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Several Empirical Studies (several + empirical_studies)
Selected AbstractsRECONSTRUCTING PLUMAGE EVOLUTION IN ORIOLES (ICTERUS): REPEATED CONVERGENCE AND REVERSAL IN PATTERNSEVOLUTION, Issue 6 2000Kevin E. Omland Abstract. Several empirical studies suggest that sexually selected characters, including bird plumage, may evolve rapidly and show high levels of convergence and other forms of homoplasy. However, the processes that might generate such convergence have not been explored theoretically. Furthermore, no studies have rigorously addressed this issue using a robust phylogeny and a large number of signal characters. We scored the appearance of 44 adult male plumage characters that varied across New World orioles (Icterus). We mapped the plumage characters onto a molecular phylogeny based on two mitochondrial genes. Reconstructing the evolution of these characters revealed evidence of convergence or reversal in 42 of the 44 plumage characters. No plumage character states are restricted to any groups of species higher than superspecies in the oriole phylogeny. The high frequency of convergence and reversal is reflected in the low overall retention index (RI = 0.66) and the low overall consistency index (CI = 0.28). We found similar results when we mapped plumage changes onto a total evidence tree. Our findings reveal that plumage patterns and colors are highly labile between species of orioles, but highly conserved within the oriole genus. Furthermore, there are at least two overall plumage types that have convergently evolved repeatedly in the three oriole clades. This overall convergence leads to significant conflict between the molecular and plumage data. It is not clear what evolutionary processes lead to this homoplasy in individual characters or convergence in overall pattern. However, evolutionary constraints such as developmental limitations and genetic correlations between characters are likely to play a role. Our results are consistent with the belief that avian plumage and other sexually selected characters may evolve rapidly and may exhibit high homoplasy. The overall convergence in oriole plumage patterns is an interesting evolutionary phenomenon, but it cautions against heavy reliance on plumage characters for constructing phylogenies. [source] Classification System for English Language Learners: Issues and RecommendationsEDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 3 2008Jamal Abedi High-stakes decisions for the instruction and assessment of English language learner (ELL) students are made based on the premise that ELL classification is a valid dichotomy that distinguishes between those who are proficient in the use of the English language and those who are not. However, recent research findings draw a vague picture of the term "ELL" and call for a more valid classification system for ELL students. Thus, the purpose of this paper is twofold: (1) to reveal issues concerning the validity of the current ELL classification system based on the results of several empirical studies, and (2) to initiate a discussion on ways to improve the validity of the ELL classification system by proposing a system that uses existing multiple criteria in a stepwise manner. While the suggested system has its own limitations and controversies, we hope this discussion stimulates thoughts and brings much needed attention to this very important national issue. [source] What is Antidumping Policy Really About?JOURNAL OF ECONOMIC SURVEYS, Issue 4 2000Gunnar Niels Dumping is whatever you can get the government to act against under the antidumping law. J. Michael Finger (1993, p.viii). Antidumping policy has become one of the most important instruments for protection in the international trade system, but at the same time it is the subject of an intense, though rather chaotic, debate. This paper provides an overview of the antidumping literature and the current issues. First it describes the origins of antidumping policy and provides some basic statistics on its current use drawn from several empirical studies. Next the paper discusses the economic foundations of antidumping law by examining the traditional and modern theories of dumping, as well as the industrial organization literature on price discrimination and predatory pricing. It is demonstrated that those economic foundations are weak. The paper also considers the fairness rationales for antidumping policy. Finally, it addresses the criticisms of antidumping laws, in particular in the context of the current antidumping versus competition policy debate, and discusses a variety of proposals for reform that have been made. The paper shows that the 1997 ,cease fire' agreement between Canada and Chile is a promising approach toward reform of antidumping policy. [source] Parasites and deleterious mutations: interactions influencing the evolutionary maintenance of sexJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2010A. W. PARK Abstract The restrictive assumptions associated with purely genetic and purely ecological mechanisms suggest that neither of the two forces, in isolation, can offer a general explanation for the evolutionary maintenance of sex. Consequently, attention has turned to pluralistic models (i.e. models that apply both ecological and genetic mechanisms). Existing research has shown that combining mutation accumulation and parasitism allows restrictive assumptions about genetic and parasite parameter values to be relaxed while still predicting the maintenance of sex. However, several empirical studies have shown that deleterious mutations and parasitism can reduce fitness to a greater extent than would be expected if the two acted independently. We show how interactions between these genetic and ecological forces can completely reverse predictions about the evolution of reproductive modes. Moreover, we demonstrate that synergistic interactions between infection and deleterious mutations can render sex evolutionarily stable even when there is antagonistic epistasis among deleterious mutations, thereby widening the conditions for the evolutionary maintenance of sex. [source] Toward an epistemology of WikipediaJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 10 2008Don Fallis Wikipedia (the "free online encyclopedia that anyone can edit") is having a huge impact on how a great many people gather information about the world. So, it is important for epistemologists and information scientists to ask whether people are likely to acquire knowledge as a result of having access to this information source. In other words, is Wikipedia having good epistemic consequences? After surveying the various concerns that have been raised about the reliability of Wikipedia, this article argues that the epistemic consequences of people using Wikipedia as a source of information are likely to be quite good. According to several empirical studies, the reliability of Wikipedia compares favorably to the reliability of traditional encyclopedias. Furthermore, the reliability of Wikipedia compares even more favorably to the reliability of those information sources that people would be likely to use if Wikipedia did not exist (viz., Web sites that are as freely and easily accessible as Wikipedia). In addition, Wikipedia has a number of other epistemic virtues (e.g., power, speed, and fecundity) that arguably outweigh any deficiency in terms of reliability. Even so, epistemologists and information scientists should certainly be trying to identify changes (or alternatives) to Wikipedia that will bring about even better epistemic consequences. This article suggests that to improve Wikipedia, we need to clarify what our epistemic values are and to better understand why Wikipedia works as well as it does. Somebody who reads Wikipedia is "rather in the position of a visitor to a public restroom," says Mr. McHenry, Britannica's former editor. "It may be obviously dirty, so that he knows to exercise great care, or it may seem fairly clean, so that he may be lulled into a false sense of security. What he certainly does not know is who has used the facilities before him." One wonders whether people like Mr. McHenry would prefer there to be no public lavatories at all. The Economist (Vol. 379, April 22, 2006, pp. 14,15) [source] Communication Flows in International Product Innovation TeamsTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 5 2000Rudy K. Moenaert Recently, we have witnessed a strong growth in the internationalization of many firms' product development activities. However, the lack of attention devoted by scientific research to the management of international innovation contrasts sharply with the importance attached to it as a cornerstone of international business success. Although several empirical studies and normative theories have specified the communication requirements in innovation teams, an empirically based insight is definitely needed on the communication requirements and requirements that prevail in the complex context of international innovation teams, in which the participants are located in different company units, countries, and cultures. This article addresses the following research question: viewing international innovation as an interfunctional activity, what are the communication requirements an international innovation team is facing, and what are the communication capabilities (interface mechanisms) that may be adopted to initiate, develop, and launch the new product effectively and efficiently? An extensive case study research project was designed to develop a comprehensive theoretical framework. Over a two year time period, the research team has investigated selected innovation projects in four European multinational corporations. The analysis of the case study data suggests five requirements that determine the effectiveness and efficiency of communication in international product development teams: network transparency, knowledge codification, knowledge credibility, communication cost, secrecy. To cope with these communication requirements, organizations may create firm level capabilities (parallel structures, cross-functional and inter-unit climate, communication infrastructure, goal congruence) and team level capabilities (core team, team leadership, formalization, procedural justice). The evidence from the in-depth case study research indicates that these mechanisms provide a parsimonious and powerful approach to address the communication requirements in international product innovation teams. After the information processing framework proposed by Tushman and Nadler [124], the adoption of these mechanisms is expected to improve innovation effectiveness. This holds important consequences for the management of international product innovation projects. First, the innovating firm must balance centralization and decentralization, employ formal as well as informal strategies, and integrate ad-hoc and permanent strategies. Second, it highlights the critical role of the project leader. Given the fact that companies often select the most available person, rather than the best person for the job, the allocation of light weight project leaders may create heavyweight problems in international teams. Third, following the argument in favor of procedural justice, the absence of involvement may severely hinder cross-functional commitment to international innovation projects. Fourth, the innovating firm must also actively manage the communication flows with external parties. Failure to do so may result in flawed specifications, and a limited understanding about product design and market strategies. [source] | |||||||||||||