ESTIMATING LANDSCAPE-SCALE SPECIES RICHNESS: RECONCILING FREQUENCY- AND TURNOVER-BASED APPROACHES

One hypothesis for why estimators of species richness tend to underestimate total richness is that they do not explicitly account for increases in species richness due to spatial or environmental turnover in species composition (beta diversity). I analyze the similarity of a data set of native trees in Great Smoky Mountains National Park, USA, and assess the robustness of these estimators against recently developed ones that incorporate turnover explicitly: the total species accumulation method (T-S) and a method based on the distance decay of similarity. I show that the T-S estimator can give reliable estimates of species richness, given an appropriate grouping of sites. The estimator based on distance decay of similarity performed poorly. There are two main reasons for this: sample size effects and the assumption that distance decay of similarity exhibits a power law relationship. I show that estimators based on distance-decay relationships exhibit systematically lower rates of distance decay for samples with few individuals per site independent of environmental variation. Second, the data presented here and many other survey data sets exhibit exponential rather than power law distance-decay relationships. Richness estimators that explicitly incorporate beta diversity can be improved by beginning from an exponential distance-decay relationship and adjusting for the systematic errors introduced by small sample sizes

Perspectives on gender in eating disorders

This thesis examines perspectives on gender in eating disorders. Chapter one critically reviews research into psychosocial influences on adolescent boys' concerns about eating and body shape. [...] Chapter two is an empirical study of therapists' experiences of working with men with eating disorders. [...] Chapter three provides a reflective account of the author's experiences of being a Trainee Clinical Psychologist working with female patients in an eating disorder service

Patterns of Change in Children’s Loneliness: Trajectories from Third Through Fifth Grades

Latent growth-mixture modeling was used to investigate patterns of change in loneliness for 170 children from third through fifth grades. A three-class model representing unique trajectories of loneliness provided the best overall fit to the data, including a Stable Low group (65%), as well as groups of Increasers (23%) and Decreasers (12%). Groups were then compared on aspects of peer functioning, including peer optimism, classroom sociometric ratings, and peer behavior nominations that were also collected in third, fourth, and fifth grades. The Stable Low group was characterized by positive peer functioning (elevated peer optimism, below-average victimization and passive social withdrawal nominations, and above-average mutual friendships). The Increasers had elevated passive social withdrawal and later victimization nominations, and possibly represent a subgroup of children at risk for developing later internalizing symptomatology. The Decreasers had a less clear pattern of peer functioning in third grade but were indistinguishable from the Stable Low group by fourth and fifth grades. Findings are discussed in the context of the development of loneliness in middle childhood

Biodiversity and Scale: Determinants of Species Richness in Great Smoky Mountains National Park

Species richness is the number of species in a given area or sample and is the most fundamental measure of biodiversity. It results from the aggregation of individual species whose distributions are influenced by processes operating on a wide range of scales. Estimating and understanding species richness at landscape scales (103-106 ha) is not easily achieved from small sample areas that can be completely inventoried. In particular the spatial structure of environments makes the richness observations across a landscape non-additive. This dissertation develops the vital links between the spatial structure of ecological factors that are hypothesized to control species richness, spatial variation in species composition, and the sampling strategies used to measure species richness. I present a method for objectively and iteratively assessing patterns of biodiversity. This method builds upon "ecological zipcodes" that classify the landscape by energy flux, temperature, and precipitation. I also present a model of human energetic expenditure during walking that can be applied at landscape scales. I use this model to analyze sampling bias associated with accessibility for vegetation surveys. I used both the "ecological zipcodes" and the model of accessibility to design efficient and representative biodiversity samples based on clustered-stratified sampling. Finally, I assess the reliability of richness estimators that incorporate turnover in species composition. My results illustrate that efficient and representative richness assessment is possible, even with little a priori knowledge about the spatial structure of species richness. They also demonstrate that typical biodiversity assessments show a strong bias in accessibility that is both a product of the spatial structuring of samples as well as environment. This bias is significant even for small biases in sample accessibility. Also, I show that though clustered sampling designs capture multiple scales of aggregation, their representativeness is very sensitive to stratification. Finally, my results show that species richness estimates that incorporate turnover are confounded by the interaction between sample size and environmental heterogeneity. Only when controlling for these effects, can information about the spatial turnover in species composition be effective in estimating species richness

LOFT Debriefings: An Analysis of Instructor Techniques and Crew Participation

This study analyzes techniques instructors use to facilitate crew analysis and evaluation of their Line-Oriented Flight Training (LOFT) performance. A rating instrument called the Debriefing Assessment Battery (DAB) was developed which enables raters to reliably assess instructor facilitation techniques and characterize crew participation. Thirty-six debriefing sessions conducted at five U.S. airlines were analyzed to determine the nature of instructor facilitation and crew participation. Ratings obtained using the DAB corresponded closely with descriptive measures of instructor and crew performance. The data provide empirical evidence that facilitation can be an effective tool for increasing the depth of crew participation and self-analysis of CRM performance. Instructor facilitation skill varied dramatically, suggesting a need for more concrete hands-on training in facilitation techniques. Crews were responsive but fell short of actively leading their own debriefings. Ways to improve debriefing effectiveness are suggested

Facilitating LOS Debriefings: A Training Manual

This manual is a practical guide to help airline instructors effectively facilitate debriefings of Line Oriented Simulations (LOS). It is based on a recently completed study of Line Oriented Flight Training (LOFT) debriefings at several U.S. airlines. This manual presents specific facilitation tools instructors can use to achieve debriefing objectives. The approach of the manual is to be flexible so it can be tailored to the individual needs of each airline. Part One clarifies the purpose and objectives of facilitation in the LOS setting. Part Two provides recommendations for clarifying roles and expectations and presents a model for organizing discussion. Part Tree suggests techniques for eliciting active crew participation and in-depth analysis and evaluation. Finally, in Part Four, these techniques are organized according to the facilitation model. Examples of how to effectively use the techniques are provided throughout, including strategies to try when the debriefing objectives are not being fully achieved

Performance Data Errors in Air Carrier Operations: Causes and Countermeasures

Several airline accidents have occurred in recent years as the result of erroneous weight or performance data used to calculate V-speeds, flap/trim settings, required runway lengths, and/or required climb gradients. In this report we consider 4 recent studies of performance data error, report our own study of ASRS-reported incidents, and provide countermeasures that can reduce vulnerability to accidents caused by performance data errors. Performance data are generated through a lengthy process involving several employee groups and computer and/or paper-based systems. Although much of the airline indUStry 's concern has focused on errors pilots make in entering FMS data, we determined that errors occur at every stage of the process and that errors by ground personnel are probably at least as frequent and certainly as consequential as errors by pilots. Most of the errors we examined could in principle have been trapped by effective use of existing procedures or technology; however, the fact that they were not trapped anywhere indicates the need for better countermeasures. Existing procedures are often inadequately designed to mesh with the ways humans process information. Because procedures often do not take into account the ways in which information flows in actual flight ops and time pressures and interruptions experienced by pilots and ground personnel, vulnerability to error is greater. Some aspects of NextGen operations may exacerbate this vulnerability. We identify measures to reduce the number of errors and to help catch the errors that occur