the exact issue prices. The numerical delta and gamma of the options revealed subtle behavior and had implications for hedging. The moving‐average‐reset option was struck at a series of decreasing contract‐specified prices on the basis of moving averages. Similar results were obtained for such options with the same methodology. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:415–440, 2003     

Social network structure and status competition

In status competition studies, the utility of heterogeneous individuals typically depends on an economy‐wide average indicator of status. In our model, emulative and jealous agents are embedded in an exogenous network where agent‐specific reference group is determined by the direct link emanating from the agent. Similarly to Ghiglino and Goyal (2010) but in a somewhat different framework, we show that individual consumption is proportional to the agent's “outbound” Katz‐Bonacich network centrality measure and equilibrium is generally inefficient. More important, the negative externality associated with each agent depends on her “inbound” centrality measure—the conspicuousness index. A tax based on this index combined with a uniform lump‐sum transfer attains efficiency.