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101.
Mathematical morphology: A useful set of tools for image analysis   总被引:2,自引:0,他引:2  
In this paper we give an overview of both classical and more modern morphological techniques. We will demonstrate their utility through a range of practical examples. After discussing the fundamental morphological ideas, we show how the classic morphological opening and closing filters lead to measures of size via granulometries, and we will discuss briefly their implementation. We also present an overview of morphological segmentation techniques, and the use of connected openings and thinnings will be demonstrated. This then leads us into the more recent set-theoretic notions of graph based approaches to image analysis.  相似文献   
102.
In the paper we present a new method of calculating sampling intervals, so-called windows, allowing an experimenter some flexibility in timing the sample collection, while a minimum required design efficiency for parameter estimation is assured. The method is based on the Equivalence Theorem for D-optimality what makes the length of each window related to the parameter sensitivities. An example of calculating the windows in a pharmacokinetic study is presented. Some other methods of calculating efficient sampling windows are briefly discussed.  相似文献   
103.
We develop statistical inferential tools for estimating and comparing conditional tail expectation (CTE) functions, which are of considerable interest in actuarial science. In particular, we construct estimators for the CTE functions, develop the necessary asymptotic theory for the estimators, and then use the theory for constructing confidence intervals and bands for the functions. Both parametric and non-parametric approaches are explored. Simulation studies illustrate the performance of estimators in various situations. Results are obtained under minimal assumptions, and the general Vervaat process plays a crucial role in achieving these goals.  相似文献   
104.
A paucity of research has examined the individual and cumulative effects of conventional and expanded adverse childhood experiences (ACEs) on maternal functioning, especially among low-income Black mothers. Using self-report data from a subsample of Black mothers (N = 157) who participated in a larger study to evaluate the effectiveness of an urban public prekindergarten program in the mid-Atlantic region of the United States, we examined the prevalence of ACEs and the individual and cumulative effects of conventional (i.e., family trauma and dysfunction) and expanded (i.e., community stressors) ACEs on depression and health among low-income Black mothers. Findings indicated that Black mothers had more exposure to expanded than conventional ACEs. Hierarchical regression analyses revealed that experience of physical neglect was significantly associated with depression and physical abuse with compromised health, and perceived experience of racism was a predictor of depression and compromised health. More conventional and expanded ACEs were associated with clinical levels of depression and compromised health. Findings highlight the need for more research related to the impact of ACEs, especially expanded ACEs, on mental and behavioural health outcomes. Additionally, our findings indicate the need for more trauma-informed care to reduce and address the impact of individual and community-level adversities on low-income Black mothers.  相似文献   
105.
This article presents a historical reprise of 40 years of policy interest in ethnic minority businesses in the UK. It contrasts the pronouncements of policymakers with the reality of ethnic minority entrepreneurship. Such an exercise is surprisingly rare given the activism of policymakers in this arena and growing scholarly interest in this field. Our historical overview is informed by a novel research method that plots references to ethnic minority entrepreneurship in the British Houses of Parliament. Though the UK has been the site of some interesting policy experiments on ethnic minority entrepreneurship, their impact has been slight when set against the context of broader political-economic change.  相似文献   
106.
One significant change in adoption practice that has occurred over the last four decades is the shift away from an expectation of confidentiality towards an expectation of openness in adoption. Openness is typically conceived in terms of the level of contact between adoptive and birth families following adoption or the extent to which adoption is openly discussed within the adoptive family. While these shifts in practice have generated controversy, they are largely supported by research evidence and have become a feature of contemporary adoptive family life. As a result, the narrative that has emerged in relation to openness in adoption is one of historical progress. In this paper, I argue that the lived reality of adoption is less straightforward than this narrative suggests. An analysis of the social and cultural context in which adoption operates suggests instead that the persistent feature of adoption throughout this historical period of increasing openness can be more accurately described as a state of enduring ambiguity regarding the nature of post‐adoption relationships. The paper highlights the potentially damaging consequences of overlooking this aspect of adoptive family life and comments on the role of policy in shaping openness in adoption.  相似文献   
107.
108.
The Narrative Policy Framework has a growing number of researchers seeking to apply the framework in policy process scholarship. This article is intended to assist those interested in conducting an NPF study that is ‘clear enough to be wrong’ (Sabatier, 2000). While graduate programs offer critical methodological training, this article focuses on the specific application of the NPF to research inquiries about the role of policy narratives in the policy process. We approach our discussion by examining various decisions in the research process and include a detailed discussion of specifying the model and obtaining narrative data. We also point out areas for further investigation.  相似文献   
109.
How peer groups contribute to educational outcomes has long interested researchers. However, the possibility that peer groups dominated by either low- or high-achieving youth can have substantively different effects on achievement has been largely ignored. In this paper, we show that while being embedded in a high-achieving network of friends is not associated with increased own achievement, being embedded in a low-achieving network is associated with decreased own achievement. In additional analyses, we present evidence that these associations are at least in part due to influence, as opposed to only selection effects or shared environment. We also examine whether the structure of the network in which a student is embedded might affect their educational achievement. We show that achieving at higher levels positively predicts how centrally located a student is in their network, but being more centrally located does not predict concurrent achievement. This finding suggests that the behavior of individuals is affecting the formation of network structure and not the reverse.  相似文献   
110.
Ethical dimensions of friendship have rarely been explicitly addressed as aspects of friendship quality in studies of children's peer relationships. This study identifies aspects of moral virtue significant for friendship, as a basis for empirically investigating the role of ethical qualities in children's friendship assessments and aspirations. We introduce a eudaimonic conception of friendship quality, identify aspects of moral virtue foundational to such quality, review and contest some grounds on which children have been regarded as not mature enough to have friendships that require virtue, and report a qualitative study of the friendship assessments and aspirations of children aged nine and ten (n = 83). In focus group sessions conducted in ten schools across Great Britain, moral qualities figured prominently in children's assessments of friendship quality. The findings provide evidence of children having friendships exhibiting mutual respect, support, and valuing of each other's good character.  相似文献   
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