Inference on high-dimensional implicit dynamic models using a guided intermediate resampling filter

Statistics and Computing - We propose a method for inference on moderately high-dimensional, nonlinear, non-Gaussian, partially observed Markov process models for which the transition density is...     

Lay Understanding of Synergistic Risk: The Case of Radon and Cigarette Smoking

The combination of radon and smoking produces a synergistic risk of lung cancer. Lay understanding of this risk was examined from the perspectives of mental models theory, the psychometric approach to risk perception, and optimistic bias. As assessed by interview, participants ( N = 50) had more extensive mental models for the risks of smoking than for the risks of radon or the combination of radon and smoking; 32% knew little or nothing about radon. Despite reading an informational brochure, their risk-perception ratings of the three hazards showed no perception of the synergy between smoking and radon risk, although the combined hazard was rated as less familiar but more controllable than the average of the single hazards ( p < .01). No evidence of optimistic bias for the health consequences of radon, or the combination of radon and smoking was observed. Participants appeared to be combining the single-hazard risks subadditively to arrive at their combined-hazard risk perceptions. Further research on the integration of perceived risks would be beneficial for designing optimal communications about synergistic risk.     

The Timing of Capacity Investment with Lead Times: When Do Firms Act in Unison?

We study competitive capacity investment for the emergence of a new market. Firms may invest either in capacity leading demand or in capacity lagging demand at different costs. We show how the lead time and other operational factors including volume flexibility, existing capacity, and demand uncertainty impact equilibrium outcomes. Our results indicate that a type of bandwagon behavior is the most likely equilibrium outcome: if both firms are going to invest, then they are most likely to act in unison. Contrary to much received wisdom, we show that leader–follower behavior is very uncommon in equilibrium where firms do not have volume flexibility, and will not occur at all if lead times are sufficiently short. On the other hand, if there is volume flexibility in production, then the likelihood of this sequential investment behavior increases. Our findings underscore the importance of operational characteristics in determining the competitive dynamics of capacity investment timing.     

Validation and Application of Models to Predict Facemask Influenza Contamination in Healthcare Settings

Facemasks are part of the hierarchy of interventions used to reduce the transmission of respiratory pathogens by providing a barrier. Two types of facemasks used by healthcare workers are N95 filtering facepiece respirators (FFRs) and surgical masks (SMs). These can become contaminated with respiratory pathogens during use, thus serving as potential sources for transmission. However, because of the lack of field studies, the hazard associated with pathogen‐exposed facemasks is unknown. A mathematical model was used to calculate the potential influenza contamination of facemasks from aerosol sources in various exposure scenarios. The aerosol model was validated with data from previous laboratory studies using facemasks mounted on headforms in a simulated healthcare room. The model was then used to estimate facemask contamination levels in three scenarios generated with input parameters from the literature. A second model estimated facemask contamination from a cough. It was determined that contamination levels from a single cough (≈19 viruses) were much less than likely levels from aerosols (4,473 viruses on FFRs and 3,476 viruses on SMs). For aerosol contamination, a range of input values from the literature resulted in wide variation in estimated facemask contamination levels (13–202,549 viruses), depending on the values selected. Overall, these models and estimates for facemask contamination levels can be used to inform infection control practice and research related to the development of better facemasks, to characterize airborne contamination levels, and to assist in assessment of risk from reaerosolization and fomite transfer because of handling and reuse of contaminated facemasks.     

Developing the e-learning community

This paper considers aspects of the theory and practice of e-learning communities. To date much of the research and discussion in this area has been drawn from experiences in education where the prevalent model is best described as supported on-line learning. Propositions on the structure of the e-learning community, and on the role of the moderator, have been based largely on lessons drawn from practice in higher education. The growing importance of e-learning as a tool for informal learning and team development in business is leading to new types of e-learning communities with different objectives, different boundaries and membership, different demands on the moderator and different measures of effectiveness. Two e-learning communities are outlined and some key characteristics are presented.     

Factors Associated with Advance Care Planning Among Older Women in Southwest Florida

ABSTRACT

As the nation's population continues to age, many older women will face care needs that can be anticipated in advance. However, little is known about the advance care plans of older women and the characteristics of those who plan. This study utilized a stratified random sampling design to survey older women (n = 124) in the state of Florida regarding their attitudes toward future care and planning behavior in social-environmental, health, and financial domains. Regression analyses were conducted to determine factors most predictive of attitudes toward future care and planning behavior by domain. Results suggest that advanced age predicts greater planning behavior, while living alone is associated with less advance care planning behavior. Other factors associated with less planning by domains of care needs include income status, chronic health conditions, educational attainment, and religious status. Nonaccepting attitudes toward planning were associated with a decreased likelihood to have advance care planning documents.     

Exchange and cohesion in dyads and triads: A test of Simmel’s hypothesis

This paper uses social exchange theory to address a classic question posed by Simmel (1964) regarding dyads and triads. The question is whether exchanges in a triad will generate more cohesion at the group level than exchanges in an isolated dyad. The main hypotheses, integrating several ideas from Simmel and social exchange theories, are as follows. First, triads generate less variability of behavior than dyads; that is, there is more uniformity or convergence in triads. Second, in the context of repeated exchange, we predict higher levels of cohesion in triads than in dyads. Third, positive emotion or affect has a stronger impact on cohesion in dyads than in triads, whereas uncertainty reduction has a stronger impact on cohesion in triads. To test these hypotheses, an experiment compared isolated dyads to dyads nested in a triadic exchange network. Subjects engaged in exchanges across a series of distinct episodes, using standard experimental procedures from research on relational cohesion (Lawler and Yoon, 1996) and exchange networks (Molm and Cook, 1995, Willer, 1999). Consistent with the hypotheses, the results reveal more convergence of behavior and higher cohesion in triads than in dyads; moreover, uncertainty reduction is the primary basis for cohesion in the triad, whereas positive affect was the primary basis for cohesion in the dyad. These results are discussed in relation to Simmelian dyad–triad dynamics and the theory of relational cohesion.     

ABOUT THE AUTHORS

Work satisfaction, self‐esteem, and alienation measures were obtained from white males in three service occupations (bartenders, barbers, and mailmen) at different levels of the occupational prestige hierarchy. While we found an overall positive relationship between work satisfaction and occupational prestige, this only held for variables where societal reference groups were forced upon the respondents. Such findings suggest that the relationship between work satisfaction and occupational prestige is less absolute than usually suggested by the literature. Hypotheses from the literature arguing for a direct relationship between occupational prestige and alienation were not supported by our data. We conclude that sociologists probably overestimate the salience of work and occupational prestige for the working class.     

Institutional obstacles to service delivery in South Africa

This paper argues that the service‐delivery crisis facing two‐thirds of the municipalities across South Africa is caused by a series of institutional shortcomings ranging from incoherence in national policy towards rural and urban development, a lack of enforcement when it comes to financial controls and competencies, and a lack of skills affecting local officials ranging from customer service and relations, to financial controls, to technical competencies in the core areas of electrification, basic water and sanitation, and refuse collection. Government needs to address the skills shortage at the local level and enforce the rules and regulations concerning the role of public and elected officials to ensure not only service delivery but accountability and transparent decision‐making. Attending to the skills shortage and enforcing relevant rules would ensure better service delivery and, in turn, encourage bringing ‘democracy to the people’, which is at the heart of the post apartheid government’s decentralisation project.