Intrinsic and extrinsic drivers of yard vegetation in urban residential areas: implications for conservation planning

Residential green areas often represent a significant portion of a city’s green infrastructure which has generated great interest in studying the factors that contribute to the formation of plant associations in residential yards. This project evaluated the external factors to the household social-ecological system that influence the availability of plants for residential landscapes and how they may influence the presence of native plants in residential yards on households within the Río Piedras watershed in the metropolitan area of San Juan, Puerto Rico. The methods used included a residential survey with open and closed questions that addressed the sources of plants used in landscaping and an evaluation of ornamental plant species inventories from local nurseries. A total of 432 yards were surveyed. Yard plants in this watershed have multiple sources. Aside from obtaining plants at local nurseries, natural dispersion, exchanges among family and friends and historical plantings can be just as important sources of yard plants. Our results also suggest that the majority of residents do not know where to get native plants which could represent a challenge for the development and implementation of initiatives for natives gardening. At the same time, most commercial nurseries have a deficit of native plants in their inventories. This information is critical to species conservation strategies that seek the inclusion of urban residential areas and may help improve initiatives about the involvement of individual citizens in sustainable gardening practices at the residential scale.     

HOW DO VOLUNTARY ORGANIZATIONS FOSTER PROTEST? THE ROLE OF ORGANIZATIONAL INVOLVEMENT ON INDIVIDUAL PROTEST PARTICIPATION

Prior research shows that members of voluntary organizations are more likely to protest than nonmembers. But why, among members, do some protest while others do not? I explore whether organizational involvement—the extent in which members engage in the “life” of their organizations—affects protest. I identify four dimensions of involvement—time and money contributions, participation in activities, psychological attachment, and embeddedness in interpersonal communication networks. Only the first dimension has robust effects on protest, and they are nonlinear: intermediate contributors have the highest protest rates. The three other dimensions substantially increase protest only under specific “involvement profiles.”     

Delayed treatment effects,treatment switching and heterogeneous patient populations: How to design and analyze RCTs in oncology

In the analysis of survival times, the logrank test and the Cox model have been established as key tools, which do not require specific distributional assumptions. Under the assumption of proportional hazards, they are efficient and their results can be interpreted unambiguously. However, delayed treatment effects, disease progression, treatment switchers or the presence of subgroups with differential treatment effects may challenge the assumption of proportional hazards. In practice, weighted logrank tests emphasizing either early, intermediate or late event times via an appropriate weighting function may be used to accommodate for an expected pattern of non-proportionality. We model these sources of non-proportional hazards via a mixture of survival functions with piecewise constant hazard. The model is then applied to study the power of unweighted and weighted log-rank tests, as well as maximum tests allowing different time dependent weights. Simulation results suggest a robust performance of maximum tests across different scenarios, with little loss in power compared to the most powerful among the considered weighting schemes and huge power gain compared to unfavorable weights. The actual sources of non-proportional hazards are not obvious from resulting populationwise survival functions, highlighting the importance of detailed simulations in the planning phase of a trial when assuming non-proportional hazards.We provide the required tools in a software package, allowing to model data generating processes under complex non-proportional hazard scenarios, to simulate data from these models and to perform the weighted logrank tests.     

The influence of aircraft size on airline operating costs

Many previous studies have shown that there are probably no economies of scale in the airline industry directly attributable to firm size. Scale effects within the firm, however, have often been suggested, particularly for example with regard to such firm-size independent factors as market density, route length, or aircraft size. The focus of this paper is the effect of aircraft size on an airline's unit cost. Though much of the previous evidence appears to be at variance with a priori expectations, the empirical results presented here suggest that most of the divergence is probably due to a conceptually inadequate basis of comparison. Appropriately compared, actual unit costs were generally found to decrease at a decreasing rate with aircraft size, though as the route length parameter is reduced some mild diseconomies appeared. Of further interest, the behavior with size of the underlying cost components was found to be quite diverse, the (far from uniform) decreases with size in unit crew, fuel, and maintenance costs being offset somewhat by increases in unit capital costs, insurance plus other costs, and landing fees.     

Communicating the Risks of a New, Emerging Pathogen: The Case of Cryptococcus gattii

The news media are an important channel for communicating public health messages, providing important information about geographic extent, symptoms, and precautionary measures. This function may be particularly important in the case of new and emerging infectious diseases, which are unfamiliar to both the public and health professionals. We conducted a content analysis of the coverage in six Canadian newspapers of two ¨emerging infectious pathogens in British Columbia (BC), West Nile virus and Cryptococcus gattii ( C. gattii ), between 2001 and 2006. C. gattii was first identified in the Canadian Pacific Northwest in 1999, having previously been restricted to tropical and subtropical areas. By summer 2006, C. gattii had killed at least eight people and was responsible for over 150 hospitalizations in the province of BC, as well as significant morbidity and mortality among companion animals. West Nile virus reached Canada in 2001 and has since caused significant morbidity and mortality. It has not, to date, reached BC. Despite the much higher incidence of disease and death caused by C. gattii in BC, West Nile virus received five times more news coverage in the British Columbian and national newspapers examined. Surprisingly, the local newspaper closest to the center of the British Columbia C. gattii outbreak had a much lower proportion of coverage of the disease than other papers in the province. The article discusses possible explanations for these findings, and the implications for public health communication.     

The road to conventional tool use: Developmental changes in children's material engagement with artifacts in nursery school

The development of tool use in early childhood is a topic of continuing interest in developmental psychology. However, the lack of studies in ecological settings results in many unknowns about how children come to use artifacts according to their cultural function. We report a longitudinal study with 17 sociodemographically diverse children (8 female) attending a nursery school in Madrid (Spain) and their two adult female teachers. Using mixed-effects models and Granger causality analysis, we measured changes in the frequency and duration of children's object uses between 7 and 17 months of age and in the directional influences among pairs of behaviors performed by teachers and children. Results show a clear shift in how children use artifacts. As early as 12 months of age, the frequency of conventional uses outweighs that of all other types of object use. In addition, object uses become shorter in duration with age, irrespective of their type. Moreover, certain teachers' nonlinguistic communicative strategies (e.g., demonstrations of canonical use and placing gestures) significantly influence and promote children's conventional tool use. Findings shed light on how children become increasingly proficient in conventional tool use through interactions with artifacts and others in nursery school.