Showing papers by "Edinburgh Napier University published in 2010"

Silane coupling agents used for natural fiber/polymer composites: A review

Abstract: Natural fiber reinforced polymer composites (NFPCs) provide the customers with more alternatives in the material market due to their unique advantages. Poor fiber–matrix interfacial adhesion may, however, negatively affect the physical and mechanical properties of the resulting composites due to the surface incompatibility between hydrophilic natural fibers and non-polar polymers (thermoplastics and thermosets). A variety of silanes (mostly trialkoxysilanes) have been applied as coupling agents in the NFPCs to promote interfacial adhesion and improve the properties of composites. This paper reviews the recent progress in using silane coupling agents for NFPCs, summarizes the effective silane structures from the silane family, clarifies the interaction mechanisms between natural fibers and polymer matrices, and presents the effects of silane treatments on the mechanical and outdoor performance of the resulting composites.

A review of the in vivo and in vitro toxicity of silver and gold particulates: Particle attributes and biological mechanisms responsible for the observed toxicity

Abstract: This review is concerned with evaluating the toxicity associated with human exposure to silver and gold nanoparticles (NPs), due to the relative abundance of toxicity data available for these particles, when compared to other metal particulates. This has allowed knowledge on the current understanding of the field to be gained, and has demonstrated where gaps in knowledge are. It is anticipated that evaluating the hazards associated with silver and gold particles will ultimately enable risk assessments to be completed, by combining this information with knowledge on the level of human exposure. The quantity of available hazard information for metals is greatest for silver particulates, due to its widespread inclusion within a number of diverse products (including clothes and wound dressings), which primarily arises from its antibacterial behaviour. Gold has been used on numerous occasions to assess the biodistribution and cellular uptake of NPs following exposure. Inflammatory, oxidative, genotoxic, and cytotoxic consequences are associated with silver particulate exposure, and are inherently linked. The primary site of gold and silver particulate accumulation has been consistently demonstrated to be the liver, and it is therefore relevant that a number of in vitro investigations have focused on this potential target organ. However, in general there is a lack of in vivo and in vitro toxicity information that allows correlations between the findings to be made. Instead a focus on the tissue distribution of particles following exposure is evident within the available literature, which can be useful in directing appropriate in vitro experimentation by revealing potential target sites of toxicity. The experimental design has the potential to impact on the toxicological observations, and in particular the use of excessively high particle concentrations has been observed. As witnessed for other particle types, gold and silver particle sizes are influential in dictating the observed toxicity, with smaller particles exhibiting a greater response than their larger counterparts, and this is likely to be driven by differences in particle surface area, when administered at an equal-mass dose. A major obstacle, at present, is deciphering whether the responses related to silver nanoparticulate exposure derive from their small size, or particle dissolution contributes to the observed toxicity. Alternatively, a combination of both may be responsible, as the release of ions would be expected to be greater for smaller particles.

Dynamic networks and behavior: separating selection from influence

Abstract: A recurrent problem in the analysis of behavioral dynamics, given a simultaneously evolving social network, is the difficulty of separating the effects of partner selection from the effects of social influence. Because misattribution of selection effects to social influence, or vice versa, suggests wrong conclusions about the social mechanisms underlying the observed dynamics, special diligence in data analysis is advisable. While a dependable and validmethod would benefit several research areas, according to the best of our knowledge, it has been lacking in the extant literature. In this paper, we present a recently developed family of statistical models that enables researchers to separate the two effects in a statistically adequate manner. To illustrate our method, we investigate the roles of homophile selection and peer influence mechanisms in the joint dynamics of friendship formation and substance use among adolescents. Making use of a three-wave panel measured in the years 1995–1997 at a school in ...

A critical review of the biological mechanisms underlying the in vivo and in vitro toxicity of carbon nanotubes: The contribution of physico-chemical characteristics

Abstract: This critical review of the available human health safety data, relating to carbon nanotubes (CNTs), was conducted in order to assess the risks associated with CNT exposure. Determining the toxicity related to CNT exploitation is of great relevance and importance due to the increased potential for human exposure to CNTs within occupational, environmental and consumer settings. When this information is combined with knowledge on the likely exposure levels of humans to CNTs, it will enable risk assessments to be conducted to assess the risks posed to human health. CNTs are a diverse group of materials and vary with regards to their wall number (single and multi-walled CNTs are evident), length, composition, and surface chemistry. The attributes of CNTs that were identified as being most likely to drive the observed toxicity have been considered, and include CNT length, metal content, tendency to aggregate/agglomerate and surface chemistry. Of particular importance, is the contribution of the fibre paradigm to CNT toxicity, whereby the length of CNTs appears to be critical to their toxic potential. Mechanistic processes that are critical to CNT toxicity will also be discussed, with the findings insinuating that CNTs can exert an oxidative response that stimulates inflammatory, genotoxic and cytotoxic consequences. Consequently, it may transpire that a common mechanism is responsible for driving CNT toxicity, despite the fact that CNTs are a diverse population of materials. The similarity of the structure of CNTs to that of asbestos has prompted concern surrounding the exposure of humans, and so the applicability of the fibre paradigm to CNTs will be evaluated. It is also necessary to determine the systemic availability of CNTs following exposure, to determine where potential targets of toxicity are, and to thereby direct in vitro investigations within the most appropriate target cells. CNTs are therefore a group of materials whose useful exploitable properties prompts their increased production and utilization within diverse applications, so that ensuring their safety is of vital importance.

Serum thyroid-stimulating hormone concentration and morbidity from cardiovascular disease and fractures in patients on long-term thyroxine therapy

Abstract: Context: For patients on T4 replacement, the dose is guided by serum TSH concentrations, but some patients request higher doses due to adverse symptoms. Objective: The aim of the study was to determine the safety of patients having a low but not suppressed serum TSH when receiving long-term T4 replacement. Design: We conducted an observational cohort study, using data linkage from regional datasets between 1993 and 2001. Setting: A population-based study of all patients in Tayside, Scotland, was performed. Patients: All patients taking T4 replacement therapy (n = 17,684) were included. Main Outcome Measures: Fatal and nonfatal endpoints were considered for cardiovascular disease, dysrhythmias, and fractures. Patients were categorized as having a suppressed TSH (≤0.03 mU/liter), low TSH (0.04–0.4 mU/liter), normal TSH (0.4–4.0 mU/liter), or raised TSH (>4.0 mU/liter). Results: Cardiovascular disease, dysrhythmias, and fractures were increased in patients with a high TSH: adjusted hazards ratio, 1.95 (1.73–...

Effect of aspirin and NSAIDs on risk and survival from colorectal cancer

Abstract: Background Previous studies have shown that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) lower colorectal cancer (CRC) risk. However, the lowest effective NSAID dose, treatment duration, and effects on survival are not defined. In a large population-based caseecontrol study, we have explored the relationship between NSAID dose and duration, CRC risk and overall CRC-specific survival. Methods The relationship between NSAID use and CRC risk was examined in 2279 cases and 2907 controls. Subjects completed food-frequency and lifestyle questionnaires. NSAID categories were low-dose aspirin (75 mg), non-aspirin NSAIDs (NA-NSAIDs) and any NSAID. Users were defined as taking >4 tablets/week for >1 month. ORs were calculated by logistic regression models and adjusted for potential confounding factors. Effect of NSAID use on all-cause and CRCspecific mortality was estimated using Logrank tests and Cox’s hazard models. Results In all, 354 cases (15.5%) were taking low-dose aspirin compared to 526 controls (18.1%). Low-dose aspirin use was associated with decreased CRC risk (OR 0.78 95% CI 0.65 to 0.92, p¼0.004), evident after 1 year and increasing with duration of use (ptrend¼0.004). NANSAID and any NSAID use were also inversely associated with CRC. There was no demonstrable effect of NSAIDS on all-cause (HR 1.11, p¼0.22, 0.94e1.33) or CRC-specific survival (HR 1.01, p¼0.93, 0.83e1.23). Conclusion This is the first study to demonstrate a protective effect against CRC associated with the lowest dose of aspirin (75 mg per day) after only 5 years use in the general population. NSAID use prior to CRC diagnosis does not influence survival from the disease.

Review of carbon nanotubes toxicity and exposure—Appraisal of human health risk assessment based on open literature

Abstract: Carbon nanotubes (CNTs) possess many unique electronic and mechanical properties and are thus interesting for numerous novel industrial and biomedical applications. As the level of production and use of these materials increases, so too does the potential risk to human health. This study aims to investigate the feasibility and challenges associated with conducting a human health risk assessment for carbon nanotubes based on the open literature, utilising an approach similar to that of a classical regulatory risk assessment. Results indicate that the main risks for humans arise from chronic occupational inhalation, especially during activities involving high CNT release and uncontrolled exposure. It is not yet possible to draw definitive conclusions with regards the potential risk for long, straight multi-walled carbon nanotubes to pose a similar risk as asbestos by inducing mesothelioma. The genotoxic potential of CNTs is currently inconclusive and could be either primary or secondary. Possible systemic effects of CNTs would be either dependent on absorption and distribution of CNTs to sensitive organs or could be induced through the release of inflammatory mediators. In conclusion, gaps in the data set in relation to both exposure and hazard do not allow any definite conclusions suitable for regulatory decision-making. In order to enable a full human health risk assessment, future work should focus on the generation of reliable occupational, environmental and consumer exposure data. Data on toxicokinetics and studies investigating effects of chronic exposure under conditions relevant for human exposure should also be prioritised.

Setting the Research Agenda in Automated Timetabling: The Second International Timetabling Competition

Abstract: The Second International Timetabling Competition (TTC2007) opened in August 2007. Building on the success of the first competition in 2002, this sequel aimed to further develop research activity in the area of educational timetabling. The broad aim of the competition was to create better understanding between researchers and practitioners by allowing emerging techniques to be developed and tested on real-world models of timetabling problems. To support this, a primary goal was to provide researchers with models of problems faced by practitioners through incorporating a significant number of real-world constraints. Another objective of the competition was to stimulate debate within the widening timetabling research community. The competition was divided into three tracks to reflect the important variations that exist in educational timetabling within higher education. Because these formulations incorporate an increased number of “real-world” issues, it is anticipated that the competition will now set the research agenda within the field. After finishing in January 2008, final results were made available in May 2008. Along with background to the competition, the competition tracks are described here along with a brief overview of the techniques used by the competition winners.

Corporate social responsibility disclosure: A comparison between Islamic and conventional financial institutions

Abstract: Purpose – The purpose of this paper is to examine the influence of Islam on corporate social responsibility disclosure (CSRD) in Islamic financial institutions (IFIs).Design/methodology/approach – Using the content analysis approach, the paper examines the influences of Islam on CSRD by looking into the annual reports of 21 conventional financial institutions (CFIs) and 21 IFIs operating in the Gulf region.Findings – The results show significant differences in the level and the extent of the disclosure between IFIs and CFIs, largely due to the disclosure made by IFIs of religions related themes and information, including Shari'a supervisory board reports, the “Zakah” and charity donation, and free interest loan.Originality/value – This paper's contribution to the literature is twofold: the paper reveals the actual difference of CSRD between IFIs and non‐IFIs, by comparing the disclosures made by IFIs and non‐IFIs; and the paper identifies the extent of influence of Islam upon the CSRD of IFIs.

The water vapour sorption properties of Sitka spruce determined using a dynamic vapour sorption apparatus

Abstract: The water vapour sorption properties of Sitka spruce (Picea abies) have been investigated over a range of temperatures (14.2–43.8°C) using a dynamic vapour sorption apparatus. The sorption kinetics behaviour was evaluated using the parallel exponential kinetics model which has been found to give very accurate fits to the data in studies of foodstuffs or plant fibres, but has not been previously applied to sorption studies with wood. Both the adsorption and desorption kinetics curve can be deconvoluted into a fast and slow exponential process. Under conditions of adsorption, the fast process appears to be associated with the formation of monolayer water (determined using the Hailwood Horrobin model) up to a relative humidity of 20%. Under desorption, there is no clear differentiation between fast and slow processes. The area bounded by the sorption hysteresis loop reduced as the temperature at which the isotherm was measured increased, due to movement of the desorption curve only, with the adsorption curve remaining the same at all temperatures. This behaviour is consistent with sorption processes taking place on nanoporous glassy solids below the glass transition temperature. The heat of wetting was determined from the temperature dependence of the desorption isotherms by using the Clausius–Clapeyron equation, yielding results that are consistent with literature values. However, doubts are raised in this paper as to the applicability of using the Clausius–Clapeyron equation for analyses of this type.

Nano-silver - feasibility and challenges for human health risk assessment based on open literature.

Abstract: This study aims at investigating feasibility and challenges associated with conducting a human health risk assessment for nano-silver based on the open literature by following an approach similar to a classical regulatory risk assessment. Gaps in the available data set, both in relation to exposures and hazard, do not allow reaching any definite conclusions that could be used for regulatory decision making. Results show that repeated inhalation in the workplace and possibly consumer inhalation may cause risks. Also (uncontrolled) nano-silver drug intake and burn treatment of large parts of the body with wound dressings may cause risks. Main future work should focus on generating occupational and consumer exposure data, as well as toxicity data on absorption (are particles or only ions absorbed?), information on genetoxicity, and further information on the toxicity following inhalation exposure to sizes and agglomeration states as uncounted in the workplace.

Multicentre randomised controlled trial of the clinical and cost-effectiveness of a bypass-surgery-first versus a balloon-angioplasty-first revascularisation strategy for severe limb ischaemia due to infrainguinal disease. The Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial

Abstract: Objective To compare a 'bypass-surgery-first' with a 'balloon-angioplasty-first' revascularisation strategy in patients with severe limb ischaemia (SLI) due to infrainguinal disease requiring immediate/early revascularisation. Design A stratified randomised controlled trial. A Delphi consensus study of vascular surgeons' and interventional radiologists' views on SLI treatment was performed before the trial. Setting Twenty-seven UK hospitals. Participants Patients presenting with SLI as the result of infrainguinal atherosclerosis and who, in the opinion of the responsible consultant vascular surgeon and interventional radiologist, required and were suitable for both surgery and angioplasty. Interventions Patients were randomised to either 'bypass-surgery-first' or 'balloon-angioplasty-first' revascularisation strategies. Main outcome measures The primary end point was amputation-free survival (AFS); secondary end points were overall survival (OS), health-related quality of life (HRQoL) and cost-effective use of hospital resources. Results AFS at 1 and 3 years was not significantly different for surgery and angioplasty. Interim analysis showed that surgery was associated with significantly lower immediate failure, higher 30-day morbidity and lower 12-month reintervention rates than angioplasty; 30-day mortality was similar. Beyond 2 years from randomisation, hazard ratios (HRs) were significantly reduced for both AFS (adjusted HR 0.37; 95% CI 0.17 to 0.77; p = 0.008) and OS (HR 0.34; 95% CI 0.17 to 0.71; p = 0.004) for surgery relative to angioplasty. By 2008 all but four patients had been followed for 3 years, some for over 7 years: 250 (56%) were dead, 168 (38%) were alive without amputation and 30 (7%) were alive with amputation. Considering the follow-up period as a whole, AFS and OS did not differ between treatments but for patients surviving beyond 2 years from randomisation, bypass was associated with reduced HRs for AFS (HR 0.85; 95% CI 0.50 to 1.07; p = 0.108) and OS (HR 0.61; 95% CI 0.50 to 0.75; p = 0.009), equating to an increase in restricted mean OS of 7.3 months (p = 0.02) and AFS of 5.9 months (p = 0.06) during the subsequent follow-up period. Vein bypasses and angioplasties performed better than prosthetic bypasses. HRQoL was non-significantly better in the surgery group; amputation was associated with a significant reduction in HRQoL. Over the first year, hospital costs for bypass were significantly higher (difference 5420 pounds; 95% CI 1547 pounds to 9294 pounds) than for angioplasty. However, by 3 and at 7 years the differences in cost between the two strategies were no longer significant. Patients randomised to surgery lived, on average, 29 days longer at an additional average cost of 2310 pounds. A 36-month perspective showed not significantly different mean quality-adjusted life times for angioplasty and surgery. The Delphi study revealed substantial disagreement between and among surgeons and radiologists on the appropriateness of bypass surgery or balloon angioplasty. Conclusions The findings of our study suggest that in patients with SLI due to infrainguinal disease the decision whether to perform bypass surgery or balloon angioplasty first appears to depend upon anticipated life expectancy. Patients expected to live less than 2 years should usually be offered balloon angioplasty first as it is associated with less morbidity and cost, and such patients are unlikely to enjoy the longer-term benefits of surgery. By contrast, those patients expected to live beyond 2 years should usually be offered bypass surgery first, especially where a vein is available as a conduit. Many patients who could not undergo a vein bypass would probably have been better served by a first attempt at balloon angioplasty than prosthetic bypass. The failure rate of angioplasty in SLI is high (c. 25%) and patients who underwent bypass after failed angioplasty fared significantly worse than those who underwent surgery as their first procedure. The interests of a significant proportion of BASIL patients may have been best served by primary amputation followed by high-quality rehabilitation. Further research is required to confirm or refute the BASIL findings and recommendations; validate the BASIL survival prediction model in a separate cohort of patients with SLI; examine the clinical and cost-effectiveness of new endovascular techniques and devices; and compare revascularisation with primary amputation and with best medical and nursing care in those SLI patients with the poorest survival prospects. Trial registration Current Controlled Trials ISRCTN45398889.

A survey of multiple tree visualisation

Abstract: This article summarises the current state of research into multiple tree visualisations. It discusses the spectrum of current representation techniques used on single trees, pairs of trees and finally multiple trees, in order to identify which representations are best suited to particular tasks and to find gaps in the representation space, in which opportunities for future multiple tree visualisation research may exist. The application areas from where multiple tree data are derived are enumerated, and the distinct structures that multiple trees make in combination with each other and the effect on subsequent approaches to their visualisation are discussed, along with the basic high-level goals of existing multiple tree visualisations.

Changing reasons for public private partnerships.

Abstract: This article considers the micro- and macro-economic benefits and costs of PPPs and some implications of implementing new international accounting standards. If public sector financial costs are forced to move ‘on balance sheet’, then there are likely to be impacts on the use in PPPs by governments and other public bodies. This may move the basis of PPP choice towards a more level playing-field with other financing sources, potentially give a more realistic measure of future public commitments and liabilities and reduce incentives to use PPPs for budget enlargement. There may be a refocusing upon the potential efficiency gains of PPPs and a reduction in their use, in some cases.

High mangrove density enhances surface accretion, surface elevation change, and tree survival in coastal areas susceptible to sea-level rise

Abstract: Survival, growth, aboveground biomass accumulation, sediment surface elevation dynamics and nitrogen accumulation in sediments were studied in experimental treatments planted with four different densities (6.96, 3.26, 1.93 and 0.95 seedlings m−2) of the mangrove Rhizophora mucronata in Puttalam Lagoon, Sri Lanka. Measurements were taken over a period of 1,171 days and were compared with those from unplanted controls. Trees at the lowest density showed significantly reduced survival, whilst measures of individual tree growth did not differ among treatments. Rates of surface sediment accretion (means ± SE) were 13.0 (±1.3), 10.5 (±0.9), 8.4 (±0.3), 6.9 (±0.5) and 5.7 (±0.3) mm year−1 at planting densities of 6.96, 3.26, 1.93, 0.95, and 0 (unplanted control) seedlings m−2, respectively, showing highly significant differences among treatments. Mean (±SE) rates of surface elevation change were much lower than rates of accretion at 2.8 (±0.2), 1.6 (±0.1), 1.1 (±0.2), 0.6 (±0.2) and −0.3 (±0.1) mm year−1 for 6.96, 3.26, 1.93, 0.95, and 0 seedlings m−2, respectively. All planted treatments accumulated greater nitrogen concentrations in the sediment compared to the unplanted control. Sediment %N was significantly different among densities which suggests one potential causal mechanism for the facilitatory effects observed: high densities of plants potentially contribute to the accretion of greater amounts of nutrient rich sediment. While this potential process needs further research, this study demonstrated how higher densities of mangroves enhance rates of sediment accretion and surface elevation processes that may be crucial in mangrove ecosystem adaptation to sea-level rise. There was no evidence that increasing plant density evoked a trade-off with growth and survival of the planted trees. Rather, facilitatory effects enhanced survival at high densities, suggesting that managers may be able to take advantage of high plantation densities to help mitigate sea-level rise effects by encouraging positive sediment surface elevation.

The efficiency analysis of container port production using DEA panel data approaches

Abstract: Applications of Data Envelopment Analysis (DEA) to container port production have been largely restricted to standard DEA models using cross-sectional data. The efficiency results derived may be biased; for instance, as the result of random effects or a recent investment in future production. In overcoming this problem, panel data on container port production may be more suitable for medium- to long-term efficiency analysis. This paper evaluates available DEA panel data approaches by applying them to a sample of 25 leading container ports. Empirical results validate the necessity of utilizing panel data and reveal that considerable waste exists in container port production. It also provides a basis for assessing the competitiveness of container ports, for benchmarking best practice and identifying specific sources or causes of inefficiency.

Use of emotional touchpoints as a method of tapping into the experience of receiving compassionate care in a hospital setting

Abstract: Improving the patient and family experience in hospital and supporting people to deliver compassionate dignified care is a priority on the policy agenda in the UK. The purpose of this paper is to d...

Reproductive control via eviction (but not the threat of eviction) in banded mongooses

Abstract: Considerable research has focused on understanding variation in reproductive skew in cooperative animal societies, but the pace of theoretical development has far outstripped empirical testing of the models. One major class of model suggests that dominant individuals can use the threat of eviction to deter subordinate reproduction (the ‘restraint’ model), but this idea remains untested. Here, we use long-term behavioural and genetic data to test the assumptions of the restraint model in banded mongooses (Mungos mungo), a species in which subordinates breed regularly and evictions are common. We found that dominant females suffer reproductive costs when subordinates breed, and respond to these costs by evicting breeding subordinates from the group en masse, in agreement with the assumptions of the model. We found no evidence, however, that subordinate females exercise reproductive restraint to avoid being evicted in the first place. This means that the pattern of reproduction is not the result of a reproductive ‘transaction’ to avert the threat of eviction. We present a simple game theoretical analysis that suggests that eviction threats may often be ineffective to induce pre-emptive restraint among multiple subordinates and predicts that threats of eviction (or departure) will be much more effective in dyadic relationships and linear hierarchies. Transactional models may be more applicable to these systems. Greater focus on testing the assumptions rather than predictions of skew models can lead to a better understanding of how animals control each other’s reproduction, and the extent to which behaviour is shaped by overt acts versus hidden threats.