The impact of avian influenza on the Korean egg market: Who benefited?

The historical decomposition and directed acyclic graph methods are employed to estimate the effect of avian influenza in Korea on egg price transmission between the farm, wholesale, and retail levels. Our findings suggest that farm and retail egg prices are connected by the wholesale price. We also find that the farm-wholesale and the wholesale-retail margins increase during the avian influenza period. Our results imply that the retailer and wholesaler use their market power to increase their price during the food safety crisis. Therefore, the Korean government should control market power by allowing more emergency egg imports.     

Brownian–Laplace Motion and Its Use in Financial Modelling

Brownian-Laplace motion is a Lévy process which has both continuous (Brownian) and discontinuous (Laplace motion) components. The increments of the process follow a generalized normal Laplace (GNL) distribution which exhibits positive kurtosis and can be either symmetrical or exhibit skewness. The degree of kurtosis in the increments increases as the time between observations decreases. This and other properties render Brownian-Laplace motion a good candidate model for the motion of logarithmic stock prices. An option pricing formula for European call options is derived and it is used to calculate numerically the value of such an option both using nominal parameter values (to explore its dependence upon them) and those obtained as estimates from real stock price data.     

清教文化的性别形而上学： 对萨勒姆审巫案的诠释性解释

本文参照行动的文化结构化理论来解释北美历史上最大规模的猎巫事件--萨勒姆审巫案。对该案如何以及何以发生的理解与解释,需要考虑当时活跃在清教徒生活中复杂且被深刻感知的意义。本文揭示了清教文化中的危机。这场造成19个英国男女被绞死的审巫案是在原告、牧师及法官的主导下进行的,他们深植于一个充满意义的世界观中,操纵这一世界观,并最终借助合法暴力捍卫这一世界观。这个世界观是根据如下的紧张与矛盾节点而得以重建的：妇女在社会中的地位、殖民地与上帝之间的关系、世界如何运转的形而上信仰（如巫术与驱魂）。研究萨勒姆审巫案牵涉文化、诠释以及社会学解释的问题。为了回答这些问题,本文指出:（1）文化社会学的解释包含且不限于叙事性意向、意识、言说的意义及行动者的策略;（2）文化社会学的解释应把符号结构与政治经济学的互相嵌入纳入考虑范畴,但又注意不将前者化约为后者;（3）一个危机或事件的走势与参与其中的人们对危机的诠释之间相互纠缠。这意味着,文化社会学能够给出对社会生活的一种因果性诠释,从而超越在理解与解释之间长久存在的区分。     

The competitive advantage potential of vertical integration

There is a widely held belief that backward vertical integration provides firms with the potential for a low-cost competitive advantage, and forward vertical integration provides them with the potential for a differentiation advantage. This study builds theory that underpins that belief, and then tests the theory using a sample of large firms. While our findings do not support the relationship between backward vertical integration and low cost, they do provide strong support for arguments linking forward vertical integration with differentiation-based competitive advantage.     

Examining the Effects of Feedback Accuracy and Timing on Skill Acquisition

ABSTRACT

Feedback involves providing information about past performance and indicating how to improve future performance. Although the literature contains numerous examples of feedback as an effective method for improving performance across a range of organizational settings, much remains unknown about the specifics of how feedback acts to change behavior. This study evaluated the combined effects of feedback accuracy (100%, 80%, 20%) and timing (feedback following each trial or after a block of 25 trials) on skill acquisition in undergraduate students when presented with a computerized match-to-sample task that required participants to learn the names of shapes. Results reveal that feedback accuracy had a significantly greater effect on performance than the timing of the feedback.     

An Ecological Risk Assessment of Nonnative Boas and Pythons as Potentially Invasive Species in the United States

The growing international trade in live wildlife has the potential to result in continuing establishment of nonnative animal populations in the United States. Snakes may pose particularly high risks as potentially invasive species, as exemplified by the decimation of Guam's vertebrate fauna by the accidentally introduced brown tree snake. Herein, ecological and commercial predictors of the likelihood of establishment of invasive populations were used to model risk associated with legal commercial imports of 23 species of boas, pythons, and relatives into the United States during the period 1989-2000. Data on ecological variables were collected from multiple sources, while data on commercial variables were collated from import records maintained by the U.S. Fish and Wildlife Service. Results of the risk-assessment models indicate that species including boa constrictors (Boa constrictor), ball pythons (Python regius), and reticulated pythons (P. reticulatus) may pose particularly high risks as potentially invasive species. Recommendations for reducing risk of establishment of invasive populations of snakes and/or pathogens include temporary quarantine of imports to increase detection rates of nonnative pathogens, increasing research attention to reptile pathogens, reducing the risk that nonnative snakes will reach certain areas with high numbers of federally listed species (such as the Florida Keys), and attempting to better educate individuals purchasing reptiles.     

Emotions in context: Revolutionary accelerators,hope, moral outrage,and other emotions in the making of Nicaragua's revolution

Building on the social movement/revolutions and recent social movement emotions literature and using interviews and oral history from revolutionary Nicaragua, I make a case for recognizing the significance of emotions when studying revolutions. The essay aims for a contextual understanding of the role of emotions in the making of revolution during the insurrectionary period in Nicaragua. These are examined from the vantage point of revolutionary accelerators the conflictual event-contexts from which revolutionary actors emerge. Through the historical analysis of testimonies associated with a number of politically significant events that changed the course of political dynamics in 1970s Nicaragua, the piece illustrates: (1) how events function as generators of revolutionary action and (2) how event-related emotions such as anger and fear, but primarily moral outrage and hope, contribute to a transformation in consciousness that leads potential participants to define their circumstances as needing their revolutionary involvement. It also attempts to demonstrate how the latter two emotions—moral outrage and hope—are dominant under different event-contexts. Lastly, the relationships between these emotions and how these are connected to revolutionary accelerators are similarly explored.     

Measuring college students' alcohol consumption in natural drinking environments: field methodologies for bars and parties

In recent years researchers have paid substantial attention to the issue of college students' alcohol use. One limitation to the current literature is an over reliance on retrospective, self-report survey data. This article presents field methodologies for measuring college students' alcohol consumption in natural drinking environments. Specifically, we present the methodology from a large field study of student drinking environments along with some illustrative data from the same study. Field surveys, observational methods, sampling issues, and breath alcohol concentration sample collection are detailed.