Zinc polycarboxylate dental cement for the controlled release of an active organic substance: proof of concept

The potential of employing zinc polycarboxylate dental cement as a controlled release material has been studied. Benzalkonium chloride was used as the active ingredient, and incorporated at concentrations of 1, 2 and 3% by mass within the cement. At these levels, there was no observable effect on the speed of setting. Release was followed using an ion-selective electrode to determine changes in chloride ion concentration with time. This technique showed that the additive was released when the cured cement was placed in water, with release occurring by a diffusion mechanism for the first 3 h, but continuing beyond that for up to 1 week. Diffusion coefficients were in the range 5.62 × 10(−6) cm(2) s(−1) (for 1% concentration) to 10.90 × 10(−6) cm(2) s(−1) (for 3% concentration). Up to 3% of the total loading of benzalkonium chloride was released from the zinc polycarboxylate after a week, which is similar to that found in previous studies with glass-ionomer cement. It is concluded that zinc polycarboxylate cement is capable of acting as a useful material for the controlled release of active organic compounds.

The influence of crank configuration on muscle activity and torque production during arm crank ergometry

This study investigated the effect of crank configuration on muscle activity and torque production during submaximal arm crank ergometry. Thirteen non-specifically trained male participants volunteered. During the research trials they completed a warm-up at 15 W before two 3-min exercise stages were completed at 50 and 100 W; subjects used either a synchronous or asynchronous pattern of cranking. During the final 30-s of each submaximal exercise stage electromyographic and torque production data were collected. After the data had been processed each parameter was analysed using separate 2-way ANOVA tests with repeated measures. The activity of all muscles increased in line with external workload, although a shift in the temporal pattern of muscle activity was noted between crank configurations. Patterns of torque production during asynchronous and synchronous cranking were distinct. Furthermore, peak, minimum and delta (peak-minimum) torque values were different (P < 0.05) between crank configurations at both workloads. For example, at 100 W, peak torque using synchronous [19.6 (4.3) Nm] cranking was higher (P < 0.05) compared to asynchronous [16.8 (1.6) Nm] cranking. In contrast minimum torque was lower (P < 0.05) at 100 W using synchronous [4.8 (1.7) Nm] compared to asynchronous [7.3 (1.2) Nm] cranking. There was a distinct bilateral asymmetry in torque production during asynchronous cranking with the dominant transmitting significantly more force to the crank arm. Taken together, these preliminary data demonstrate the complex nature of muscle activity during arm crank ergometry performed with an asynchronous or synchronous crank set-up. Further work is required to determine how muscle activity (EMG activity) and associated patterns of torque production influence physiological responses and functional capacity during arm crank ergometry.

Systematic review of worldwide variations of the prevalence of wheezing symptoms in children

Background: Considerable variation in the prevalence of childhood asthma and its symptoms (wheezing) has been observed in previous studies and there is evidence that the prevalence has been increasing over time. Methods: We have systematically reviewed the reported prevalence and time trends of wheezing symptoms among children, worldwide and within the same country over time. All studies comprising more than 1000 persons and meeting certain other quality criteria published over a 16-year period, between January 1990 and December 2005, are reported and a comparison of ISAAC (International Study of Asthma and Allergies in Childhood) and non-ISAAC studies is made, in part as a way of expanding the power to examine time trends (the older studies tend to be non-ISAAC), but also to examine possible methodological differences between ISAAC and non-ISAAC questions. Results: A wide range of current prevalence of wheeze was observed between and within countries over time. The UK had the highest recorded prevalence of 32.2% in children aged 13–14 in 1994–5 and Ethiopia had the lowest prevalence, 1.7% in children aged 10–19 in 1996. All studies in Australia and the UK were compared using multiple logistic regression. ISAAC phase I and III studies reported significantly higher prevalence of current wheeze (OR = 1.638) compared with non-ISAAC studies, after adjusting for various other factors (country, survey year, age of child, parental vs child response to the survey). Australia showed a significantly higher prevalence of current wheezing (OR = 1.343) compared with the UK, there was a significant increase in the prevalence odds ratio per survey year (2.5% per year), a significant decrease per age of child (0.7% per year), and a significantly higher response in current wheezing if the response was self-completed by the child (OR = 1.290). These factors, when explored separately for ISAAC and non-ISAAC studies, showed very different results. In ISAAC studies, or non-ISAAC studies using ISAAC questions, there was a significant decrease in current wheezing prevalence over time (2.5% per year). In non-ISAAC studies, which tend to cover an earlier period, there was a significant increase (2.6% per year) in current wheezing prevalence over time. This is very likely to be a result of prevalence of wheezing increasing from the 1970s up to the early 1990s, but decreasing since then. Conclusion: The UK has the highest recorded prevalence of wheezing and Ethiopia the lowest. Prevalence of wheezing in Australia and the UK has increased from the 1970s up to the early 1990s, but decreased since then and ISAAC studies report significantly higher prevalences than non-ISAAC studies.

Exploring strategies for promoting the use of research findings in practice

Following the integration of nurse and midwifery education into institutions of higher education in the United Kingdom, a number of studies have shown that a defined clinical framework for nursing and midwifery lecturers in practice areas is lacking. The aim of this study was to explore strategies that nurse and midwifery lecturers from one higher education institution in south east England can use to work collaboratively with nurses and midwives to promote the utilization of research findings in practice. A cross-sectional survey using a structured questionnaire was sent to a sample of 60 nurse and midwifery lecturers and 90 clinical managers. Response rates of 67% (40) and 69% (62) respectively were obtained. The main strategies suggested were to make clinical staff more aware of what research exist in their specialties; to help them to access research information from research databases; and to critically appraise this information. Other strategies were for teachers to run research workshops on site; to undertake joint research projects with clinical staff; to set up journal clubs or research interest groups; and to help formulate clinical guidelines and protocols which are explicitly research-based.

Policy packages as potential routes to urban road pricing in the UK

This paper focuses on urban road pricing as a demand management policy that is often regarded as radical and generally unacceptable. Road pricing often gets delayed or abandoned due to low acceptability. This may be due to the fact that complex interactions and drivers of change affect road transport management and require cooperation within implementation networks. The implementation network is a group of people (referred to as partners and actors) who co-ordinate the introduction of policy tools. The drivers of change include any internal or external influences that have an effect on the time, place, or ‘shape’ of the policy measures being introduced. Demand management measures that focus on 'sustainable transport' usually address a limited set of objectives and are often implemented alone i.e. are not necessarily combined with other policy measures. When combined with other measures, it is not always clear whether the multiple interactions between policy tools and implementation networks have been sufficiently considered. Examples of ongoing implementation of policy package in the UK are the support of road pricing initiatives combined with public transport improvements by the Transport Innovation Fund. The objectives of the paper are twofold. First, we present a review of the UK urban road pricing situation. Second, we contrast the emerging issues against six key implementation factors. The analysis of three existing UK road pricing examples - London, Edinburgh and Durham – shows the importance of combining policy tools. Furthermore, through the above examples and theoretical arguments, we emphasise the additional need of creating and maintaining strong networks when implementing policy packages.

Start-up and running forces on bulk solids feeders: experimental findings versus available models

Many different models have been postulated over the years for sizing of feeder drives; these models have different bases, some rationally based and others more rule-of-thumb. Experience of Jenike & Johanson and likewise of The Wolfson Centre in trouble-shooting feeder drives has shown that drive powers are often poorly matched, so there is clearly still some way to go towards establishing a universally-used reliable approach. This paper presents an on-going programme of work designed to measure feeder forces experimentally on a purpose designed testing rig, and to compare these against some of the best known available models, and also against a full size installation. One aspect which is novel is the monitoring of the transition between the “filling stress field” load on the feeder and the “flowing stress field” load.

North Atlantic and North Sea climate change: curl up, shut down, NAO and ocean colour

The strength of the North Atlantic Current (NAC) (based on sea-surface elevation sloped derived from altimeter data) is correlated with westerly winds (based on North Atlantic Oscillation [NAO] Index data over a nine year period [1992-2002] with 108 monthly values). The data time window includes the major change in climate forcing over the last 100 years (1995 to 1996). It is shown that the NAO Index can be used for early earning of system failure for the NAC. The correlation response or early warning time scale for western Europe and south England is six months. The decay scale for the NAC and Subtropical Gyre circulation is estimated as three years. Longer period altimeter elevation/circulation changes are discussed. The sea-surface temperature (SST) response of the North Sea to negative and positive NAO conditions is examined. The overall temperature response for the central North Sea to NAO index forcing, reflecting wind induced inflow, shelf circulation and local climate forcing, is similar to 5 months. In years with strong North Atlantic winter wind induced inflow, under marked NAO positive conditions, mean temperatures ( similar to 10.5 degree C) are about 1 degree C warmer than under negative conditions. In 1996 under extreme negative winter NAO conditions, the North Sea circulation stopped, conditions near the Dogger Bank became more continentally influenced and the winter (March) temperature fell to 3.1 degree C whereas in 1995 under NAO positive winter conditions the minimum temperature was 6.4 degree C (February). Seasonal advance of North Atlantic and North Sea temperature is derived in relation to temperature change. Temperature change and monthly NAO Index are discussed with respect to phytoplankton blooms, chlorophyll-a measurements, ocean colour data and the anomalous north-eastern Atlantic 2002 spring/summer bloom SeaWiFS chlorophyll concentrations.

From plankton to top predators: bottom-up control of a marine food web across four trophic levels

1. Abundant mid-trophic pelagic fish often play a central role in marine ecosystems, both as links between zooplankton and top predators and as important fishery targets. In the North Sea, the lesser sandeel occupies this position, being the main prey of many bird, mammal and fish predators and the target of a major industrial fishery. However, since 2003, sandeel landings have decreased by > 50%, and many sandeel-dependent seabirds experienced breeding failures in 2004. 2. Despite the major economic implications, current understanding of the regulation of key constituents of this ecosystem is poor. Sandeel abundance may be regulated 'bottom-up' by food abundance, often thought to be under climatic control, or 'top-down' by natural or fishery predation. We tested predictions from these two hypotheses by combining unique long-term data sets (1973–2003) on seabird breeding productivity from the Isle of May, SE Scotland, and plankton and fish larvae from the Continuous Plankton Recorder survey. We also tested whether seabird breeding productivity was more tightly linked to sandeel biomass or quality (size) of individual fish. 3. The biomass of larval sandeels increased two- to threefold over the study period and was positively associated with proxies of the abundance of their plankton prey. Breeding productivity of four seabirds bringing multiple prey items to their offspring was positively related to sandeel larval biomass with a 1-year lag, indicating dependence on 1-year-old fish, but in one species bringing individual fish it was strongly associated with the size of adult sandeels. 4. These links are consistent with bottom-up ecosystem regulation and, with evidence from previous studies, indicate how climate-driven changes in plankton communities can affect top predators and potentially human fisheries through the dynamics of key mid-trophic fish. However, the failing recruitment to adult sandeel stocks and the exceptionally low seabird breeding productivity in 2004 were not associated with low sandeel larval biomass in 2003, so other mechanisms (e.g. predation, lack of suitable food after metamorphosis) must have been important in this case. Understanding ecosystem regulation is extremely important for predicting the fate of keystone species, such as sandeels, and their predators.

Bottom-up effects of climate on fish populations: data from the Continuous Plankton Recorder

The Continuous Plankton Recorder (CPR) dataset on fish larvae has an extensive spatio-temporal coverage that allows the responses of fish populations to past changes in climate variability, including abrupt changes such as regime shifts, to be investigated. The newly available dataset offers a unique opportunity to investigate long-term changes over decadal scales in the abundance and distribution of fish larvae in relation to physical and biological factors. A principal component analysis (PCA) using 7 biotic and abiotic parameters is applied to investigate the impact of environmental changes in the North Sea on 5 selected taxa of fish larvae during the period 1960 to 2004. The analysis revealed 4 periods of time (1960–1976; 1977–1982; 1983–1996; 1997–2004) reflecting 3 different ecosystem states. The larvae of clupeids, sandeels, dab and gadoids seemed to be affected mainly by changes in the plankton ecosystem, while the larvae of migratory species such as Atlantic mackerel responded more to hydrographic changes. Climate variability seems more likely to influence fish populations through bottom-up control via a cascading effect from changes in the North Atlantic Oscillation (NAO) impacting on the hydro dynamic features of the North Sea, in turn impacting on the plankton available as prey for fish larvae. The responses and adaptability of fish larvae to changing environmental conditions, parti cularly to changes in prey availability, are complex and species-specific. This complexity is enhanced with fishing effects interacting with climate effects and this study supports furthering our under - standing of such interactions before attempting to predict how fish populations respond to climate variability