A Power-Enhanced Algorithm for Spatial Anomaly Detection in Binary Labelled Point Data Using the Spatial Scan Statistic [postprint]

This paper presents a novel modification to an existing algorithm for spatial anomaly detection in binary labeled point data sets, using the Bernoulli version of the Spatial Scan Statistic. We identify a potential ambiguity in p-values produced by Monte Carlo testing, which (by the selection of the most conservative p-value) can lead to sub-optimal power. When such ambiguity occurs, the modification uses a very inexpensive secondary test to suggest a less conservative p-value. Using benchmark tests, we show that this appears to restore power to the expected level, whilst having similarly retest variance to the original. The modification also appears to produce a small but significant improvement in overall detection performance when multiple anomalies are present

A pilot inference study for a beta-Bernoulli spatial scan statistic

The Bernoulli spatial scan statistic is used to detect localised clusters in binary labelled point data, such as that used in spatial or spatio-temporal case/control studies. We test the inferential capability of a recently developed beta-Bernoulli spatial scan statistic, which adds a beta prior to the original statistic. This pilot study, which includes two test scenarios with 6,000 data sets each, suggests a marked increase in power for a given false alert rate. We suggest a more extensive study would be worthwhile to corroborate the findings. We also speculate on an explanation for the observed improvement

A spatial accuracy assessment of an alternative circular scan method for Kulldorff's spatial scan statistic

This paper concerns the Bernoulli version of Kulldorff’s spatial scan statistic, and how accurately it identifies the exact centre of approximately circular regions of increased spatial density in point data. We present an alternative method of selecting circular regions that appears to give greater accuracy. Performance is tested in an epidemiological context using manifold synthetic case-control datasets. A small, but statistically significant, improvement is reported. The power of the alternative method is yet to be assessed

A graph-theory method for pattern identification in geographical epidemiology - a preliminary application to deprivation and mortality

Background: Graph theoretical methods are extensively used in the field of computational chemistry to search datasets of compounds to see if they contain particular molecular substructures or patterns. We describe a preliminary application of a graph theoretical method, developed in computational chemistry, to geographical epidemiology in relation to testing a prior hypothesis. We tested the methodology on the hypothesis that if a socioeconomically deprived neighbourhood is situated in a wider deprived area, then that neighbourhood would experience greater adverse effects on mortality compared with a similarly deprived neighbourhood which is situated in a wider area with generally less deprivation. Methods: We used the Trent Region Health Authority area for this study, which contained 10,665 census enumeration districts (CED). Graphs are mathematical representations of objects and their relationships and within the context of this study, nodes represented CEDs and edges were determined by whether or not CEDs were neighbours (shared a common boundary). The overall area in this study was represented by one large graph comprising all CEDs in the region, along with their adjacency information. We used mortality data from 1988-1998, CED level population estimates and the Townsend Material Deprivation Index as an indicator of neighbourhood level deprivation. We defined deprived CEDs as those in the top 20% most deprived in the Region. We then set out to classify these deprived CEDs into seven groups defined by increasing deprivation levels in the neighbouring CEDs. 506 (24.2%) of the deprived CEDs had five adjacent CEDs and we limited pattern development and searching to these CEDs. We developed seven query patterns and used the RASCAL (Rapid Similarity Calculator) program to carry out the search for each of the query patterns. This program used a maximum common subgraph isomorphism method which was modified to handle geographical data. Results: Of the 506 deprived CEDs, 10 were not identified as belonging to any of the seven groups because they were adjacent to a CED with a missing deprivation category quintile, and none fell within query Group 1 (a deprived CED for which all five adjacent CEDs were affluent). Only four CEDs fell within Group 2, which was defined as having four affluent adjacent CEDs and one non-affluent adjacent CED. The numbers of CEDs in Groups 3-7 were 17, 214, 95, 81 and 85 respectively. Age and sex adjusted mortality rate ratios showed a non-significant trend towards increasing mortality risk across Groups (Chi-square = 3.26, df = 1, p = 0.07). Conclusion: Graph theoretical methods developed in computational chemistry may be a useful addition to the current GIS based methods available for geographical epidemiology but further developmental work is required. An important requirement will be the development of methods for specifying multiple complex search patterns. Further work is also required to examine the utility of using distance, as opposed to adjacency, to describe edges in graphs, and to examine methods for pattern specification when the nodes have multiple attributes attached to them

Mechanical Characterization of Expanded Polystyrene Spheres Embed Sandwich Composites for Packaging Applications

This paper addresses on study of development of new packaging material comprising Expanded Polystyrene Spheres (EPS) embedded epoxy polymer based sandwich composites with aluminium skin. The density of the packing material is controlled by varying the volume of embedded spheres. In this study, the Flexural and Compression performance of Expanded Polystyrene Spheres (EPS) embedded polymer based sandwich composites with aluminium skin are investigated. The EPS volume percent in the core is 25% with epoxy matrix which makes the the density less than 1 g/cm3 for the composite. The fabricated Sandwich Composite are very light weight, the density is less than 1 g/cm3 so it can able to float in water. Here for the same volume fraction of 25%. EPS are arranged in square pattern and hexagonal pattern in the sandwich composites. The compression strength and flexural strength for the two type of pattern arrangements were studied in experimental method

Associations between neighbourhood environmental factors and the uptake and effectiveness of a brief intervention to increase physical activity

Background Evidence suggests behavioural interventions may exacerbate health inequalities, potentially due to differences in uptake or effectiveness. We used a physical activity intervention targeting deprived communities to identify neighbourhood-level factors that might explain differences in programme impact. Methods Individuals aged 40–65 were sent a postal invitation offering a brief intervention to increase physical activity. We used postcodes linkage to determine whether neighbourhood indicators of deprivation, housing, crime and proximity to green spaces and leisure facilities predicted uptake of the initial invitation or an increase in physical activity level in those receiving the brief intervention. Results A total of 4134 (6.8%) individuals responded to the initial invitation and of those receiving the intervention and contactable after 3 months, 486 (51.6%) reported an increase in physical activity. Area deprivation scores linked to postcodes predicted intervention uptake, but not intervention effectiveness. Neighbourhood indicators did not predict either uptake or intervention effectiveness. Conclusions The main barrier to using brief intervention invitations to increase physical activity in deprived, middle-aged populations was the low uptake of an intervention requiring significant time and motivation from participants. Once individuals have taken up the intervention offer, neighbourhood characteristics did not appear to be significant barriers to successful lifestyle change

Reduced Form Estimation Of The Noise Trading Model

In this paper, we develop and implement the reduced form version of the Noise Trading Model in the Indian stock market, which we had proposed in an earlier paper. We show how to estimate the model without making any assumptions regarding the cross-sectional dependence that may exist among the individual stocks. This allows us to come up with precise estimates of the share of information versus noise in the opening stock price. To be specific, information accounts for 52% of the variance of the opening stock price and noise contributes to the rest. When we split the overall sample into weekend versus weekday, we find that the information share of the opening price is significantly higher after a weekend at 72% compared to 46% during the rest of the week

Reduced Form Estimation Of The Noise Trading Model

In this paper, we develop and implement the reduced form version of the Noise Trading Model in the Indian stock market, which we had proposed in an earlier paper. We show how to estimate the model without making any assumptions regarding the cross-sectional dependence that may exist among the individual stocks. This allows us to come up with precise estimates of the share of information versus noise in the opening stock price. To be specific, information accounts for 52% of the variance of the opening stock price and noise contributes to the rest. When we split the overall sample into weekend versus weekday, we find that the information share of the opening price is significantly higher after a weekend at 72% compared to 46% during the rest of the week

Empirical Implications of Arbitrage-Free Asset Markets

The martingale-equivalence condition delivered by a non-arbitrage assumption in complete asset markets has implications for fine-time-unit asset price behavior that can be rejected with finite spans of data. A class of stochastic processes that could model such deviations from martingale-equivalence is proposed.Asset market, asset pricing

Statin induced myopathy: a case report

Statin-induced necrotizing autoimmune myopathy is an immune-mediated necrotizing myopathy related to the use of statins. It is a very rare disease, which usually presents with proximal muscle weakness and frank elevation in creatine kinase levels. Stopping statin and the use of immunosuppressive therapy are considered the mainstay therapy. Herein, we present a case of a 75-year-old patient with statin-induced myopathy based on the presence of proximal muscle weakness, magnetic resonance findings. The patient was treated with IVIg and corticosteroid therapy with a particularly good response to intravenous immunoglobulin. However, medications are accompanied by the not so friendly adverse events. Through this report we highlight the importance of understanding. This report highlights the importance of timely diagnosis and early use of combined immunosuppressive therapy to improve patients' outcome affected by this rare disease