A quantitative approach to improving the analysis of faecal worm egg count data

Analysis of Faecal Egg Count (FEC) and Faecal Egg Count Reduction Test (FECRT) datasets is frequently complicated by a high degree of variability between observations and relatively small sample sizes. In this thesis, statistical issues pertaining to the analysis of FEC and FECRT data are examined, and improved methods of analysis using Bayesian Markov chain Monte Carlo (MCMC) are developed. Simulated data were used to compare the accuracy of MCMC methods to existing maximum likelihood methods. The potential consequences of model selection based on empirical fit were also examined by comparing inference made from simulated data using different distributional assumptions. The novel methods were then applied to FEC data obtained from sheep and horses. Several syntactic variations of FECRT models were also developed, incorporating various different distributional assumptions including meta-population models. The inference made from simulated data and FECRT data taken from horses was compared to that made using the currently most widely used methods. Multi-level hierarchical models were then used to partition the source of the observed variability in FEC using data intensively sampled from a small group of horses. The MCMC methods out-performed other methods for analysis of simulated FEC and FECRT datasets, particularly in terms of the usefulness of 95% confidence intervals produced. There was no consistent difference in model fit to the gamma-Poisson or lognormal-Poison distributions from the available data. However there was evidence for the existence of bi-modality in the datasets. Although the majority of the observed variation in equine FEC is likely a consequence of variability between animals, a considerable proportion of the variability is due to the variability in true FEC between faecal piles and the aggregation of eggs on a local scale within faeces. The methods currently used for analysis of FEC and FECRT data perform poorly compared to MCMC methods, and produce 95% confidence intervals which are unreliable for datasets likely to be encountered in clinical parasitology. MCMC analysis is therefore to be preferred for these types of data, and also allows multiple samples taken from each animal to be incorporated into the analysis. Analysing the statistical processes underlying FEC data also revealed simple methods of reducing the observed variability, such as increasing the size of individual samples of faeces. Modelling the variability structure of FEC data, and use of the inferred parameter values in precision analysis and power analysis calculations, allows the usefulness of a study to be quantified before the data are collected. Given the difficulties with analysing FEC and FECRT data demonstrated, it is essential that such consideration of the statistical issues pertaining to the collection and analysis of such data is made for future parasitological studies

Patterns of Foraminiferal Micro-evolution and Enviromental Change in the Lower Chalk

The research tests Sheldon's Plus ҫa change model by tracking a single fossil lineage through a succession of marine environments showing geological-scale differences in background stability. Orbitally driven cyclic sediments of Cenomanian age, predominantly recording a 20 kyr precessional shift, provide both the time-frame and the main engine of environmental variability, although transgressive pulses and other events are also superimposed. The cyclicity provides spectacular geographical and temporal control,, allowing a million-year sequence to be sampled at 100 kyr intervals at three laterally adjacent sites, and partially sampled at 20 kyr and 2 kyr intervals at one of these sites. The lineage of interest is a benthic agglutinated foraminiferan, Tritaxia pyramidata, which occurs in prolific numbers; additional ecological evidence comes from a large microfossil database recovered from the same samples. The Lower Chalk benthic microfauna have very stable patterns of relative abundance, with the same species occurring in similar proportions for at least a million years. Analysis of Tritaxia's ecology identifies it as an r-selected generalist playing a keystone role in the community. During development, Tritaxia exhibits a persistent tendency to uncoil, but this tendency is strongly manifest only after average life expectancy, leading to its interpretation as a construction mistake rather than a product of design. This developmental quirk sheds light on the grain and texture of the morphospace through which Tritaxia is forced to navigate, significantly limiting its evolutionary potential. The result is a lineage that achieves a million years' worth of wobbly stasis, largely because it is boxed into a small corner of morphospace by the joint influence of a narrow developmental channel and competitive interference from other species. The dynamics, of this process predominantly support the Plus ҫa change model, even though not all the predicted patterns are found

Study on open science: The general state of the play in Open Science principles and practices at European life sciences institutes

Nowadays, open science is a hot topic on all levels and also is one of the priorities of the European Research Area. Components that are commonly associated with open science are open access, open data, open methodology, open source, open peer review, open science policies and citizen science. Open science may a great potential to connect and influence the practices of researchers, funding institutions and the public. In this paper, we evaluate the level of openness based on public surveys at four European life sciences institute

Origin of the Moon

edited by W.K. Hartmann, R.J. Phillips, G.J. TaylorHistory--Dynamical Constraints--Geochemical Constraints--Geophysical Constraints--Theories and Processes of Origin 1, Lunar Formation Involving Capture or Fission--Theories and Processes of Origin 2, Considerations Involving Large Bodies in the Environment of Primordial Earth, and Chances for Close Approaches or Impacts--Theories and Processes of Origin 3, Lunar Formation Triggered by Large Impact--Theories and Processes of Origin 4, Models Emphasizing Coaccretion or Evolution of a Circumterrestrial Swarm, of Whatever Origin

A multi-attribute value assessment method for the early product development phase with application to the business airplane industry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2005.Includes bibliographical references (p. 327-339).(cont.) market. The method is also used to extract quantitative evidence indicating the existence of enterprise-related attributes for consumer value in products. Marking the first independent review of the loss function-based value method, this study finds that the Relative Value Index is superior to existing value methods at retaining simplicity of implementation and minimal data requirements while maintaining a firm grounding in economics and consumer choice theory. The method is shown to be useful for estimation, though robustness of the results is not certain when used in this manner, and may also be extended to the analysis of large-scale engineering systems and their value to society.The early phase of product development, sometimes referred to as the fuzzy front-end, is critical to the success of enterprises and plays a dominant role in the formation and execution of corporate strategy. In addition, it has been argued that the concept of consumer value is central to effective product development. In this research, a new product value assessment method is established for the fuzzy front-end of business airplane development. Existing value assessment techniques used in the business aviation industry are found to poorly balance the theoretical rigor of the method with the ease of use and accuracy required by practitioners in early product development. A recently-developed multi-attribute value method, based on Taguchi's loss function approach to quality assessment, is modified and extended in this study and applied for the first time to the domain of business aviation. A comprehensive 40-year historical product database is developed for use in testing and evaluating the method, referred to as the Relative Value Index (RVI), enabling the scope of value method appraisal to be expanded to an industry-wide examination over a significant time span. A top-down approach is developed for calibrating value models to empirical market data via attribute weighting factors. Sensitivity analyses and Monte Carlo simulations are developed to test the RVI method's robustness and the reliability of the results, enabling a rigorous definition of the determinants of product competition in this industry. This methodology is a useful advance in the methods to extract objective findings from historical industry market activities. The RVI approach is used to develop evidence in support of a ratio theory of product price and value differentiation in the business airplaneby Troy D. Downen.Ph.D