Critical evaluation of pulse-echo ultrasonic test method for the determination of setting and mechanical properties of acrylic bone cement: Influence of mixing technique

Currently there is no reliable objective method to quantify the setting properties of acrylic bone cements within an operating theatre environment. Ultrasonic technology can be used to determine the acoustic properties of the polymerising bone cement, which are linked to material properties and provide indications of the physical and chemical changes occurring within the cement. The focus of this study was the critical evaluation of pulse-echo ultrasonic test method in determining the setting and mechanical properties of three different acrylic bone cement when prepared under atmospheric and vacuum mixing conditions. Results indicated that the ultrasonic pulse-echo technique provided a highly reproducible and accurate method of monitoring the polymerisation reaction and indicating the principal setting parameters when compared to ISO 5833 standard, irrespective of the acrylic bone cement or mixing method used. However, applying the same test method to predict the final mechanical properties of acrylic bone cement did not prove a wholly accurate approach. Inhomogeneities within the cement microstructure and specimen geometry were found to have a significant influence on mechanical property predictions. Consideration of all the results suggests that the non-invasive and non-destructive pulse-echo ultrasonic test method is an effective and reliable method for following the full polymerisation reaction of acrylic bone cement in real-time and then determining the setting properties within a surgical theatre environment. However the application of similar technology for predicting the final mechanical properties of acrylic bone cement on a consistent basis may prove difficult.

Revision rules in the theory of evidence

Combination rules proposed so far in the Dempster-Shafer theory of evidence, especially Dempster rule, rely on a basic assumption, that is, pieces of evidence being combined are considered to be on a par, i.e. play the same role. When a source of evidence is less reliable than another, it is possible to discount it and then a symmetric combination operation is still used. In the case of revision, the idea is to let prior knowledge of an agent be altered by some input information. The change problem is thus intrinsically asymmetric. Assuming the input information is reliable, it should be retained whilst the prior information should
be changed minimally to that effect. Although belief revision is already an important subfield of artificial intelligence, so far, it has been little addressed in evidence theory. In this paper, we define the notion of revision for the theory of evidence and propose several different revision rules, called the inner and outer
revisions, and a modified adaptive outer revision, which better corresponds to the idea of revision. Properties of these revision rules are also investigated.

An investigation into the factors influencing tooth brushing behaviour amongst school children living in Northern Ireland: An application of the Theory of Planned Behaviour.

Background: Northern Ireland has the worst oral health in the UK and its children have among the highest levels of tooth decay in Europe (DHSSPS, 2007).
Aim: The aim of this study is to investigate the factors influencing tooth brushing behaviour among Year 6 primary schoolchildren using the Theory of Planned Behaviour (TPB).
Method: Seven semi-structured focus groups involving 56 children were conducted during which children were asked questions about the factors that influence whether or not they brush their teeth. Thematic analysis was used with the purpose of eliciting the belief-based measures for all the TPB constructs.
Results: The findings suggest that children are knowledgeable about their teeth and are aware of the importance of maintaining good oral health; although a number of barriers to consistent tooth brushing exist.
Discussion: The findings will be used to inform stage 2 of the research project; questionnaire development to identify the factors influencing young people’s motivations to improve their tooth brushing behaviour and to assess their relative importance.

A critical review of labelling techniques used to quantify rhizosphere carbon-flow

The rhizosphere is a major sink for photo-assimilated carbon and quantifying inputs into this sink is one of the main goals of rhizosphere biology as organic carbon lost from plant roots supports a higher microbial population in the rhizosphere compared to bulk soil. Two fundamentally different¹⁴CO₂ labelling strategies have been developed to estimate carbon fluxes through the rhizosphere - continuous feeding of shoots with labelled carbon dioxide and pulse-chase experiments. The biological interpretation that can be placed on the results of labelling experiments is greatly biased by the technique used. It is the purpose of this paper to assess the advantages, disadvantages and the biological interpretation of both continuous and pulse labelling and to consider how to partition carbon fluxes within the rhizosphere. © 1994 Kluwer Academic Publishers.

Management of polycythaemia vera: a critical review of current data

Polycythaemia vera (PV) is a chronic blood cancer; its clinical features are dominated by myeloproliferation (erythrocytosis, often leucocytosis and/or thrombocytosis) and a tendency for thrombosis and transformation to myelofibrosis or acute myeloid leukaemia. In the past 10 years the pathophysiology of this condition has been defined as JAK/STAT pathway activation, almost always due to mutations in JAK2 exons 12 or 14 (JAK2 V617F). In the same time period our understanding of the optimal management of PV has expanded, most recently culminating in the approval of JAK inhibitors for the treatment of PV patients who are resistant or intolerant to therapy with hydroxycarbamide. It has also been demonstrated that life expectancy for many patients with PV is not normal, nor is their quality of life. We critically explore these findings and discuss their impact. In addition, we highlight persisting gaps in our current management strategy; for example, what is the optimal first line cytoreductive therapy and, indeed, which patients need cytoreductive drugs.

Intentions Toward Physical Activity and Resting Behavior in Pregnant Women: Using the Theory of Planned Behavior Framework in a Cross-Sectional Study

BACKGROUND: Pregnant women are recommended to 1) perform daily moderate-intensity physical activity and 2) limit the amount of sedentary time. Many women do not meet these recommendations. Reduced physical activity and increased sedentary behavior may result from women actively intending to rest during pregnancy. The Theory of Planned Behavior (TPB) has been used to assess attitudes (e.g., positive/negative beliefs), subjective norms (e.g., perception of others' views), perceived behavioral control (PBC) (e.g., self-efficacy), and intention toward exercising while pregnant but has not been applied to aspects pertaining to resting during pregnancy.

METHODS: Pregnant women (n = 345) completed a cross-sectional questionnaire that included two TPB Questionnaires where the target behaviors were 1) being physically active and 2) resting. Bootstrapped paired t tests, ANOVA, and linear hierarchal regression analyses were performed to identify predictors of intentions and whether intentions toward the two behaviors varied at different stages of pregnancy.

RESULTS: As women progressed in their pregnancy, their attitude, PBC, and intention toward being physically active all significantly declined. A positive attitude, subjective norms, and intention toward resting all significantly increased with the advancing trimester. Self-reported health conditions predicted lower intention for physical activity but not for resting.

DISCUSSION: The significantly inverse relationship between physical activity and resting across time suggests that women feel they should focus on one behavior at the expense of the other. Finding that women generally do not perceive these behaviors as mutually compatible has implications in strategizing as to how to encourage women to be active during pregnancy.