Small‐sphere distributions for directional data with application to medical imaging

We propose novel parametric concentric multi‐unimodal small‐subsphere families of densities for p ? 1 ≥ 2‐dimensional spherical data. Their parameters describe a common axis for K small hypersubspheres, an array of K directional modes, one mode for each subsphere, and K pairs of concentrations parameters, each pair governing horizontal (within the subsphere) and vertical (orthogonal to the subsphere) concentrations. We introduce two kinds of distributions. In its one‐subsphere version, the first kind coincides with a special case of the Fisher–Bingham distribution, and the second kind is a novel adaption that models independent horizontal and vertical variations. In its multisubsphere version, the second kind allows for a correlation of horizontal variation over different subspheres. In medical imaging, the situation of p ? 1 = 2 occurs precisely in modeling the variation of a skeletally represented organ shape due to rotation, twisting, and bending. For both kinds, we provide new computationally feasible algorithms for simulation and estimation and propose several tests. To the best knowledge of the authors, our proposed models are the first to treat the variation of directional data along several concentric small hypersubspheres, concentrated near modes on each subsphere, let alone horizontal dependence. Using several simulations, we show that our methods are more powerful than a recent nonparametric method and ad hoc methods. Using data from medical imaging, we demonstrate the advantage of our method and infer on the dominating axis of rotation of the human knee joint at different walking phases.     

Key Determinants to using Telehealth Technology to Serve Medically Ill and Depressed Homebound Older Adults

Despite the increasing evidence for the effectiveness of telehealth technology in screening and treating chronic diseases, and comorbid depression among older adults, they have been slowly adopted by home health care (HHC) agencies. Therefore, this study aimed to identify factors that determine telehealth technology adoption. Twenty directors from the National Association for Homecare & Hospice member agencies completed a 45-min telephone interview. Questions were asked regarding their perceptions of telehealth, the key determinants of telehealth adoption and use, and recommendations they would give on telehealth adoption. The majority of the participants perceived telehealth as effective for managing symptoms and reducing cost. Meanwhile, some participants had a mixed feeling toward telehealth for depression care as they did not recognize their agency as equipped with the necessary resources and trained staff. Moreover, significant determinants of telehealth adoption included the agency-related characteristics, the patient-home environment, reimbursement and cost-related factors, and staff telehealth perception. Findings imply that there is a need for financial support both at the state and the federal levels to encourage telehealth adoption among HHC agencies. Future studies should consider exploring strategies used by successful programs to overcome barriers.     

The Role of Internal and External Complexity in Global Factory Performance: An NKC Application

The global factory literature suggests that MNCs can take advantage of global operations by extensively offshoring and outsourcing activities. However, the added difficulty for the lead firm to coordinate the resulting complex structure is often underestimated. Evidence could be found in Boeing's 787 Dreamliner project, in which the external complexity disrupted MNC performance. Motivated by the gap between theory and practice, this study focuses on systems of MNCs connected with each other with supplier-client relationships and/or outsourcing. In particular it investigates the interplay of the internal and external complexity in such systems and how their balance affects the system performance. The study models the internal and external complexity by using the NKC-simulation methodology and adjusting it to the specific MNC context. The NKC methodology is widely used in organization theory to study complex systems. Simulations comparing the performance of MNCs that use outsourcing to different degrees indicate that a balanced level of internal and external complexity is beneficial in the context of global factory.     

Marriage Migration Policy in South Korea: Social Investment beyond the Nation State

This article seeks to contribute to understandings of South Korea's approach to marriage migration. Situating our analysis of marriage migration policy specifically within the recent emergence of a social investment approach to welfare, we bring together two bodies of literature that due to the methodological nationalism of much welfare state scholarship are usually treated separately. Through an examination of the policy framework governing marriage migration ‐ so‐called ‘multicultural family policies’ ‐ we find that successive Korean governments have actively sought female marriage migrants to perform various social reproductive roles as a means to secure the reproductive capacity of the nation, just as feminist scholars have argued the care work of citizen‐mothers can be understood. Our analysis also suggests that marriage migration policy in Korea constitutes a distinctly transnational dimension to its overall social investment approach, which is strongly motivated by concerns to reproduce the next generation of human capital.     

Building relational capital: The contribution of episodic and relational community engagement

In this study, we provide evidence of the theorized connection between community engagement and the development of social capital, and the perceived value or worth of relationships among organizations and stakeholders. Using thematic analysis to understand the policy and practice frameworks of community engagement in Australian local government organizations, our analyses reveal two different types of community engagement—relational and episodic—each of which has the potential to contribute to relational dimension of social capital. The study introduces and develops new thinking around the ideas of episodic and relational engagement within the context of community engagement, and their respective contributions to the development of relational capital. Recognizing and identifying episodic and relational community engagement as separate phenomena allows researchers and practitioners to understand the theoretical dimensions of community engagement as a framework for practice.     

Bayesian partial likelihood approach for tied observations

The Bayesian analysis based on the partial likelihood for Cox's proportional hazards model is frequently used because of its simplicity. The Bayesian partial likelihood approach is often justified by showing that it approximates the full Bayesian posterior of the regression coefficients with a diffuse prior on the baseline hazard function. This, however, may not be appropriate when ties exist among uncensored observations. In that case, the full Bayesian and Bayesian partial likelihood posteriors can be much different. In this paper, we propose a new Bayesian partial likelihood approach for many tied observations and justify its use.     

A longitudinal analysis of the impact of health shocks on the wealth of elders

We investigate the impact of health shocks on wealth, using all four waves of the Health and Retirement Study, and estimate not only the short-term effect but also the long-term effect of health shocks on wealth of the elderly. We find that new health events lower wealth in elders during the period in which such health shocks occur, but the impact tends to disappear over time. We also find that health shocks result in greater wealth depletion when they occur later in life. Together with existing health problems, the overall impact of health problems on wealth increases over time.

Life with and without heart disease among women and men over 50

This article uses a demographic approach and data from the Health and Retirement Survey, a nationally representative sample of the U.S. population, to investigate sex differences in the length of life lived with heart disease and after a heart attack for persons in the United States age 50 and older. On average, women live longer than men with heart disease. At age 50 women can expect to live 7.9 years and men 6.7 years with heart disease. The average woman experiences heart disease onset three years older and heart attacks 4.4 years older than men.     

The making and unmaking of a “transborder nation”: South Korea during and after the Cold War

The burgeoning literature on transborder membership, largely focused on the thickening relationship between emigration states in the South and the postwar labor migrant populations and their descendants in North America or Western Europe, has not paid due attention to the long-term macroregional transformations that shape transborder national membership politics or to the bureaucratic practices of the state that undergird transborder claims-making. By comparing contentious transborder national membership politics in South Korea during the Cold War and Post-Cold War eras, this article seeks to overcome these limitations. In both periods, the membership status of colonial-era ethnic Korean migrants in Japan and northeast China and their descendants was the focus of contestation. The distinctiveness of the case—involving both a sustained period of colonial rule and a period of belated and divided nation-state building interwoven with the Cold War—highlights the crucial importance of three factors: (1) the dynamically evolving macro-regional context, which has shaped transborder national membership politics in the region in distinctive ways; (2) the essentially political, performative, and constitutive nature of transborder nation-building; and (3) the role of state registration and documentation practices in shaping the contours of transborder national membership politics in the long run. By incorporating Korea—and East Asia more broadly—into the comparative study of transborder nation-building, this article also lays the groundwork for future cross-regional comparative historical studies.

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