Spatial distribution of structure infesting ant species inhabiting urban housing developments of different ages

The distribution of ant colonies within a community is often well defined, yet this distribution can change due to changing environmental conditions, resource availability, and colony growth. In this study, structure infesting ant communities were sampled for one year within three Puerto Rican housing developments of different ages. These developments represented environments in different stages of recovery after a disturbance (secondary succession). Spatial mapping was used to plot the distribution and abundance of ant communities within these developments. At the beginning of the study, the youngest housing development (1 year since construction), had the fewest number of species present (ave. 1.6 per house). The second housing development (4 years old) had a greater number of species (ave. 2.6 per house), and a greater sampling frequency (the same species collected at multiple houses) than Site 1. The oldest development (8 years old) had both the greatest number of species (ave. 2.7 per house), and sampling frequency of the three sites. In all developments, the number of species, sampling frequency, and ant biomass increased throughout the year as colonies grew and foraging ranges expanded. It was observed in all developments, that species coexistence also increased throughout the year. As colony populations increased, there was a greater occurrence of multiple species being collected at the same sample house. In the youngest development, the two most dominant species increased in numbers during the year and began to be collected from the same sample houses. Spatial diagrams documented that multiple species in the older housing developments (later stages of succession), also shared a common distribution. Even the most dominant species (S. invicta) in all three sites, did not exclude additional species from foraging within its established range.     

The mean of linear signed rank statistics under alternatives

An expression is presented for the mean of a linear signed rank statistic for the one sample location model. Several examples are given to illustrate its application.     

Implementing a Multidimensional Poverty Measure Using Mixed Methods and a Participatory Framework

Recently, there have been advances in the development of multidimensional poverty measures. Work is needed however on how to implement such measures. This paper deals with the process of selecting dimensions and setting weights in multidimensional poverty measurement using qualitative and quantitative methods in a participatory framework. We estimate the multidimensional poverty measures developed by Alkire and Foster for a particular group: persons with psychiatric diagnoses in the United States. To select relevant dimensions and their relative ordering, two discussion groups are convened: one consisting of persons with lived-experience expertise and the other consisting of people with mental health service provision or research expertise. Several methods are used to convert dimension rankings into weights. The selection and ordering of dimensions differed between the two discussion groups, as did the resulting poverty measures. For instance, the poverty headcount using the dimensions and weights of the ‘lived experience’ group ranged from 20.61 to 26.96% as compared to a range of 18.62–33.19% using those of the ‘provider/researcher’ group. One of the main results of this study is that the Alkire Foster method is sensitive to the selection of dimensions and the methods used to derive rankings and weights. It points toward the limitation of relying exclusively on small scale qualitative methods for the selection and ranking of dimensions. In addition, the participatory framework used in this study was found to be essential in interpreting results, in particular with respect to the limitations of the data set in measuring relevant dimensions.     

Palliative and curative care nurses' attitudes toward dying and death in the hospital setting

This paper explores the errors involved in the approximation of both the maximum and sum of two independent Beta random variables, each by another Beta random variable. The principal area of application is the time analysis of PERT networks, and the results are interpreted and discussed in terms of this application. The error was found to be acceptable for the greater part of the range of the parameters involved. The results will help practitioners estimate the mean and standard deviation of the completion time of PERT networks.     

Biologically Motivated Cancer Risk Models

A two-stage dose response model is proposed for use in cancer risk assessment. The model assumes that transformation probabilities and cellular dynamics are exposure- and time-dependent.     

Research Notes on the Best British Companies: a Peer Evaluation of Britain's Leading Firms

The assessment of company performance is one of the major dilemmas facing the strategic researcher. This paper reviews the alternative methods available, then uses one approach, peer assessment, to produce a guide to British company performance. Britain's best companies are identified and their profiles are examined. Their declared financial strengths and relative weaknesses in marketing and innovation are identified.     

Assessing Engineering Resilience for Systems with Multiple Performance Measures

Recently, efforts to model and assess a system's resilience to disruptions due to environmental and adversarial threats have increased substantially. Researchers have investigated resilience in many disciplines, including sociology, psychology, computer networks, and engineering systems, to name a few. When assessing engineering system resilience, the resilience assessment typically considers a single performance measure, a disruption, a loss of performance, the time required to recover, or a combination of these elements. We define and use a resilient engineered system definition that separates system resilience into platform and mission resilience. Most complex systems have multiple performance measures; this research proposes using multiple objective decision analysis to assess system resilience for systems with multiple performance measures using two distinct methods. The first method quantifies platform resilience and includes resilience and other “ilities” directly in the value hierarchy, while the second method quantifies mission resilience and uses the “ilities” in the calculation of the expected mission performance for every performance measure in the value hierarchy. We illustrate the mission resilience method using a transportation systems‐of‐systems network with varying levels of resilience due to the level of connectivity and autonomy of the vehicles and platform resilience by using a notional military example. Our analysis found that it is necessary to quantify performance in context with specific mission(s) and scenario(s) under specific threat(s) and then use modeling and simulation to help determine the resilience of a system for a given set of conditions. The example demonstrates how incorporating system mission resilience can improve performance for some performance measures while negatively affecting others.     

A methodological strategy for a one-number census in the UK

As a result of lessons learnt from the 1991 census, a research programme was set up to seek improvements in census methodology. Underenumeration has been placed top of the agenda in this programme, and every effort is being made to achieve as high a coverage as possible in the 2001 census. In recognition, however, that 100% coverage will never be achieved, the one-number census (ONC) project was established to measure the degree of underenumeration in the 2001 census and, if possible, to adjust fully the outputs from the census for that undercount. A key component of this adjustment process is a census coverage survey (CCS). This paper presents an overview of the ONC project, focusing on the design and analysis methodology for the CCS. It also presents results that allow the reader to evaluate the robustness of this methodology.