Linking public issues with private troubles: panel studies in developing countries

Accompanying the call for increased evidence-based policy the developed world is implementing more longitudinal panel studies which periodically gather information about the same people over a number of years. Panel studies distinguish between transitory and persistent states (e.g. poverty, unemployment) and facilitate causal explanations of relationships between variables. However, they are complex and costly. A growing number of developing countries are now implementing or considering starting panel studies. The objectives of this paper are to identify challenges that arise in panel studies, and to give examples of how these have been addressed in resource-constrained environments. The main issues considered are: the development of a conceptual framework which links macro and micro contexts; sampling the cohort in a cost-effective way; tracking individuals; ethics and data management and analysis. Panel studies require long term funding, a stable institution and an acceptance that there will be limited value for money in terms of results from early stages, with greater benefits accumulating in the study's mature years. Copyright © 2003 John Wiley & Sons, Ltd.

A likelihood ratio appropach to family-based association studies with covariates

We introduce a procedure for association based analysis of nuclear families that allows for dichotomous and more general measurements of phenotype and inclusion of covariate information. Standard generalized linear models are used to relate phenotype and its predictors. Our test procedure, based on the likelihood ratio, unifies the estimation of all parameters through the likelihood itself and yields maximum likelihood estimates of the genetic relative risk and interaction parameters. Our method has advantages in modelling the covariate and gene-covariate interaction terms over recently proposed conditional score tests that include covariate information via a two-stage modelling approach. We apply our method in a study of human systemic lupus erythematosus and the C-reactive protein that includes sex as a covariate.

Efficient and accurate experimental design for enzyme kinetics: Bayesian studies reveal a systematic approach

In areas such as drug development, clinical diagnosis and biotechnology research, acquiring details about the kinetic parameters of enzymes is crucial. The correct design of an experiment is critical to collecting data suitable for analysis, modelling and deriving the correct information. As classical design methods are not targeted to the more complex kinetics being frequently studied, attention is needed to estimate parameters of such models with low variance. We demonstrate that a Bayesian approach (the use of prior knowledge) can produce major gains quantifiable in terms of information, productivity and accuracy of each experiment. Developing the use of Bayesian Utility functions, we have used a systematic method to identify the optimum experimental designs for a number of kinetic model data sets. This has enabled the identification of trends between kinetic model types, sets of design rules and the key conclusion that such designs should be based on some prior knowledge of K-M and/or the kinetic model. We suggest an optimal and iterative method for selecting features of the design such as the substrate range, number of measurements and choice of intermediate points. The final design collects data suitable for accurate modelling and analysis and minimises the error in the parameters estimated. (C) 2003 Elsevier Science B.V. All rights reserved.

What have we learnt about heavy carbenes through laser flash photolysis studies?

Time resolved gas-phase kinetic studies have contributed a great deal of fundamental information about the reactions and reactivity of heavy carbenes (silylenes, germylenes and stannylenes) during the past two decades. In this article we trace the development of our understanding through the mechanistic themes of intermediate complexes, third body assisted associations, catalysed reactions, non-observed reactions and substituent effects. Ab initio (quantum chemical) calculations have substantially assisted mechanistic interpretation and are discussed where appropriate. Trends in reactivity are identified and some signposts to future studies are indicated. This review, although detailed, is not comprehensive.

Vision 2020 - A whole life-cycle information management system for built environments

A whole life-cycle information management vision is proposed, the organizational requirements for the realization of the scenario is investigated. Preliminary interviews with construction professionals are reported. Discontinuities at information transfer throughout life-cycle of built environments are resulting from lack of coordination and multiple data collection/storage practices. A more coherent history of these activities can improve the work practices of various teams by augmenting decision making processes and creating organizational learning opportunities. Therefore, there is a need for unifying these fragmented bits of data to create a meaningful, semantically rich and standardized information repository for built environment. The proposed vision utilizes embedded technologies and distributed building information models. Two diverse construction project types (large one-off design, small repetitive design) are investigated for the applicability of the vision. A functional prototype software/hardware system for demonstrating the practical use of this vision is developed and discussed. Plans for case-studies for validating the proposed model at a large PFI hospital and housing association projects are discussed.

Effects of active information processing on the understanding of risk information

Two experiments investigated effects of active processing of risk information on participants' understanding and judgments. It was hypothesized that more active processing would lead to better understanding and differences in affective judgments (e.g. increased satisfaction and reduced perceived risk to health). In both experiments participants were given a written scenario about their being prescribed a fictitious medication. This medication was said to cause side effects in 2% of people who took it. Before answering a series of written questions, participants in the active conditions of both experiments were asked to carry out a reflective task (portraying the size of risk on a bar chart in Experiment 1 and answering a reflective question in Experiment 2). The results showed that active participants rated the likelihood of experiencing possible side effects significantly lower than passive participants (Experiment 1), and that active participants were significantly more satisfied with the information and judged perceived risk to health from taking the medication significantly lower than passive participants (Experiment 2). In both experiments, active participants were significantly more correct in their probability and frequency estimates. The studies demonstrate that active processing of risk information leads to improved understanding of the information given. This has important implications for risk communication. In the context of health, better understanding should lead to improved decision-making and health outcomes. Copyright (C) 2004 John Wiley Sons, Ltd.

Communicating information about medication: the benefits of making it personal

Two experiments, using a controlled empirical methodology, investigated the effects of presenting information about medicines using a more personalised style of expression. In both studies, members of the general public were given a hypothetical scenario about visiting the doctor, being diagnosed with a particular illness, and being prescribed a medication. They were also given a written explanation about the medicine and were asked to provide ratings on a number of measures, including satisfaction, perceived risk to health, and intention to comply. In Experiment 1 the explanation focused only on possible side effects of the medicine, whereas in Experiment 2 a fuller explanation was provided, which included information about the illness, prescribed drug, its dosage and contraindications as well as its side effects. In both studies, use of a more personalised style resulted in significantly higher ratings of satisfaction and significantly lower ratings of likelihood of side effects occurring and of perceived risk to health. In Experiment 2 it also led to significantly improved recall for the written information.

Combining Human and Machine Brains - Practical systems in information & control

In this paper a look is taken at how the use of implant technology can be used to either increase the range of the abilities of a human and/or diminish the effects of a neural illness, such as Parkinson's Disease. The key element is the need for a clear interface linking the human brain directly with a computer. The area of interest here is the use of implant technology, particularly where a connection is made between technology and the human brain and/or nervous system. Pilot tests and experimentation are invariably carried out apriori to investigate the eventual possibilities before human subjects are themselves involved. Some of the more pertinent animal studies are discussed here. The paper goes on to describe human experimentation, in particular that carried out by the author himself, which led to him receiving a neural implant which linked his nervous system bi-directionally with the internet. With this in place neural signals were transmitted to various technological devices to directly control them. In particular, feedback to the brain was obtained from the fingertips of a robot hand and ultrasonic (extra) sensory input. A view is taken as to the prospects for the future, both in the near term as a therapeutic device and in the long term as a form of enhancement.

Quality of tender documents: case studies from the UK

Tendering is one of the stages in construction procurement that requires extensive information and documents exchange. However, tender documents are not always clear in practice. The aim of this study was to ascertain the clarity and adequacy of tender documents used in practice. Access was negotiated into two UK construction firms and the whole tender process for two projects was shadowed for 6-7 weeks in each firm using an ethnographic approach. A significant amount of tender queries, amendments and addenda were recorded. This showed that quality of tender documentation is still a problem in construction despite the existence of standards like Co-ordinated Project Information (1987) and British Standard 1192 (1984 and 1990) that are meant to help in producing clear and consistent project information. Poor quality tender documents are a source of inaccurate estimates, claims and disputes on contracts. Six recommendations are presented to help in improving the quality of tender documentation. Further research is needed into the recommendations to help improve the quality of tender documents, perhaps in conjunction with an industry-wide investigation into the level of incorporation of CPI principles in practice.

Fruit polyphenols and CVD risk: a review of human intervention studies.

Epidemiological evidence suggests that polyphenols may, in part, explain the cardioprotective properties of fruits. This review aims to summarise the evidence for the effects of fruit polyphenols on four risk factors of CVD: platelet function, blood pressure, vascular function and blood lipids. This review includes human dietary intervention studies investigating fruits and their polyphenols. There was some evidence to suggest that fruits containing relatively high concentrations of flavonols, anthocyanins and procyanindins, such as pomegranate, purple grapes and berries, were effective at reducing CVD risk factors, particularly with respect to anti-hypertensive effects, inhibition of platelet aggregation and increasing endothelial-dependent vasodilation than other fruits investigated. Flavanone-rich fruits, such as oranges and grapefruits, were reported to have hypocholesterolaemic effects, with little impact on other risk factors being examined. However, the evidence was limited, inconsistent and often inconclusive. This is in part due to the heterogeneity in the design of studies, the lack of controls, the relatively short intervention periods and low power in several studies. Details of the polyphenol content of the fruits investigated were also omitted in some studies, negating comparison of data. It is recommended that large, well-powered, long-term human dietary intervention studies investigating a wider range of fruits are required to confirm these observations. Investigations into the potential synergistic effects of polyphenols on a combination of CVD risk markers, dose–response relationships and standardisation in methodology would facilitate the comparison of studies and also provide valuable information on the types of fruits which could confer protection against CVD.

Sterically controlled recognition of macromolecular sequence information by molecular tweezers

Sequence-specific binding is demonstrated between pyrene-based tweezer molecules and soluble, high molar mass copolyimides. The binding involves complementary pi - pi stacking interactions, polymer chain-folding, and hydrogen bonding and is extremely sensitive to the steric environment around the pyromellitimide binding-site. A detailed picture of the intermolecular interactions involved has been obtained through single-crystal X-ray studies of tweezer complexes with model diimides. Ring-current magnetic shielding of polyimide protons by the pyrene '' arms '' of the tweezer molecule induces large complexation shifts of the corresponding H-1 NMR resonances, enabling specific triplet sequences to be identified by their complexation shifts. Extended comonomer sequences (triplets of triplets in which the monomer residues differ only by the presence or absence of a methyl group) can be '' read '' by a mechanism which involves multiple binding of tweezer molecules to adjacent diimide residues within the copolymer chain. The adjacent-binding model for sequence recognition has been validated by two conceptually different sets of tweezer binding experiments. One approach compares sequence-recognition events for copolyimides having either restricted or unrestricted triple-triplet sequences, and the other makes use of copolymers containing both strongly binding and completely nonbinding diimide residues. In all cases the nature and relative proportions of triple-triplet sequences predicted by the adjacent-binding model are fully consistent with the observed H-1 NMR data.

Markers of intestinally-derived lipoproteins: application to studies of altered diet and meal fatty acid compositions

BACKGROUND AND AIM: The atherogenic potential of dietary derived lipids, chylomicrons (CM) and their remnants (CMr) is now becoming more widely recognised. To investigate factors effecting levels of CM and CMr and their importance in coronary heart disease risk it is essential to use a specific method of quantification. Two studies were carried out to investigate: (i) effects of increased daily intake of long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA), and (ii) effects of increasing meal monounsaturated fatty acid (MUFA) content on the postprandial response of intestinally-derived lipoproteins. The contribution of the intestinally-derived lipoproteins to total lipaemia was assessed by triacylglycerol-rich lipoprotein (TRL) apolipoprotein B-48 (apo B-48) and retinyl ester (RE) concentrations. METHODS AND RESULTS: In a randomised controlled crossover trial (placebo vs LC n-3 PUFA) a mean daily intake of 1.4 g/day of LC n-3 PUFA failed to reduce fasting and postprandial triacylglycerol (TAG) response in 9 healthy male volunteers. Although the pattern and nature of the apo B-48 response was consistent with the TAG response following the two diets, the postprandial RE response differed on the LC n-3 PUFA diet with a lower early RE response and a delayed and more marked increase in RE in the late postprandial period compared with the control diet, but the differences did not reach levels of statistical significance. In the meal study there was no effect of MUFA/SFA content on the total lipaemic response to the meals nor on the contribution of intestinally derived lipoproteins evaluated as TAG, apo B-48 and RE responses in the TRL fraction. In both studies, the RE and apo B-48 measurements provided broadly similar information with respect to lack of effects of dietary or meal fatty acid composition and the presence of single or multiple peak responses. However the apo B-48 and RE measurements differed with respect to the timing of their peak response times, with a delayed RE peak, relalive to apo B-48, of approximately 2-3 hours for the LC n-3 PUFA diet (p = 0.002) study and 1-1.5 hours for the meal MUFA/SFA study. CONCLUSIONS: It was concluded that there are limitations of using RE as a specific CM marker, apo B-48 quantitation was found to be a more appropriate method for CM and CMr quantitation. However it was still considered of value to measure RE as it provided additional information regarding the incorporation of other constituents into the CM particle.