A spatial statistic to determine appropriate field sampling size for linking image and field data

Proceedings of the 11th Australasian Remote Sensing and Photogrammetry Conference

Sampling and measurement methods for a study of childhood refractive error in a UK population

Background There is a paucity of data describing the prevalence of childhood refractive error in the United Kingdom. The Northern Ireland Childhood Errors of Refraction study, along with its sister study the Aston Eye Study, are the first population-based surveys of children using both random cluster sampling and cycloplegic autorefraction to quantify levels of refractive error in the United Kingdom. Methods Children aged 6–7 years and 12–13 years were recruited from a stratified random sample of primary and post-primary schools, representative of the population of Northern Ireland as a whole. Measurements included assessment of visual acuity, oculomotor balance, ocular biometry and cycloplegic binocular open-field autorefraction. Questionnaires were used to identify putative risk factors for refractive error. Results 399 (57%) of 6–7 years and 669 (60%) of 12–13 years participated. School participation rates did not vary statistically significantly with the size of the school, whether the school is urban or rural, or whether it is in a deprived/non-deprived area. The gender balance, ethnicity and type of schooling of participants are reflective of the Northern Ireland population. Conclusions The study design, sample size and methodology will ensure accurate measures of the prevalence of refractive errors in the target population and will facilitate comparisons with other population-based refractive data.

Quantifying the pathology of neurodegenerative disorders:Quantitative measurements, sampling strategies and data analysis

The use of quantitative methods has become increasingly important in the study of neurodegenerative disease. Disorders such as Alzheimer's disease (AD) are characterized by the formation of discrete, microscopic, pathological lesions which play an important role in pathological diagnosis. This article reviews the advantages and limitations of the different methods of quantifying the abundance of pathological lesions in histological sections, including estimates of density, frequency, coverage, and the use of semiquantitative scores. The major sampling methods by which these quantitative measures can be obtained from histological sections, including plot or quadrat sampling, transect sampling, and point-quarter sampling, are also described. In addition, the data analysis methods commonly used to analyse quantitative data in neuropathology, including analyses of variance (ANOVA) and principal components analysis (PCA), are discussed. These methods are illustrated with reference to particular problems in the pathological diagnosis of AD and dementia with Lewy bodies (DLB).

Independent detectors for expansion and rotation, and for orthogonal components of deformation

It is well known that optic flow - the smooth transformation of the retinal image experienced by a moving observer - contains valuable information about the three-dimensional layout of the environment. From psychophysical and neurophysiological experiments, specialised mechanisms responsive to components of optic flow (sometimes called complex motion) such as expansion and rotation have been inferred. However, it remains unclear (a) whether the visual system has mechanisms for processing the component of deformation and (b) whether there are multiple mechanisms that function independently from each other. Here, we investigate these issues using random-dot patterns and a forced-choice subthreshold summation technique. In experiment 1, we manipulated the size of a test region that was permitted to contain signal and found substantial spatial summation for signal components of translation, expansion, rotation, and deformation embedded in noise. In experiment 2, little or no summation was found for the superposition of orthogonal pairs of complex motion patterns (eg expansion and rotation), consistent with probability summation between pairs of independent detectors. Our results suggest that optic-flow components are detected by mechanisms that are specialised for particular patterns of complex motion.

Spatially orthogonal chemical functionalization of a hierarchical pore network for catalytic cascade reactions

The chemical functionality within porous architectures dictates their performance as heterogeneous catalysts; however, synthetic routes to control the spatial distribution of individual functions within porous solids are limited. Here we report the fabrication of spatially orthogonal bifunctional porous catalysts, through the stepwise template removal and chemical functionalization of an interconnected silica framework. Selective removal of polystyrene nanosphere templates from a lyotropic liquid crystal-templated silica sol–gel matrix, followed by extraction of the liquid crystal template, affords a hierarchical macroporous–mesoporous architecture. Decoupling of the individual template extractions allows independent functionalization of macropore and mesopore networks on the basis of chemical and/or size specificity. Spatial compartmentalization of, and directed molecular transport between, chemical functionalities affords control over the reaction sequence in catalytic cascades; herein illustrated by the Pd/Pt-catalysed oxidation of cinnamyl alcohol to cinnamic acid. We anticipate that our methodology will prompt further design of multifunctional materials comprising spatially compartmentalized functions.

Some analytical aspects of sampling plans

This thesis reports on the results of the analyses of certain aspects of sampling inspection plans. The investigation has been confined to attributes (as distinct from variables) plans and in this respect.the analyses have been concerned with two main aspects of single and double plans. These are:- (i) the Average Outgoing Quality Limit (AOQL) of the plan. (ii) the Average Sample Number (ASN) of the plan. In the former connection the investigation has been concerned with the evaluation of the AOQL analytically and the determination of the fraction defective of the incoming material to give the AOQL. The analyses have been applied to both single and double sampling plans, In the latter connection the investigation has been concerned with the evaluation of the maximum ASN analytically and the determination of the fraction defective of the incoming material to give the maximum value of ASN. The analyses have been confined only to double sampling plans because in the case of single sampling the ASN is constant and is equal to n, the sample size.

House building productivity : a study of labour requirements on Scottish house building sites using activity sampling methods

This study is concerned with labour productivity in traditional house building in Scotland. Productivity is a measure of the effective use of resources and provides vital benefits that can be combined in a number of ways. The introduction gives the background to two Scottish house building sites (Blantyre and Greenfield) that were surveyed by the Building Research Establishment (BEE) activity sampling method to provide the data for the study. The study had two main objectives; (1) summary data analysis in average manhours per house between all the houses on the site, and (2) detailed data analysis in average manhours for each house block on the site. The introduction also provides a literature review related to the objectives. The method is outlined in Chapter 2, the sites are discussed in Chapter 3, and Chapter 4 covers the method application on each site and a method development made in the study. The summary data analysis (Chapter 5) compares Blantyre and Greenfield, and two previous BEE surveys in England. The main detailed data analysis consisted of three forms, (Chapters 6, 7 and 8) each applied to a set of operations. The three forms of analysis were variations in average manhours per house for each house block on the site compared with; (1) block construction order, (2) average number of separate visits per house made by operatives to each block to complete an operation, and (3) average number of different operatives per house employed on an operation in each block. Three miscellaneous items of detail data analysis are discussed in Chapter 9. The conclusions to the whole study state that considerable variations in manhours for repeated operations were discovered, that the numbers of visits by operatives to complete operations were large and that the numbers of different operatives employed in some operations were a factor related to productivity. A critique of the activity sampling method suggests that the data produced is reliable in summary form and can give a good context for more detailed data collection. For future work, this could take the form of selected operations, with the context of an activity sampling survey, that wuld be intensively surveyed by other methods.